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From: "crazylht at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/110170] Sub-optimal conditional jumps in conditional-swap with floating point
Date: Mon, 12 Jun 2023 09:09:31 +0000	[thread overview]
Message-ID: <bug-110170-4-IdpXPTLlnV@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-110170-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110170

--- Comment #9 from Hongtao.liu <crazylht at gmail dot com> ---
(In reply to Hongtao.liu from comment #8)
> ix86_expand_sse_fp_minmax failed since rtx_equal_p (cmp_op0, if_true) is
> false, 
> 
> 249(reg:DF 86 [ _1 ])  (if_true)
> 250(reg:DF 83 [ _2 ])  (if_false)
> 251(reg:DF 82 [ _1 ])  (cmp0_op0)
> 252(reg:DF 83 [ _2 ])  (cmp1_op1)
> 
> but here if_true is just a copy from cmp_op0 but with different REGNO,
> rtx_equal_p seems too conservative here.
> 

But if_convert didn't maintain DF_CHAIN info, and and backend can't get
DF_REG_DEF_* info to figure out if_true is just a single_set of cmp_op0.


With -march=x86-64-v2, gcc generates 

        movsd   (%rdi), %xmm2
        movsd   (%rsi), %xmm1
        movapd  %xmm2, %xmm0
        movapd  %xmm1, %xmm3
        cmpltsd %xmm1, %xmm0
        maxsd   %xmm2, %xmm3
        blendvpd        %xmm0, %xmm2, %xmm1
        movsd   %xmm3, (%rsi)
        movsd   %xmm1, (%rdi)
        ret

Which can be further optimized: cmpltsd + blendvpd -> minsd

  parent reply	other threads:[~2023-06-12  9:09 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-08 11:31 [Bug tree-optimization/110170] New: " antoshkka at gmail dot com
2023-06-08 11:34 ` [Bug tree-optimization/110170] " pinskia at gcc dot gnu.org
2023-06-08 11:57 ` [Bug target/110170] " antoshkka at gmail dot com
2023-06-08 13:32 ` pinskia at gcc dot gnu.org
2023-06-08 19:40 ` pinskia at gcc dot gnu.org
2023-06-09  5:38 ` crazylht at gmail dot com
2023-06-09  6:40 ` crazylht at gmail dot com
2023-06-09  7:01 ` crazylht at gmail dot com
2023-06-09  7:03 ` rguenth at gcc dot gnu.org
2023-06-12  2:17 ` crazylht at gmail dot com
2023-06-12  9:09 ` crazylht at gmail dot com [this message]
2023-07-04  5:46 ` crazylht at gmail dot com
2023-07-06  5:54 ` cvs-commit at gcc dot gnu.org
2023-07-10  1:06 ` cvs-commit at gcc dot gnu.org
2023-07-11  9:51 ` antoshkka at gmail dot com
2023-07-11 13:23 ` crazylht at gmail dot com
2023-07-11 13:57 ` cvs-commit at gcc dot gnu.org
2023-07-18 10:28 ` rguenth at gcc dot gnu.org
2023-07-18 10:33 ` crazylht at gmail dot com
2023-07-18 13:48 ` rguenth at gcc dot gnu.org
2023-07-21  8:18 ` rguenth at gcc dot gnu.org
2023-10-17  6:31 ` cvs-commit at gcc dot gnu.org
2023-10-17 11:14 ` cvs-commit at gcc dot gnu.org
2023-10-26  5:30 ` cvs-commit at gcc dot gnu.org

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