On Mon, Jul 26, 2021 at 4:18 PM Richard Sandiford <richard.sandif...@arm.com> wrote: > > Aldy Hernandez <al...@redhat.com> writes: > > This patch replaces the evrp_range_analyzer in the loop versioning code > > with an on-demand ranger. > > > > Everything was pretty straightforward, except that range_of_expr requires > > a gimple statement as context to provide context aware ranges. I didn't see > > a convient place where the statement was saved, so I made a vector indexed > > by SSA names. As an alternative, I tried to use the loop's first statement, > > but that proved to be insufficient. > > The mapping is one-to-many though: there can be multiple statements > for each SSA name. Maybe that doesn't matter in this context and > any of the statements can act as a representative. > > I'm surprised that the loop's first statement didn't work though, > since the SSA name is supposedly known to be loop-invariant. What went > wrong when you tried that?
I was looking at the first statement of loop_info->block_list and one of the dg.exp=loop-versioning* tests failed. Perhaps I should have used the loop itself, as in the attached patch. With this patch all of the loop-versioning tests pass. > > > I am not familiar with loop versioning, but if the DOM walk was only > > necessary for the calls to record_ranges_from_stmt, this too could be > > removed as the ranger will work without it. > > Yeah, that was the only reason. If the information is available at > version_for_unity (I guess it is) then we should just avoid recording > the versioning there if so. > > How expensive is the check? If the result is worth caching, perhaps > we should have two bitmaps: the existing one, and one that records > whether we've checked a particular SSA name. > > If the check is relatively cheap then that won't be worth it though. If you're asking about the range_of_expr check, that's all cached, so it should be pretty cheap. Besides, we're no longer calculating ranges for each statement in the IL, as we were doing in lv_dom_walker with evrp's record_ranges_from_stmt. Only statements of interest are queried. How about this patch, pending tests? Aldy
From 8a350003d950869499d729921008abdb491d3a5e Mon Sep 17 00:00:00 2001 From: Aldy Hernandez <al...@redhat.com> Date: Sat, 24 Jul 2021 12:29:28 +0200 Subject: [PATCH] Replace evrp use in loop versioning with ranger. This patch replaces the evrp_range_analyzer in the loop versioning code with an on-demand ranger. Tested on x86-64 Linux. gcc/ChangeLog: * gimple-loop-versioning.cc (lv_dom_walker::lv_dom_walker): Remove use of m_range_analyzer. (loop_versioning::lv_dom_walker::before_dom_children): Same. (loop_versioning::lv_dom_walker::after_dom_children): Remove. (loop_versioning::prune_loop_conditions): Replace vr_values use with range_query interface. (pass_loop_versioning::execute): Use ranger. --- gcc/gimple-loop-versioning.cc | 44 ++++++++++++----------------------- 1 file changed, 15 insertions(+), 29 deletions(-) diff --git a/gcc/gimple-loop-versioning.cc b/gcc/gimple-loop-versioning.cc index 4b70c5a4aab..46c3a508c8d 100644 --- a/gcc/gimple-loop-versioning.cc +++ b/gcc/gimple-loop-versioning.cc @@ -30,19 +30,17 @@ along with GCC; see the file COPYING3. If not see #include "tree-ssa-loop.h" #include "ssa.h" #include "tree-scalar-evolution.h" -#include "tree-chrec.h" #include "tree-ssa-loop-ivopts.h" #include "fold-const.h" #include "tree-ssa-propagate.h" #include "tree-inline.h" #include "domwalk.h" -#include "alloc-pool.h" -#include "vr-values.h" -#include "gimple-ssa-evrp-analyze.h" #include "tree-vectorizer.h" #include "omp-general.h" #include "predict.h" #include "tree-into-ssa.h" +#include "gimple-range.h" +#include "tree-cfg.h" namespace { @@ -261,14 +259,10 @@ private: lv_dom_walker (loop_versioning &); edge before_dom_children (basic_block) FINAL OVERRIDE; - void after_dom_children (basic_block) FINAL OVERRIDE; private: /* The parent pass. */ loop_versioning &m_lv; - - /* Used to build context-dependent range information. */ - evrp_range_analyzer m_range_analyzer; }; /* Used to simplify statements based on conditions that are established @@ -308,7 +302,7 @@ private: bool analyze_block (basic_block); bool analyze_blocks (); - void prune_loop_conditions (class loop *, vr_values *); + void prune_loop_conditions (class loop *); bool prune_conditions (); void merge_loop_info (class loop *, class loop *); @@ -500,7 +494,7 @@ loop_info::worth_versioning_p () const } loop_versioning::lv_dom_walker::lv_dom_walker (loop_versioning &lv) - : dom_walker (CDI_DOMINATORS), m_lv (lv), m_range_analyzer (false) + : dom_walker (CDI_DOMINATORS), m_lv (lv) { } @@ -509,26 +503,12 @@ loop_versioning::lv_dom_walker::lv_dom_walker (loop_versioning &lv) edge loop_versioning::lv_dom_walker::before_dom_children (basic_block bb) { - m_range_analyzer.enter (bb); - if (bb == bb->loop_father->header) - m_lv.prune_loop_conditions (bb->loop_father, &m_range_analyzer); - - for (gimple_stmt_iterator si = gsi_start_bb (bb); !gsi_end_p (si); - gsi_next (&si)) - m_range_analyzer.record_ranges_from_stmt (gsi_stmt (si), false); + m_lv.prune_loop_conditions (bb->loop_father); return NULL; } -/* Process BB after processing the blocks it dominates. */ - -void -loop_versioning::lv_dom_walker::after_dom_children (basic_block bb) -{ - m_range_analyzer.leave (bb); -} - /* Decide whether to replace VAL with a new value in a versioned loop. Return the new value if so, otherwise return null. */ @@ -1483,18 +1463,21 @@ loop_versioning::analyze_blocks () LOOP. */ void -loop_versioning::prune_loop_conditions (class loop *loop, vr_values *vrs) +loop_versioning::prune_loop_conditions (class loop *loop) { loop_info &li = get_loop_info (loop); int to_remove = -1; bitmap_iterator bi; unsigned int i; + int_range_max r; EXECUTE_IF_SET_IN_BITMAP (&li.unity_names, 0, i, bi) { tree name = ssa_name (i); - const value_range_equiv *vr = vrs->get_value_range (name); - if (vr && !vr->may_contain_p (build_one_cst (TREE_TYPE (name)))) + gimple *stmt = first_stmt (loop->header); + + if (get_range_query (cfun)->range_of_expr (r, name, stmt) + && !r.contains_p (build_one_cst (TREE_TYPE (name)))) { if (dump_enabled_p ()) dump_printf_loc (MSG_NOTE, find_loop_location (loop), @@ -1810,7 +1793,10 @@ pass_loop_versioning::execute (function *fn) if (number_of_loops (fn) <= 1) return 0; - return loop_versioning (fn).run (); + enable_ranger (fn); + unsigned int ret = loop_versioning (fn).run (); + disable_ranger (fn); + return ret; } } // anon namespace -- 2.31.1