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Re: [PATCH] PR19331: Improve RTL bit-field simplification (take 2)


On Mon, 7 Feb 2005, Richard Henderson wrote:
> On Sun, Feb 06, 2005 at 05:15:58PM -0700, Roger Sayle wrote:
> > 	* simplify_rtx.c (simplify_relational_operaration_1): Explicitly
> > 	call gen_lowpart_common and gen_lowpart_SUBREG instead of calling
> > 	gen_lowpart.
>
> Why these instead of simplify_gen_subreg?

The use of gen_lowpart_common and gen_lowpart_SUBREG seems to be the
most popular idiom for implementing truncations in simplify-rtx.c
(even prior to my change), though I'll admit that with the time
pressure to restore bootstrap I was in a "gen_lowpart" mind-set.

If you'd prefer, I can prepare a follow-up patch to replace the above
uses with "simplify_gen_subreg (..., subreg_lowpart_offset (...))"
(including the instances in simplify_binary_operation)?  Perhaps we
could even add a "simplify_gen_lowpart (mode, x)"?

Roger
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