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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/98117] [8/9/10/11 Regression] wrong code with "-O3 -fno-tree-scev-cprop" since r8-1163-g7078979b291419f3 Date: Mon, 07 Dec 2020 08:51:45 +0000 [thread overview] Message-ID: <bug-98117-4-ZVkOMf0Ti0@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-98117-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98117 --- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> --- <bb 2> [local count: 118111600]: c_lsm.6_7 = c; niters.8_1 = -c_lsm.6_7; if (c_lsm.6_7 > 240) goto <bb 11>; [10.00%] else goto <bb 6>; [90.00%] <bb 6> [local count: 106300440]: _18 = niters.8_1 + 240; _19 = _18 >> 4; # RANGE [1, 15] NONZERO 15 bnd.9_17 = _19 + 1; but here c == 0 and thus _19 + 1 is 16. The number of latch invocations is 255 but the number of iterations is that + 1 and thus zero in the IVs type. This is why we have num_itersm1 and so I guess /* Peeling algorithm guarantees that vector loop bound is at least ONE, we set range information to make niters analyzer's life easier. */ if (stmts != NULL && log_vf) set_range_info (niters_vector, VR_RANGE, wi::to_wide (build_int_cst (type, 1)), wi::to_wide (fold_build2 (RSHIFT_EXPR, type, TYPE_MAX_VALUE (type), log_vf))); needs to use TYPE_MAX_VALUE + 1 >> log_vf here to be on the safe side for the "non-representable" niter value.
next prev parent reply other threads:[~2020-12-07 8:51 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-12-03 11:31 [Bug tree-optimization/98117] New: wrong code with "-O3 -fno-tree-scev-cprop" suochenyao at 163 dot com 2020-12-03 11:51 ` [Bug tree-optimization/98117] [8/9/10/11 Regression] wrong code with "-O3 -fno-tree-scev-cprop" since r8-1163-g7078979b291419f3 marxin at gcc dot gnu.org 2020-12-03 12:30 ` rguenth at gcc dot gnu.org 2020-12-07 8:39 ` rguenth at gcc dot gnu.org 2020-12-07 8:51 ` rguenth at gcc dot gnu.org [this message] 2020-12-07 9:27 ` rguenth at gcc dot gnu.org 2020-12-07 11:06 ` cvs-commit at gcc dot gnu.org 2020-12-07 11:06 ` [Bug tree-optimization/98117] [8/9/10 " rguenth at gcc dot gnu.org 2021-01-11 14:10 ` cvs-commit at gcc dot gnu.org 2021-03-17 9:35 ` [Bug tree-optimization/98117] [8/9 " cvs-commit at gcc dot gnu.org 2021-04-26 10:46 ` [Bug tree-optimization/98117] [8 " cvs-commit at gcc dot gnu.org 2021-04-26 10:49 ` rguenth at gcc dot gnu.org
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