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//===-- go-llvm-materialize.cpp - Llvm_backend materalize* methods -------===//
//
// Copyright 2018 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.
//
//===----------------------------------------------------------------------===//
//
// Llvm_backend methods relating to materialization of llvm values.
//
//===----------------------------------------------------------------------===//
#include "go-llvm.h"
#include "go-llvm-builtins.h"
#include "go-c.h"
#include "go-system.h"
#include "go-llvm-cabi-oracle.h"
#include "go-llvm-irbuilders.h"
#include "gogo.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/DIBuilder.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Value.h"
Bexpression *Llvm_backend::materializeIndirect(Bexpression *indExpr, bool isLHS)
{
Location location = indExpr->location();
Btype *btype = indExpr->btype();
std::vector<Bexpression *> iexprs =
nbuilder_.extractChildenAndDestroy(indExpr);
assert(iexprs.size() == 1);
Bexpression *expr = iexprs[0];
// Handle cases such as
//
// *(*sometype)(unsafe.Pointer(uintptr(<constant>))) = ...
//
// where we have a LHS expression intended to cause a crash or fault.
if (isLHS && !expr->varExprPending()) {
Bexpression *rval = nbuilder_.mkDeref(btype, expr->value(), expr,
location);
return rval;
}
const VarContext *vc = nullptr;
if (expr->varExprPending()) {
vc = &expr->varContext();
// handle *&x
if (vc->addrLevel() != 0) {
Bexpression *rval = nbuilder_.mkDeref(btype, expr->value(), expr,
location);
rval->setVarExprPending(vc->lvalue(), vc->addrLevel() - 1);
return rval;
}
}
std::string tag(expr->tag().size() == 0 ? "deref" : expr->tag());
Bexpression *rval = genLoad(expr, btype, location, tag);
if (vc) {
if (rval->varExprPending())
rval->resetVarExprContext();
rval->setVarExprPending(expr->varContext());
}
return rval;
}
Bexpression *Llvm_backend::materializeAddress(Bexpression *addrExpr)
{
Location location = addrExpr->location();
std::vector<Bexpression *> aexprs =
nbuilder_.extractChildenAndDestroy(addrExpr);
Bexpression *bexpr = aexprs[0];
assert(aexprs.size() == 1);
assert(bexpr->value());
// Gofrontend tends to take the address of things that are already
// pointer-like to begin with (for example, C strings and and
// arrays). This presents wrinkles here, since an array type
// in LLVM is already effectively a pointer (you can feed it
// directly into a GEP as opposed to having to take the address of
// it first). Bypass the effects of the address operator if
// this is the case. This is hacky, maybe I can come up with a
// better solution for this issue(?).
if (llvm::isa<llvm::ConstantArray>(bexpr->value()))
return bexpr;
if (bexpr->value()->getType() == stringType()->type() &&
bexpr->isConstant())
return bexpr;
// If the value we're trying to take the address of is a composite
// constant, we have to spill it to memory here in order for us to
// take its address.
llvm::Value *val = bexpr->value();
if (bexpr->isConstant()) {
llvm::Constant *cval = llvm::cast<llvm::Constant>(val);
Bvariable *cv = genVarForConstant(cval, bexpr->btype());
val = cv->value();
}
// When using non-integral pointers, the Go pointer types (Btype)
// are in address space 1. Local variables (allocas) are always
// in address space 0. We need to insert a cast if we are taking
// the address of a local variable.
llvm::Type *valtyp = val->getType();
assert(valtyp->isPointerTy());
if (valtyp->getPointerAddressSpace() != addressSpace_) {
llvm::Type *typ =
llvm::PointerType::get(valtyp->getPointerElementType(),
addressSpace_);
val = new llvm::AddrSpaceCastInst(val, typ, "ascast");
}
// Create new expression with proper type.
Btype *pt = pointer_type(bexpr->btype());
Bexpression *rval = nbuilder_.mkAddress(pt, val, bexpr, location);
std::string adtag(bexpr->tag());
adtag += ".ad";
rval->setTag(adtag);
const VarContext &vc = bexpr->varContext();
rval->setVarExprPending(vc.lvalue(), vc.addrLevel() + 1);
return rval;
}
Bexpression *Llvm_backend::materializeConversion(Bexpression *convExpr)
{
Location location = convExpr->location();
Btype *type = convExpr->btype();
std::vector<Bexpression *> iexprs =
nbuilder_.extractChildenAndDestroy(convExpr);
assert(iexprs.size() == 1);
Bexpression *expr = iexprs[0];
// For composite-init-pending values, materialize a variable now.
if (expr->compositeInitPending()) {
assert(!expr->varExprPending());
expr = resolveCompositeInit(expr, nullptr);
}
llvm::Value *val = expr->value();
assert(val);
llvm::Type *valType = val->getType();
llvm::Type *toType = type->type();
// In the varexpr pending case, decide what to do depending on whether
// the var is in an lvalue or rvalue context. For something like
//
// var y int32
// z = int64(y)
//
// we want to force the load of "y" before converting to int64. For
// an lvalue context, the conversion will be applied to the pointed-to-type
// as well as the value type.
if (expr->varExprPending()) {
bool lvalue = expr->varContext().lvalue();
if (!lvalue) {
expr = resolveVarContext(expr);
val = expr->value();
valType = val->getType();
}
if (lvalue || useCopyForLoadStore(type->type())) {
llvm::Type *et = expr->btype()->type();
if (valType->isPointerTy() &&
valType->getPointerElementType() == et)
toType = llvm::PointerType::get(toType, addressSpace_);
}
}
// If we're converting between two different Btypes that have the
// same underlying LLVM type, then we can create a new Bexpression
// for the conversion but not do anything else.
if (toType == valType) {
Bexpression *rval =
nbuilder_.mkConversion(type, expr->value(), expr, location);
if (expr->varExprPending())
rval->setVarExprPending(expr->varContext());
return rval;
}
// If we're applying a conversion to an aggregate constant, call a helper to
// see if we can create a new (but equivalent) constant value using the target
// type. If this works, we're effectively done. If the conversion doesn't
// succeed, materialize a variable containing the constant and apply the
// conversion to the variable's type (which will be a pointer to the type of
// the constant), then flag the result as "load pending".
bool pending = false;
if (expr->isConstant() && val->getType()->isAggregateType()) {
llvm::Constant *cval = llvm::cast<llvm::Constant>(val);
assert(valType == cval->getType());
llvm::Value *convertedValue = genConvertedConstant(cval, toType);
if (convertedValue != nullptr) {
// We have a new value of the correct type. Wrap a conversion
// expr around it and return.
return nbuilder_.mkConversion(type, convertedValue, expr, location);
}
// materialize constant into variable.
Bvariable *cv = genVarForConstant(cval, expr->btype());
val = cv->value();
valType = val->getType();
toType = llvm::PointerType::get(toType, addressSpace_);
pending = true;
}
Bexpression *rval = nullptr;
LIRBuilder builder(context_, llvm::ConstantFolder());
// Pointer type to pointer-sized-integer type. Comes up when
// converting function pointer to function descriptor (during
// creation of function descriptor vals) or constant array to
// uintptr (as part of GC symbol initializer creation), and in other
// places in FE-generated code (ex: array index checks).
if (valType->isPointerTy() && toType == llvmIntegerType()) {
if (val->getType()->getPointerAddressSpace() != 0) {
// We are using non-integral pointer. Cast to address space 0
// before casting to int.
llvm::Type *et = val->getType()->getPointerElementType();
llvm::Type *pt = llvm::PointerType::get(et, 0);
std::string tname(namegen("ascast"));
val = builder.CreateAddrSpaceCast(val, pt, tname);
expr = nbuilder_.mkConversion(type, val, expr, location);
}
std::string tname(namegen("pticast"));
llvm::Value *pticast = builder.CreatePtrToInt(val, toType, tname);
rval = nbuilder_.mkConversion(type, pticast, expr, location);
}
// Pointer-sized-integer type to pointer type. This comes up
// in type hash/compare functions.
if (toType->isPointerTy() && valType == llvmIntegerType()) {
llvm::Type *pt = toType;
if (toType->getPointerAddressSpace() != 0) {
// We are using non-integral pointer. Cast to address space 0
// first.
llvm::Type *et = toType->getPointerElementType();
pt = llvm::PointerType::get(et, 0);
}
std::string tname(namegen("itpcast"));
llvm::Value *itpcast = builder.CreateIntToPtr(val, pt, tname);
rval = nbuilder_.mkConversion(type, itpcast, expr, location);
if (pt != toType) {
std::string tname(namegen("ascast"));
llvm::Value *ascast = builder.CreateAddrSpaceCast(itpcast, toType, tname);
rval = nbuilder_.mkConversion(type, ascast, rval, location);
}
}
// For pointer conversions (ex: *int32 => *int64) create an
// appropriate bitcast.
if (valType->isPointerTy() && toType->isPointerTy()) {
std::string tag(namegen("cast"));
llvm::Value *bitcast = builder.CreatePointerBitCastOrAddrSpaceCast(val, toType, tag);
rval = nbuilder_.mkConversion(type, bitcast, expr, location);
}
// Integer-to-integer conversions
// FIXME: the type of the the operand could be AuxT, which we use
// to wrap an LLVM type for intrinsics. Assume it is signed for now.
