/* Loop distribution. Copyright (C) 2006-2013 Free Software Foundation, Inc. Contributed by Georges-Andre Silber and Sebastian Pop . 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 . */ /* This pass performs loop distribution: for example, the loop |DO I = 2, N | A(I) = B(I) + C | D(I) = A(I-1)*E |ENDDO is transformed to |DOALL I = 2, N | A(I) = B(I) + C |ENDDO | |DOALL I = 2, N | D(I) = A(I-1)*E |ENDDO This pass uses an RDG, Reduced Dependence Graph built on top of the data dependence relations. The RDG is then topologically sorted to obtain a map of information producers/consumers based on which it generates the new loops. */ #include "config.h" #include "system.h" #include "coretypes.h" #include "tree-flow.h" #include "cfgloop.h" #include "tree-chrec.h" #include "tree-data-ref.h" #include "tree-scalar-evolution.h" #include "tree-pass.h" enum partition_kind { PKIND_NORMAL, PKIND_REDUCTION, PKIND_MEMSET, PKIND_MEMCPY }; typedef struct partition_s { bitmap stmts; bool has_writes; enum partition_kind kind; /* data-references a kind != PKIND_NORMAL partition is about. */ data_reference_p main_dr; data_reference_p secondary_dr; } *partition_t; /* Allocate and initialize a partition from BITMAP. */ static partition_t partition_alloc (bitmap stmts) { partition_t partition = XCNEW (struct partition_s); partition->stmts = stmts ? stmts : BITMAP_ALLOC (NULL); partition->has_writes = false; partition->kind = PKIND_NORMAL; return partition; } /* Free PARTITION. */ static void partition_free (partition_t partition) { BITMAP_FREE (partition->stmts); free (partition); } /* Returns true if the partition can be generated as a builtin. */ static bool partition_builtin_p (partition_t partition) { return partition->kind > PKIND_REDUCTION; } /* Returns true if the partition has an writes. */ static bool partition_has_writes (partition_t partition) { return partition->has_writes; } /* If bit I is not set, it means that this node represents an operation that has already been performed, and that should not be performed again. This is the subgraph of remaining important computations that is passed to the DFS algorithm for avoiding to include several times the same stores in different loops. */ static bitmap remaining_stmts; /* A node of the RDG is marked in this bitmap when it has as a predecessor a node that writes to memory. */ static bitmap upstream_mem_writes; /* Returns true when DEF is an SSA_NAME defined in LOOP and used after the LOOP. */ static bool ssa_name_has_uses_outside_loop_p (tree def, loop_p loop) { imm_use_iterator imm_iter; use_operand_p use_p; FOR_EACH_IMM_USE_FAST (use_p, imm_iter, def) { gimple use_stmt = USE_STMT (use_p); if (!is_gimple_debug (use_stmt) && loop != loop_containing_stmt (use_stmt)) return true; } return false; } /* Returns true when STMT defines a scalar variable used after the loop LOOP. */ static bool stmt_has_scalar_dependences_outside_loop (loop_p loop, gimple stmt) { def_operand_p def_p; ssa_op_iter op_iter; if (gimple_code (stmt) == GIMPLE_PHI) return ssa_name_has_uses_outside_loop_p (gimple_phi_result (stmt), loop); FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, op_iter, SSA_OP_DEF) if (ssa_name_has_uses_outside_loop_p (DEF_FROM_PTR (def_p), loop)) return true; return false; } /* Return a copy of LOOP placed before LOOP. */ static struct loop * copy_loop_before (struct loop *loop) { struct loop *res; edge preheader = loop_preheader_edge (loop); initialize_original_copy_tables (); res = slpeel_tree_duplicate_loop_to_edge_cfg (loop, preheader); gcc_assert (res != NULL); free_original_copy_tables (); delete_update_ssa (); return res; } /* Creates an empty basic block after LOOP. */ static void create_bb_after_loop (struct loop *loop) { edge exit = single_exit (loop); if (!exit) return; split_edge (exit); } /* Generate code for PARTITION from the code in LOOP. The loop is copied when COPY_P is true. All the statements not flagged in the PARTITION bitmap are removed from the loop or from its copy. The statements are indexed in sequence inside a basic block, and the basic blocks of a loop are taken in dom order. */ static void generate_loops_for_partition (struct loop *loop, partition_t partition, bool copy_p) { unsigned i, x; gimple_stmt_iterator bsi; basic_block *bbs; if (copy_p) { loop = copy_loop_before (loop); gcc_assert (loop != NULL); create_preheader (loop, CP_SIMPLE_PREHEADERS); create_bb_after_loop (loop); } /* Remove stmts not in the PARTITION bitmap. The order in which we visit the phi nodes and the statements is exactly as in stmts_from_loop. */ bbs = get_loop_body_in_dom_order (loop); if (MAY_HAVE_DEBUG_STMTS) for (x = 0, i = 0; i < loop->num_nodes; i++) { basic_block bb = bbs[i]; for (bsi = gsi_start_phis (bb); !gsi_end_p (bsi); gsi_next (&bsi)) if (!bitmap_bit_p (partition->stmts, x++)) reset_debug_uses (gsi_stmt (bsi)); for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi)) { gimple stmt = gsi_stmt (bsi); if (gimple_code (stmt) != GIMPLE_LABEL && !is_gimple_debug (stmt) && !bitmap_bit_p (partition->stmts, x++)) reset_debug_uses (stmt); } } for (x = 0, i = 0; i < loop->num_nodes; i++) { basic_block bb = bbs[i]; for (bsi = gsi_start_phis (bb); !gsi_end_p (bsi);) if (!bitmap_bit_p (partition->stmts, x++)) { gimple phi = gsi_stmt (bsi); if (virtual_operand_p (gimple_phi_result (phi))) mark_virtual_phi_result_for_renaming (phi); remove_phi_node (&bsi, true); } else gsi_next (&bsi); for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi);) { gimple stmt = gsi_stmt (bsi); if (gimple_code (stmt) != GIMPLE_LABEL && !is_gimple_debug (stmt) && !bitmap_bit_p (partition->stmts, x++)) { unlink_stmt_vdef (stmt); gsi_remove (&bsi, true); release_defs (stmt); } else gsi_next (&bsi); } } free (bbs); } /* Build the size argument for a memory operation call. */ static tree build_size_arg_loc (location_t loc, data_reference_p dr, tree nb_iter) { tree size; size = fold_build2_loc (loc, MULT_EXPR, sizetype, fold_convert_loc (loc, sizetype, nb_iter), TYPE_SIZE_UNIT (TREE_TYPE (DR_REF (dr)))); return fold_convert_loc (loc, size_type_node, size); } /* Build an address argument for a memory operation call. */ static tree build_addr_arg_loc (location_t loc, data_reference_p dr, tree nb_bytes) { tree addr_base; addr_base = size_binop_loc (loc, PLUS_EXPR, DR_OFFSET (dr), DR_INIT (dr)); addr_base = fold_convert_loc (loc, sizetype, addr_base); /* Test for a negative stride, iterating over every element. */ if (tree_int_cst_sgn (DR_STEP (dr)) == -1) { addr_base = size_binop_loc (loc, MINUS_EXPR, addr_base, fold_convert_loc (loc, sizetype, nb_bytes)); addr_base = size_binop_loc (loc, PLUS_EXPR, addr_base, TYPE_SIZE_UNIT (TREE_TYPE (DR_REF (dr)))); } return fold_build_pointer_plus_loc (loc, DR_BASE_ADDRESS (dr), addr_base); } /* Generate a call to memset for PARTITION in LOOP. */ static void generate_memset_builtin (struct loop *loop, partition_t partition) { gimple_stmt_iterator gsi; gimple stmt, fn_call; tree nb_iter, mem, fn, nb_bytes; location_t loc; tree val; stmt = DR_STMT (partition->main_dr); loc = gimple_location (stmt); if (gimple_bb (stmt) == loop->latch) nb_iter = number_of_latch_executions (loop); else nb_iter = number_of_exit_cond_executions (loop); /* The new statements will be placed before LOOP. */ gsi = gsi_last_bb (loop_preheader_edge (loop)->src); nb_bytes = build_size_arg_loc (loc, partition->main_dr, nb_iter); nb_bytes = force_gimple_operand_gsi (&gsi, nb_bytes, true, NULL_TREE, false, GSI_CONTINUE_LINKING); mem = build_addr_arg_loc (loc, partition->main_dr, nb_bytes); mem = force_gimple_operand_gsi (&gsi, mem, true, NULL_TREE, false, GSI_CONTINUE_LINKING); /* This exactly matches the pattern recognition in classify_partition. */ val = gimple_assign_rhs1 (stmt); if (integer_zerop (val) || real_zerop (val) || TREE_CODE (val) == CONSTRUCTOR) val = integer_zero_node; else if (integer_all_onesp (val)) val = build_int_cst (integer_type_node, -1); else { if (TREE_CODE (val) == INTEGER_CST) val = fold_convert (integer_type_node, val); else if (!useless_type_conversion_p (integer_type_node, TREE_TYPE (val))) { gimple cstmt; tree tem = make_ssa_name (integer_type_node, NULL); cstmt = gimple_build_assign_with_ops (NOP_EXPR, tem, val, NULL_TREE); gsi_insert_after (&gsi, cstmt, GSI_CONTINUE_LINKING); val = tem; } } fn = build_fold_addr_expr (builtin_decl_implicit (BUILT_IN_MEMSET)); fn_call = gimple_build_call (fn, 3, mem, val, nb_bytes); gsi_insert_after (&gsi, fn_call, GSI_CONTINUE_LINKING); if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "generated memset"); if (integer_zerop (val)) fprintf (dump_file, " zero\n"); else if (integer_all_onesp (val)) fprintf (dump_file, " minus one\n"); else fprintf (dump_file, "\n"); } } /* Generate a call to memcpy for PARTITION in LOOP. */ static void generate_memcpy_builtin (struct loop *loop, partition_t partition) { gimple_stmt_iterator gsi; gimple stmt, fn_call; tree nb_iter, dest, src, fn, nb_bytes; location_t loc; enum built_in_function kind; stmt = DR_STMT (partition->main_dr); loc = gimple_location (stmt); if (gimple_bb (stmt) == loop->latch) nb_iter = number_of_latch_executions (loop); else nb_iter = number_of_exit_cond_executions (loop); /* The new statements will be placed before LOOP. */ gsi = gsi_last_bb (loop_preheader_edge (loop)->src); nb_bytes = build_size_arg_loc (loc, partition->main_dr, nb_iter); nb_bytes = force_gimple_operand_gsi (&gsi, nb_bytes, true, NULL_TREE, false, GSI_CONTINUE_LINKING); dest = build_addr_arg_loc (loc, partition->main_dr, nb_bytes); src = build_addr_arg_loc (loc, partition->secondary_dr, nb_bytes); if (ptr_derefs_may_alias_p (dest, src)) kind = BUILT_IN_MEMMOVE; else kind = BUILT_IN_MEMCPY; dest = force_gimple_operand_gsi (&gsi, dest, true, NULL_TREE, false, GSI_CONTINUE_LINKING); src = force_gimple_operand_gsi (&gsi, src, true, NULL_TREE, false, GSI_CONTINUE_LINKING); fn = build_fold_addr_expr (builtin_decl_implicit (kind)); fn_call = gimple_build_call (fn, 3, dest, src, nb_bytes); gsi_insert_after (&gsi, fn_call, GSI_CONTINUE_LINKING); if (dump_file && (dump_flags & TDF_DETAILS)) { if (kind == BUILT_IN_MEMCPY) fprintf (dump_file, "generated memcpy\n"); else fprintf (dump_file, "generated memmove\n"); } } /* Remove and destroy the loop LOOP. */ static void destroy_loop (struct loop *loop) { unsigned nbbs = loop->num_nodes; edge exit = single_exit (loop); basic_block src = loop_preheader_edge (loop)->src, dest = exit->dest; basic_block *bbs; unsigned i; bbs = get_loop_body_in_dom_order (loop); redirect_edge_pred (exit, src); exit->flags &= ~(EDGE_TRUE_VALUE|EDGE_FALSE_VALUE); exit->flags |= EDGE_FALLTHRU; cancel_loop_tree (loop); rescan_loop_exit (exit, false, true); for (i = 0; i < nbbs; i++) { /* We have made sure to not leave any dangling uses of SSA names defined in the loop. With the exception of virtuals. Make sure we replace all uses of virtual defs that will remain outside of the loop with the bare symbol as delete_basic_block will release them. */ gimple_stmt_iterator gsi; for (gsi = gsi_start_phis (bbs[i]); !gsi_end_p (gsi); gsi_next (&gsi)) { gimple phi = gsi_stmt (gsi); if (virtual_operand_p (gimple_phi_result (phi))) mark_virtual_phi_result_for_renaming (phi); } for (gsi = gsi_start_bb (bbs[i]); !gsi_end_p (gsi); gsi_next (&gsi)) { gimple stmt = gsi_stmt (gsi); tree vdef = gimple_vdef (stmt); if (vdef && TREE_CODE (vdef) == SSA_NAME) mark_virtual_operand_for_renaming (vdef); } delete_basic_block (bbs[i]); } free (bbs); set_immediate_dominator (CDI_DOMINATORS, dest, recompute_dominator (CDI_DOMINATORS, dest)); } /* Generates code for PARTITION. */ static void generate_code_for_partition (struct loop *loop, partition_t partition, bool copy_p) { switch (partition->kind) { case PKIND_MEMSET: generate_memset_builtin (loop, partition); /* If this is the last partition for which we generate code, we have to destroy the loop. */ if (!copy_p) destroy_loop (loop); break; case PKIND_MEMCPY: generate_memcpy_builtin (loop, partition); /* If this is the last partition for which we generate code, we have to destroy the loop. */ if (!copy_p) destroy_loop (loop); break; case PKIND_REDUCTION: /* Reductions all have to be in the last partition. */ gcc_assert (!copy_p); case PKIND_NORMAL: generate_loops_for_partition (loop, partition, copy_p); break; default: gcc_unreachable (); } } /* Returns true if the node V of RDG cannot be recomputed. */ static bool rdg_cannot_recompute_vertex_p (struct graph *rdg, int v) { if (RDG_MEM_WRITE_STMT (rdg, v)) return true; return false; } /* Returns true when the vertex V has already been generated in the current partition (V is in PROCESSED), or when V belongs to another partition and cannot be recomputed (V is not in REMAINING_STMTS). */ static inline bool already_processed_vertex_p (bitmap processed, int v) { return (bitmap_bit_p (processed, v) || !bitmap_bit_p (remaining_stmts, v)); } /* Returns NULL when there is no anti-dependence or output-dependence among the successors of vertex V, otherwise returns the edge with the dependency. */ static struct graph_edge * has_anti_or_output_dependence (struct vertex *v) { struct graph_edge *e; if (v->succ) for (e = v->succ; e; e = e->succ_next) if (RDGE_TYPE (e) == anti_dd || RDGE_TYPE (e) == output_dd) return e; return NULL; } /* Returns true when V has an anti-dependence edge among its successors. */ static bool predecessor_has_mem_write (struct graph *rdg, struct vertex *v) { struct graph_edge *e; if (v->pred) for (e = v->pred; e; e = e->pred_next) if (bitmap_bit_p (upstream_mem_writes, e->src) /* Don't consider flow channels: a write to memory followed by a read from memory. These channels allow the split of the RDG in different partitions. */ && !RDG_MEM_WRITE_STMT (rdg, e->src)) return true; return false; } /* Initializes the upstream_mem_writes bitmap following the information from RDG. */ static void mark_nodes_having_upstream_mem_writes (struct graph *rdg) { int v, x; bitmap seen = BITMAP_ALLOC (NULL); for (v = rdg->n_vertices - 1; v >= 0; v--) if (!bitmap_bit_p (seen, v)) { unsigned i; vec nodes; nodes.create (3); graphds_dfs (rdg, &v, 