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// statements.cc -- Go frontend statements.
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "go-system.h"
#include "go-c.h"
#include "go-diagnostics.h"
#include "types.h"
#include "expressions.h"
#include "gogo.h"
#include "export.h"
#include "import.h"
#include "runtime.h"
#include "backend.h"
#include "statements.h"
#include "ast-dump.h"
// Class Statement.
Statement::Statement(Statement_classification classification,
Location location)
: classification_(classification), location_(location)
{
}
Statement::~Statement()
{
}
// Traverse the tree. The work of walking the components is handled
// by the subclasses.
int
Statement::traverse(Block* block, size_t* pindex, Traverse* traverse)
{
if (this->classification_ == STATEMENT_ERROR)
return TRAVERSE_CONTINUE;
unsigned int traverse_mask = traverse->traverse_mask();
if ((traverse_mask & Traverse::traverse_statements) != 0)
{
int t = traverse->statement(block, pindex, this);
if (t == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
else if (t == TRAVERSE_SKIP_COMPONENTS)
return TRAVERSE_CONTINUE;
}
// No point in checking traverse_mask here--a statement may contain
// other blocks or statements, and if we got here we always want to
// walk them.
return this->do_traverse(traverse);
}
// Traverse the contents of a statement.
int
Statement::traverse_contents(Traverse* traverse)
{
return this->do_traverse(traverse);
}
// Traverse assignments.
bool
Statement::traverse_assignments(Traverse_assignments* tassign)
{
if (this->classification_ == STATEMENT_ERROR)
return false;
return this->do_traverse_assignments(tassign);
}
// Traverse an expression in a statement. This is a helper function
// for child classes.
int
Statement::traverse_expression(Traverse* traverse, Expression** expr)
{
if ((traverse->traverse_mask()
& (Traverse::traverse_types | Traverse::traverse_expressions)) == 0)
return TRAVERSE_CONTINUE;
return Expression::traverse(expr, traverse);
}
// Traverse an expression list in a statement. This is a helper
// function for child classes.
int
Statement::traverse_expression_list(Traverse* traverse,
Expression_list* expr_list)
{
if (expr_list == NULL)
return TRAVERSE_CONTINUE;
if ((traverse->traverse_mask()
& (Traverse::traverse_types | Traverse::traverse_expressions)) == 0)
return TRAVERSE_CONTINUE;
return expr_list->traverse(traverse);
}
// Traverse a type in a statement. This is a helper function for
// child classes.
int
Statement::traverse_type(Traverse* traverse, Type* type)
{
if ((traverse->traverse_mask()
& (Traverse::traverse_types | Traverse::traverse_expressions)) == 0)
return TRAVERSE_CONTINUE;
return Type::traverse(type, traverse);
}
// Set type information for unnamed constants. This is really done by
// the child class.
void
Statement::determine_types()
{
this->do_determine_types();
}
// Read a statement from export data.
Statement*
Statement::import_statement(Import_function_body* ifb, Location loc)
{
if (ifb->match_c_string("{"))
{
bool is_lowered_for_statement;
Block* block = Block_statement::do_import(ifb, loc,
&is_lowered_for_statement);
if (block == NULL)
return Statement::make_error_statement(loc);
Block_statement* s = Statement::make_block_statement(block, loc);
if (is_lowered_for_statement)
s->set_is_lowered_for_statement();
return s;
}
else if (ifb->match_c_string("return"))
{
// After lowering return statements have no expressions. The
// return expressions are assigned to result parameters.
ifb->advance(6);
return Statement::make_return_statement(NULL, loc);
}
else if (ifb->match_c_string("var $t"))
return Temporary_statement::do_import(ifb, loc);
else if (ifb->match_c_string("var "))
return Variable_declaration_statement::do_import(ifb, loc);
else if (ifb->match_c_string("if "))
return If_statement::do_import(ifb, loc);
else if (ifb->match_c_string(":"))
return Label_statement::do_import(ifb, loc);
else if (ifb->match_c_string("goto "))
return Goto_statement::do_import(ifb, loc);
Expression* lhs = Expression::import_expression(ifb, loc);
if (ifb->match_c_string(" //"))
return Statement::make_statement(lhs, true);
ifb->require_c_string(" = ");
Expression* rhs = Expression::import_expression(ifb, loc);
return Statement::make_assignment(lhs, rhs, loc);
}
// If this is a thunk statement, return it.
Thunk_statement*
Statement::thunk_statement()
{
Thunk_statement* ret = this->convert<Thunk_statement, STATEMENT_GO>();
if (ret == NULL)
ret = this->convert<Thunk_statement, STATEMENT_DEFER>();
return ret;
}
// Convert a Statement to the backend representation. This is really
// done by the child class.
Bstatement*
Statement::get_backend(Translate_context* context)
{
if (this->classification_ == STATEMENT_ERROR)
return context->backend()->error_statement();
return this->do_get_backend(context);
}
// Dump AST representation for a statement to a dump context.
void
Statement::dump_statement(Ast_dump_context* ast_dump_context) const
{
this->do_dump_statement(ast_dump_context);
}
// Note that this statement is erroneous. This is called by children
// when they discover an error.
void
Statement::set_is_error()
{
this->classification_ = STATEMENT_ERROR;
}
// For children to call to report an error conveniently.
void
Statement::report_error(const char* msg)
{
go_error_at(this->location_, "%s", msg);
this->set_is_error();
}
// An error statement, used to avoid crashing after we report an
// error.
class Error_statement : public Statement
{
public:
Error_statement(Location location)
: Statement(STATEMENT_ERROR, location)
{ }
protected:
int
do_traverse(Traverse*)
{ return TRAVERSE_CONTINUE; }
Bstatement*
do_get_backend(Translate_context*)
{ go_unreachable(); }
void
do_dump_statement(Ast_dump_context*) const;
};
//
// Helper to tack on available source position information
// at the end of a statement.
//
static std::string
dsuffix(Location location)
{
std::string lstr = Linemap::location_to_string(location);
if (lstr == "")
return lstr;
std::string rval(" // ");
rval += lstr;
return rval;
}
// Dump the AST representation for an error statement.
void
Error_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->ostream() << "Error statement" << std::endl;
}
// Make an error statement.
Statement*
Statement::make_error_statement(Location location)
{
return new Error_statement(location);
}
// Class Variable_declaration_statement.
Variable_declaration_statement::Variable_declaration_statement(
Named_object* var)
: Statement(STATEMENT_VARIABLE_DECLARATION, var->var_value()->location()),
var_(var)
{
}
// We don't actually traverse the variable here; it was traversed
// while traversing the Block.
int
Variable_declaration_statement::do_traverse(Traverse*)
{
return TRAVERSE_CONTINUE;
}
// Traverse the assignments in a variable declaration. Note that this
// traversal is different from the usual traversal.
bool
Variable_declaration_statement::do_traverse_assignments(
Traverse_assignments* tassign)
{
tassign->initialize_variable(this->var_);
return true;
}
// Lower the variable's initialization expression.
Statement*
Variable_declaration_statement::do_lower(Gogo* gogo, Named_object* function,
Block*, Statement_inserter* inserter)
{
this->var_->var_value()->lower_init_expression(gogo, function, inserter);
return this;
}
// Flatten the variable's initialization expression.
Statement*
Variable_declaration_statement::do_flatten(Gogo* gogo, Named_object* function,
Block*, Statement_inserter* inserter)
{
Variable* var = this->var_->var_value();
if (var->type()->is_error_type()
|| (var->init() != NULL
&& var->init()->is_error_expression()))
{
go_assert(saw_errors());
return Statement::make_error_statement(this->location());
}
this->var_->var_value()->flatten_init_expression(gogo, function, inserter);
return this;
}
// Add explicit type conversions.
void
Variable_declaration_statement::do_add_conversions()
{
Variable* var = this->var_->var_value();
Expression* init = var->init();
if (init == NULL)
return;
Type* lt = var->type();
Type* rt = init->type();
if (!Type::are_identical(lt, rt, 0, NULL)
&& lt->interface_type() != NULL)
var->set_init(Expression::make_cast(lt, init, this->location()));
}
// Convert a variable declaration to the backend representation.
Bstatement*
Variable_declaration_statement::do_get_backend(Translate_context* context)
{
Bfunction* bfunction = context->function()->func_value()->get_decl();
Variable* var = this->var_->var_value();
Bvariable* bvar = this->var_->get_backend_variable(context->gogo(),
context->function());
Bexpression* binit = var->get_init(context->gogo(), context->function());
if (!var->is_in_heap())
{
go_assert(binit != NULL);
return context->backend()->init_statement(bfunction, bvar, binit);
}
// Something takes the address of this variable, so the value is
// stored in the heap. Initialize it to newly allocated memory
// space, and assign the initial value to the new space.
Location loc = this->location();
Named_object* newfn = context->gogo()->lookup_global("new");
go_assert(newfn != NULL && newfn->is_function_declaration());
Expression* func = Expression::make_func_reference(newfn, NULL, loc);
Expression_list* params = new Expression_list();
params->push_back(Expression::make_type(var->type(), loc));
Expression* call = Expression::make_call(func, params, false, loc);
context->gogo()->lower_expression(context->function(), NULL, &call);
Temporary_statement* temp = Statement::make_temporary(NULL, call, loc);
Bstatement* btemp = temp->get_backend(context);
Bstatement* set = NULL;
if (binit != NULL)
{
Expression* e = Expression::make_temporary_reference(temp, loc);
e = Expression::make_dereference(e, Expression::NIL_CHECK_NOT_NEEDED,
loc);
Bexpression* be = e->get_backend(context);
set = context->backend()->assignment_statement(bfunction, be, binit, loc);
}
Expression* ref = Expression::make_temporary_reference(temp, loc);
Bexpression* bref = ref->get_backend(context);
Bstatement* sinit = context->backend()->init_statement(bfunction, bvar, bref);
std::vector<Bstatement*> stats;
stats.reserve(3);
stats.push_back(btemp);
if (set != NULL)
stats.push_back(set);
stats.push_back(sinit);
return context->backend()->statement_list(stats);
}
// Dump the AST representation for a variable declaration.
void
Variable_declaration_statement::do_dump_statement(
Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
go_assert(var_->is_variable());
ast_dump_context->ostream() << "var " << this->var_->name() << " ";
Variable* var = this->var_->var_value();
if (var->has_type())
{
ast_dump_context->dump_type(var->type());
ast_dump_context->ostream() << " ";
}
if (var->init() != NULL)
{
ast_dump_context->ostream() << "= ";
ast_dump_context->dump_expression(var->init());
}
ast_dump_context->ostream() << dsuffix(location()) << std::endl;
}
// Make a variable declaration.
Statement*
Statement::make_variable_declaration(Named_object* var)
{
return new Variable_declaration_statement(var);
}
// Export a variable declaration.
void
Variable_declaration_statement::do_export_statement(Export_function_body* efb)
{
efb->write_c_string("var ");
efb->write_string(Gogo::unpack_hidden_name(this->var_->name()));
efb->write_c_string(" ");
Variable* var = this->var_->var_value();
Type* type = var->type();
efb->write_type(type);
Expression* init = var->init();
if (init != NULL)
{
efb->write_c_string(" = ");
go_assert(efb->type_context() == NULL);
efb->set_type_context(type);
init->export_expression(efb);
efb->set_type_context(NULL);
}
}
// Import a variable declaration.
Statement*
Variable_declaration_statement::do_import(Import_function_body* ifb,
Location loc)
{
ifb->require_c_string("var ");
std::string id = ifb->read_identifier();
ifb->require_c_string(" ");
Type* type = ifb->read_type();
Expression* init = NULL;
if (ifb->match_c_string(" = "))
{
ifb->advance(3);
init = Expression::import_expression(ifb, loc);
}
Variable* var = new Variable(type, init, false, false, false, loc);
var->set_is_used();
// FIXME: The package we are importing does not yet exist, so we
// can't pass the correct package here. It probably doesn't matter.
Named_object* no = ifb->block()->bindings()->add_variable(id, NULL, var);
return Statement::make_variable_declaration(no);
}
// Class Temporary_statement.
// Return the type of the temporary variable.
Type*
Temporary_statement::type() const
{
Type* type = this->type_ != NULL ? this->type_ : this->init_->type();
// Temporary variables cannot have a void type.
if (type->is_void_type())
{
go_assert(saw_errors());
return Type::make_error_type();
}
return type;
}
// Traversal.
int
Temporary_statement::do_traverse(Traverse* traverse)
{
if (this->type_ != NULL
&& this->traverse_type(traverse, this->type_) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
if (this->init_ == NULL)
return TRAVERSE_CONTINUE;
else
return this->traverse_expression(traverse, &this->init_);
}
// Traverse assignments.
bool
Temporary_statement::do_traverse_assignments(Traverse_assignments* tassign)
{
if (this->init_ == NULL)
return false;
tassign->value(&this->init_, true, true);
return true;
}
// Determine types.
void
Temporary_statement::do_determine_types()
{
if (this->type_ != NULL && this->type_->is_abstract())
this->type_ = this->type_->make_non_abstract_type();
if (this->init_ != NULL)
{
if (this->type_ == NULL)
this->init_->determine_type_no_context();
else
{
Type_context context(this->type_, false);
this->init_->determine_type(&context);
}
}
if (this->type_ == NULL)
{
this->type_ = this->init_->type();
go_assert(!this->type_->is_abstract());
}
}
// Check types.
void
Temporary_statement::do_check_types(Gogo*)
{
if (this->type_ != NULL && this->init_ != NULL)
{
std::string reason;
if (!Type::are_assignable(this->type_, this->init_->type(), &reason))
{
if (reason.empty())
go_error_at(this->location(), "incompatible types in assignment");
else
go_error_at(this->location(), "incompatible types in assignment (%s)",
reason.c_str());
this->set_is_error();
}
}
}
// Flatten a temporary statement: add another temporary when it might
// be needed for interface conversion.
Statement*
Temporary_statement::do_flatten(Gogo*, Named_object*, Block*,
Statement_inserter* inserter)
{
if (this->type()->is_error_type()
|| (this->init_ != NULL
&& this->init_->is_error_expression()))
{
go_assert(saw_errors());
return Statement::make_error_statement(this->location());
}
if (this->type_ != NULL
&& this->init_ != NULL
&& !Type::are_identical(this->type_, this->init_->type(),
Type::COMPARE_ERRORS | Type::COMPARE_TAGS,
NULL)
&& this->init_->type()->interface_type() != NULL
&& !this->init_->is_variable())
{
Temporary_statement *temp =
Statement::make_temporary(NULL, this->init_, this->location());
inserter->insert(temp);
this->init_ = Expression::make_temporary_reference(temp,
this->location());
}
return this;
}
// Add explicit type conversions.
void
Temporary_statement::do_add_conversions()
{
if (this->init_ == NULL)
return;
Type* lt = this->type();
Type* rt = this->init_->type();
if (!Type::are_identical(lt, rt, 0, NULL)
&& lt->interface_type() != NULL)
this->init_ = Expression::make_cast(lt, this->init_, this->location());
}
// Convert to backend representation.
Bstatement*
Temporary_statement::do_get_backend(Translate_context* context)
{
go_assert(this->bvariable_ == NULL);
Named_object* function = context->function();
go_assert(function != NULL);
Bfunction* bfunction = function->func_value()->get_decl();
Btype* btype = this->type()->get_backend(context->gogo());
Bexpression* binit;
if (this->init_ == NULL)
binit = NULL;
else if (this->type_ == NULL)
binit = this->init_->get_backend(context);
else
{
Expression* init = Expression::convert_for_assignment(context->gogo(),
this->type_,
this->init_,
this->location());
binit = init->get_backend(context);
}
if (binit != NULL)
binit = context->backend()->convert_expression(btype, binit,
this->location());
Bstatement* statement;
this->bvariable_ =
context->backend()->temporary_variable(bfunction, context->bblock(),
btype, binit,
this->is_address_taken_,
this->location(), &statement);
return statement;
}
// Return the backend variable.
Bvariable*
Temporary_statement::get_backend_variable(Translate_context* context) const
{
if (this->bvariable_ == NULL)
{
go_assert(saw_errors());
return context->backend()->error_variable();
}
return this->bvariable_;
}
// Dump the AST represemtation for a temporary statement
void
Temporary_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->dump_temp_variable_name(this);
if (this->type_ != NULL)
{
ast_dump_context->ostream() << " ";
ast_dump_context->dump_type(this->type_);
}
if (this->init_ != NULL)
{
ast_dump_context->ostream() << " = ";
ast_dump_context->dump_expression(this->init_);
}
ast_dump_context->ostream() << dsuffix(location()) << std::endl;
}
// Make and initialize a temporary variable in BLOCK.
Temporary_statement*
Statement::make_temporary(Type* type, Expression* init,
Location location)
{
return new Temporary_statement(type, init, location);
}
// Export a temporary statement.
void
Temporary_statement::do_export_statement(Export_function_body* efb)
{
unsigned int idx = efb->record_temporary(this);
char buf[100];
snprintf(buf, sizeof buf, "var $t%u", idx);
efb->write_c_string(buf);
if (this->type_ != NULL)
{
efb->write_c_string(" ");
efb->write_type(this->type_);
}
if (this->init_ != NULL)
{
efb->write_c_string(" = ");
go_assert(efb->type_context() == NULL);
efb->set_type_context(this->type_);
this->init_->export_expression(efb);
efb->set_type_context(NULL);
}
}
// Import a temporary statement.
Statement*
Temporary_statement::do_import(Import_function_body* ifb, Location loc)
{
ifb->require_c_string("var ");
std::string id = ifb->read_identifier();
go_assert(id[0] == '$' && id[1] == 't');
const char *p = id.c_str();
char *end;
long idx = strtol(p + 2, &end, 10);
if (*end != '\0' || idx > 0x7fffffff)
{
if (!ifb->saw_error())
go_error_at(loc,
("invalid export data for %qs: "
"bad temporary statement index at %lu"),
ifb->name().c_str(),
static_cast<unsigned long>(ifb->off()));
ifb->set_saw_error();
return Statement::make_error_statement(loc);
}
Type* type = NULL;
if (!ifb->match_c_string(" = "))
{
ifb->require_c_string(" ");
type = ifb->read_type();
}
Expression* init = NULL;
if (ifb->match_c_string(" = "))
{
ifb->advance(3);
init = Expression::import_expression(ifb, loc);
}
if (type == NULL && init == NULL)
{
if (!ifb->saw_error())
go_error_at(loc,
("invalid export data for %qs: "
"temporary statement has neither type nor init at %lu"),
ifb->name().c_str(),
static_cast<unsigned long>(ifb->off()));
ifb->set_saw_error();
return Statement::make_error_statement(loc);
}
Temporary_statement* temp = Statement::make_temporary(type, init, loc);
ifb->record_temporary(temp, static_cast<unsigned int>(idx));
return temp;
}
// The Move_subexpressions class is used to move all top-level
// subexpressions of an expression. This is used for things like
// index expressions in which we must evaluate the index value before
// it can be changed by a multiple assignment.
class Move_subexpressions : public Traverse
{
public:
Move_subexpressions(int skip, Block* block)
: Traverse(traverse_expressions),
skip_(skip), block_(block)
{ }
protected:
int
expression(Expression**);
private:
// The number of subexpressions to skip moving. This is used to
// avoid moving the array itself, as we only need to move the index.
int skip_;
// The block where new temporary variables should be added.
Block* block_;
};
int
Move_subexpressions::expression(Expression** pexpr)
{
if (this->skip_ > 0)
--this->skip_;
else if ((*pexpr)->temporary_reference_expression() == NULL
&& !(*pexpr)->is_nil_expression()
&& !(*pexpr)->is_constant())
{
Location loc = (*pexpr)->location();
Temporary_statement* temp = Statement::make_temporary(NULL, *pexpr, loc);
this->block_->add_statement(temp);
*pexpr = Expression::make_temporary_reference(temp, loc);
}
// We only need to move top-level subexpressions.
return TRAVERSE_SKIP_COMPONENTS;
}
// The Move_ordered_evals class is used to find any subexpressions of
// an expression that have an evaluation order dependency. It creates
// temporary variables to hold them.
class Move_ordered_evals : public Traverse
{
public:
Move_ordered_evals(Block* block)
: Traverse(traverse_expressions),
block_(block)
{ }
protected:
int
expression(Expression**);
private:
// The block where new temporary variables should be added.
Block* block_;
};
int
Move_ordered_evals::expression(Expression** pexpr)
{
// We have to look at subexpressions first.
if ((*pexpr)->traverse_subexpressions(this) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
int i;
if ((*pexpr)->must_eval_subexpressions_in_order(&i))
{
Move_subexpressions ms(i, this->block_);
if ((*pexpr)->traverse_subexpressions(&ms) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
}
if ((*pexpr)->must_eval_in_order())
{
Call_expression* call = (*pexpr)->call_expression();
if (call != NULL && call->is_multi_value_arg())
{
// A call expression which returns multiple results as an argument
// to another call must be handled specially. We can't create a
// temporary because there is no type to give it. Instead, group
// the caller and this multi-valued call argument and use a temporary
// variable to hold them.
return TRAVERSE_SKIP_COMPONENTS;
}
Location loc = (*pexpr)->location();
Temporary_statement* temp = Statement::make_temporary(NULL, *pexpr, loc);
this->block_->add_statement(temp);
*pexpr = Expression::make_temporary_reference(temp, loc);
}
return TRAVERSE_SKIP_COMPONENTS;
}
// Class Assignment_statement.
// Traversal.
int
Assignment_statement::do_traverse(Traverse* traverse)
{
if (this->traverse_expression(traverse, &this->lhs_) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
return this->traverse_expression(traverse, &this->rhs_);
}
bool
Assignment_statement::do_traverse_assignments(Traverse_assignments* tassign)
{
tassign->assignment(&this->lhs_, &this->rhs_);
return true;
}
// Lower an assignment to a map index expression to a runtime function
// call. Mark some slice assignments as not requiring a write barrier.
Statement*
Assignment_statement::do_lower(Gogo* gogo, Named_object*, Block* enclosing,
Statement_inserter*)
{
Map_index_expression* mie = this->lhs_->map_index_expression();
if (mie != NULL)
{
Location loc = this->location();
Expression* map = mie->map();
Map_type* mt = map->type()->map_type();
if (mt == NULL)
{
go_assert(saw_errors());
return Statement::make_error_statement(loc);
}
Block* b = new Block(enclosing, loc);
// Move out any subexpressions on the left hand side to make
// sure that functions are called in the required order.
Move_ordered_evals moe(b);
mie->traverse_subexpressions(&moe);
// Copy the key into a temporary so that we can take its address
// without pushing the value onto the heap.
// var key_temp KEY_TYPE = MAP_INDEX
Temporary_statement* key_temp = Statement::make_temporary(mt->key_type(),
mie->index(),
loc);
b->add_statement(key_temp);
// Copy the value into a temporary to ensure that it is
// evaluated before we add the key to the map. This may matter
// if the value is itself a reference to the map.
