This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.

Index Nav:	[Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav:	[Date Prev] [Date Next]	[Thread Prev] [Thread Next]
Other format:	[Raw text]

Re: [PATCH 3/3] Avoid emitting useless instructions in mips_process_sync_loop.

From: Richard Sandiford <rdsandiford at googlemail dot com>
To: Maxim Kuvyrkov <maxim at codesourcery dot com>
Cc: Tom de Vries <vries at codesourcery dot com>, gcc-patches Patches <gcc-patches at gcc dot gnu dot org>
Date: Wed, 13 Jun 2012 19:59:29 +0100
Subject: Re: [PATCH 3/3] Avoid emitting useless instructions in mips_process_sync_loop.
References: <6BB30BFE-2322-45D3-A898-FBD3FEDE84D2@codesourcery.com> <46A88854-A8B2-49F7-BAF0-DED0A78E8EF6@codesourcery.com>

Maxim Kuvyrkov <maxim@codesourcery.com> writes:
> +  /* Don't bother setting returns that are never used.  */
> +  if (cmp && find_reg_note (insn, REG_UNUSED, cmp))
> +    cmp = 0;
> +  if (required_oldval && find_reg_note (insn, REG_UNUSED, required_oldval))
> +    required_oldval = 0;

required_oldval is an important input (not output).  We can't drop it.
I suppose we could replace oldval with AT if the non-AT register isn't used,
but I'm not sure it's worth it.

The CMP part is OK though.

Richard

Follow-Ups:
- Re: [PATCH 3/3] Avoid emitting useless instructions in mips_process_sync_loop.
  - From: Maxim Kuvyrkov

References:
- [PATCH, MIPS] Add most common atomic patterns
  - From: Maxim Kuvyrkov
- [PATCH 3/3] Avoid emitting useless instructions in mips_process_sync_loop.
  - From: Maxim Kuvyrkov

Index Nav:	[Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav:	[Date Prev] [Date Next]	[Thread Prev] [Thread Next]