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From: Paolo Bonzini <bonzini@gnu.org>
Date: Sat, 30 Jul 2011 16:35:00 -0000
Message-ID: <CAHFMJ7t5Be5ikj3yjPsDcHt+pbUfSWbyVu5UTLFc-YT0381A7g@mail.gmail.com>
Subject: Re: PING: PATCH [4/n]: Prepare x32: Permute the conversion and addition if one operand is a constant
To: "H.J. Lu" <hjl.tools@gmail.com>
Cc: Uros Bizjak <ubizjak@gmail.com>, gcc-patches@gcc.gnu.org
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On Sat, Jul 30, 2011 at 00:32, H.J. Lu <hjl.tools@gmail.com> wrote:
> The whole approach doesn't work. The testcase at
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49721#c1
>
> shows GCC depends on transforming:
>
> (zero_extend:DI (plus:SI (FOO:SI) (const_int Y)))
>
> to
>
> (plus:DI (zero_extend:DI (FOO:SI)) (const_int Y))
>
> Otherwise we either get compiler crash or wrong codes.

Please explain how/why here or in the BZ.  Compiler crashes can be
fixed, wrong code is often a symptom of latent bugs.

Paolo