// var val_temp VAL_TYPE = RHS
Temporary_statement* val_temp = Statement::make_temporary(mt->val_type(),
this->rhs_,
loc);
b->add_statement(val_temp);
// *mapassign(TYPE, MAP, &key_temp) = RHS
Expression* a1 = Expression::make_type_descriptor(mt, loc);
Expression* a2 = mie->map();
Temporary_reference_expression* ref =
Expression::make_temporary_reference(key_temp, loc);
Expression* a3 = Expression::make_unary(OPERATOR_AND, ref, loc);
Runtime::Function code;
Map_type::Map_alg alg = mt->algorithm(gogo);
switch (alg)
{
case Map_type::MAP_ALG_FAST32:
{
code = Runtime::MAPASSIGN_FAST32;
Type* uint32_type = Type::lookup_integer_type("uint32");
Type* uint32_ptr_type = Type::make_pointer_type(uint32_type);
a3 = Expression::make_unsafe_cast(uint32_ptr_type, a3,
loc);
a3 = Expression::make_dereference(a3,
Expression::NIL_CHECK_NOT_NEEDED,
loc);
break;
}
case Map_type::MAP_ALG_FAST64:
{
code = Runtime::MAPASSIGN_FAST64;
Type* uint64_type = Type::lookup_integer_type("uint64");
Type* uint64_ptr_type = Type::make_pointer_type(uint64_type);
a3 = Expression::make_unsafe_cast(uint64_ptr_type, a3,
loc);
a3 = Expression::make_dereference(a3,
Expression::NIL_CHECK_NOT_NEEDED,
loc);
break;
}
case Map_type::MAP_ALG_FAST32PTR:
case Map_type::MAP_ALG_FAST64PTR:
{
code = (alg == Map_type::MAP_ALG_FAST32PTR
? Runtime::MAPASSIGN_FAST32PTR
: Runtime::MAPASSIGN_FAST64PTR);
Type* ptr_type =
Type::make_pointer_type(Type::make_void_type());
Type* ptr_ptr_type = Type::make_pointer_type(ptr_type);
a3 = Expression::make_unsafe_cast(ptr_ptr_type, a3,
loc);
a3 = Expression::make_dereference(a3,
Expression::NIL_CHECK_NOT_NEEDED,
loc);
break;
}
case Map_type::MAP_ALG_FASTSTR:
code = Runtime::MAPASSIGN_FASTSTR;
a3 = ref;
break;
default:
code = Runtime::MAPASSIGN;
break;
}
Expression* call = Runtime::make_call(code, loc, 3,
a1, a2, a3);
Type* ptrval_type = Type::make_pointer_type(mt->val_type());
call = Expression::make_cast(ptrval_type, call, loc);
Expression* indir =
Expression::make_dereference(call, Expression::NIL_CHECK_NOT_NEEDED,
loc);
ref = Expression::make_temporary_reference(val_temp, loc);
b->add_statement(Statement::make_assignment(indir, ref, loc));
return Statement::make_block_statement(b, loc);
}
// An assignment of the form s = s[:n] does not require a write
// barrier, because the pointer value will not change.
Array_index_expression* aie = this->rhs_->array_index_expression();
if (aie != NULL
&& aie->end() != NULL
&& Expression::is_same_variable(this->lhs_, aie->array()))
{
Numeric_constant nc;
unsigned long ival;
if (aie->start()->numeric_constant_value(&nc)
&& nc.to_unsigned_long(&ival) == Numeric_constant::NC_UL_VALID
&& ival == 0)
this->omit_write_barrier_ = true;
}
String_index_expression* sie = this->rhs_->string_index_expression();
if (sie != NULL
&& sie->end() != NULL
&& Expression::is_same_variable(this->lhs_, sie->string()))
{
Numeric_constant nc;
unsigned long ival;
if (sie->start()->numeric_constant_value(&nc)
&& nc.to_unsigned_long(&ival) == Numeric_constant::NC_UL_VALID
&& ival == 0)
this->omit_write_barrier_ = true;
}
return this;
}
// Set types for the assignment.
void
Assignment_statement::do_determine_types()
{
this->lhs_->determine_type_no_context();
Type* rhs_context_type = this->lhs_->type();
if (rhs_context_type->is_sink_type())
rhs_context_type = NULL;
Type_context context(rhs_context_type, false);
this->rhs_->determine_type(&context);
}
// Check types for an assignment.
void
Assignment_statement::do_check_types(Gogo*)
{
// The left hand side must be either addressable, a map index
// expression, or the blank identifier.
if (!this->lhs_->is_addressable()
&& this->lhs_->map_index_expression() == NULL
&& !this->lhs_->is_sink_expression())
{
if (!this->lhs_->type()->is_error())
this->report_error(_("invalid left hand side of assignment"));
return;
}
Type* lhs_type = this->lhs_->type();
Type* rhs_type = this->rhs_->type();
// Invalid assignment of nil to the blank identifier.
if (lhs_type->is_sink_type()
&& rhs_type->is_nil_type())
{
this->report_error(_("use of untyped nil"));
return;
}
std::string reason;
if (!Type::are_assignable(lhs_type, rhs_type, &reason))
{
if (reason.empty())
go_error_at(this->location(), "incompatible types in assignment");
else
go_error_at(this->location(), "incompatible types in assignment (%s)",
reason.c_str());
this->set_is_error();
}
if (lhs_type->is_error() || rhs_type->is_error())
this->set_is_error();
}
void
Assignment_statement::do_export_statement(Export_function_body* efb)
{
this->lhs_->export_expression(efb);
efb->write_c_string(" = ");
this->rhs_->export_expression(efb);
}
// Flatten an assignment statement. We may need a temporary for
// interface conversion.
Statement*
Assignment_statement::do_flatten(Gogo*, Named_object*, Block*,
Statement_inserter* inserter)
{
if (this->lhs_->is_error_expression()
|| this->lhs_->type()->is_error_type()
|| this->rhs_->is_error_expression()
|| this->rhs_->type()->is_error_type())
{
go_assert(saw_errors());
return Statement::make_error_statement(this->location());
}
if (!this->lhs_->is_sink_expression()
&& !Type::are_identical(this->lhs_->type(), this->rhs_->type(),
Type::COMPARE_ERRORS | Type::COMPARE_TAGS,
NULL)
&& this->rhs_->type()->interface_type() != NULL
&& !this->rhs_->is_variable())
{
Temporary_statement* temp =
Statement::make_temporary(NULL, this->rhs_, this->location());
inserter->insert(temp);
this->rhs_ = Expression::make_temporary_reference(temp,
this->location());
}
return this;
}
// Add explicit type conversions.
void
Assignment_statement::do_add_conversions()
{
Type* lt = this->lhs_->type();
Type* rt = this->rhs_->type();
if (!Type::are_identical(lt, rt, 0, NULL)
&& lt->interface_type() != NULL)
this->rhs_ = Expression::make_cast(lt, this->rhs_, this->location());
}
// Convert an assignment statement to the backend representation.
Bstatement*
Assignment_statement::do_get_backend(Translate_context* context)
{
if (this->lhs_->is_sink_expression())
{
Bexpression* rhs = this->rhs_->get_backend(context);
Bfunction* bfunction = context->function()->func_value()->get_decl();
return context->backend()->expression_statement(bfunction, rhs);
}
Bexpression* lhs = this->lhs_->get_backend(context);
Expression* conv =
Expression::convert_for_assignment(context->gogo(), this->lhs_->type(),
this->rhs_, this->location());
Bexpression* rhs = conv->get_backend(context);
Bfunction* bfunction = context->function()->func_value()->get_decl();
return context->backend()->assignment_statement(bfunction, lhs, rhs,
this->location());
}
// Dump the AST representation for an assignment statement.
void
Assignment_statement::do_dump_statement(Ast_dump_context* ast_dump_context)
const
{
ast_dump_context->print_indent();
ast_dump_context->dump_expression(this->lhs_);
ast_dump_context->ostream() << " = " ;
ast_dump_context->dump_expression(this->rhs_);
ast_dump_context->ostream() << dsuffix(location()) << std::endl;
}
// Make an assignment statement.
Assignment_statement*
Statement::make_assignment(Expression* lhs, Expression* rhs,
Location location)
{
Temporary_reference_expression* tre = lhs->temporary_reference_expression();
if (tre != NULL)
tre->statement()->set_assigned();
return new Assignment_statement(lhs, rhs, location);
}
// An assignment operation statement.
class Assignment_operation_statement : public Statement
{
public:
Assignment_operation_statement(Operator op, Expression* lhs, Expression* rhs,
Location location)
: Statement(STATEMENT_ASSIGNMENT_OPERATION, location),
op_(op), lhs_(lhs), rhs_(rhs)
{ }
protected:
int
do_traverse(Traverse*);
bool
do_traverse_assignments(Traverse_assignments*)
{ go_unreachable(); }
Statement*
do_lower(Gogo*, Named_object*, Block*, Statement_inserter*);
Bstatement*
do_get_backend(Translate_context*)
{ go_unreachable(); }
void
do_dump_statement(Ast_dump_context*) const;
private:
// The operator (OPERATOR_PLUSEQ, etc.).
Operator op_;
// Left hand side.
Expression* lhs_;
// Right hand side.
Expression* rhs_;
};
// Traversal.
int
Assignment_operation_statement::do_traverse(Traverse* traverse)
{
if (this->traverse_expression(traverse, &this->lhs_) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
return this->traverse_expression(traverse, &this->rhs_);
}
// Lower an assignment operation statement to a regular assignment
// statement.
Statement*
Assignment_operation_statement::do_lower(Gogo*, Named_object*,
Block* enclosing, Statement_inserter*)
{
Location loc = this->location();
// We have to evaluate the left hand side expression only once. We
// do this by moving out any expression with side effects.
Block* b = new Block(enclosing, loc);
Move_ordered_evals moe(b);
this->lhs_->traverse_subexpressions(&moe);
Expression* lval = this->lhs_->copy();
Operator op;
switch (this->op_)
{
case OPERATOR_PLUSEQ:
op = OPERATOR_PLUS;
break;
case OPERATOR_MINUSEQ:
op = OPERATOR_MINUS;
break;
case OPERATOR_OREQ:
op = OPERATOR_OR;
break;
case OPERATOR_XOREQ:
op = OPERATOR_XOR;
break;
case OPERATOR_MULTEQ:
op = OPERATOR_MULT;
break;
case OPERATOR_DIVEQ:
op = OPERATOR_DIV;
break;
case OPERATOR_MODEQ:
op = OPERATOR_MOD;
break;
case OPERATOR_LSHIFTEQ:
op = OPERATOR_LSHIFT;
break;
case OPERATOR_RSHIFTEQ:
op = OPERATOR_RSHIFT;
break;
case OPERATOR_ANDEQ:
op = OPERATOR_AND;
break;
case OPERATOR_BITCLEAREQ:
op = OPERATOR_BITCLEAR;
break;
default:
go_unreachable();
}
Expression* binop = Expression::make_binary(op, lval, this->rhs_, loc);
Statement* s = Statement::make_assignment(this->lhs_, binop, loc);
if (b->statements()->empty())
{
delete b;
return s;
}
else
{
b->add_statement(s);
return Statement::make_block_statement(b, loc);
}
}
// Dump the AST representation for an assignment operation statement
void
Assignment_operation_statement::do_dump_statement(
Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->dump_expression(this->lhs_);
ast_dump_context->dump_operator(this->op_);
ast_dump_context->dump_expression(this->rhs_);
ast_dump_context->ostream() << dsuffix(location()) << std::endl;
}
// Make an assignment operation statement.
Statement*
Statement::make_assignment_operation(Operator op, Expression* lhs,
Expression* rhs, Location location)
{
return new Assignment_operation_statement(op, lhs, rhs, location);
}
// A tuple assignment statement. This differs from an assignment
// statement in that the right-hand-side expressions are evaluated in
// parallel.
class Tuple_assignment_statement : public Statement
{
public:
Tuple_assignment_statement(Expression_list* lhs, Expression_list* rhs,
Location location)
: Statement(STATEMENT_TUPLE_ASSIGNMENT, location),
lhs_(lhs), rhs_(rhs)
{ }
protected:
int
do_traverse(Traverse* traverse);
bool
do_traverse_assignments(Traverse_assignments*)
{ go_unreachable(); }
Statement*
do_lower(Gogo*, Named_object*, Block*, Statement_inserter*);
Bstatement*
do_get_backend(Translate_context*)
{ go_unreachable(); }
void
do_dump_statement(Ast_dump_context*) const;
private:
// Left hand side--a list of lvalues.
Expression_list* lhs_;
// Right hand side--a list of rvalues.
Expression_list* rhs_;
};
// Traversal.
int
Tuple_assignment_statement::do_traverse(Traverse* traverse)
{
if (this->traverse_expression_list(traverse, this->lhs_) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
return this->traverse_expression_list(traverse, this->rhs_);
}
// Lower a tuple assignment. We use temporary variables to split it
// up into a set of single assignments.
Statement*
Tuple_assignment_statement::do_lower(Gogo*, Named_object*, Block* enclosing,
Statement_inserter*)
{
Location loc = this->location();
Block* b = new Block(enclosing, loc);
// First move out any subexpressions on the left hand side. The
// right hand side will be evaluated in the required order anyhow.
Move_ordered_evals moe(b);
for (Expression_list::iterator plhs = this->lhs_->begin();
plhs != this->lhs_->end();
++plhs)
Expression::traverse(&*plhs, &moe);
std::vector<Temporary_statement*> temps;
temps.reserve(this->lhs_->size());
Expression_list::const_iterator prhs = this->rhs_->begin();
for (Expression_list::const_iterator plhs = this->lhs_->begin();
plhs != this->lhs_->end();
++plhs, ++prhs)
{
go_assert(prhs != this->rhs_->end());
if ((*plhs)->is_error_expression()
|| (*plhs)->type()->is_error()
|| (*prhs)->is_error_expression()
|| (*prhs)->type()->is_error())
continue;
if ((*plhs)->is_sink_expression())
{
if ((*prhs)->type()->is_nil_type())
this->report_error(_("use of untyped nil"));
else
b->add_statement(Statement::make_statement(*prhs, true));
continue;
}
Temporary_statement* temp = Statement::make_temporary((*plhs)->type(),
*prhs, loc);
b->add_statement(temp);
temps.push_back(temp);
}
go_assert(prhs == this->rhs_->end());
prhs = this->rhs_->begin();
std::vector<Temporary_statement*>::const_iterator ptemp = temps.begin();
for (Expression_list::const_iterator plhs = this->lhs_->begin();
plhs != this->lhs_->end();
++plhs, ++prhs)
{
if ((*plhs)->is_error_expression()
|| (*plhs)->type()->is_error()
|| (*prhs)->is_error_expression()
|| (*prhs)->type()->is_error())
continue;
if ((*plhs)->is_sink_expression())
continue;
Expression* ref = Expression::make_temporary_reference(*ptemp, loc);
b->add_statement(Statement::make_assignment(*plhs, ref, loc));
++ptemp;
}
go_assert(ptemp == temps.end() || saw_errors());
return Statement::make_block_statement(b, loc);
}
// Dump the AST representation for a tuple assignment statement.
void
Tuple_assignment_statement::do_dump_statement(
Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->dump_expression_list(this->lhs_);
ast_dump_context->ostream() << " = ";
ast_dump_context->dump_expression_list(this->rhs_);
ast_dump_context->ostream() << dsuffix(location()) << std::endl;
}
// Make a tuple assignment statement.
Statement*
Statement::make_tuple_assignment(Expression_list* lhs, Expression_list* rhs,
Location location)
{
return new Tuple_assignment_statement(lhs, rhs, location);
}
// A tuple assignment from a map index expression.
// v, ok = m[k]
class Tuple_map_assignment_statement : public Statement
{
public:
Tuple_map_assignment_statement(Expression* val, Expression* present,
Expression* map_index,
Location location)
: Statement(STATEMENT_TUPLE_MAP_ASSIGNMENT, location),
val_(val), present_(present), map_index_(map_index)
{ }
protected:
int
do_traverse(Traverse* traverse);
bool
do_traverse_assignments(Traverse_assignments*)
{ go_unreachable(); }
Statement*
do_lower(Gogo*, Named_object*, Block*, Statement_inserter*);
Bstatement*
do_get_backend(Translate_context*)
{ go_unreachable(); }
void
do_dump_statement(Ast_dump_context*) const;
private:
// Lvalue which receives the value from the map.
Expression* val_;
// Lvalue which receives whether the key value was present.
Expression* present_;
// The map index expression.
Expression* map_index_;
};
// Traversal.
int
Tuple_map_assignment_statement::do_traverse(Traverse* traverse)
{
if (this->traverse_expression(traverse, &this->val_) == TRAVERSE_EXIT
|| this->traverse_expression(traverse, &this->present_) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
return this->traverse_expression(traverse, &this->map_index_);
}
// Lower a tuple map assignment.
Statement*
Tuple_map_assignment_statement::do_lower(Gogo* gogo, Named_object*,
Block* enclosing, Statement_inserter*)
{
Location loc = this->location();
Map_index_expression* map_index = this->map_index_->map_index_expression();
if (map_index == NULL)
{
this->report_error(_("expected map index on right hand side"));
return Statement::make_error_statement(loc);
}
Map_type* map_type = map_index->get_map_type();
if (map_type == NULL)
return Statement::make_error_statement(loc);
// Avoid copy for string([]byte) conversions used in map keys.
// mapaccess doesn't keep the reference, so this is safe.
Type_conversion_expression* ce = map_index->index()->conversion_expression();
if (ce != NULL && ce->type()->is_string_type()
&& ce->expr()->type()->is_slice_type())
ce->set_no_copy(true);
Block* b = new Block(enclosing, loc);
// Move out any subexpressions to make sure that functions are
// called in the required order.
Move_ordered_evals moe(b);
this->val_->traverse_subexpressions(&moe);
this->present_->traverse_subexpressions(&moe);
// Copy the key value into a temporary so that we can take its
// address without pushing the value onto the heap.
// var key_temp KEY_TYPE = MAP_INDEX
Temporary_statement* key_temp =
Statement::make_temporary(map_type->key_type(), map_index->index(), loc);
b->add_statement(key_temp);
// var val_ptr_temp *VAL_TYPE
Type* val_ptr_type = Type::make_pointer_type(map_type->val_type());
Temporary_statement* val_ptr_temp = Statement::make_temporary(val_ptr_type,
NULL, loc);
b->add_statement(val_ptr_temp);
// var present_temp bool
Temporary_statement* present_temp =
Statement::make_temporary((this->present_->type()->is_sink_type())
? Type::make_boolean_type()
: this->present_->type(),
NULL, loc);
b->add_statement(present_temp);
// val_ptr_temp, present_temp = mapaccess2(DESCRIPTOR, MAP, &key_temp)
Expression* a1 = Expression::make_type_descriptor(map_type, loc);
Expression* a2 = map_index->map();
Temporary_reference_expression* ref =
Expression::make_temporary_reference(key_temp, loc);
Expression* a3 = Expression::make_unary(OPERATOR_AND, ref, loc);
Expression* a4 = map_type->fat_zero_value(gogo);
Call_expression* call;
if (a4 == NULL)
{
Runtime::Function code;
Map_type::Map_alg alg = map_type->algorithm(gogo);
switch (alg)
{
case Map_type::MAP_ALG_FAST32:
case Map_type::MAP_ALG_FAST32PTR:
{
code = Runtime::MAPACCESS2_FAST32;
Type* uint32_type = Type::lookup_integer_type("uint32");
Type* uint32_ptr_type = Type::make_pointer_type(uint32_type);
a3 = Expression::make_unsafe_cast(uint32_ptr_type, a3,
loc);
a3 = Expression::make_dereference(a3,
Expression::NIL_CHECK_NOT_NEEDED,
loc);
break;
}
case Map_type::MAP_ALG_FAST64:
case Map_type::MAP_ALG_FAST64PTR:
{
code = Runtime::MAPACCESS2_FAST64;
Type* uint64_type = Type::lookup_integer_type("uint64");
Type* uint64_ptr_type = Type::make_pointer_type(uint64_type);
a3 = Expression::make_unsafe_cast(uint64_ptr_type, a3,
loc);
a3 = Expression::make_dereference(a3,
Expression::NIL_CHECK_NOT_NEEDED,
loc);
break;
}
case Map_type::MAP_ALG_FASTSTR:
code = Runtime::MAPACCESS2_FASTSTR;
a3 = ref;
break;
default:
code = Runtime::MAPACCESS2;
break;
}
call = Runtime::make_call(code, loc, 3, a1, a2, a3);
}
else
call = Runtime::make_call(Runtime::MAPACCESS2_FAT, loc, 4, a1, a2, a3, a4);
ref = Expression::make_temporary_reference(val_ptr_temp, loc);
ref->set_is_lvalue();
Expression* res = Expression::make_call_result(call, 0);
res = Expression::make_unsafe_cast(val_ptr_type, res, loc);
Statement* s = Statement::make_assignment(ref, res, loc);
b->add_statement(s);
ref = Expression::make_temporary_reference(present_temp, loc);
ref->set_is_lvalue();
res = Expression::make_call_result(call, 1);
s = Statement::make_assignment(ref, res, loc);
b->add_statement(s);
// val = *val__ptr_temp
ref = Expression::make_temporary_reference(val_ptr_temp, loc);
Expression* ind =
Expression::make_dereference(ref, Expression::NIL_CHECK_NOT_NEEDED, loc);
s = Statement::make_assignment(this->val_, ind, loc);
b->add_statement(s);
// present = present_temp
ref = Expression::make_temporary_reference(present_temp, loc);
s = Statement::make_assignment(this->present_, ref, loc);
b->add_statement(s);
return Statement::make_block_statement(b, loc);
}
// Dump the AST representation for a tuple map assignment statement.
void
Tuple_map_assignment_statement::do_dump_statement(
Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->dump_expression(this->val_);
ast_dump_context->ostream() << ", ";
ast_dump_context->dump_expression(this->present_);
ast_dump_context->ostream() << " = ";
ast_dump_context->dump_expression(this->map_index_);
ast_dump_context->ostream() << dsuffix(location()) << std::endl;
}
// Make a map assignment statement which returns a pair of values.
Statement*
Statement::make_tuple_map_assignment(Expression* val, Expression* present,
Expression* map_index,
Location location)
{
return new Tuple_map_assignment_statement(val, present, map_index, location);
}
// A tuple assignment from a receive statement.
class Tuple_receive_assignment_statement : public Statement
{
public:
Tuple_receive_assignment_statement(Expression* val, Expression* closed,
Expression* channel, Location location)
: Statement(STATEMENT_TUPLE_RECEIVE_ASSIGNMENT, location),
val_(val), closed_(closed), channel_(channel)
{ }
protected:
int
do_traverse(Traverse* traverse);
bool
do_traverse_assignments(Traverse_assignments*)
{ go_unreachable(); }
Statement*
do_lower(Gogo*, Named_object*, Block*, Statement_inserter*);
Bstatement*
do_get_backend(Translate_context*)
{ go_unreachable(); }
void
do_dump_statement(Ast_dump_context*) const;
private:
// Lvalue which receives the value from the channel.
Expression* val_;
// Lvalue which receives whether the channel is closed.
Expression* closed_;
// The channel on which we receive the value.
Expression* channel_;
};
// Traversal.
int
Tuple_receive_assignment_statement::do_traverse(Traverse* traverse)
{
if (this->traverse_expression(traverse, &this->val_) == TRAVERSE_EXIT
|| this->traverse_expression(traverse, &this->closed_) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
return this->traverse_expression(traverse, &this->channel_);
}
// Lower to a function call.
Statement*
Tuple_receive_assignment_statement::do_lower(Gogo*, Named_object*,
Block* enclosing,
Statement_inserter*)
{
Location loc = this->location();
Channel_type* channel_type = this->channel_->type()->channel_type();
if (channel_type == NULL)
{
this->report_error(_("expected channel"));
return Statement::make_error_statement(loc);
}
if (!channel_type->may_receive())
{
this->report_error(_("invalid receive on send-only channel"));
return Statement::make_error_statement(loc);
}
Block* b = new Block(enclosing, loc);
// Make sure that any subexpressions on the left hand side are
// evaluated in the right order.
Move_ordered_evals moe(b);
this->val_->traverse_subexpressions(&moe);
this->closed_->traverse_subexpressions(&moe);
// var val_temp ELEMENT_TYPE
Temporary_statement* val_temp =
Statement::make_temporary(channel_type->element_type(), NULL, loc);
b->add_statement(val_temp);
// var closed_temp bool
Temporary_statement* closed_temp =
Statement::make_temporary((this->closed_->type()->is_sink_type())
? Type::make_boolean_type()
: this->closed_->type(),
NULL, loc);
b->add_statement(closed_temp);
// closed_temp = chanrecv2(channel, &val_temp)
Temporary_reference_expression* ref =
Expression::make_temporary_reference(val_temp, loc);
Expression* p2 = Expression::make_unary(OPERATOR_AND, ref, loc);
Expression* call = Runtime::make_call(Runtime::CHANRECV2,
loc, 2, this->channel_, p2);
ref = Expression::make_temporary_reference(closed_temp, loc);
ref->set_is_lvalue();
Statement* s = Statement::make_assignment(ref, call, loc);
b->add_statement(s);
// val = val_temp
ref = Expression::make_temporary_reference(val_temp, loc);
s = Statement::make_assignment(this->val_, ref, loc);
b->add_statement(s);
// closed = closed_temp
ref = Expression::make_temporary_reference(closed_temp, loc);
s = Statement::make_assignment(this->closed_, ref, loc);
b->add_statement(s);
return Statement::make_block_statement(b, loc);
}
// Dump the AST representation for a tuple receive statement.
void
Tuple_receive_assignment_statement::do_dump_statement(
Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->dump_expression(this->val_);
ast_dump_context->ostream() << ", ";
ast_dump_context->dump_expression(this->closed_);
ast_dump_context->ostream() << " <- ";
ast_dump_context->dump_expression(this->channel_);
ast_dump_context->ostream() << dsuffix(location()) << std::endl;
}
// Make a nonblocking receive statement.
