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Diffstat (limited to 'gcc/tree-loop-distribution.c')
| -rw-r--r-- | gcc/tree-loop-distribution.c | 1173 |
1 files changed, 1173 insertions, 0 deletions
diff --git a/gcc/tree-loop-distribution.c b/gcc/tree-loop-distribution.c new file mode 100644 index 00000000000..2d4a5d69373 --- /dev/null +++ b/gcc/tree-loop-distribution.c @@ -0,0 +1,1173 @@ +/* Loop distribution. + Copyright (C) 2006, 2007 Free Software Foundation, Inc. + Contributed by Georges-Andre Silber <Georges-Andre.Silber@ensmp.fr> + and Sebastian Pop <sebastian.pop@amd.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/>. */ + +/* 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 "tm.h" +#include "ggc.h" +#include "tree.h" +#include "target.h" + +#include "rtl.h" +#include "basic-block.h" +#include "diagnostic.h" +#include "tree-flow.h" +#include "tree-dump.h" +#include "timevar.h" +#include "cfgloop.h" +#include "expr.h" +#include "optabs.h" +#include "tree-chrec.h" +#include "tree-data-ref.h" +#include "tree-scalar-evolution.h" +#include "tree-pass.h" +#include "lambda.h" +#include "langhooks.h" +#include "tree-vectorizer.h" + +/* 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; + +/* Update the PHI nodes of NEW_LOOP. NEW_LOOP is a duplicate of + ORIG_LOOP. */ + +static void +update_phis_for_loop_copy (struct loop *orig_loop, struct loop *new_loop) +{ + tree new_ssa_name; + tree phi_new, phi_orig; + edge orig_loop_latch = loop_latch_edge (orig_loop); + edge orig_entry_e = loop_preheader_edge (orig_loop); + edge new_loop_entry_e = loop_preheader_edge (new_loop); + + /* Scan the phis in the headers of the old and new loops + (they are organized in exactly the same order). */ + + for (phi_new = phi_nodes (new_loop->header), + phi_orig = phi_nodes (orig_loop->header); + phi_new && phi_orig; + phi_new = PHI_CHAIN (phi_new), phi_orig = PHI_CHAIN (phi_orig)) + { + /* Add the first phi argument for the phi in NEW_LOOP (the one + associated with the entry of NEW_LOOP) */ + tree def = PHI_ARG_DEF_FROM_EDGE (phi_orig, orig_entry_e); + add_phi_arg (phi_new, def, new_loop_entry_e); + + /* Add the second phi argument for the phi in NEW_LOOP (the one + associated with the latch of NEW_LOOP) */ + def = PHI_ARG_DEF_FROM_EDGE (phi_orig, orig_loop_latch); + + if (TREE_CODE (def) == SSA_NAME) + { + new_ssa_name = get_current_def (def); + + if (!new_ssa_name) + /* This only happens if there are no definitions inside the + loop. Use the phi_result in this case. */ + new_ssa_name = PHI_RESULT (phi_new); + } + else + /* Could be an integer. */ + new_ssa_name = def; + + add_phi_arg (phi_new, new_ssa_name, loop_latch_edge (new_loop)); + } +} + +/* 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); + + if (!single_exit (loop)) + return NULL; + + initialize_original_copy_tables (); + res = slpeel_tree_duplicate_loop_to_edge_cfg (loop, preheader); + free_original_copy_tables (); + + if (!res) + return NULL; + + update_phis_for_loop_copy (loop, res); + rename_variables_in_loop (res); + + 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. Returns true when + the code gen succeeded. */ + +static bool +generate_loops_for_partition (struct loop *loop, bitmap partition, bool copy_p) +{ + unsigned i, x; + block_stmt_iterator bsi; + basic_block *bbs; + + if (copy_p) + { + loop = copy_loop_before (loop); + create_preheader (loop, CP_SIMPLE_PREHEADERS); + create_bb_after_loop (loop); + } + + if (loop == NULL) + return false; + + /* 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); + + for (x = 0, i = 0; i < loop->num_nodes; i++) + { + basic_block bb = bbs[i]; + tree phi, prev = NULL_TREE, next; + + for (phi = phi_nodes (bb); phi;) + if (!bitmap_bit_p (partition, x++)) + { + next = PHI_CHAIN (phi); + remove_phi_node (phi, prev, true); + phi = next; + } + else + { + prev = phi; + phi = PHI_CHAIN (phi); + } + + for (bsi = bsi_start (bb); !bsi_end_p (bsi);) + if (TREE_CODE (bsi_stmt (bsi)) != LABEL_EXPR + && !bitmap_bit_p (partition, x++)) + bsi_remove (&bsi, false); + else + bsi_next (&bsi); + + mark_virtual_ops_in_bb (bb); + } + + free (bbs); + return true; +} + +/* Generate a call to memset. Return true when the operation succeeded. */ + +static bool +generate_memset_zero (tree stmt, tree op0, tree nb_iter, + block_stmt_iterator bsi) +{ + tree s, t, stmts, nb_bytes, addr_base; + bool res = false; + tree stmt_list = NULL_TREE; + tree args [3]; + tree fn_call, mem, fndecl, fntype, fn; + tree_stmt_iterator i; + ssa_op_iter iter; + struct data_reference *dr = XCNEW (struct data_reference); + + nb_bytes = fold_build2 (MULT_EXPR, TREE_TYPE (nb_iter), + nb_iter, TYPE_SIZE_UNIT (TREE_TYPE (op0))); + nb_bytes = force_gimple_operand (nb_bytes, &stmts, true, NULL); + append_to_statement_list_force (stmts, &stmt_list); + + DR_STMT (dr) = stmt; + DR_REF (dr) = op0; + dr_analyze_innermost (dr); + + /* Test for a positive stride, iterating over every element. */ + if (integer_zerop (fold_build2 (MINUS_EXPR, integer_type_node, DR_STEP (dr), + TYPE_SIZE_UNIT (TREE_TYPE (op0))))) + addr_base = fold_build2 (PLUS_EXPR, TREE_TYPE (DR_BASE_ADDRESS (dr)), + DR_BASE_ADDRESS (dr), + size_binop (PLUS_EXPR, + DR_OFFSET (dr), DR_INIT (dr))); + + /* Test for a negative stride, iterating over every element. */ + else if (integer_zerop (fold_build2 (PLUS_EXPR, integer_type_node, + TYPE_SIZE_UNIT (TREE_TYPE (op0)), + DR_STEP (dr)))) + { + addr_base = size_binop (PLUS_EXPR, DR_OFFSET (dr), DR_INIT (dr)); + addr_base = fold_build2 (MINUS_EXPR, sizetype, addr_base, nb_bytes); + addr_base = force_gimple_operand (addr_base, &stmts, true, NULL); + append_to_statement_list_force (stmts, &stmt_list); + + addr_base = fold_build2 (POINTER_PLUS_EXPR, + TREE_TYPE (DR_BASE_ADDRESS (dr)), + DR_BASE_ADDRESS (dr), addr_base); + } + else + goto end; + + mem = force_gimple_operand (addr_base, &stmts, true, NULL); + append_to_statement_list_force (stmts, &stmt_list); + + + fndecl = implicit_built_in_decls [BUILT_IN_MEMSET]; + fntype = TREE_TYPE (fndecl); + fn = build1 (ADDR_EXPR, build_pointer_type (fntype), fndecl); + + args[0] = mem; + args[1] = integer_zero_node; + args[2] = nb_bytes; + + fn_call = build_call_array (fntype, fn, 3, args); + append_to_statement_list_force (fn_call, &stmt_list); + + for (i = tsi_start (stmt_list); !tsi_end_p (i); tsi_next (&i)) + { + s = tsi_stmt (i); + update_stmt_if_modified (s); + + FOR_EACH_SSA_TREE_OPERAND (t, s, iter, SSA_OP_VIRTUAL_DEFS) + { + if (TREE_CODE (t) == SSA_NAME) + t = SSA_NAME_VAR (t); + mark_sym_for_renaming (t); + } + } + + /* Mark also the uses of the VDEFS of STMT to be renamed. */ + FOR_EACH_SSA_TREE_OPERAND (t, stmt, iter, SSA_OP_VIRTUAL_DEFS) + { + if (TREE_CODE (t) == SSA_NAME) + { + imm_use_iterator imm_iter; + + FOR_EACH_IMM_USE_STMT (s, imm_iter, t) + update_stmt (s); + + t = SSA_NAME_VAR (t); + } + mark_sym_for_renaming (t); + } + + bsi_insert_after (&bsi, stmt_list, BSI_CONTINUE_LINKING); + res = true; + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "generated memset zero\n"); + + end: + free_data_ref (dr); + return res; +} + +/* Tries to generate a builtin function for the instructions of LOOP + pointed to by the bits set in PARTITION. Returns true when the + operation succeeded. */ + +static bool +generate_builtin (struct loop *loop, bitmap partition, bool copy_p) +{ + bool res = false; + unsigned i, x = 0; + basic_block *bbs; + tree write = NULL_TREE; + tree op0, op1; + block_stmt_iterator bsi; + tree nb_iter = number_of_exit_cond_executions (loop); + + if (!nb_iter || nb_iter == chrec_dont_know) + return false; + + bbs = get_loop_body_in_dom_order (loop); + + for (i = 0; i < loop->num_nodes; i++) + { + basic_block bb = bbs[i]; + tree phi; + + for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) + x++; + + for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) + { + tree stmt = bsi_stmt (bsi); + + if (bitmap_bit_p (partition, x++) + && TREE_CODE (stmt) == GIMPLE_MODIFY_STMT + && !is_gimple_reg (GIMPLE_STMT_OPERAND (stmt, 0))) + { + /* Don't generate the builtins when there are more than + one memory write. */ + if (write != NULL) + goto end; + + write = stmt; + } + } + } + + if (!write) + goto end; + + op0 = GIMPLE_STMT_OPERAND (write, 0); + op1 = GIMPLE_STMT_OPERAND (write, 1); + + if (!(TREE_CODE (op0) == ARRAY_REF + || TREE_CODE (op0) == INDIRECT_REF)) + goto end; + + /* The new statements will be placed before LOOP. */ + bsi = bsi_last (loop_preheader_edge (loop)->src); + + if (integer_zerop (op1) || real_zerop (op1)) + res = generate_memset_zero (write, op0, nb_iter, bsi); + + /* If this is the last partition for which we generate code, we have + to destroy the loop. */ + if (res && !copy_p) + { + unsigned nbbs = loop->num_nodes; + basic_block src = loop_preheader_edge (loop)->src; + basic_block dest = single_exit (loop)->dest; + make_edge (src, dest, EDGE_FALLTHRU); + set_immediate_dominator (CDI_DOMINATORS, dest, src); + cancel_loop_tree (loop); + + for (i = 0; i < nbbs; i++) + delete_basic_block (bbs[i]); + } + + end: + free (bbs); + return res; +} + +/* Generates code for PARTITION. For simple loops, this function can + generate a built-in. */ + +static bool +generate_code_for_partition (struct loop *loop, bitmap partition, bool copy_p) +{ + if (generate_builtin (loop, partition, copy_p)) + return true; + + return generate_loops_for_partition (loop, partition, copy_p); +} + + +/* 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 among the successors + of vertex V, otherwise returns the edge with the anti-dep. */ + +static struct graph_edge * +has_anti_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) + 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 (int, heap) *nodes = VEC_alloc (int, heap, 3); + bool has_upstream_mem_write_p = false; + + graphds_dfs (rdg, &v, 1, &nodes, false, NULL); + + for (i = 0; VEC_iterate (int, nodes, i, x); i++) + { + if (bitmap_bit_p (seen, x)) + continue; + + bitmap_set_bit (seen, x); + + 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. */ + || has_anti_dependence (&(rdg->vertices[x]))) + { + has_upstream_mem_write_p = true; + bitmap_set_bit (upstream_mem_writes, x); + } + } + + VEC_free (int, heap, nodes); + } +} + +/* 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, bitmap, bitmap, + bitmap, bool *); + +/* Flag all the uses of U. */ + +static void +rdg_flag_all_uses (struct