Go patch committed: Fix double evaluation when using interface field expression
Ian Lance Taylor
iant@golang.org
Tue Jul 10 00:55:00 GMT 2018
This patch to the Go frontend by Cherry Zhang fixes the compiler to
avoid a double evaluation of an interface field expression. In
Interface_field_reference_expression, the interface expression is used
in two places, so a temporary variable is used. Previously, we used a
Set_and_use_temporary_expression, which, when evaluated twice, causes
double evaluation of the underlying expression. Fix by setting the
temporary once and use Temporary_reference_expression instead.
This fixes https://golang.org/issue/26248. The test case for this is
in https://golang.org/cl/122757.
Bootstrapped and ran Go testsuite on x86_64-pc-linux-gnu. Committed
to mainline.
Ian
-------------- next part --------------
Index: gcc/go/gofrontend/MERGE
===================================================================
--- gcc/go/gofrontend/MERGE (revision 262313)
+++ gcc/go/gofrontend/MERGE (working copy)
@@ -1,4 +1,4 @@
-94738979a3422e845acf358a766aabf8b9275d43
+8ad67a72a4fa59efffc891e73ecf10020e3c565d
The first line of this file holds the git revision number of the last
merge done from the gofrontend repository.
Index: gcc/go/gofrontend/expressions.cc
===================================================================
--- gcc/go/gofrontend/expressions.cc (revision 262312)
+++ gcc/go/gofrontend/expressions.cc (working copy)
@@ -11886,10 +11886,9 @@ Interface_field_reference_expression::do
if (!this->expr_->is_variable())
{
Temporary_statement* temp =
- Statement::make_temporary(this->expr_->type(), NULL, this->location());
+ Statement::make_temporary(NULL, this->expr_, this->location());
inserter->insert(temp);
- this->expr_ = Expression::make_set_and_use_temporary(temp, this->expr_,
- this->location());
+ this->expr_ = Expression::make_temporary_reference(temp, this->location());
}
return this;
}
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