Statement*
Statement::make_tuple_receive_assignment(Expression* val, Expression* closed,
Expression* channel,
Location location)
{
return new Tuple_receive_assignment_statement(val, closed, channel,
location);
}
// An assignment to a pair of values from a type guard. This is a
// conditional type guard. v, ok = i.(type).
class Tuple_type_guard_assignment_statement : public Statement
{
public:
Tuple_type_guard_assignment_statement(Expression* val, Expression* ok,
Expression* expr, Type* type,
Location location)
: Statement(STATEMENT_TUPLE_TYPE_GUARD_ASSIGNMENT, location),
val_(val), ok_(ok), expr_(expr), type_(type)
{ }
protected:
int
do_traverse(Traverse*);
bool
do_traverse_assignments(Traverse_assignments*)
{ go_unreachable(); }
Statement*
do_lower(Gogo*, Named_object*, Block*, Statement_inserter*);
Bstatement*
do_get_backend(Translate_context*)
{ go_unreachable(); }
void
do_dump_statement(Ast_dump_context*) const;
private:
Call_expression*
lower_to_type(Runtime::Function);
void
lower_to_object_type(Block*, Runtime::Function);
// The variable which recieves the converted value.
Expression* val_;
// The variable which receives the indication of success.
Expression* ok_;
// The expression being converted.
Expression* expr_;
// The type to which the expression is being converted.
Type* type_;
};
// Traverse a type guard tuple assignment.
int
Tuple_type_guard_assignment_statement::do_traverse(Traverse* traverse)
{
if (this->traverse_expression(traverse, &this->val_) == TRAVERSE_EXIT
|| this->traverse_expression(traverse, &this->ok_) == TRAVERSE_EXIT
|| this->traverse_type(traverse, this->type_) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
return this->traverse_expression(traverse, &this->expr_);
}
// Lower to a function call.
Statement*
Tuple_type_guard_assignment_statement::do_lower(Gogo*, Named_object*,
Block* enclosing,
Statement_inserter*)
{
Location loc = this->location();
Type* expr_type = this->expr_->type();
if (expr_type->interface_type() == NULL)
{
if (!expr_type->is_error() && !this->type_->is_error())
this->report_error(_("type assertion only valid for interface types"));
return Statement::make_error_statement(loc);
}
Block* b = new Block(enclosing, loc);
// Make sure that any subexpressions on the left hand side are
// evaluated in the right order.
Move_ordered_evals moe(b);
this->val_->traverse_subexpressions(&moe);
this->ok_->traverse_subexpressions(&moe);
bool expr_is_empty = expr_type->interface_type()->is_empty();
Call_expression* call;
if (this->type_->interface_type() != NULL)
{
if (this->type_->interface_type()->is_empty())
call = Runtime::make_call((expr_is_empty
? Runtime::IFACEE2E2
: Runtime::IFACEI2E2),
loc, 1, this->expr_);
else
call = this->lower_to_type(expr_is_empty
? Runtime::IFACEE2I2
: Runtime::IFACEI2I2);
}
else if (this->type_->points_to() != NULL)
call = this->lower_to_type(expr_is_empty
? Runtime::IFACEE2T2P
: Runtime::IFACEI2T2P);
else
{
this->lower_to_object_type(b,
(expr_is_empty
? Runtime::IFACEE2T2
: Runtime::IFACEI2T2));
call = NULL;
}
if (call != NULL)
{
Expression* res = Expression::make_call_result(call, 0);
res = Expression::make_unsafe_cast(this->type_, res, loc);
Statement* s = Statement::make_assignment(this->val_, res, loc);
b->add_statement(s);
res = Expression::make_call_result(call, 1);
s = Statement::make_assignment(this->ok_, res, loc);
b->add_statement(s);
}
return Statement::make_block_statement(b, loc);
}
// Lower a conversion to a non-empty interface type or a pointer type.
Call_expression*
Tuple_type_guard_assignment_statement::lower_to_type(Runtime::Function code)
{
Location loc = this->location();
return Runtime::make_call(code, loc, 2,
Expression::make_type_descriptor(this->type_, loc),
this->expr_);
}
// Lower a conversion to a non-interface non-pointer type.
void
Tuple_type_guard_assignment_statement::lower_to_object_type(
Block* b,
Runtime::Function code)
{
Location loc = this->location();
// var val_temp TYPE
Temporary_statement* val_temp = Statement::make_temporary(this->type_,
NULL, loc);
b->add_statement(val_temp);
// var ok_temp bool
Temporary_statement* ok_temp = NULL;
if (!this->ok_->is_sink_expression())
{
ok_temp = Statement::make_temporary(this->ok_->type(),
NULL, loc);
b->add_statement(ok_temp);
}
// ok_temp = CODE(type_descriptor, expr, &val_temp)
Expression* p1 = Expression::make_type_descriptor(this->type_, loc);
Expression* ref = Expression::make_temporary_reference(val_temp, loc);
Expression* p3 = Expression::make_unary(OPERATOR_AND, ref, loc);
Expression* call = Runtime::make_call(code, loc, 3, p1, this->expr_, p3);
Statement* s;
if (ok_temp == NULL)
s = Statement::make_statement(call, true);
else
{
Expression* ok_ref = Expression::make_temporary_reference(ok_temp, loc);
s = Statement::make_assignment(ok_ref, call, loc);
}
b->add_statement(s);
// val = val_temp
ref = Expression::make_temporary_reference(val_temp, loc);
s = Statement::make_assignment(this->val_, ref, loc);
b->add_statement(s);
// ok = ok_temp
if (ok_temp != NULL)
{
ref = Expression::make_temporary_reference(ok_temp, loc);
s = Statement::make_assignment(this->ok_, ref, loc);
b->add_statement(s);
}
}
// Dump the AST representation for a tuple type guard statement.
void
Tuple_type_guard_assignment_statement::do_dump_statement(
Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->dump_expression(this->val_);
ast_dump_context->ostream() << ", ";
ast_dump_context->dump_expression(this->ok_);
ast_dump_context->ostream() << " = ";
ast_dump_context->dump_expression(this->expr_);
ast_dump_context->ostream() << " . ";
ast_dump_context->dump_type(this->type_);
ast_dump_context->ostream() << dsuffix(location()) << std::endl;
}
// Make an assignment from a type guard to a pair of variables.
Statement*
Statement::make_tuple_type_guard_assignment(Expression* val, Expression* ok,
Expression* expr, Type* type,
Location location)
{
return new Tuple_type_guard_assignment_statement(val, ok, expr, type,
location);
}
// Class Expression_statement.
// Constructor.
Expression_statement::Expression_statement(Expression* expr, bool is_ignored)
: Statement(STATEMENT_EXPRESSION, expr->location()),
expr_(expr), is_ignored_(is_ignored)
{
}
// Determine types.
void
Expression_statement::do_determine_types()
{
this->expr_->determine_type_no_context();
}
// Check the types of an expression statement. The only check we do
// is to possibly give an error about discarding the value of the
// expression.
void
Expression_statement::do_check_types(Gogo*)
{
if (!this->is_ignored_)
this->expr_->discarding_value();
}
// An expression statement is only a terminating statement if it is
// a call to panic.
bool
Expression_statement::do_may_fall_through() const
{
const Call_expression* call = this->expr_->call_expression();
if (call != NULL)
{
const Expression* fn = call->fn();
// panic is still an unknown named object.
const Unknown_expression* ue = fn->unknown_expression();
if (ue != NULL)
{
Named_object* no = ue->named_object();
if (no->is_unknown())
no = no->unknown_value()->real_named_object();
if (no != NULL)
{
Function_type* fntype;
if (no->is_function())
fntype = no->func_value()->type();
else if (no->is_function_declaration())
fntype = no->func_declaration_value()->type();
else
fntype = NULL;
// The builtin function panic does not return.
if (fntype != NULL && fntype->is_builtin() && no->name() == "panic")
return false;
}
}
}
return true;
}
// Export an expression statement.
void
Expression_statement::do_export_statement(Export_function_body* efb)
{
this->expr_->export_expression(efb);
}
// Convert to backend representation.
Bstatement*
Expression_statement::do_get_backend(Translate_context* context)
{
Bexpression* bexpr = this->expr_->get_backend(context);
Bfunction* bfunction = context->function()->func_value()->get_decl();
return context->backend()->expression_statement(bfunction, bexpr);
}
// Dump the AST representation for an expression statement
void
Expression_statement::do_dump_statement(Ast_dump_context* ast_dump_context)
const
{
ast_dump_context->print_indent();
ast_dump_context->dump_expression(expr_);
ast_dump_context->ostream() << dsuffix(location()) << std::endl;
}
// Make an expression statement from an Expression.
Statement*
Statement::make_statement(Expression* expr, bool is_ignored)
{
return new Expression_statement(expr, is_ignored);
}
// Export data for a block.
void
Block_statement::do_export_statement(Export_function_body* efb)
{
Block_statement::export_block(efb, this->block_,
this->is_lowered_for_statement_);
}
void
Block_statement::export_block(Export_function_body* efb, Block* block,
bool is_lowered_for_statement)
{
// We are already indented to the right position.
char buf[50];
efb->write_c_string("{");
if (is_lowered_for_statement)
efb->write_c_string(" /*for*/");
snprintf(buf, sizeof buf, " //%d\n",
Linemap::location_to_line(block->start_location()));
efb->write_c_string(buf);
block->export_block(efb);
// The indentation is correct for the statements in the block, so
// subtract one for the closing curly brace.
efb->decrement_indent();
efb->indent();
efb->write_c_string("}");
// Increment back to the value the caller thinks it has.
efb->increment_indent();
}
// Import a block statement, returning the block.
Block*
Block_statement::do_import(Import_function_body* ifb, Location loc,
bool* is_lowered_for_statement)
{
go_assert(ifb->match_c_string("{"));
*is_lowered_for_statement = false;
if (ifb->match_c_string(" /*for*/"))
{
ifb->advance(8);
*is_lowered_for_statement = true;
}
size_t nl = ifb->body().find('\n', ifb->off());
if (nl == std::string::npos)
{
if (!ifb->saw_error())
go_error_at(ifb->location(),
"import error: no newline after %<{%> at %lu",
static_cast<unsigned long>(ifb->off()));
ifb->set_saw_error();
return NULL;
}
ifb->set_off(nl + 1);
ifb->increment_indent();
Block* block = new Block(ifb->block(), loc);
ifb->begin_block(block);
bool ok = Block::import_block(block, ifb, loc);
ifb->finish_block();
ifb->decrement_indent();
if (!ok)
return NULL;
return block;
}
// Convert a block to the backend representation of a statement.
Bstatement*
Block_statement::do_get_backend(Translate_context* context)
{
Bblock* bblock = this->block_->get_backend(context);
return context->backend()->block_statement(bblock);
}
// Dump the AST for a block statement
void
Block_statement::do_dump_statement(Ast_dump_context*) const
{
// block statement braces are dumped when traversing.
}
// Make a block statement.
Block_statement*
Statement::make_block_statement(Block* block, Location location)
{
return new Block_statement(block, location);
}
// An increment or decrement statement.
class Inc_dec_statement : public Statement
{
public:
Inc_dec_statement(bool is_inc, Expression* expr)
: Statement(STATEMENT_INCDEC, expr->location()),
expr_(expr), is_inc_(is_inc)
{ }
protected:
int
do_traverse(Traverse* traverse)
{ return this->traverse_expression(traverse, &this->expr_); }
bool
do_traverse_assignments(Traverse_assignments*)
{ go_unreachable(); }
Statement*
do_lower(Gogo*, Named_object*, Block*, Statement_inserter*);
Bstatement*
do_get_backend(Translate_context*)
{ go_unreachable(); }
void
do_dump_statement(Ast_dump_context*) const;
private:
// The l-value to increment or decrement.
Expression* expr_;
// Whether to increment or decrement.
bool is_inc_;
};
// Lower to += or -=.
Statement*
Inc_dec_statement::do_lower(Gogo*, Named_object*, Block*, Statement_inserter*)
{
Location loc = this->location();
if (!this->expr_->type()->is_numeric_type())
{
this->report_error("increment or decrement of non-numeric type");
return Statement::make_error_statement(loc);
}
Expression* oexpr = Expression::make_integer_ul(1, this->expr_->type(), loc);
Operator op = this->is_inc_ ? OPERATOR_PLUSEQ : OPERATOR_MINUSEQ;
return Statement::make_assignment_operation(op, this->expr_, oexpr, loc);
}
// Dump the AST representation for a inc/dec statement.
void
Inc_dec_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->dump_expression(expr_);
ast_dump_context->ostream() << (is_inc_? "++": "--") << dsuffix(location()) << std::endl;
}
// Make an increment statement.
Statement*
Statement::make_inc_statement(Expression* expr)
{
return new Inc_dec_statement(true, expr);
}
// Make a decrement statement.
Statement*
Statement::make_dec_statement(Expression* expr)
{
return new Inc_dec_statement(false, expr);
}
// Class Thunk_statement. This is the base class for go and defer
// statements.
// Constructor.
Thunk_statement::Thunk_statement(Statement_classification classification,
Call_expression* call,
Location location)
: Statement(classification, location),
call_(call), struct_type_(NULL)
{
}
// Return whether this is a simple statement which does not require a
// thunk.
bool
Thunk_statement::is_simple(Function_type* fntype) const
{
// We need a thunk to call a method, or to pass a variable number of
// arguments.
if (fntype->is_method() || fntype->is_varargs())
return false;
// A defer statement requires a thunk to set up for whether the
// function can call recover.
if (this->classification() == STATEMENT_DEFER)
return false;
// We can only permit a single parameter of pointer type.
const Typed_identifier_list* parameters = fntype->parameters();
if (parameters != NULL
&& (parameters->size() > 1
|| (parameters->size() == 1
&& parameters->begin()->type()->points_to() == NULL)))
return false;
// If the function returns multiple values, or returns a type other
// than integer, floating point, or pointer, then it may get a
// hidden first parameter, in which case we need the more
// complicated approach. This is true even though we are going to
// ignore the return value.
const Typed_identifier_list* results = fntype->results();
if (results != NULL
&& (results->size() > 1
|| (results->size() == 1
&& !results->begin()->type()->is_basic_type()
&& results->begin()->type()->points_to() == NULL)))
return false;
// If this calls something that is not a simple function, then we
// need a thunk.
Expression* fn = this->call_->call_expression()->fn();
if (fn->func_expression() == NULL)
return false;
// If the function uses a closure, then we need a thunk. FIXME: We
// could accept a zero argument function with a closure.
if (fn->func_expression()->closure() != NULL)
return false;
return true;
}
// Traverse a thunk statement.
int
Thunk_statement::do_traverse(Traverse* traverse)
{
return this->traverse_expression(traverse, &this->call_);
}
// We implement traverse_assignment for a thunk statement because it
// effectively copies the function call.
bool
Thunk_statement::do_traverse_assignments(Traverse_assignments* tassign)
{
Expression* fn = this->call_->call_expression()->fn();
Expression* fn2 = fn;
tassign->value(&fn2, true, false);
return true;
}
// Determine types in a thunk statement.
void
Thunk_statement::do_determine_types()
{
this->call_->determine_type_no_context();
// Now that we know the types of the call, build the struct used to
// pass parameters.
Call_expression* ce = this->call_->call_expression();
if (ce == NULL)
return;
Function_type* fntype = ce->get_function_type();
if (fntype != NULL && !this->is_simple(fntype))
this->struct_type_ = this->build_struct(fntype);
}
// Check types in a thunk statement.
void
Thunk_statement::do_check_types(Gogo*)
{
if (!this->call_->discarding_value())
return;
Call_expression* ce = this->call_->call_expression();
if (ce == NULL)
{
if (!this->call_->is_error_expression())
this->report_error("expected call expression");
return;
}
}
// The Traverse class used to find and simplify thunk statements.
class Simplify_thunk_traverse : public Traverse
{
public:
Simplify_thunk_traverse(Gogo* gogo)
: Traverse(traverse_functions | traverse_blocks),
gogo_(gogo), function_(NULL)
{ }
int
function(Named_object*);
int
block(Block*);
private:
// General IR.
Gogo* gogo_;
// The function we are traversing.
Named_object* function_;
};
// Keep track of the current function while looking for thunks.
int
Simplify_thunk_traverse::function(Named_object* no)
{
go_assert(this->function_ == NULL);
this->function_ = no;
int t = no->func_value()->traverse(this);
this->function_ = NULL;
if (t == TRAVERSE_EXIT)
return t;
return TRAVERSE_SKIP_COMPONENTS;
}
// Look for thunks in a block.
int
Simplify_thunk_traverse::block(Block* b)
{
// The parser ensures that thunk statements always appear at the end
// of a block.
if (b->statements()->size() < 1)
return TRAVERSE_CONTINUE;
Thunk_statement* stat = b->statements()->back()->thunk_statement();
if (stat == NULL)
return TRAVERSE_CONTINUE;
if (stat->simplify_statement(this->gogo_, this->function_, b))
return TRAVERSE_SKIP_COMPONENTS;
return TRAVERSE_CONTINUE;
}
// Simplify all thunk statements.
void
Gogo::simplify_thunk_statements()
{
Simplify_thunk_traverse thunk_traverse(this);
this->traverse(&thunk_traverse);
}
// Return true if the thunk function is a constant, which means that
// it does not need to be passed to the thunk routine.
bool
Thunk_statement::is_constant_function() const
{
Call_expression* ce = this->call_->call_expression();
Function_type* fntype = ce->get_function_type();
if (fntype == NULL)
{
go_assert(saw_errors());
return false;
}
if (fntype->is_builtin())
return true;
Expression* fn = ce->fn();
if (fn->func_expression() != NULL)
return fn->func_expression()->closure() == NULL;
if (fn->interface_field_reference_expression() != NULL)
return true;
return false;
}
// Simplify complex thunk statements into simple ones. A complicated
// thunk statement is one which takes anything other than zero
// parameters or a single pointer parameter. We rewrite it into code
// which allocates a struct, stores the parameter values into the
// struct, and does a simple go or defer statement which passes the
// struct to a thunk. The thunk does the real call.
bool
Thunk_statement::simplify_statement(Gogo* gogo, Named_object* function,
Block* block)
{
if (this->classification() == STATEMENT_ERROR)
return false;
if (this->call_->is_error_expression())
return false;
if (this->classification() == STATEMENT_DEFER)
{
// Make sure that the defer stack exists for the function. We
// will use when converting this statement to the backend
// representation, but we want it to exist when we start
// converting the function.
function->func_value()->defer_stack(this->location());
}
Call_expression* ce = this->call_->call_expression();
Function_type* fntype = ce->get_function_type();
if (fntype == NULL)
{
go_assert(saw_errors());
this->set_is_error();
return false;
}
if (this->is_simple(fntype))
return false;
Expression* fn = ce->fn();
Interface_field_reference_expression* interface_method =
fn->interface_field_reference_expression();
Location location = this->location();
bool is_constant_function = this->is_constant_function();
Temporary_statement* fn_temp = NULL;
if (!is_constant_function)
{
fn_temp = Statement::make_temporary(NULL, fn, location);
block->insert_statement_before(block->statements()->size() - 1, fn_temp);
fn = Expression::make_temporary_reference(fn_temp, location);
}
std::string thunk_name = gogo->thunk_name();
// Build the thunk.
this->build_thunk(gogo, thunk_name);
// Generate code to call the thunk.
// Get the values to store into the struct which is the single
// argument to the thunk.
Expression_list* vals = new Expression_list();
if (!is_constant_function)
vals->push_back(fn);
if (interface_method != NULL)
vals->push_back(interface_method->expr());
if (ce->args() != NULL)
{
for (Expression_list::const_iterator p = ce->args()->begin();
p != ce->args()->end();
++p)
{
if ((*p)->is_constant())
continue;
vals->push_back(*p);
}
}
// Build the struct.
Expression* constructor =
Expression::make_struct_composite_literal(this->struct_type_, vals,
location);
// Allocate the initialized struct on the heap.
constructor = Expression::make_heap_expression(constructor, location);
if ((Node::make_node(this)->encoding() & ESCAPE_MASK) == Node::ESCAPE_NONE)
constructor->heap_expression()->set_allocate_on_stack();
// Throw an error if the function is nil. This is so that for `go
// nil` we get a backtrace from the go statement, rather than a
// useless backtrace from the brand new goroutine.
Expression* param = constructor;
if (!is_constant_function && this->classification() == STATEMENT_GO)
{
fn = Expression::make_temporary_reference(fn_temp, location);
Expression* nil = Expression::make_nil(location);
Expression* isnil = Expression::make_binary(OPERATOR_EQEQ, fn, nil,
location);
Expression* crash = Runtime::make_call(Runtime::PANIC_GO_NIL,
location, 0);
crash = Expression::make_conditional(isnil, crash,
Expression::make_nil(location),
location);
param = Expression::make_compound(crash, constructor, location);
}
// Look up the thunk.
Named_object* named_thunk = gogo->lookup(thunk_name, NULL);
go_assert(named_thunk != NULL && named_thunk->is_function());
// Build the call.
Expression* func = Expression::make_func_reference(named_thunk, NULL,
location);
Expression_list* params = new Expression_list();
params->push_back(param);
Call_expression* call = Expression::make_call(func, params, false, location);
// Build the simple go or defer statement.
Statement* s;
if (this->classification() == STATEMENT_GO)
s = Statement::make_go_statement(call, location);
else if (this->classification() == STATEMENT_DEFER)
{
s = Statement::make_defer_statement(call, location);
if ((Node::make_node(this)->encoding() & ESCAPE_MASK) == Node::ESCAPE_NONE)
s->defer_statement()->set_on_stack();
}
else
go_unreachable();
// The current block should end with the go statement.
go_assert(block->statements()->size() >= 1);
go_assert(block->statements()->back() == this);
block->replace_statement(block->statements()->size() - 1, s);
// We already ran the determine_types pass, so we need to run it now
// for the new statement.
s->determine_types();
// Sanity check.
gogo->check_types_in_block(block);
// Return true to tell the block not to keep looking at statements.
return true;
}
// Set the name to use for thunk parameter N.
void
Thunk_statement::thunk_field_param(int n, char* buf, size_t buflen)
{
snprintf(buf, buflen, "a%d", n);
}
// Build a new struct type to hold the parameters for a complicated
// thunk statement. FNTYPE is the type of the function call.
Struct_type*
Thunk_statement::build_struct(Function_type* fntype)
{
Location location = this->location();
Struct_field_list* fields = new Struct_field_list();
Call_expression* ce = this->call_->call_expression();
Expression* fn = ce->fn();
if (!this->is_constant_function())
{
// The function to call.
fields->push_back(Struct_field(Typed_identifier("fn", fntype,
location)));
}
// If this thunk statement calls a method on an interface, we pass
// the interface object to the thunk.
