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Re: Use simplify_replace_rtx rather than wrap_constant
- From: Alexandre Oliva <aoliva at redhat dot com>
- To: gcc-patches at gcc dot gnu dot org
- Cc: rdsandiford at googlemail dot com
- Date: Wed, 30 Sep 2009 06:16:59 -0300
- Subject: Re: Use simplify_replace_rtx rather than wrap_constant
- References: <87ljk1sr4c.fsf@firetop.home>
On Sep 26, 2009, Richard Sandiford <rdsandiford@googlemail.com> wrote:
> I wouldn't be entirely surprised if this patch introduces some post-VTA
> regressions that weren't picked up by the usual testing. But if it does,
> I think that's actually a useful thing, because we'll then be able to
> pinpoint the places that are doing invalid substitutions, losing the mode,
> or whatever. And if it doesn't introduce any regressions, well, even better!
I agree. I like the (followup) patch. In hindsight, the approach of
naively substituting RTX and adding CONSTs to preserve modes where
needed was quite poor. Thanks for cleaning this up.
The one bit I'm concerned about is the potential loss of modes in
CONST_INTs in VALUE equivalence tables and in the expansion of locs.
I'd expect some assertions to fail if this patch actually broke anything
in this regard, though. We'll see.
As far as I'm concerned, you can check it in, but I'm not entitled to
approve it.
--
Alexandre Oliva, freedom fighter http://FSFLA.org/~lxoliva/
You must be the change you wish to see in the world. -- Gandhi
Be Free! -- http://FSFLA.org/ FSF Latin America board member
Free Software Evangelist Red Hat Brazil Compiler Engineer