Re: optimization/8165: builtin string functions SEGV on alpha-pc-linux-gnu at -O2

[Richard Henderson <rth at redhat dot com>]

You're right about the REG_EQUAL note being bogus, but as I feared,
the fix was in the wrong place.  The problem has nothing to do with
lo_sum in specific, but is a generic issue with local cprop failing
to update notes.

Addressed thus.


r~


        * gcse.c (adjust_libcall_notes): Also adjust notes for INSN.

Index: gcse.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/gcse.c,v
retrieving revision 1.220
diff -u -p -r1.220 gcse.c
--- gcse.c	30 Sep 2002 13:00:29 -0000	1.220
+++ gcse.c	11 Oct 2002 07:51:06 -0000
@@ -4251,6 +4251,7 @@ cprop_insn (insn, alter_jumps)
 
 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
    their REG_EQUAL notes need updating.  */
+
 static bool
 do_local_cprop (x, insn, alter_jumps, libcall_sp)
      rtx x;
@@ -4260,10 +4261,12 @@ do_local_cprop (x, insn, alter_jumps, li
 {
   rtx newreg = NULL, newcnst = NULL;
 
-  /* Rule out USE instructions and ASM statements as we don't want to change the hard registers mentioned.  */
+  /* Rule out USE instructions and ASM statements as we don't want to
+     change the hard registers mentioned.  */
   if (GET_CODE (x) == REG
       && (REGNO (x) >= FIRST_PSEUDO_REGISTER
-          || (GET_CODE (PATTERN (insn)) != USE && asm_noperands (PATTERN (insn)) < 0)))
+          || (GET_CODE (PATTERN (insn)) != USE
+	      && asm_noperands (PATTERN (insn)) < 0)))
     {
       cselib_val *val = cselib_lookup (x, GET_MODE (x), 0);
       struct elt_loc_list *l;
@@ -4327,17 +4330,23 @@ do_local_cprop (x, insn, alter_jumps, li
 
 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
    their REG_EQUAL notes need updating to reflect that OLDREG has been
-   replaced with NEWVAL in INSN.  Return true if all substitutions could
-   be made.  */
+   replaced with NEWVAL in INSN.  Also update the REG_EQUAL notes in INSN.
+
+   Return true if all substitutions could be made.  */
+
 static bool
 adjust_libcall_notes (oldreg, newval, insn, libcall_sp)
      rtx oldreg, newval, insn, *libcall_sp;
 {
-  rtx end;
+  rtx end, note;
+
+  note = find_reg_equal_equiv_note (insn);
+  if (note)
+    XEXP (note, 0) = replace_rtx (XEXP (note, 0), oldreg, newval);
 
   while ((end = *libcall_sp++))
     {
-      rtx note = find_reg_equal_equiv_note (end);
+      note = find_reg_equal_equiv_note (end);
 
       if (! note)
 	continue;