// If this turns to be an issue, we should define the correct Btype
// for intrinsics.
if (valType->isIntegerTy() && toType->isIntegerTy()) {
llvm::IntegerType *valIntTyp =
llvm::cast<llvm::IntegerType>(valType);
llvm::IntegerType *toIntTyp =
llvm::cast<llvm::IntegerType>(toType);
unsigned valbits = valIntTyp->getBitWidth();
unsigned tobits = toIntTyp->getBitWidth();
llvm::Value *conv = nullptr;
if (tobits > valbits) {
if (expr->btype()->type() == llvmBoolType() ||
(expr->btype()->castToBIntegerType() &&
expr->btype()->castToBIntegerType()->isUnsigned()))
conv = builder.CreateZExt(val, toType, namegen("zext"));
else
conv = builder.CreateSExt(val, toType, namegen("sext"));
} else {
conv = builder.CreateTrunc(val, toType, namegen("trunc"));
}
rval = nbuilder_.mkConversion(type, conv, expr, location);
}
// Float -> float conversions
if (toType->isFloatingPointTy() && valType->isFloatingPointTy()) {
llvm::Value *conv = nullptr;
if (toType == llvmFloatType() && valType == llvmDoubleType())
conv = builder.CreateFPTrunc(val, toType, namegen("fptrunc"));
else if (toType == llvmDoubleType() && valType == llvmFloatType())
conv = builder.CreateFPExt(val, toType, namegen("fpext"));
else
assert(0 && "unexpected float type");
rval = nbuilder_.mkConversion(type, conv, expr, location);
}
// Float -> integer conversions
if (toType->isIntegerTy() && valType->isFloatingPointTy()) {
llvm::Value *conv = nullptr;
if (type->castToBIntegerType()->isUnsigned())
conv = builder.CreateFPToUI(val, toType, namegen("ftoui"));
else
conv = builder.CreateFPToSI(val, toType, namegen("ftosi"));
rval = nbuilder_.mkConversion(type, conv, expr, location);
}
// Integer -> float conversions
if (toType->isFloatingPointTy() && valType->isIntegerTy()) {
llvm::Value *conv = nullptr;
if (expr->btype()->castToBIntegerType() &&
expr->btype()->castToBIntegerType()->isUnsigned())
conv = builder.CreateUIToFP(val, toType, namegen("uitof"));
else
conv = builder.CreateSIToFP(val, toType, namegen("sitof"));
rval = nbuilder_.mkConversion(type, conv, expr, location);
}
if (!rval)
// This case not handled.
assert(false && "this flavor of conversion not handled");
// Propagate pending var context if we didn't resolve it here.
// This may happen for composite values.
if (expr->varExprPending())
rval->setVarExprPending(expr->varContext());
else if (pending)
rval->setVarExprPending(false, 0);
return rval;
}
llvm::Value *Llvm_backend::makePointerOffsetGEP(llvm::PointerType *llpt,
llvm::Value *idxval,
llvm::Value *sptr)
{
LIRBuilder builder(context_, llvm::ConstantFolder());
llvm::SmallVector<llvm::Value *, 1> elems(1);
elems[0] = idxval;
llvm::Value *val = builder.CreateGEP(llpt->getElementType(), sptr, elems, namegen("ptroff"));
return val;
}
llvm::Value *Llvm_backend::makeArrayIndexGEP(llvm::ArrayType *llat,
llvm::Value *idxval,
llvm::Value *sptr)
{
LIRBuilder builder(context_, llvm::ConstantFolder());
llvm::SmallVector<llvm::Value *, 2> elems(2);
elems[0] = llvm::ConstantInt::get(llvmInt32Type(), 0);
elems[1] = idxval;
llvm::Value *val = builder.CreateGEP(llat, sptr, elems, namegen("index"));
return val;
}
llvm::Value *Llvm_backend::makeFieldGEP(llvm::StructType *llst,
unsigned fieldIndex,
llvm::Value *sptr)
{
assert(sptr->getType()->isPointerTy());
llvm::PointerType *srcTyp = llvm::cast<llvm::PointerType>(sptr->getType());
assert(srcTyp->getElementType()->isStructTy());
LIRBuilder builder(context_, llvm::ConstantFolder());
assert(fieldIndex < llst->getNumElements());
std::string tag(namegen("field"));
llvm::Value *val =
builder.CreateConstInBoundsGEP2_32(llst, sptr, 0, fieldIndex, tag);
return val;
}
Bexpression *Llvm_backend::materializeStructField(Bexpression *fieldExpr)
{
Location location = fieldExpr->location();
const std::string ftag(fieldExpr->tag());
unsigned index = fieldExpr->fieldIndex();
std::vector<Bexpression *> fexprs =
nbuilder_.extractChildenAndDestroy(fieldExpr);
assert(fexprs.size() == 1);
Bexpression *bstruct = fexprs[0];
if (bstruct->compositeInitPending())
bstruct = resolveCompositeInit(bstruct, nullptr);
// Construct an appropriate GEP
llvm::Type *llt = bstruct->btype()->type();
assert(llt->isStructTy());
llvm::StructType *llst = llvm::cast<llvm::StructType>(llt);
llvm::Value *sval = bstruct->value();
llvm::Value *fval;
if (bstruct->isConstant())
fval = llvm::cast<llvm::Constant>(sval)->getAggregateElement(index);
else
fval = makeFieldGEP(llst, index, sval);
Btype *bft = elementTypeByIndex(bstruct->btype(), index);
// Wrap result in a Bexpression
Bexpression *rval = nbuilder_.mkStructField(bft, fval, bstruct,
index, location);
if (bstruct->varExprPending())
rval->setVarExprPending(bstruct->varContext());
std::string tag(bstruct->tag());
tag += (ftag.empty() ? ".field" : ftag);
rval->setTag(tag);
// We're done
return rval;
}
Bexpression *Llvm_backend::materializeCompound(Bexpression *comExpr)
{
Location location = comExpr->location();
std::vector<Bnode *> kids = nbuilder_.extractChildNodesAndDestroy(comExpr);
assert(kids.size() == 2);
Bstatement *bstat = kids[0]->castToBstatement();
assert(bstat);
Bexpression *bexpr = kids[1]->castToBexpression();
assert(bexpr);
bexpr = materialize(bexpr);
// Compound expressions can be used to produce lvalues, so we don't
// want to call resolve() on bexpr here.
// But we do want to resolve composite init.
if (bexpr->compositeInitPending())
bexpr = resolveCompositeInit(bexpr, nullptr);
Bexpression *rval = nbuilder_.mkCompound(bstat, bexpr, bexpr->value(),
location);
if (bexpr->varExprPending())
rval->setVarExprPending(bexpr->varContext());
return rval;
}
Bexpression *Llvm_backend::materializeConditional(Bexpression *condExpr)
{
Bfunction *function = condExpr->getFunction();
Location location = condExpr->location();
Btype *btype = condExpr->btype();
std::vector<Bexpression *> cexprs =
nbuilder_.extractChildenAndDestroy(condExpr);
assert(cexprs.size() == 2 || cexprs.size() == 3);
Bexpression *condition = cexprs[0];
Bexpression *then_expr = cexprs[1];
Bexpression *else_expr = (cexprs.size() == 3 ? cexprs[2] : nullptr);
condition = resolveVarContext(condition);
then_expr = resolve(then_expr);
if (else_expr)
else_expr = resolve(else_expr);
std::vector<Bvariable *> novars;
Bblock *thenBlock = nbuilder_.mkBlock(function, novars, location);
Bblock *elseBlock = nullptr;
Bvariable *tempv = nullptr;
// FIXME: add lifetime intrinsics for temp var below.
Bstatement *thenStmt = nullptr;
if (!btype || then_expr->btype() == void_type())
thenStmt = expression_statement(function, then_expr);
else
tempv = temporary_variable(function, nullptr,
btype, then_expr, false,
location, &thenStmt);
nbuilder_.addStatementToBlock(thenBlock, thenStmt);
if (else_expr) {
Bstatement *elseStmt = nullptr;
elseBlock = nbuilder_.mkBlock(function, novars, location);
if (!btype || btype == void_type() || else_expr->btype() == void_type()) {
elseStmt = expression_statement(function, else_expr);
} else {
// Capture "else_expr" into temporary. Type needs to agree with
// then_expr if then_expr had non-void type.
if (!tempv) {
tempv = temporary_variable(function, nullptr,
btype, else_expr, false,
location, &elseStmt);
} else {
// Ideally it would be nice to assert that the types are
// identical for if_expr and else_expr, but particularly for
// pointer types we need to allow for some disagreement (ex:
// nil_pointer_expression, which is untyped/polymorphic).
// Assume that the type checking in the call to
// assignment_statement will catch any problems.
