public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
* [Bug target/101464] New: Replace zveroupper with vpxor @ 2021-07-15 18:26 hjl.tools at gmail dot com 2021-07-16 1:54 ` [Bug target/101464] " crazylht at gmail dot com ` (3 more replies) 0 siblings, 4 replies; 5+ messages in thread From: hjl.tools at gmail dot com @ 2021-07-15 18:26 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101464 Bug ID: 101464 Summary: Replace zveroupper with vpxor Product: gcc Version: 12.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: hjl.tools at gmail dot com Target Milestone: --- Target: i386, x86-64 [hjl@gnu-cfl-2 pr101456]$ cat y.c #include <x86intrin.h> extern __m256d x, y; void foo (void) { x = y; } [hjl@gnu-cfl-2 pr101456]$ gcc -S -O2 -mavx2 y.c [hjl@gnu-cfl-2 pr101456]$ cat y.s .file "y.c" .text .p2align 4 .globl foo .type foo, @function foo: .LFB5667: .cfi_startproc vmovapd y(%rip), %ymm0 vmovapd %ymm0, x(%rip) vzeroupper ret .cfi_endproc .LFE5667: .size foo, .-foo .ident "GCC: (GNU) 11.1.1 20210531 (Red Hat 11.1.1-3)" .section .note.GNU-stack,"",@progbits [hjl@gnu-cfl-2 pr101456]$ vzeroupper can be replaced by a single pxor. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug target/101464] Replace zveroupper with vpxor 2021-07-15 18:26 [Bug target/101464] New: Replace zveroupper with vpxor hjl.tools at gmail dot com @ 2021-07-16 1:54 ` crazylht at gmail dot com 2021-07-16 2:00 ` hjl.tools at gmail dot com ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: crazylht at gmail dot com @ 2021-07-16 1:54 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101464 Hongtao.liu <crazylht at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |crazylht at gmail dot com --- Comment #1 from Hongtao.liu <crazylht at gmail dot com> --- >From the implementation perspective, we need to record all usage of sse registers which is AVX_U128_DIRTY and clear them all. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug target/101464] Replace zveroupper with vpxor 2021-07-15 18:26 [Bug target/101464] New: Replace zveroupper with vpxor hjl.tools at gmail dot com 2021-07-16 1:54 ` [Bug target/101464] " crazylht at gmail dot com @ 2021-07-16 2:00 ` hjl.tools at gmail dot com 2021-07-16 6:26 ` rguenth at gcc dot gnu.org 2021-07-16 12:07 ` hjl.tools at gmail dot com 3 siblings, 0 replies; 5+ messages in thread From: hjl.tools at gmail dot com @ 2021-07-16 2:00 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101464 --- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> --- Created attachment 51159 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51159&action=edit A patch ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug target/101464] Replace zveroupper with vpxor 2021-07-15 18:26 [Bug target/101464] New: Replace zveroupper with vpxor hjl.tools at gmail dot com 2021-07-16 1:54 ` [Bug target/101464] " crazylht at gmail dot com 2021-07-16 2:00 ` hjl.tools at gmail dot com @ 2021-07-16 6:26 ` rguenth at gcc dot gnu.org 2021-07-16 12:07 ` hjl.tools at gmail dot com 3 siblings, 0 replies; 5+ messages in thread From: rguenth at gcc dot gnu.org @ 2021-07-16 6:26 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101464 --- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> --- But in the long discussion involving vzeroupper and HTM aborts in glibc memory functions it came up that vpxor is _not_ properly clearing the upper state and thus does _not_ remove the penalty that following non-VEX SSE instructions get? ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug target/101464] Replace zveroupper with vpxor 2021-07-15 18:26 [Bug target/101464] New: Replace zveroupper with vpxor hjl.tools at gmail dot com ` (2 preceding siblings ...) 2021-07-16 6:26 ` rguenth at gcc dot gnu.org @ 2021-07-16 12:07 ` hjl.tools at gmail dot com 3 siblings, 0 replies; 5+ messages in thread From: hjl.tools at gmail dot com @ 2021-07-16 12:07 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101464 H.J. Lu <hjl.tools at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution|--- |INVALID --- Comment #4 from H.J. Lu <hjl.tools at gmail dot com> --- (In reply to Richard Biener from comment #3) > But in the long discussion involving vzeroupper and HTM aborts in glibc > memory functions it came up that vpxor is _not_ properly clearing the upper > state and thus does _not_ remove the penalty that following non-VEX SSE > instructions get? From https://sourceware.org/bugzilla/show_bug.cgi?id=27457 we can't use VPXOR to replace VZEROUPPER. ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-07-16 12:07 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-07-15 18:26 [Bug target/101464] New: Replace zveroupper with vpxor hjl.tools at gmail dot com 2021-07-16 1:54 ` [Bug target/101464] " crazylht at gmail dot com 2021-07-16 2:00 ` hjl.tools at gmail dot com 2021-07-16 6:26 ` rguenth at gcc dot gnu.org 2021-07-16 12:07 ` hjl.tools at gmail dot com
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).