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

[Richard Henderson <rth@redhat.com>]

The following reply was made to PR optimization/8165; it has been noted by GNATS.

From: Richard Henderson <rth@redhat.com>
To: Glen Nakamura <glen@imodulo.com>
Cc: gcc-gnats@gcc.gnu.org, gcc-bugs@gcc.gnu.org, gcc-patches@gcc.gnu.org
Subject: Re: optimization/8165: builtin string functions SEGV on alpha-pc-linux-gnu at -O2
Date: Fri, 11 Oct 2002 15:44:48 -0700

 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;