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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/68050] SLP vectorization should negate constants to match up + vs - Date: Sun, 29 Aug 2021 04:39:42 +0000 [thread overview] Message-ID: <bug-68050-4-p0j6tIiU1n@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-68050-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68050 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Last reconfirmed|2015-10-22 00:00:00 |2021-8-28 --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- WE do this now: <bb 3> [local count: 1063004409]: # ivtmp.13_20 = PHI <ivtmp.13_15(3), 0(2)> vect__1.5_14 = MEM <vector(2) double> [(double *)&x + ivtmp.13_20 * 1]; vect__5.7_12 = vect__1.5_14 + { -3.0e+0, -3.0e+0 }; vect__2.6_13 = vect__1.5_14 + { 3.0e+0, 3.0e+0 }; _7 = VEC_PERM_EXPR <vect__2.6_13, vect__5.7_12, { 0, 3 }>; MEM <vector(2) double> [(double *)&z + ivtmp.13_20 * 1] = _7; ivtmp.13_15 = ivtmp.13_20 + 16; if (ivtmp.13_15 != 8192) goto <bb 3>; [99.00%] else goto <bb 4>; [1.00%] But if we use long instead of double, we get: <bb 3> [local count: 1063004409]: # ivtmp.12_20 = PHI <ivtmp.12_15(3), 0(2)> vect__1.5_14 = MEM <vector(2) long int> [(long int *)&x + ivtmp.12_20 * 1]; vect__2.6_13 = vect__1.5_14 + { 3, -3 }; MEM <vector(2) long int> [(long int *)&z + ivtmp.12_20 * 1] = vect__2.6_13; ivtmp.12_15 = ivtmp.12_20 + 16; if (ivtmp.12_15 != 8192) goto <bb 3>; [99.00%] else goto <bb 4>; [1.00%] Note clang has worse code for the VECT_PERM_EXPR but does the same thing as GCC here. So the difference between long and double for GCC at least comes from having IR difference in that the "a - 3" in the long case is actually "a + -3".
next prev parent reply other threads:[~2021-08-29 4:39 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-10-22 10:03 [Bug tree-optimization/68050] New: " rguenth at gcc dot gnu.org 2015-10-22 10:03 ` [Bug tree-optimization/68050] " rguenth at gcc dot gnu.org 2021-08-29 4:39 ` pinskia at gcc dot gnu.org [this message] 2021-08-30 7:44 ` rguenth at gcc dot gnu.org
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