compiler: generate memmove for non-pointer slice copy
The builtin copy function is lowered to runtime functions
slicecopy, stringslicecopy, or typedslicecopy. The first two are
basically thin wrappers of memmove. Instead of making a runtime
call, we can just use __builtin_memmove. This gives the compiler
backend opportunities for further optimizations.
Move the lowering of builtin copy function to flatten phase for
the ease of rewriting.
Also do this optimization for the copy part of append(s1, s2...).
Change-Id: I1adff34dac9dd0680b67849f7169a3593b9e1ea8
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/170005
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/go/expressions.cc b/go/expressions.cc
index 402e8d3..707636a 100644
--- a/go/expressions.cc
+++ b/go/expressions.cc
@@ -7743,8 +7743,9 @@
return this;
}
-// Flatten a builtin call expression. This turns the arguments of copy and
-// append into temporary expressions.
+// Flatten a builtin call expression. This turns the arguments of some
+// builtin calls into temporary expressions. Also expand copy and append
+// to runtime calls.
Expression*
Builtin_call_expression::do_flatten(Gogo* gogo, Named_object* function,
@@ -7781,6 +7782,85 @@
*pa = Expression::make_temporary_reference(temp, loc);
}
}
+
+ // Lower to runtime call.
+ const Expression_list* args = this->args();
+ go_assert(args != NULL && args->size() == 2);
+ Expression* arg1 = args->front();
+ Expression* arg2 = args->back();
+ go_assert(arg1->is_variable());
+ go_assert(arg2->is_variable());
+ bool arg2_is_string = arg2->type()->is_string_type();
+
+ Expression* ret;
+ Type* et = at->array_type()->element_type();
+ if (et->has_pointer())
+ {
+ Expression* td = Expression::make_type_descriptor(et, loc);
+ ret = Runtime::make_call(Runtime::TYPEDSLICECOPY, loc,
+ 3, td, arg1, arg2);
+ }
+ else
+ {
+ Type* int_type = Type::lookup_integer_type("int");
+ Type* uintptr_type = Type::lookup_integer_type("uintptr");
+
+ // l1 = len(arg1)
+ Named_object* lenfn = gogo->lookup_global("len");
+ Expression* lenref = Expression::make_func_reference(lenfn, NULL, loc);
+ Expression_list* len_args = new Expression_list();
+ len_args->push_back(arg1->copy());
+ Expression* len1 = Expression::make_call(lenref, len_args, false, loc);
+ gogo->lower_expression(function, inserter, &len1);
+ gogo->flatten_expression(function, inserter, &len1);
+ Temporary_statement* l1tmp = Statement::make_temporary(int_type, len1, loc);
+ inserter->insert(l1tmp);
+
+ // l2 = len(arg2)
+ len_args = new Expression_list();
+ len_args->push_back(arg2->copy());
+ Expression* len2 = Expression::make_call(lenref, len_args, false, loc);
+ gogo->lower_expression(function, inserter, &len2);
+ gogo->flatten_expression(function, inserter, &len2);
+ Temporary_statement* l2tmp = Statement::make_temporary(int_type, len2, loc);
+ inserter->insert(l2tmp);
+
+ // n = (l1 < l2 ? l1 : l2)
+ Expression* l1ref = Expression::make_temporary_reference(l1tmp, loc);
+ Expression* l2ref = Expression::make_temporary_reference(l2tmp, loc);
+ Expression* cond = Expression::make_binary(OPERATOR_LT, l1ref, l2ref, loc);
+ Expression* n = Expression::make_conditional(cond,
+ l1ref->copy(),
+ l2ref->copy(),
+ loc);
+ Temporary_statement* ntmp = Statement::make_temporary(NULL, n, loc);
+ inserter->insert(ntmp);
+
+ // sz = n * sizeof(elem_type)
+ Expression* nref = Expression::make_temporary_reference(ntmp, loc);
+ nref = Expression::make_cast(uintptr_type, nref, loc);
+ Expression* sz = Expression::make_type_info(et, TYPE_INFO_SIZE);
+ sz = Expression::make_binary(OPERATOR_MULT, sz, nref, loc);
+
+ // memmove(arg1.ptr, arg2.ptr, sz)
+ Expression* p1 = Expression::make_slice_info(arg1,
+ SLICE_INFO_VALUE_POINTER,
+ loc);
+ Expression* p2 = (arg2_is_string
+ ? Expression::make_string_info(arg2,
+ STRING_INFO_DATA,
+ loc)
+ : Expression::make_slice_info(arg2,
+ SLICE_INFO_VALUE_POINTER,
+ loc));
+ Expression* call = Runtime::make_call(Runtime::BUILTIN_MEMMOVE, loc, 3,
+ p1, p2, sz);
+
+ // n is the return value of copy
+ nref = Expression::make_temporary_reference(ntmp, loc);
+ ret = Expression::make_compound(call, nref, loc);
