compare-elim.c (find_comparisons_in_bb): Eliminate only compares having mode compatib...

	* compare-elim.c (find_comparisons_in_bb): Eliminate only compares
	having mode compatible with the mode of previous compare.  Substitute
	compare mode of previous compare with the mode, compatible
	with eliminated and previous compare.

From-SVN: r184816

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b7e3db3..811702c 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2012-03-02  Uros Bizjak  <ubizjak@gmail.com>
+
+       * compare-elim.c (find_comparisons_in_bb): Eliminate only compares
+       having mode compatible with the mode of previous compare.  Substitute
+       compare mode of previous compare with the mode, compatible
+       with eliminated and previous compare.
+
 2012-03-02  Peter Bergner  <bergner@vnet.ibm.com>
 
        * config/rs6000/dfp.md (floatdidd2): New define_insn.

diff --git a/gcc/compare-elim.c b/gcc/compare-elim.c
index 15d8d62..5157e76 100644 (file)
--- a/gcc/compare-elim.c
+++ b/gcc/compare-elim.c
@@ -301,15 +301,37 @@ find_comparisons_in_bb (struct dom_walk_data *data ATTRIBUTE_UNUSED,
 
          /* Eliminate a compare that's redundant with the previous.  */
          if (last_cmp_valid
-             && src_mode == last_cmp->orig_mode
              && rtx_equal_p (last_cmp->in_a, XEXP (src, 0))
              && rtx_equal_p (last_cmp->in_b, XEXP (src, 1)))
            {
+             rtx flags, x;
+             enum machine_mode new_mode
+               = targetm.cc_modes_compatible (last_cmp->orig_mode, src_mode);
+
+             /* New mode is incompatible with the previous compare mode.  */
+             if (new_mode == VOIDmode)
+               continue;
+
+             if (new_mode != last_cmp->orig_mode)
+               {
+                 flags = gen_rtx_REG (src_mode, targetm.flags_regnum);
+
+                 /* Generate new comparison for substitution.  */
+                 x = gen_rtx_COMPARE (new_mode, XEXP (src, 0), XEXP (src, 1));
+                 x = gen_rtx_SET (VOIDmode, flags, x);
+
+                 if (!validate_change (last_cmp->insn,
+                                       &PATTERN (last_cmp->insn), x, false))
+                   continue;
+
+                 last_cmp->orig_mode = new_mode;
+               }
+
              delete_insn (insn);
              continue;
            }
 
-          last_cmp = XCNEW (struct comparison);
+         last_cmp = XCNEW (struct comparison);
          last_cmp->insn = insn;
          last_cmp->prev_clobber = last_clobber;
          last_cmp->in_a = XEXP (src, 0);