Bexpression *varExpr = var_expression(tempv, location);
elseStmt = assignment_statement(function, varExpr, else_expr, location);
}
}
nbuilder_.addStatementToBlock(elseBlock, elseStmt);
}
// Wrap up and return the result
Bstatement *ifStmt = if_statement(function, condition,
thenBlock, elseBlock, location);
Bexpression *rval = (tempv ?
var_expression(tempv, location) :
nbuilder_.mkVoidValue(void_type()));
Bexpression *result =
materialize(compound_expression(ifStmt, rval, location));
return result;
}
Bexpression *Llvm_backend::materializeUnary(Bexpression *unExpr)
{
Operator op = unExpr->op();
Location location = unExpr->location();
std::vector<Bexpression *> uexprs =
nbuilder_.extractChildenAndDestroy(unExpr);
assert(uexprs.size() == 1);
Bexpression *expr = uexprs[0];
expr = resolveVarContext(expr);
Btype *bt = expr->btype();
switch (op) {
case OPERATOR_MINUS: {
assert(false && "should have been expanded away");
break;
}
case OPERATOR_NOT: {
LIRBuilder builder(context_, llvm::ConstantFolder());
assert(isBooleanType(bt));
// FIXME: is this additional compare-to-zero needed? Or can we be certain
// that the value in question has a single bit set?
Bexpression *bzero = zero_expression(bt);
llvm::Value *cmp =
builder.CreateICmpNE(expr->value(), bzero->value(), namegen("icmp"));
Btype *lbt = makeAuxType(llvmBoolType());
Bexpression *cmpex =
nbuilder_.mkBinaryOp(OPERATOR_EQEQ, lbt, cmp, bzero, expr, location);
llvm::Constant *one = llvm::ConstantInt::get(llvmBoolType(), 1);
llvm::Value *xorex = builder.CreateXor(cmp, one, namegen("xor"));
Bexpression *notex = nbuilder_.mkUnaryOp(op, lbt, xorex, cmpex, location);
Bexpression *tobool = lateConvert(bool_type(), notex, location);
return tobool;
}
case OPERATOR_XOR: {
// ^x bitwise complement is m ^ x with m = "all bits set to 1"
// for unsigned x and m = -1 for signed x
assert(bt->type()->isIntegerTy());
LIRBuilder builder(context_, llvm::ConstantFolder());
llvm::Value *onesval = llvm::Constant::getAllOnesValue(bt->type());
llvm::Value *xorExpr = builder.CreateXor(expr->value(), onesval,
namegen("xor"));
Bexpression *rval = nbuilder_.mkUnaryOp(op, bt, xorExpr, expr, location);
return rval;
break;
}
default:
assert(false && "unexpected unary opcode");
}
return nullptr;
}
static llvm::CmpInst::Predicate compare_op_to_pred(Operator op,
llvm::Type *typ,
bool isUnsigned)
{
bool isFloat = typ->isFloatingPointTy();
if (isFloat) {
switch (op) {
case OPERATOR_EQEQ:
return llvm::CmpInst::Predicate::FCMP_OEQ;
case OPERATOR_NOTEQ:
return llvm::CmpInst::Predicate::FCMP_UNE;
case OPERATOR_LT:
return llvm::CmpInst::Predicate::FCMP_OLT;
case OPERATOR_LE:
return llvm::CmpInst::Predicate::FCMP_OLE;
case OPERATOR_GT:
return llvm::CmpInst::Predicate::FCMP_OGT;
case OPERATOR_GE:
return llvm::CmpInst::Predicate::FCMP_OGE;
default:
break;
}
} else {
switch (op) {
case OPERATOR_EQEQ:
return llvm::CmpInst::Predicate::ICMP_EQ;
case OPERATOR_NOTEQ:
return llvm::CmpInst::Predicate::ICMP_NE;
case OPERATOR_LT:
return (isUnsigned ? llvm::CmpInst::Predicate::ICMP_ULT
: llvm::CmpInst::Predicate::ICMP_SLT);
case OPERATOR_LE:
return (isUnsigned ? llvm::CmpInst::Predicate::ICMP_ULE
: llvm::CmpInst::Predicate::ICMP_SLE);
case OPERATOR_GT:
return (isUnsigned ? llvm::CmpInst::Predicate::ICMP_UGT
: llvm::CmpInst::Predicate::ICMP_SGT);
case OPERATOR_GE:
return (isUnsigned ? llvm::CmpInst::Predicate::ICMP_UGE
: llvm::CmpInst::Predicate::ICMP_SGE);
default:
break;
}
}
assert(false);
return llvm::CmpInst::BAD_ICMP_PREDICATE;
}
std::pair<llvm::Value *, llvm::Value *>
Llvm_backend::convertForBinary(Operator op,
Bexpression *left,
Bexpression *right)
{
llvm::Value *leftVal = left->value();
llvm::Value *rightVal = right->value();
std::pair<llvm::Value *, llvm::Value *> rval =
std::make_pair(leftVal, rightVal);
llvm::Type *leftType = leftVal->getType();
llvm::Type *rightType = rightVal->getType();
if (leftType == rightType)
return rval;
// Case 1: nil op X
if (llvm::isa<llvm::ConstantPointerNull>(leftVal) &&
rightType->isPointerTy()) {
BexprLIRBuilder builder(context_, left);
std::string tag(namegen("cast"));
llvm::Value *bitcast = builder.CreateBitCast(leftVal, rightType, tag);
rval.first = bitcast;
return rval;
}
// Case 2: X op nil
if (llvm::isa<llvm::ConstantPointerNull>(rightVal) &&
leftType->isPointerTy()) {
BexprLIRBuilder builder(context_, right);
std::string tag(namegen("cast"));
llvm::Value *bitcast = builder.CreateBitCast(rightVal, leftType, tag);
rval.second = bitcast;
return rval;
}
// Case 3: shift with different sized operands (ex: int64(v) << uint8(3)).
// Promote or demote shift amount operand to match width of left operand.
if ((op == OPERATOR_LSHIFT || op == OPERATOR_RSHIFT) &&
leftType != rightType) {
BexprLIRBuilder builder(context_, right);
llvm::IntegerType *leftITyp = llvm::cast<llvm::IntegerType>(leftType);
llvm::IntegerType *rightITyp = llvm::cast<llvm::IntegerType>(rightType);
llvm::Value *conv = nullptr;
if (leftITyp->getBitWidth() > rightITyp->getBitWidth())
conv = builder.CreateZExt(rightVal, leftType, namegen("zext"));
else
conv = builder.CreateTrunc(rightVal, leftType, namegen("trunc"));
rval.second = conv;
return rval;
}
// Case 4: pointer type comparison
// We check that if both are pointer types and pointing to the same type,
// insert a cast (it doesn't matter we cast which one). This mostly needed
// for circular pointer types (ex: type T *T; var p, q T; p == &q), where
// the two sides have semantically identical types but with different
// representations (in this case, T vs. *T).
if (leftType->isPointerTy() && rightType->isPointerTy()) {
BPointerType *lbpt = left->btype()->castToBPointerType();
BPointerType *rbpt = right->btype()->castToBPointerType();
if (lbpt->toType()->type() == rbpt->toType()->type()) {
BexprLIRBuilder builder(context_, right);
std::string tag(namegen("cast"));
llvm::Value *bitcast = builder.CreateBitCast(rightVal, leftType, tag);
rval.second = bitcast;
return rval;
}
}
return rval;
}
Bexpression *Llvm_backend::materializeBinary(Bexpression *binExpr)
{
Operator op = binExpr->op();
Location location = binExpr->location();
std::vector<Bexpression *> bexprs =
nbuilder_.extractChildenAndDestroy(binExpr);
assert(bexprs.size() == 2);
Bexpression *left = bexprs[0];
Bexpression *right = bexprs[1];
Btype *bltype = left->btype();
Btype *brtype = right->btype();
left = resolveVarContext(left);
right = resolveVarContext(right);
assert(left->value() && right->value());
std::pair<llvm::Value *, llvm::Value *> converted =
convertForBinary(op, left, right);
llvm::Value *leftVal = converted.first;
llvm::Value *rightVal = converted.second;
llvm::Type *ltype = leftVal->getType();
llvm::Type *rtype = rightVal->getType();
assert(ltype == rtype);
BIntegerType *blitype = bltype->castToBIntegerType();
BIntegerType *britype = brtype->castToBIntegerType();
assert((blitype == nullptr) == (britype == nullptr));
bool isUnsigned = false;
if (blitype) {
if (op == OPERATOR_LSHIFT || op == OPERATOR_RSHIFT)
assert(britype->isUnsigned());
else
assert(blitype->isUnsigned() == britype->isUnsigned());
isUnsigned = blitype->isUnsigned();
}
LIRBuilder builder(context_, llvm::ConstantFolder());
llvm::Value *val = nullptr;
switch (op) {
case OPERATOR_EQEQ:
case OPERATOR_NOTEQ:
case OPERATOR_LT:
case OPERATOR_LE:
case OPERATOR_GT:
case OPERATOR_GE: {
llvm::CmpInst::Predicate pred = compare_op_to_pred(op, ltype, isUnsigned);
if (ltype->isFloatingPointTy())
val = builder.CreateFCmp(pred, leftVal, rightVal, namegen("fcmp"));
else
val = builder.CreateICmp(pred, leftVal, rightVal, namegen("icmp"));
Btype *bcmpt = makeAuxType(llvmBoolType());
// gen compare...
