* ifcvt.c (noce_try_store_flag_constants): Test for overflow

        in computing DIFF.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@47374 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 2d60935..ab35538 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2001-11-27  Richard Henderson  <rth@redhat.com>
+
+       * ifcvt.c (noce_try_store_flag_constants): Test for overflow
+       in computing DIFF.
+
 2001-11-27  Zack Weinberg  <zack@codesourcery.com>
 
        * cppfiles.c (read_include_file): Add comment.

diff --git a/gcc/ifcvt.c b/gcc/ifcvt.c
index 5dd42fc..f6a07e9 100644 (file)
--- a/gcc/ifcvt.c
+++ b/gcc/ifcvt.c
@@ -650,6 +650,12 @@ noce_try_store_flag_constants (if_info)
       mode = GET_MODE (if_info->x);
       ifalse = INTVAL (if_info->a);
       itrue = INTVAL (if_info->b);
+
+      /* Make sure we can represent the difference between the two values.  */
+      if ((itrue - ifalse > 0)
+         != ((ifalse < 0) != (itrue < 0) ? ifalse < 0 : ifalse < itrue))
+       return FALSE;
+
       diff = trunc_int_for_mode (itrue - ifalse, mode);
 
       can_reverse = (reversed_comparison_code (if_info->cond, if_info->jump)