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From: "hjl.tools at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/107172] [13 Regression] wrong code with "-O1 -ftree-vrp" on x86_64-linux-gnu since r13-1268-g8c99e307b20c502e Date: Mon, 17 Oct 2022 15:59:18 +0000 [thread overview] Message-ID: <bug-107172-4-Z29v4UgLBE@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-107172-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107172 --- Comment #37 from H.J. Lu <hjl.tools at gmail dot com> --- (In reply to Segher Boessenkool from comment #33) > (In reply to H.J. Lu from comment #32) > > > There is no actual comparison with 0, that is just notation. > > > > True. But simplify-rtx.cc simplifies > > > > (ltu (reg 17) (const_int 0)) > > > > to false when reg 17 is set. > > Is set? What does that even mean? Is set to what? (reg 17) was set to 1. > > Use the actual comparison isn't issue. The issue is how > > > > (ltu (reg 17) (const_int 0)) > > > > should be simplified when reg 17 is known to be set. > > You need to look at the setter. It cannot be simplified otherwise. The backend knows how to evaluate (ltu:SI (const_int 1 [0x1]) (const_int 0 [0])) from (ltu:SI (reg:CCC 17 flags) (const_int 0 [0])) where (reg:CCC 17 flags) was set to a constant by backend.
next prev parent reply other threads:[~2022-10-17 15:59 UTC|newest] Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-10-06 17:51 [Bug tree-optimization/107172] New: wrong code with "-O1 -ftree-vrp" on x86_64-linux-gnu zhendong.su at inf dot ethz.ch 2022-10-06 18:02 ` [Bug tree-optimization/107172] [13 Regression] " pinskia at gcc dot gnu.org 2022-10-06 18:46 ` [Bug tree-optimization/107172] [13 Regression] wrong code with "-O1 -ftree-vrp" on x86_64-linux-gnu since r13-1268-g8c99e307b20c502e marxin at gcc dot gnu.org 2022-10-07 7:21 ` rguenth at gcc dot gnu.org 2022-10-07 12:17 ` aldyh at gcc dot gnu.org 2022-10-07 21:04 ` [Bug target/107172] " hjl.tools at gmail dot com 2022-10-07 22:20 ` hjl.tools at gmail dot com 2022-10-09 21:51 ` roger at nextmovesoftware dot com 2022-10-10 18:32 ` segher at gcc dot gnu.org 2022-10-10 18:34 ` segher at gcc dot gnu.org 2022-10-10 19:16 ` hjl.tools at gmail dot com 2022-10-10 20:55 ` segher at gcc dot gnu.org 2022-10-11 0:10 ` hjl.tools at gmail dot com 2022-10-11 16:16 ` segher at gcc dot gnu.org 2022-10-11 17:16 ` hjl.tools at gmail dot com 2022-10-11 18:05 ` segher at gcc dot gnu.org 2022-10-11 19:49 ` roger at nextmovesoftware dot com 2022-10-11 20:26 ` segher at gcc dot gnu.org 2022-10-11 22:30 ` hjl.tools at gmail dot com 2022-10-11 22:38 ` hjl.tools at gmail dot com 2022-10-12 7:17 ` crazylht at gmail dot com 2022-10-12 7:25 ` crazylht at gmail dot com 2022-10-12 8:11 ` segher at gcc dot gnu.org 2022-10-12 17:50 ` hjl.tools at gmail dot com 2022-10-13 3:38 ` crazylht at gmail dot com 2022-10-13 8:14 ` ubizjak at gmail dot com 2022-10-13 12:31 ` crazylht at gmail dot com 2022-10-13 16:54 ` hjl.tools at gmail dot com 2022-10-13 17:49 ` hjl.tools at gmail dot com 2022-10-13 22:07 ` segher at gcc dot gnu.org 2022-10-13 22:12 ` segher at gcc dot gnu.org 2022-10-13 22:20 ` segher at gcc dot gnu.org 2022-10-13 22:23 ` hjl.tools at gmail dot com 2022-10-13 22:34 ` hjl.tools at gmail dot com 2022-10-15 14:53 ` segher at gcc dot gnu.org 2022-10-17 3:28 ` crazylht at gmail dot com 2022-10-17 7:48 ` rguenth at gcc dot gnu.org 2022-10-17 7:55 ` rguenth at gcc dot gnu.org 2022-10-17 15:59 ` hjl.tools at gmail dot com [this message] 2022-10-17 22:01 ` segher at gcc dot gnu.org 2022-10-18 0:19 ` hjl.tools at gmail dot com 2022-10-18 14:44 ` segher at gcc dot gnu.org 2022-10-18 19:54 ` hjl.tools at gmail dot com 2022-10-18 20:14 ` segher at gcc dot gnu.org 2022-10-20 17:25 ` pinskia at gcc dot gnu.org 2022-10-20 19:03 ` hjl.tools at gmail dot com 2022-10-22 21:14 ` segher at gcc dot gnu.org 2022-10-27 18:42 ` cvs-commit at gcc dot gnu.org 2022-10-28 9:11 ` roger at nextmovesoftware dot com 2022-10-28 15:48 ` hjl.tools at gmail dot com 2022-11-30 17:33 ` jakub at gcc dot gnu.org 2022-11-30 21:52 ` hjl.tools at gmail dot com 2023-05-30 13:44 ` cvs-commit at gcc dot gnu.org 2023-07-27 14:47 ` shaohua.li at inf dot ethz.ch
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