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Re: Initial shrink-wrapping patch

From: Ian Lance Taylor <iant at google dot com>
To: Bernd Schmidt <bernds at codesourcery dot com>
Cc: Richard Henderson <rth at redhat dot com>, Richard Guenther <richard dot guenther at gmail dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>, richard dot sandiford at linaro dot org
Date: Wed, 05 Oct 2011 20:17:16 -0700
Subject: Re: Initial shrink-wrapping patch
References: <4E5E7342.9050103@codesourcery.com> <g462lcbc22.fsf@richards-thinkpad.stglab.manchester.uk.ibm.com> <4E6E9857.50600@t-online.de> <g4ehzklu0r.fsf@richards-thinkpad.stglab.manchester.uk.ibm.com> <4E6F37D9.9000108@t-online.de> <g4pqj4k702.fsf@richards-thinkpad.stglab.manchester.uk.ibm.com> <4E6F4B90.2050408@codesourcery.com> <g4hb4gk2xa.fsf@richards-thinkpad.stglab.manchester.uk.ibm.com> <4E6F786E.6080407@codesourcery.com> <4E712FD6.5030109@redhat.com> <4E8239ED.9020004@codesourcery.com> <4E85F395.3030006@redhat.com> <4E8B8469.2090605@codesourcery.com> <4E8B88E7.3090107@redhat.com> <CAFiYyc2VePBTofTZ+N6Ck_fpzgXdz7N8zncbtgX2OGnW87_7uA@mail.gmail.com> <4E8C7ED0.3090705@codesourcery.com> <4E8C83FA.3000607@redhat.com> <4E8C912C.2060805@codesourcery.com> <CAKOQZ8z_Dkoc6e2Oy5mXLaiz6mz4HBMauR5N=uePxyMCJ-tz7A@mail.gmail.com> <4E8CEC99.2000105@codesourcery.com>

Bernd Schmidt <bernds@codesourcery.com> writes:

> This appears to be because the split prologue contains a jump, which
> means the find_many_sub_blocks call reorders the block numbers, and our
> indices into bb_flags are off.
>
> I'm testing the following patch, but it won't finish today - feel free
> to test and check it in, or to just disable shrink-wrapping with split
> prologues.

Thinking about it I think this is the wrong approach.  The -fsplit-stack
code by definition has to wrap the entire function and it can not modify
any callee-saved registers.  We should do shrink wrapping before
-fsplit-stack, not the other way around.

Ian

Follow-Ups:
- Re: Initial shrink-wrapping patch
  - From: Bernd Schmidt

References:
- Re: Initial shrink-wrapping patch
  - From: Bernd Schmidt
- Re: Initial shrink-wrapping patch
  - From: Richard Henderson
- Re: Initial shrink-wrapping patch
  - From: Richard Guenther
- Re: Initial shrink-wrapping patch
  - From: Bernd Schmidt
- Re: Initial shrink-wrapping patch
  - From: Richard Henderson
- Re: Initial shrink-wrapping patch
  - From: Bernd Schmidt
- Re: Initial shrink-wrapping patch
  - From: Ian Lance Taylor
- Re: Initial shrink-wrapping patch
  - From: Bernd Schmidt

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