Interface_field_reference_expression* interface_method =
fn->interface_field_reference_expression();
if (interface_method != NULL)
{
Typed_identifier tid("object", interface_method->expr()->type(),
location);
fields->push_back(Struct_field(tid));
}
// The predeclared recover function has no argument. However, we
// add an argument when building recover thunks. Handle that here.
if (ce->is_recover_call())
{
fields->push_back(Struct_field(Typed_identifier("can_recover",
Type::lookup_bool_type(),
location)));
}
const Expression_list* args = ce->args();
if (args != NULL)
{
int i = 0;
for (Expression_list::const_iterator p = args->begin();
p != args->end();
++p, ++i)
{
if ((*p)->is_constant())
continue;
char buf[50];
this->thunk_field_param(i, buf, sizeof buf);
fields->push_back(Struct_field(Typed_identifier(buf, (*p)->type(),
location)));
}
}
Struct_type *st = Type::make_struct_type(fields, location);
st->set_is_struct_incomparable();
return st;
}
// Build the thunk we are going to call. This is a brand new, albeit
// artificial, function.
void
Thunk_statement::build_thunk(Gogo* gogo, const std::string& thunk_name)
{
Location location = this->location();
Call_expression* ce = this->call_->call_expression();
bool may_call_recover = false;
if (this->classification() == STATEMENT_DEFER)
{
Func_expression* fn = ce->fn()->func_expression();
if (fn == NULL)
may_call_recover = true;
else
{
const Named_object* no = fn->named_object();
if (!no->is_function())
may_call_recover = true;
else
may_call_recover = no->func_value()->calls_recover();
}
}
// Build the type of the thunk. The thunk takes a single parameter,
// which is a pointer to the special structure we build.
const char* const parameter_name = "__go_thunk_parameter";
Typed_identifier_list* thunk_parameters = new Typed_identifier_list();
Type* pointer_to_struct_type = Type::make_pointer_type(this->struct_type_);
thunk_parameters->push_back(Typed_identifier(parameter_name,
pointer_to_struct_type,
location));
Typed_identifier_list* thunk_results = NULL;
if (may_call_recover)
{
// When deferring a function which may call recover, add a
// return value, to disable tail call optimizations which will
// break the way we check whether recover is permitted.
thunk_results = new Typed_identifier_list();
thunk_results->push_back(Typed_identifier("", Type::lookup_bool_type(),
location));
}
Function_type* thunk_type = Type::make_function_type(NULL, thunk_parameters,
thunk_results,
location);
// Start building the thunk.
Named_object* function = gogo->start_function(thunk_name, thunk_type, true,
location);
gogo->start_block(location);
// For a defer statement, start with a call to
// __go_set_defer_retaddr. */
Label* retaddr_label = NULL;
if (may_call_recover)
{
retaddr_label = gogo->add_label_reference("retaddr", location, false);
Expression* arg = Expression::make_label_addr(retaddr_label, location);
Expression* call = Runtime::make_call(Runtime::SETDEFERRETADDR,
location, 1, arg);
// This is a hack to prevent the middle-end from deleting the
// label.
gogo->start_block(location);
gogo->add_statement(Statement::make_goto_statement(retaddr_label,
location));
Block* then_block = gogo->finish_block(location);
then_block->determine_types();
Statement* s = Statement::make_if_statement(call, then_block, NULL,
location);
s->determine_types();
gogo->add_statement(s);
function->func_value()->set_calls_defer_retaddr();
}
// Get a reference to the parameter.
Named_object* named_parameter = gogo->lookup(parameter_name, NULL);
go_assert(named_parameter != NULL && named_parameter->is_variable());
// Build the call. Note that the field names are the same as the
// ones used in build_struct.
Expression* thunk_parameter = Expression::make_var_reference(named_parameter,
location);
thunk_parameter =
Expression::make_dereference(thunk_parameter,
Expression::NIL_CHECK_NOT_NEEDED,
location);
Interface_field_reference_expression* interface_method =
ce->fn()->interface_field_reference_expression();
Expression* func_to_call;
unsigned int next_index;
if (this->is_constant_function())
{
func_to_call = ce->fn();
next_index = 0;
}
else
{
func_to_call = Expression::make_field_reference(thunk_parameter,
0, location);
next_index = 1;
}
if (interface_method != NULL)
{
// The main program passes the interface object.
go_assert(next_index == 0);
Expression* r = Expression::make_field_reference(thunk_parameter, 0,
location);
const std::string& name(interface_method->name());
func_to_call = Expression::make_interface_field_reference(r, name,
location);
next_index = 1;
}
Expression_list* call_params = new Expression_list();
const Struct_field_list* fields = this->struct_type_->fields();
Struct_field_list::const_iterator p = fields->begin();
for (unsigned int i = 0; i < next_index; ++i)
++p;
bool is_recover_call = ce->is_recover_call();
Expression* recover_arg = NULL;
const Expression_list* args = ce->args();
if (args != NULL)
{
for (Expression_list::const_iterator arg = args->begin();
arg != args->end();
++arg)
{
Expression* param;
if ((*arg)->is_constant())
param = *arg;
else
{
Expression* thunk_param =
Expression::make_var_reference(named_parameter, location);
thunk_param =
Expression::make_dereference(thunk_param,
Expression::NIL_CHECK_NOT_NEEDED,
location);
param = Expression::make_field_reference(thunk_param,
next_index,
location);
++next_index;
}
if (!is_recover_call)
call_params->push_back(param);
else
{
go_assert(call_params->empty());
recover_arg = param;
}
}
}
if (call_params->empty())
{
delete call_params;
call_params = NULL;
}
Call_expression* call = Expression::make_call(func_to_call, call_params,
false, location);
// This call expression was already lowered before entering the
// thunk statement. Don't try to lower varargs again, as that will
// cause confusion for, e.g., method calls which already have a
// receiver parameter.
call->set_varargs_are_lowered();
Statement* call_statement = Statement::make_statement(call, true);
gogo->add_statement(call_statement);
// If this is a defer statement, the label comes immediately after
// the call.
if (may_call_recover)
{
gogo->add_label_definition("retaddr", location);
Expression_list* vals = new Expression_list();
vals->push_back(Expression::make_boolean(false, location));
gogo->add_statement(Statement::make_return_statement(vals, location));
}
Block* b = gogo->finish_block(location);
gogo->add_block(b, location);
gogo->lower_block(function, b);
// We already ran the determine_types pass, so we need to run it
// just for the call statement now. The other types are known.
call_statement->determine_types();
gogo->add_conversions_in_block(b);
if (may_call_recover
|| recover_arg != NULL
|| this->classification() == STATEMENT_GO)
{
// Dig up the call expression, which may have been changed
// during lowering.
go_assert(call_statement->classification() == STATEMENT_EXPRESSION);
Expression_statement* es =
static_cast<Expression_statement*>(call_statement);
ce = es->expr()->call_expression();
if (ce == NULL)
go_assert(saw_errors());
else
{
if (may_call_recover)
ce->set_is_deferred();
if (this->classification() == STATEMENT_GO)
ce->set_is_concurrent();
if (recover_arg != NULL)
ce->set_recover_arg(recover_arg);
}
}
gogo->flatten_block(function, b);
// That is all the thunk has to do.
gogo->finish_function(location);
}
// Get the function and argument expressions.
bool
Thunk_statement::get_fn_and_arg(Expression** pfn, Expression** parg)
{
if (this->call_->is_error_expression())
return false;
Call_expression* ce = this->call_->call_expression();
Expression* fn = ce->fn();
Func_expression* fe = fn->func_expression();
go_assert(fe != NULL);
*pfn = Expression::make_func_code_reference(fe->named_object(),
fe->location());
const Expression_list* args = ce->args();
if (args == NULL || args->empty())
*parg = Expression::make_nil(this->location());
else
{
go_assert(args->size() == 1);
*parg = args->front();
}
return true;
}
// Class Go_statement.
Bstatement*
Go_statement::do_get_backend(Translate_context* context)
{
Expression* fn;
Expression* arg;
if (!this->get_fn_and_arg(&fn, &arg))
return context->backend()->error_statement();
Expression* call = Runtime::make_call(Runtime::GO, this->location(), 2,
fn, arg);
Bexpression* bcall = call->get_backend(context);
Bfunction* bfunction = context->function()->func_value()->get_decl();
return context->backend()->expression_statement(bfunction, bcall);
}
// Dump the AST representation for go statement.
void
Go_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->ostream() << "go ";
ast_dump_context->dump_expression(this->call());
ast_dump_context->ostream() << dsuffix(location()) << std::endl;
}
// Make a go statement.
Statement*
Statement::make_go_statement(Call_expression* call, Location location)
{
return new Go_statement(call, location);
}
// Class Defer_statement.
Bstatement*
Defer_statement::do_get_backend(Translate_context* context)
{
Expression* fn;
Expression* arg;
if (!this->get_fn_and_arg(&fn, &arg))
return context->backend()->error_statement();
Location loc = this->location();
Expression* ds = context->function()->func_value()->defer_stack(loc);
Expression* call;
if (this->on_stack_)
{
if (context->gogo()->debug_optimization())
go_debug(loc, "stack allocated defer");
Type* defer_type = Defer_statement::defer_struct_type();
Expression* defer = Expression::make_allocation(defer_type, loc);
defer->allocation_expression()->set_allocate_on_stack();
defer->allocation_expression()->set_no_zero();
call = Runtime::make_call(Runtime::DEFERPROCSTACK, loc, 4,
defer, ds, fn, arg);
}
else
call = Runtime::make_call(Runtime::DEFERPROC, loc, 3,
ds, fn, arg);
Bexpression* bcall = call->get_backend(context);
Bfunction* bfunction = context->function()->func_value()->get_decl();
return context->backend()->expression_statement(bfunction, bcall);
}
Type*
Defer_statement::defer_struct_type()
{
Type* ptr_type = Type::make_pointer_type(Type::make_void_type());
Type* uintptr_type = Type::lookup_integer_type("uintptr");
Type* bool_type = Type::make_boolean_type();
return Type::make_builtin_struct_type(9,
"link", ptr_type,
"frame", ptr_type,
"panicStack", ptr_type,
"_panic", ptr_type,
"pfn", uintptr_type,
"arg", ptr_type,
"retaddr", uintptr_type,
"makefunccanrecover", bool_type,
"heap", bool_type);
}
// Dump the AST representation for defer statement.
void
Defer_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->ostream() << "defer ";
ast_dump_context->dump_expression(this->call());
ast_dump_context->ostream() << dsuffix(location()) << std::endl;
}
// Make a defer statement.
Statement*
Statement::make_defer_statement(Call_expression* call,
Location location)
{
return new Defer_statement(call, location);
}
// Class Return_statement.
// Traverse assignments. We treat each return value as a top level
// RHS in an expression.
bool
Return_statement::do_traverse_assignments(Traverse_assignments* tassign)
{
Expression_list* vals = this->vals_;
if (vals != NULL)
{
for (Expression_list::iterator p = vals->begin();
p != vals->end();
++p)
tassign->value(&*p, true, true);
}
return true;
}
// Lower a return statement. If we are returning a function call
// which returns multiple values which match the current function,
// split up the call's results. If the return statement lists
// explicit values, implement this statement by assigning the values
// to the result variables and change this statement to a naked
// return. This lets panic/recover work correctly.
Statement*
Return_statement::do_lower(Gogo*, Named_object* function, Block* enclosing,
Statement_inserter*)
{
if (this->is_lowered_)
return this;
Expression_list* vals = this->vals_;
this->vals_ = NULL;
this->is_lowered_ = true;
Location loc = this->location();
size_t vals_count = vals == NULL ? 0 : vals->size();
Function::Results* results = function->func_value()->result_variables();
size_t results_count = results == NULL ? 0 : results->size();
if (vals_count == 0)
{
if (results_count > 0 && !function->func_value()->results_are_named())
{
this->report_error(_("not enough arguments to return"));
return this;
}
return this;
}
if (results_count == 0)
{
this->report_error(_("return with value in function "
"with no return type"));
return this;
}
// If the current function has multiple return values, and we are
// returning a single call expression, split up the call expression.
if (results_count > 1
&& vals->size() == 1
&& vals->front()->call_expression() != NULL)
{
Call_expression* call = vals->front()->call_expression();
call->set_expected_result_count(results_count);
delete vals;
vals = new Expression_list;
for (size_t i = 0; i < results_count; ++i)
vals->push_back(Expression::make_call_result(call, i));
vals_count = results_count;
}
if (vals_count < results_count)
{
this->report_error(_("not enough arguments to return"));
return this;
}
if (vals_count > results_count)
{
this->report_error(_("too many values in return statement"));
return this;
}
Block* b = new Block(enclosing, loc);
Expression_list* lhs = new Expression_list();
Expression_list* rhs = new Expression_list();
Expression_list::const_iterator pe = vals->begin();
int i = 1;
for (Function::Results::const_iterator pr = results->begin();
pr != results->end();
++pr, ++pe, ++i)
{
Named_object* rv = *pr;
Expression* e = *pe;
// Check types now so that we give a good error message. The
// result type is known. We determine the expression type
// early.
Type *rvtype = rv->result_var_value()->type();
Type_context type_context(rvtype, false);
e->determine_type(&type_context);
std::string reason;
if (Type::are_assignable(rvtype, e->type(), &reason))
{
Expression* ve = Expression::make_var_reference(rv, e->location());
lhs->push_back(ve);
rhs->push_back(e);
}
else
{
if (reason.empty())
go_error_at(e->location(),
"incompatible type for return value %d", i);
else
go_error_at(e->location(),
"incompatible type for return value %d (%s)",
i, reason.c_str());
}
}
go_assert(lhs->size() == rhs->size());
if (lhs->empty())
;
else if (lhs->size() == 1)
{
b->add_statement(Statement::make_assignment(lhs->front(), rhs->front(),
loc));
delete lhs;
delete rhs;
}
else
b->add_statement(Statement::make_tuple_assignment(lhs, rhs, loc));
b->add_statement(this);
delete vals;
return Statement::make_block_statement(b, loc);
}
// Convert a return statement to the backend representation.
Bstatement*
Return_statement::do_get_backend(Translate_context* context)
{
Location loc = this->location();
Function* function = context->function()->func_value();
Function::Results* results = function->result_variables();
std::vector<Bexpression*> retvals;
if (results != NULL && !results->empty())
{
retvals.reserve(results->size());
for (Function::Results::const_iterator p = results->begin();
p != results->end();
p++)
{
Expression* vr = Expression::make_var_reference(*p, loc);
retvals.push_back(vr->get_backend(context));
}
}
return context->backend()->return_statement(function->get_decl(),
retvals, loc);
}
// Export a return statement. At this point all the expressions have
// been converted to assignments to the result variables, so this is
// simple.
void
Return_statement::do_export_statement(Export_function_body* efb)
{
efb->write_c_string("return");
}
// Dump the AST representation for a return statement.
void
Return_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->ostream() << "return " ;
ast_dump_context->dump_expression_list(this->vals_);
ast_dump_context->ostream() << dsuffix(location()) << std::endl;
}
// Make a return statement.
Return_statement*
Statement::make_return_statement(Expression_list* vals,
Location location)
{
return new Return_statement(vals, location);
}
// Make a statement that returns the result of a call expression.
Statement*
Statement::make_return_from_call(Call_expression* call, Location location)
{
size_t rc = call->result_count();
if (rc == 0)
return Statement::make_statement(call, true);
else
{
Expression_list* vals = new Expression_list();
if (rc == 1)
vals->push_back(call);
else
{
for (size_t i = 0; i < rc; ++i)
vals->push_back(Expression::make_call_result(call, i));
}
return Statement::make_return_statement(vals, location);
}
}
// A break or continue statement.
class Bc_statement : public Statement
{
public:
Bc_statement(bool is_break, Unnamed_label* label, Location location)
: Statement(STATEMENT_BREAK_OR_CONTINUE, location),
label_(label), is_break_(is_break)
{ }
bool
is_break() const
{ return this->is_break_; }
protected:
int
do_traverse(Traverse*)
{ return TRAVERSE_CONTINUE; }
bool
do_may_fall_through() const
{ return false; }
Bstatement*
do_get_backend(Translate_context* context)
{ return this->label_->get_goto(context, this->location()); }
void
do_dump_statement(Ast_dump_context*) const;
private:
// The label that this branches to.
Unnamed_label* label_;
// True if this is "break", false if it is "continue".
bool is_break_;
};
// Dump the AST representation for a break/continue statement
void
Bc_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->ostream() << (this->is_break_ ? "break" : "continue");
if (this->label_ != NULL)
{
ast_dump_context->ostream() << " ";
ast_dump_context->dump_label_name(this->label_);
}
ast_dump_context->ostream() << dsuffix(location()) << std::endl;
}
// Make a break statement.
Statement*
Statement::make_break_statement(Unnamed_label* label, Location location)
{
return new Bc_statement(true, label, location);
}
// Make a continue statement.
Statement*
Statement::make_continue_statement(Unnamed_label* label,
Location location)
{
return new Bc_statement(false, label, location);
}
// Class Goto_statement.
int
Goto_statement::do_traverse(Traverse*)
{
return TRAVERSE_CONTINUE;
}
// Check types for a label. There aren't any types per se, but we use
// this to give an error if the label was never defined.
void
Goto_statement::do_check_types(Gogo*)
{
if (!this->label_->is_defined())
{
go_error_at(this->location(), "reference to undefined label %qs",
Gogo::message_name(this->label_->name()).c_str());
this->set_is_error();
}
}
// Convert the goto statement to the backend representation.
Bstatement*
Goto_statement::do_get_backend(Translate_context* context)
{
Blabel* blabel = this->label_->get_backend_label(context);
return context->backend()->goto_statement(blabel, this->location());
}
// Export a goto statement.
void
Goto_statement::do_export_statement(Export_function_body *efb)
{
efb->write_c_string("goto ");
efb->write_string(this->label_->name());
}
// Import a goto or goto unnamed statement.
Statement*
Goto_statement::do_import(Import_function_body* ifb, Location loc)
{
ifb->require_c_string("goto ");
std::string id = ifb->read_identifier();
if (id[0] != '$')
{
Function* fn = ifb->function()->func_value();
Label* label = fn->add_label_reference(ifb->gogo(), id, loc, false);
return Statement::make_goto_statement(label, loc);
}
else
{
if (id[1] != 'l')
{
if (!ifb->saw_error())
go_error_at(loc,
("invalid export data for %qs: "
"bad unnamed label at %lu"),
ifb->name().c_str(),
static_cast<unsigned long>(ifb->off()));
ifb->set_saw_error();
return Statement::make_error_statement(loc);
}
const char* p = id.c_str();
char* end;
long idx = strtol(p + 2, &end, 10);
if (*end != '\0' || idx > 0x7fffffff)
{
if (!ifb->saw_error())
go_error_at(loc,
("invalid export data for %qs: "
"bad unnamed label index at %lu"),
ifb->name().c_str(),
static_cast<unsigned long>(ifb->off()));
ifb->set_saw_error();
return Statement::make_error_statement(loc);
}
Unnamed_label* label = ifb->unnamed_label(idx, loc);
return Statement::make_goto_unnamed_statement(label, loc);
}
}
// Dump the AST representation for a goto statement.
void
Goto_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->ostream() << "goto " << this->label_->name() << dsuffix(location()) << std::endl;
}
// Make a goto statement.
Statement*
Statement::make_goto_statement(Label* label, Location location)
{
return new Goto_statement(label, location);
}
// Class Goto_unnamed_statement.
int
Goto_unnamed_statement::do_traverse(Traverse*)
{
return TRAVERSE_CONTINUE;
}
// Convert the goto unnamed statement to the backend representation.
Bstatement*
Goto_unnamed_statement::do_get_backend(Translate_context* context)
{
return this->label_->get_goto(context, this->location());
}
// Export a goto unnamed statement.
void
Goto_unnamed_statement::do_export_statement(Export_function_body *efb)
{
unsigned int index = efb->unnamed_label_index(this->label_);
char buf[100];
snprintf(buf, sizeof buf, "goto $l%u", index);
efb->write_c_string(buf);
}
// Dump the AST representation for an unnamed goto statement
void
Goto_unnamed_statement::do_dump_statement(
Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->ostream() << "goto ";
ast_dump_context->dump_label_name(this->label_);
ast_dump_context->ostream() << dsuffix(location()) << std::endl;
}
// Make a goto statement to an unnamed label.
Statement*
Statement::make_goto_unnamed_statement(Unnamed_label* label,
Location location)
{
return new Goto_unnamed_statement(label, location);
}
// Class Label_statement.
// Traversal.
int
Label_statement::do_traverse(Traverse*)
{
return TRAVERSE_CONTINUE;
}
// Return the backend representation of the statement defining this
// label.
Bstatement*
Label_statement::do_get_backend(Translate_context* context)
{
if (this->label_->is_dummy_label())
{
Bexpression* bce = context->backend()->boolean_constant_expression(false);
Bfunction* bfunction = context->function()->func_value()->get_decl();
return context->backend()->expression_statement(bfunction, bce);
}
Blabel* blabel = this->label_->get_backend_label(context);
return context->backend()->label_definition_statement(blabel);
}
// Export a label.
void
Label_statement::do_export_statement(Export_function_body* efb)
{
if (this->label_->is_dummy_label())
return;
// We use a leading colon, not a trailing one, to simplify import.
efb->write_c_string(":");
efb->write_string(this->label_->name());
}
// Import a label or an unnamed label.
Statement*
Label_statement::do_import(Import_function_body* ifb, Location loc)
{
ifb->require_c_string(":");
std::string id = ifb->read_identifier();
if (id[0] != '$')
{
Function* fn = ifb->function()->func_value();
Label* label = fn->add_label_definition(ifb->gogo(), id, loc);
return Statement::make_label_statement(label, loc);
}
else
{
if (id[1] != 'l')
{
if (!ifb->saw_error())
go_error_at(loc,
("invalid export data for %qs: "
"bad unnamed label at %lu"),
ifb->name().c_str(),
static_cast<unsigned long>(ifb->off()));
ifb->set_saw_error();
return Statement::make_error_statement(loc);
}
const char* p = id.c_str();
char* end;
long idx = strtol(p + 2, &end, 10);
if (*end != '\0' || idx > 0x7fffffff)
{
if (!ifb->saw_error())
go_error_at(loc,
("invalid export data for %qs: "
"bad unnamed label index at %lu"),
ifb->name().c_str(),
static_cast<unsigned long>(ifb->off()));
ifb->set_saw_error();
return Statement::make_error_statement(loc);
}
Unnamed_label* label = ifb->unnamed_label(idx, loc);
return Statement::make_unnamed_label_statement(label);
}
}
// Dump the AST for a label definition statement.
void
Label_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->ostream() << this->label_->name() << ":" << dsuffix(location()) << std::endl;
}
// Make a label statement.
Statement*
Statement::make_label_statement(Label* label, Location location)
{
return new Label_statement(label, location);
}
// Class Unnamed_label_statement.
Unnamed_label_statement::Unnamed_label_statement(Unnamed_label* label)
: Statement(STATEMENT_UNNAMED_LABEL, label->location()),
label_(label)
{ }
int
Unnamed_label_statement::do_traverse(Traverse*)
{
return TRAVERSE_CONTINUE;
}
// Get the backend definition for this unnamed label statement.
Bstatement*
Unnamed_label_statement::do_get_backend(Translate_context* context)
{
return this->label_->get_definition(context);
}
// Export an unnamed label.
void
Unnamed_label_statement::do_export_statement(Export_function_body* efb)
{
unsigned int index = efb->unnamed_label_index(this->label_);
char buf[50];
// We use a leading colon, not a trailing one, to simplify import.
snprintf(buf, sizeof buf, ":$l%u", index);
efb->write_c_string(buf);
}
// Dump the AST representation for an unnamed label definition statement.
void
Unnamed_label_statement::do_dump_statement(Ast_dump_context* ast_dump_context)
const
{
ast_dump_context->print_indent();
ast_dump_context->dump_label_name(this->label_);
ast_dump_context->ostream() << ":" << dsuffix(location()) << std::endl;
}
// Make an unnamed label statement.
Statement*
Statement::make_unnamed_label_statement(Unnamed_label* label)
{
return new Unnamed_label_statement(label);
}
// Class If_statement.
// Traversal.
int
If_statement::do_traverse(Traverse* traverse)
{
if (this->traverse_expression(traverse, &this->cond_) == TRAVERSE_EXIT
|| this->then_block_->traverse(traverse) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
if (this->else_block_ != NULL)
{
if (this->else_block_->traverse(traverse) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
}
return TRAVERSE_CONTINUE;
}
void
If_statement::do_determine_types()
{
Type_context context(Type::lookup_bool_type(), false);
this->cond_->determine_type(&context);
this->then_block_->determine_types();
if (this->else_block_ != NULL)
this->else_block_->determine_types();
}
// Check types.
void
If_statement::do_check_types(Gogo*)
{
Type* type = this->cond_->type();
if (type->is_error())
this->set_is_error();
else if (!type->is_boolean_type())
this->report_error(_("expected boolean expression"));
}
// Whether the overall statement may fall through.
bool
If_statement::do_may_fall_through() const
{
return (this->else_block_ == NULL
|| this->then_block_->may_fall_through()
|| this->else_block_->may_fall_through());
}
// Get the backend representation.
