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2017-05-30 Jakub Jelinek <jakub@redhat.com>
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Backported from mainline
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2017-03-22 Jakub Jelinek <jakub@redhat.com>
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PR c++/80129
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* gimplify.c (gimplify_modify_expr_rhs) <case COND_EXPR>: Clear
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TREE_READONLY on result if writing it more than once.
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* g++.dg/torture/pr80129.C: New test.
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--- gcc/gimplify.c
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+++ gcc/gimplify.c
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@@ -4293,6 +4293,14 @@ gimplify_modify_expr_rhs (tree *expr_p, tree *from_p, tree *to_p,
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if (ret != GS_ERROR)
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ret = GS_OK;
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+ /* If we are going to write RESULT more than once, clear
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+ TREE_READONLY flag, otherwise we might incorrectly promote
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+ the variable to static const and initialize it at compile
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+ time in one of the branches. */
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+ if (TREE_CODE (result) == VAR_DECL
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+ && TREE_TYPE (TREE_OPERAND (cond, 1)) != void_type_node
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+ && TREE_TYPE (TREE_OPERAND (cond, 2)) != void_type_node)
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+ TREE_READONLY (result) = 0;
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if (TREE_TYPE (TREE_OPERAND (cond, 1)) != void_type_node)
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TREE_OPERAND (cond, 1)
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= build2 (code, void_type_node, result,
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--- /dev/null
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+++ gcc/testsuite/g++.dg/torture/pr80129.C
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@@ -0,0 +1,14 @@
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+// PR c++/80129
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+// { dg-do run }
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+// { dg-options "-std=c++11" }
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+
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+struct A { bool a; int b; };
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+
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+int
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+main ()
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+{
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+ bool c = false;
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+ const A x = c ? A {true, 1} : A {false, 0};
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+ if (x.a)
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+ __builtin_abort ();
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+}
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