1, &nodes, false, NULL); FOR_EACH_VEC_ELT (nodes, i, x) { if (!bitmap_set_bit (seen, x)) continue; if (RDG_MEM_WRITE_STMT (rdg, x) || predecessor_has_mem_write (rdg, &(rdg->vertices[x])) /* In anti dependences the read should occur before the write, this is why both the read and the write should be placed in the same partition. In output dependences the writes order need to be preserved. */ || has_anti_or_output_dependence (&(rdg->vertices[x]))) bitmap_set_bit (upstream_mem_writes, x); } nodes.release (); } } /* Returns true when vertex u has a memory write node as a predecessor in RDG. */ static bool has_upstream_mem_writes (int u) { return bitmap_bit_p (upstream_mem_writes, u); } static void rdg_flag_vertex_and_dependent (struct graph *, int, partition_t, bitmap, bitmap); /* Flag the uses of U stopping following the information from upstream_mem_writes. */ static void rdg_flag_uses (struct graph *rdg, int u, partition_t partition, bitmap loops, bitmap processed) { use_operand_p use_p; struct vertex *x = &(rdg->vertices[u]); gimple stmt = RDGV_STMT (x); struct graph_edge *anti_dep = has_anti_or_output_dependence (x); /* Keep in the same partition the destination of an antidependence, because this is a store to the exact same location. Putting this in another partition is bad for cache locality. */ if (anti_dep) { int v = anti_dep->dest; if (!already_processed_vertex_p (processed, v)) rdg_flag_vertex_and_dependent (rdg, v, partition, loops, processed); } if (gimple_code (stmt) != GIMPLE_PHI) { if ((use_p = gimple_vuse_op (stmt)) != NULL_USE_OPERAND_P) { tree use = USE_FROM_PTR (use_p); if (TREE_CODE (use) == SSA_NAME && !SSA_NAME_IS_DEFAULT_DEF (use)) { gimple def_stmt = SSA_NAME_DEF_STMT (use); int v = rdg_vertex_for_stmt (rdg, def_stmt); if (v >= 0 && !already_processed_vertex_p (processed, v)) rdg_flag_vertex_and_dependent (rdg, v, partition, loops, processed); } } } if (is_gimple_assign (stmt) && has_upstream_mem_writes (u)) { tree op0 = gimple_assign_lhs (stmt); /* Scalar channels don't have enough space for transmitting data between tasks, unless we add more storage by privatizing. */ if (is_gimple_reg (op0)) { use_operand_p use_p; imm_use_iterator iter; FOR_EACH_IMM_USE_FAST (use_p, iter, op0) { int v = rdg_vertex_for_stmt (rdg, USE_STMT (use_p)); if (!already_processed_vertex_p (processed, v)) rdg_flag_vertex_and_dependent (rdg, v, partition, loops, processed); } } } } /* Flag V from RDG as part of PARTITION, and also flag its loop number in LOOPS. */ static void rdg_flag_vertex (struct graph *rdg, int v, partition_t partition, bitmap loops) { struct loop *loop; if (!bitmap_set_bit (partition->stmts, v)) return; loop = loop_containing_stmt (RDG_STMT (rdg, v)); bitmap_set_bit (loops, loop->num); if (rdg_cannot_recompute_vertex_p (rdg, v)) { partition->has_writes = true; bitmap_clear_bit (remaining_stmts, v); } } /* Flag in the bitmap PARTITION the vertex V and all its predecessors. Also flag their loop number in LOOPS. */ static void rdg_flag_vertex_and_dependent (struct graph *rdg, int v, partition_t partition, bitmap loops, bitmap processed) { unsigned i; vec nodes; nodes.create (3); int x; bitmap_set_bit (processed, v); rdg_flag_uses (rdg, v, partition, loops, processed); graphds_dfs (rdg, &v, 1, &nodes, false, remaining_stmts); rdg_flag_vertex (rdg, v, partition, loops); FOR_EACH_VEC_ELT (nodes, i, x) if (!already_processed_vertex_p (processed, x)) rdg_flag_vertex_and_dependent (rdg, x, partition, loops, processed); nodes.release (); } /* Initialize CONDS with all the condition statements from the basic blocks of LOOP. */ static void collect_condition_stmts (struct loop *loop, vec *conds) { unsigned i; edge e; vec exits = get_loop_exit_edges (loop); FOR_EACH_VEC_ELT (exits, i, e) { gimple cond = last_stmt (e->src); if (cond) conds->safe_push (cond); } exits.release (); } /* Add to PARTITION all the exit condition statements for LOOPS together with all their dependent statements determined from RDG. */ static void rdg_flag_loop_exits (struct graph *rdg, bitmap loops, partition_t partition, bitmap processed) { unsigned i; bitmap_iterator bi; vec conds; conds.create (3); EXECUTE_IF_SET_IN_BITMAP (loops, 0, i, bi) collect_condition_stmts (get_loop (i), &conds); while (!conds.is_empty ()) { gimple cond = conds.pop (); int v = rdg_vertex_for_stmt (rdg, cond); bitmap new_loops = BITMAP_ALLOC (NULL); if (!already_processed_vertex_p (processed, v)) rdg_flag_vertex_and_dependent (rdg, v, partition, new_loops, processed); EXECUTE_IF_SET_IN_BITMAP (new_loops, 0, i, bi) if (bitmap_set_bit (loops, i)) collect_condition_stmts (get_loop (i), &conds); BITMAP_FREE (new_loops); } conds.release (); } /* Returns a bitmap in