From: Zdenek Dvorak <dvorakz@suse.cz>
Date: Wed, 22 Nov 2006 23:11:15 +0000 (+0100)
Subject: re PR tree-optimization/29921 (internal compiler error: in set_lattice_value, at... 
X-Git-Tag: releases/gcc-4.3.0~8328
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0446c9f3a7f86ed71112170e8e9023d3ac526dde;p=thirdparty%2Fgcc.git

re PR tree-optimization/29921 (internal compiler error: in set_lattice_value, at tree-ssa-ccp.c:437)

	PR tree-optimization/29921
	* fold-const.c (operand_equal_p): Without HONOR_SIGNED_ZEROS, consider
	signed and unsigned zero equal.

	* gcc.dg/pr29921.c: New test.

From-SVN: r119102
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c6fdb9f1830f..5bb0ce3bfc60 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2006-11-23  Zdenek Dvorak <dvorakz@suse.cz>
+
+	PR tree-optimization/29921
+	* fold-const.c (operand_equal_p): Without HONOR_SIGNED_ZEROS, consider
+	signed and unsigned zero equal.
+
 2006-11-22  Peter Bergner  <bergner@vnet.ibm.com>
 
 	* config/rs6000/rs6000.c (get_store_dest): New.
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index cd7f1d9e8316..b19b7688a2dc 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -2584,8 +2584,19 @@ operand_equal_p (tree arg0, tree arg1, unsigned int flags)
 	return tree_int_cst_equal (arg0, arg1);
 
       case REAL_CST:
-	return REAL_VALUES_IDENTICAL (TREE_REAL_CST (arg0),
-				      TREE_REAL_CST (arg1));
+	if (REAL_VALUES_IDENTICAL (TREE_REAL_CST (arg0),
+				   TREE_REAL_CST (arg1)))
+	  return 1;
+
+	
+	if (!HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg0))))
+	  {
+	    /* If we do not distinguish between signed and unsigned zero,
+	       consider them equal.  */
+	    if (real_zerop (arg0) && real_zerop (arg1))
+	      return 1;
+	  }
+	return 0;
 
       case VECTOR_CST:
 	{
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index ff2a80dad5b1..f8dc647d4e0c 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2006-11-23  Zdenek Dvorak <dvorakz@suse.cz>
+
+	PR tree-optimization/29921
+	* gcc.dg/pr29921.c: New test.
+
 2006-11-22  Tobias Schlueter  <tobias.schlueter@physik.uni-muenchen.de>
 
 	PR fortran/29441
diff --git a/gcc/testsuite/gcc.dg/pr29921.c b/gcc/testsuite/gcc.dg/pr29921.c
new file mode 100644
index 000000000000..7689f54ce250
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr29921.c
@@ -0,0 +1,20 @@
+/* With -ffast-math, the latice value for t changes from -0.0 to 0.0 in this
+   testcase.  */
+
+/* { dg-do compile } */
+/* { dg-options "-O2 -ffast-math" } */
+
+double test (int param)
+{
+  double a = 0.0, b = -1.0, t;
+  int i;
+
+  for (i = 0; i < 100; i++)
+    {
+      t = a * b;
+      if (param)
+	b = 2.0;
+    }
+
+  return t;
+}