Bexpression *cmpex =
nbuilder_.mkBinaryOp(op, bcmpt, val, left, right, location);
// ... widen to go boolean type
return lateConvert(bool_type(), cmpex, location);
}
case OPERATOR_MINUS: {
if (ltype->isFloatingPointTy())
val = builder.CreateFSub(leftVal, rightVal, namegen("fsub"));
else
val = builder.CreateSub(leftVal, rightVal, namegen("sub"));
break;
}
case OPERATOR_PLUS: {
if (ltype->isFloatingPointTy())
val = builder.CreateFAdd(leftVal, rightVal, namegen("fadd"));
else
val = builder.CreateAdd(leftVal, rightVal, namegen("add"));
break;
}
case OPERATOR_MULT: {
if (ltype->isFloatingPointTy())
val = builder.CreateFMul(leftVal, rightVal, namegen("fmul"));
else
val = builder.CreateMul(leftVal, rightVal, namegen("mul"));
break;
}
case OPERATOR_MOD: {
assert(! ltype->isFloatingPointTy());
if (isUnsigned)
val = builder.CreateURem(leftVal, rightVal, namegen("mod"));
else
val = builder.CreateSRem(leftVal, rightVal, namegen("mod"));
break;
}
case OPERATOR_DIV: {
if (ltype->isFloatingPointTy())
val = builder.CreateFDiv(leftVal, rightVal, namegen("fdiv"));
else if (isUnsigned)
val = builder.CreateUDiv(leftVal, rightVal, namegen("div"));
else
val = builder.CreateSDiv(leftVal, rightVal, namegen("div"));
break;
}
case OPERATOR_OROR:
// Note that the FE will have already expanded out || in a control
// flow context (short circuiting)
// fall through...
case OPERATOR_OR: {
assert(!ltype->isFloatingPointTy());
val = builder.CreateOr(leftVal, rightVal, namegen("ior"));
break;
}
case OPERATOR_BITCLEAR:
// Note that the FE already inserted a complement op to RHS. So
// this is effectively an AND expression.
// fall through...
case OPERATOR_ANDAND:
// Note that the FE will have already expanded out && in a control
// flow context (short circuiting).
// fall through...
case OPERATOR_AND: {
assert(!ltype->isFloatingPointTy());
val = builder.CreateAnd(leftVal, rightVal, namegen("iand"));
break;
}
case OPERATOR_XOR: {
assert(!ltype->isFloatingPointTy() && !rtype->isFloatingPointTy());
val = builder.CreateXor(leftVal, rightVal, namegen("xor"));
break;
}
case OPERATOR_LSHIFT: {
// Note that the FE already inserted conditionals for checking
// large shift amounts. So this can simply lower to a shift
// instruction.
assert(!ltype->isFloatingPointTy() && !rtype->isFloatingPointTy());
val = builder.CreateShl(leftVal, rightVal, namegen("shl"));
break;
}
case OPERATOR_RSHIFT: {
// Note that the FE already inserted conditionals for checking
// large shift amounts. So this can simply lower to a shift
// instruction.
assert(!ltype->isFloatingPointTy() && !rtype->isFloatingPointTy());
if (isUnsigned)
val = builder.CreateLShr(leftVal, rightVal, namegen("shr"));
else
val = builder.CreateAShr(leftVal, rightVal, namegen("shr"));
break;
}
default:
std::cerr << "Op " << op << " unhandled\n";
assert(false);
}
return nbuilder_.mkBinaryOp(op, bltype, val, left, right, location);
}
Bexpression *Llvm_backend::materializeComposite(Bexpression *comExpr)
{
Location location = comExpr->location();
Btype *btype = comExpr->btype();
const std::vector<unsigned long> *indexes = nbuilder_.getIndices(comExpr);
std::vector<Bexpression *> vals =
nbuilder_.extractChildenAndDestroy(comExpr);
llvm::Type *llt = btype->type();
unsigned numElements = 0;
assert(llt->isStructTy() || llt->isArrayTy());
llvm::CompositeType *llct = nullptr;
if (llt->isStructTy()) {
llvm::StructType *llst = llvm::cast<llvm::StructType>(llt);
numElements = llst->getNumElements();
assert(vals.size() == numElements);
llct = llst;
} else {
llvm::ArrayType *llat = llvm::cast<llvm::ArrayType>(llt);
numElements = llat->getNumElements();
llct = llat;
}
// Constant values?
bool isConstant = valuesAreConstant(vals);
if (isConstant)
return makeConstCompositeExpr(btype, llct, numElements,
indexes, vals, location);
else
return makeDelayedCompositeExpr(btype, llct, numElements,
indexes, vals, location);
}
Bexpression *
Llvm_backend::makeDelayedCompositeExpr(Btype *btype,
llvm::CompositeType *llct,
unsigned numElements,
const std::vector<unsigned long> *indexes,
const std::vector<Bexpression *> &vals,
Location location)
{
std::vector<Bexpression *> init_vals(numElements);
if (indexes) {
unsigned long nvals = vals.size();
unsigned long nindxs = indexes->size();
std::set<unsigned long> touched;
for (unsigned ii = 0; ii < nindxs; ++ii) {
auto idx = (*indexes)[ii];
if (numElements != nvals)
touched.insert(idx);
init_vals[idx] = vals[ii];
}
if (numElements != nvals) {
for (unsigned long ii = 0; ii < numElements; ++ii) {
Btype *bElemTyp = elementTypeByIndex(btype, ii);
if (touched.find(ii) == touched.end())
init_vals[ii] = zero_expression(bElemTyp);
}
}
} else {
init_vals = vals;
}
// Here the NULL value signals that we want to delay full instantiation
// of this constant expression until we can identify the storage for it.
llvm::Value *nilval = nullptr;
Binstructions noInstructions;
Bexpression *ccon = nbuilder_.mkComposite(btype, nilval, init_vals,
noInstructions, location);
return ccon;
}
Bexpression *
Llvm_backend::makeConstCompositeExpr(Btype *btype,
llvm::CompositeType *llct,
unsigned numElements,
const std::vector<unsigned long> *indexes,
const std::vector<Bexpression *> &vals,
Location location)
{
llvm::Value *scon;
// If all elements are zero, just create a zero value for the
// aggregate type. No need to create LLVM Value for each element.
bool allZero = true;
for (auto v : vals) {
llvm::Constant *con = llvm::cast<llvm::Constant>(v->value());
if (!con->isNullValue()) {
allZero = false;
break;
}
}
if (allZero)
scon = llvm::ConstantAggregateZero::get(llct);
else {
llvm::SmallVector<llvm::Constant *, 64> llvals(numElements);
unsigned long nvals = vals.size();
if (indexes) {
std::set<unsigned long> touched;
unsigned long nindxs = indexes->size();
for (unsigned ii = 0; ii < nindxs; ++ii) {
auto idx = (*indexes)[ii];
if (numElements != nvals)
touched.insert(idx);
Bexpression *bex = vals[ii];
llvm::Constant *con = llvm::cast<llvm::Constant>(bex->value());
llvm::Type *elt = llct->getTypeAtIndex(ii);
if (elt != con->getType()) {
con = genConvertedConstant(con, elt);
assert(con != nullptr);
}
llvals[idx] = con;
}
if (numElements != nvals) {
for (unsigned long ii = 0; ii < numElements; ++ii) {
if (touched.find(ii) == touched.end()) {
llvm::Type *elt = llct->getTypeAtIndex(ii);
llvals[ii] = llvm::Constant::getNullValue(elt);
}
}
}
} else {
for (unsigned long ii = 0; ii < numElements; ++ii) {
llvm::Constant *con = llvm::cast<llvm::Constant>(vals[ii]->value());
llvm::Type *elt = llct->getTypeAtIndex(ii);
if (elt != con->getType()) {
con = genConvertedConstant(con, elt);
assert(con != nullptr);
}
llvals[ii] = con;
}
}
if (llct->isStructTy()) {
llvm::StructType *llst = llvm::cast<llvm::StructType>(llct);
scon = llvm::ConstantStruct::get(llst, llvals);
} else {
llvm::ArrayType *llat = llvm::cast<llvm::ArrayType>(llct);
scon = llvm::ConstantArray::get(llat, llvals);
}
}
Binstructions noInstructions;
Bexpression *bcon = nbuilder_.mkComposite(btype, scon, vals,
noInstructions, location);
return makeGlobalExpression(bcon, scon, btype, location);
}
Bexpression *Llvm_backend::materializePointerOffset(Bexpression *ptroffExpr)
{
Location location = ptroffExpr->location();
std::vector<Bexpression *> cexprs =
nbuilder_.extractChildenAndDestroy(ptroffExpr);
assert(cexprs.size() == 2);
Bexpression *base = cexprs[0];
Bexpression *index = cexprs[1];
// Resolve index expression
index = resolveVarContext(index);
// When a pointer offset expression appears in a left-hand-side (assignment)
// context, the expected semantics are that location to be written is the
// one pointer to by the result of the pointer offset, meaning that we want
// to propagate any "lvalue-ness" found in 'base' up into the result
// expression (as opposed to delaying a load from 'base' itself).