which all the statements needed for computing the strongly connected component C of the RDG are flagged, also including the loop exit conditions. */ static partition_t build_rdg_partition_for_component (struct graph *rdg, rdgc c) { int i, v; partition_t partition = partition_alloc (NULL); bitmap loops = BITMAP_ALLOC (NULL); bitmap processed = BITMAP_ALLOC (NULL); FOR_EACH_VEC_ELT (c->vertices, i, v) if (!already_processed_vertex_p (processed, v)) rdg_flag_vertex_and_dependent (rdg, v, partition, loops, processed); rdg_flag_loop_exits (rdg, loops, partition, processed); BITMAP_FREE (processed); BITMAP_FREE (loops); return partition; } /* Free memory for COMPONENTS. */ static void free_rdg_components (vec components) { int i; rdgc x; FOR_EACH_VEC_ELT (components, i, x) { x->vertices.release (); free (x); } components.release (); } /* Build the COMPONENTS vector with the strongly connected components of RDG in which the STARTING_VERTICES occur. */ static void rdg_build_components (struct graph *rdg, vec starting_vertices, vec *components) { int i, v; bitmap saved_components = BITMAP_ALLOC (NULL); int n_components = graphds_scc (rdg, NULL); /* ??? Macros cannot process template types with more than one argument, so we need this typedef. */ typedef vec vec_int_heap; vec *all_components = XNEWVEC (vec_int_heap, n_components); for (i = 0; i < n_components; i++) all_components[i].create (3); for (i = 0; i < rdg->n_vertices; i++) all_components[rdg->vertices[i].component].safe_push (i); FOR_EACH_VEC_ELT (starting_vertices, i, v) { int c = rdg->vertices[v].component; if (bitmap_set_bit (saved_components, c)) { rdgc x = XCNEW (struct rdg_component); x->num = c; x->vertices = all_components[c]; components->safe_push (x); } } for (i = 0; i < n_components; i++) if (!bitmap_bit_p (saved_components, i)) all_components[i].release (); free (all_components); BITMAP_FREE (saved_components); } /* Classifies the builtin kind we can generate for PARTITION of RDG and LOOP. For the moment we detect only the memset zero pattern. */ static void classify_partition (loop_p loop, struct graph *rdg, partition_t partition) { bitmap_iterator bi; unsigned i; tree nb_iter; data_reference_p single_load, single_store; bool volatiles_p = false; partition->kind = PKIND_NORMAL; partition->main_dr = NULL; partition->secondary_dr = NULL; EXECUTE_IF_SET_IN_BITMAP (partition->stmts, 0, i, bi) { gimple stmt = RDG_STMT (rdg, i); if (gimple_has_volatile_ops (stmt)) volatiles_p = true; /* If the stmt has uses outside of the loop fail. ??? If the stmt is generated in another partition that is not created as builtin we can ignore this. */ if (stmt_has_scalar_dependences_outside_loop (loop, stmt)) { if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, "not generating builtin, partition has " "scalar uses outside of the loop\n"); partition->kind = PKIND_REDUCTION; return; } } /* Perform general partition disqualification for builtins. */ if (volatiles_p || !flag_tree_loop_distribute_patterns) return; nb_iter = number_of_exit_cond_executions (loop); if (!nb_iter || nb_iter == chrec_dont_know) return; /* Detect memset and memcpy. */ single_load = NULL; single_store = NULL; EXECUTE_IF_SET_IN_BITMAP (partition->stmts, 0, i, bi) { gimple stmt = RDG_STMT (rdg, i); data_reference_p dr; unsigned j; if (gimple_code (stmt) == GIMPLE_PHI) continue; /* Any scalar stmts are ok. */ if (!gimple_vuse (stmt)) continue; /* Otherwise just regular loads/stores. */ if (!gimple_assign_single_p (stmt)) return; /* But exactly one store and/or load. */ for (j = 0; RDG_DATAREFS (rdg, i).iterate (j, &dr); ++j) { if (DR_IS_READ (dr)) { if (single_load != NULL) return; single_load = dr; } else { if (single_store != NULL) return; single_store = dr; } } } if (single_store && !single_load) { gimple stmt = DR_STMT (single_store); tree rhs = gimple_assign_rhs1 (stmt); if (!(integer_zerop (rhs) || real_zerop (rhs) || (TREE_CODE (rhs) == CONSTRUCTOR && !TREE_CLOBBER_P (rhs)) || ((integer_all_onesp (rhs) || (INTEGRAL_TYPE_P (TREE_TYPE (rhs)) && (TYPE_MODE (TREE_TYPE (rhs)) == TYPE_MODE (unsigned_char_type_node)))) /* For stores of a non-zero value require that the precision of the value matches its actual size. */ && (TYPE_PRECISION (TREE_TYPE (rhs)) == GET_MODE_BITSIZE (TYPE_MODE (TREE_TYPE (rhs))))))) return; if (TREE_CODE (rhs) == SSA_NAME && !SSA_NAME_IS_DEFAULT_DEF (rhs) && flow_bb_inside_loop_p (loop, gimple_bb (SSA_NAME_DEF_STMT (rhs)))) return; if (!adjacent_dr_p (single_store)) return; partition->kind = PKIND_MEMSET; partition->main_dr = single_store; } else if (single_store && single_load) { gimple store = DR_STMT (single_store); gimple load = DR_STMT (single_load); /* Direct aggregate