From: Jakub Jelinek <jakub@redhat.com>
Date: Wed, 7 May 2014 16:05:38 +0000 (+0200)
Subject: backport: re PR middle-end/58564 (possible wrong code bug at -O0)
X-Git-Tag: releases/gcc-4.7.4~102
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=11d82e337418fa5502adb8edd3ef4a51b30e8991;p=thirdparty%2Fgcc.git

backport: re PR middle-end/58564 (possible wrong code bug at -O0)

	Backported from mainline
	2013-09-30  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/58564
	* fold-const.c (fold_ternary_loc): For A < 0 : <sign bit of A> : 0
	optimization, punt if sign_bit_p looked through any zero extension.

	* gcc.c-torture/execute/pr58564.c: New test.

From-SVN: r210174
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 139a579103a8..940ed0fb7c06 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,6 +1,12 @@
 2014-05-07  Jakub Jelinek  <jakub@redhat.com>
 
 	Backported from mainline
+	2013-09-30  Jakub Jelinek  <jakub@redhat.com>
+
+	PR middle-end/58564
+	* fold-const.c (fold_ternary_loc): For A < 0 : <sign bit of A> : 0
+	optimization, punt if sign_bit_p looked through any zero extension.
+
 	2013-09-10  Jakub Jelinek  <jakub@redhat.com>
 
 	PR rtl-optimization/58365
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 804a05f927a0..d83f084dd038 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -13849,14 +13849,29 @@ fold_ternary_loc (location_t loc, enum tree_code code, tree type,
 	  && integer_zerop (op2)
 	  && (tem = sign_bit_p (TREE_OPERAND (arg0, 0), arg1)))
 	{
+	  /* sign_bit_p looks through both zero and sign extensions,
+	     but for this optimization only sign extensions are
+	     usable.  */
+	  tree tem2 = TREE_OPERAND (arg0, 0);
+	  while (tem != tem2)
+	    {
+	      if (TREE_CODE (tem2) != NOP_EXPR
+		  || TYPE_UNSIGNED (TREE_TYPE (TREE_OPERAND (tem2, 0))))
+		{
+		  tem = NULL_TREE;
+		  break;
+		}
+	      tem2 = TREE_OPERAND (tem2, 0);
+	    }
 	  /* sign_bit_p only checks ARG1 bits within A's precision.
 	     If <sign bit of A> has wider type than A, bits outside
 	     of A's precision in <sign bit of A> need to be checked.
 	     If they are all 0, this optimization needs to be done
 	     in unsigned A's type, if they are all 1 in signed A's type,
 	     otherwise this can't be done.  */
-	  if (TYPE_PRECISION (TREE_TYPE (tem))
-	      < TYPE_PRECISION (TREE_TYPE (arg1))
+	  if (tem
+	      && TYPE_PRECISION (TREE_TYPE (tem))
+		 < TYPE_PRECISION (TREE_TYPE (arg1))
 	      && TYPE_PRECISION (TREE_TYPE (tem))
 		 < TYPE_PRECISION (type))
 	    {
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 362317863b61..b28b8ad0dce9 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,6 +1,11 @@
 2014-05-07  Jakub Jelinek  <jakub@redhat.com>
 
 	Backported from mainline
+	2013-09-30  Jakub Jelinek  <jakub@redhat.com>
+
+	PR middle-end/58564
+	* gcc.c-torture/execute/pr58564.c: New test.
+
 	2013-09-10  Jakub Jelinek  <jakub@redhat.com>
 
 	PR rtl-optimization/58365
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr58564.c b/gcc/testsuite/gcc.c-torture/execute/pr58564.c
new file mode 100644
index 000000000000..967ee95d4abc
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr58564.c
@@ -0,0 +1,14 @@
+/* PR middle-end/58564 */
+
+extern void abort (void);
+int a, b;
+short *c, **d = &c;
+
+int
+main ()
+{
+  b = (0, 0 > ((&c == d) & (1 && (a ^ 1)))) | 0U;
+  if (b != 0)
+    abort ();
+  return 0;
+}