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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/101296] Addition of x86 addsub SLP patterned slowed down 433.milc by 12% on znver2 with -Ofast -flto Date: Fri, 02 Jul 2021 12:26:35 +0000 [thread overview] Message-ID: <bug-101296-4-2c5YmqUy5N@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-101296-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101296 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Ever confirmed|0 |1 Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot gnu.org Last reconfirmed| |2021-07-02 Status|UNCONFIRMED |ASSIGNED --- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> --- I will have a look next week. A quick look shows FMAs being used and addsub can break FMA detection until we get general optab support for fmaddsub and friends. So it might be { fma, fms } + blend compared to addsub + mul where the former maybe has lower latency though Agner says FMA (5c) + blend (1c) vs ADDSUB (3c) + MUL (3c). As said, I have to look into this in more detail. double a[4], b[4], c[4]; void foo () { c[0] = a[0] - b[0] * c[0]; c[1] = a[1] + b[1] * c[1]; c[2] = a[2] - b[2] * c[2]; c[3] = a[3] + b[3] * c[3]; } vmovapd a(%rip), %ymm2 vmovapd b(%rip), %ymm1 vmovapd b(%rip), %ymm0 vfmadd132pd c(%rip), %ymm2, %ymm1 vfnmadd132pd c(%rip), %ymm2, %ymm0 vshufpd $10, %ymm1, %ymm0, %ymm0 vmovapd %ymm0, c(%rip) vs. vmovapd b(%rip), %ymm1 vmovapd a(%rip), %ymm2 vmulpd c(%rip), %ymm1, %ymm0 vaddsubpd %ymm0, %ymm2, %ymm0 vmovapd %ymm0, c(%rip)
next prev parent reply other threads:[~2021-07-02 12:26 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-07-02 12:17 [Bug target/101296] New: " jamborm at gcc dot gnu.org 2021-07-02 12:26 ` rguenth at gcc dot gnu.org [this message] 2021-07-05 9:20 ` [Bug target/101296] " rguenth at gcc dot gnu.org 2021-07-05 9:30 ` rguenth at gcc dot gnu.org 2021-07-05 9:36 ` rguenth at gcc dot gnu.org 2021-07-06 13:02 ` rguenth at gcc dot gnu.org 2021-07-07 8:31 ` rguenth at gcc dot gnu.org 2021-08-22 19:26 ` hubicka at gcc dot gnu.org 2021-10-07 15:42 ` hubicka at gcc dot gnu.org 2021-10-08 6:56 ` rguenth at gcc dot gnu.org 2021-10-14 16:42 ` jamborm at gcc dot gnu.org 2023-01-31 11:26 ` jamborm at gcc dot gnu.org
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