copy or via an SSA name temporary. */ if (load != store && gimple_assign_lhs (load) != gimple_assign_rhs1 (store)) return; if (!adjacent_dr_p (single_store) || !adjacent_dr_p (single_load) || !operand_equal_p (DR_STEP (single_store), DR_STEP (single_load), 0)) return; /* Now check that if there is a dependence this dependence is of a suitable form for memmove. */ vec loops = vNULL; ddr_p ddr; loops.safe_push (loop); ddr = initialize_data_dependence_relation (single_load, single_store, loops); compute_affine_dependence (ddr, loop); if (DDR_ARE_DEPENDENT (ddr) == chrec_dont_know) { free_dependence_relation (ddr); loops.release (); return; } if (DDR_ARE_DEPENDENT (ddr) != chrec_known) { if (DDR_NUM_DIST_VECTS (ddr) == 0) { free_dependence_relation (ddr); loops.release (); return; } lambda_vector dist_v; FOR_EACH_VEC_ELT (DDR_DIST_VECTS (ddr), i, dist_v) { int dist = dist_v[index_in_loop_nest (loop->num, DDR_LOOP_NEST (ddr))]; if (dist > 0 && !DDR_REVERSED_P (ddr)) { free_dependence_relation (ddr); loops.release (); return; } } } free_dependence_relation (ddr); loops.release (); partition->kind = PKIND_MEMCPY; partition->main_dr = single_store; partition->secondary_dr = single_load; } } /* For a data reference REF, return the declaration of its base address or NULL_TREE if the base is not determined. */ static tree ref_base_address (data_reference_p dr) { tree base_address = DR_BASE_ADDRESS (dr); if (base_address && TREE_CODE (base_address) == ADDR_EXPR) return TREE_OPERAND (base_address, 0); return base_address; } /* Returns true when PARTITION1 and PARTITION2 have similar memory accesses in RDG. */ static bool similar_memory_accesses (struct graph *rdg, partition_t partition1, partition_t partition2) { unsigned i, j, k, l; bitmap_iterator bi, bj; data_reference_p ref1, ref2; /* First check whether in the intersection of the two partitions are any loads or stores. Common loads are the situation that happens most often. */ EXECUTE_IF_AND_IN_BITMAP (partition1->stmts, partition2->stmts, 0, i, bi) if (RDG_MEM_WRITE_STMT (rdg, i) || RDG_MEM_READS_STMT (rdg, i)) return true; /* Then check all data-references against each other. */ EXECUTE_IF_SET_IN_BITMAP (partition1->stmts, 0, i, bi) if (RDG_MEM_WRITE_STMT (rdg, i) || RDG_MEM_READS_STMT (rdg, i)) EXECUTE_IF_SET_IN_BITMAP (partition2->stmts, 0, j, bj) if (RDG_MEM_WRITE_STMT (rdg, j) || RDG_MEM_READS_STMT (rdg, j)) { FOR_EACH_VEC_ELT (RDG_DATAREFS (rdg, i), k, ref1) { tree base1 = ref_base_address (ref1); if (base1) FOR_EACH_VEC_ELT (RDG_DATAREFS (rdg, j), l, ref2) if (base1 == ref_base_address (ref2)) return true; } } return false; } /* Aggregate several components into a useful partition that is registered in the PARTITIONS vector. Partitions will be distributed in different loops. */ static void rdg_build_partitions (struct graph *rdg, vec components, vec *other_stores, vec *partitions, bitmap processed) { int i; rdgc x; partition_t partition = partition_alloc (NULL); FOR_EACH_VEC_ELT (components, i, x) { partition_t np; int v = x->vertices[0]; if (bitmap_bit_p (processed, v)) continue; np = build_rdg_partition_for_component (rdg, x); bitmap_ior_into (partition->stmts, np->stmts); partition->has_writes = partition_has_writes (np); bitmap_ior_into (processed, np->stmts); partition_free (np); if (partition_has_writes (partition)) { if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "ldist useful partition:\n"); dump_bitmap (dump_file, partition->stmts); } partitions->safe_push (partition); partition = partition_alloc (NULL); } } /* Add the nodes from the RDG that were not marked as processed, and that are used outside the current loop. These are scalar computations that are not yet part of previous partitions. */ for (i = 0; i < rdg->n_vertices; i++) if (!bitmap_bit_p (processed, i) && rdg_defs_used_in_other_loops_p (rdg, i)) other_stores->safe_push (i); /* If there are still statements left in the OTHER_STORES array, create other components and partitions with these stores and their dependences. */ if (other_stores->length () > 0) { vec comps; comps.create (3); vec foo; foo.create (3); rdg_build_components (rdg, *other_stores, &comps); rdg_build_partitions (rdg, comps, &foo, partitions, processed); foo.release (); free_rdg_components (comps); } /* If there is something left in the last partition, save it. */ if (bitmap_count_bits (partition->stmts) > 0) partitions->safe_push (partition); else partition_free (partition); } /* Dump to FILE the PARTITIONS. */ static void dump_rdg_partitions (FILE *file, vec partitions) { int i; partition_t partition; FOR_EACH_VEC_ELT (partitions, i, partition) debug_bitmap_file (file, partition->stmts); } /* Debug PARTITIONS. */ extern