//
// To achieve this effect, the code below essentially hides away the
// lvalue context on 'base' and then re-establishes it on 'rval' after the
// GEP. This is a painful hack, it would be nice to have a clean way
// to do this.
VarContext vc;
bool setLHS = false;
if (base->varExprPending() && base->varContext().lvalue()) {
setLHS = true;
base->resetVarExprContext();
base->setVarExprPending(false, 0);
}
base = resolveVarContext(base);
// Construct an appropriate GEP
llvm::PointerType *llpt =
llvm::cast<llvm::PointerType>(base->btype()->type());
llvm::Value *gep =
makePointerOffsetGEP(llpt, index->value(), base->value());
// Wrap in a Bexpression
Bexpression *rval = nbuilder_.mkPointerOffset(base->btype(), gep, base,
index, location);
// Re-establish lvalue context (as described above)
if (setLHS)
rval->setVarExprPending(true, 1);
std::string tag(base->tag());
tag += ".ptroff";
rval->setTag(tag);
// We're done
return rval;
}
Bexpression *Llvm_backend::materializeArrayIndex(Bexpression *arindExpr)
{
Location location = arindExpr->location();
std::vector<Bexpression *> cexprs =
nbuilder_.extractChildenAndDestroy(arindExpr);
assert(cexprs.size() == 2);
Bexpression *barray = cexprs[0];
Bexpression *index = cexprs[1];
if (barray->compositeInitPending())
barray = resolveCompositeInit(barray, nullptr);
index = resolveVarContext(index);
// Construct an appropriate GEP
llvm::ArrayType *llat =
llvm::cast<llvm::ArrayType>(barray->btype()->type());
llvm::Value *aval = barray->value();
llvm::Value *ival = index->value();
llvm::Value *eval = nullptr;
bool pending = false;
if (barray->isConstant()) {
if (index->isConstant())
eval = llvm::cast<llvm::Constant>(aval)->getAggregateElement(llvm::cast<llvm::Constant>(ival));
else {
// Constant array with non-constant index. Put the array
// into a temp var and load from there.
llvm::Constant *cval = llvm::cast<llvm::Constant>(aval);
Bvariable *cv = genVarForConstant(cval, barray->btype());
aval = cv->value();
pending = true;
}
}
if (!eval)
eval = makeArrayIndexGEP(llat, ival, aval);
Btype *bet = elementTypeByIndex(barray->btype(), 0);
// Wrap in a Bexpression
Bexpression *rval = nbuilder_.mkArrayIndex(bet, eval, barray, index, location);
if (pending)
rval->setVarExprPending(false, 0);
if (barray->varExprPending())
rval->setVarExprPending(barray->varContext());
std::string tag(barray->tag());
tag += ".index";
rval->setTag(tag);
// We're done
return rval;
}
struct GenCallState {
CABIOracle oracle;
Binstructions instructions;
BinstructionsLIRBuilder builder;
std::vector<Bexpression *> resolvedArgs;
llvm::SmallVector<llvm::Value *, 16> llargs;
llvm::Value *chainVal;
llvm::Value *sretTemp;
BFunctionType *calleeFcnType;
Bfunction *callerFcn;
GenCallState(llvm::LLVMContext &context,
Bfunction *callerFunc,
BFunctionType *calleeFcnTyp,
TypeManager *tm)
: oracle(calleeFcnTyp, tm),
instructions(),
builder(context, &instructions),
chainVal(nullptr),
sretTemp(nullptr),
calleeFcnType(calleeFcnTyp),
callerFcn(callerFunc) { }
};
static bool needSretTemp(const CABIParamInfo &returnInfo,
BFunctionType *calleeFcnTyp)
{
if (returnInfo.disp() == ParmIgnore)
return false;
if (returnInfo.disp() == ParmIndirect)
return true;
if (returnInfo.abiType()->isAggregateType())
return true;
if (calleeFcnTyp->resultType()->type()->isAggregateType())
return true;
return false;
}
void Llvm_backend::genCallProlog(GenCallState &state)
{
const CABIParamInfo &returnInfo = state.oracle.returnInfo();
if (needSretTemp(returnInfo, state.calleeFcnType)) {
assert(state.sretTemp == nullptr);
std::string tname(namegen("sret.actual"));
Btype *resTyp = state.calleeFcnType->resultType();
assert(state.callerFcn);
state.sretTemp = state.callerFcn->createTemporary(resTyp, tname);
if (returnInfo.disp() == ParmIndirect)
state.llargs.push_back(state.sretTemp);
}
// Chain param if needed
const CABIParamInfo &chainInfo = state.oracle.chainInfo();
if (chainInfo.disp() != ParmIgnore) {
assert(chainInfo.disp() == ParmDirect);
llvm::Value *cval = state.chainVal;
if (cval == nullptr)
cval = llvm::UndefValue::get(llvmPtrType());
state.llargs.push_back(cval);
}
}
void
Llvm_backend::genCallMarshallArgs(const std::vector<Bexpression *> &fn_args,
GenCallState &state)
{
for (unsigned idx = 0; idx < fn_args.size(); ++idx) {
const CABIParamInfo &paramInfo = state.oracle.paramInfo(idx);
if (paramInfo.attr() == AttrNest)
continue;
BinstructionsLIRBuilder &builder = state.builder;
// For arguments not passed by value, no call to resolveVarContext
// (we want var address, not var value).
if (paramInfo.disp() == ParmIndirect) {
Bexpression *fnarg = fn_args[idx];
if (fnarg->compositeInitPending())
fnarg = resolveCompositeInit(fnarg, nullptr);
state.resolvedArgs.push_back(fnarg);
llvm::Value *val = fnarg->value();
assert(val);
// spill a constant arg to memory if needed
if (fnarg->isConstant()) {
llvm::Constant *cval = llvm::cast<llvm::Constant>(val);
Bvariable *cv = genVarForConstant(cval, fn_args[idx]->btype());
val = cv->value();
}
llvm::Type *vt = val->getType();
assert(vt->isPointerTy());
if (paramInfo.attr() == AttrByVal && vt->getPointerAddressSpace() != 0) {
// We pass a stack address, which is always in address space 0.
std::string castname(namegen("ascast"));
llvm::Type *pt = llvm::PointerType::get(vt->getPointerElementType(), 0);
val = builder.CreateAddrSpaceCast(val, pt, castname);
}
state.llargs.push_back(val);
continue;
}
// Resolve argument
Varexpr_context ctx = varContextDisp(fn_args[idx]);
if (paramInfo.abiTypes().size() == 2)
ctx = VE_lvalue;
Bexpression *resarg = resolve(fn_args[idx], ctx);
state.resolvedArgs.push_back(resarg);
if (paramInfo.disp() == ParmIgnore)
continue;
// At this point we're passing an argument directly,
// as opposed to in memory.
assert(paramInfo.disp() == ParmDirect);
llvm::Value *val = resarg->value();
if (paramInfo.abiTypes().size() == 1) {
if (ctx == VE_lvalue) {
// Passing single-eightbyte struct or array directly.
if (resarg->isConstant()) {
// If the value we're passing is a composite constant, we have to
// spill it to memory here in order for the casts below to work.
llvm::Constant *cval = llvm::cast<llvm::Constant>(val);
Bvariable *cv = genVarForConstant(cval, resarg->btype());
val = cv->value();
}
std::string castname(namegen("cast"));
// We are going to do a load, so the address space does not matter.
// It seems we may get here with either address space, so we just
// do an address-space-preserving cast.
llvm::Type *ptv =
llvm::PointerType::get(paramInfo.abiType(),
val->getType()->getPointerAddressSpace());
llvm::Value *bitcast = builder.CreateBitCast(val, ptv, castname);
std::string ltag(namegen("ld"));
llvm::Value *ld = builder.CreateLoad(bitcast, ltag);
state.llargs.push_back(ld);
continue;
}
// Passing a single 8-byte-or-less argument.
// Apply any necessary pointer type conversions.
if (val->getType()->isPointerTy() && ctx == VE_rvalue) {
llvm::FunctionType *llft =
llvm::cast<llvm::FunctionType>(state.calleeFcnType->type());
llvm::Type *paramTyp = llft->getParamType(paramInfo.sigOffset());
val = convertForAssignment(resarg, paramTyp);
}
// Apply any necessary sign-extensions or zero-extensions.
if (paramInfo.abiType()->isIntegerTy()) {
if (paramInfo.attr() == AttrZext)
val = builder.CreateZExt(val, paramInfo.abiType(), namegen("zext"));
else if (paramInfo.attr() == AttrSext)
val = builder.CreateZExt(val, paramInfo.abiType(), namegen("sext"));
}
state.llargs.push_back(val);
continue;
}
// This now corresponds to the case of passing the contents of
// a small structure via two pieces / params.
assert(paramInfo.abiTypes().size() == 2);
assert(paramInfo.attr() == AttrNone);
assert(ctx == VE_lvalue);
// Create a struct type of the appropriate shape
llvm::Type *llst = paramInfo.computeABIStructType(typeManager());
llvm::Type *ptst = makeLLVMPointerType(llst);
// If the value we're passing is a composite constant, we have to
// spill it to memory here in order for the casts below to work.
