RE: [PATCH v3] Machine_Mode: Extend machine_mode from 8 to 16 bits

["Li, Pan2" <pan2.li@intel.com>]

Thanks Richard Sandiford for review.

Yes, currently the class access_info will be extended from 8 bytes to 12 bytes, which is missed in the table. With the adjustment as you suggested it will be 8 bytes but unfortunately the change of m_kind may trigger some ICE in some test case(s).

I will take a look into it and keep you posted.

Pan

-----Original Message-----
From: Richard Sandiford <richard.sandiford@arm.com> 
Sent: Tuesday, May 16, 2023 5:09 PM
To: Li, Pan2 <pan2.li@intel.com>
Cc: gcc-patches@gcc.gnu.org; juzhe.zhong@rivai.ai; kito.cheng@sifive.com; Wang, Yanzhang <yanzhang.wang@intel.com>; jeffreyalaw@gmail.com; rguenther@suse.de
Subject: Re: [PATCH v3] Machine_Mode: Extend machine_mode from 8 to 16 bits

pan2.li@intel.com writes:
> diff --git a/gcc/rtl-ssa/accesses.h b/gcc/rtl-ssa/accesses.h index 
> c5180b9308a..38b4d6160c2 100644
> --- a/gcc/rtl-ssa/accesses.h
> +++ b/gcc/rtl-ssa/accesses.h
> @@ -254,7 +254,7 @@ private:
>    unsigned int m_spare : 2;
>  
>    // The value returned by the accessor above.
> -  machine_mode m_mode : 8;
> +  machine_mode m_mode : MACHINE_MODE_BITSIZE;
>  };
>  
>  // A contiguous array of access_info pointers.  Used to represent a

This structure (access_info) isn't mentioned in the table in the patch description.  The structure is currently 1 LP64 word and is very size-sensitive.  I think we should:

- Put the mode after m_regno
- Reduce m_kind to 2 bits
- Remove m_spare

I *think* that will keep the current size, but please check.

LGTM otherwise.

Thanks,
Richard