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Re: [PATCH] diagnose unsupported uses of hardware register variables (PR 88000)
- From: Segher Boessenkool <segher at kernel dot crashing dot org>
- To: Jakub Jelinek <jakub at redhat dot com>
- Cc: Martin Sebor <msebor at gmail dot com>, Gcc Patch List <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 14 Nov 2018 05:35:06 -0600
- Subject: Re: [PATCH] diagnose unsupported uses of hardware register variables (PR 88000)
- References: <edacc336-963e-37e1-804d-44870c12bd55@gmail.com> <20181114094757.GO11625@tucnak>
On Wed, Nov 14, 2018 at 10:47:57AM +0100, Jakub Jelinek wrote:
> This makes no sense to me. There is nothing unsupported in passing
> a local hard register variable to a function, that is well defined,
> and as your testcase changes show, you broke quite some completely valid
> testcases with that.
What could perhaps be useful is a warning for a local register var that
is not used in any asm?
> What doesn't work as the reporter expect is assumption that local hard
> register variables that live across function calls must have their values
> preserved; they can be modified by the callees.
It would be really nice if we could fix that :-)
Segher