/* Data flow functions for trees. Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc. Contributed by Diego Novillo 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 2, 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 COPYING. If not, write to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #include "config.h" #include "system.h" #include "coretypes.h" #include "tm.h" #include "hashtab.h" #include "pointer-set.h" #include "tree.h" #include "rtl.h" #include "tm_p.h" #include "hard-reg-set.h" #include "basic-block.h" #include "output.h" #include "errors.h" #include "timevar.h" #include "expr.h" #include "ggc.h" #include "langhooks.h" #include "flags.h" #include "function.h" #include "diagnostic.h" #include "tree-dump.h" #include "tree-gimple.h" #include "tree-flow.h" #include "tree-inline.h" #include "tree-pass.h" #include "convert.h" #include "params.h" #include "cgraph.h" /* Build and maintain data flow information for trees. */ /* Counters used to display DFA and SSA statistics. */ struct dfa_stats_d { long num_stmt_anns; long num_var_anns; long num_defs; long num_uses; long num_phis; long num_phi_args; int max_num_phi_args; long num_v_may_defs; long num_vuses; long num_v_must_defs; }; /* State information for find_vars_r. */ struct walk_state { /* Hash table used to avoid adding the same variable more than once. */ htab_t vars_found; }; /* Local functions. */ static void collect_dfa_stats (struct dfa_stats_d *); static tree collect_dfa_stats_r (tree *, int *, void *); static tree find_vars_r (tree *, int *, void *); static void add_referenced_var (tree, struct walk_state *); /* Global declarations. */ /* Array of all variables referenced in the function. */ varray_type referenced_vars; /*--------------------------------------------------------------------------- Dataflow analysis (DFA) routines ---------------------------------------------------------------------------*/ /* Find all the variables referenced in the function. This function builds the global arrays REFERENCED_VARS and CALL_CLOBBERED_VARS. Note that this function does not look for statement operands, it simply determines what variables are referenced in the program and detects various attributes for each variable used by alias analysis and the optimizer. */ static void find_referenced_vars (void) { htab_t vars_found; basic_block bb; block_stmt_iterator si; struct walk_state walk_state; vars_found = htab_create (50, htab_hash_pointer, htab_eq_pointer, NULL); memset (&walk_state, 0, sizeof (walk_state)); walk_state.vars_found = vars_found; FOR_EACH_BB (bb) for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si)) { tree *stmt_p = bsi_stmt_ptr (si); walk_tree (stmt_p, find_vars_r, &walk_state, NULL); } htab_delete (vars_found); } struct tree_opt_pass pass_referenced_vars = { NULL, /* name */ NULL, /* gate */ find_referenced_vars, /* execute */ NULL, /* sub */ NULL, /* next */ 0, /* static_pass_number */ TV_FIND_REFERENCED_VARS, /* tv_id */ PROP_gimple_leh | PROP_cfg, /* properties_required */ PROP_referenced_vars, /* properties_provided */ 0, /* properties_destroyed */ 0, /* todo_flags_start */ 0, /* todo_flags_finish */ 0 /* letter */ }; /*--------------------------------------------------------------------------- Manage annotations ---------------------------------------------------------------------------*/ /* Create a new annotation for a _DECL node T. */ var_ann_t create_var_ann (tree t) { var_ann_t ann; gcc_assert (t); gcc_assert (DECL_P (t)); gcc_assert (!t->common.ann || t->common.ann->common.type == VAR_ANN); ann = ggc_alloc (sizeof (*ann)); memset ((void *) ann, 0, sizeof (*ann)); ann->common.type = VAR_ANN; t->common.ann = (tree_ann_t) ann; return ann; } /* Create