Bstatement*
If_statement::do_get_backend(Translate_context* context)
{
go_assert(this->cond_->type()->is_boolean_type()
|| this->cond_->type()->is_error());
Bexpression* cond = this->cond_->get_backend(context);
Bblock* then_block = this->then_block_->get_backend(context);
Bblock* else_block = (this->else_block_ == NULL
? NULL
: this->else_block_->get_backend(context));
Bfunction* bfunction = context->function()->func_value()->get_decl();
return context->backend()->if_statement(bfunction,
cond, then_block, else_block,
this->location());
}
// Export an if statement.
void
If_statement::do_export_statement(Export_function_body* efb)
{
efb->write_c_string("if ");
this->cond_->export_expression(efb);
efb->write_c_string(" ");
Block_statement::export_block(efb, this->then_block_, false);
if (this->else_block_ != NULL)
{
efb->write_c_string(" else ");
Block_statement::export_block(efb, this->else_block_, false);
}
}
// Import an if statement.
Statement*
If_statement::do_import(Import_function_body* ifb, Location loc)
{
ifb->require_c_string("if ");
Expression* cond = Expression::import_expression(ifb, loc);
ifb->require_c_string(" ");
if (!ifb->match_c_string("{"))
{
if (!ifb->saw_error())
go_error_at(ifb->location(),
"import error for %qs: no block for if statement at %lu",
ifb->name().c_str(),
static_cast<unsigned long>(ifb->off()));
ifb->set_saw_error();
return Statement::make_error_statement(loc);
}
bool is_lowered_for_statement;
Block* then_block = Block_statement::do_import(ifb, loc,
&is_lowered_for_statement);
if (then_block == NULL)
return Statement::make_error_statement(loc);
if (is_lowered_for_statement)
{
if (!ifb->saw_error())
go_error_at(ifb->location(),
("import error for %qs: "
"unexpected lowered for in if statement at %lu"),
ifb->name().c_str(),
static_cast<unsigned long>(ifb->off()));
ifb->set_saw_error();
return Statement::make_error_statement(loc);
}
Block* else_block = NULL;
if (ifb->match_c_string(" else "))
{
ifb->advance(6);
if (!ifb->match_c_string("{"))
{
if (!ifb->saw_error())
go_error_at(ifb->location(),
("import error for %qs: no else block "
"for if statement at %lu"),
ifb->name().c_str(),
static_cast<unsigned long>(ifb->off()));
ifb->set_saw_error();
return Statement::make_error_statement(loc);
}
else_block = Block_statement::do_import(ifb, loc,
&is_lowered_for_statement);
if (else_block == NULL)
return Statement::make_error_statement(loc);
if (is_lowered_for_statement)
{
if (!ifb->saw_error())
go_error_at(ifb->location(),
("import error for %qs: "
"unexpected lowered for in if statement at %lu"),
ifb->name().c_str(),
static_cast<unsigned long>(ifb->off()));
ifb->set_saw_error();
return Statement::make_error_statement(loc);
}
}
return Statement::make_if_statement(cond, then_block, else_block, loc);
}
// Dump the AST representation for an if statement
void
If_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->ostream() << "if ";
ast_dump_context->dump_expression(this->cond_);
ast_dump_context->ostream() << dsuffix(location()) << std::endl;
if (ast_dump_context->dump_subblocks())
{
ast_dump_context->dump_block(this->then_block_);
if (this->else_block_ != NULL)
{
ast_dump_context->print_indent();
ast_dump_context->ostream() << "else" << std::endl;
ast_dump_context->dump_block(this->else_block_);
}
}
}
// Make an if statement.
Statement*
Statement::make_if_statement(Expression* cond, Block* then_block,
Block* else_block, Location location)
{
return new If_statement(cond, then_block, else_block, location);
}
// Class Case_clauses::Hash_integer_value.
class Case_clauses::Hash_integer_value
{
public:
size_t
operator()(Expression*) const;
};
size_t
Case_clauses::Hash_integer_value::operator()(Expression* pe) const
{
Numeric_constant nc;
mpz_t ival;
if (!pe->numeric_constant_value(&nc) || !nc.to_int(&ival))
go_unreachable();
size_t ret = mpz_get_ui(ival);
mpz_clear(ival);
return ret;
}
// Class Case_clauses::Eq_integer_value.
class Case_clauses::Eq_integer_value
{
public:
bool
operator()(Expression*, Expression*) const;
};
bool
Case_clauses::Eq_integer_value::operator()(Expression* a, Expression* b) const
{
Numeric_constant anc;
mpz_t aval;
Numeric_constant bnc;
mpz_t bval;
if (!a->numeric_constant_value(&anc)
|| !anc.to_int(&aval)
|| !b->numeric_constant_value(&bnc)
|| !bnc.to_int(&bval))
go_unreachable();
bool ret = mpz_cmp(aval, bval) == 0;
mpz_clear(aval);
mpz_clear(bval);
return ret;
}
// Class Case_clauses::Case_clause.
// Traversal.
int
Case_clauses::Case_clause::traverse(Traverse* traverse)
{
if (this->cases_ != NULL
&& (traverse->traverse_mask()
& (Traverse::traverse_types | Traverse::traverse_expressions)) != 0)
{
if (this->cases_->traverse(traverse) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
}
if (this->statements_ != NULL)
{
if (this->statements_->traverse(traverse) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
}
return TRAVERSE_CONTINUE;
}
// Check whether all the case expressions are integer constants.
bool
Case_clauses::Case_clause::is_constant() const
{
if (this->cases_ != NULL)
{
for (Expression_list::const_iterator p = this->cases_->begin();
p != this->cases_->end();
++p)
if (!(*p)->is_constant() || (*p)->type()->integer_type() == NULL)
return false;
}
return true;
}
// Lower a case clause for a nonconstant switch. VAL_TEMP is the
// value we are switching on; it may be NULL. If START_LABEL is not
// NULL, it goes at the start of the statements, after the condition
// test. We branch to FINISH_LABEL at the end of the statements.
void
Case_clauses::Case_clause::lower(Block* b, Temporary_statement* val_temp,
Unnamed_label* start_label,
Unnamed_label* finish_label) const
{
Location loc = this->location_;
Unnamed_label* next_case_label;
if (this->cases_ == NULL || this->cases_->empty())
{
go_assert(this->is_default_);
next_case_label = NULL;
}
else
{
Expression* cond = NULL;
for (Expression_list::const_iterator p = this->cases_->begin();
p != this->cases_->end();
++p)
{
Expression* ref = Expression::make_temporary_reference(val_temp,
loc);
Expression* this_cond = Expression::make_binary(OPERATOR_EQEQ, ref,
*p, loc);
if (cond == NULL)
cond = this_cond;
else
cond = Expression::make_binary(OPERATOR_OROR, cond, this_cond, loc);
}
Block* then_block = new Block(b, loc);
next_case_label = new Unnamed_label(Linemap::unknown_location());
Statement* s = Statement::make_goto_unnamed_statement(next_case_label,
loc);
then_block->add_statement(s);
// if !COND { goto NEXT_CASE_LABEL }
cond = Expression::make_unary(OPERATOR_NOT, cond, loc);
s = Statement::make_if_statement(cond, then_block, NULL, loc);
b->add_statement(s);
}
if (start_label != NULL)
b->add_statement(Statement::make_unnamed_label_statement(start_label));
if (this->statements_ != NULL)
b->add_statement(Statement::make_block_statement(this->statements_, loc));
Statement* s = Statement::make_goto_unnamed_statement(finish_label, loc);
b->add_statement(s);
if (next_case_label != NULL)
b->add_statement(Statement::make_unnamed_label_statement(next_case_label));
}
// Determine types.
void
Case_clauses::Case_clause::determine_types(Type* type)
{
if (this->cases_ != NULL)
{
Type_context case_context(type, false);
for (Expression_list::iterator p = this->cases_->begin();
p != this->cases_->end();
++p)
(*p)->determine_type(&case_context);
}
if (this->statements_ != NULL)
this->statements_->determine_types();
}
// Check types. Returns false if there was an error.
bool
Case_clauses::Case_clause::check_types(Type* type)
{
if (this->cases_ != NULL)
{
for (Expression_list::iterator p = this->cases_->begin();
p != this->cases_->end();
++p)
{
if (!Type::are_assignable(type, (*p)->type(), NULL)
&& !Type::are_assignable((*p)->type(), type, NULL))
{
go_error_at((*p)->location(),
"type mismatch between switch value and case clause");
return false;
}
}
}
return true;
}
// Return true if this clause may fall through to the following
// statements. Note that this is not the same as whether the case
// uses the "fallthrough" keyword.
bool
Case_clauses::Case_clause::may_fall_through() const
{
if (this->statements_ == NULL)
return true;
return this->statements_->may_fall_through();
}
// Convert the case values and statements to the backend
// representation. BREAK_LABEL is the label which break statements
// should branch to. CASE_CONSTANTS is used to detect duplicate
// constants. *CASES should be passed as an empty vector; the values
// for this case will be added to it. If this is the default case,
// *CASES will remain empty. This returns the statement to execute if
// one of these cases is selected.
Bstatement*
Case_clauses::Case_clause::get_backend(Translate_context* context,
Unnamed_label* break_label,
Case_constants* case_constants,
std::vector<Bexpression*>* cases) const
{
if (this->cases_ != NULL)
{
go_assert(!this->is_default_);
for (Expression_list::const_iterator p = this->cases_->begin();
p != this->cases_->end();
++p)
{
Expression* e = *p;
if (e->classification() != Expression::EXPRESSION_INTEGER)
{
Numeric_constant nc;
mpz_t ival;
if (!(*p)->numeric_constant_value(&nc) || !nc.to_int(&ival))
{
// Something went wrong. This can happen with a
// negative constant and an unsigned switch value.
go_assert(saw_errors());
continue;
}
go_assert(nc.type() != NULL);
e = Expression::make_integer_z(&ival, nc.type(), e->location());
mpz_clear(ival);
}
std::pair<Case_constants::iterator, bool> ins =
case_constants->insert(e);
if (!ins.second)
{
// Value was already present.
go_error_at(this->location_, "duplicate case in switch");
e = Expression::make_error(this->location_);
}
cases->push_back(e->get_backend(context));
}
}
Bstatement* statements;
if (this->statements_ == NULL)
statements = NULL;
else
{
Bblock* bblock = this->statements_->get_backend(context);
statements = context->backend()->block_statement(bblock);
}
Bstatement* break_stat;
if (this->is_fallthrough_)
break_stat = NULL;
else
break_stat = break_label->get_goto(context, this->location_);
if (statements == NULL)
return break_stat;
else if (break_stat == NULL)
return statements;
else
return context->backend()->compound_statement(statements, break_stat);
}
// Dump the AST representation for a case clause
void
Case_clauses::Case_clause::dump_clause(Ast_dump_context* ast_dump_context)
const
{
ast_dump_context->print_indent();
if (this->is_default_)
{
ast_dump_context->ostream() << "default:";
}
else
{
ast_dump_context->ostream() << "case ";
ast_dump_context->dump_expression_list(this->cases_);
ast_dump_context->ostream() << ":" ;
}
ast_dump_context->dump_block(this->statements_);
if (this->is_fallthrough_)
{
ast_dump_context->print_indent();
ast_dump_context->ostream() << " (fallthrough)" << dsuffix(location()) << std::endl;
}
}
// Class Case_clauses.
// Traversal.
int
Case_clauses::traverse(Traverse* traverse)
{
for (Clauses::iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p)
{
if (p->traverse(traverse) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
}
return TRAVERSE_CONTINUE;
}
// Check whether all the case expressions are constant.
bool
Case_clauses::is_constant() const
{
for (Clauses::const_iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p)
if (!p->is_constant())
return false;
return true;
}
// Lower case clauses for a nonconstant switch.
void
Case_clauses::lower(Block* b, Temporary_statement* val_temp,
Unnamed_label* break_label) const
{
// The default case.
const Case_clause* default_case = NULL;
// The label for the fallthrough of the previous case.
Unnamed_label* last_fallthrough_label = NULL;
// The label for the start of the default case. This is used if the
// case before the default case falls through.
Unnamed_label* default_start_label = NULL;
// The label for the end of the default case. This normally winds
// up as BREAK_LABEL, but it will be different if the default case
// falls through.
Unnamed_label* default_finish_label = NULL;
for (Clauses::const_iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p)
{
// The label to use for the start of the statements for this
// case. This is NULL unless the previous case falls through.
Unnamed_label* start_label = last_fallthrough_label;
// The label to jump to after the end of the statements for this
// case.
Unnamed_label* finish_label = break_label;
last_fallthrough_label = NULL;
if (p->is_fallthrough() && p + 1 != this->clauses_.end())
{
finish_label = new Unnamed_label(p->location());
last_fallthrough_label = finish_label;
}
if (!p->is_default())
p->lower(b, val_temp, start_label, finish_label);
else
{
// We have to move the default case to the end, so that we
// only use it if all the other tests fail.
default_case = &*p;
default_start_label = start_label;
default_finish_label = finish_label;
}
}
if (default_case != NULL)
default_case->lower(b, val_temp, default_start_label,
default_finish_label);
}
// Determine types.
void
Case_clauses::determine_types(Type* type)
{
for (Clauses::iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p)
p->determine_types(type);
}
// Check types. Returns false if there was an error.
bool
Case_clauses::check_types(Type* type)
{
bool ret = true;
for (Clauses::iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p)
{
if (!p->check_types(type))
ret = false;
}
return ret;
}
// Return true if these clauses may fall through to the statements
// following the switch statement.
bool
Case_clauses::may_fall_through() const
{
bool found_default = false;
for (Clauses::const_iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p)
{
if (p->may_fall_through() && !p->is_fallthrough())
return true;
if (p->is_default())
found_default = true;
}
return !found_default;
}
// Convert the cases to the backend representation. This sets
// *ALL_CASES and *ALL_STATEMENTS.
void
Case_clauses::get_backend(Translate_context* context,
Unnamed_label* break_label,
std::vector<std::vector<Bexpression*> >* all_cases,
std::vector<Bstatement*>* all_statements) const
{
Case_constants case_constants;
size_t c = this->clauses_.size();
all_cases->resize(c);
all_statements->resize(c);
size_t i = 0;
for (Clauses::const_iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p, ++i)
{
std::vector<Bexpression*> cases;
Bstatement* stat = p->get_backend(context, break_label, &case_constants,
&cases);
// The final clause can't fall through.
if (i == c - 1 && p->is_fallthrough())
{
go_assert(saw_errors());
stat = context->backend()->error_statement();
}
(*all_cases)[i].swap(cases);
(*all_statements)[i] = stat;
}
}
// Dump the AST representation for case clauses (from a switch statement)
void
Case_clauses::dump_clauses(Ast_dump_context* ast_dump_context) const
{
for (Clauses::const_iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p)
p->dump_clause(ast_dump_context);
}
// A constant switch statement. A Switch_statement is lowered to this
// when all the cases are constants.
class Constant_switch_statement : public Statement
{
public:
Constant_switch_statement(Expression* val, Case_clauses* clauses,
Unnamed_label* break_label,
Location location)
: Statement(STATEMENT_CONSTANT_SWITCH, location),
val_(val), clauses_(clauses), break_label_(break_label)
{ }
protected:
int
do_traverse(Traverse*);
void
do_determine_types();
void
do_check_types(Gogo*);
Bstatement*
do_get_backend(Translate_context*);
void
do_dump_statement(Ast_dump_context*) const;
private:
// The value to switch on.
Expression* val_;
// The case clauses.
Case_clauses* clauses_;
// The break label, if needed.
Unnamed_label* break_label_;
};
// Traversal.
int
Constant_switch_statement::do_traverse(Traverse* traverse)
{
if (this->traverse_expression(traverse, &this->val_) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
return this->clauses_->traverse(traverse);
}
// Determine types.
void
Constant_switch_statement::do_determine_types()
{
this->val_->determine_type_no_context();
this->clauses_->determine_types(this->val_->type());
}
// Check types.
void
Constant_switch_statement::do_check_types(Gogo*)
{
if (!this->clauses_->check_types(this->val_->type()))
this->set_is_error();
}
// Convert to GENERIC.
Bstatement*
Constant_switch_statement::do_get_backend(Translate_context* context)
{
Bexpression* switch_val_expr = this->val_->get_backend(context);
Unnamed_label* break_label = this->break_label_;
if (break_label == NULL)
break_label = new Unnamed_label(this->location());
std::vector<std::vector<Bexpression*> > all_cases;
std::vector<Bstatement*> all_statements;
this->clauses_->get_backend(context, break_label, &all_cases,
&all_statements);
Bfunction* bfunction = context->function()->func_value()->get_decl();
Bstatement* switch_statement;
switch_statement = context->backend()->switch_statement(bfunction,
switch_val_expr,
all_cases,
all_statements,
this->location());
Bstatement* ldef = break_label->get_definition(context);
return context->backend()->compound_statement(switch_statement, ldef);
}
// Dump the AST representation for a constant switch statement.
void
Constant_switch_statement::do_dump_statement(Ast_dump_context* ast_dump_context)
const
{
ast_dump_context->print_indent();
ast_dump_context->ostream() << "switch ";
ast_dump_context->dump_expression(this->val_);
if (ast_dump_context->dump_subblocks())
{
ast_dump_context->ostream() << " {" << std::endl;
this->clauses_->dump_clauses(ast_dump_context);
ast_dump_context->ostream() << "}";
}
ast_dump_context->ostream() << std::endl;
}
// Class Switch_statement.
// Traversal.
int
Switch_statement::do_traverse(Traverse* traverse)
{
if (this->val_ != NULL)
{
if (this->traverse_expression(traverse, &this->val_) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
}
return this->clauses_->traverse(traverse);
}
// Lower a Switch_statement to a Constant_switch_statement or a series
// of if statements.
Statement*
Switch_statement::do_lower(Gogo*, Named_object*, Block* enclosing,
Statement_inserter*)
{
Location loc = this->location();
if (this->val_ != NULL
&& (this->val_->is_error_expression()
|| this->val_->type()->is_error()))
{
go_assert(saw_errors());
return Statement::make_error_statement(loc);
}
if (this->val_ != NULL
&& this->val_->type()->integer_type() != NULL
&& !this->clauses_->empty()
&& this->clauses_->is_constant())
return new Constant_switch_statement(this->val_, this->clauses_,
this->break_label_, loc);
if (this->val_ != NULL
&& !this->val_->type()->is_comparable()
&& !Type::are_compatible_for_comparison(true, this->val_->type(),
Type::make_nil_type(), NULL))
{
go_error_at(this->val_->location(),
"cannot switch on value whose type may not be compared");
return Statement::make_error_statement(loc);
}
Block* b = new Block(enclosing, loc);
if (this->clauses_->empty())
{
Expression* val = this->val_;
if (val == NULL)
val = Expression::make_boolean(true, loc);
return Statement::make_statement(val, true);
}
// var val_temp VAL_TYPE = VAL
Expression* val = this->val_;
if (val == NULL)
val = Expression::make_boolean(true, loc);
Type* type = val->type();
if (type->is_abstract())
type = type->make_non_abstract_type();
Temporary_statement* val_temp = Statement::make_temporary(type, val, loc);
b->add_statement(val_temp);
this->clauses_->lower(b, val_temp, this->break_label());
Statement* s = Statement::make_unnamed_label_statement(this->break_label_);
b->add_statement(s);
return Statement::make_block_statement(b, loc);
}
// Return the break label for this switch statement, creating it if
// necessary.
Unnamed_label*
Switch_statement::break_label()
{
if (this->break_label_ == NULL)
this->break_label_ = new Unnamed_label(this->location());
return this->break_label_;
}
// Dump the AST representation for a switch statement.
void
Switch_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->ostream() << "switch ";
if (this->val_ != NULL)
{
ast_dump_context->dump_expression(this->val_);
}
if (ast_dump_context->dump_subblocks())
{
ast_dump_context->ostream() << " {" << dsuffix(location()) << std::endl;
this->clauses_->dump_clauses(ast_dump_context);
ast_dump_context->print_indent();
ast_dump_context->ostream() << "}";
}
ast_dump_context->ostream() << std::endl;
}
// Return whether this switch may fall through.
bool
Switch_statement::do_may_fall_through() const
{
if (this->clauses_ == NULL)
return true;
// If we have a break label, then some case needed it. That implies
// that the switch statement as a whole can fall through.
if (this->break_label_ != NULL)
return true;
return this->clauses_->may_fall_through();
}
// Make a switch statement.
Switch_statement*
Statement::make_switch_statement(Expression* val, Location location)
{
return new Switch_statement(val, location);
}
// Class Type_case_clauses::Type_case_clause.
// Traversal.
int
Type_case_clauses::Type_case_clause::traverse(Traverse* traverse)
{
if (!this->is_default_
&& ((traverse->traverse_mask()
& (Traverse::traverse_types | Traverse::traverse_expressions)) != 0)
&& Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
if (this->statements_ != NULL)
return this->statements_->traverse(traverse);
return TRAVERSE_CONTINUE;
}
// Lower one clause in a type switch. Add statements to the block B.
// The type descriptor we are switching on is in DESCRIPTOR_TEMP.
// BREAK_LABEL is the label at the end of the type switch.
// *STMTS_LABEL, if not NULL, is a label to put at the start of the
// statements.
void
Type_case_clauses::Type_case_clause::lower(Gogo* gogo,
Type* switch_val_type,
Block* b,
Temporary_statement* descriptor_temp,
Unnamed_label* break_label,
Unnamed_label** stmts_label) const
{
Location loc = this->location_;
Unnamed_label* next_case_label = NULL;
if (!this->is_default_)
{
Type* type = this->type_;
std::string reason;
if (switch_val_type->interface_type() != NULL
&& !type->is_nil_constant_as_type()
&& type->interface_type() == NULL
&& !switch_val_type->interface_type()->implements_interface(type,
&reason))
{
if (reason.empty())
go_error_at(this->location_, "impossible type switch case");
else
go_error_at(this->location_, "impossible type switch case (%s)",
reason.c_str());
}
Expression* ref = Expression::make_temporary_reference(descriptor_temp,
loc);
Expression* cond;
// The language permits case nil, which is of course a constant
// rather than a type. It will appear here as an invalid
// forwarding type.
if (type->is_nil_constant_as_type())
cond = Expression::make_binary(OPERATOR_EQEQ, ref,
Expression::make_nil(loc),
loc);
else if (type->interface_type() == NULL)
{
if (!gogo->need_eqtype())
cond = Expression::make_binary(OPERATOR_EQEQ, ref,
Expression::make_type_descriptor(type, loc),
loc);
else
cond = Runtime::make_call(Runtime::EQTYPE, loc, 2,
Expression::make_type_descriptor(type, loc),
ref);
}
else
cond = Runtime::make_call(Runtime::IFACET2IP, loc, 2,
Expression::make_type_descriptor(type, loc),
ref);
Unnamed_label* dest;
if (!this->is_fallthrough_)
{
// if !COND { goto NEXT_CASE_LABEL }
next_case_label = new Unnamed_label(Linemap::unknown_location());
dest = next_case_label;
cond = Expression::make_unary(OPERATOR_NOT, cond, loc);
}
else
{
// if COND { goto STMTS_LABEL }
go_assert(stmts_label != NULL);
if (*stmts_label == NULL)
*stmts_label = new Unnamed_label(Linemap::unknown_location());
dest = *stmts_label;
}
Block* then_block = new Block(b, loc);
Statement* s = Statement::make_goto_unnamed_statement(dest, loc);
then_block->add_statement(s);
s = Statement::make_if_statement(cond, then_block, NULL, loc);
b->add_statement(s);
}
if (this->statements_ != NULL
|| (!this->is_fallthrough_
&& stmts_label != NULL
&& *stmts_label != NULL))
{
go_assert(!this->is_fallthrough_);
if (stmts_label != NULL && *stmts_label != NULL)
{
go_assert(!this->is_default_);
if (this->statements_ != NULL)
(*stmts_label)->set_location(this->statements_->start_location());
Statement* s = Statement::make_unnamed_label_statement(*stmts_label);
b->add_statement(s);
*stmts_label = NULL;
}
if (this->statements_ != NULL)
b->add_statement(Statement::make_block_statement(this->statements_,
loc));
}
if (this->is_fallthrough_)
go_assert(next_case_label == NULL);
else
{
Location gloc = (this->statements_ == NULL
? loc
: this->statements_->end_location());
b->add_statement(Statement::make_goto_unnamed_statement(break_label,
gloc));
if (next_case_label != NULL)
{
Statement* s =
Statement::make_unnamed_label_statement(next_case_label);
b->add_statement(s);
}
}
}
// Return true if this type clause may fall through to the statements
// following the switch.
bool
Type_case_clauses::Type_case_clause::may_fall_through() const
{
if (this->is_fallthrough_)
{
// This case means that we automatically fall through to the
// next case (it's used for T1 in case T1, T2:). It does not
// mean that we fall through to the end of the type switch as a
// whole. There is sure to be a next case and that next case
// will determine whether we fall through to the statements
// after the type switch.
return false;
}
if (this->statements_ == NULL)
return true;
return this->statements_->may_fall_through();
}
// Dump the AST representation for a type case clause
void
Type_case_clauses::Type_case_clause::dump_clause(
Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
if (this->is_default_)
{
ast_dump_context->ostream() << "default:";
}
else
{
ast_dump_context->ostream() << "case ";
ast_dump_context->dump_type(this->type_);
ast_dump_context->ostream() << ":" ;
}
ast_dump_context->dump_block(this->statements_);
if (this->is_fallthrough_)
{
ast_dump_context->print_indent();
ast_dump_context->ostream() << " (fallthrough)" << std::endl;
}
}
// Class Type_case_clauses.
