re PR middle-end/36691 (wrong value left in induction variable)

2008-08-04  Richard Guenther  <rguenther@suse.de>

	PR middle-end/36691
	* tree-ssa-loop-niter.c (number_of_iterations_lt_to_ne): Correctly
	check for no_overflow.

	* gcc.c-torture/execute/pr36691.c: New testcase.

From-SVN: r138645

gcc/ChangeLog

 2008-08-04  Richard Guenther  <rguenther@suse.de>
 
+	PR middle-end/36691
+	* tree-ssa-loop-niter.c (number_of_iterations_lt_to_ne): Correctly
+	check for no_overflow.
+
+2008-08-04  Richard Guenther  <rguenther@suse.de>
+
 	* tree-vect-transform.c (vectorizable_call): Fix tuplification.
 
 2008-08-04  Paul Brook  <paul@codesourcery.com>

gcc/testsuite/ChangeLog

+2008-08-04  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/36691
+	* gcc.c-torture/execute/pr36691.c: New testcase.
+
 2008-08-04  Victor Kaplansky  <victork@il.ibm.com>
 
 	* gcc.dg/vect/vect-complex-5.c: New test.

gcc/testsuite/gcc.c-torture/execute/pr36691.c

+unsigned char g_5;
+
+void func_1 (void)
+{
+  for (g_5 = 9; g_5 >= 4; g_5 -= 5)
+    ;
+}
+
+extern void abort (void);
+int main (void)
+{
+  func_1 ();
+  if (g_5 != 0)
+    abort ();
+  return 0;
+}
+

gcc/tree-ssa-loop-niter.c

@@ -697,7 +697,7 @@ number_of_iterations_lt_to_ne (tree type, affine_iv *iv0, affine_iv *iv1,
       /* The final value of the iv is iv1->base + MOD, assuming that this
 	 computation does not overflow, and that
 	 iv0->base <= iv1->base + MOD.  */
-      if (!iv1->no_overflow && !integer_zerop (mod))
+      if (!iv0->no_overflow && !integer_zerop (mod))
 	{
 	  bound = fold_build2 (MINUS_EXPR, type,
 			       TYPE_MAX_VALUE (type1), tmod);
@@ -719,7 +719,7 @@ number_of_iterations_lt_to_ne (tree type, affine_iv *iv0, affine_iv *iv1,
       /* The final value of the iv is iv0->base - MOD, assuming that this
 	 computation does not overflow, and that
 	 iv0->base - MOD <= iv1->base. */
-      if (!iv0->no_overflow && !integer_zerop (mod))
+      if (!iv1->no_overflow && !integer_zerop (mod))
 	{
 	  bound = fold_build2 (PLUS_EXPR, type1,
 			       TYPE_MIN_VALUE (type1), tmod);