+ }
+ return ret;
}
break;
@@ -8209,21 +8289,51 @@
if (this->is_varargs())
{
- // copy(s1tmp[l1tmp:], s2tmp)
- a1 = Expression::make_temporary_reference(s1tmp, loc);
- ref = Expression::make_temporary_reference(l1tmp, loc);
- Expression* nil = Expression::make_nil(loc);
- a1 = Expression::make_array_index(a1, ref, nil, NULL, loc);
- a1->array_index_expression()->set_needs_bounds_check(false);
+ if (element_type->has_pointer())
+ {
+ // copy(s1tmp[l1tmp:], s2tmp)
+ a1 = Expression::make_temporary_reference(s1tmp, loc);
+ ref = Expression::make_temporary_reference(l1tmp, loc);
+ Expression* nil = Expression::make_nil(loc);
+ a1 = Expression::make_array_index(a1, ref, nil, NULL, loc);
+ a1->array_index_expression()->set_needs_bounds_check(false);
- a2 = Expression::make_temporary_reference(s2tmp, loc);
+ a2 = Expression::make_temporary_reference(s2tmp, loc);
- Named_object* copyfn = gogo->lookup_global("copy");
- Expression* copyref = Expression::make_func_reference(copyfn, NULL, loc);
- call_args = new Expression_list();
- call_args->push_back(a1);
- call_args->push_back(a2);
- call = Expression::make_call(copyref, call_args, false, loc);
+ Named_object* copyfn = gogo->lookup_global("copy");
+ Expression* copyref = Expression::make_func_reference(copyfn, NULL, loc);
+ call_args = new Expression_list();
+ call_args->push_back(a1);
+ call_args->push_back(a2);
+ call = Expression::make_call(copyref, call_args, false, loc);
+ }
+ else
+ {
+ // memmove(&s1tmp[l1tmp], s2tmp.ptr, l2tmp*sizeof(elem))
+ a1 = Expression::make_temporary_reference(s1tmp, loc);
+ ref = Expression::make_temporary_reference(l1tmp, loc);
+ a1 = Expression::make_array_index(a1, ref, NULL, NULL, loc);
+ a1->array_index_expression()->set_needs_bounds_check(false);
+ a1 = Expression::make_unary(OPERATOR_AND, a1, loc);
+
+ a2 = Expression::make_temporary_reference(s2tmp, loc);
+ a2 = (a2->type()->is_string_type()
+ ? Expression::make_string_info(a2,
+ STRING_INFO_DATA,
+ loc)
+ : Expression::make_slice_info(a2,
+ SLICE_INFO_VALUE_POINTER,
+ loc));
+
+ Type* uintptr_type = Type::lookup_integer_type("uintptr");
+ ref = Expression::make_temporary_reference(l2tmp, loc);
+ ref = Expression::make_cast(uintptr_type, ref, loc);
+ a3 = Expression::make_type_info(element_type, TYPE_INFO_SIZE);
+ a3 = Expression::make_binary(OPERATOR_MULT, a3, ref, loc);
+
+ call = Runtime::make_call(Runtime::BUILTIN_MEMMOVE, loc, 3,
+ a1, a2, a3);
+ }
gogo->lower_expression(function, inserter, &call);
gogo->flatten_expression(function, inserter, &call);
inserter->insert(Statement::make_statement(call, false));
@@ -9666,44 +9776,8 @@
}
case BUILTIN_COPY:
- {
- const Expression_list* args = this->args();
- go_assert(args != NULL && args->size() == 2);
- Expression* arg1 = args->front();
- Expression* arg2 = args->back();
-
- Type* arg1_type = arg1->type();
- Array_type* at = arg1_type->array_type();
- go_assert(arg1->is_variable());
-
- Expression* call;
-
- Type* arg2_type = arg2->type();
- go_assert(arg2->is_variable());
- if (arg2_type->is_string_type())
- call = Runtime::make_call(Runtime::SLICESTRINGCOPY, location,
- 2, arg1, arg2);
- else
- {
- Type* et = at->element_type();
- if (et->has_pointer())
- {
- Expression* td = Expression::make_type_descriptor(et,
- location);
- call = Runtime::make_call(Runtime::TYPEDSLICECOPY, location,
- 3, td, arg1, arg2);
- }
- else
- {
- Expression* sz = Expression::make_type_info(et,
- TYPE_INFO_SIZE);
- call = Runtime::make_call(Runtime::SLICECOPY, location, 3,
- arg1, arg2, sz);
- }
- }
-
- return call->get_backend(context);
- }
+ // Handled in Builtin_call_expression::do_flatten.
+ go_unreachable();
case BUILTIN_APPEND:
// Handled in Builtin_call_expression::flatten_append.
diff --git a/go/runtime.def b/go/runtime.def
index 0fcc0a8..c17b481 100644
--- a/go/runtime.def
+++ b/go/runtime.def
@@ -372,6 +372,10 @@
// Unreachable code.
DEF_GO_RUNTIME(UNREACHABLE, "__builtin_unreachable", P0(), R0())
+// Memmove.
+DEF_GO_RUNTIME(BUILTIN_MEMMOVE, "__builtin_memmove",
+ P3(POINTER, POINTER, UINTPTR), R0())
+
// Remove helper macros.
#undef ABFT6
#undef ABFT2
