From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1851) id 29D403858D28; Fri, 5 Nov 2021 16:09:38 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 29D403858D28 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Martin Liska To: gcc-cvs@gcc.gnu.org Subject: [gcc r11-9209] Speed up jump table switch detection. X-Act-Checkin: gcc X-Git-Author: Martin Liska X-Git-Refname: refs/heads/releases/gcc-11 X-Git-Oldrev: b555a1469ea285166363e5de327231e2ee698d93 X-Git-Newrev: 95c7ef9fbcf2c4b760c296fae597f093b6ee9aaa Message-Id: <20211105160938.29D403858D28@sourceware.org> Date: Fri, 5 Nov 2021 16:09:38 +0000 (GMT) X-BeenThere: gcc-cvs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 05 Nov 2021 16:09:38 -0000 https://gcc.gnu.org/g:95c7ef9fbcf2c4b760c296fae597f093b6ee9aaa commit r11-9209-g95c7ef9fbcf2c4b760c296fae597f093b6ee9aaa Author: Martin Liska Date: Fri Aug 13 17:22:35 2021 +0200 Speed up jump table switch detection. PR tree-optimization/100393 gcc/ChangeLog: * tree-switch-conversion.c (group_cluster::dump): Use get_comparison_count. (jump_table_cluster::find_jump_tables): Pre-compute number of comparisons and then decrement it. Cache also max_ratio. (jump_table_cluster::can_be_handled): Change signature. * tree-switch-conversion.h (get_comparison_count): New. (cherry picked from commit c517cf2e685e2903b591d63c1034ff9726cb3822) Diff: --- gcc/tree-switch-conversion.c | 42 +++++++++++++++++++++++------------------- gcc/tree-switch-conversion.h | 14 ++++++++++++-- 2 files changed, 35 insertions(+), 21 deletions(-) diff --git a/gcc/tree-switch-conversion.c b/gcc/tree-switch-conversion.c index 7f65c4ce839..8fc5eaa3033 100644 --- a/gcc/tree-switch-conversion.c +++ b/gcc/tree-switch-conversion.c @@ -1090,7 +1090,7 @@ group_cluster::dump (FILE *f, bool details) for (unsigned i = 0; i < m_cases.length (); i++) { simple_cluster *sc = static_cast (m_cases[i]); - comparison_count += sc->m_range_p ? 2 : 1; + comparison_count += sc->get_comparison_count (); } unsigned HOST_WIDE_INT range = get_range (get_low (), get_high ()); @@ -1185,11 +1185,24 @@ jump_table_cluster::find_jump_tables (vec &clusters) min.quick_push (min_cluster_item (0, 0, 0)); + unsigned HOST_WIDE_INT max_ratio + = (optimize_insn_for_size_p () + ? param_jump_table_max_growth_ratio_for_size + : param_jump_table_max_growth_ratio_for_speed); + for (unsigned i = 1; i <= l; i++) { /* Set minimal # of clusters with i-th item to infinite. */ min.quick_push (min_cluster_item (INT_MAX, INT_MAX, INT_MAX)); + /* Pre-calculate number of comparisons for the clusters. */ + HOST_WIDE_INT comparison_count = 0; + for (unsigned k = 0; k <= i - 1; k++) + { + simple_cluster *sc = static_cast (clusters[k]); + comparison_count += sc->get_comparison_count (); + } + for (unsigned j = 0; j < i; j++) { unsigned HOST_WIDE_INT s = min[j].m_non_jt_cases; @@ -1200,10 +1213,15 @@ jump_table_cluster::find_jump_tables (vec &clusters) if ((min[j].m_count + 1 < min[i].m_count || (min[j].m_count + 1 == min[i].m_count && s < min[i].m_non_jt_cases)) - && can_be_handled (clusters, j, i - 1)) + && can_be_handled (clusters, j, i - 1, max_ratio, + comparison_count)) min[i] = min_cluster_item (min[j].m_count + 1, j, s); + + simple_cluster *sc = static_cast (clusters[j]); + comparison_count -= sc->get_comparison_count (); } + gcc_checking_assert (comparison_count == 0); gcc_checking_assert (min[i].m_count != INT_MAX); } @@ -1241,7 +1259,9 @@ jump_table_cluster::find_jump_tables (vec &clusters) bool jump_table_cluster::can_be_handled (const vec &clusters, - unsigned start, unsigned end) + unsigned start, unsigned end, + unsigned HOST_WIDE_INT max_ratio, + unsigned HOST_WIDE_INT comparison_count) { /* If the switch is relatively small such that the cost of one indirect jump on the target are higher than the cost of a @@ -1260,10 +1280,6 @@ jump_table_cluster::can_be_handled (const vec &clusters, if (start == end) return true; - unsigned HOST_WIDE_INT max_ratio - = (optimize_insn_for_size_p () - ? param_jump_table_max_growth_ratio_for_size - : param_jump_table_max_growth_ratio_for_speed); unsigned HOST_WIDE_INT range = get_range (clusters[start]->get_low (), clusters[end]->get_high ()); /* Check overflow. */ @@ -1277,18 +1293,6 @@ jump_table_cluster::can_be_handled (const vec &clusters, if (lhs < range) return false; - /* First make quick guess as each cluster - can add at maximum 2 to the comparison_count. */ - if (lhs > 2 * max_ratio * (end - start + 1)) - return false; - - unsigned HOST_WIDE_INT comparison_count = 0; - for (unsigned i = start; i <= end; i++) - { - simple_cluster *sc = static_cast (clusters[i]); - comparison_count += sc->m_range_p ? 2 : 1; - } - return lhs <= max_ratio * comparison_count; } diff --git a/gcc/tree-switch-conversion.h b/gcc/tree-switch-conversion.h index d76f19b57f6..a375e52636e 100644 --- a/gcc/tree-switch-conversion.h +++ b/gcc/tree-switch-conversion.h @@ -180,6 +180,13 @@ public: return tree_int_cst_equal (get_low (), get_high ()); } + /* Return number of comparisons needed for the case. */ + unsigned + get_comparison_count () + { + return m_range_p ? 2 : 1; + } + /* Low value of the case. */ tree m_low; @@ -267,9 +274,12 @@ public: static vec find_jump_tables (vec &clusters); /* Return true when cluster starting at START and ending at END (inclusive) - can build a jump-table. */ + can build a jump-table. COMPARISON_COUNT is number of comparison + operations needed if the clusters are expanded as decision tree. + MAX_RATIO tells about the maximum code growth (in percent). */ static bool can_be_handled (const vec &clusters, unsigned start, - unsigned end); + unsigned end, unsigned HOST_WIDE_INT max_ratio, + unsigned HOST_WIDE_INT comparison_count); /* Return true if cluster starting at START and ending at END (inclusive) is profitable transformation. */