void debug_rdg_partitions (vec ); DEBUG_FUNCTION void debug_rdg_partitions (vec partitions) { dump_rdg_partitions (stderr, partitions); } /* Returns the number of read and write operations in the RDG. */ static int number_of_rw_in_rdg (struct graph *rdg) { int i, res = 0; for (i = 0; i < rdg->n_vertices; i++) { if (RDG_MEM_WRITE_STMT (rdg, i)) ++res; if (RDG_MEM_READS_STMT (rdg, i)) ++res; } return res; } /* Returns the number of read and write operations in a PARTITION of the RDG. */ static int number_of_rw_in_partition (struct graph *rdg, partition_t partition) { int res = 0; unsigned i; bitmap_iterator ii; EXECUTE_IF_SET_IN_BITMAP (partition->stmts, 0, i, ii) { if (RDG_MEM_WRITE_STMT (rdg, i)) ++res; if (RDG_MEM_READS_STMT (rdg, i)) ++res; } return res; } /* Returns true when one of the PARTITIONS contains all the read or write operations of RDG. */ static bool partition_contains_all_rw (struct graph *rdg, vec partitions) { int i; partition_t partition; int nrw = number_of_rw_in_rdg (rdg); FOR_EACH_VEC_ELT (partitions, i, partition) if (nrw == number_of_rw_in_partition (rdg, partition)) return true; return false; } /* Generate code from STARTING_VERTICES in RDG. Returns the number of distributed loops. */ static int ldist_gen (struct loop *loop, struct graph *rdg, vec starting_vertices) { int i, nbp; vec components; components.create (3); vec partitions; partitions.create (3); vec other_stores; other_stores.create (3); partition_t partition; bitmap processed = BITMAP_ALLOC (NULL); bool any_builtin; remaining_stmts = BITMAP_ALLOC (NULL); upstream_mem_writes = BITMAP_ALLOC (NULL); for (i = 0; i < rdg->n_vertices; i++) { bitmap_set_bit (remaining_stmts, i); /* Save in OTHER_STORES all the memory writes that are not in STARTING_VERTICES. */ if (RDG_MEM_WRITE_STMT (rdg, i)) { int v; unsigned j; bool found = false; FOR_EACH_VEC_ELT (starting_vertices, j, v) if (i == v) { found = true; break; } if (!found) other_stores.safe_push (i); } } mark_nodes_having_upstream_mem_writes (rdg); rdg_build_components (rdg, starting_vertices, &components); rdg_build_partitions (rdg, components, &other_stores, &partitions, processed); BITMAP_FREE (processed); any_builtin = false; FOR_EACH_VEC_ELT (partitions, i, partition) { classify_partition (loop, rdg, partition); any_builtin |= partition_builtin_p (partition); } /* If we are only distributing patterns fuse all partitions that were not properly classified as builtins. Else fuse partitions with similar memory accesses. */ if (!flag_tree_loop_distribution) { partition_t into; /* If we did not detect any builtin simply bail out. */ if (!any_builtin) { nbp = 0; goto ldist_done; } /* Only fuse adjacent non-builtin partitions, see PR53616. ??? Use dependence information to improve partition ordering. */ i = 0; do { for (; partitions.iterate (i, &into); ++i) if (!partition_builtin_p (into)) break; for (++i; partitions.iterate (i, &partition); ++i) if (!partition_builtin_p (partition)) { bitmap_ior_into (into->stmts, partition->stmts); if (partition->kind == PKIND_REDUCTION) into->kind = PKIND_REDUCTION; partitions.ordered_remove (i); partition_free (partition); i--; } else break; } while ((unsigned) i < partitions.length ()); } else { partition_t into; int j; for (i = 0; partitions.iterate (i, &into); ++i) { if (partition_builtin_p (into)) continue; for (j = i + 1; partitions.iterate (j, &partition); ++j) { if (!partition_builtin_p (partition) /* ??? The following is horribly inefficient, we are re-computing and analyzing data-references of the stmts in the partitions all the time. */ && similar_memory_accesses (rdg, into, partition)) { if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "fusing partitions\n"); dump_bitmap (dump_file, into->stmts); dump_bitmap (dump_file, partition->stmts); fprintf (dump_file, "because they have similar " "memory accesses\n"); } bitmap_ior_into (into->stmts, partition->stmts); if (partition->kind == PKIND_REDUCTION) into->kind = PKIND_REDUCTION; partitions.ordered_remove (j); partition_free (partition); j--; } } } } /* Fuse all reduction partitions into the last. */ if (partitions.length () > 1) { partition_t into = partitions.last (); for (i = partitions.length () - 2; i >= 0; --i) { partition_t what = partitions[i]; if (what->kind == PKIND_REDUCTION) { if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "fusing partitions\n"); dump_bitmap (dump_file, into->stmts); dump_bitmap (dump_file, what->stmts); fprintf (dump_file, "because the latter has reductions\n"); } bitmap_ior_into (into->stmts, what->stmts); into->kind = PKIND_REDUCTION; partitions.ordered_remove (i); partition_free (what); } } } nbp = partitions.length (); if (nbp == 0 || (nbp == 1 && !partition_builtin_p (partitions[0])) || (nbp > 1 && partition_contains_all_rw (rdg, partitions))) { nbp = 0; goto ldist_done; } if (dump_file && (dump_flags & TDF_DETAILS)) dump_rdg_partitions (dump_file, partitions); FOR_EACH_VEC_ELT (partitions, i, partition) generate_code_for_partition (loop, partition, i < nbp - 1); ldist_done: BITMAP_FREE (remaining_stmts); BITMAP_FREE (upstream_mem_writes); FOR_EACH_VEC_ELT (partitions, i, partition) partition_free (partition); other_stores.release (); partitions.release (); free_rdg_components (components); return nbp; } /* Distributes the code from LOOP in such a way that producer statements are placed before consumer statements. When STMTS is NULL, performs the maximal distribution, if STMTS is not NULL, tries to separate only these statements from the LOOP's body. Returns the number of distributed loops. */ static int distribute_loop (struct loop *loop, vec stmts) { int res = 0; struct graph *rdg; gimple s; unsigned i; vec vertices; vec dependence_relations; vec datarefs; vec loop_nest; datarefs.create (10); dependence_relations.create (100); loop_nest.create (3); rdg = build_rdg (loop, &loop_nest, &dependence_relations, &datarefs); if (!rdg) { if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, "FIXME: Loop %d not distributed: failed to build the RDG.\n", loop->num); free_dependence_relations (dependence_relations); free_data_refs (datarefs); loop_nest.release (); return res; } vertices.create (3); if (dump_file && (dump_flags & TDF_DETAILS)) dump_rdg (dump_file, rdg); FOR_EACH_VEC_ELT (stmts, i, s) { int v = rdg_vertex_for_stmt (rdg, s); if (v >= 0) { vertices.safe_push (v); if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, "ldist asked to generate code for vertex %d\n", v); } } res = ldist_gen (loop, rdg, vertices); vertices.release (); free_rdg (rdg); free_dependence_relations (dependence_relations); free_data_refs (datarefs); loop_nest.release (); return res; } /* Distribute all loops in the current function. */ static unsigned int tree_loop_distribution (void) { struct loop *loop; loop_iterator li; bool changed = false; basic_block bb; FOR_ALL_BB (bb) { gimple_stmt_iterator gsi; for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) gimple_set_uid (gsi_stmt (gsi), -1); for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) gimple_set_uid (gsi_stmt (gsi), -1); } /* We can at the moment only distribute non-nested loops, thus restrict walking to innermost loops. */ FOR_EACH_LOOP (li, loop, LI_ONLY_INNERMOST) { vec work_list = vNULL; basic_block *bbs; int num = loop->num; int nb_generated_loops = 0; unsigned int i; /* If the loop doesn't have a single exit we will fail anyway, so do that early. */ if (!single_exit (loop)) continue; /* Only optimize hot loops. */ if (!optimize_loop_for_speed_p (loop)) continue; /* Only distribute loops with a header and latch for now. */ if (loop->num_nodes > 2) continue; /* Initialize the worklist with stmts we seed the partitions with. */ bbs = get_loop_body_in_dom_order (loop); for (i = 0; i < loop->num_nodes; ++i) { gimple_stmt_iterator gsi; for (gsi = gsi_start_bb (bbs[i]); !gsi_end_p (gsi); gsi_next (&gsi)) { gimple stmt = gsi_stmt (gsi); /* Distribute stmts which have defs that are used outside of the loop. */ if (stmt_has_scalar_dependences_outside_loop (loop, stmt)) ; /* Otherwise only distribute stores for now. */ else if (!gimple_assign_single_p (stmt) || is_gimple_reg (gimple_assign_lhs (stmt))) continue; work_list.safe_push (stmt); } } free (bbs); if (work_list.length () > 0) nb_generated_loops = distribute_loop (loop, work_list); if (nb_generated_loops > 0) changed = true; if (dump_file && (dump_flags & TDF_DETAILS)) { if (nb_generated_loops > 1) fprintf (dump_file, "Loop %d distributed: split to %d loops.\n", num, nb_generated_loops); else fprintf (dump_file, "Loop %d is the same.\n", num); } work_list.release (); } if (changed) { mark_virtual_operands_for_renaming (cfun); rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa); } #ifdef ENABLE_CHECKING verify_loop_structure (); #endif return 0; } static bool gate_tree_loop_distribution (void) { return flag_tree_loop_distribution || flag_tree_loop_distribute_patterns; } struct gimple_opt_pass pass_loop_distribution = { { GIMPLE_PASS, "ldist", /* name */ OPTGROUP_LOOP, /* optinfo_flags */ gate_tree_loop_distribution, /* gate */ tree_loop_distribution, /* execute */ NULL, /* sub */ NULL, /* next */ 0, /* static_pass_number */ TV_TREE_LOOP_DISTRIBUTION, /* tv_id */ PROP_cfg | PROP_ssa, /* properties_required */ 0, /* properties_provided */ 0, /* properties_destroyed */ 0, /* todo_flags_start */ TODO_ggc_collect | TODO_verify_ssa /* todo_flags_finish */ } };