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Diffstat (limited to 'gcc/gimple-range-path.cc')
| -rw-r--r-- | gcc/gimple-range-path.cc | 398 |
1 files changed, 398 insertions, 0 deletions
diff --git a/gcc/gimple-range-path.cc b/gcc/gimple-range-path.cc new file mode 100644 index 0000000..c616b65 --- /dev/null +++ b/gcc/gimple-range-path.cc @@ -0,0 +1,398 @@ +/* Basic block path solver. + Copyright (C) 2021 Free Software Foundation, Inc. + Contributed by Aldy Hernandez <aldyh@redhat.com>. + +This file is part of GCC. + +GCC is free software; you can redistribute it and/or modify it under +the terms of the GNU General Public License as published by the Free +Software Foundation; either version 3, or (at your option) any later +version. + +GCC is distributed in the hope that it will be useful, but WITHOUT ANY +WARRANTY; without even the implied warranty of MERCHANTABILITY or +FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + for more details. + +You should have received a copy of the GNU General Public License +along with GCC; see the file COPYING3. If not see +<http://www.gnu.org/licenses/>. */ + +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "backend.h" +#include "tree.h" +#include "gimple.h" +#include "cfganal.h" +#include "value-range.h" +#include "gimple-range.h" +#include "tree-pretty-print.h" +#include "gimple-range-path.h" +#include "ssa.h" + +// Internal construct to help facilitate debugging of solver. +#define DEBUG_SOLVER (0 && dump_file) + +path_range_query::path_range_query (gimple_ranger &ranger) + : m_ranger (ranger) +{ + m_cache = new ssa_global_cache; + m_has_cache_entry = BITMAP_ALLOC (NULL); + m_path = NULL; +} + +path_range_query::~path_range_query () +{ + BITMAP_FREE (m_has_cache_entry); + delete m_cache; +} + +// Mark cache entry for NAME as unused. + +void +path_range_query::clear_cache (tree name) +{ + unsigned v = SSA_NAME_VERSION (name); + bitmap_clear_bit (m_has_cache_entry, v); +} + +// If NAME has a cache entry, return it in R, and return TRUE. + +inline bool +path_range_query::get_cache (irange &r, tree name) +{ + if (!gimple_range_ssa_p (name)) + return get_global_range_query ()->range_of_expr (r, name); + + unsigned v = SSA_NAME_VERSION (name); + if (bitmap_bit_p (m_has_cache_entry, v)) + return m_cache->get_global_range (r, name); + + return false; +} + +// Set the cache entry for NAME to R. + +void +path_range_query::set_cache (const irange &r, tree name) +{ + unsigned v = SSA_NAME_VERSION (name); + bitmap_set_bit (m_has_cache_entry, v); + m_cache->set_global_range (name, r); +} + +void +path_range_query::dump (FILE *dump_file) +{ + if (m_path->is_empty ()) + return; + + unsigned i; + bitmap_iterator bi; + extern void dump_ranger (FILE *, const vec<basic_block> &); + + fprintf (dump_file, "Path is (length=%d):\n", m_path->length ()); + dump_ranger (dump_file, *m_path); + + fprintf (dump_file, "Imports:\n"); + EXECUTE_IF_SET_IN_BITMAP (m_imports, 0, i, bi) + { + tree name = ssa_name (i); + print_generic_expr (dump_file, name, TDF_SLIM); + fprintf (dump_file, "\n"); + } + + m_cache->dump (dump_file); +} + +void +path_range_query::debug () +{ + dump (stderr); +} + +// Return the range of NAME at the end of the path being analyzed. + +bool +path_range_query::internal_range_of_expr (irange &r, tree name, gimple *stmt) +{ + if (!irange::supports_type_p (TREE_TYPE (name))) + return false; + + if (get_cache (r, name)) + return true; + + + basic_block bb = stmt ? gimple_bb (stmt) : exit_bb (); + if (stmt && range_defined_in_block (r, name, bb)) + { + if (TREE_CODE (name) == SSA_NAME) + r.intersect (gimple_range_global (name)); + + set_cache (r, name); + return true; + } + + r.set_varying (TREE_TYPE (name)); + return true; +} + +bool +path_range_query::range_of_expr (irange &r, tree name, gimple *stmt) +{ + if (internal_range_of_expr (r, name, stmt)) + { + if (r.undefined_p ()) + m_undefined_path = true; + + return true; + } + return false; +} + +bool +path_range_query::unreachable_path_p () +{ + return m_undefined_path; +} + +// Return the range of STMT at the end of the path being analyzed. + +bool +path_range_query::range_of_stmt (irange &r, gimple *stmt, tree) +{ + tree type = gimple_range_type (stmt); + + if (!irange::supports_type_p (type)) + return false; + + if (!fold_range (r, stmt, this)) + r.set_varying (type); + + return true; +} + +// Initialize the current path to PATH. The current block is set to +// the entry block to the path. +// +// Note that the blocks are in reverse order, so the exit block is +// path[0]. + +void +path_range_query::set_path (const vec<basic_block> &path) +{ + gcc_checking_assert (path.length () > 1); + m_path = &path; + m_pos = m_path->length () - 1; + bitmap_clear (m_has_cache_entry); +} + +// Return the range of the result