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Re: [PATCH][gas][arm] Add -mwarn-restrict-it
- From: Wilco Dijkstra <Wilco dot Dijkstra at arm dot com>
- To: Christophe Lyon <christophe dot lyon at linaro dot org>
- Cc: "binutils at sourceware dot org" <binutils at sourceware dot org>
- Date: Mon, 9 Dec 2019 10:19:12 +0000
- Subject: Re: [PATCH][gas][arm] Add -mwarn-restrict-it
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Hi Christophe,
> So default effect of this patch is that the warning will not be
> emitted anymore, unless the user requests it explicitly.
Exactly, most people just find it annoying.
> What is the actual performance impact of these instructions? I mean:
> with your patch most people won't be aware of a possible future
> problem with their code.
Well you get much better performance when you use these instructions
(https://gcc.gnu.org/ml/gcc-patches/2019-11/msg00399.html).
I don't believe it's the assembler's job to warn about potentially slow code.
Cheers,
Wilco