From: Jakub Jelinek <jakub@redhat.com>
Date: Fri, 16 Dec 2005 12:12:41 +0000 (+0100)
Subject: re PR rtl-optimization/24899 (loop.c miscompiles libgnomecanvas)
X-Git-Tag: releases/gcc-4.2.0~5303
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a1615718f5f7eae8acb173637725808d02bb9c00;p=thirdparty%2Fgcc.git

re PR rtl-optimization/24899 (loop.c miscompiles libgnomecanvas)

	PR rtl-optimization/24899
	* loop.c (strength_reduce): Don't reduce giv that is not always
	computable and where add_val or mult_val can trap.

	* gcc.c-torture/execute/20051215-1.c: New test.

From-SVN: r108642
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index ccebcd768705..f5e91e609fbe 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,9 @@
 2005-12-16  Jakub Jelinek  <jakub@redhat.com>
 
+	PR rtl-optimization/24899
+	* loop.c (strength_reduce): Don't reduce giv that is not always
+	computable and where add_val or mult_val can trap.
+
 	* doc/invoke.texi (-fdump-tree-*): Remove note about C/C++ only.
 
 2005-12-16  Nathan Sidwell  <nathan@codesourcery.com>
diff --git a/gcc/loop.c b/gcc/loop.c
index 0de77beab362..4aa1ff9ab707 100644
--- a/gcc/loop.c
+++ b/gcc/loop.c
@@ -6486,6 +6486,17 @@ strength_reduce (struct loop *loop, int flags)
 	      v->ignore = 1;
 	      bl->all_reduced = 0;
 	    }
+	  else if (!v->always_computable
+		   && (may_trap_or_fault_p (v->add_val)
+		       || may_trap_or_fault_p (v->mult_val)))
+	    {
+	      if (loop_dump_stream)
+		fprintf (loop_dump_stream,
+			 "giv of insn %d: not always computable.\n",
+			 INSN_UID (v->insn));
+	      v->ignore = 1;
+	      bl->all_reduced = 0;
+	    }
 	  else
 	    {
 	      /* Check that we can increment the reduced giv without a
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 8c498964ce5d..075dd3b615e2 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2005-12-16  Jakub Jelinek  <jakub@redhat.com>
+
+	PR rtl-optimization/24899
+	* gcc.c-torture/execute/20051215-1.c: New test.
+
 2005-12-16  Andreas Krebbel  <krebbel1@de.ibm.com>
 
 	PR 24823
diff --git a/gcc/testsuite/gcc.c-torture/execute/20051215-1.c b/gcc/testsuite/gcc.c-torture/execute/20051215-1.c
new file mode 100644
index 000000000000..143a449d080c
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/20051215-1.c
@@ -0,0 +1,28 @@
+/* PR rtl-optimization/24899 */
+
+extern void abort (void);
+
+__attribute__ ((noinline)) int
+foo (int x, int y, int *z)
+{
+  int a, b, c, d;
+
+  a = b = 0;
+  for (d = 0; d < y; d++)
+    {
+      if (z)
+	b = d * *z;
+      for (c = 0; c < x; c++)
+	a += b;
+    }
+
+  return a;
+}
+
+int
+main (void)
+{
+  if (foo (3, 2, 0) != 0)
+    abort ();
+  return 0;
+}