of PHI in R. + +void +path_range_query::ssa_range_in_phi (irange &r, gphi *phi) +{ + tree name = gimple_phi_result (phi); + basic_block bb = gimple_bb (phi); + + // We experimented with querying ranger's range_on_entry here, but + // the performance penalty was too high, for hardly any improvements. + if (at_entry ()) + { + // Try fold just in case we can resolve simple things like PHI <5(99), 6(88)>. + if (!fold_range (r, phi, this)) + r.set_varying (TREE_TYPE (name)); + + return; + } + + basic_block prev = prev_bb (); + edge e_in = find_edge (prev, bb); + unsigned nargs = gimple_phi_num_args (phi); + + for (size_t i = 0; i < nargs; ++i) + if (e_in == gimple_phi_arg_edge (phi, i)) + { + tree arg = gimple_phi_arg_def (phi, i); + + if (!get_cache (r, arg)) + r.set_varying (TREE_TYPE (name)); + + return; + } + gcc_unreachable (); +} + +// If NAME is defined in BB, set R to the range of NAME, and return +// TRUE. Otherwise, return FALSE. + +bool +path_range_query::range_defined_in_block (irange &r, tree name, basic_block bb) +{ + gimple *def_stmt = SSA_NAME_DEF_STMT (name); + basic_block def_bb = gimple_bb (def_stmt); + + if (def_bb != bb) + return false; + + if (gimple_code (def_stmt) == GIMPLE_PHI) + ssa_range_in_phi (r, as_a<gphi *> (def_stmt)); + else if (!range_of_stmt (r, def_stmt, name)) + r.set_varying (TREE_TYPE (name)); + + if (bb) + m_non_null.adjust_range (r, name, bb); + + if (DEBUG_SOLVER && (bb || !r.varying_p ())) + { + fprintf (dump_file, "range_defined_in_block (BB%d) for ", bb ? bb->index : -1); + print_generic_expr (dump_file, name, TDF_SLIM); + fprintf (dump_file, " is "); + r.dump (dump_file); + fprintf (dump_file, "\n"); + } + + // We may have an artificial statement not in the IL. + if (!bb && r.varying_p ()) + return false; + + return true; +} + +// Precompute ranges defined in the current block, or ranges +// that are exported on an edge to the next block. + +void +path_range_query::precompute_ranges_in_block (basic_block bb) +{ + bitmap_iterator bi; + int_range_max r, cached_range; + unsigned i; + + // Force recalculation of any names in the cache that are defined in + // this block. This can happen on interdependent SSA/phis in loops. + EXECUTE_IF_SET_IN_BITMAP (m_imports, 0, i, bi) + { + tree name = ssa_name (i); + gimple *def_stmt = SSA_NAME_DEF_STMT (name); + basic_block def_bb = gimple_bb (def_stmt); + + if (def_bb == bb) + clear_cache (name); + } + + // Solve imports defined in this block. + EXECUTE_IF_SET_IN_BITMAP (m_imports, 0, i, bi) + { + tree name = ssa_name (i); + + if (range_defined_in_block (r, name, bb)) + set_cache (r, name); + } + + if (at_exit ()) + return; + + // Solve imports that are exported to the next block. + edge e = find_edge (bb, next_bb ()); + EXECUTE_IF_SET_IN_BITMAP (m_imports, 0, i, bi) + { + tree name = ssa_name (i); + gori_compute &g = m_ranger.gori (); + bitmap exports = g.exports (bb); + + if (bitmap_bit_p (exports, i)) + { + if (g.outgoing_edge_range_p (r, e, name, *this)) + { + if (get_cache (cached_range, name)) + r.intersect (cached_range); + + set_cache (r, name); + if (DEBUG_SOLVER) + { + fprintf (dump_file, "outgoing_edge_range_p for "); + print_generic_expr (dump_file, name, TDF_SLIM); + fprintf (dump_file, " on edge %d->%d ", + e->src->index, e->dest->index); + fprintf (dump_file, "is "); + r.dump (dump_file); + fprintf (dump_file, "\n"); + } + } + } + } +} + +// Adjust all pointer imports in BB with non-null information. + +void +path_range_query::adjust_for_non_null_uses (basic_block bb) +{ + int_range_max r; + bitmap_iterator bi; + unsigned i; + + EXECUTE_IF_SET_IN_BITMAP (m_imports, 0, i, bi) + { + tree name = ssa_name (i); + + if (!POINTER_TYPE_P (TREE_TYPE (name))) + continue; + + if (get_cache (r, name)) + { + if (r.nonzero_p ()) + continue; + } + else + r.set_varying (TREE_TYPE (name)); + + if (m_non_null.adjust_range (r, name, bb)) + set_cache (r, name); + } +} + +// Precompute the ranges for IMPORTS along PATH. +// +// IMPORTS are the set of SSA names, any of which could potentially +// change the value of the final conditional in PATH. + +void +path_range_query::precompute_ranges (const vec<basic_block> &path, + const bitmap_head *imports) +{ + set_path (path); + m_imports = imports; + m_undefined_path = false; + + if (DEBUG_SOLVER) + { + fprintf (dump_file, "\npath_range_query: precompute_ranges for path: "); + for (unsigned i = path.length (); i > 0; --i) + { + basic_block bb = path[i - 1]; + fprintf (dump_file, "BB %d", bb->index); + if (i > 1) + fprintf (dump_file, ", "); + } + fprintf (dump_file, "\n"); + } + + while (1) + { + basic_block bb = curr_bb (); + + precompute_ranges_in_block (bb); + adjust_for_non_null_uses (bb); + + if (at_exit ()) + break; + + move_next (); + } + + if (DEBUG_SOLVER) + dump (dump_file); +} |