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compiler: don't use address of temporary for deferred delete

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This CL corrects the handling of a deferred delete in a loop, to not
    use a temporary whose value will, at deferred execution time, wind up
    being the last value in the loop.
    
    The test for this is TestDeferDeleteSlow in the 1.11 runtime package.
    
    Reviewed-on: https://go-review.googlesource.com/135358

From-SVN: r264325
This commit is contained in:
Ian Lance Taylor 2018-09-14 16:55:41 +00:00
parent 98ef99ab97
commit 2a7ba9243e
3 changed files with 53 additions and 6 deletions
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2
gcc/go/gofrontend/MERGE
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@ -1,4 +1,4 @@
218c9159635e06e39ae43d0efe1ac1e694fead2e
3fd61802286c81e5fb672f682d9e661181184d1f
The first line of this file holds the git revision number of the last
merge done from the gofrontend repository.

47
gcc/go/gofrontend/expressions.cc
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@ -7409,7 +7409,32 @@ Builtin_call_expression::do_lower(Gogo*, Named_object* function,
loc);
Expression* e3 = Expression::make_temporary_reference(key_temp,
loc);
e3 = Expression::make_unary(OPERATOR_AND, e3, loc);
// If the call to delete is deferred, and is in a loop,
// then the loop will only have a single instance of the
// temporary variable. Passing the address of the
// temporary variable here means that the deferred call
// will see the last value in the loop, not the current
// value. So for this unusual case copy the value into
// the heap.
if (!this->is_deferred())
e3 = Expression::make_unary(OPERATOR_AND, e3, loc);
else
{
Expression* a = Expression::make_allocation(mt->key_type(),
loc);
Temporary_statement* atemp =
Statement::make_temporary(NULL, a, loc);
inserter->insert(atemp);
a = Expression::make_temporary_reference(atemp, loc);
a = Expression::make_dereference(a, NIL_CHECK_NOT_NEEDED, loc);
Statement* s = Statement::make_assignment(a, e3, loc);
inserter->insert(s);
e3 = Expression::make_temporary_reference(atemp, loc);
}
return Runtime::make_call(Runtime::MAPDELETE, this->location(),
3, e1, e2, e3);
}
@ -9024,6 +9049,10 @@ Builtin_call_expression::do_copy()
if (this->varargs_are_lowered())
bce->set_varargs_are_lowered();
if (this->is_deferred())
bce->set_is_deferred();
if (this->is_concurrent())
bce->set_is_concurrent();
return bce;
}
@ -9606,8 +9635,16 @@ Call_expression::do_lower(Gogo* gogo, Named_object* function,
// Recognize a call to a builtin function.
if (fntype->is_builtin())
return new Builtin_call_expression(gogo, this->fn_, this->args_,
this->is_varargs_, loc);
{
Builtin_call_expression* bce =
new Builtin_call_expression(gogo, this->fn_, this->args_,
this->is_varargs_, loc);
if (this->is_deferred_)
bce->set_is_deferred();
if (this->is_concurrent_)
bce->set_is_concurrent();
return bce;
}
// If this call returns multiple results, create a temporary
// variable to hold them.
@ -10275,6 +10312,10 @@ Call_expression::do_copy()
if (this->varargs_are_lowered_)
call->set_varargs_are_lowered();
if (this->is_deferred_)
call->set_is_deferred();
if (this->is_concurrent_)
call->set_is_concurrent();
return call;
}

10
gcc/go/gofrontend/parse.cc
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@ -4304,9 +4304,15 @@ Parse::go_or_defer_stat()
this->gogo_->start_block(stat_location);
Statement* stat;
if (is_go)
stat = Statement::make_go_statement(call_expr, stat_location);
{
stat = Statement::make_go_statement(call_expr, stat_location);
call_expr->set_is_concurrent();
}
else
stat = Statement::make_defer_statement(call_expr, stat_location);
{
stat = Statement::make_defer_statement(call_expr, stat_location);
call_expr->set_is_deferred();
}
this->gogo_->add_statement(stat);
this->gogo_->add_block(this->gogo_->finish_block(stat_location),
stat_location);