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From: "crazylht at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/95524] Subtimal codegen for shift by constant for v16qi/v32qi under -march=skylake
Date: Mon, 15 Jun 2020 13:16:02 +0000	[thread overview]
Message-ID: <bug-95524-4-Z1LEZ9G7AM@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-95524-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95524

--- Comment #3 from Hongtao.liu <crazylht at gmail dot com> ---
(In reply to Hongtao.liu from comment #0)

> icc has
> ---
> ashift(char __vector(16)):
>         vpsllw    xmm1, xmm0, 5                                 #9.16
>         vpand     xmm0, xmm1, XMMWORD PTR .L_2il0floatpacket.0[rip] #9.16
>         ret                                                     #9.16
> ashift2(char __vector(32), char __vector(32)):
>         vpsllw    ymm2, ymm0, 5                                 #15.16
>         vpand     ymm0, ymm2, YMMWORD PTR .L_2il0floatpacket.1[rip] #15.16
>         ret                                                     #15.16
> ashiftrt(char __vector(16)):
>         vpsrlw    xmm1, xmm0, 5                                 #21.16
>         vpand     xmm0, xmm1, XMMWORD PTR .L_2il0floatpacket.2[rip] #21.16
>         ret                                                     #21.16
> arshiftrt2(char __vector(32)):
>         vpsrlw    ymm1, ymm0, 5                                 #27.16
>         vpand     ymm0, ymm1, YMMWORD PTR .L_2il0floatpacket.3[rip] #27.16
>         ret                                                     #27.16
>         .long  
> 

ICC seems to generate inaccurate instructions for ashiftrt, but clang is right,
still better than gcc, refer to https://godbolt.org/z/ttV5xY

  parent reply	other threads:[~2020-06-15 13:16 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-04  6:24 [Bug target/95524] New: " crazylht at gmail dot com
2020-06-11  8:21 ` [Bug target/95524] " crazylht at gmail dot com
2020-06-15 13:08 ` crazylht at gmail dot com
2020-06-15 13:16 ` crazylht at gmail dot com [this message]
2020-06-17  8:05 ` cvs-commit at gcc dot gnu.org
2020-07-09  6:56 ` crazylht at gmail dot com
2021-08-21 18:27 ` pinskia at gcc dot gnu.org

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