graph *rdg, int u, bitmap partition, bitmap loops, + bitmap processed, bool *part_has_writes) +{ + struct graph_edge *e; + + for (e = rdg->vertices[u].succ; e; e = e->succ_next) + if (!bitmap_bit_p (processed, e->dest)) + { + rdg_flag_vertex_and_dependent (rdg, e->dest, partition, loops, + processed, part_has_writes); + rdg_flag_all_uses (rdg, e->dest, partition, loops, processed, + part_has_writes); + } +} + +/* Flag the uses of U stopping following the information from + upstream_mem_writes. */ + +static void +rdg_flag_uses (struct graph *rdg, int u, bitmap partition, bitmap loops, + bitmap processed, bool *part_has_writes) +{ + ssa_op_iter iter; + use_operand_p use_p; + struct vertex *x = &(rdg->vertices[u]); + tree stmt = RDGV_STMT (x); + struct graph_edge *anti_dep = has_anti_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, part_has_writes); + } + + if (TREE_CODE (stmt) != PHI_NODE) + { + FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_VIRTUAL_USES) + { + tree use = USE_FROM_PTR (use_p); + + if (TREE_CODE (use) == SSA_NAME) + { + tree 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, part_has_writes); + } + } + } + + if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT + && has_upstream_mem_writes (u)) + { + tree op0 = GIMPLE_STMT_OPERAND (stmt, 0); + + /* 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, part_has_writes); + } + } + } +} + +/* 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, bitmap partition, bitmap loops, + bool *part_has_writes) +{ + struct loop *loop; + + if (bitmap_bit_p (partition, v)) + return; + + loop = loop_containing_stmt (RDG_STMT (rdg, v)); + bitmap_set_bit (loops, loop->num); + bitmap_set_bit (partition, v); + + if (rdg_cannot_recompute_vertex_p (rdg, v)) + { + *part_has_writes = true; + bitmap_clear_bit (remaining_stmts, v); + } +} + +/* Flag in the bitmap PARTITION the vertex V and all its predecessors. + Alse flag their loop number in LOOPS. */ + +static void +rdg_flag_vertex_and_dependent (struct graph *rdg, int v, bitmap partition, + bitmap loops, bitmap processed, + bool *part_has_writes) +{ + unsigned i; + VEC (int, heap) *nodes = VEC_alloc (int, heap, 3); + int x; + + bitmap_set_bit (processed, v); + rdg_flag_uses (rdg, v, partition, loops, processed, part_has_writes); + graphds_dfs (rdg, &v, 1, &nodes, false, remaining_stmts); + rdg_flag_vertex (rdg, v, partition, loops, part_has_writes); + + for (i = 0; VEC_iterate (int, nodes, i, x); i++) + if (!already_processed_vertex_p (processed, x)) + rdg_flag_vertex_and_dependent (rdg, x, partition, loops, processed, + part_has_writes); + + VEC_free (int, heap, nodes); +} + +/* Initialize CONDS with all the condition statements from the basic + blocks of LOOP. */ + +static void +collect_condition_stmts (struct loop *loop, VEC (tree, heap) **conds) +{ + unsigned i; + edge e; + VEC (edge, heap) *exits = get_loop_exit_edges (loop); + + for (i = 0; VEC_iterate (edge, exits, i, e); i++) + { + tree cond = last_stmt (e->src); + + if (cond) + VEC_safe_push (tree, heap, *conds, cond); + } + + VEC_free (edge, heap, exits); +} + +/* 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, bitmap partition, + bitmap processed, bool *part_has_writes) +{ + unsigned i; + bitmap_iterator bi; + VEC (tree, heap) *conds = VEC_alloc (tree, heap, 3); + + EXECUTE_IF_SET_IN_BITMAP (loops, 0, i, bi) + collect_condition_stmts (get_loop (i), &conds); + + while (!VEC_empty (tree, conds)) + { + tree cond = VEC_pop (tree, conds); + 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, + part_has_writes); + + EXECUTE_IF_SET_IN_BITMAP (new_loops, 0, i, bi) + if (!bitmap_bit_p (loops, i)) + { + bitmap_set_bit (loops, i); + collect_condition_stmts (get_loop (i), &conds); + } + + BITMAP_FREE (new_loops); + } +} + +/* Strongly connected components of the reduced data dependence graph. */ + +typedef struct rdg_component +{ + int num; + VEC (int, heap) *vertices; +} *rdgc; + +DEF_VEC_P (rdgc); +DEF_VEC_ALLOC_P (rdgc, heap); + +/* Flag all the nodes of RDG containing memory accesses that could + potentially belong to arrays already accessed in the current + PARTITION. */ + +static void +rdg_flag_similar_memory_accesses (struct graph *rdg, bitmap partition, + bitmap loops, bitmap processed, + VEC (int, heap) **other_stores) +{ + bool foo; + unsigned i, n; + int j, k, kk; + bitmap_iterator ii; + struct graph_edge *e; + + EXECUTE_IF_SET_IN_BITMAP (partition, 0, i, ii) + if (RDG_MEM_WRITE_STMT (rdg, i) + || RDG_MEM_READS_STMT (rdg, i)) + { + for (j = 0; j < rdg->n_vertices; j++) + if (!bitmap_bit_p (processed, j) + && (RDG_MEM_WRITE_STMT (rdg, j) + || RDG_MEM_READS_STMT (rdg, j)) + && rdg_has_similar_memory_accesses (rdg, i, j)) + { + /* Flag first the node J itself, and all the nodes that + are needed to compute J. */ + rdg_flag_vertex_and_dependent (rdg, j, partition, loops, + processed, &foo); + + /* When J is a read, we want to coalesce in the same + PARTITION all the nodes that are using J: this is + needed for better cache locality. */ + rdg_flag_all_uses (rdg, j, partition, loops, processed, &foo); + + /* Remove from OTHER_STORES the vertex that we flagged. */ + if (RDG_MEM_WRITE_STMT (rdg, j)) + for (k = 0; VEC_iterate (int, *other_stores, k, kk); k++) + if (kk == j) + { + VEC_unordered_remove (int, *other_stores, k); + break; + } + } + + /* If the node I has two uses, then keep these together in the + same PARTITION. */ + for (n = 0, e = rdg->vertices[i].succ; e; e = e->succ_next, n++); + + if (n > 1) + rdg_flag_all_uses (rdg, i, partition, loops, processed, &foo); + } +} + +/* 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 bitmap +build_rdg_partition_for_component (struct graph *rdg, rdgc c, + bool *part_has_writes, + VEC (int, heap) **other_stores) +{ + int i, v; + bitmap partition = BITMAP_ALLOC (NULL); + bitmap loops = BITMAP_ALLOC (NULL); + bitmap processed = BITMAP_ALLOC (NULL); + + for (i = 0; VEC_iterate (int, c->vertices, i, v); i++) + if (!already_processed_vertex_p (processed, v)) + rdg_flag_vertex_and_dependent (rdg, v, partition, loops, processed, + part_has_writes); + + /* Also iterate on the array of stores not in the starting vertices, + and determine those vertices that have some memory affinity with + the current nodes in the component: these are stores to the same + arrays, i.e. we're taking care of cache locality. */ + rdg_flag_similar_memory_accesses (rdg, partition, loops, processed, + other_stores); + + rdg_flag_loop_exits (rdg, loops, partition, processed, part_has_writes); + + BITMAP_FREE (processed); + BITMAP_FREE (loops); + return partition; +} + +/* Free memory for COMPONENTS. */ + +static void +free_rdg_components (VEC (rdgc, heap) *components) +{ + int i; + rdgc x; + + for (i = 0; VEC_iterate (rdgc, components, i, x); i++) + { + VEC_free (int, heap, x->vertices); + free (x); + } +} + +/* 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 (int, heap) *starting_vertices, + VEC (rdgc, heap) **components) +{ + int i, v; + bitmap saved_components = BITMAP_ALLOC (NULL); + int n_components = graphds_scc (rdg, NULL); + VEC (int, heap) **all_components = XNEWVEC (VEC (int, heap) *, n_components); + + for (i = 0; i < n_components; i++) + all_components[i] = VEC_alloc (int, heap, 3); + + for (i = 0; i < rdg->n_vertices; i++) + VEC_safe_push (int, heap, all_components[rdg->vertices[i].component], i); + + for (i = 0; VEC_iterate (int, starting_vertices, i, v); i++) + { + int c = rdg->vertices[v].component; + + if (!bitmap_bit_p (saved_components, c)) + { + rdgc x = XCNEW (struct rdg_component); + x->num = c; + x->vertices = all_components[c]; + + VEC_safe_push (rdgc, heap, *components, x); + bitmap_set_bit (saved_components, c); + } + } + + for (i = 0; i < n_components; i++) + if (!bitmap_bit_p (saved_components, i)) + VEC_free (int, heap, all_components[i]); + + free (all_components); + BITMAP_FREE (saved_components); +} + +DEF_VEC_P (bitmap); +DEF_VEC_ALLOC_P (bitmap, heap); + +/* 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 (rdgc, heap) *components, + VEC (int, heap) **other_stores, + VEC (bitmap, heap) **partitions, bitmap processed) +{ + int i; + rdgc x; + bitmap partition = BITMAP_ALLOC (NULL); + + for (i = 0; VEC_iterate (rdgc, components, i, x); i++) + { + bitmap np; + bool part_has_writes = false; + int v = VEC_index (int, x->vertices, 0); + + if (bitmap_bit_p (processed, v)) + continue; + + np = build_rdg_partition_for_component (rdg, x, &part_has_writes, + other_stores); + bitmap_ior_into (partition, np); + bitmap_ior_into (processed, np); + BITMAP_FREE (np); + + if (part_has_writes) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "ldist useful partition:\n"); + dump_bitmap (dump_file, partition); + } + + VEC_safe_push (bitmap, heap, *partitions, partition); + partition = BITMAP_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)) + VEC_safe_push (int, heap, *other_stores, i); + + /* If there are still statements left in the OTHER_STORES array, + create other components and partitions with these stores and + their dependences. */ + if (VEC_length (int, *other_stores) > 0) + { + VEC (rdgc, heap) *comps = VEC_alloc (rdgc, heap, 3); + VEC (int, heap) *foo = VEC_alloc (int, heap, 3); + + rdg_build_components (rdg, *other_stores, &comps); + rdg_build_partitions (rdg, comps, &foo, partitions, processed); + + VEC_free (int, heap, foo); + free_rdg_components (comps); + } + + /* If there is something left in the last partition, save it. */ + if (bitmap_count_bits (partition) > 0) + VEC_safe_push (bitmap, heap, *partitions, partition); + else + BITMAP_FREE (partition); +} + +/* Dump to FILE the PARTITIONS. */ + +static void +dump_rdg_partitions (FILE *file, VEC (bitmap, heap) *partitions) +{ + int i; + bitmap partition; + + for (i = 0; VEC_iterate (bitmap, partitions, i, partition); i++) + debug_bitmap_file (file, partition); +} + +/* Debug PARTITIONS. */ +extern void debug_rdg_partitions (VEC (bitmap, heap) *); + +void +debug_rdg_partitions (VEC (bitmap, heap) *partitions) +{ + dump_rdg_partitions (stderr, partitions); +} + +/* Generate code from STARTING_VERTICES in RDG. Returns the number of + distributed loops. */ + +static int +ldist_gen (struct loop *loop, struct graph *rdg, + VEC (int, heap) *starting_vertices) +{ + int i, nbp; + VEC (rdgc, heap) *components = VEC_alloc (rdgc, heap, 3); + VEC (bitmap, heap) *partitions = VEC_alloc (bitmap, heap, 