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compiler: in composite literals use temps only for interfaces

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For a composite literal we only need to introduce a temporary variable
if we may be converting to an interface type, so only do it then.
This saves over 80% of compilation time when using gccgo to compile
cmd/internal/obj/x86, as the GCC middle-end spends a lot of time
pointlessly computing interactions between temporary variables.

For PR debug/101064
For golang/go#46600

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/331513
This commit is contained in:
Ian Lance Taylor 2021-06-29 11:00:13 -07:00
parent 2cf8d3fc05
commit 528ed79401
1 changed files with 13 additions and 4 deletions
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17
gcc/go/gofrontend/expressions.cc
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@ -15141,7 +15141,7 @@ Struct_construction_expression::do_copy()
}
// Flatten a struct construction expression. Store the values into
// temporaries in case they need interface conversion.
// temporaries if they may need interface conversion.
Expression*
Struct_construction_expression::do_flatten(Gogo*, Named_object*,
@ -15155,10 +15155,13 @@ Struct_construction_expression::do_flatten(Gogo*, Named_object*,
return this;
Location loc = this->location();
const Struct_field_list* fields = this->type_->struct_type()->fields();
Struct_field_list::const_iterator pf = fields->begin();
for (Expression_list::iterator pv = this->vals()->begin();
pv != this->vals()->end();
++pv)
++pv, ++pf)
{
go_assert(pf != fields->end());
if (*pv != NULL)
{
if ((*pv)->is_error_expression() || (*pv)->type()->is_error_type())
@ -15166,7 +15169,8 @@ Struct_construction_expression::do_flatten(Gogo*, Named_object*,
go_assert(saw_errors());
return Expression::make_error(loc);
}
if (!(*pv)->is_multi_eval_safe())
if (pf->type()->interface_type() != NULL
&& !(*pv)->is_multi_eval_safe())
{
Temporary_statement* temp =
Statement::make_temporary(NULL, *pv, loc);
@ -15441,7 +15445,7 @@ Array_construction_expression::do_check_types(Gogo*)
}
// Flatten an array construction expression. Store the values into
// temporaries in case they need interface conversion.
// temporaries if they may need interface conversion.
Expression*
Array_construction_expression::do_flatten(Gogo*, Named_object*,
@ -15460,6 +15464,11 @@ Array_construction_expression::do_flatten(Gogo*, Named_object*,
if (this->is_constant_array() || this->is_static_initializer())
return this;
// If the array element type is not an interface type, we don't need
// temporaries.
if (this->type_->array_type()->element_type()->interface_type() == NULL)
return this;
Location loc = this->location();
for (Expression_list::iterator pv = this->vals()->begin();
pv != this->vals()->end();