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From: "cvs-commit at gcc dot gnu.org" <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: Thu, 06 Jul 2023 05:54:38 +0000 [thread overview] Message-ID: <bug-110170-4-kvwx5NEBHi@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 #11 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by hongtao Liu <liuhongt@gcc.gnu.org>: https://gcc.gnu.org/g:37a231cc7594d12ba0822077018aad751a6fb94e commit r14-2337-g37a231cc7594d12ba0822077018aad751a6fb94e Author: liuhongt <hongtao.liu@intel.com> Date: Wed Jul 5 13:45:11 2023 +0800 Disparage slightly for the alternative which move DFmode between SSE_REGS and GENERAL_REGS. For testcase void __cond_swap(double* __x, double* __y) { bool __r = (*__x < *__y); auto __tmp = __r ? *__x : *__y; *__y = __r ? *__y : *__x; *__x = __tmp; } GCC-14 with -O2 and -march=x86-64 options generates the following code: __cond_swap(double*, double*): movsd xmm1, QWORD PTR [rdi] movsd xmm0, QWORD PTR [rsi] comisd xmm0, xmm1 jbe .L2 movq rax, xmm1 movapd xmm1, xmm0 movq xmm0, rax .L2: movsd QWORD PTR [rsi], xmm1 movsd QWORD PTR [rdi], xmm0 ret rax is used to save and restore DFmode value. In RA both GENERAL_REGS and SSE_REGS cost zero since we didn't disparage the alternative in movdf_internal pattern, according to register allocation order, GENERAL_REGS is allocated. The patch add ? for alternative (r,v) and (v,r) just like we did for movsf/hf/bf_internal pattern, after that we get optimal RA. __cond_swap: .LFB0: .cfi_startproc movsd (%rdi), %xmm1 movsd (%rsi), %xmm0 comisd %xmm1, %xmm0 jbe .L2 movapd %xmm1, %xmm2 movapd %xmm0, %xmm1 movapd %xmm2, %xmm0 .L2: movsd %xmm1, (%rsi) movsd %xmm0, (%rdi) ret gcc/ChangeLog: PR target/110170 * config/i386/i386.md (movdf_internal): Disparage slightly for 2 alternatives (r,v) and (v,r) by adding constraint modifier '?'. gcc/testsuite/ChangeLog: * gcc.target/i386/pr110170-3.c: New test.
next prev parent reply other threads:[~2023-07-06 5:54 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 2023-07-04 5:46 ` crazylht at gmail dot com 2023-07-06 5:54 ` cvs-commit at gcc dot gnu.org [this message] 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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