Re: [PATCH v9 4/4] ree: Improve ree pass for rs6000 target using defined ABI interfaces

[Ajit Agarwal <aagarwa1@linux.ibm.com>]

Hello All:

Addressed below review comments in the version 11 of the patch.
Please review and please let me know if its ok for trunk.

Thanks & Regards
Ajit

On 22/10/23 12:56 am, rep.dot.nop@gmail.com wrote:
> On 21 October 2023 01:56:16 CEST, Vineet Gupta <vineetg@rivosinc.com> wrote:
>> On 10/19/23 23:50, Ajit Agarwal wrote:
>>> Hello All:
>>>
>>> This version 9 of the patch uses abi interfaces to remove zero and sign extension elimination.
>>> Bootstrapped and regtested on powerpc-linux-gnu.
>>>
>>> In this version (version 9) of the patch following review comments are incorporated.
>>>
>>> a) Removal of hard code zero_extend and sign_extend  in abi interfaces.
>>> b) Source and destination with different registers are considered.
>>> c) Further enhancements.
>>> d) Added sign extension elimination using abi interfaces.
>>
>> As has been trend in the past, I don't think all the review comments have been addressed.
> 
> And apart from that, may I ask if this is just me, or does anybody else think that it might be worthwhile to actually read a patch before (re-)posting?
> 
> Seeing e.g. the proposed abi_extension_candidate_p as written in a first POC would deserve some manual CSE, if nothing more then for clarity and conciseness?
> 
> Just curious from a meta perspective..
> 
> And:
> 
>>> ree: Improve ree pass for rs6000 target using defined abi interfaces
> 
> mentioning powerpc like this, and then changing generic code could be interpreted as misleading, IMHO.
> 
>>>
>>> For rs6000 target we see redundant zero and sign extension and done
>>> to improve ree pass to eliminate such redundant zero and sign extension
>>> using defined ABI interfaces.
> 
> Mentioning powerpc in the body as one of the affected target(s) is of course fine.
> 
> 
>>>   +/* Return TRUE if target mode is equal to source mode of zero_extend
>>> +   or sign_extend otherwise false.  */
> 
> , false otherwise.
> 
> But I'm not a native speaker 
> 
> 
>>> +/* Return TRUE if the candidate insn is zero extend and regno is
>>> +   a return registers.  */
>>> +
>>> +static bool
>>> +abi_extension_candidate_return_reg_p (/*rtx_insn *insn, */int regno)
> 
> Leftover debug comment.
> 
>>> +{
>>> +  if (targetm.calls.function_value_regno_p (regno))
>>> +    return true;
>>> +
>>> +  return false;
>>> +}
>>> +
> 
> As said, I don't see why the below was not cleaned up before the V1 submission.
> Iff it breaks when manually CSEing, I'm curious why?
> 
>>> +/* Return TRUE if reg source operand of zero_extend is argument registers
>>> +   and not return registers and source and destination operand are same
>>> +   and mode of source and destination operand are not same.  */
>>> +
>>> +static bool
>>> +abi_extension_candidate_p (rtx_insn *insn)
>>> +{
>>> +  rtx set = single_set (insn);
>>> +  machine_mode dst_mode = GET_MODE (SET_DEST (set));
>>> +  rtx orig_src = XEXP (SET_SRC (set), 0);
>>> +
>>> +  if (!FUNCTION_ARG_REGNO_P (REGNO (orig_src))
>>> +      || abi_extension_candidate_return_reg_p (/*insn,*/ REGNO (orig_src)))
> 
> On top, debug leftover.
> 
>>> +    return false;
>>> +
>>> +  /* Mode of destination and source should be different.  */
>>> +  if (dst_mode == GET_MODE (orig_src))
>>> +    return false;
>>> +
>>> +  machine_mode mode = GET_MODE (XEXP (SET_SRC (set), 0));
>>> +  bool promote_p = abi_target_promote_function_mode (mode);
>>> +
>>> +  /* REGNO of source and destination should be same if not
>>> +      promoted.  */
>>> +  if (!promote_p && REGNO (SET_DEST (set)) != REGNO (orig_src))
>>> +    return false;
>>> +
>>> +  return true;
>>> +}
>>> +
> 
> As said, please also rephrase the above (and everything else if it obviously looks akin the above).
> 
> The rest, mentioned below,  should largely be covered by following the coding convention.
> 
>>> +/* Return TRUE if the candidate insn is zero extend and regno is
>>> +   an argument registers.  */
> 
> Singular register.
> 
>>> +
>>> +static bool
>>> +abi_extension_candidate_argno_p (/*rtx_code code, */int regno)
> 
> Debug leftover.
> I would probably have inlined this function manually, with a respective comment.
> Did not look how often it is used, admittedly.
> 
>>> +{
>>> +  if (FUNCTION_ARG_REGNO_P (regno))
>>> +    return true;
>>> +
>>> +  return false;
>>> +}
> []
>>> +
>>>   /* This function goes through all reaching defs of the source
> 
> s/This function goes/Go/
> 
>>>      of the candidate for elimination (CAND) and tries to combine
> 
> (of, ?didn't look) candidate CAND for eliminating
> 
>>>      the extension with the definition instruction.  The changes
> 
> defining
> 
> Pre-existing, I know.
> But you could fix those in a preparatory patch while you touch surrounding code.
> This is not a requirement, of course, just good habit, IMHO.
> 
>>> @@ -770,6 +889,11 @@ combine_reaching_defs (ext_cand *cand, const_rtx set_pat, ext_state *state)
>>>       state->defs_list.truncate (0);
>>>     state->copies_list.truncate (0);
>>> +  rtx orig_src = XEXP (SET_SRC (cand->expr),0);
>>> +
>>> +  if (abi_extension_candidate_p (cand->insn)
>>> +      && (!get_defs (cand->insn, orig_src, NULL)))
> 
> Excess braces.
> Hopefully check_gnu_style would have complained.
> 
>>> +    return abi_handle_regs (cand->insn);
>>>       outcome = make_defs_and_copies_lists (cand->insn, set_pat, state);
>>>   @@ -1036,6 +1160,15 @@ combine_reaching_defs (ext_cand *cand, const_rtx set_pat, ext_state *state)
>>>           }
>>>       }
>>>   +  rtx insn_set = single_set (cand->insn);
>>> +
>>> +  machine_mode mode = (GET_MODE (XEXP (SET_SRC (insn_set), 0)));
> 
> Excess braces.
> Also in a lot of other spots in your patch.
> Please read the coding conventions and the patch, once again, before submission?
> thanks