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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/64099] [5 Regression] ~15% runtime increase for fatigue.f90. Date: Thu, 11 Dec 2014 15:02:00 -0000 [thread overview] Message-ID: <bug-64099-4-zngUm7YQtu@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-64099-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64099 --- Comment #9 from Richard Biener <rguenth at gcc dot gnu.org> --- For r217826 vs. r217827 the assembly differences show a larger stack frame while the optimized dump differences are net positive (more memory CSE happens and loads get removed - which might increase register pressure enough). For r216727 vs. r216728 the order of functions output changes, there are no real changes in the optimized dumps. Both rev. changes cause operand order to be swapped for some instructions which can, given TER, result in significant scheduling differences in the RTL expansion. One thing is for example that the reassoc pass produces non-canonical operand order but its operand order might be more optimal in practice (the canonical order is just canonicalization for commutative operands). As we deal with single-use chains there we might consider "swapping" SSA names (swap SSA_NAME_VERSION) to preserve its ordering over a fold_stmt call. No, doing that doesn't make a significant difference :/ For reference: Index: gcc/tree-ssa-reassoc.c =================================================================== --- gcc/tree-ssa-reassoc.c (revision 217827) +++ gcc/tree-ssa-reassoc.c (working copy) @@ -3602,6 +3602,16 @@ rewrite_expr_tree (gimple stmt, unsigned update_stmt (stmt); } + if (commutative_tree_code (gimple_assign_rhs_code (stmt)) + && tree_swap_operands_p (new_rhs1, oe->op, true)) + { + gcc_assert (TREE_CODE (new_rhs1) == SSA_NAME + && TREE_CODE (oe->op) == SSA_NAME); + std::swap (SSA_NAME_VERSION (new_rhs1), SSA_NAME_VERSION (oe->op)); + std::swap (ssa_name (SSA_NAME_VERSION (new_rhs1)), + ssa_name (SSA_NAME_VERSION (oe->op))); + } + if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, " into ");
next prev parent reply other threads:[~2014-12-11 15:02 UTC|newest] Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-11-28 10:47 [Bug middle-end/64099] New: " dominiq at lps dot ens.fr 2014-11-28 11:03 ` [Bug middle-end/64099] " rguenth at gcc dot gnu.org 2014-11-28 11:03 ` rguenth at gcc dot gnu.org 2014-11-28 13:16 ` rguenth at gcc dot gnu.org 2014-11-28 14:03 ` dominiq at lps dot ens.fr 2014-11-28 15:54 ` dominiq at lps dot ens.fr 2014-11-28 19:37 ` dominiq at lps dot ens.fr 2014-12-11 13:58 ` rguenth at gcc dot gnu.org 2014-12-11 15:02 ` rguenth at gcc dot gnu.org [this message] 2015-01-15 11:42 ` rguenth at gcc dot gnu.org 2015-01-15 12:32 ` dominiq at lps dot ens.fr 2015-03-03 16:02 ` law at redhat dot com 2015-04-15 9:47 ` [Bug middle-end/64099] [5/6 " dominiq at lps dot ens.fr 2015-04-15 11:24 ` dominiq at lps dot ens.fr 2015-04-15 13:15 ` dominiq at lps dot ens.fr 2015-04-22 12:02 ` jakub at gcc dot gnu.org 2015-07-16 9:20 ` rguenth at gcc dot gnu.org 2021-05-14 9:47 ` [Bug middle-end/64099] [9/10/11/12 " jakub at gcc dot gnu.org 2021-06-01 8:06 ` rguenth at gcc dot gnu.org 2022-05-27 9:35 ` [Bug middle-end/64099] [10/11/12/13 " rguenth at gcc dot gnu.org 2022-06-28 10:31 ` jakub at gcc dot gnu.org 2023-07-07 10:30 ` [Bug middle-end/64099] [11/12/13/14 " rguenth at gcc dot gnu.org
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