// Traversal.
int
Type_case_clauses::traverse(Traverse* traverse)
{
for (Type_clauses::iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p)
{
if (p->traverse(traverse) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
}
return TRAVERSE_CONTINUE;
}
// Check for duplicate types.
void
Type_case_clauses::check_duplicates() const
{
typedef Unordered_set_hash(const Type*, Type_hash_identical,
Type_identical) Types_seen;
Types_seen types_seen;
for (Type_clauses::const_iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p)
{
Type* t = p->type();
if (t == NULL)
continue;
if (t->is_nil_constant_as_type())
t = Type::make_nil_type();
std::pair<Types_seen::iterator, bool> ins = types_seen.insert(t);
if (!ins.second)
go_error_at(p->location(), "duplicate type in switch");
}
}
// Lower the clauses in a type switch. Add statements to the block B.
// The type descriptor we are switching on is in DESCRIPTOR_TEMP.
// BREAK_LABEL is the label at the end of the type switch.
void
Type_case_clauses::lower(Gogo* gogo, Type* switch_val_type,
Block* b,
Temporary_statement* descriptor_temp,
Unnamed_label* break_label) const
{
const Type_case_clause* default_case = NULL;
Unnamed_label* stmts_label = NULL;
for (Type_clauses::const_iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p)
{
if (!p->is_default())
p->lower(gogo, switch_val_type, b, descriptor_temp, break_label,
&stmts_label);
else
{
// We are generating a series of tests, which means that we
// need to move the default case to the end.
default_case = &*p;
}
}
go_assert(stmts_label == NULL);
if (default_case != NULL)
default_case->lower(gogo, switch_val_type, b, descriptor_temp, break_label,
NULL);
}
// Return true if these clauses may fall through to the statements
// following the switch statement.
bool
Type_case_clauses::may_fall_through() const
{
bool found_default = false;
for (Type_clauses::const_iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p)
{
if (p->may_fall_through())
return true;
if (p->is_default())
found_default = true;
}
return !found_default;
}
// Dump the AST representation for case clauses (from a switch statement)
void
Type_case_clauses::dump_clauses(Ast_dump_context* ast_dump_context) const
{
for (Type_clauses::const_iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p)
p->dump_clause(ast_dump_context);
}
// Class Type_switch_statement.
// Traversal.
int
Type_switch_statement::do_traverse(Traverse* traverse)
{
if (this->traverse_expression(traverse, &this->expr_) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
if (this->clauses_ != NULL)
return this->clauses_->traverse(traverse);
return TRAVERSE_CONTINUE;
}
// Lower a type switch statement to a series of if statements. The gc
// compiler is able to generate a table in some cases. However, that
// does not work for us because we may have type descriptors in
// different shared libraries, so we can't compare them with simple
// equality testing.
Statement*
Type_switch_statement::do_lower(Gogo* gogo, Named_object*, Block* enclosing,
Statement_inserter*)
{
const Location loc = this->location();
if (this->clauses_ != NULL)
this->clauses_->check_duplicates();
Block* b = new Block(enclosing, loc);
Type* val_type = this->expr_->type();
if (val_type->interface_type() == NULL)
{
if (!val_type->is_error())
this->report_error(_("cannot type switch on non-interface value"));
return Statement::make_error_statement(loc);
}
Temporary_statement* val_temp =
Statement::make_temporary(NULL, this->expr_, loc);
b->add_statement(val_temp);
// var descriptor_temp DESCRIPTOR_TYPE
Type* descriptor_type = Type::make_type_descriptor_ptr_type();
Temporary_statement* descriptor_temp =
Statement::make_temporary(descriptor_type, NULL, loc);
b->add_statement(descriptor_temp);
// descriptor_temp = ifacetype(val_temp)
Expression* ref = Expression::make_temporary_reference(val_temp, loc);
Expression* td = Expression::get_interface_type_descriptor(ref);
Temporary_reference_expression* lhs =
Expression::make_temporary_reference(descriptor_temp, loc);
lhs->set_is_lvalue();
Statement* s = Statement::make_assignment(lhs, td, loc);
b->add_statement(s);
if (this->clauses_ != NULL)
this->clauses_->lower(gogo, val_type, b, descriptor_temp, this->break_label());
s = Statement::make_unnamed_label_statement(this->break_label_);
b->add_statement(s);
return Statement::make_block_statement(b, loc);
}
// Return whether this switch may fall through.
bool
Type_switch_statement::do_may_fall_through() const
{
if (this->clauses_ == NULL)
return true;
// If we have a break label, then some case needed it. That implies
// that the switch statement as a whole can fall through.
if (this->break_label_ != NULL)
return true;
return this->clauses_->may_fall_through();
}
// Return the break label for this type switch statement, creating it
// if necessary.
Unnamed_label*
Type_switch_statement::break_label()
{
if (this->break_label_ == NULL)
this->break_label_ = new Unnamed_label(this->location());
return this->break_label_;
}
// Dump the AST representation for a type switch statement
void
Type_switch_statement::do_dump_statement(Ast_dump_context* ast_dump_context)
const
{
ast_dump_context->print_indent();
ast_dump_context->ostream() << "switch ";
if (!this->name_.empty())
ast_dump_context->ostream() << this->name_ << " = ";
ast_dump_context->dump_expression(this->expr_);
ast_dump_context->ostream() << " .(type)";
if (ast_dump_context->dump_subblocks())
{
ast_dump_context->ostream() << " {" << dsuffix(location()) << std::endl;
this->clauses_->dump_clauses(ast_dump_context);
ast_dump_context->ostream() << "}";
}
ast_dump_context->ostream() << std::endl;
}
// Make a type switch statement.
Type_switch_statement*
Statement::make_type_switch_statement(const std::string& name, Expression* expr,
Location location)
{
return new Type_switch_statement(name, expr, location);
}
// Class Send_statement.
// Traversal.
int
Send_statement::do_traverse(Traverse* traverse)
{
if (this->traverse_expression(traverse, &this->channel_) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
return this->traverse_expression(traverse, &this->val_);
}
// Determine types.
void
Send_statement::do_determine_types()
{
this->channel_->determine_type_no_context();
Type* type = this->channel_->type();
Type_context context;
if (type->channel_type() != NULL)
context.type = type->channel_type()->element_type();
this->val_->determine_type(&context);
}
// Check types.
void
Send_statement::do_check_types(Gogo*)
{
Type* type = this->channel_->type();
if (type->is_error())
{
this->set_is_error();
return;
}
Channel_type* channel_type = type->channel_type();
if (channel_type == NULL)
{
go_error_at(this->location(), "left operand of %<<-%> must be channel");
this->set_is_error();
return;
}
Type* element_type = channel_type->element_type();
if (!Type::are_assignable(element_type, this->val_->type(), NULL))
{
this->report_error(_("incompatible types in send"));
return;
}
if (!channel_type->may_send())
{
this->report_error(_("invalid send on receive-only channel"));
return;
}
}
// Flatten a send statement. We may need a temporary for interface
// conversion.
Statement*
Send_statement::do_flatten(Gogo*, Named_object*, Block*,
Statement_inserter* inserter)
{
if (this->channel_->is_error_expression()
|| this->channel_->type()->is_error_type())
{
go_assert(saw_errors());
return Statement::make_error_statement(this->location());
}
Type* element_type = this->channel_->type()->channel_type()->element_type();
if (!Type::are_identical(element_type, this->val_->type(),
Type::COMPARE_ERRORS | Type::COMPARE_TAGS,
NULL)
&& this->val_->type()->interface_type() != NULL
&& !this->val_->is_variable())
{
Temporary_statement* temp =
Statement::make_temporary(NULL, this->val_, this->location());
inserter->insert(temp);
this->val_ = Expression::make_temporary_reference(temp,
this->location());
}
return this;
}
// Add explicit type conversions.
void
Send_statement::do_add_conversions()
{
Type* lt = this->channel_->type()->channel_type()->element_type();
Type* rt = this->val_->type();
if (!Type::are_identical(lt, rt, 0, NULL)
&& lt->interface_type() != NULL)
this->val_ = Expression::make_cast(lt, this->val_, this->location());
}
// Convert a send statement to the backend representation.
Bstatement*
Send_statement::do_get_backend(Translate_context* context)
{
Location loc = this->location();
Channel_type* channel_type = this->channel_->type()->channel_type();
Type* element_type = channel_type->element_type();
Expression* val = Expression::convert_for_assignment(context->gogo(),
element_type,
this->val_, loc);
bool can_take_address;
switch (element_type->base()->classification())
{
case Type::TYPE_BOOLEAN:
case Type::TYPE_INTEGER:
case Type::TYPE_FUNCTION:
case Type::TYPE_POINTER:
case Type::TYPE_MAP:
case Type::TYPE_CHANNEL:
case Type::TYPE_FLOAT:
case Type::TYPE_COMPLEX:
case Type::TYPE_STRING:
case Type::TYPE_INTERFACE:
can_take_address = false;
break;
case Type::TYPE_STRUCT:
can_take_address = true;
break;
case Type::TYPE_ARRAY:
can_take_address = !element_type->is_slice_type();
break;
default:
case Type::TYPE_ERROR:
case Type::TYPE_VOID:
case Type::TYPE_SINK:
case Type::TYPE_NIL:
case Type::TYPE_NAMED:
case Type::TYPE_FORWARD:
go_assert(saw_errors());
return context->backend()->error_statement();
}
// Only try to take the address of a variable. We have already
// moved variables to the heap, so this should not cause that to
// happen unnecessarily.
if (can_take_address
&& val->var_expression() == NULL
&& val->temporary_reference_expression() == NULL)
can_take_address = false;
Bstatement* btemp = NULL;
if (can_take_address)
{
// The function doesn't change the value, so just take its
// address directly.
val = Expression::make_unary(OPERATOR_AND, val, loc);
}
else
{
// The value is not in a variable, or is small enough that it
// might be in a register, and taking the address would push it
// on the stack. Copy it into a temporary variable to take the
// address.
Temporary_statement* temp = Statement::make_temporary(element_type,
val, loc);
Expression* ref = Expression::make_temporary_reference(temp, loc);
val = Expression::make_unary(OPERATOR_AND, ref, loc);
btemp = temp->get_backend(context);
}
Expression* call = Runtime::make_call(Runtime::CHANSEND, loc, 2,
this->channel_, val);
context->gogo()->lower_expression(context->function(), NULL, &call);
Bexpression* bcall = call->get_backend(context);
Bfunction* bfunction = context->function()->func_value()->get_decl();
Bstatement* s = context->backend()->expression_statement(bfunction, bcall);
if (btemp == NULL)
return s;
else
return context->backend()->compound_statement(btemp, s);
}
// Dump the AST representation for a send statement
void
Send_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->dump_expression(this->channel_);
ast_dump_context->ostream() << " <- ";
ast_dump_context->dump_expression(this->val_);
ast_dump_context->ostream() << dsuffix(location()) << std::endl;
}
// Make a send statement.
Send_statement*
Statement::make_send_statement(Expression* channel, Expression* val,
Location location)
{
return new Send_statement(channel, val, location);
}
// Class Select_clauses::Select_clause.
// Traversal.
int
Select_clauses::Select_clause::traverse(Traverse* traverse)
{
if (!this->is_lowered_
&& (traverse->traverse_mask()
& (Traverse::traverse_types | Traverse::traverse_expressions)) != 0)
{
if (this->channel_ != NULL)
{
if (Expression::traverse(&this->channel_, traverse) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
}
if (this->val_ != NULL)
{
if (Expression::traverse(&this->val_, traverse) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
}
if (this->closed_ != NULL)
{
if (Expression::traverse(&this->closed_, traverse) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
}
}
if (this->statements_ != NULL)
{
if (this->statements_->traverse(traverse) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
}
return TRAVERSE_CONTINUE;
}
// Lowering. We call a function to register this clause, and arrange
// to set any variables in any receive clause.
void
Select_clauses::Select_clause::lower(Gogo* gogo, Named_object* function,
Block* b, Temporary_statement* scases,
int index, Temporary_statement* recvok)
{
Location loc = this->location_;
this->set_case_index(index);
if (this->is_default_)
{
go_assert(this->channel_ == NULL && this->val_ == NULL);
this->is_lowered_ = true;
return;
}
Expression* scase = Expression::make_temporary_reference(scases, loc);
Expression* index_expr = Expression::make_integer_sl(index, NULL, loc);
scase = Expression::make_array_index(scase, index_expr, NULL, NULL, loc);
// Evaluate the channel before the select statement.
Temporary_statement* channel_temp = Statement::make_temporary(NULL,
this->channel_,
loc);
b->add_statement(channel_temp);
Expression* chanref = Expression::make_temporary_reference(channel_temp,
loc);
if (this->is_send_)
this->lower_send(b, scase, chanref);
else
this->lower_recv(gogo, function, b, scase, chanref, recvok);
// Now all references should be handled through the statements, not
// through here.
this->is_lowered_ = true;
this->val_ = NULL;
}
// Lower a send clause in a select statement.
void
Select_clauses::Select_clause::lower_send(Block* b, Expression* scase,
Expression* chanref)
{
Location loc = this->location_;
Channel_type* ct = this->channel_->type()->channel_type();
if (ct == NULL)
return;
Type* valtype = ct->element_type();
// Note that copying the value to a temporary here means that we
// evaluate the send values in the required order.
Temporary_statement* val = Statement::make_temporary(valtype, this->val_,
loc);
// The value here escapes, because it might be sent on a channel.
// We record that via the Temporary_statement, so that the escape
// analysis pass can pick it up. The gc compiler lowers select
// statements after escape analysis, so it doesn't have to worry
// about this.
val->set_value_escapes();
b->add_statement(val);
Expression* valref = Expression::make_temporary_reference(val, loc);
Expression* valaddr = Expression::make_unary(OPERATOR_AND, valref, loc);
Type* unsafe_pointer_type = Type::make_pointer_type(Type::make_void_type());
valaddr = Expression::make_cast(unsafe_pointer_type, valaddr, loc);
this->set_case(b, scase, chanref, valaddr);
}
// Lower a receive clause in a select statement.
void
Select_clauses::Select_clause::lower_recv(Gogo* gogo, Named_object* function,
Block* b, Expression* scase,
Expression* chanref,
Temporary_statement* recvok)
{
Location loc = this->location_;
Channel_type* ct = this->channel_->type()->channel_type();
if (ct == NULL)
return;
Type* valtype = ct->element_type();
Temporary_statement* val = Statement::make_temporary(valtype, NULL, loc);
b->add_statement(val);
Expression* valref = Expression::make_temporary_reference(val, loc);
Expression* valaddr = Expression::make_unary(OPERATOR_AND, valref, loc);
Type* unsafe_pointer_type = Type::make_pointer_type(Type::make_void_type());
valaddr = Expression::make_cast(unsafe_pointer_type, valaddr, loc);
this->set_case(b, scase, chanref, valaddr);
// If the block of statements is executed, arrange for the received
// value to move from VAL to the place where the statements expect
// it.
Block* init = NULL;
if (this->var_ != NULL)
{
go_assert(this->val_ == NULL);
valref = Expression::make_temporary_reference(val, loc);
this->var_->var_value()->set_init(valref);
this->var_->var_value()->clear_type_from_chan_element();
}
else if (this->val_ != NULL && !this->val_->is_sink_expression())
{
init = new Block(b, loc);
valref = Expression::make_temporary_reference(val, loc);
init->add_statement(Statement::make_assignment(this->val_, valref, loc));
}
if (this->closedvar_ != NULL)
{
go_assert(this->closed_ == NULL);
Expression* cref = Expression::make_temporary_reference(recvok, loc);
this->closedvar_->var_value()->set_init(cref);
}
else if (this->closed_ != NULL && !this->closed_->is_sink_expression())
{
if (init == NULL)
init = new Block(b, loc);
Expression* cref = Expression::make_temporary_reference(recvok, loc);
init->add_statement(Statement::make_assignment(this->closed_, cref,
loc));
}
if (init != NULL)
{
gogo->lower_block(function, init);
if (this->statements_ != NULL)
init->add_statement(Statement::make_block_statement(this->statements_,
loc));
this->statements_ = init;
}
}
// Set the fields of an scase struct, an element in the array that we
// pass to the runtime function selectgo.
void
Select_clauses::Select_clause::set_case(Block* b,
Expression* scase,
Expression* chanref,
Expression* elem)
{
Location loc = this->location_;
Struct_type* scase_type = scase->type()->struct_type();
int field_index = 0;
go_assert(scase_type->field(field_index)->is_field_name("c"));
Expression* ref = Expression::make_field_reference(scase, field_index, loc);
Type* unsafe_pointer_type = Type::make_pointer_type(Type::make_void_type());
chanref = Expression::make_unsafe_cast(unsafe_pointer_type, chanref, loc);
Statement* s = Statement::make_assignment(ref, chanref, loc);
b->add_statement(s);
if (elem != NULL)
{
field_index = 1;
go_assert(scase_type->field(field_index)->is_field_name("elem"));
ref = Expression::make_field_reference(scase->copy(), field_index, loc);
s = Statement::make_assignment(ref, elem, loc);
b->add_statement(s);
}
}
// Determine types.
void
Select_clauses::Select_clause::determine_types()
{
go_assert(this->is_lowered_);
if (this->statements_ != NULL)
this->statements_->determine_types();
}
// Check types.
void
Select_clauses::Select_clause::check_types()
{
if (this->is_default_)
return;
Channel_type* ct = this->channel_->type()->channel_type();
if (ct == NULL)
{
go_error_at(this->channel_->location(), "expected channel");
return;
}
if (this->is_send_ && !ct->may_send())
go_error_at(this->location(), "invalid send on receive-only channel");
else if (!this->is_send_ && !ct->may_receive())
go_error_at(this->location(), "invalid receive on send-only channel");
}
// Whether this clause may fall through to the statement which follows
// the overall select statement.
bool
Select_clauses::Select_clause::may_fall_through() const
{
if (this->statements_ == NULL)
return true;
return this->statements_->may_fall_through();
}
// Return the backend representation for the statements to execute.
Bstatement*
Select_clauses::Select_clause::get_statements_backend(
Translate_context* context)
{
if (this->statements_ == NULL)
return NULL;
Bblock* bblock = this->statements_->get_backend(context);
return context->backend()->block_statement(bblock);
}
// Dump the AST representation for a select case clause
void
Select_clauses::Select_clause::dump_clause(
Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
if (this->is_default_)
{
ast_dump_context->ostream() << "default:";
}
else
{
ast_dump_context->ostream() << "case " ;
if (this->is_send_)
{
ast_dump_context->dump_expression(this->channel_);
ast_dump_context->ostream() << " <- " ;
if (this->val_ != NULL)
ast_dump_context->dump_expression(this->val_);
}
else
{
if (this->val_ != NULL)
ast_dump_context->dump_expression(this->val_);
if (this->closed_ != NULL)
{
// FIXME: can val_ == NULL and closed_ ! = NULL?
ast_dump_context->ostream() << " , " ;
ast_dump_context->dump_expression(this->closed_);
}
if (this->closedvar_ != NULL || this->var_ != NULL)
ast_dump_context->ostream() << " := " ;
ast_dump_context->ostream() << " <- " ;
ast_dump_context->dump_expression(this->channel_);
}
ast_dump_context->ostream() << ":" ;
}
ast_dump_context->dump_block(this->statements_);
}
// Class Select_clauses.
// Whether there is a default case.
bool
Select_clauses::has_default() const
{
for (Clauses::const_iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p)
if (p->is_default())
return true;
return false;
}
// Traversal.
int
Select_clauses::traverse(Traverse* traverse)
{
for (Clauses::iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p)
{
if (p->traverse(traverse) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
}
return TRAVERSE_CONTINUE;
}
// Lowering. Here we pull out the channel and the send values, to
// enforce the order of evaluation. We also add explicit send and
// receive statements to the clauses. This builds the entries in the
// local array of scase values. It sets *P_SEND_COUNT and
// *P_RECV_COUNT.
void
Select_clauses::lower(Gogo* gogo, Named_object* function, Block* b,
Temporary_statement* scases, Temporary_statement* recvok,
int *p_send_count, int *p_recv_count)
{
int send_count = 0;
int recv_count = 0;
bool has_default = false;
for (Clauses::iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p)
{
if (p->is_default())
has_default = true;
else if (p->is_send())
++send_count;
else
++recv_count;
}
*p_send_count = send_count;
*p_recv_count = recv_count;
int send_index = 0;
int recv_index = send_count;
for (Clauses::iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p)
{
int index;
if (p->is_default())
index = -1;
else if (p->is_send())
{
index = send_index;
++send_index;
}
else
{
index = recv_index;
++recv_index;
}
p->lower(gogo, function, b, scases, index, recvok);
}
go_assert(send_index == send_count);
go_assert(recv_index == send_count + recv_count);
go_assert(static_cast<size_t>(recv_index + (has_default ? 1 : 0))
== this->size());
}
// Determine types.
void
Select_clauses::determine_types()
{
for (Clauses::iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p)
p->determine_types();
}
// Check types.
void
Select_clauses::check_types()
{
for (Clauses::iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p)
p->check_types();
}
// Return whether these select clauses fall through to the statement
// following the overall select statement.
bool
Select_clauses::may_fall_through() const
{
for (Clauses::const_iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p)
if (p->may_fall_through())
return true;
return false;
}
// Convert to the backend representation. Assemble the clauses and
// build a switch statement on the index value returned by the call to
// selectgo.
