[PATCH] Fix recog_for_combine (was Re: [testcase] -fssa -fssa-ccp -march=i686 ICE)

[Jakub Jelinek <jakub at redhat dot com>]

On Fri, Feb 01, 2002 at 03:42:43PM -0800, Richard Henderson wrote:
> On Sat, Feb 02, 2002 at 12:38:22AM +0100, Jakub Jelinek wrote:
> > or recog_for_combine needs to temporarily modify the instruction by
> > setting its pattern to pat and back or, if modifying insn is not an
> > option, making a dummy insn with PATTERN pat and reg notes copied over).
> > What do you think?
> 
> Using a dummy insn would eliminate the old_notes frobbing too,
> so that would seem the best way.

Here it is, bootstrapped on i386-redhat-linux, no regressions.
Ok to commit?

2002-02-02  Jakub Jelinek  <jakub@redhat.com>

	* combine.c (recog_for_combine): Create a dummy insn with PATTERN
	pat for recog.

	* gcc.dg/20020201-4.c: New test.

--- gcc/combine.c.jj	Wed Jan 23 16:29:00 2002
+++ gcc/combine.c	Sat Feb  2 12:07:13 2002
@@ -9590,7 +9590,7 @@ recog_for_combine (pnewpat, insn, pnotes
   int num_clobbers_to_add = 0;
   int i;
   rtx notes = 0;
-  rtx old_notes;
+  rtx dummy_insn;
 
   /* 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
@@ -9601,11 +9601,13 @@ recog_for_combine (pnewpat, insn, pnotes
 	  && XEXP (XVECEXP (pat, 0, i), 0) == const0_rtx)
 	return -1;
 
-  /* Remove the old notes prior to trying to recognize the new pattern.  */
-  old_notes = REG_NOTES (insn);
-  REG_NOTES (insn) = 0;
+  /* *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;
 
-  insn_code_number = recog (pat, insn, &num_clobbers_to_add);
+  insn_code_number = recog (pat, dummy_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
@@ -9630,15 +9632,14 @@ recog_for_combine (pnewpat, insn, pnotes
       if (pos == 1)
 	pat = XVECEXP (pat, 0, 0);
 
-      insn_code_number = recog (pat, insn, &num_clobbers_to_add);
+      PATTERN (dummy_insn) = pat;
+      insn_code_number = recog (pat, dummy_insn, &num_clobbers_to_add);
     }
 
   /* Recognize all noop sets, these will be killed by followup pass.  */
   if (insn_code_number < 0 && GET_CODE (pat) == SET && set_noop_p (pat))
     insn_code_number = NOOP_MOVE_INSN_CODE, num_clobbers_to_add = 0;
 
-  REG_NOTES (insn) = old_notes;
-
   /* If we had any clobbers to add, make a new pattern than contains
      them.  Then check to make sure that all of them are dead.  */
   if (num_clobbers_to_add)
--- gcc/testsuite/gcc.dg/20020201-4.c.jj	Sat Feb  2 12:24:00 2002
+++ gcc/testsuite/gcc.dg/20020201-4.c	Sat Feb  2 23:19:55 2002
@@ -0,0 +1,16 @@
+/* This testcase failed because recog_for_combine used to pass a different
+   pattern than contained in insn to recog.  */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fssa -fssa-ccp" } */
+/* { dg-options "-O2 -march=i686 -fssa -fssa-ccp" { target i?86-*-* } } */
+
+extern int bar (char *);
+
+int
+foo (void)
+{
+  char b[512];
+
+  bar (b);
+  return __builtin_strlen (b);
+}

	Jakub