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compiler: Analyze escape information of interface parameters.

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When analyzing function calls with interface parameters, all arguments
related to an interface parameter were assumed to escape via the
function arguments.  Now, if an argument is related to a non-escaping
parameter with an interface type, the argument may be stack-allocated.

From-SVN: r222865
This commit is contained in:
Ian Lance Taylor 2015-05-06 22:59:54 +00:00
parent f1abbf6901
commit 87bde062dd
1 changed files with 16 additions and 12 deletions
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28
gcc/go/gofrontend/escape.cc
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@ -586,8 +586,20 @@ Build_connection_graphs::handle_call(Named_object* object, Expression* e)
// Only call expression statements are interesting
// e.g. 'func(var)' for which we can show var does not escape.
Call_expression* ce = e->call_expression();
if (ce == NULL || ce->args() == NULL)
if (ce == NULL)
return;
else if (ce->args() == NULL)
{
if (ce->fn()->interface_field_reference_expression() != NULL)
{
// This is a call to an interface method with no arguments. OBJECT
// must be the receiver and we assume it escapes.
Connection_node* rcvr_node =
this->gogo_->add_connection_node(object)->connection_node();
rcvr_node->set_escape_state(Node::ESCAPE_ARG);
}
return;
}
// If the function call that references OBJECT is unknown, we must be
// conservative and assume every argument escapes. A function call is unknown
@ -606,6 +618,8 @@ Build_connection_graphs::handle_call(Named_object* object, Expression* e)
this->gogo_->add_connection_node(arg_no)->connection_node();
arg_node->set_escape_state(Node::ESCAPE_ARG);
}
else if ((*arg)->call_expression() != NULL)
this->handle_call(object, *arg);
}
return;
}
@ -787,7 +801,6 @@ Build_connection_graphs::handle_call(Named_object* object, Expression* e)
++pos)
{
std::string param_name;
bool param_is_interface = false;
if (*pos >= 0 && params->size() <= static_cast<size_t>(*pos))
{
// There were more arguments than there are parameters. This must be
@ -804,11 +817,7 @@ Build_connection_graphs::handle_call(Named_object* object, Expression* e)
param_name = fntype->receiver()->name();
}
else
{
param_name = params->at(*pos).name();
param_is_interface =
(params->at(*pos).type()->interface_type() != NULL);
}
param_name = params->at(*pos).name();
if (Gogo::is_sink_name(param_name) || param_name.empty())
continue;
@ -832,11 +841,6 @@ Build_connection_graphs::handle_call(Named_object* object, Expression* e)
Node* arg_node = this->gogo_->add_connection_node(object);
Node* param_node = this->gogo_->add_connection_node(param_no);
// Act conservatively when an argument is converted into an interface
// value. FIXME.
if (param_is_interface)
param_node->connection_node()->set_escape_state(Node::ESCAPE_ARG);
param_node->add_edge(arg_node);
}