// Note that the spill is not needed if the value corresponds to a
// delated load of a composite variable (in which case it will
// already be an address). For example, if resarg corresponds to
// an anonymous constant value like [2]float64{10.0,10.0} then we
// need to spill, whereas if we're dealing with a reference to a
// named global constant, there is no need to spill.
if (resarg->isConstant() && val->getType() == resarg->btype()->type()) {
llvm::Constant *cval = llvm::cast<llvm::Constant>(val);
Bvariable *cv = genVarForConstant(cval, resarg->btype());
val = cv->value();
}
// Cast the value to the struct type
std::string tag(namegen("cast"));
llvm::Value *bitcast =
builder.CreatePointerBitCastOrAddrSpaceCast(val, ptst, tag);
// Load up each field
std::string ftag0(namegen("field0"));
llvm::Value *field0gep =
builder.CreateConstInBoundsGEP2_32(llst, bitcast, 0, 0, ftag0);
std::string ltag0(namegen("ld"));
llvm::Value *ld0 = builder.CreateLoad(field0gep, ltag0);
state.llargs.push_back(ld0);
std::string ftag1(namegen("field1"));
llvm::Value *field1gep =
builder.CreateConstInBoundsGEP2_32(llst, bitcast, 0, 1, ftag1);
std::string ltag1(namegen("ld"));
llvm::Value *ld1 = builder.CreateLoad(field1gep, ltag1);
state.llargs.push_back(ld1);
}
}
void Llvm_backend::genCallAttributes(GenCallState &state, llvm::CallInst *call)
{
// Sret attribute if needed
const CABIParamInfo &returnInfo = state.oracle.returnInfo();
if (returnInfo.disp() == ParmIndirect) {
call->addAttribute(1, llvm::Attribute::StructRet);
call->addAttribute(1, llvm::Attribute::get(call->getContext(), "go_sret"));
}
// Nest attribute if needed
const CABIParamInfo &chainInfo = state.oracle.chainInfo();
if (chainInfo.disp() != ParmIgnore)
call->addAttribute(chainInfo.sigOffset()+1, llvm::Attribute::Nest);
// Remainder of param attributes
const std::vector<Btype *> &paramTypes = state.calleeFcnType->paramTypes();
for (unsigned idx = 0; idx < paramTypes.size(); ++idx) {
const CABIParamInfo &paramInfo = state.oracle.paramInfo(idx);
if (paramInfo.disp() == ParmIgnore)
continue;
assert(paramInfo.attr() != AttrNest);
assert(paramInfo.attr() != AttrStructReturn);
unsigned off = paramInfo.sigOffset() + 1;
if (paramInfo.attr() == AttrByVal)
call->addAttribute(off, llvm::Attribute::ByVal);
else if (paramInfo.attr() == AttrZext)
call->addAttribute(off, llvm::Attribute::ZExt);
else if (paramInfo.attr() == AttrSext)
call->addAttribute(off, llvm::Attribute::SExt);
}
}
void Llvm_backend::genCallEpilog(GenCallState &state,
llvm::Instruction *callInst,
Bexpression *callExpr)
{
const CABIParamInfo &returnInfo = state.oracle.returnInfo();
if (needSretTemp(returnInfo, state.calleeFcnType)) {
assert(state.sretTemp);
assert(callExpr->value() == state.sretTemp);
callExpr->setVarExprPending(VE_rvalue, 0);
if (returnInfo.disp() == ParmDirect) {
// The call is returning something by value that doesn't match
// the expected abstract result type of the function. Cast the
// sret storage location to a pointer to the abi type and store
// the ABI return value into it.
BinstructionsLIRBuilder builder(context_, callExpr);
llvm::Type *rt = (returnInfo.abiTypes().size() == 1 ?
returnInfo.abiType() :
returnInfo.computeABIStructType(typeManager()));
llvm::Type *ptrt = llvm::PointerType::get(rt, 0);
std::string castname(namegen("cast"));
llvm::Value *bitcast = builder.CreateBitCast(state.sretTemp,
ptrt, castname);
std::string stname(namegen("st"));
builder.CreateStore(callInst, bitcast);
}
}
}
Bexpression *Llvm_backend::materializeCall(Bexpression *callExpr)
{
Location location = callExpr->location();
Bfunction *caller = callExpr->getFunction();
std::vector<Bexpression *> cexprs =
nbuilder_.extractChildenAndDestroy(callExpr);
Bexpression *fn_expr = cexprs[0];
Bexpression *chain_expr = cexprs[1];
std::vector<Bexpression *> fn_args;
for (unsigned idx = 2; idx < cexprs.size(); ++idx) {
fn_args.push_back(cexprs[idx]);
}
// Resolve fcn. Expect pointer-to-function type here.
fn_expr = resolveVarContext(fn_expr);
assert(fn_expr->btype()->type()->isPointerTy());
BFunctionType *calleeFcnTyp = unpackFunctionType(fn_expr->btype());
Btype *rbtype = calleeFcnTyp->resultType();
llvm::Value *fnval = fn_expr->value();
// Some intrinsic functions need additional args. Add them.
// TODO: currently this is specific to llvm.cttz, llvm.memmove, and
// llvm.memcpy; if the list expands too much more it might make
// sense to incorporate a description of the extra args into the
// builtin table entry.
if (llvm::isa<llvm::Function>(fnval)) {
llvm::Function *fcn = llvm::cast<llvm::Function>(fnval);
switch (fcn->getIntrinsicID()) {
case llvm::Intrinsic::cttz: {
// @llvm.cttz.i32 (i32 <src>, i1 <is_zero_undef>)
// Add the <is_zero_undef> arg.
// GCC's __builtin_ctz results undefined for 0 input.
llvm::Value *con = llvm::ConstantInt::getTrue(context_);
Btype *bt = makeAuxType(llvmBoolType());
Bexpression *conexpr = nbuilder_.mkConst(bt, con);
fn_args.push_back(conexpr);
break;
}
case llvm::Intrinsic::memmove:
case llvm::Intrinsic::memcpy: {
// memmove/memcpy take additional volatile arg
// volatile => false
llvm::Value *fcon = llvm::ConstantInt::getFalse(context_);
Btype *bt = makeAuxType(llvmBoolType());
Bexpression *volexpr = nbuilder_.mkConst(bt, fcon);
fn_args.push_back(volexpr);
break;
}
case llvm::Intrinsic::prefetch: {
// prefetch takes an additional arg for cache type
// (0: instruction, 1: data).
Btype *buint32t = integerType(true, 32);
llvm::Constant *c1 = llvm::ConstantInt::get(llvmInt32Type(), 1);
Bexpression *conexpr = nbuilder_.mkConst(buint32t, c1);
fn_args.push_back(conexpr);
break;
}
case llvm::Intrinsic::eh_dwarf_cfa: {
// llvm.eh.dwarf.cfa takes an additional arg 0.
Btype *buint32t = integerType(true, 32);
llvm::Constant *c1 = llvm::ConstantInt::get(llvmInt32Type(), 0);
Bexpression *conexpr = nbuilder_.mkConst(buint32t, c1);
fn_args.push_back(conexpr);
break;
}
default: {
// at the moment no other instrinsics need special handling
}
}
}
// State object to help with marshalling of call arguments, etc.
