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Re: [patch] cse.c: Remove an optimization that never triggers.
- From: Jeffrey A Law <law at redhat dot com>
- To: Kazu Hirata <kazu at cs dot umass dot edu>
- Cc: gcc-patches at gcc dot gnu dot org, dave dot anglin at nrc dot ca
- Date: Fri, 28 Jan 2005 10:02:45 -0700
- Subject: Re: [patch] cse.c: Remove an optimization that never triggers.
- Organization: Red Hat, Inc
- References: <firstname.lastname@example.org>
- Reply-to: law at redhat dot com
On Fri, 2005-01-28 at 07:47 -0500, Kazu Hirata wrote:
> Attached is a patch to remove an optimization that never triggers.
> The condition of the "if" statement that this patch is removing is
> never true during bootstrap and make-check of i686-pc-linux-gnu and
> Plus, even if this optimization triggered, this would be
> simplification of a control-flow instruction based on no information
> except that from INSN itself, which sounds like a CFG cleanup's job.
> The patch removes the optimization and teaches fold_rtx to return X
> early if PC is passed. Note that the rest of fold_rtx never deals
> with PC.
> According to CVS (both the current one and old-gcc), this optimization
> is hardly ever touched except when somebody is sweeping through the
> whole GCC to make mechanical changes.
> Tested on i686-pc-linux-gnu. OK to apply?
> Kazu Hirata
> 2005-01-27 Kazu Hirata <email@example.com>
> * cse.c (fold_rtx) <PC>: Don't optimize.