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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: Jeff Law <law at redhat dot com>
- Cc: Jakub Jelinek <jakub 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: Tue, 12 Apr 2016 10:35:05 +0200 (CEST)
- 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> <570C0D91 dot 2030500 at redhat dot com>
On Mon, 11 Apr 2016, Jeff Law wrote:
> On 04/08/2016 10:10 AM, Jakub Jelinek 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).
> I thought the atomic support added support for statements with multiple
> outputs?
Maybe on a branch. Historically all gimples had the ability to have
multiple DEFs but this was removed as having excessive memory requirement.
Later DEFs handling was simplified and we no longer keep def "operands"
explicit but the iterators know how to get at all possible defs. Which
makes it "currently only ASMs can have multiple (non-virtual) defs".
See ssa-iterators.h:op_iter_init and op_iter_next_def.
Richard.