From: Jakub Jelinek <jakub@redhat.com>
Date: Thu, 12 Aug 2010 15:28:40 +0000 (+0200)
Subject: re PR middle-end/45262 (Optimization results in wrong result on expression x>>31... 
X-Git-Tag: releases/gcc-4.4.5~143
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=68bd7fdeace07bd6c46cef43884eefbd3e6751da;p=thirdparty%2Fgcc.git

re PR middle-end/45262 (Optimization results in wrong result on expression x>>31||(-x)>>31)

	PR middle-end/45262
	* fold-const.c (make_range) <case NEGATE_EXPR>: Punt if
	-a overflows.  Normalize the range.

	* gcc.c-torture/execute/pr45262.c: New test.

From-SVN: r163195
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index a60b69822e7b..e33f5e6f8a0b 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2010-08-12  Jakub Jelinek  <jakub@redhat.com>
+
+	PR middle-end/45262
+	* fold-const.c (make_range) <case NEGATE_EXPR>: Punt if
+	-a overflows.  Normalize the range.
+
 2010-08-10  Steve Ellcey  <sje@cup.hp.com>
 	    Jakub Jelinek <jakub@redhat.com>
 
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 192665924f0e..4d5e70d4b268 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -4479,9 +4479,9 @@ make_range (tree exp, int *pin_p, tree *plow, tree *phigh,
 	  n_high = range_binop (MINUS_EXPR, exp_type,
 				build_int_cst (exp_type, 0),
 				0, low, 0);
-	  low = n_low, high = n_high;
-	  exp = arg0;
-	  continue;
+	  if (n_high != 0 && TREE_OVERFLOW (n_high))
+	    break;
+	  goto normalize;
 
 	case BIT_NOT_EXPR:
 	  /* ~ X -> -X - 1  */
@@ -4514,6 +4514,7 @@ make_range (tree exp, int *pin_p, tree *plow, tree *phigh,
 	  if (TYPE_OVERFLOW_UNDEFINED (arg0_type))
 	    *strict_overflow_p = true;
 
+	normalize:
 	  /* Check for an unsigned range which has wrapped around the maximum
 	     value thus making n_high < n_low, and normalize it.  */
 	  if (n_low && n_high && tree_int_cst_lt (n_high, n_low))
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index cf80f396688e..47d8759cbc9a 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2010-08-12  Jakub Jelinek  <jakub@redhat.com>
+
+	PR middle-end/45262
+	* gcc.c-torture/execute/pr45262.c: New test.
+
 2010-08-10  Steve Ellcey  <sje@cup.hp.com>
 
 	Backport from mainline:
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr45262.c b/gcc/testsuite/gcc.c-torture/execute/pr45262.c
new file mode 100644
index 000000000000..72e186bf287f
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr45262.c
@@ -0,0 +1,33 @@
+/* PR middle-end/45262 */
+
+extern void abort (void);
+
+int
+foo (unsigned int x)
+{
+  return ((int) x < 0) || ((int) (-x) < 0);
+}
+
+int
+bar (unsigned int x)
+{
+  return x >> 31 || (-x) >> 31;
+}
+
+int
+main (void)
+{
+  if (foo (1) != 1)
+    abort ();
+  if (foo (0) != 0)
+    abort ();
+  if (foo (-1) != 1)
+    abort ();
+  if (bar (1) != 1)
+    abort ();
+  if (bar (0) != 0)
+    abort ();
+  if (bar (-1) != 1)
+    abort ();
+  return 0;
+}