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

[rep.dot.nop@gmail.com]

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