Bstatement*
Select_clauses::get_backend(Translate_context* context,
Temporary_statement* index,
Unnamed_label *break_label,
Location location)
{
size_t count = this->clauses_.size();
std::vector<std::vector<Bexpression*> > cases(count + 1);
std::vector<Bstatement*> clauses(count + 1);
Type* int_type = Type::lookup_integer_type("int");
int i = 0;
for (Clauses::iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p, ++i)
{
Expression* index_expr = Expression::make_integer_sl(p->case_index(),
int_type,
location);
cases[i].push_back(index_expr->get_backend(context));
Bstatement* s = p->get_statements_backend(context);
Location gloc = (p->statements() == NULL
? p->location()
: p->statements()->end_location());
Bstatement* g = break_label->get_goto(context, gloc);
if (s == NULL)
clauses[i] = g;
else
clauses[i] = context->backend()->compound_statement(s, g);
}
Expression* ref = Expression::make_temporary_reference(index, location);
Bexpression* bindex = ref->get_backend(context);
Bfunction* bfunction = context->function()->func_value()->get_decl();
if (count == 0)
return context->backend()->expression_statement(bfunction, bindex);
Expression* crash = Runtime::make_call(Runtime::UNREACHABLE, location, 0);
Bexpression* bcrash = crash->get_backend(context);
clauses[count] = context->backend()->expression_statement(bfunction, bcrash);
std::vector<Bstatement*> statements;
statements.reserve(2);
Bstatement* switch_stmt = context->backend()->switch_statement(bfunction,
bindex,
cases,
clauses,
location);
statements.push_back(switch_stmt);
Bstatement* ldef = break_label->get_definition(context);
statements.push_back(ldef);
return context->backend()->statement_list(statements);
}
// Dump the AST representation for select clauses.
void
Select_clauses::dump_clauses(Ast_dump_context* ast_dump_context) const
{
for (Clauses::const_iterator p = this->clauses_.begin();
p != this->clauses_.end();
++p)
p->dump_clause(ast_dump_context);
}
// Class Select_statement.
// Return the break label for this switch statement, creating it if
// necessary.
Unnamed_label*
Select_statement::break_label()
{
if (this->break_label_ == NULL)
this->break_label_ = new Unnamed_label(this->location());
return this->break_label_;
}
// Lower a select statement. This will return a block containing this
// select statement. The block will implement the order of evaluation
// rules, include the send and receive statements as explicit
// statements in the clauses, and call the runtime selectgo function.
Statement*
Select_statement::do_lower(Gogo* gogo, Named_object* function,
Block* enclosing, Statement_inserter*)
{
if (this->is_lowered_)
return this;
Location loc = this->location();
Block* b = new Block(enclosing, loc);
int ncases = this->clauses_->size();
bool has_default = this->clauses_->has_default();
// Zero-case select. Just block the execution.
if (ncases == 0)
{
Expression* call = Runtime::make_call(Runtime::BLOCK, loc, 0);
Statement *s = Statement::make_statement(call, false);
b->add_statement(s);
this->is_lowered_ = true;
return Statement::make_block_statement(b, loc);
}
// One-case select. It is mostly just to run the case.
if (ncases == 1)
return this->lower_one_case(b);
// Two-case select with one default case. It is a non-blocking
// send/receive.
if (ncases == 2 && has_default)
return this->lower_two_case(b);
// We don't allocate an entry in scases for the default case.
if (has_default)
--ncases;
Type* scase_type = Channel_type::select_case_type();
Expression* ncases_expr =
Expression::make_integer_ul(ncases, NULL,
Linemap::predeclared_location());
Array_type* scases_type = Type::make_array_type(scase_type, ncases_expr);
scases_type->set_is_array_incomparable();
Temporary_statement* scases = Statement::make_temporary(scases_type, NULL,
loc);
b->add_statement(scases);
Expression* ncases2_expr =
Expression::make_integer_ul(ncases * 2, NULL,
Linemap::predeclared_location());
Type* uint16_type = Type::lookup_integer_type("uint16");
Array_type* order_type = Type::make_array_type(uint16_type, ncases2_expr);
order_type->set_is_array_incomparable();
Temporary_statement* order = Statement::make_temporary(order_type, NULL,
loc);
b->add_statement(order);
Type* int_type = Type::lookup_integer_type("int");
this->index_ = Statement::make_temporary(int_type, NULL, loc);
b->add_statement(this->index_);
Type* bool_type = Type::lookup_bool_type();
Temporary_statement* recvok = Statement::make_temporary(bool_type, NULL,
loc);
b->add_statement(recvok);
// Initialize the scases array.
int send_count;
int recv_count;
this->clauses_->lower(gogo, function, b, scases, recvok, &send_count,
&recv_count);
// Build the call to selectgo. Later, in do_get_backend, we will
// build a switch on the result that branches to the various cases.
Expression* scases_ref = Expression::make_temporary_reference(scases, loc);
scases_ref = Expression::make_unary(OPERATOR_AND, scases_ref, loc);
Type* unsafe_pointer_type = Type::make_pointer_type(Type::make_void_type());
scases_ref = Expression::make_cast(unsafe_pointer_type, scases_ref, loc);
Expression* order_ref = Expression::make_temporary_reference(order, loc);
order_ref = Expression::make_unary(OPERATOR_AND, order_ref, loc);
order_ref = Expression::make_cast(unsafe_pointer_type, order_ref, loc);
Expression* send_count_expr = Expression::make_integer_sl(send_count,
int_type,
loc);
Expression* recv_count_expr = Expression::make_integer_sl(recv_count,
int_type,
loc);
Expression* block_expr = Expression::make_boolean(!has_default, loc);
Call_expression* call = Runtime::make_call(Runtime::SELECTGO, loc, 5,
scases_ref, order_ref,
send_count_expr, recv_count_expr,
block_expr);
Expression* result = Expression::make_call_result(call, 0);
Expression* ref = Expression::make_temporary_reference(this->index_, loc);
Statement* s = Statement::make_assignment(ref, result, loc);
b->add_statement(s);
result = Expression::make_call_result(call, 1);
ref = Expression::make_temporary_reference(recvok, loc);
s = Statement::make_assignment(ref, result, loc);
b->add_statement(s);
this->is_lowered_ = true;
b->add_statement(this);
return Statement::make_block_statement(b, loc);
}
// Lower a one-case select statement.
Statement*
Select_statement::lower_one_case(Block* b)
{
Select_clauses::Select_clause& scase = this->clauses_->at(0);
Location loc = this->location();
Expression* chan = scase.channel();
if (chan != NULL)
{
// Lower this to
// if chan == nil { block() }; send/recv; body
Temporary_statement* chantmp = Statement::make_temporary(NULL, chan, loc);
b->add_statement(chantmp);
Expression* chanref = Expression::make_temporary_reference(chantmp, loc);
Expression* nil = Expression::make_nil(loc);
Expression* cond = Expression::make_binary(OPERATOR_EQEQ, chanref, nil, loc);
Block* bnil = new Block(b, loc);
Expression* call = Runtime::make_call(Runtime::BLOCK, loc, 0);
Statement* s = Statement::make_statement(call, false);
bnil->add_statement(s);
Statement* ifs = Statement::make_if_statement(cond, bnil, NULL, loc);
b->add_statement(ifs);
chanref = chanref->copy();
Location cloc = scase.location();
if (scase.is_send())
{
s = Statement::make_send_statement(chanref, scase.val(), cloc);
b->add_statement(s);
}
else
{
if (scase.closed() == NULL && scase.closedvar() == NULL)
{
// Simple receive.
Expression* recv = Expression::make_receive(chanref, cloc);
if (scase.val() != NULL)
s = Statement::make_assignment(scase.val(), recv, cloc);
else if (scase.var() != NULL)
{
Temporary_statement *ts =
Statement::make_temporary(NULL, recv, cloc);
Expression* ref =
Expression::make_temporary_reference(ts, cloc);
s = ts;
scase.var()->var_value()->set_init(ref);
scase.var()->var_value()->clear_type_from_chan_element();
}
else
s = Statement::make_statement(recv, false);
b->add_statement(s);
}
else
{
// Tuple receive.
Expression* lhs;
if (scase.val() != NULL)
lhs = scase.val();
else
{
Type* valtype = chan->type()->channel_type()->element_type();
Temporary_statement *ts =
Statement::make_temporary(valtype, NULL, cloc);
lhs = Expression::make_temporary_reference(ts, cloc);
b->add_statement(ts);
}
Expression* lhs2;
if (scase.closed() != NULL)
lhs2 = scase.closed();
else
{
Type* booltype = Type::make_boolean_type();
Temporary_statement *ts =
Statement::make_temporary(booltype, NULL, cloc);
lhs2 = Expression::make_temporary_reference(ts, cloc);
b->add_statement(ts);
}
s = Statement::make_tuple_receive_assignment(lhs, lhs2, chanref, cloc);
b->add_statement(s);
if (scase.var() != NULL)
{
scase.var()->var_value()->set_init(lhs->copy());
scase.var()->var_value()->clear_type_from_chan_element();
}
if (scase.closedvar() != NULL)
scase.closedvar()->var_value()->set_init(lhs2->copy());
}
}
}
Statement* bs =
Statement::make_block_statement(scase.statements(), scase.location());
b->add_statement(bs);
Statement* label =
Statement::make_unnamed_label_statement(this->break_label());
b->add_statement(label);
this->is_lowered_ = true;
return Statement::make_block_statement(b, loc);
}
// Lower a two-case select statement with one default case.
Statement*
Select_statement::lower_two_case(Block* b)
{
Select_clauses::Select_clause& chancase =
(this->clauses_->at(0).is_default()
? this->clauses_->at(1)
: this->clauses_->at(0));
Select_clauses::Select_clause& defcase =
(this->clauses_->at(0).is_default()
? this->clauses_->at(0)
: this->clauses_->at(1));
Location loc = this->location();
Expression* chan = chancase.channel();
Type* valtype = chan->type()->channel_type()->element_type();
Temporary_statement* chantmp = Statement::make_temporary(NULL, chan, loc);
b->add_statement(chantmp);
Expression* chanref = Expression::make_temporary_reference(chantmp, loc);
Block* bchan;
Expression* call;
if (chancase.is_send())
{
// if selectnbsend(chan, &val) { body } else { default body }
Temporary_statement* ts =
Statement::make_temporary(valtype, chancase.val(), loc);
// Tell the escape analysis that the value escapes, as it may be sent
// to a channel.
ts->set_value_escapes();
b->add_statement(ts);
Expression* ref = Expression::make_temporary_reference(ts, loc);
Expression* addr = Expression::make_unary(OPERATOR_AND, ref, loc);
call = Runtime::make_call(Runtime::SELECTNBSEND, loc, 2, chanref, addr);
bchan = chancase.statements();
}
else
{
Temporary_statement* ts = Statement::make_temporary(valtype, NULL, loc);
b->add_statement(ts);
Expression* ref = Expression::make_temporary_reference(ts, loc);
Expression* addr = Expression::make_unary(OPERATOR_AND, ref, loc);
Expression* okref = NULL;
if (chancase.closed() == NULL && chancase.closedvar() == NULL)
{
// Simple receive.
// if selectnbrecv(&lhs, chan) { body } else { default body }
call = Runtime::make_call(Runtime::SELECTNBRECV, loc, 2, addr, chanref);
}
else
{
// Tuple receive.
// if selectnbrecv2(&lhs, &ok, chan) { body } else { default body }
Type* booltype = Type::make_boolean_type();
Temporary_statement* okts = Statement::make_temporary(booltype, NULL,
loc);
b->add_statement(okts);
okref = Expression::make_temporary_reference(okts, loc);
Expression* okaddr = Expression::make_unary(OPERATOR_AND, okref, loc);
call = Runtime::make_call(Runtime::SELECTNBRECV2, loc, 3, addr, okaddr,
chanref);
}
Location cloc = chancase.location();
bchan = new Block(b, loc);
if (chancase.val() != NULL && !chancase.val()->is_sink_expression())
{
Statement* as = Statement::make_assignment(chancase.val(), ref->copy(),
cloc);
bchan->add_statement(as);
}
else if (chancase.var() != NULL)
{
chancase.var()->var_value()->set_init(ref->copy());
chancase.var()->var_value()->clear_type_from_chan_element();
}
if (chancase.closed() != NULL && !chancase.closed()->is_sink_expression())
{
Statement* as = Statement::make_assignment(chancase.closed(),
okref->copy(), cloc);
bchan->add_statement(as);
}
else if (chancase.closedvar() != NULL)
chancase.closedvar()->var_value()->set_init(okref->copy());
Statement* bs = Statement::make_block_statement(chancase.statements(),
cloc);
bchan->add_statement(bs);
}
Statement* ifs =
Statement::make_if_statement(call, bchan, defcase.statements(), loc);
b->add_statement(ifs);
Statement* label =
Statement::make_unnamed_label_statement(this->break_label());
b->add_statement(label);
this->is_lowered_ = true;
return Statement::make_block_statement(b, loc);
}
// Whether the select statement itself may fall through to the following
// statement.
bool
Select_statement::do_may_fall_through() const
{
// A select statement is terminating if no break statement
// refers to it and all of its clauses are terminating.
if (this->break_label_ != NULL)
return true;
return this->clauses_->may_fall_through();
}
// Return the backend representation for a select statement.
Bstatement*
Select_statement::do_get_backend(Translate_context* context)
{
return this->clauses_->get_backend(context, this->index_,
this->break_label(), this->location());
}
// Dump the AST representation for a select statement.
void
Select_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->ostream() << "select";
if (ast_dump_context->dump_subblocks())
{
ast_dump_context->ostream() << " {" << dsuffix(location()) << std::endl;
this->clauses_->dump_clauses(ast_dump_context);
ast_dump_context->print_indent();
ast_dump_context->ostream() << "}";
}
ast_dump_context->ostream() << std::endl;
}
// Make a select statement.
Select_statement*
Statement::make_select_statement(Location location)
{
return new Select_statement(location);
}
// Class For_statement.
// Traversal.
int
For_statement::do_traverse(Traverse* traverse)
{
if (this->init_ != NULL)
{
if (this->init_->traverse(traverse) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
}
if (this->cond_ != NULL)
{
if (this->traverse_expression(traverse, &this->cond_) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
}
if (this->post_ != NULL)
{
if (this->post_->traverse(traverse) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
}
return this->statements_->traverse(traverse);
}
// Lower a For_statement into if statements and gotos. Getting rid of
// complex statements make it easier to handle garbage collection.
Statement*
For_statement::do_lower(Gogo*, Named_object*, Block* enclosing,
Statement_inserter*)
{
Statement* s;
Location loc = this->location();
Block* b = new Block(enclosing, this->location());
if (this->init_ != NULL)
{
s = Statement::make_block_statement(this->init_,
this->init_->start_location());
b->add_statement(s);
}
Unnamed_label* entry = NULL;
if (this->cond_ != NULL)
{
entry = new Unnamed_label(this->location());
b->add_statement(Statement::make_goto_unnamed_statement(entry, loc));
}
Unnamed_label* top = new Unnamed_label(this->location());
top->set_derived_from(this);
b->add_statement(Statement::make_unnamed_label_statement(top));
s = Statement::make_block_statement(this->statements_,
this->statements_->start_location());
b->add_statement(s);
Location end_loc = this->statements_->end_location();
Unnamed_label* cont = this->continue_label_;
if (cont != NULL)
b->add_statement(Statement::make_unnamed_label_statement(cont));
if (this->post_ != NULL)
{
s = Statement::make_block_statement(this->post_,
this->post_->start_location());
b->add_statement(s);
end_loc = this->post_->end_location();
}
if (this->cond_ == NULL)
b->add_statement(Statement::make_goto_unnamed_statement(top, end_loc));
else
{
b->add_statement(Statement::make_unnamed_label_statement(entry));
Location cond_loc = this->cond_->location();
Block* then_block = new Block(b, cond_loc);
s = Statement::make_goto_unnamed_statement(top, cond_loc);
then_block->add_statement(s);
s = Statement::make_if_statement(this->cond_, then_block, NULL, cond_loc);
b->add_statement(s);
}
Unnamed_label* brk = this->break_label_;
if (brk != NULL)
b->add_statement(Statement::make_unnamed_label_statement(brk));
b->set_end_location(end_loc);
Statement* bs = Statement::make_block_statement(b, loc);
bs->block_statement()->set_is_lowered_for_statement();
return bs;
}
// Return the break label, creating it if necessary.
Unnamed_label*
For_statement::break_label()
{
if (this->break_label_ == NULL)
this->break_label_ = new Unnamed_label(this->location());
return this->break_label_;
}
// Return the continue LABEL_EXPR.
Unnamed_label*
For_statement::continue_label()
{
if (this->continue_label_ == NULL)
this->continue_label_ = new Unnamed_label(this->location());
return this->continue_label_;
}
// Set the break and continue labels a for statement. This is used
// when lowering a for range statement.
void
For_statement::set_break_continue_labels(Unnamed_label* break_label,
Unnamed_label* continue_label)
{
go_assert(this->break_label_ == NULL && this->continue_label_ == NULL);
this->break_label_ = break_label;
this->continue_label_ = continue_label;
}
// Whether the overall statement may fall through.
bool
For_statement::do_may_fall_through() const
{
// A for loop is terminating if it has no condition and
// no break statement.
if(this->cond_ != NULL)
return true;
if(this->break_label_ != NULL)
return true;
return false;
}
// Dump the AST representation for a for statement.
void
For_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
{
if (this->init_ != NULL && ast_dump_context->dump_subblocks())
{
ast_dump_context->print_indent();
ast_dump_context->indent();
ast_dump_context->ostream() << "// INIT " << std::endl;
ast_dump_context->dump_block(this->init_);
ast_dump_context->unindent();
}
ast_dump_context->print_indent();
ast_dump_context->ostream() << "for ";
if (this->cond_ != NULL)
ast_dump_context->dump_expression(this->cond_);
if (ast_dump_context->dump_subblocks())
{
ast_dump_context->ostream() << " {" << std::endl;
ast_dump_context->dump_block(this->statements_);
if (this->init_ != NULL)
{
ast_dump_context->print_indent();
ast_dump_context->ostream() << "// POST " << std::endl;
ast_dump_context->dump_block(this->post_);
}
ast_dump_context->unindent();
ast_dump_context->print_indent();
ast_dump_context->ostream() << "}";
}
ast_dump_context->ostream() << dsuffix(location()) << std::endl;
}
// Make a for statement.
For_statement*
Statement::make_for_statement(Block* init, Expression* cond, Block* post,
Location location)
{
return new For_statement(init, cond, post, location);
}
// Class For_range_statement.
// Traversal.
int
For_range_statement::do_traverse(Traverse* traverse)
{
if (this->index_var_ != NULL)
{
if (this->traverse_expression(traverse, &this->index_var_)
== TRAVERSE_EXIT)
return TRAVERSE_EXIT;
}
if (this->value_var_ != NULL)
{
if (this->traverse_expression(traverse, &this->value_var_)
== TRAVERSE_EXIT)
return TRAVERSE_EXIT;
}
if (this->traverse_expression(traverse, &this->range_) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
return this->statements_->traverse(traverse);
}
// Lower a for range statement. For simplicity we lower this into a
// for statement, which will then be lowered in turn to goto
// statements.
Statement*
For_range_statement::do_lower(Gogo* gogo, Named_object*, Block* enclosing,
Statement_inserter*)
{
Type* range_type = this->range_->type();
if (range_type->points_to() != NULL
&& range_type->points_to()->array_type() != NULL
&& !range_type->points_to()->is_slice_type())
range_type = range_type->points_to();
Type* index_type;
Type* value_type = NULL;
if (range_type->array_type() != NULL)
{
index_type = Type::lookup_integer_type("int");
value_type = range_type->array_type()->element_type();
}
else if (range_type->is_string_type())
{
index_type = Type::lookup_integer_type("int");
value_type = Type::lookup_integer_type("rune");
}
else if (range_type->map_type() != NULL)
{
index_type = range_type->map_type()->key_type();
value_type = range_type->map_type()->val_type();
}
else if (range_type->channel_type() != NULL)
{
index_type = range_type->channel_type()->element_type();
if (this->value_var_ != NULL)
{
if (!this->value_var_->type()->is_error())
this->report_error(_("too many variables for range clause "
"with channel"));
return Statement::make_error_statement(this->location());
}
}
else
{
this->report_error(_("range clause must have "
"array, slice, string, map, or channel type"));
return Statement::make_error_statement(this->location());
}
// If there is only one iteration variable, and len(this->range_) is
// constant, then we do not evaluate the range variable. len(x) is
// a contant if x is a string constant or if x is an array. If x is
// a constant then evaluating it won't make any difference, so the
// only case to consider is when x is an array whose length is constant.
bool eval = true;
if ((this->value_var_ == NULL || this->value_var_->is_sink_expression())
&& range_type->array_type() != NULL
&& !range_type->is_slice_type()
&& Builtin_call_expression::array_len_is_constant(this->range_))
eval = false;
Location loc = this->location();
Block* temp_block = new Block(enclosing, loc);
Expression* orig_range_expr = this->range_;
Named_object* range_object = NULL;
Temporary_statement* range_temp = NULL;
if (eval)
{
Var_expression* ve = this->range_->var_expression();
if (ve != NULL)
range_object = ve->named_object();
else
{
range_temp = Statement::make_temporary(NULL, this->range_, loc);
temp_block->add_statement(range_temp);
this->range_ = NULL;
}
}
// Try to match "range clear" patterns and rewrite to simple runtime
// calls.
if (range_type->map_type() != NULL)
{
Statement* clear = this->lower_map_range_clear(range_type,
enclosing,
orig_range_expr,
range_object,
range_temp, loc);
if (clear != NULL)
{
if (gogo->debug_optimization())
go_debug(loc, "map range clear");
temp_block->add_statement(clear);
return Statement::make_block_statement(temp_block, loc);
}
}
else if (range_type->array_type() != NULL)
{
// Slice or array.
Statement* clear = this->lower_array_range_clear(gogo,
range_type,
orig_range_expr,
temp_block,
range_object,
range_temp, loc);
if (clear != NULL)
{
if (gogo->debug_optimization())
go_debug(loc, "array range clear");
temp_block->add_statement(clear);
return Statement::make_block_statement(temp_block, loc);
}
}
Temporary_statement* index_temp = Statement::make_temporary(index_type,
NULL, loc);
temp_block->add_statement(index_temp);
Temporary_statement* value_temp = NULL;
if (this->value_var_ != NULL && !this->value_var_->is_sink_expression())
{
value_temp = Statement::make_temporary(value_type, NULL, loc);
temp_block->add_statement(value_temp);
}
Block* body = new Block(temp_block, loc);
Block* init;
Expression* cond;
Block* iter_init;
Block* post;
// Arrange to do a loop appropriate for the type. We will produce
// for INIT ; COND ; POST {
// ITER_INIT
// INDEX = INDEX_TEMP
// VALUE = VALUE_TEMP // If there is a value
// original statements
// }
if (range_type->is_slice_type())
this->lower_range_slice(gogo, temp_block, body, range_object, range_temp,
index_temp, value_temp, &init, &cond, &iter_init,
&post);
else if (range_type->array_type() != NULL)
this->lower_range_array(gogo, temp_block, body, range_object, range_temp,
index_temp, value_temp, &init, &cond, &iter_init,
&post);
else if (range_type->is_string_type())
this->lower_range_string(gogo, temp_block, body, range_object, range_temp,
index_temp, value_temp, &init, &cond, &iter_init,
&post);
else if (range_type->map_type() != NULL)
this->lower_range_map(gogo, range_type->map_type(), temp_block, body,
range_object, range_temp, index_temp, value_temp,
&init, &cond, &iter_init, &post);
else if (range_type->channel_type() != NULL)
this->lower_range_channel(gogo, temp_block, body, range_object, range_temp,
index_temp, value_temp, &init, &cond, &iter_init,
&post);
else
go_unreachable();
if (iter_init != NULL)
body->add_statement(Statement::make_block_statement(iter_init, loc));
if (this->index_var_ != NULL)
{
Statement* assign;
Expression* index_ref =
Expression::make_temporary_reference(index_temp, loc);
if (this->value_var_ == NULL || this->value_var_->is_sink_expression())
assign = Statement::make_assignment(this->index_var_, index_ref, loc);
else
{
Expression_list* lhs = new Expression_list();
lhs->push_back(this->index_var_);
lhs->push_back(this->value_var_);
Expression_list* rhs = new Expression_list();
rhs->push_back(index_ref);
rhs->push_back(Expression::make_temporary_reference(value_temp, loc));
assign = Statement::make_tuple_assignment(lhs, rhs, loc);
}
body->add_statement(assign);
}
body->add_statement(Statement::make_block_statement(this->statements_, loc));
body->set_end_location(this->statements_->end_location());
For_statement* loop = Statement::make_for_statement(init, cond, post,
this->location());
loop->add_statements(body);
loop->set_break_continue_labels(this->break_label_, this->continue_label_);
temp_block->add_statement(loop);
return Statement::make_block_statement(temp_block, loc);
}
// Return a reference to the range, which may be in RANGE_OBJECT or in
// RANGE_TEMP.
