reorg.c (relax_delay_slots): Do not redirect a jump if doing so invalidates insns...

        * reorg.c (relax_delay_slots): Do not redirect a jump if doing so
        invalidates insns in the jump's delay slots.
        (redirect_with_delay_slots_safe_p): New function.

From-SVN: r4968

diff --git a/gcc/reorg.c b/gcc/reorg.c
index 37307d9f172bdbca7734ce8747105f04c6e3bc21..5e96a1a84132f7d83658e6f7f97603762b4c6b96 100644 (file)
--- a/gcc/reorg.c
+++ b/gcc/reorg.c
@@ -1413,6 +1413,42 @@ condition_dominates_p (condition, insn)
 
   return comparison_dominates_p (code, other_code);
 }
+
+/* Return non-zero if redirecting JUMP to NEWLABEL does not invalidate
+   any insns already in the delay slot of JUMP.  */
+
+static int
+redirect_with_delay_slots_safe_p (jump, newlabel, seq)
+     rtx jump, newlabel, seq;
+{
+  int flags, slots, i;
+  rtx pat = PATTERN (seq);
+
+  /* Make sure all the delay slots of this jump would still
+     be valid after threading the jump.  If they are still
+     valid, then return non-zero.  */
+
+  flags = get_jump_flags (jump, newlabel);
+  for (i = 1; i < XVECLEN (pat, 0); i++)
+    if (! (
+#ifdef ANNUL_IFFALSE_SLOTS
+          (INSN_ANNULLED_BRANCH_P (jump)
+           && INSN_FROM_TARGET_P (XVECEXP (pat, 0, i)))
+          ? eligible_for_annul_false (jump, i - 1,
+                                      XVECEXP (pat, 0, i), flags) :
+#endif
+#ifdef ANNUL_IFTRUE_SLOTS
+          (INSN_ANNULLED_BRANCH_P (jump)
+           && ! INSN_FROM_TARGET_P (XVECEXP (pat, 0, i)))
+          ? eligible_for_annul_true (jump, i - 1,
+                                     XVECEXP (pat, 0, i), flags) :
+#endif
+          eligible_for_delay (jump, i -1, XVECEXP (pat, 0, i), flags)))
+      break;
+
+  return (i == XVECLEN (pat, 0));
+}
+
 \f
 /* INSN branches to an insn whose pattern SEQ is a SEQUENCE.  Given that
    the condition tested by INSN is CONDITION and the resources shown in
@@ -3647,7 +3683,8 @@ relax_delay_slots (first)
          if (trial == 0 && target_label != 0)
            trial = find_end_label ();
 
-         if (trial != target_label)
+         if (trial != target_label 
+             && redirect_with_delay_slots_safe_p (delay_insn, trial, insn))
            {
              reorg_redirect_jump (delay_insn, trial);
              target_label = trial;
@@ -3681,9 +3718,14 @@ relax_delay_slots (first)
              target_label = JUMP_LABEL (XVECEXP (PATTERN (trial), 0, 0));
              if (target_label == 0)
                target_label = find_end_label ();
-             reorg_redirect_jump (delay_insn, target_label);
-             next = insn;
-             continue;
+
+             if (redirect_with_delay_slots_safe_p (delay_insn, target_label, 
+                                                   insn))
+               {
+                 reorg_redirect_jump (delay_insn, target_label);
+                 next = insn;
+                 continue;
+               }
            }
        }
 
@@ -3752,20 +3794,24 @@ relax_delay_slots (first)
          if (label == 0)
            label = find_end_label ();
 
-         /* Be careful how we do this to avoid deleting code or labels
-            that are momentarily dead.  See similar optimization in jump.c  */
-         if (old_label)
-           ++LABEL_NUSES (old_label);
-
-         if (invert_jump (delay_insn, label))
+         if (redirect_with_delay_slots_safe_p (delay_insn, label, insn))
            {
-             delete_insn (next);
-             next = insn;
-           }
+             /* Be careful how we do this to avoid deleting code or labels
+                that are momentarily dead.  See similar optimization in
+                jump.c  */
+             if (old_label)
+               ++LABEL_NUSES (old_label);
 
-         if (old_label && --LABEL_NUSES (old_label) == 0)
-           delete_insn (old_label);
-         continue;
+             if (invert_jump (delay_insn, label))
+               {
+                 delete_insn (next);
+                 next = insn;
+               }
+
+             if (old_label && --LABEL_NUSES (old_label) == 0)
+               delete_insn (old_label);
+             continue;
+           }
        }
 
       /* If we own the thread opposite the way this insn branches, see if we