GenCallState state(context_, caller, calleeFcnTyp, typeManager());
// Static chain expression if applicable
if (chain_expr->btype() != void_type()) {
chain_expr = resolveVarContext(chain_expr);
assert(chain_expr->btype()->type()->isPointerTy());
Btype *bpt = makeAuxType(llvmPtrType());
chain_expr = lateConvert(bpt, chain_expr, location);
assert(chain_expr->value() != nullptr);
state.chainVal = chain_expr->value();
}
// Set up for call (including creation of return tmp if needed)
genCallProlog(state);
// Unpack / resolve / marshall arguments
genCallMarshallArgs(fn_args, state);
// Create the actual call instruction
llvm::CallInst *call = nullptr;
llvm::Value *callValue = nullptr;
if (llvm::isa<llvm::Function>(fnval)) {
llvm::Function *fcn = llvm::cast<llvm::Function>(fnval);
BuiltinEntry *be = builtinTable_->lookup(fcn->getName());
if (be) {
BuiltinExprMaker makerfn = be->exprMaker();
if (makerfn)
callValue = makerfn(state.llargs, &state.builder, this);
}
}
if (!callValue) {
llvm::FunctionType *llft =
llvm::cast<llvm::FunctionType>(calleeFcnTyp->type());
bool isvoid = llft->getReturnType()->isVoidTy();
std::string callname(isvoid ? "" : namegen("call"));
call = state.builder.CreateCall(llft, fnval,
state.llargs, callname);
genCallAttributes(state, call);
callValue = (state.sretTemp ? state.sretTemp : call);
}
Bexpression *rval =
nbuilder_.mkCall(rbtype, callValue, caller, fn_expr, chain_expr,
state.resolvedArgs, state.instructions, location);
state.instructions.clear();
if (call)
genCallEpilog(state, call, rval);
return rval;
}
llvm::Value *
Llvm_backend::convertForAssignment(Bexpression *src,
llvm::Type *dstToType)
{
if (src->value()->getType() == dstToType)
return src->value();
llvm::Function *dummyFcn = errorFunction_->function();
BlockLIRBuilder builder(dummyFcn, this);
llvm::Value *val = convertForAssignment(src->btype(), src->value(),
dstToType, &builder);
src->appendInstructions(builder.instructions());
return val;
}
llvm::Value *
Llvm_backend::convertForAssignment(Btype *srcBType,
llvm::Value *srcVal,
llvm::Type *dstToType,
BlockLIRBuilder *builder)
{
llvm::Type *srcType = srcVal->getType();
if (dstToType == srcType)
return srcVal;
// Case 1: handle discrepancies between representations of function
// descriptors. All front end function descriptor types are structs
// with a single field, however this field can sometimes be a pointer
// to function, and sometimes it can be of uintptr type.
bool srcPtrToFD = isPtrToFuncDescriptorType(srcType);
bool dstPtrToFD = isPtrToFuncDescriptorType(dstToType);
if (srcPtrToFD && dstPtrToFD) {
std::string tag(namegen("cast"));
llvm::Value *bitcast = builder->CreateBitCast(srcVal, dstToType, tag);
return bitcast;
}
// Case 2: handle circular function types.
bool dstCircFunc = isCircularFunctionType(dstToType);
bool srcCircFunc = isCircularFunctionType(srcType);
bool srcFuncPtr = isPtrToFuncType(srcType);
if (((srcPtrToFD || srcFuncPtr || srcCircFunc) && dstCircFunc) ||
(srcCircFunc && dstPtrToFD)) {
std::string tag(namegen("cast"));
llvm::Value *bitcast = builder->CreateBitCast(srcVal, dstToType, tag);
return bitcast;
}
// Case 3: handle raw function pointer assignment (frontend will
// sometimes take a function pointer and assign it to "void *" without
// an explicit conversion).
bool dstPtrToVoid = isPtrToVoidType(dstToType);
if (dstPtrToVoid && srcFuncPtr) {
std::string tag(namegen("cast"));
llvm::Value *bitcast = builder->CreateBitCast(srcVal, dstToType, tag);
return bitcast;
}
// Case 4: in some cases when calling a function (for example, __gogo)
// the front end will pass a raw function vale in place of a function
// descriptor. Allow this case.
if (dstPtrToFD && srcFuncPtr) {
std::string tag(namegen("cast"));
llvm::Value *bitcast =
builder->CreatePointerBitCastOrAddrSpaceCast(srcVal, dstToType, tag);
return bitcast;
}
// Case 5: handle polymorphic nil pointer expressions-- these are
// generated without a type initially, so we need to convert them
// to the appropriate type if they appear in an assignment context.
if (srcVal == nil_pointer_expression()->value()) {
std::string tag(namegen("cast"));
llvm::Value *bitcast = builder->CreateBitCast(srcVal, dstToType, tag);
return bitcast;
}
// Case 6: the code that creates interface values stores pointers of
// various flavors into i8*. Ideally it would be better to insert
// forced type conversions in the FE, but for now we allow this case.
bool srcPtrToIface = isPtrToIfaceStructType(srcType);
if (dstPtrToVoid && srcPtrToIface) {
std::string tag(namegen("cast"));
llvm::Value *bitcast = builder->CreateBitCast(srcVal, dstToType, tag);
return bitcast;
}
// Case 7: when creating slice values it's common for the frontend
// to mix pointers and arrays, e.g. assign "[3 x i64]*" to "i64**".
// Allow this sort of conversion.
llvm::Type *elt =
(dstToType->isPointerTy() ?
llvm::cast<llvm::PointerType>(dstToType)->getElementType() : nullptr);
if (elt && isPtrToArrayOf(srcType, elt)) {
std::string tag(namegen("cast"));
llvm::Value *bitcast = builder->CreateBitCast(srcVal, dstToType, tag);
return bitcast;
}
// Case 8: also when creating slice values it's common for the
// frontend to assign pointer-to-X to unsafe.Pointer (and vice versa)
// without an explicit cast. Allow this for now.
if ((dstToType == llvmPtrType() && llvm::isa<llvm::PointerType>(srcType)) ||
(srcType == llvmPtrType() && llvm::isa<llvm::PointerType>(dstToType))) {
std::string tag(namegen("cast"));
llvm::Value *bitcast = builder->CreatePointerBitCastOrAddrSpaceCast(srcVal, dstToType, tag);
return bitcast;
}
// Case 9: related to case 1 above, interface value expressions can
// contain C function pointers stored as "void *" instead of
// concrete pointer-to-function values. For example, consider a
// value V1 of the form
//
// { { T1*, void* }, O* }
//
// where T1 is a type descriptor and O is an object; this value can
// sometimes be assigned to a location of type
//
// { { T1*, F* }, O* }
//
// where F is a concrete C pointer-to-function (as opposed to "void*").
// Allow conversions of this sort for now.
std::set<llvm::Type *> visited;
if (fcnPointerCompatible(dstToType, srcType, visited)) {
std::string tag(namegen("cast"));
llvm::Value *bitcast =
builder->CreatePointerBitCastOrAddrSpaceCast(srcVal, dstToType, tag);
return bitcast;
}
// Case 10: circular pointer type (ex: type T *T; var p T; p = &p)
BPointerType *srcbpt = srcBType->castToBPointerType();
if (srcbpt) {
Btype *ctypconv = circularTypeAddrConversion(srcbpt->toType());
if (ctypconv != nullptr && ctypconv->type() == dstToType) {
std::string tag(namegen("cast"));
llvm::Value *bitcast = builder->CreateBitCast(srcVal, dstToType, tag);
return bitcast;
}
}
return srcVal;
}
// Walk the specified expression and invoke setVarExprPending on
// each var expression, with correct lvalue/rvalue tag depending on
// context.
class VarContextVisitor {
public:
VarContextVisitor(Bexpression *top,
Varexpr_context lvalueContext,
bool dumpDiffs)
: dumpDiffs_(dumpDiffs)
{
if (lvalueContext == VE_lvalue && isMem(top))
setLvalue(top);
}
std::pair< std::pair<VisitDisp, VisitChildDisp>, Bnode *>
visitChildPre(Bnode *parent, Bnode *child) {
Bexpression *eparent = parent->castToBexpression();
assert(eparent != nullptr);
// Don't descend into stmts or non-var nodes with values.
Bexpression *echild = child->castToBexpression();
if (child->isStmt() || (echild->value() != nullptr &&
echild->flavor() != N_Var))
return std::make_pair(std::make_pair(ContinueWalk, SkipChild), child);
// Propagate lvalue property down from parent to child through a memory
// operation such as a fieldref or arrayindex if applicable. For example,
// for the tree build from go code "x.f1[y]" such as
//
// array_index
// / \.
// field var(y)
// /
// var(x)
//
// If the top node (array_index) is in a left-hand-side position,
// then we want to flag "field" and "var(x)" nodes as being in an
// LHS context also, but not the "var(y)" node (it is not being
// assigned).
assert(echild != nullptr);
if (isLvalue(eparent) && isMem(echild)) {
Bexpression *cmem = memArg(eparent);
if (cmem == echild)
setLvalue(echild);
}
return std::make_pair(std::make_pair(ContinueWalk, VisitChild), child);
}
// Apply "var pending" tags to var exprs bottom up, once downward propagation
// of lvalue context is complete.
std::pair<VisitDisp, Bnode *> visitNodePost(Bnode *node)
{
Bexpression *expr = node->castToBexpression();
if (expr == nullptr || (expr->value() && expr->flavor() != N_Var))
return std::make_pair(ContinueWalk, expr);
if (expr->flavor() == N_Var)
setVarExprPending(expr, isLvalue(expr), 0);
// Debugging only. This is intended to provide a way to compare the
// tags applied by the frontend vs the tags this visitor generates.
if (dumpDiffs_)
dumpDiff(expr);
auto it = varcontext_.find(expr);
if (it != varcontext_.end()) {
VarContext vc(it->second);
bool lvalue = vc.lvalue();
if (expr->varExprPending()) {
assert(vc.equal(expr->varContext()));
} else {
expr->setVarExprPending(lvalue, 0);
}
}
return std::make_pair(ContinueWalk, expr);
}
// boilerplate
std::pair<VisitDisp, Bnode *> visitNodePre(Bnode *node) {
return std::make_pair(ContinueWalk, node);
}
// boilerplate
std::pair<VisitDisp, Bnode *> visitChildPost(Bnode *parent, Bnode *child) {
return std::make_pair(ContinueWalk, child);
}
private:
// Debugging only.