Expression*
For_range_statement::make_range_ref(Named_object* range_object,
Temporary_statement* range_temp,
Location loc)
{
if (range_object != NULL)
return Expression::make_var_reference(range_object, loc);
else
return Expression::make_temporary_reference(range_temp, loc);
}
// Return a call to the predeclared function FUNCNAME passing a
// reference to the temporary variable ARG.
Call_expression*
For_range_statement::call_builtin(Gogo* gogo, const char* funcname,
Expression* arg,
Location loc)
{
Named_object* no = gogo->lookup_global(funcname);
go_assert(no != NULL && no->is_function_declaration());
Expression* func = Expression::make_func_reference(no, NULL, loc);
Expression_list* params = new Expression_list();
params->push_back(arg);
return Expression::make_call(func, params, false, loc);
}
// Lower a for range over an array.
void
For_range_statement::lower_range_array(Gogo* gogo,
Block* enclosing,
Block* body_block,
Named_object* range_object,
Temporary_statement* range_temp,
Temporary_statement* index_temp,
Temporary_statement* value_temp,
Block** pinit,
Expression** pcond,
Block** piter_init,
Block** ppost)
{
Location loc = this->location();
// The loop we generate:
// len_temp := len(range)
// range_temp := range
// for index_temp = 0; index_temp < len_temp; index_temp++ {
// value_temp = range_temp[index_temp]
// index = index_temp
// value = value_temp
// original body
// }
// Set *PINIT to
// var len_temp int
// len_temp = len(range)
// index_temp = 0
Block* init = new Block(enclosing, loc);
Expression* len_arg;
if (range_object == NULL && range_temp == NULL)
{
// Don't evaluate this->range_, just get its length.
len_arg = this->range_;
}
else
{
Expression* ref = this->make_range_ref(range_object, range_temp, loc);
range_temp = Statement::make_temporary(NULL, ref, loc);
init->add_statement(range_temp);
len_arg = ref;
}
Expression* len_call = this->call_builtin(gogo, "len", len_arg, loc);
Temporary_statement* len_temp = Statement::make_temporary(index_temp->type(),
len_call, loc);
init->add_statement(len_temp);
Expression* zexpr = Expression::make_integer_ul(0, NULL, loc);
Temporary_reference_expression* tref =
Expression::make_temporary_reference(index_temp, loc);
tref->set_is_lvalue();
Statement* s = Statement::make_assignment(tref, zexpr, loc);
init->add_statement(s);
*pinit = init;
// Set *PCOND to
// index_temp < len_temp
Expression* ref = Expression::make_temporary_reference(index_temp, loc);
Expression* ref2 = Expression::make_temporary_reference(len_temp, loc);
Expression* lt = Expression::make_binary(OPERATOR_LT, ref, ref2, loc);
*pcond = lt;
// Set *PITER_INIT to
// value_temp = range[index_temp]
Block* iter_init = NULL;
if (value_temp != NULL)
{
iter_init = new Block(body_block, loc);
ref = Expression::make_temporary_reference(range_temp, loc);
ref2 = Expression::make_temporary_reference(index_temp, loc);
Expression* index = Expression::make_index(ref, ref2, NULL, NULL, loc);
tref = Expression::make_temporary_reference(value_temp, loc);
tref->set_is_lvalue();
s = Statement::make_assignment(tref, index, loc);
iter_init->add_statement(s);
}
*piter_init = iter_init;
// Set *PPOST to
// index_temp++
Block* post = new Block(enclosing, loc);
tref = Expression::make_temporary_reference(index_temp, loc);
tref->set_is_lvalue();
s = Statement::make_inc_statement(tref);
post->add_statement(s);
*ppost = post;
}
// Lower a for range over a slice.
void
For_range_statement::lower_range_slice(Gogo* gogo,
Block* enclosing,
Block* body_block,
Named_object* range_object,
Temporary_statement* range_temp,
Temporary_statement* index_temp,
Temporary_statement* value_temp,
Block** pinit,
Expression** pcond,
Block** piter_init,
Block** ppost)
{
Location loc = this->location();
// The loop we generate:
// for_temp := range
// len_temp := len(for_temp)
// for index_temp = 0; index_temp < len_temp; index_temp++ {
// value_temp = for_temp[index_temp]
// index = index_temp
// value = value_temp
// original body
// }
//
// Using for_temp means that we don't need to check bounds when
// fetching range_temp[index_temp].
// Set *PINIT to
// range_temp := range
// var len_temp int
// len_temp = len(range_temp)
// index_temp = 0
Block* init = new Block(enclosing, loc);
Expression* ref = this->make_range_ref(range_object, range_temp, loc);
Temporary_statement* for_temp = Statement::make_temporary(NULL, ref, loc);
init->add_statement(for_temp);
ref = Expression::make_temporary_reference(for_temp, loc);
Expression* len_call = this->call_builtin(gogo, "len", ref, loc);
Temporary_statement* len_temp = Statement::make_temporary(index_temp->type(),
len_call, loc);
init->add_statement(len_temp);
Expression* zexpr = Expression::make_integer_ul(0, NULL, loc);
Temporary_reference_expression* tref =
Expression::make_temporary_reference(index_temp, loc);
tref->set_is_lvalue();
Statement* s = Statement::make_assignment(tref, zexpr, loc);
init->add_statement(s);
*pinit = init;
// Set *PCOND to
// index_temp < len_temp
ref = Expression::make_temporary_reference(index_temp, loc);
Expression* ref2 = Expression::make_temporary_reference(len_temp, loc);
Expression* lt = Expression::make_binary(OPERATOR_LT, ref, ref2, loc);
*pcond = lt;
// Set *PITER_INIT to
// value_temp = range[index_temp]
Block* iter_init = NULL;
if (value_temp != NULL)
{
iter_init = new Block(body_block, loc);
ref = Expression::make_temporary_reference(for_temp, loc);
ref2 = Expression::make_temporary_reference(index_temp, loc);
Expression* index = Expression::make_index(ref, ref2, NULL, NULL, loc);
tref = Expression::make_temporary_reference(value_temp, loc);
tref->set_is_lvalue();
s = Statement::make_assignment(tref, index, loc);
iter_init->add_statement(s);
}
*piter_init = iter_init;
// Set *PPOST to
// index_temp++
Block* post = new Block(enclosing, loc);
tref = Expression::make_temporary_reference(index_temp, loc);
tref->set_is_lvalue();
s = Statement::make_inc_statement(tref);
post->add_statement(s);
*ppost = post;
}
// Lower a for range over a string.
void
For_range_statement::lower_range_string(Gogo* gogo,
Block* enclosing,
Block* body_block,
Named_object* range_object,
Temporary_statement* range_temp,
Temporary_statement* index_temp,
Temporary_statement* value_temp,
Block** pinit,
Expression** pcond,
Block** piter_init,
Block** ppost)
{
Location loc = this->location();
// The loop we generate:
// len_temp := len(range)
// var next_index_temp int
// for index_temp = 0; index_temp < len_temp; index_temp = next_index_temp {
// value_temp = rune(range[index_temp])
// if value_temp < utf8.RuneSelf {
// next_index_temp = index_temp + 1
// } else {
// value_temp, next_index_temp = decoderune(range, index_temp)
// }
// index = index_temp
// value = value_temp
// // original body
// }
// Set *PINIT to
// len_temp := len(range)
// var next_index_temp int
// index_temp = 0
// var value_temp rune // if value_temp not passed in
Block* init = new Block(enclosing, loc);
Expression* ref = this->make_range_ref(range_object, range_temp, loc);
Call_expression* call = this->call_builtin(gogo, "len", ref, loc);
Temporary_statement* len_temp =
Statement::make_temporary(index_temp->type(), call, loc);
init->add_statement(len_temp);
Temporary_statement* next_index_temp =
Statement::make_temporary(index_temp->type(), NULL, loc);
init->add_statement(next_index_temp);
Temporary_reference_expression* index_ref =
Expression::make_temporary_reference(index_temp, loc);
index_ref->set_is_lvalue();
Expression* zexpr = Expression::make_integer_ul(0, index_temp->type(), loc);
Statement* s = Statement::make_assignment(index_ref, zexpr, loc);
init->add_statement(s);
Type* rune_type;
if (value_temp != NULL)
rune_type = value_temp->type();
else
{
rune_type = Type::lookup_integer_type("rune");
value_temp = Statement::make_temporary(rune_type, NULL, loc);
init->add_statement(value_temp);
}
*pinit = init;
// Set *PCOND to
// index_temp < len_temp
index_ref = Expression::make_temporary_reference(index_temp, loc);
Expression* len_ref =
Expression::make_temporary_reference(len_temp, loc);
*pcond = Expression::make_binary(OPERATOR_LT, index_ref, len_ref, loc);
// Set *PITER_INIT to
// value_temp = rune(range[index_temp])
// if value_temp < utf8.RuneSelf {
// next_index_temp = index_temp + 1
// } else {
// value_temp, next_index_temp = decoderune(range, index_temp)
// }
Block* iter_init = new Block(body_block, loc);
ref = this->make_range_ref(range_object, range_temp, loc);
index_ref = Expression::make_temporary_reference(index_temp, loc);
ref = Expression::make_string_index(ref, index_ref, NULL, loc);
ref = Expression::make_cast(rune_type, ref, loc);
Temporary_reference_expression* value_ref =
Expression::make_temporary_reference(value_temp, loc);
value_ref->set_is_lvalue();
s = Statement::make_assignment(value_ref, ref, loc);
iter_init->add_statement(s);
value_ref = Expression::make_temporary_reference(value_temp, loc);
Expression* rune_self = Expression::make_integer_ul(0x80, rune_type, loc);
Expression* cond = Expression::make_binary(OPERATOR_LT, value_ref, rune_self,
loc);
Block* then_block = new Block(iter_init, loc);
Temporary_reference_expression* lhs =
Expression::make_temporary_reference(next_index_temp, loc);
lhs->set_is_lvalue();
index_ref = Expression::make_temporary_reference(index_temp, loc);
Expression* one = Expression::make_integer_ul(1, index_temp->type(), loc);
Expression* sum = Expression::make_binary(OPERATOR_PLUS, index_ref, one,
loc);
s = Statement::make_assignment(lhs, sum, loc);
then_block->add_statement(s);
Block* else_block = new Block(iter_init, loc);
ref = this->make_range_ref(range_object, range_temp, loc);
index_ref = Expression::make_temporary_reference(index_temp, loc);
call = Runtime::make_call(Runtime::DECODERUNE, loc, 2, ref, index_ref);
value_ref = Expression::make_temporary_reference(value_temp, loc);
value_ref->set_is_lvalue();
Expression* res = Expression::make_call_result(call, 0);
s = Statement::make_assignment(value_ref, res, loc);
else_block->add_statement(s);
lhs = Expression::make_temporary_reference(next_index_temp, loc);
lhs->set_is_lvalue();
res = Expression::make_call_result(call, 1);
s = Statement::make_assignment(lhs, res, loc);
else_block->add_statement(s);
s = Statement::make_if_statement(cond, then_block, else_block, loc);
iter_init->add_statement(s);
*piter_init = iter_init;
// Set *PPOST to
// index_temp = next_index_temp
Block* post = new Block(enclosing, loc);
index_ref = Expression::make_temporary_reference(index_temp, loc);
index_ref->set_is_lvalue();
ref = Expression::make_temporary_reference(next_index_temp, loc);
s = Statement::make_assignment(index_ref, ref, loc);
post->add_statement(s);
*ppost = post;
}
// Lower a for range over a map.
void
For_range_statement::lower_range_map(Gogo* gogo,
Map_type* map_type,
Block* enclosing,
Block* body_block,
Named_object* range_object,
Temporary_statement* range_temp,
Temporary_statement* index_temp,
Temporary_statement* value_temp,
Block** pinit,
Expression** pcond,
Block** piter_init,
Block** ppost)
{
Location loc = this->location();
// The runtime uses a struct to handle ranges over a map. The
// struct is built by Map_type::hiter_type for a specific map type.
// The loop we generate:
// var hiter map_iteration_struct
// for mapiterinit(type, range, &hiter); hiter.key != nil; mapiternext(&hiter) {
// index_temp = *hiter.key
// value_temp = *hiter.val
// index = index_temp
// value = value_temp
// original body
// }
// Set *PINIT to
// var hiter map_iteration_struct
// runtime.mapiterinit(type, range, &hiter)
Block* init = new Block(enclosing, loc);
Type* map_iteration_type = map_type->hiter_type(gogo);
Temporary_statement* hiter = Statement::make_temporary(map_iteration_type,
NULL, loc);
init->add_statement(hiter);
Expression* p1 = Expression::make_type_descriptor(map_type, loc);
Expression* p2 = this->make_range_ref(range_object, range_temp, loc);
Expression* ref = Expression::make_temporary_reference(hiter, loc);
Expression* p3 = Expression::make_unary(OPERATOR_AND, ref, loc);
Expression* call = Runtime::make_call(Runtime::MAPITERINIT, loc, 3,
p1, p2, p3);
init->add_statement(Statement::make_statement(call, true));
*pinit = init;
// Set *PCOND to
// hiter.key != nil
ref = Expression::make_temporary_reference(hiter, loc);
ref = Expression::make_field_reference(ref, 0, loc);
Expression* ne = Expression::make_binary(OPERATOR_NOTEQ, ref,
Expression::make_nil(loc),
loc);
*pcond = ne;
// Set *PITER_INIT to
// index_temp = *hiter.key
// value_temp = *hiter.val
Block* iter_init = new Block(body_block, loc);
Expression* lhs = Expression::make_temporary_reference(index_temp, loc);
Expression* rhs = Expression::make_temporary_reference(hiter, loc);
rhs = Expression::make_field_reference(ref, 0, loc);
rhs = Expression::make_dereference(ref, Expression::NIL_CHECK_NOT_NEEDED,
loc);
Statement* set = Statement::make_assignment(lhs, rhs, loc);
iter_init->add_statement(set);
if (value_temp != NULL)
{
lhs = Expression::make_temporary_reference(value_temp, loc);
rhs = Expression::make_temporary_reference(hiter, loc);
rhs = Expression::make_field_reference(rhs, 1, loc);
rhs = Expression::make_dereference(rhs, Expression::NIL_CHECK_NOT_NEEDED,
loc);
set = Statement::make_assignment(lhs, rhs, loc);
iter_init->add_statement(set);
}
*piter_init = iter_init;
// Set *PPOST to
// mapiternext(&hiter)
Block* post = new Block(enclosing, loc);
ref = Expression::make_temporary_reference(hiter, loc);
p1 = Expression::make_unary(OPERATOR_AND, ref, loc);
call = Runtime::make_call(Runtime::MAPITERNEXT, loc, 1, p1);
post->add_statement(Statement::make_statement(call, true));
*ppost = post;
}
// Lower a for range over a channel.
void
For_range_statement::lower_range_channel(Gogo*,
Block*,
Block* body_block,
Named_object* range_object,
Temporary_statement* range_temp,
Temporary_statement* index_temp,
Temporary_statement* value_temp,
Block** pinit,
Expression** pcond,
Block** piter_init,
Block** ppost)
{
go_assert(value_temp == NULL);
Location loc = this->location();
// The loop we generate:
// for {
// index_temp, ok_temp = <-range
// if !ok_temp {
// break
// }
// index = index_temp
// original body
// }
// We have no initialization code, no condition, and no post code.
*pinit = NULL;
*pcond = NULL;
*ppost = NULL;
// Set *PITER_INIT to
// index_temp, ok_temp = <-range
// if !ok_temp {
// break
// }
Block* iter_init = new Block(body_block, loc);
Temporary_statement* ok_temp =
Statement::make_temporary(Type::lookup_bool_type(), NULL, loc);
iter_init->add_statement(ok_temp);
Expression* cref = this->make_range_ref(range_object, range_temp, loc);
Temporary_reference_expression* iref =
Expression::make_temporary_reference(index_temp, loc);
iref->set_is_lvalue();
Temporary_reference_expression* oref =
Expression::make_temporary_reference(ok_temp, loc);
oref->set_is_lvalue();
Statement* s = Statement::make_tuple_receive_assignment(iref, oref, cref,
loc);
iter_init->add_statement(s);
Block* then_block = new Block(iter_init, loc);
s = Statement::make_break_statement(this->break_label(), loc);
then_block->add_statement(s);
oref = Expression::make_temporary_reference(ok_temp, loc);
Expression* cond = Expression::make_unary(OPERATOR_NOT, oref, loc);
s = Statement::make_if_statement(cond, then_block, NULL, loc);
iter_init->add_statement(s);
*piter_init = iter_init;
}
// Match
//
// for k := range m { delete(m, k) }
//
// Lower it to runtime.mapclear(TYPE, m) on match, return the statement
// containing the call. Return NULL otherwise.
Statement*
For_range_statement::lower_map_range_clear(Type* map_type,
Block* enclosing,
Expression* orig_range_expr,
Named_object* range_object,
Temporary_statement* range_temp,
Location loc)
{
if (this->value_var_ != NULL)
return NULL;
if (this->index_var_ == NULL)
return NULL;
// Require the loop index be a new variable. We cannot rewrite
// if it is used outside of the loop.
Var_expression* index_ve = this->index_var_->var_expression();
if (index_ve == NULL)
return NULL;
Named_object* index_no = index_ve->named_object();
if (enclosing->bindings()->lookup_local(index_no->name()) != index_no)
return NULL;
// Match the body, a single call statement delete(m, k).
const std::vector<Statement*>* statements = this->statements_->statements();
if (statements->size() != 1)
return NULL;
Expression_statement* es = statements->at(0)->expression_statement();
if (es == NULL)
return NULL;
Call_expression* call = es->expr()->call_expression();
if (call == NULL || !call->is_builtin()
|| call->builtin_call_expression()->code()
!= Builtin_call_expression::BUILTIN_DELETE)
return NULL;
if (!Expression::is_same_variable(call->args()->at(0), orig_range_expr)
|| !Expression::is_same_variable(call->args()->at(1), this->index_var_))
return NULL;
// Everything matches. Rewrite to mapclear(TYPE, MAP).
Expression* e1 = Expression::make_type_descriptor(map_type, loc);
Expression* e2 = this->make_range_ref(range_object, range_temp, loc);
call = Runtime::make_call(Runtime::MAPCLEAR, loc, 2, e1, e2);
return Statement::make_statement(call, true);
}
// Match
//
// for i := range a { a[i] = zero }
//
// Lower it to call memclr on match, and return the statement. Return
// NULL otherwise.
Statement*
For_range_statement::lower_array_range_clear(Gogo* gogo,
Type* array_type,
Expression* orig_range_expr,
Block* temp_block,
Named_object* range_object,
Temporary_statement* range_temp,
Location loc)
{
if (this->value_var_ != NULL)
return NULL;
if (this->index_var_ == NULL)
return NULL;
// Match the body, a single assignment statement a[i] = zero.
const std::vector<Statement*>* statements = this->statements_->statements();
if (statements->size() != 1)
return NULL;
Assignment_statement* as = statements->at(0)->assignment_statement();
if (as == NULL || !as->rhs()->is_zero_value())
return NULL;
if (as->lhs()->type()->interface_type() != NULL
&& as->rhs()->type()->interface_type() == NULL
&& !as->rhs()->type()->is_nil_type())
// Implicit type conversion may change a zero value to non-zero, like
// interface{}(0).
return NULL;
Array_index_expression* aie = as->lhs()->array_index_expression();
if (aie == NULL || aie->end() != NULL
|| !Expression::is_same_variable(orig_range_expr, aie->array())
|| !Expression::is_same_variable(this->index_var_, aie->start()))
return NULL;
// Everything matches. Rewrite to
//
// if len(a) != 0 {
// tmp1 = &a[0]
// tmp2 = len(a)*sizeof(elem(a))
// memclr{NoHeap,Has}Pointers(tmp1, tmp2)
// i = len(a) - 1
// }
Type* elem_type = array_type->array_type()->element_type();
int64_t elme_sz;
bool ok = elem_type->backend_type_size(gogo, &elme_sz);
if (!ok)
return NULL;
Block* b = new Block(temp_block, loc);
Expression* ref;
if (range_object == NULL && range_temp == NULL)
// is_same_variable implies no side effect, so it is ok to copy.
ref = orig_range_expr->copy();
else
ref = this->make_range_ref(range_object, range_temp, loc);
Expression* len = this->call_builtin(gogo, "len", ref, loc);
Temporary_statement* tslen = Statement::make_temporary(NULL, len, loc);
temp_block->add_statement(tslen);
Expression* zero = Expression::make_integer_ul(0, this->index_var_->type(), loc);
ref = ref->copy();
Expression* elem = Expression::make_array_index(ref, zero, NULL, NULL, loc);
elem->array_index_expression()->set_needs_bounds_check(false);
Expression* e1 = Expression::make_unary(OPERATOR_AND, elem, loc);
Temporary_statement* ts1 = Statement::make_temporary(NULL, e1, loc);
b->add_statement(ts1);
len = Expression::make_temporary_reference(tslen, loc);
Expression* sz = Expression::make_integer_int64(elme_sz, len->type(), loc);
Expression* e2 = Expression::make_binary(OPERATOR_MULT, len, sz, loc);
Temporary_statement* ts2 = Statement::make_temporary(NULL, e2, loc);
b->add_statement(ts2);
Expression* ptr_arg = Expression::make_temporary_reference(ts1, loc);
Expression* sz_arg = Expression::make_temporary_reference(ts2, loc);
Expression* call;
if (elem_type->has_pointer())
call = Runtime::make_call(Runtime::MEMCLRHASPTR, loc, 2, ptr_arg, sz_arg);
else
{
Type* int32_type = Type::lookup_integer_type("int32");
Expression* zero32 = Expression::make_integer_ul(0, int32_type, loc);
call = Runtime::make_call(Runtime::BUILTIN_MEMSET, loc, 3, ptr_arg,
zero32, sz_arg);
}
Statement* cs3 = Statement::make_statement(call, true);
b->add_statement(cs3);
len = Expression::make_temporary_reference(tslen, loc);
Expression* one = Expression::make_integer_ul(1, len->type(), loc);
Expression* rhs = Expression::make_binary(OPERATOR_MINUS, len, one, loc);
Expression* lhs = this->index_var_->copy();
Statement* as4 = Statement::make_assignment(lhs, rhs, loc);
b->add_statement(as4);
len = Expression::make_temporary_reference(tslen, loc);
zero = zero->copy();
Expression* cond = Expression::make_binary(OPERATOR_NOTEQ, len, zero, loc);
return Statement::make_if_statement(cond, b, NULL, loc);
}
// Return the break LABEL_EXPR.
Unnamed_label*
For_range_statement::break_label()
{
if (this->break_label_ == NULL)
this->break_label_ = new Unnamed_label(this->location());
return this->break_label_;
}
// Return the continue LABEL_EXPR.
Unnamed_label*
For_range_statement::continue_label()
{
if (this->continue_label_ == NULL)
this->continue_label_ = new Unnamed_label(this->location());
return this->continue_label_;
}
// Dump the AST representation for a for range statement.
void
For_range_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->ostream() << "for ";
ast_dump_context->dump_expression(this->index_var_);
if (this->value_var_ != NULL)
{
ast_dump_context->ostream() << ", ";
ast_dump_context->dump_expression(this->value_var_);
}
ast_dump_context->ostream() << " = range ";
ast_dump_context->dump_expression(this->range_);
if (ast_dump_context->dump_subblocks())
{
ast_dump_context->ostream() << " {" << std::endl;
ast_dump_context->indent();
ast_dump_context->dump_block(this->statements_);
ast_dump_context->unindent();
ast_dump_context->print_indent();
ast_dump_context->ostream() << "}";
}
ast_dump_context->ostream() << dsuffix(location()) << std::endl;
}
// Make a for statement with a range clause.
For_range_statement*
Statement::make_for_range_statement(Expression* index_var,
Expression* value_var,
Expression* range,
Location location)
{
return new For_range_statement(index_var, value_var, range, location);
}