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Re: [Patch,AVR]: Fix PR36467, PR49687 (better widening mul)
- From: Richard Henderson <rth at redhat dot com>
- To: Georg-Johann Lay <avr at gjlay dot de>
- Cc: gcc-patches at gcc dot gnu dot org, Eric Weddington <eric dot weddington at atmel dot com>, Denis Chertykov <chertykov at gmail dot com>, Anatoly Sokolov <aesok at post dot ru>
- Date: Mon, 18 Jul 2011 11:10:41 -0700
- Subject: Re: [Patch,AVR]: Fix PR36467, PR49687 (better widening mul)
- References: <4E24541F.7050606@gjlay.de> <4E247155.70604@redhat.com> <4E2475EA.4080506@gjlay.de>
On 07/18/2011 11:05 AM, Georg-Johann Lay wrote:
> What's bad with pre-reload splits?
> The only weak point is in target-independent code because there
> is nothing like split1_completed and other missing information
> for better pass-awareness.
Nothing's wrong with pre-reload splits.
However, what you've done is try very hard to work around reload
doing the Right Thing with constant spilling, namely re-generate
the constant rather than spill and restore it. I cannot believe
that's the right way to proceed.
>> Does anything break if we simply move pass_split_after_reload
>> earlier? Right to the beginning of pass_postreload for instance.
>> Seems to me that every port would gain by optimizing the stuff
>> that comes out of the post-reload splitters.
>
> I don't know the reason for that or if other machines rely on it.
And that is something we need to find out.
r~