void dumpDiff(Bexpression *expr)
{
if (expr->value() && expr->flavor() != N_Var)
return;
VarContext oldvc;
if (expr->varExprPending())
oldvc = expr->varContext();
VarContext newvc;
auto nit = varcontext_.find(expr);
if (nit != varcontext_.end())
newvc = nit->second;
if (newvc.equal(oldvc))
return;
std::cerr << "Expr " << expr->id()
<< " " << expr->flavstr() << " ";
if (oldvc.pending()) {
std::cerr << "old VC(" << (oldvc.pending() ? "true" : "false")
<< "," << (oldvc.lvalue() ? "lval" : "rval")
<< "," << oldvc.addrLevel() << ") ";
}
if (newvc.pending()) {
std::cerr << "new VC(" << (newvc.pending() ? "true" : "false")
<< "," << (newvc.lvalue() ? "lval" : "rval")
<< "," << newvc.addrLevel() << ") ";
}
std::cerr << "\n";
expr->dump();
std::cerr << "\n";
}
Bexpression *memArg(Bexpression *expr) {
const std::vector<Bnode *> &kids = expr->children();
switch(expr->flavor()) {
case N_StructField:
case N_ArrayIndex:
case N_Address:
case N_Conversion:
case N_PointerOffset:
return kids[0]->castToBexpression();
default:
return nullptr;
}
}
bool isMem(Bexpression *expr) {
switch(expr->flavor()) {
case N_Var:
case N_StructField:
case N_Address:
case N_Deref:
case N_Conversion:
case N_ArrayIndex:
case N_PointerOffset:
return true;
default:
return false;
}
}
void setLvalue(Bexpression *expr) {
assert(lvalue_.find(expr) == lvalue_.end());
lvalue_.insert(expr);
}
bool isLvalue(Bexpression *expr) {
return lvalue_.find(expr) != lvalue_.end();
}
void setVarExprPending(Bexpression *expr, bool lvalue, unsigned addrLevel) {
assert(expr);
VarContext vc(lvalue, addrLevel);
varcontext_[expr] = vc;
}
private:
std::set<Bnode *> lvalue_;
std::map<Bexpression *, VarContext> varcontext_;
bool dumpDiffs_;
};
// Helper visitor class for expression folding; removes redundant
// nodes in preparation for materialization.
class FoldVisitor {
public:
FoldVisitor(Llvm_backend *be) : be_(be) { }
std::pair<VisitDisp, Bnode *> visitNodePost(Bnode *node) {
Bexpression *expr = node->castToBexpression();
if (!expr)
return std::make_pair(ContinueWalk, node);
if (expr && expr->value())
return std::make_pair(ContinueWalk, node);
// Fold addr(deref(X)) => X
if (node->flavor() == N_Address) {
std::vector<Bexpression *> akids = expr->getChildExprs();
if (akids[0]->flavor() == N_Deref) {
Bexpression *deref = akids[0];
// Extract children and delete first the addr node, then the
// deref node. Order is important; if we delete the deref first
// then the integrity visitor will wind up trying to access the
// deleted deref.
be_->nodeBuilder().extractChildenAndDestroy(expr);
std::vector<Bexpression *> dkids =
be_->nodeBuilder().extractChildenAndDestroy(deref);
// Return result
expr = dkids[0];
}
}
return std::make_pair(ContinueWalk, expr);
}
// If child is a statement (ex: compound expr) or if child
// already has an LLVM value, then prune walk at this node.
std::pair< std::pair<VisitDisp, VisitChildDisp>, Bnode *>
visitChildPre(Bnode *parent, Bnode *child) {
Bexpression *echild = child->castToBexpression();
if (child->isStmt() || echild->value() != nullptr)
return std::make_pair(std::make_pair(ContinueWalk, SkipChild), child);
return std::make_pair(std::make_pair(ContinueWalk, VisitChild), child);
}
// Boilerplate
std::pair<VisitDisp, Bnode *> visitNodePre(Bnode *node) {
return std::make_pair(ContinueWalk, node);
}
std::pair<VisitDisp, Bnode *> visitChildPost(Bnode *parent, Bnode *child) {
return std::make_pair(ContinueWalk, child);
}
private:
Llvm_backend *be_;
};
class MaterializeVisitor {
public:
MaterializeVisitor(Llvm_backend *be,
Bexpression *topNode,
Varexpr_context ctx)
: be_(be), topNode_(topNode), ctx_(ctx) { }
std::pair<VisitDisp, Bnode *> visitNodePre(Bnode *node) {
return std::make_pair(ContinueWalk, node);
}
std::pair<VisitDisp, Bnode *> visitNodePost(Bnode *node) {
Bexpression *expr = node->castToBexpression();
if (expr && expr->value())
return std::make_pair(ContinueWalk, node);
switch(node->flavor()) {
case N_EmptyStmt:
case N_LabelStmt:
case N_GotoStmt:
case N_ExprStmt:
case N_ReturnStmt:
case N_DeferStmt:
case N_IfStmt:
case N_ExcepStmt:
case N_BlockStmt:
case N_SwitchStmt: {
return std::make_pair(ContinueWalk, node);
}
case N_Error:
case N_Const:
case N_Var:
case N_FcnAddress:
case N_LabelAddress: {
break;
}
case N_Conversion: {
expr = be_->materializeConversion(expr);
break;
}
case N_Deref: {
bool isLHS = (expr == topNode_ && ctx_ == VE_lvalue);
expr = be_->materializeIndirect(expr, isLHS);
break;
}
case N_Address: {
expr = be_->materializeAddress(expr);
break;
}
case N_UnaryOp: {
expr = be_->materializeUnary(expr);
break;
}
case N_StructField: {
expr = be_->materializeStructField(expr);
break;
}
case N_BinaryOp: {
expr = be_->materializeBinary(expr);
break;
}
case N_Compound: {
expr = be_->materializeCompound(expr);
break;
}
case N_ArrayIndex: {
expr = be_->materializeArrayIndex(expr);
break;
}
case N_PointerOffset: {
expr = be_->materializePointerOffset(expr);
break;
}
case N_Composite: {
expr = be_->materializeComposite(expr);
break;
}
case N_Call: {
expr = be_->materializeCall(expr);
break;
}
case N_Conditional: {
expr = be_->materializeConditional(expr);
break;
}
}
assert(expr->value() != nullptr ||
expr->flavor() == N_Composite ||
expr->btype() == be_->void_type());
return std::make_pair(ContinueWalk, expr);
}
// If child is a statement (ex: compound expr), then no need to
// visit subtree (should already be materialized). Similarly if
// child already has an LLVM value, then prune walk at this node
std::pair< std::pair<VisitDisp, VisitChildDisp>, Bnode *>
visitChildPre(Bnode *parent, Bnode *child) {
Bexpression *echild = child->castToBexpression();
if (child->isStmt() || echild->value() != nullptr)
return std::make_pair(std::make_pair(ContinueWalk, SkipChild), child);
return std::make_pair(std::make_pair(ContinueWalk, VisitChild), child);
}
std::pair<VisitDisp, Bnode *> visitChildPost(Bnode *parent, Bnode *child) {
return std::make_pair(ContinueWalk, child);
}
private:
Llvm_backend *be_;
Bexpression *topNode_;
Varexpr_context ctx_;
};
Bexpression *Llvm_backend::materialize(Bexpression *expr,
Varexpr_context lvalueContext)
{
// Repair any node sharing at this point-- the materializer
// assumes that any node it visits can be destroyed/replaced
// without impacting some other portion of the tree.
enforceTreeIntegrity(expr);
// TODO:
// - don't really need a treewalk in the non-LHS case to apply
// can context tags; it would be simpler to only do the walk
// in the LHS case (and just apply var context tags when
// var expression is initially created)
// - an extension of the above: pass in the LHS/RHS context
// and propagate recursively during the materialize() walk,
// instead of having a separate tree-walk here.
// Locate and tag var expressions within the tree, selecting LHS or
// RHS context as appropriate. Needs to be done after the call above
// so as to insure that there are no share var expressions.
VarContextVisitor vcvis(expr, lvalueContext, false);
update_walk_nodes(expr, vcvis);
// Perform some basic folding operations. This is easier to do
// here so as not to worry about sharing.
FoldVisitor fvis(this);
Bnode *folded = update_walk_nodes(expr, fvis);
expr = folded->castToBexpression();
// Walk to materialize llvm values.
MaterializeVisitor mvis(this, expr, lvalueContext);
Bnode *materialized = update_walk_nodes(expr, mvis);
return materialized->castToBexpression();
}
Bexpression *Llvm_backend::lateConvert(Btype *type,
Bexpression *expr,
Location loc)
{
return materialize(convert_expression(type, expr, loc));
}