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Re: new sign/zero extension elimination pass

From: Eric Botcazou <ebotcazou at adacore dot com>
To: Tom de Vries <tom at codesourcery dot com>
Cc: Paolo Bonzini <bonzini at gnu dot org>, gcc-patches at gcc dot gnu dot org, Bernd Schmidt <bernds at codesourcery dot com>
Date: Sat, 13 Nov 2010 10:50:53 +0100
Subject: Re: new sign/zero extension elimination pass
References: <4CBC698B.3080204@codesourcery.com> <AANLkTinJtmMZ0vhyP0B0fSkvYuTv-3DuZr0G5WwLZx44@mail.gmail.com> <4CDCF947.1030008@codesourcery.com>

> I profiled the pass on spec2000:
>
>                     -mabi=32     -mabi=64
> ee-pass (usr time):     0.70         1.16
> total   (usr time):   919.30       879.26
> ee-pass        (%):     0.08         0.13
>
> The pass takes 0.13% or less of the total usr runtime.

For how many hits?  What are the numbers with --param ee-max-propagate=0?

> Is it necessary to improve the runtime of this pass?

I've already given my opinion about the implementation.  The other passes in 
the compiler try hard not to rescan everything when a single bit changes; as 
currently written, yours doesn't.

-- 
Eric Botcazou

References:
- Re: new sign/zero extension elimination pass
  - From: Paolo Bonzini
- Re: new sign/zero extension elimination pass
  - From: Tom de Vries

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