From patchwork Fri Nov 26 08:57:41 2010
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Subject: Another builtin memset fix (PR middle-end/46647)
Date: Thu, 25 Nov 2010 22:57:41 -0000
From: Jakub Jelinek <jakub@redhat.com>
X-Patchwork-Id: 73162
Message-Id: <20101126085741.GK29412@tyan-ft48-01.lab.bos.redhat.com>
To: gcc-patches@gcc.gnu.org

Hi!

While H.J's patch fixed memset expansion with regard to negative
second argument, this patch does the same for memset folding.
We don't really care about any upper bits, only the low 8 bits matter.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2010-11-26  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/46647
	* builtins.c (fold_builtin_memset): Check c is INTEGER_CST instead
	of host_integerp check.  Use TREE_INT_CST_LOW instead of tree_low_cst.

	* gcc.dg/pr46647.c: New test.


	Jakub


--- gcc/builtins.c.jj	2010-11-19 20:56:54.000000000 +0100
+++ gcc/builtins.c	2010-11-24 22:23:41.000000000 +0100
@@ -8345,7 +8345,7 @@ fold_builtin_memset (location_t loc, tre
   if (integer_zerop (len))
     return omit_one_operand_loc (loc, type, dest, c);
 
-  if (! host_integerp (c, 1) || TREE_SIDE_EFFECTS (dest))
+  if (TREE_CODE (c) != INTEGER_CST || TREE_SIDE_EFFECTS (dest))
     return NULL_TREE;
 
   var = dest;
@@ -8384,7 +8384,7 @@ fold_builtin_memset (location_t loc, tre
       if (CHAR_BIT != 8 || BITS_PER_UNIT != 8 || HOST_BITS_PER_WIDE_INT > 64)
 	return NULL_TREE;
 
-      cval = tree_low_cst (c, 1);
+      cval = TREE_INT_CST_LOW (c);
       cval &= 0xff;
       cval |= cval << 8;
       cval |= cval << 16;
--- gcc/testsuite/gcc.dg/pr46647.c.jj	2010-11-25 21:28:03.000000000 +0100
+++ gcc/testsuite/gcc.dg/pr46647.c	2010-11-25 21:29:57.000000000 +0100
@@ -0,0 +1,29 @@
+/* PR middle-end/46647 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+int a;
+
+int
+func1 (void)
+{
+  __builtin_memset (&a, -1, sizeof (a));
+  return 0;
+}
+
+int
+func2 (void)
+{
+  __builtin_memset (&a, 123, sizeof (a));
+  return 0;
+}
+
+int
+func3 (void)
+{
+  __builtin_memset (&a, 0, sizeof (a));
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump-not "memset" "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */