[rtl] PR middle-end/78016, keep REG_NOTE order during insn copy

On 10/21/2016 02:04 PM, Jiong Wang wrote:
> +  /* Locate the end of existing REG_NOTES in NEW_RTX.  */
> +  rtx *ptail = &REG_NOTES (new_rtx);
> +  while (*ptail != NULL_RTX)
> +    ptail = &XEXP (*ptail, 1);

I was thinking along the lines of something like this (untested, 
emit-rtl.c part omitted). Eric can choose whether he likes either of 
these or wants something else.


Bernd

On 21/10/16 13:30, Bernd Schmidt wrote:
>
>
> On 10/21/2016 02:04 PM, Jiong Wang wrote:
>> +  /* Locate the end of existing REG_NOTES in NEW_RTX.  */
>> +  rtx *ptail = &REG_NOTES (new_rtx);
>> +  while (*ptail != NULL_RTX)
>> +    ptail = &XEXP (*ptail, 1);
>
> I was thinking along the lines of something like this (untested, 
> emit-rtl.c part omitted). Eric can choose whether he likes either of 
> these or wants something else.

Hi Eric,

   What's your decision on this?

   Thanks.

Regards,
Jiong

>
>
> Bernd
>
> Index: gcc/rtl.h
> ===================================================================
> --- gcc/rtl.h    (revision 241233)
> +++ gcc/rtl.h    (working copy)
> @@ -3008,6 +3008,7 @@ extern rtx alloc_reg_note (enum reg_note
>  extern void add_reg_note (rtx, enum reg_note, rtx);
>  extern void add_int_reg_note (rtx, enum reg_note, int);
>  extern void add_shallow_copy_of_reg_note (rtx_insn *, rtx);
> +extern rtx duplicate_reg_note (rtx_insn *, rtx);
>  extern void remove_note (rtx, const_rtx);
>  extern void remove_reg_equal_equiv_notes (rtx_insn *);
>  extern void remove_reg_equal_equiv_notes_for_regno (unsigned int);
> Index: gcc/rtlanal.c
> ===================================================================
> --- gcc/rtlanal.c    (revision 241233)
> +++ gcc/rtlanal.c    (working copy)
> @@ -2304,6 +2304,21 @@ add_shallow_copy_of_reg_note (rtx_insn *
>      add_reg_note (insn, REG_NOTE_KIND (note), XEXP (note, 0));
>  }
>
> +/* Duplicate NOTE and return the copy.  */
> +rtx
> +duplicate_reg_note (rtx note)
> +{
> +  rtx n;
> +  reg_note_kind kind = REG_NOTE_KIND (note);
> +
> +  if (GET_CODE (note) == INT_LIST)
> +    return gen_rtx_INT_LIST ((machine_mode) kind, XINT (note, 0), 
> NULL_RTX);
> +  else if (GET_CODE (note) == EXPR_LIST)
> +    return alloc_reg_note (kind, copy_insn_1 (XEXP (note, 0)), 
> NULL_RTX);
> +  else
> +    return alloc_reg_note (kind, XEXP (note, 0), NULL_RTX);
> +}
> +
>  /* Remove register note NOTE from the REG_NOTES of INSN.  */
>
>  void
> Index: gcc/sel-sched-ir.c
> ===================================================================
> --- gcc/sel-sched-ir.c    (revision 241233)
> +++ gcc/sel-sched-ir.c    (working copy)
> @@ -5762,6 +5762,11 @@ create_copy_of_insn_rtx (rtx insn_rtx)
>    res = create_insn_rtx_from_pattern (copy_rtx (PATTERN (insn_rtx)),
>                                        NULL_RTX);
>
> +  /* Locate the end of existing REG_NOTES in NEW_RTX.  */
> +  rtx *ptail = &REG_NOTES (new_rtx);
> +  while (*ptail != NULL_RTX)
> +    ptail = &XEXP (*ptail, 1);
> +
>    /* Copy all REG_NOTES except REG_EQUAL/REG_EQUIV and REG_LABEL_OPERAND
>       since mark_jump_label will make them.  REG_LABEL_TARGETs are 
> created
>       there too, but are supposed to be sticky, so we copy them. */
> @@ -5770,11 +5775,8 @@ create_copy_of_insn_rtx (rtx insn_rtx)
>      && REG_NOTE_KIND (link) != REG_EQUAL
>      && REG_NOTE_KIND (link) != REG_EQUIV)
>        {
> -    if (GET_CODE (link) == EXPR_LIST)
> -      add_reg_note (res, REG_NOTE_KIND (link),
> -            copy_insn_1 (XEXP (link, 0)));
> -    else
> -      add_reg_note (res, REG_NOTE_KIND (link), XEXP (link, 0));
> +    *ptail = duplicate_reg_note (link);
> +    ptail = &XEXP (*ptail, 1);
>        }
>
>    return res;

>    What's your decision on this?

I think that we ought to standardize on a single order for note copying in the 
RTL middle-end and the best way to enforce it is to have a single primitive in 
rtlanal.c, with an optional filtering.  Bernd's patch is a step in the right 
direction, but doesn't enforce the single order.  Maybe something based on a 
macro calling duplicate_reg_note, but not clear whether it's really better.

On 03/11/16 12:06, Eric Botcazou wrote:
>>     What's your decision on this?
> I think that we ought to standardize on a single order for note copying in the
> RTL middle-end and the best way to enforce it is to have a single primitive in
> rtlanal.c, with an optional filtering.  Bernd's patch is a step in the right
> direction, but doesn't enforce the single order.  Maybe something based on a
> macro calling duplicate_reg_note, but not clear whether it's really better.

Thanks for the feedback,  I'll try to work through this.

Regards,
Jiong

> Thanks for the feedback,  I'll try to work through this.

Thanks, but since there doesn't seem to be a consensus on the goal, feel free 
to disregard it and just implement what you need for your initial work.