URL
https://opencores.org/ocsvn/openrisc/openrisc/trunk
Subversion Repositories openrisc
[/] [openrisc/] [trunk/] [gnu-stable/] [gcc-4.5.1/] [gcc/] [tree-ssa-live.c] - Rev 816
Go to most recent revision | Compare with Previous | Blame | View Log
/* Liveness for SSA trees. Copyright (C) 2003, 2004, 2005, 2007, 2008, 2009 Free Software Foundation, Inc. Contributed by Andrew MacLeod <amacleod@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 "tm.h" #include "tree.h" #include "diagnostic.h" #include "bitmap.h" #include "tree-flow.h" #include "tree-dump.h" #include "tree-ssa-live.h" #include "toplev.h" #include "debug.h" #include "flags.h" #ifdef ENABLE_CHECKING static void verify_live_on_entry (tree_live_info_p); #endif /* VARMAP maintains a mapping from SSA version number to real variables. All SSA_NAMES are divided into partitions. Initially each ssa_name is the only member of it's own partition. Coalescing will attempt to group any ssa_names which occur in a copy or in a PHI node into the same partition. At the end of out-of-ssa, each partition becomes a "real" variable and is rewritten as a compiler variable. The var_map data structure is used to manage these partitions. It allows partitions to be combined, and determines which partition belongs to what ssa_name or variable, and vice versa. */ /* This routine will initialize the basevar fields of MAP. */ static void var_map_base_init (var_map map) { int x, num_part, num; tree var; var_ann_t ann; num = 0; num_part = num_var_partitions (map); /* If a base table already exists, clear it, otherwise create it. */ if (map->partition_to_base_index != NULL) { free (map->partition_to_base_index); VEC_truncate (tree, map->basevars, 0); } else map->basevars = VEC_alloc (tree, heap, MAX (40, (num_part / 10))); map->partition_to_base_index = (int *) xmalloc (sizeof (int) * num_part); /* Build the base variable list, and point partitions at their bases. */ for (x = 0; x < num_part; x++) { var = partition_to_var (map, x); if (TREE_CODE (var) == SSA_NAME) var = SSA_NAME_VAR (var); ann = var_ann (var); /* If base variable hasn't been seen, set it up. */ if (!ann->base_var_processed) { ann->base_var_processed = 1; VAR_ANN_BASE_INDEX (ann) = num++; VEC_safe_push (tree, heap, map->basevars, var); } map->partition_to_base_index[x] = VAR_ANN_BASE_INDEX (ann); } map->num_basevars = num; /* Now clear the processed bit. */ for (x = 0; x < num; x++) { var = VEC_index (tree, map->basevars, x); var_ann (var)->base_var_processed = 0; } #ifdef ENABLE_CHECKING for (x = 0; x < num_part; x++) { tree var2; var = SSA_NAME_VAR (partition_to_var (map, x)); var2 = VEC_index (tree, map->basevars, basevar_index (map, x)); gcc_assert (var == var2); } #endif } /* Remove the base table in MAP. */ static void var_map_base_fini (var_map map) { /* Free the basevar info if it is present. */ if (map->partition_to_base_index != NULL) { VEC_free (tree, heap, map->basevars); free (map->partition_to_base_index); map->partition_to_base_index = NULL; map->num_basevars = 0; } } /* Create a variable partition map of SIZE, initialize and return it. */ var_map init_var_map (int size) { var_map map; map = (var_map) xmalloc (sizeof (struct _var_map)); map->var_partition = partition_new (size); map->partition_to_view = NULL; map->view_to_partition = NULL; map->num_partitions = size; map->partition_size = size; map->num_basevars = 0; map->partition_to_base_index = NULL; map->basevars = NULL; return map; } /* Free memory associated with MAP. */ void delete_var_map (var_map map) { var_map_base_fini (map); partition_delete (map->var_partition); if (map->partition_to_view) free (map->partition_to_view); if (map->view_to_partition) free (map->view_to_partition); free (map); } /* This function will combine the partitions in MAP for VAR1 and VAR2. It Returns the partition which represents the new partition. If the two partitions cannot be combined, NO_PARTITION is returned. */ int var_union (var_map map, tree var1, tree var2) { int p1, p2, p3; gcc_assert (TREE_CODE (var1) == SSA_NAME); gcc_assert (TREE_CODE (var2) == SSA_NAME); /* This is independent of partition_to_view. If partition_to_view is on, then whichever one of these partitions is absorbed will never have a dereference into the partition_to_view array any more. */ p1 = partition_find (map->var_partition, SSA_NAME_VERSION (var1)); p2 = partition_find (map->var_partition, SSA_NAME_VERSION (var2)); gcc_assert (p1 != NO_PARTITION); gcc_assert (p2 != NO_PARTITION); if (p1 == p2) p3 = p1; else p3 = partition_union (map->var_partition, p1, p2); if (map->partition_to_view) p3 = map->partition_to_view[p3]; return p3; } /* Compress the partition numbers in MAP such that they fall in the range 0..