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From: "ubizjak at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/95632] Redundant zero extension
Date: Tue, 16 Jun 2020 07:15:11 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95632

--- Comment #5 from Uro=C5=A1 Bizjak <ubizjak at gmail dot com> ---
(In reply to Mel Chen from comment #2)
> Is it possible to pretend that we have a pattern that can match xor (reg:=
SI
> 80), (reg: SI 72), 0xa001 in combine pass?
> And then, if the constant part is too large to put in to the immediate pa=
rt,
> it can be split to 2 xor in split pass.

Please note that the combine pass has its own (rather limited) splitter, it=
 is
documented in the second part of "Defining How to Split Instructions"
paragraph. The example is dealing with the instruction that has too large
immediate part, and looks similar to your problem.=