eliminate_regs_in_insn): Handle special case of assignment from hard frame...

eliminate_regs_in_insn): Handle special case of assignment from hard
frame pointer to frame pointer (for nonlocal goto).

From-SVN: r7696

diff --git a/gcc/reload1.c b/gcc/reload1.c
index 360dc89238944ba8153f21dce0e67d44c4db5f13..e46d76421a8a2218095f5375a65063e228f2fa35 100644 (file)
--- a/gcc/reload1.c
+++ b/gcc/reload1.c
@@ -3144,6 +3144,50 @@ eliminate_regs_in_insn (insn, replace)
       for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
        if (ep->from_rtx == SET_DEST (old_set) && ep->can_eliminate)
          {
+#if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
+           /* If this is setting the frame pointer register to the
+              hardware frame pointer register and this is an elimination
+              that will be done (tested above), this insn is really
+              adjusting the frame pointer downward to compensate for
+              the adjustment done before a nonlocal goto.  */
+           if (ep->from == FRAME_POINTER_REGNUM
+               && ep->to == HARD_FRAME_POINTER_REGNUM)
+             {
+               rtx src = SET_SRC (old_set);
+               int offset, ok = 0;
+
+               if (src == ep->to_rtx)
+                 offset = 0, ok = 1;
+               else if (GET_CODE (src) == PLUS
+                        && GET_CODE (XEXP (src, 0)) == CONST_INT)
+                 offset = INTVAL (XEXP (src, 0)), ok = 1;
+
+               if (ok)
+                 {
+                   if (replace)
+                     {
+                       rtx src
+                         = plus_constant (ep->to_rtx, offset - ep->offset);
+
+                       /* First see if this insn remains valid when we
+                          make the change.  If not, keep the INSN_CODE
+                          the same and let reload fit it up.  */
+                       validate_change (insn, &SET_SRC (old_set), src, 1);
+                       validate_change (insn, &SET_DEST (old_set),
+                                        ep->to_rtx, 1);
+                       if (! apply_change_group ())
+                         {
+                           SET_SRC (old_set) = src;
+                           SET_DEST (old_set) = ep->to_rtx;
+                         }
+                     }
+
+                   val = 1;
+                   goto done;
+                 }
+             }
+#endif
+
            /* In this case this insn isn't serving a useful purpose.  We
               will delete it in reload_as_needed once we know that this
               elimination is, in fact, being done.