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Re: [PATCH 01/10] rs6000: Clobber XER[CA] in all user asm statements
- From: David Edelsohn <dje dot gcc at gmail dot com>
- To: Segher Boessenkool <segher at kernel dot crashing dot org>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 8 Dec 2014 09:25:34 -0500
- Subject: Re: [PATCH 01/10] rs6000: Clobber XER[CA] in all user asm statements
- Authentication-results: sourceware.org; auth=none
- References: <cover dot 1418024189 dot git dot segher at kernel dot crashing dot org> <7a4b7bd73211032ecf856de06a20e14a323e08ba dot 1418024189 dot git dot segher at kernel dot crashing dot org>
On Mon, Dec 8, 2014 at 9:18 AM, Segher Boessenkool
<segher@kernel.crashing.org> wrote:
> A lot of old user code clobbers the carry bit without telling the compiler
> about it. This used to just work, because the compiler never used the bit
> outside of a single RTL instruction. But that will change. Let's clobber
> the carry bit in every asm; this isn't very expensive.
>
>
> 2014-12-08 Segher Boessenkool <segher@kernel.crashing.org>
>
> gcc/
> PR target/64180
> * config/rs6000/rs6000.c (TARGET_MD_ASM_CLOBBERS): Define.
> (rs6000_md_asm_clobbers): New function.
Okay. I don't know of another option that preserves backward
compatibility. If RTH looks at this series of patches, he may have a
better suggestion.
Thanks, David