Re: [PATCH 2/4] [RISC-V] support cm.popretz in zcmp

[Kito Cheng <kito.cheng@gmail.com>]

I was thinking does it possible to using peephole2 to optimize this
case, but I realized their is several barrier, like stack tie and
note...so it seems hard to just leverage peephole2.

And the patch is LGTM, only a few minor coding format issues, but you
don't need to send new patch, I can fix those stuff when I push, and I
would strongly suggest you setup git-format-patch, <gcc-src>/contrib
has a clang format setting , that can release you from the boring
coding format issues.

# Copy to <gcc-src>/.clang-format, so that clang-format can found that
automatically.
$ cp contrib/clang-format .clang-format


> @@ -5747,6 +5748,80 @@ riscv_adjust_libcall_cfi_epilogue ()
>    return dwarf;
>  }
>
> +/* return true if popretz pattern can be matched.
> +   set (reg 10 a0) (const_int 0)
> +   use (reg 10 a0)
> +   NOTE_INSN_EPILOGUE_BEG  */
> +static rtx_insn *
> +riscv_zcmp_can_use_popretz(void)

Need space between function name and (void)

> +{
> +  rtx_insn *insn = NULL, *use = NULL, *clear = NULL;
> +
> +  /* sequence stack for NOTE_INSN_EPILOGUE_BEG*/
> +  struct sequence_stack * outer_seq = get_current_sequence ()->next;
> +  if (!outer_seq)
> +    return NULL;
> +  insn = outer_seq->first;
> +  if(!insn || !NOTE_P (insn) || NOTE_KIND (insn) != NOTE_INSN_EPILOGUE_BEG)
> +    return NULL;
> +
> +  /* sequence stack for the insn before NOTE_INSN_EPILOGUE_BEG*/
> +  outer_seq = outer_seq->next;
> +  if (outer_seq)
> +    insn = outer_seq->last;
> +
> +  /* skip notes  */
> +  while (insn && NOTE_P (insn))
> +    {
> +      insn = PREV_INSN (insn);
> +    }
> +  use = insn;
> +
> +  /* match use (reg 10 a0)  */
> +  if (use == NULL || !INSN_P (use)
> +      || GET_CODE (PATTERN (use)) != USE
> +      || !REG_P(XEXP(PATTERN (use), 0))
> +      || REGNO(XEXP(PATTERN (use), 0)) != A0_REGNUM)
> +    return NULL;
> +
> +  /* match set (reg 10 a0) (const_int 0 [0])  */
> +  clear = PREV_INSN (use);
> +  if (clear != NULL && INSN_P (clear)
> +      && GET_CODE (PATTERN (clear)) == SET
> +      && REG_P (SET_DEST (PATTERN (clear)))
> +      && REGNO (SET_DEST (PATTERN (clear))) == A0_REGNUM
> +      && SET_SRC (PATTERN (clear)) == const0_rtx)
> +    return clear;
> +
> +  return NULL;
> +}
> +
> +static void
> +riscv_gen_multi_pop_insn(bool use_multi_pop_normal, unsigned mask,
> +                         unsigned multipop_size)

Same issue here, need space between argument and function name.