On Wed, Mar 22, 2017 at 09:59:09AM +0100, Richard Biener wrote:
> Yeah, changing it to VAR_P and expanding the comment so it says
> it avoids incorrect promotion to readonly-static. (so it _is_
> fishy that we have multiple assignments to TREE_READONLY objects
> given that code looks at a single assignment only)
So like this?
2017-03-22 Jakub Jelinek <ja...@redhat.com>
PR c++/80129
* gimplify.c (gimplify_modify_expr_rhs) <case COND_EXPR>: Clear
TREE_READONLY on result if writing it more than once.
* g++.dg/torture/pr80129.C: New test.
--- gcc/gimplify.c.jj 2017-03-21 07:56:55.000000000 +0100
+++ gcc/gimplify.c 2017-03-21 13:37:45.555612652 +0100
@@ -5098,6 +5098,14 @@ gimplify_modify_expr_rhs (tree *expr_p,
if (ret != GS_ERROR)
ret = GS_OK;
+ /* If we are going to write RESULT more than once, clear
+ TREE_READONLY flag, otherwise we might incorrectly promote
+ the variable to static const and initialize it at compile
+ time in one of the branches. */
+ if (VAR_P (result)
+ && TREE_TYPE (TREE_OPERAND (cond, 1)) != void_type_node
+ && TREE_TYPE (TREE_OPERAND (cond, 2)) != void_type_node)
+ TREE_READONLY (result) = 0;
if (TREE_TYPE (TREE_OPERAND (cond, 1)) != void_type_node)
TREE_OPERAND (cond, 1)
= build2 (code, void_type_node, result,
--- gcc/testsuite/g++.dg/torture/pr80129.C.jj 2017-03-21 13:40:04.179852313
+0100
+++ gcc/testsuite/g++.dg/torture/pr80129.C 2017-03-21 13:41:32.121735570
+0100
@@ -0,0 +1,14 @@
+// PR c++/80129
+// { dg-do run }
+// { dg-options "-std=c++11" }
+
+struct A { bool a; int b; };
+
+int
+main ()
+{
+ bool c = false;
+ const A x = c ? A {true, 1} : A {false, 0};
+ if (x.a)
+ __builtin_abort ();
+}
Jakub