3); + VEC (int, heap) *other_stores = VEC_alloc (int, heap, 3); + bitmap partition, processed = BITMAP_ALLOC (NULL); + + 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 (j = 0; VEC_iterate (int, starting_vertices, j, v); j++) + if (i == v) + { + found = true; + break; + } + + if (!found) + VEC_safe_push (int, heap, other_stores, 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); + nbp = VEC_length (bitmap, partitions); + + if (nbp <= 1) + goto ldist_done; + + if (dump_file && (dump_flags & TDF_DETAILS)) + dump_rdg_partitions (dump_file, partitions); + + for (i = 0; VEC_iterate (bitmap, partitions, i, partition); i++) + if (!generate_code_for_partition (loop, partition, i < nbp - 1)) + goto ldist_done; + + rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa); + update_ssa (TODO_update_ssa_only_virtuals | TODO_update_ssa); + + ldist_done: + + BITMAP_FREE (remaining_stmts); + BITMAP_FREE (upstream_mem_writes); + + for (i = 0; VEC_iterate (bitmap, partitions, i, partition); i++) + BITMAP_FREE (partition); + + VEC_free (int, heap, other_stores); + VEC_free (bitmap, heap, partitions); + 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 (tree, heap) *stmts) +{ + bool res = false; + struct graph *rdg; + tree s; + unsigned i; + VEC (int, heap) *vertices; + + if (loop->num_nodes > 2) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, + "FIXME: Loop %d not distributed: it has more than two basic blocks.\n", + loop->num); + + return res; + } + + rdg = build_rdg (loop); + + 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); + + return res; + } + + vertices = VEC_alloc (int, heap, 3); + + if (dump_file && (dump_flags & TDF_DETAILS)) + dump_rdg (dump_file, rdg); + + for (i = 0; VEC_iterate (tree, stmts, i, s); i++) + { + int v = rdg_vertex_for_stmt (rdg, s); + + if (v >= 0) + { + VEC_safe_push (int, heap, vertices, 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); + VEC_free (int, heap, vertices); + free_rdg (rdg); + + return res; +} + +/* Distribute all loops in the current function. */ + +static unsigned int +tree_loop_distribution (void) +{ + struct loop *loop; + loop_iterator li; + int nb_generated_loops = 0; + + FOR_EACH_LOOP (li, loop, 0) + { + VEC (tree, heap) *work_list = VEC_alloc (tree, heap, 3); + + /* With the following working list, we're asking distribute_loop + to separate the stores of the loop: when dependences allow, + it will end on having one store per loop. */ + stores_from_loop (loop, &work_list); + + /* A simple heuristic for cache locality is to not split stores + to the same array. Without this call, an unrolled loop would + be split into as many loops as unroll factor, each loop + storing in the same array. */ + remove_similar_memory_refs (&work_list); + + nb_generated_loops = distribute_loop (loop, work_list); + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + if (nb_generated_loops > 1) + fprintf (dump_file, "Loop %d distributed: split to %d loops.\n", + loop->num, nb_generated_loops); + else + fprintf (dump_file, "Loop %d is the same.\n", loop->num); + } + + verify_loop_structure (); + + VEC_free (tree, heap, work_list); + } + + return 0; +} + +static bool +gate_tree_loop_distribution (void) +{ + return flag_tree_loop_distribution != 0; +} + +struct tree_opt_pass pass_loop_distribution = +{ + "ldist", /* name */ + 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_dump_func | TODO_verify_loops, /* todo_flags_finish */ + 0 /* letter */ +}; |