From 37e10165c13e9860dabbf6eaf85481debec459e9 Mon Sep 17 00:00:00 2001
From: Teresa Johnson <tejohnson@google.com>
Date: Thu, 13 Nov 2014 15:36:48 +0000
Subject: [PATCH] re PR tree-optimization/63841 (Incorrect strlen optimization
after complete unroll)
2014-11-13 Teresa Johnson <tejohnson@google.com>
gcc:
PR tree-optimization/63841
* tree.c (initializer_zerop): A clobber does not zero initialize.
gcc/testsuite:
PR tree-optimization/63841
* g++.dg/tree-ssa/pr63841.C: New test.
From-SVN: r217505
---
gcc/ChangeLog | 5 ++++
gcc/testsuite/ChangeLog | 4 +++
gcc/testsuite/g++.dg/tree-ssa/pr63841.C | 38 +++++++++++++++++++++++++
gcc/tree.c | 2 ++
4 files changed, 49 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/tree-ssa/pr63841.C
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index dca1d5a3da0a..c6014e993a39 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2014-11-13 Teresa Johnson <tejohnson@google.com>
+
+ PR tree-optimization/63841
+ * tree.c (initializer_zerop): A clobber does not zero initialize.
+
2014-11-13 Ulrich Weigand <Ulrich.Weigand@de.ibm.com>
* optabs.c (prepare_operand): Gracefully fail if the mode of X
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 279c1b4a5749..b4484b62b0da 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2014-11-13 Teresa Johnson <tejohnson@google.com>
+ PR tree-optimization/63841
+ * g++.dg/tree-ssa/pr63841.C: New test.
+
2014-11-13 Richard Biener <rguenther@suse.de>
* gcc.dg/tree-ssa/forwprop-28.c: Adjust.
diff --git a/gcc/testsuite/g++.dg/tree-ssa/pr63841.C b/gcc/testsuite/g++.dg/tree-ssa/pr63841.C
new file mode 100644
index 000000000000..466e320d431c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/tree-ssa/pr63841.C
@@ -0,0 +1,38 @@
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+
+#include <cstdio>
+#include <string>
+
+std::string __attribute__ ((noinline)) comp_test_write() {
+ std::string data;
+
+ for (int i = 0; i < 2; ++i) {
+ char b = 1 >> (i * 8);
+ data.append(&b, 1);
+ }
+
+ return data;
+}
+
+std::string __attribute__ ((noinline)) comp_test_write_good() {
+ std::string data;
+
+ char b;
+ for (int i = 0; i < 2; ++i) {
+ b = 1 >> (i * 8);
+ data.append(&b, 1);
+ }
+
+ return data;
+}
+
+int main() {
+ std::string good = comp_test_write_good();
+ printf("expected: %hx\n", *(short*)good.c_str());
+
+ std::string bad = comp_test_write();
+ printf("got: %hx\n", *(short*)bad.c_str());
+
+ return good != bad;
+}
diff --git a/gcc/tree.c b/gcc/tree.c
index 221f0dd3d578..cf37a1980c41 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -10330,6 +10330,8 @@ initializer_zerop (const_tree init)
{
unsigned HOST_WIDE_INT idx;
+ if (TREE_CLOBBER_P (init))
+ return false;
FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (init), idx, elt)
if (!initializer_zerop (elt))
return false;
--
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