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From: "crazylht at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/55583] Extended shift instruction on x86-64 is not used, producing unoptimal code
Date: Mon, 30 May 2022 02:23:14 +0000 [thread overview]
Message-ID: <bug-55583-4-SgADP83JUH@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-55583-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55583
--- Comment #7 from Hongtao.liu <crazylht at gmail dot com> ---
i386 already has
12980(define_insn_and_split "*x86_shrd_2"
12981 [(set (match_operand:SI 0 "nonimmediate_operand")
12982 (ior:SI (lshiftrt:SI (match_dup 0)
12983 (match_operand:QI 2 "nonmemory_operand"))
12984 (ashift:SI (match_operand:SI 1 "register_operand")
12985 (minus:QI (const_int 32) (match_dup 2)))))
It need to be extended(or has new pre_reload splitters) to handle
1. op2 is constant, so minus is not necessary here.
2. swap op2 and (minus:QI (const_int 32) (match_dup 2) between lshiftrt and
ashift.
3. match_dup 0 is too restrict, we can have a extra emit_move_insn to set DEST.
next prev parent reply other threads:[~2022-05-30 2:23 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-04 0:06 [Bug rtl-optimization/55583] New: " mtkilpailut at torni dot org
2012-12-04 0:08 ` [Bug rtl-optimization/55583] " mtkilpailut at torni dot org
2012-12-04 0:21 ` hjl.tools at gmail dot com
2012-12-04 1:04 ` mikko.markus.torni at iki dot fi
2012-12-04 10:16 ` [Bug target/55583] " glisse at gcc dot gnu.org
2013-04-01 13:45 ` glisse at gcc dot gnu.org
2014-06-07 9:12 ` glisse at gcc dot gnu.org
2022-05-30 2:23 ` crazylht at gmail dot com [this message]
2022-11-01 3:24 ` cvs-commit at gcc dot gnu.org
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