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From: "rearnsha at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/106187] armhf: Miscompilation at O2 level (O0 / O1 are working) Date: Mon, 18 Jul 2022 15:45:55 +0000 [thread overview] Message-ID: <bug-106187-4-gHE82bzfa6@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-106187-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106187 Richard Earnshaw <rearnsha at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |rguenth at gcc dot gnu.org --- Comment #26 from Richard Earnshaw <rearnsha at gcc dot gnu.org> --- git bisect points to commit r11-9688 resolving the issue. Before that commit the ivopts pass generates: ivtmp.761_217 = (unsigned int) &au; _222 = &bu + 4; ivtmp.767_220 = (unsigned int) _222; _225 = (unsigned int) &au; _228 = _225 + 16; <bb 9> [local count: 858993457]: # prephitmp_136 = PHI <pretmp_120(10), 1073741824(8)> # prephitmp_32 = PHI <pretmp_18(10), 2147483648(8)> # ivtmp.761_278 = PHI <ivtmp.761_216(10), ivtmp.761_217(8)> # ivtmp.767_218 = PHI <ivtmp.767_219(10), ivtmp.767_220(8)> _16 = prephitmp_32 ^ prephitmp_136; _223 = (void *) ivtmp.761_278; MEM[(unsigned int *)_223] = _16; ivtmp.761_216 = ivtmp.761_278 + 4; if (ivtmp.761_216 != _228) goto <bb 10>; [75.00%] else goto <bb 11>; [25.00%] <bb 10> [local count: 644245086]: _230 = (void *) ivtmp.761_216; pretmp_120 = MEM[(unsigned int *)_230]; _229 = (void *) ivtmp.767_218; pretmp_18 = MEM[(unsigned int *)_229]; ivtmp.767_219 = ivtmp.767_218 + 4; goto <bb 9>; [100.00%] And once that patch is applied we get: ivtmp.761_217 = (unsigned int) &au; ivtmp.766_220 = (unsigned int) &bu; _223 = (unsigned int) &au; _225 = _223 + 16; <bb 9> [local count: 858993457]: # prephitmp_136 = PHI <pretmp_120(10), 1073741824(8)> # prephitmp_32 = PHI <pretmp_18(10), 2147483648(8)> # ivtmp.761_278 = PHI <ivtmp.761_216(10), ivtmp.761_217(8)> # ivtmp.766_218 = PHI <ivtmp.766_219(10), ivtmp.766_220(8)> _16 = prephitmp_32 ^ prephitmp_136; _222 = (void *) ivtmp.761_278; MEM[(unsigned int *)_222] = _16; ivtmp.761_216 = ivtmp.761_278 + 4; if (ivtmp.761_216 != _225) goto <bb 10>; [75.00%] else goto <bb 11>; [25.00%] The main difference being that in the 'bad' code we start with &bu + 4, while in the good code we start with &bu. I'm afraid I don't know enough about this code to take this further. Richi?
