PR tree-optimization/26859

	* tree-ssa-loop-niter.c (infer_loop_bounds_from_undefined): Avoid
	division by zero.
	(convert_step): Remove TREE_OVERFLOW and TREE_CONSTANT_OVERFLOW flags
	for the step after fold_convert.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@112502 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 19e54d9..274c94d 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2006-03-29  Sebastian Pop  <pop@cri.ensmp.fr>
+
+       PR tree-optimization/26859
+       * tree-ssa-loop-niter.c (infer_loop_bounds_from_undefined): Avoid
+       division by zero.
+       (convert_step): Remove TREE_OVERFLOW and TREE_CONSTANT_OVERFLOW flags
+       for the step after fold_convert.
+
 2006-03-29  Paul Brook  <paul@codesourcery.com>
 
        * reload1.c (choose_reload_regs): Check for all RTX_AUTOINC operators.

diff --git a/gcc/tree-ssa-loop-niter.c b/gcc/tree-ssa-loop-niter.c
index f7319b2..364c610 100644 (file)
--- a/gcc/tree-ssa-loop-niter.c
+++ b/gcc/tree-ssa-loop-niter.c
@@ -1582,9 +1582,13 @@ infer_loop_bounds_from_undefined (struct loop *loop)
                      diff = fold_build2 (MINUS_EXPR, utype,
                                          TYPE_MAX_VALUE (type), init);
 
-                   estimation = fold_build2 (CEIL_DIV_EXPR, utype, diff,
-                                             step);
-                   record_estimate (loop, estimation, boolean_true_node, stmt);
+                   if (!integer_zerop (step))
+                     {
+                       estimation = fold_build2 (CEIL_DIV_EXPR, utype, diff,
+                                                 step);
+                       record_estimate (loop, estimation, boolean_true_node,
+                                        stmt);
+                     }
                  }
 
                break;
@@ -2090,7 +2094,7 @@ tree
 convert_step (struct loop *loop, tree new_type, tree base, tree step,
              tree at_stmt)
 {
-  tree base_type;
+  tree res, base_type;
 
   if (chrec_contains_undetermined (base)
       || chrec_contains_undetermined (step))
@@ -2100,12 +2104,22 @@ convert_step (struct loop *loop, tree new_type, tree base, tree step,
 
   /* When not using wrapping arithmetic, signed types don't wrap.  */
   if (!flag_wrapv && !TYPE_UNSIGNED (base_type))
-    return fold_convert (new_type, step);
+    goto do_convert_step;
 
   if (TYPE_PRECISION (new_type) > TYPE_PRECISION (base_type))
     return convert_step_widening (loop, new_type, base, step, at_stmt);
 
-  return fold_convert (new_type, step);
+ do_convert_step:
+  
+  res = fold_convert (new_type, step);
+
+  if (TREE_CODE (res) == INTEGER_CST)
+    {
+      TREE_OVERFLOW (res) = 0;
+      TREE_CONSTANT_OVERFLOW (res) = 0;
+    }
+
+  return res;
 }
 
 /* Frees the information on upper bounds on numbers of iterations of LOOP.  */