* combine.c (recog_for_combine): Avoid allocating unnecesary RTX.

From-SVN: r76553

gcc/ChangeLog

+2004-01-25  Jan Hubicka  <jh@suse.cz>
+
+	* combine.c (recog_for_combine): Avoid allocating unnecesary RTX.
+
 2004-01-25  Richard Sandiford  <rsandifo@redhat.com>
 
 	* config/mips/mips-protos.h (mips_reg_mode_ok_for_base_p): Delete.

gcc/combine.c

@@ -9869,7 +9869,7 @@ recog_for_combine (rtx *pnewpat, rtx insn, rtx *pnotes)
   int num_clobbers_to_add = 0;
   int i;
   rtx notes = 0;
-  rtx dummy_insn;
+  rtx old_notes, old_pat;
 
   /* If PAT is a PARALLEL, check to see if it contains the CLOBBER
      we use to indicate that something didn't match.  If we find such a
@@ -9880,13 +9880,12 @@ recog_for_combine (rtx *pnewpat, rtx insn, rtx *pnotes)
 	  && XEXP (XVECEXP (pat, 0, i), 0) == const0_rtx)
 	return -1;
 
-  /* *pnewpat does not have to be actual PATTERN (insn), so make a dummy
-     instruction for pattern recognition.  */
-  dummy_insn = shallow_copy_rtx (insn);
-  PATTERN (dummy_insn) = pat;
-  REG_NOTES (dummy_insn) = 0;
+  old_pat = PATTERN (insn);
+  old_notes = REG_NOTES (insn);
+  PATTERN (insn) = pat;
+  REG_NOTES (insn) = 0;
 
-  insn_code_number = recog (pat, dummy_insn, &num_clobbers_to_add);
+  insn_code_number = recog (pat, insn, &num_clobbers_to_add);
 
   /* If it isn't, there is the possibility that we previously had an insn
      that clobbered some register as a side effect, but the combined
@@ -9911,9 +9910,11 @@ recog_for_combine (rtx *pnewpat, rtx insn, rtx *pnotes)
       if (pos == 1)
 	pat = XVECEXP (pat, 0, 0);
 
-      PATTERN (dummy_insn) = pat;
-      insn_code_number = recog (pat, dummy_insn, &num_clobbers_to_add);
+      PATTERN (insn) = pat;
+      insn_code_number = recog (pat, insn, &num_clobbers_to_add);
     }
+  PATTERN (insn) = old_pat;
+  REG_NOTES (insn) = old_notes;
 
   /* Recognize all noop sets, these will be killed by followup pass.  */
   if (insn_code_number < 0 && GET_CODE (pat) == SET && set_noop_p (pat))