a new annotation for a statement node T. */ stmt_ann_t create_stmt_ann (tree t) { stmt_ann_t ann; gcc_assert (is_gimple_stmt (t)); gcc_assert (!t->common.ann || t->common.ann->common.type == STMT_ANN); ann = ggc_alloc (sizeof (*ann)); memset ((void *) ann, 0, sizeof (*ann)); ann->common.type = STMT_ANN; /* Since we just created the annotation, mark the statement modified. */ ann->modified = true; t->common.ann = (tree_ann_t) ann; return ann; } /* Create a new annotation for a tree T. */ tree_ann_t create_tree_ann (tree t) { tree_ann_t ann; gcc_assert (t); gcc_assert (!t->common.ann || t->common.ann->common.type == TREE_ANN_COMMON); ann = ggc_alloc (sizeof (*ann)); memset ((void *) ann, 0, sizeof (*ann)); ann->common.type = TREE_ANN_COMMON; t->common.ann = ann; return ann; } /* Build a temporary. Make sure and register it to be renamed. */ tree make_rename_temp (tree type, const char *prefix) { tree t = create_tmp_var (type, prefix); if (referenced_vars) { add_referenced_tmp_var (t); bitmap_set_bit (vars_to_rename, var_ann (t)->uid); } return t; } /*--------------------------------------------------------------------------- Debugging functions ---------------------------------------------------------------------------*/ /* Dump the list of all the referenced variables in the current function to FILE. */ void dump_referenced_vars (FILE *file) { size_t i; fprintf (file, "\nReferenced variables in %s: %u\n\n", get_name (current_function_decl), (unsigned) num_referenced_vars); for (i = 0; i < num_referenced_vars; i++) { tree var = referenced_var (i); fprintf (file, "Variable: "); dump_variable (file, var); fprintf (file, "\n"); } } /* Dump the list of all the referenced variables to stderr. */ void debug_referenced_vars (void) { dump_referenced_vars (stderr); } /* Dump variable VAR and its may-aliases to FILE. */ void dump_variable (FILE *file, tree var) { var_ann_t ann; if (TREE_CODE (var) == SSA_NAME) { if (POINTER_TYPE_P (TREE_TYPE (var))) dump_points_to_info_for (file, var); var = SSA_NAME_VAR (var); } if (var == NULL_TREE) { fprintf (file, ""); return; } print_generic_expr (file, var, dump_flags); ann = var_ann (var); fprintf (file, ", UID %u", (unsigned) ann->uid); fprintf (file, ", "); print_generic_expr (file, TREE_TYPE (var), dump_flags); if (ann->type_mem_tag) { fprintf (file, ", type memory tag: "); print_generic_expr (file, ann->type_mem_tag, dump_flags); } if (ann->is_alias_tag) fprintf (file, ", is an alias tag"); if (TREE_ADDRESSABLE (var)) fprintf (file, ", is addressable"); if (is_global_var (var)) fprintf (file, ", is global"); if (TREE_THIS_VOLATILE (var)) fprintf (file, ", is volatile"); if (is_call_clobbered (var)) fprintf (file, ", call clobbered"); if (ann->default_def) { fprintf (file, ", default def: "); print_generic_expr (file, ann->default_def, dump_flags); } if (ann->may_aliases) { fprintf (file, ", may aliases: "); dump_may_aliases_for (file, var); } fprintf (file, "\n"); } /* Dump variable VAR and its may-aliases to stderr. */ void debug_variable (tree var) { dump_variable (stderr, var); } /* Dump various DFA statistics to FILE. */ void dump_dfa_stats (FILE *file) { struct dfa_stats_d dfa_stats; unsigned long size, total = 0; const char * const fmt_str = "%-30s%-13s%12s\n"; const char * const fmt_str_1 = "%-30s%13lu%11lu%c\n"; const char * const fmt_str_3 = "%-43s%11lu%c\n"; const char *funcname = lang_hooks.decl_printable_name (current_function_decl, 2); collect_dfa_stats (&dfa_stats); fprintf (file, "\nDFA Statistics for %s\n\n", funcname); fprintf (file, "---------------------------------------------------------\n"); fprintf (file, fmt_str, "", " Number of ", "Memory"); fprintf (file, fmt_str, "", " instances ", "used "); fprintf (file, "---------------------------------------------------------\n"); size = num_referenced_vars * sizeof (tree); total += size; fprintf (file, fmt_str_1, "Referenced variables", (unsigned long)num_referenced_vars, SCALE (size), LABEL (size)); size = dfa_stats.num_stmt_anns * sizeof (struct stmt_ann_d); total += size; fprintf (file, fmt_str_1, "Statements annotated", dfa_stats.num_stmt_anns, SCALE (size), LABEL (size)); size = dfa_stats.num_var_anns * sizeof (struct var_ann_d); total += size; fprintf (file, fmt_str_1, "Variables annotated", dfa_stats.num_var_anns, SCALE (size), LABEL (size)); size = dfa_stats.num_uses * sizeof (tree *); total += size; fprintf (file, fmt_str_1, "USE operands", dfa_stats.num_uses, SCALE (size), LABEL (size)); size = dfa_stats.num_defs * sizeof (tree *); total += size; fprintf (file, fmt_str_1, "DEF operands", dfa_stats.num_defs, SCALE (size), LABEL (size)); size = dfa_stats.num_vuses * sizeof (tree *); total += size; fprintf (file, fmt_str_1, "VUSE operands", dfa_stats.num_vuses, SCALE (size), LABEL (size)); size = dfa_stats.num_v_may_defs * sizeof (tree *); total += size; fprintf (file, fmt_str_1, "V_MAY_DEF operands", dfa_stats.num_v_may_defs, SCALE (size), LABEL (size)); size = dfa_stats.num_v_must_defs * sizeof (tree *); total += size; fprintf (file, fmt_str_1, "V_MUST_DEF operands", dfa_stats.num_v_must_defs, SCALE (size), LABEL (size)); size = dfa_stats.num_phis * sizeof (struct tree_phi_node); total += size; fprintf (file, fmt_str_1, "PHI nodes", dfa_stats.num_phis, SCALE (size), LABEL (size)); size = dfa_stats.num_phi_args * sizeof (struct phi_arg_d); total += size; fprintf (file, fmt_str_1, "PHI arguments", dfa_stats.num_phi_args, SCALE (size), LABEL (size)); fprintf (file, "---------------------------------------------------------\n"); fprintf (file, fmt_str_3, "Total memory used by DFA/SSA data", SCALE (total), LABEL (total)); fprintf (file, "---------------------------------------------------------\n"); fprintf (file, "\n"); if (dfa_stats.num_phis) fprintf (file, "Average number of arguments per PHI node: %.1f (max: %d)\n", (float) dfa_stats.num_phi_args / (float) dfa_stats.num_phis, dfa_stats.max_num_phi_args); fprintf (file, "\n"); } /* Dump DFA statistics on stderr. */ void debug_dfa_stats (void) { dump_dfa_stats (stderr); } /* Collect DFA statistics and store them in the structure pointed by DFA_STATS_P. */ static void collect_dfa_stats (struct dfa_stats_d *dfa_stats_p) { struct pointer_set_t *pset; basic_block bb; block_stmt_iterator i; gcc_assert (dfa_stats_p); memset ((void *)dfa_stats_p, 0, sizeof (struct dfa_stats_d)); /* Walk all the trees in the function counting references. Start at basic block 0, but don't stop at block boundaries. */ pset = pointer_set_create (); for (i = bsi_start (BASIC_BLOCK (0)); !bsi_end_p (i); bsi_next (&i)) walk_tree (bsi_stmt_ptr (i), collect_dfa_stats_r, (void *) dfa_stats_p, pset); pointer_set_destroy (pset); FOR_EACH_BB (bb) { tree phi; for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) { dfa_stats_p->num_phis++; dfa_stats_p->num_phi_args += PHI_NUM_ARGS (phi); if (PHI_NUM_ARGS (phi) > dfa_stats_p->max_num_phi_args) dfa_stats_p->max_num_phi_args = PHI_NUM_ARGS (phi); } } } /* Callback for walk_tree to collect DFA statistics for a tree and its children. */ static tree collect_dfa_stats_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED, void *data) { tree t = *tp; struct dfa_stats_d *dfa_stats_p = (struct dfa_stats_d *)data; if (t->common.ann) { switch (ann_type (t->common.ann)) { case STMT_ANN: { stmt_ann_t ann = (stmt_ann_t) t->common.ann; dfa_stats_p->num_stmt_anns++; dfa_stats_p->num_defs += NUM_DEFS (DEF_OPS (ann)); dfa_stats_p->num_uses += NUM_USES (USE_OPS (ann)); dfa_stats_p->num_v_may_defs += NUM_V_MAY_DEFS (V_MAY_DEF_OPS (ann)); dfa_stats_p->num_vuses += NUM_VUSES (VUSE_OPS (ann)); dfa_stats_p->num_v_must_defs += NUM_V_MUST_DEFS (V_MUST_DEF_OPS (ann)); break; } case VAR_ANN: dfa_stats_p->num_var_anns++; break; default: break; } } return NULL; } /*--------------------------------------------------------------------------- Miscellaneous helpers ---------------------------------------------------------------------------*/ /* Callback for walk_tree. Used to collect variables referenced in the function. */ static tree find_vars_r (tree *tp, int *walk_subtrees, void *data) { struct walk_state *walk_state = (struct walk_state *) data; /* If T is a regular variable that the optimizers are interested in, add it to the list of variables. */ if (SSA_VAR_P (*tp)) add_referenced_var (*tp, walk_state); /* Type, _DECL and constant nodes have no interesting children. Ignore them. */ else if (IS_TYPE_OR_DECL_P (*tp) || CONSTANT_CLASS_P (*tp)) *walk_subtrees = 0; return NULL_TREE; } /* Add VAR to the list of dereferenced variables. WALK_STATE contains a hash table used to avoid adding the same variable more than once. Note that this function assumes that VAR is a valid SSA variable. If WALK_STATE is NULL, no duplicate checking is done. */ static void add_referenced_var (tree var, struct walk_state *walk_state) { void **slot; var_ann_t v_ann; v_ann = get_var_ann (var); if (walk_state) slot = htab_find_slot (walk_state->vars_found, (void *) var, INSERT); else slot = NULL; if (slot == NULL || *slot == NULL) { /* This is the first time we find this variable, add it to the REFERENCED_VARS array and annotate it with attributes that are intrinsic to the variable. */ if (slot) *slot = (void *) var; v_ann->uid = num_referenced_vars; VARRAY_PUSH_TREE (referenced_vars, var); /* Global variables are always call-clobbered. */ if (is_global_var (var)) mark_call_clobbered (var); /* Scan DECL_INITIAL for pointer variables as they may contain address arithmetic referencing the address of other variables. */ if (DECL_INITIAL (var) /* Initializers of external variables are not useful to the optimizers. */ && !DECL_EXTERNAL (var) /* It's not necessary to walk the initial value of non-constant public variables because it cannot be propagated by the optimizers. */ && (!TREE_PUBLIC (var) || !TREE_CONSTANT (var))) walk_tree (&DECL_INITIAL (var), find_vars_r, walk_state, 0); } } /* Return the virtual variable associated to the non-scalar variable VAR. */ tree get_virtual_var (tree var) { STRIP_NOPS (var); if (TREE_CODE (var) == SSA_NAME) var = SSA_NAME_VAR (var); while (TREE_CODE (var) == REALPART_EXPR || TREE_CODE (var) == IMAGPART_EXPR || handled_component_p (var)) var = TREE_OPERAND (var, 0); /* Treating GIMPLE registers as virtual variables makes no sense. Also complain if we couldn't extract a _DECL out of the original expression. */ gcc_assert (SSA_VAR_P (var)); gcc_assert (!is_gimple_reg (var)); return var; } /* Add a temporary variable to REFERENCED_VARS. This is similar to add_referenced_var, but is used by passes that need to add new temps to the REFERENCED_VARS array after the program has been scanned for variables. The variable will just receive a new UID and be added to the REFERENCED_VARS array without checking for duplicates. */ void add_referenced_tmp_var (tree var) { add_referenced_var (var, NULL); } /* Add all the non-SSA variables found in STMT's operands to the bitmap VARS_TO_RENAME. */ void mark_new_vars_to_rename (tree stmt, bitmap vars_to_rename) { ssa_op_iter iter; tree val; bitmap vars_in_vops_to_rename; bool found_exposed_symbol = false; int v_may_defs_before, v_may_defs_after; int