*** empty log message ***

From-SVN: r1030

diff --git a/gcc/jump.c b/gcc/jump.c
index 60d74a148a84a42274cc8f1a37111d1f6a7b6a1b..b7660fffefa824f562b826e3c5fb81f31dc9b5bd 100644 (file)
--- a/gcc/jump.c
+++ b/gcc/jump.c
@@ -952,16 +952,37 @@ jump_optimize (f, cross_jump, noop_moves, after_regscan)
              && (temp3 = get_condition (insn, &temp4)) != 0
              && can_reverse_comparison_p (temp3, insn))
            {
-             rtx target, seq;
+             rtx temp6, target = 0, seq, init_insn = 0, init = temp2;
              enum rtx_code code = reverse_condition (GET_CODE (temp3));
 
              start_sequence ();
 
-             target = emit_store_flag (gen_reg_rtx (GET_MODE (temp2)), code,
-                                       XEXP (temp3, 0), XEXP (temp3, 1),
-                                       VOIDmode,
-                                       (code == LTU || code == LEU
-                                        || code == GTU || code == GEU), 1);
+             /* It must be the case that TEMP2 is not modified in the range
+                [TEMP4, INSN).  The one exception we make is if the insn
+                before INSN sets TEMP2 to something which is also unchanged
+                in that range.  In that case, we can move the initialization
+                into our sequence.  */
+
+             if ((temp5 = prev_active_insn (insn)) != 0
+                 && GET_CODE (temp5) == INSN
+                 && (temp6 = single_set (temp5)) != 0
+                 && rtx_equal_p (temp2, SET_DEST (temp6))
+                 && (CONSTANT_P (SET_SRC (temp6))
+                     || GET_CODE (SET_SRC (temp6)) == REG
+                     || GET_CODE (SET_SRC (temp6)) == SUBREG))
+               {
+                 emit_insn (PATTERN (temp5));
+                 init_insn = temp5;
+                 init = SET_SRC (temp6);
+               }
+
+             if (CONSTANT_P (init)
+                 || ! reg_set_between_p (init, PREV_INSN (temp4), insn))
+               target = emit_store_flag (gen_reg_rtx (GET_MODE (temp2)), code,
+                                         XEXP (temp3, 0), XEXP (temp3, 1),
+                                         VOIDmode,
+                                         (code == LTU || code == LEU
+                                          || code == GTU || code == GEU), 1);
 
              /* If we can do the store-flag, do the addition or
                 subtraction.  */
@@ -987,6 +1008,10 @@ jump_optimize (f, cross_jump, noop_moves, after_regscan)
 
                  emit_insns_before (seq, temp4);
                  delete_insn (temp);
+
+                 if (init_insn)
+                   delete_insn (init_insn);
+
                  next = NEXT_INSN (insn);
 #ifdef HAVE_cc0
                  delete_insn (prev_nonnote_insn (insn));