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escape: Stack allocate non-escaping expressions.

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Stack allocate expressions that the analysis tracked and determined
    did not escape.
    
    Reviewed-on: https://go-review.googlesource.com/22377

From-SVN: r239083
This commit is contained in:
Ian Lance Taylor 2016-08-03 16:32:17 +00:00
parent 612a6ffe0e
commit 3af8a0a810
2 changed files with 44 additions and 8 deletions
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2
gcc/go/gofrontend/MERGE
View file

@ -1,4 +1,4 @@
89a0b3a04f80df388242166b8835f12e82ceb194
7d6c53910e52b7db2a77c1c1c3bc2c170283a1fa
The first line of this file holds the git revision number of the last
merge done from the gofrontend repository.

50
gcc/go/gofrontend/expressions.cc
View file

@ -252,7 +252,9 @@ Expression::convert_type_to_interface(Type* lhs_type, Expression* rhs,
else
{
// We are assigning a non-pointer value to the interface; the
// interface gets a copy of the value in the heap.
// interface gets a copy of the value in the heap if it escapes.
// TODO(cmang): Associate escape state state of RHS with newly
// created OBJ.
obj = Expression::make_heap_expression(rhs, location);
}
@ -729,6 +731,13 @@ Var_expression::do_address_taken(bool escapes)
else
go_unreachable();
}
if (this->variable_->is_variable()
&& this->variable_->var_value()->is_in_heap())
{
Node::make_node(this)->set_encoding(Node::ESCAPE_HEAP);
Node::make_node(this->variable_)->set_encoding(Node::ESCAPE_HEAP);
}
}
// Get the backend representation for a reference to a variable.
@ -831,6 +840,10 @@ Enclosed_var_expression::do_address_taken(bool escapes)
else
go_unreachable();
}
if (this->variable_->is_variable()
&& this->variable_->var_value()->is_in_heap())
Node::make_node(this->variable_)->set_encoding(Node::ESCAPE_HEAP);
}
// Ast dump for enclosed variable expression.
@ -3769,9 +3782,18 @@ Unary_expression::do_flatten(Gogo* gogo, Named_object*,
// value does not escape. If this->escapes_ is true, we may be
// able to set it to false if taking the address of a variable
// that does not escape.
if (this->escapes_ && this->expr_->var_expression() != NULL)
Node* n = Node::make_node(this);
if ((n->encoding() & ESCAPE_MASK) == int(Node::ESCAPE_NONE))
this->escapes_ = false;
Named_object* var = NULL;
if (this->expr_->var_expression() != NULL)
var = this->expr_->var_expression()->named_object();
else if (this->expr_->enclosed_var_expression() != NULL)
var = this->expr_->enclosed_var_expression()->variable();
if (this->escapes_ && var != NULL)
{
Named_object* var = this->expr_->var_expression()->named_object();
if (var->is_variable())
this->escapes_ = var->var_value()->escapes();
if (var->is_result_variable())
@ -11658,7 +11680,9 @@ Allocation_expression::do_get_backend(Translate_context* context)
Gogo* gogo = context->gogo();
Location loc = this->location();
if (this->allocate_on_stack_)
Node* n = Node::make_node(this);
if (this->allocate_on_stack_
|| (n->encoding() & ESCAPE_MASK) == int(Node::ESCAPE_NONE))
{
int64_t size;
bool ok = this->type_->backend_type_size(gogo, &size);
@ -12344,7 +12368,15 @@ Slice_construction_expression::do_get_backend(Translate_context* context)
space->unary_expression()->set_is_slice_init();
}
else
space = Expression::make_heap_expression(array_val, loc);
{
space = Expression::make_heap_expression(array_val, loc);
Node* n = Node::make_node(this);
if ((n->encoding() & ESCAPE_MASK) == int(Node::ESCAPE_NONE))
{
n = Node::make_node(space);
n->set_encoding(Node::ESCAPE_NONE);
}
}
// Build a constructor for the slice.
@ -13417,8 +13449,12 @@ Heap_expression::do_get_backend(Translate_context* context)
Location loc = this->location();
Gogo* gogo = context->gogo();
Btype* btype = this->type()->get_backend(gogo);
Bexpression* space = Expression::make_allocation(this->expr_->type(),
loc)->get_backend(context);
Expression* alloc = Expression::make_allocation(this->expr_->type(), loc);
Node* n = Node::make_node(this);
if ((n->encoding() & ESCAPE_MASK) == int(Node::ESCAPE_NONE))
alloc->allocation_expression()->set_allocate_on_stack();
Bexpression* space = alloc->get_backend(context);
Bstatement* decl;
Named_object* fn = context->function();