[PATCH] PR rtl-optimization/14851: Move three-linked combine pass before two-linked

[Bernd Schmidt]

Uros Bizjak wrote:

> I would like to resend a combiner patch that moves three-linked combine 
> pass before two-linked pass. A long explanation with a benchmark result 
> can be found in http://gcc.gnu.org/ml/gcc-patches/2004-09/msg02193.html.
> 
> This patch was considered too risky for 4.0 stage3 and thus queued for 
> 4.1 via PR 17652.
> 
> Patch, diffed against current mainline is attached to this message. 
> Patch is bootstrapped on i386-pc-linux-gnu, regtested c,c++.
> 
> 2005-03-14 Uros Bizjak <uros@kss-loka.si>
> 
>    PR rtl-optimization/14851
>    PR target/19150
>    * combine.c (combine_instructions): Move 'three linked insns'
>    pass before 'two linked insns' pass.

This may or may not be a good idea, but the problem you describe sounds 
more like an issue with the machine description - it shouldn't be 
sensitive to such implementation details in combine.


Bernd