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Re: [PATCH] Fix ssa coalescing with inline asm (PR middle-end/70593)
- From: Richard Biener <rguenther at suse dot de>
- To: Jakub Jelinek <jakub at redhat dot com>
- Cc: Jeff Law <law at redhat dot com>,Bernd Schmidt <bschmidt at redhat dot com>,Alexandre Oliva <aoliva at redhat dot com>,gcc-patches at gcc dot gnu dot org
- Date: Fri, 08 Apr 2016 19:08:06 +0200
- Subject: Re: [PATCH] Fix ssa coalescing with inline asm (PR middle-end/70593)
- Authentication-results: sourceware.org; auth=none
- References: <20160408145422 dot GU19207 at tucnak dot redhat dot com> <9DA16A93-95B8-4A4B-BB31-1D34C11E88C7 at suse dot de> <20160408161005 dot GW19207 at tucnak dot redhat dot com>
On April 8, 2016 6:10:05 PM GMT+02:00, Jakub Jelinek <jakub@redhat.com> wrote:
>On Fri, Apr 08, 2016 at 06:04:38PM +0200, Richard Biener wrote:
>> Hmm, don't we simply want to do this for all stmts (OK, only asm have
>multiple defs...)?
>
>For all stmts that have multiple defs (which is only GIMPLE_ASM right
>now).
>Though, of course, if you want, unconditionally doing:
> bool first = true;
> FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_DEF)
> if (first)
> first = false;
> else
> live_track_process_use (live, var);
>would work too and would be prepared for future hypothetical stmts
>with multiple defs.
Yes, that's what I am suggesting.
The reason why I'm not calling
>live_track_process_use
>on the first SSA_OP_DEF operand is that it is completely useless,
>because the first live_track_process_def will undo it immediately.
>For the above, I guess I'd just slightly adjust the comment, instead of
> For GIMPLE_ASM as the only statement which can have
> more than one SSA_NAME definition, ...
>say
> For stmts with more than one SSA_NAME definition, ...
Sounds good.
Richard.
> Jakub