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Re: [PATCH][AArch64][2/3] Correct type attribute for mul and mneg instructions
- From: James Greenhalgh <james dot greenhalgh at arm dot com>
- To: Kyrill Tkachov <kyrylo dot tkachov at foss dot arm dot com>
- Cc: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, Marcus Shawcroft <Marcus dot Shawcroft at arm dot com>, Richard Earnshaw <Richard dot Earnshaw at arm dot com>, nd at arm dot com
- Date: Wed, 28 Nov 2018 16:37:38 +0000
- Subject: Re: [PATCH][AArch64][2/3] Correct type attribute for mul and mneg instructions
- References: <5BFC2F2B.3050102@foss.arm.com>
On Mon, Nov 26, 2018 at 11:36:43AM -0600, Kyrill Tkachov wrote:
> Hi all,
>
> In the AAarch64 ISA the MUL and MNEG instructions are actually aliases of MADD and MSUB.
> Therefore they should have the type attribute mla, rather than mul, which should only be used
> for AArch32 32-bit multiplication instructions.
>
> This will ensure more consistent scheduling decisions.
>
> Bootstrapped and tested on aarch64-none-linux-gnu.
>
> Ok for trunk?
OK in principle. Did you audit the pipeline models to check this doesn't
change scheduling class in an undesirable way for any of our supported
targets? OK if so, if not can you run that audit and figure out the right
thing to do to resolve it.
Thanks,
James