next prev parent reply other threads:[~2022-07-18 15:45 UTC|newest] Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-07-04 16:23 [Bug c++/106187] New: armhf: Miscompilation with -O2 mathieu.malaterre at gmail dot com 2022-07-04 16:37 ` [Bug c++/106187] " mathieu.malaterre at gmail dot com 2022-07-04 16:37 ` mathieu.malaterre at gmail dot com 2022-07-04 16:42 ` [Bug c++/106187] armhf: Miscompilation at all optimization levels mathieu.malaterre at gmail dot com 2022-07-04 20:19 ` pinskia at gcc dot gnu.org 2022-07-04 20:22 ` pinskia at gcc dot gnu.org 2022-07-05 7:18 ` [Bug target/106187] " mathieu.malaterre at gmail dot com 2022-07-05 7:46 ` [Bug target/106187] armhf: Miscompilation at O2 level (O0 / O1 are working) jan.wassenberg at gmail dot com 2022-07-05 8:00 ` mathieu.malaterre at gmail dot com 2022-07-07 7:50 ` mathieu.malaterre at gmail dot com 2022-07-07 8:00 ` mathieu.malaterre at gmail dot com 2022-07-07 9:38 ` rearnsha at gcc dot gnu.org 2022-07-08 9:01 ` mathieu.malaterre at gmail dot com 2022-07-08 9:01 ` mathieu.malaterre at gmail dot com 2022-07-08 9:03 ` mathieu.malaterre at gmail dot com 2022-07-08 13:50 ` rearnsha at gcc dot gnu.org 2022-07-08 13:59 ` malat at debian dot org 2022-07-08 14:16 ` rearnsha at gcc dot gnu.org 2022-07-08 14:18 ` malat at debian dot org 2022-07-08 14:51 ` rearnsha at gcc dot gnu.org 2022-07-08 15:03 ` malat at debian dot org 2022-07-08 17:24 ` rearnsha at gcc dot gnu.org 2022-07-08 17:31 ` rearnsha at gcc dot gnu.org 2022-07-08 19:27 ` jan.wassenberg at gmail dot com 2022-07-14 13:03 ` rearnsha at gcc dot gnu.org 2022-07-14 13:18 ` rearnsha at gcc dot gnu.org 2022-07-14 16:09 ` pinskia at gcc dot gnu.org 2022-07-18 15:45 ` rearnsha at gcc dot gnu.org [this message] 2022-07-18 15:48 ` rearnsha at gcc dot gnu.org 2022-07-19 7:27 ` rguenth at gcc dot gnu.org 2022-07-19 9:00 ` rearnsha at gcc dot gnu.org 2022-07-19 9:13 ` rguenth at gcc dot gnu.org 2022-07-21 9:25 ` rearnsha at gcc dot gnu.org 2022-07-22 12:52 ` rearnsha at gcc dot gnu.org 2022-07-22 13:24 ` rearnsha at gcc dot gnu.org 2022-07-25 6:12 ` rguenth at gcc dot gnu.org 2022-07-25 9:44 ` rearnsha at gcc dot gnu.org 2022-07-25 9:50 ` rguenther at suse dot de 2022-07-25 9:59 ` rearnsha at gcc dot gnu.org 2022-07-25 10:24 ` rguenth at gcc dot gnu.org 2022-07-25 10:26 ` [Bug rtl-optimization/106187] " rguenth at gcc dot gnu.org 2022-07-25 10:33 ` rearnsha at gcc dot gnu.org 2022-07-25 10:42 ` rguenth at gcc dot gnu.org 2022-07-25 10:48 ` rearnsha at gcc dot gnu.org 2022-07-25 11:03 ` rguenther at suse dot de 2022-07-25 11:05 ` rguenth at gcc dot gnu.org 2022-07-25 13:04 ` rearnsha at gcc dot gnu.org 2022-07-25 14:45 ` rguenther at suse dot de 2022-07-27 13:35 ` rearnsha at gcc dot gnu.org 2022-07-28 16:51 ` rearnsha at gcc dot gnu.org 2022-08-03 9:07 ` cvs-commit at gcc dot gnu.org 2022-08-03 9:16 ` rearnsha at gcc dot gnu.org 2022-08-10 7:06 ` malat at debian dot org 2022-08-10 7:11 ` pinskia at gcc dot gnu.org 2022-09-02 9:28 ` malat at debian dot org 2022-09-02 12:30 ` cvs-commit at gcc dot gnu.org 2022-09-02 12:32 ` rearnsha at gcc dot gnu.org 2022-09-02 14:07 ` cvs-commit at gcc dot gnu.org 2022-09-27 15:28 ` malat at debian dot org 2022-09-27 15:54 ` rearnsha at gcc dot gnu.org 2024-01-20 17:20 ` pinskia at gcc dot gnu.org
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