[Bug target/32437] [4.3 Regression] MIPS: FAIL in gcc.dg/cleanup-[8|9|10|11].c

["zadeck at naturalbridge dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #20 from zadeck at naturalbridge dot com  2007-06-27 14:39 -------
Subject: Re:  [4.3 Regression] MIPS: FAIL in gcc.dg/cleanup-[8|9|10|11].c

richard at codesourcery dot com wrote:
> ------- Comment #19 from richard at codesourcery dot com  2007-06-27 14:37 -------
> Subject: Re:  [4.3 Regression] MIPS: FAIL in gcc.dg/cleanup-[8|9|10|11].c
>
> Kenneth Zadeck <zadeck@naturalbridge.com> writes:
>   
>> 2007-06-23  Kenneth Zadeck <zadeck@naturalbridge.com>
>>
>>     PR middle-end/32437
>>     *dce.c (deletable_insn_p): Add extra parameter and recurse if insn
>>     is a PARALLEL.
>>     (prescan_insns_for_dce): Add extra parameter.
>>     
>
> Kenny found that this patch introduced problems on x86 (I think it was)
> because it applied the special handling for bare CLOBBERs to those
> inside PARALLELs as well.  We don't want that; bare USEs and CLOBBERs
> are special DF markers, but USEs and CLOBBERs inside PARALLELs are parts
> of asms or define_insns.
>
> Kenny pre-approved the patch below.  Bootstrapped & regression-tested
> on x86_64-linux-gnu.  Applied to mainline.
>
> Richard
>
>
> gcc/
>         * dce.c (deletable_insn_p_1): New function, split out from...
>         (deletable_insn_p): ...here.  Only treat bare USEs and CLOBBERs
>         specially, not those inside PARALLELs.  Remove BODY argument
>         and adjust recursive call accordingly.
>         (prescan_insns_for_dce): Update call to delete_insn_p.
>
> Index: gcc/dce.c
> ===================================================================
> --- gcc/dce.c   (revision 126053)
> +++ gcc/dce.c   (working copy)
> @@ -58,16 +58,15 @@ static VEC(rtx,heap) *worklist;
>
>  static sbitmap marked = NULL;
>
> -/* Return true if INSN with BODY is a normal instruction that can be
> -   deleted by the DCE pass.  */
> +/* A subroutine for which BODY is part of the instruction being tested;
> +   either the top-level pattern, or an element of a PARALLEL.  The
> +   instruction is known not to be a bare USE or CLOBBER.  */
>
>  static bool
> -deletable_insn_p (rtx insn, rtx body, bool fast)
> +deletable_insn_p_1 (rtx body)
>  {
> -  rtx x;
>    switch (GET_CODE (body))
>      {
> -    case USE:
>      case PREFETCH:
>      case TRAP_IF:
>        /* The UNSPEC case was added here because the ia-64 claims that
> @@ -79,6 +78,35 @@ deletable_insn_p (rtx insn, rtx body, bo
>      case UNSPEC:
>        return false;
>
> +    default:
> +      if (volatile_insn_p (body))
> +       return false;
> +
> +      if (flag_non_call_exceptions && may_trap_p (body))
> +       return false;
> +
> +      return true;
> +    }
> +}
> +
> +/* Return true if INSN is a normal instruction that can be deleted by
> +   the DCE pass.  */
> +
> +static bool
> +deletable_insn_p (rtx insn, bool fast)
> +{
> +  rtx body, x;
> +  int i;
> +
> +  if (!NONJUMP_INSN_P (insn))
> +    return false;
> +
> +  body = PATTERN (insn);
> +  switch (GET_CODE (body))
> +    {
> +    case USE:
> +      return false;
> +
>      case CLOBBER:
>        if (fast)
>         {
> @@ -88,32 +116,20 @@ deletable_insn_p (rtx insn, rtx body, bo
>           x = XEXP (body, 0);
>           return REG_P (x) && (!HARD_REGISTER_P (x) || reload_completed);
>         }
> -      else 
> +      else
>         /* Because of the way that use-def chains are built, it is not
>            possible to tell if the clobber is dead because it can
>            never be the target of a use-def chain.  */
>         return false;
>
>      case PARALLEL:
> -      {
> -       int i;
> -       for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
> -         if (!deletable_insn_p (insn, XVECEXP (body, 0, i), fast))
> -           return false;
> -       return true;
> -      }
> +      for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
> +       if (!deletable_insn_p_1 (XVECEXP (body, 0, i)))
> +         return false;
> +      return true;
>
>      default:
> -      if (!NONJUMP_INSN_P (insn))
> -       return false;
> -
> -      if (volatile_insn_p (body))
> -       return false;
> -
> -      if (flag_non_call_exceptions && may_trap_p (body))
> -       return false;
> -
> -      return true;
> +      return deletable_insn_p_1 (body);
>      }
>  }
>
> @@ -369,7 +385,7 @@ prescan_insns_for_dce (bool fast)
>          rtx note = find_reg_note (insn, REG_LIBCALL_ID, NULL_RTX);
>          if (note)
>            mark_libcall (insn, fast);
> -        else if (deletable_insn_p (insn, PATTERN (insn), fast))
> +        else if (deletable_insn_p (insn, fast))
>            mark_nonreg_stores (PATTERN (insn), insn, fast);
>          else
>            mark_insn (insn, fast);
>
>
>   
thanks


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32437