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Re: [patch] cse.c: Remove an optimization that never triggers.


On Fri, 2005-01-28 at 07:47 -0500, Kazu Hirata wrote:
> Hi,
> 
> 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
> hppa2.0w-hp-hpux11.11.
> 
> 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  <kazu@cs.umass.edu>
> 
> 	* cse.c (fold_rtx) <PC>: Don't optimize.
OK.
jeff



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