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Re: Tree tail merging breaks __builtin_unreachable optimization

From: Michael Matz <matz at suse dot de>
To: Steven Bosscher <stevenb dot gcc at gmail dot com>
Cc: Ulrich Weigand <uweigand at de dot ibm dot com>, gcc-patches at gcc dot gnu dot org, tom at codesourcery dot com
Date: Thu, 5 Jul 2012 14:44:23 +0200 (CEST)
Subject: Re: Tree tail merging breaks __builtin_unreachable optimization
References: <201207041702.q64H2GGj017517@d06av02.portsmouth.uk.ibm.com> <CABu31nNywL+ipdw1zf-squZM6T_Xqn-YW-0zw-Uv-vJ2AQ2cPA@mail.gmail.com>

Hi,

On Wed, 4 Jul 2012, Steven Bosscher wrote:

> On Wed, Jul 4, 2012 at 7:02 PM, Ulrich Weigand <uweigand@de.ibm.com> wrote:
> > Any suggestions how to fix this?  Should tail merging detect
> > __builtin_unreachable and not merge such block?
> 
> That seems to be the most straight-forward thing to do. I don't think
> there are any other passes that do this kind of code merging.

What do we gain by delaying to remove these blocks until RTL?  AFAICS not 
much if anything.  So removing those on the tree level would make more 
sense.

Ciao,
Michael.

Follow-Ups:
- Re: Tree tail merging breaks __builtin_unreachable optimization
  - From: Richard Guenther

References:
- Tree tail merging breaks __builtin_unreachable optimization
  - From: Ulrich Weigand
- Re: Tree tail merging breaks __builtin_unreachable optimization
  - From: Steven Bosscher

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