v_must_defs_before, v_must_defs_after; vars_in_vops_to_rename = BITMAP_ALLOC (NULL); /* Before re-scanning the statement for operands, mark the existing virtual operands to be renamed again. We do this because when new symbols are exposed, the virtual operands that were here before due to aliasing will probably be removed by the call to get_stmt_operand. Therefore, we need to flag them to be renamed beforehand. We flag them in a separate bitmap because we don't really want to rename them if there are not any newly exposed symbols in the statement operands. */ v_may_defs_before = NUM_V_MAY_DEFS (STMT_V_MAY_DEF_OPS (stmt)); v_must_defs_before = NUM_V_MUST_DEFS (STMT_V_MUST_DEF_OPS (stmt)); FOR_EACH_SSA_TREE_OPERAND (val, stmt, iter, SSA_OP_VMAYDEF | SSA_OP_VUSE | SSA_OP_VMUSTDEF) { if (!DECL_P (val)) val = SSA_NAME_VAR (val); bitmap_set_bit (vars_in_vops_to_rename, var_ann (val)->uid); } /* Now force an operand re-scan on the statement and mark any newly exposed variables. */ update_stmt (stmt); v_may_defs_after = NUM_V_MAY_DEFS (STMT_V_MAY_DEF_OPS (stmt)); v_must_defs_after = NUM_V_MUST_DEFS (STMT_V_MUST_DEF_OPS (stmt)); FOR_EACH_SSA_TREE_OPERAND (val, stmt, iter, SSA_OP_ALL_OPERANDS) { if (DECL_P (val)) { found_exposed_symbol = true; bitmap_set_bit (vars_to_rename, var_ann (val)->uid); } } /* If we found any newly exposed symbols, or if there are fewer VDEF operands in the statement, add the variables we had set in VARS_IN_VOPS_TO_RENAME to VARS_TO_RENAME. We need to check for vanishing VDEFs because in those cases, the names that were formerly generated by this statement are not going to be available anymore. */ if (found_exposed_symbol || v_may_defs_before > v_may_defs_after || v_must_defs_before > v_must_defs_after) bitmap_ior_into (vars_to_rename, vars_in_vops_to_rename); BITMAP_FREE (vars_in_vops_to_rename); } /* Find all variables within the gimplified statement that were not previously visible to the function and add them to the referenced variables list. */ static tree find_new_referenced_vars_1 (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED) { tree t = *tp; if (TREE_CODE (t) == VAR_DECL && !var_ann (t)) add_referenced_tmp_var (t); if (IS_TYPE_OR_DECL_P (t)) *walk_subtrees = 0; return NULL; } void find_new_referenced_vars (tree *stmt_p) { walk_tree (stmt_p, find_new_referenced_vars_1, NULL, NULL); } /* Mark all call-clobbered variables for renaming. */ void mark_call_clobbered_vars_to_rename (void) { unsigned i; bitmap_iterator bi; EXECUTE_IF_SET_IN_BITMAP (call_clobbered_vars, 0, i, bi) { tree var = referenced_var (i); bitmap_set_bit (vars_to_rename, var_ann (var)->uid); } } /* If REF is a COMPONENT_REF for a structure that can have sub-variables, and we know where REF is accessing, return the variable in REF that has the sub-variables. If the return value is not NULL, POFFSET will be the offset, in bits, of REF inside the return value, and PSIZE will be the size, in bits, of REF inside the return value. */ tree okay_component_ref_for_subvars (tree ref, HOST_WIDE_INT *poffset, HOST_WIDE_INT *psize) { tree result = NULL; HOST_WIDE_INT bitsize; HOST_WIDE_INT bitpos; tree offset; enum machine_mode mode; int unsignedp; int volatilep; gcc_assert (!SSA_VAR_P (ref)); *poffset = 0; *psize = (unsigned int) -1; if (ref_contains_array_ref (ref)) return result; ref = get_inner_reference (ref, &bitsize, &bitpos, &offset, &mode, &unsignedp, &volatilep, false); if (TREE_CODE (ref) == INDIRECT_REF) return result; else if (offset == NULL && bitsize != -1 && SSA_VAR_P (ref)) { *poffset = bitpos; *psize = bitsize; if (get_subvars_for_var (ref) != NULL) return ref; } else if (SSA_VAR_P (ref)) { if (get_subvars_for_var (ref) != NULL) return ref; } return NULL_TREE; }