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From: "ubizjak at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/100342] [10/11 Regression] wrong code with -O2 -fno-dse -fno-forward-propagate -mno-sse2
Date: Tue, 04 May 2021 15:14:01 +0000	[thread overview]
Message-ID: <bug-100342-4-XqjicHTrO5@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-100342-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100342

--- Comment #5 from Uroš Bizjak <ubizjak at gmail dot com> ---
The problem can be seen in _.pro_and_epilogue pass:

Starting with:

_.cmpelim

 2741: r14:DI=[sp:DI+0x38]
  ...
  368: di:DI=r14:DI
  ...
  613: si:QI=r14:QI
  ...
 2737: bp:DI=r14:DI
  ...
  658: strict_low_part(ax:QI)=bp:QI
 2275: dx:DI=si:DI
  ...
 2287: dx:DI=bp:DI
  710: dx:DI=bswap(dx:DI)


The pass converts:

_.pro_and_epilogue

rescanning insn with uid = 658.
insn 658: replaced reg 6 with 4
verify found no changes in insn with uid = 658.
verify found no changes in insn with uid = 2275.
deleting insn with uid = 2287.


 2741: r14:DI=[sp:DI+0x38]
  ...
  368: di:DI=r14:DI
  ...
  613: si:QI=r14:QI
  ...
 2737: bp:DI=r14:DI
  ...
  658: strict_low_part(ax:QI)=si:QI
 2275: dx:DI=si:DI
  ...
 2287: ?
  710: dx:DI=bswap(dx:DI)

Please note how the optimization removes insn 2287, assuming that rsi holds the
whole 64bit value ... Which is not true!

  parent reply	other threads:[~2021-05-04 15:14 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-29 20:10 [Bug target/100342] New: " zsojka at seznam dot cz
2021-04-30  6:51 ` [Bug rtl-optimization/100342] " rguenth at gcc dot gnu.org
2021-04-30  8:54 ` jakub at gcc dot gnu.org
2021-05-04 12:50 ` ubizjak at gmail dot com
2021-05-04 13:08 ` ubizjak at gmail dot com
2021-05-04 15:14 ` ubizjak at gmail dot com [this message]
2021-05-04 15:29 ` jakub at gcc dot gnu.org
2021-05-04 15:33 ` ubizjak at gmail dot com
2021-05-04 15:34 ` ubizjak at gmail dot com
2021-05-04 16:36 ` jakub at gcc dot gnu.org
2021-05-04 16:57 ` jakub at gcc dot gnu.org
2021-05-05 10:59 ` jakub at gcc dot gnu.org
2021-05-05 15:12 ` jakub at gcc dot gnu.org
2021-05-06  5:22 ` crazylht at gmail dot com
2021-05-15  8:14 ` cvs-commit at gcc dot gnu.org
2021-05-31 14:08 ` cvs-commit at gcc dot gnu.org
2021-05-31 14:56 ` [Bug rtl-optimization/100342] [10 " jakub at gcc dot gnu.org
2022-05-10  8:18 ` cvs-commit at gcc dot gnu.org
2022-05-10 10:45 ` jakub at gcc dot gnu.org

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