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From: "jens.seifert at de dot ibm.com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/106770] PPCLE: Unnecessary xxpermdi before mfvsrd Date: Mon, 29 Aug 2022 09:57:39 +0000 [thread overview] Message-ID: <bug-106770-4-K8AlytM8HR@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-106770-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106770 --- Comment #2 from Jens Seifert <jens.seifert at de dot ibm.com> --- vec_extract(vr, 1) should extract the left element. But xxpermdi x,x,x,3 extracts the right element. Looks like a bug in vec_extract for PPCLE and not a problem regarding unnecessary xxpermdi. Using assembly for the subtract: int cmp3(double a, double b) { vector double va = vec_promote(a, 0); vector double vb = vec_promote(b, 0); vector long long vlt = (vector long long)vec_cmplt(va, vb); vector long long vgt = (vector long long)vec_cmplt(vb, va); vector signed long long vr; __asm__ volatile("vsubudm %0,%1,%2":"=v"(vr):"v"(vlt),"v"(vgt):); //vector signed long long vr = vec_sub(vlt, vgt); return vec_extract(vr, 1); } generates: _Z4cmp3dd: .LFB2: .cfi_startproc xxpermdi 1,1,1,0 xxpermdi 2,2,2,0 xvcmpgtdp 32,2,1 xvcmpgtdp 33,1,2 #APP # 34 "cmpdouble.C" 1 vsubudm 0,0,1 # 0 "" 2 #NO_APP mfvsrd 3,32 extsw 3,3 " Looks like the compile knows about the vec_promote doing splat and at the end extracts the non-preferred right element instead of the expected left element.
next prev parent reply other threads:[~2022-08-29 9:57 UTC|newest] Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-08-29 7:52 [Bug target/106770] New: " jens.seifert at de dot ibm.com 2022-08-29 8:16 ` [Bug target/106770] " jens.seifert at de dot ibm.com 2022-08-29 9:57 ` jens.seifert at de dot ibm.com [this message] 2023-02-27 16:26 ` segher at gcc dot gnu.org 2023-02-27 17:57 ` jens.seifert at de dot ibm.com 2023-02-27 23:06 ` segher at gcc dot gnu.org 2023-02-28 7:23 ` jens.seifert at de dot ibm.com 2023-02-28 16:57 ` segher at gcc dot gnu.org 2023-03-02 6:11 ` [Bug target/106770] powerpc64le: " jskumari at gcc dot gnu.org 2023-03-02 7:36 ` jskumari at gcc dot gnu.org 2023-03-02 12:42 ` jskumari at gcc dot gnu.org 2023-03-02 13:26 ` segher at gcc dot gnu.org 2023-03-03 6:02 ` jskumari at gcc dot gnu.org
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