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Re: basic asm and memory clobbers
- From: Andrew Haley <aph at redhat dot com>
- To: David Wohlferd <dw at LimeGreenSocks dot com>, Richard Henderson <rth at redhat dot com>, Jakub Jelinek <jakub at redhat dot com>
- Cc: Segher Boessenkool <segher at kernel dot crashing dot org>, Jeff Law <law at redhat dot com>, "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>, rth at gcc dot gnu dot org, pinskia at gcc dot gnu dot org, Sandra Loosemore <sandra at codesourcery dot com>
- Date: Mon, 23 Nov 2015 10:04:22 +0000
- Subject: Re: basic asm and memory clobbers
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On 21/11/15 12:56, David Wohlferd wrote:
> So, what now?
>
> While I'd like to take the big step and start kicking out warnings for
> non-top-level right now, that may be too bold for phase 3. A more
> modest step for v6 would just provide a way to find them (maybe
> something like -Wnon-top-basic-asm or -Wonly-top-basic-asm) and doc the
> current behavior as well as the upcoming change.
Warnings would be good.
My warning still holds: there are modes of compilation on some
machines where you can't clobber all registers without causing reload
failures. This is why Jeff didn't fix this in 1999. So, if we really
do want to clobber "all" registers in basic asm it'll take a lot of
work.
Andrew.