(num_partitions-1) instead of wherever they turned out during the partitioning exercise. This removes any references to unused partitions, thereby allowing bitmaps and other vectors to be much denser. This is implemented such that compaction doesn't affect partitioning. Ie., once partitions are created and possibly merged, running one or more different kind of compaction will not affect the partitions themselves. Their index might change, but all the same variables will still be members of the same partition group. This allows work on reduced sets, and no loss of information when a larger set is later desired. In particular, coalescing can work on partitions which have 2 or more definitions, and then 'recompact' later to include all the single definitions for assignment to program variables. */ /* Set MAP back to the initial state of having no partition view. Return a bitmap which has a bit set for each partition number which is in use in the varmap. */ static bitmap partition_view_init (var_map map) { bitmap used; int tmp; unsigned int x; used = BITMAP_ALLOC (NULL); /* Already in a view? Abandon the old one. */ if (map->partition_to_view) { free (map->partition_to_view); map->partition_to_view = NULL; } if (map->view_to_partition) { free (map->view_to_partition); map->view_to_partition = NULL; } /* Find out which partitions are actually referenced. */ for (x = 0; x < map->partition_size; x++) { tmp = partition_find (map->var_partition, x); if (ssa_name (tmp) != NULL_TREE && is_gimple_reg (ssa_name (tmp)) && (!has_zero_uses (ssa_name (tmp)) || !SSA_NAME_IS_DEFAULT_DEF (ssa_name (tmp)))) bitmap_set_bit (used, tmp); } map->num_partitions = map->partition_size; return used; } /* This routine will finalize the view data for MAP based on the partitions set in SELECTED. This is either the same bitmap returned from partition_view_init, or a trimmed down version if some of those partitions were not desired in this view. SELECTED is freed before returning. */ static void partition_view_fini (var_map map, bitmap selected) { bitmap_iterator bi; unsigned count, i, x, limit; gcc_assert (selected); count = bitmap_count_bits (selected); limit = map->partition_size; /* If its a one-to-one ratio, we don't need any view compaction. */ if (count < limit) { map->partition_to_view = (int *)xmalloc (limit * sizeof (int)); memset (map->partition_to_view, 0xff, (limit * sizeof (int))); map->view_to_partition = (int *)xmalloc (count * sizeof (int)); i = 0; /* Give each selected partition an index. */ EXECUTE_IF_SET_IN_BITMAP (selected, 0, x, bi) { map->partition_to_view[x] = i; map->view_to_partition[i] = x; i++; } gcc_assert (i == count); map->num_partitions = i; } BITMAP_FREE (selected); } /* Create a partition view which includes all the used partitions in MAP. If WANT_BASES is true, create the base variable map as well. */ extern void partition_view_normal (var_map map, bool want_bases) { bitmap used; used = partition_view_init (map); partition_view_fini (map, used); if (want_bases) var_map_base_init (map); else var_map_base_fini (map); } /* Create a partition view in MAP which includes just partitions which occur in the bitmap ONLY. If WANT_BASES is true, create the base variable map as well. */ extern void partition_view_bitmap (var_map map, bitmap only, bool want_bases) { bitmap used; bitmap new_partitions = BITMAP_ALLOC (NULL); unsigned x, p; bitmap_iterator bi; used = partition_view_init (map); EXECUTE_IF_SET_IN_BITMAP (only, 0, x, bi) { p = partition_find (map->var_partition, x); gcc_assert (bitmap_bit_p (used, p)); bitmap_set_bit (new_partitions, p); } partition_view_fini (map, new_partitions); BITMAP_FREE (used); if (want_bases) var_map_base_init (map); else var_map_base_fini (map); } static inline void mark_all_vars_used (tree *, void *data); /* Helper function for mark_all_vars_used, called via walk_tree. */ static tree mark_all_vars_used_1 (tree *tp, int *walk_subtrees, void *data) { tree t = *tp; enum tree_code_class c = TREE_CODE_CLASS (TREE_CODE (t)); tree b; if (TREE_CODE (t) == SSA_NAME) t = SSA_NAME_VAR (t); if (IS_EXPR_CODE_CLASS (c) && (b = TREE_BLOCK (t)) != NULL) TREE_USED (b) = true; /* Ignore TREE_ORIGINAL for TARGET_MEM_REFS, as well as other fields that do not contain vars. */ if (TREE_CODE (t) == TARGET_MEM_REF) { mark_all_vars_used (&TMR_SYMBOL (t), data); mark_all_vars_used (&TMR_BASE (t), data); mark_all_vars_used (&TMR_INDEX (t), data); *walk_subtrees = 0; return NULL; } /* Only need to mark VAR_DECLS; parameters and return results are not eliminated as unused. */ if (TREE_CODE (t) == VAR_DECL) { if (data != NULL && bitmap_bit_p ((bitmap) data, DECL_UID (t))) { bitmap_clear_bit ((bitmap) data, DECL_UID (t)); mark_all_vars_used (&DECL_INITIAL (t), data); } set_is_used (t); } if (IS_TYPE_OR_DECL_P (t)) *walk_subtrees = 0; return NULL; } /* Mark the scope block SCOPE and its subblocks unused when they can be possibly eliminated if dead. */ static void mark_scope_block_unused (tree scope) { tree t; TREE_USED (scope) = false; if (!(*debug_hooks->ignore_block) (scope)) TREE_USED (scope) = true; for (t = BLOCK_SUBBLOCKS (scope); t ; t = BLOCK_CHAIN (t)) mark_scope_block_unused (t); } /* Look if the block is dead (by possibly eliminating its dead subblocks) and return true if so. Block is declared dead if: 1) No statements are associated with it. 2) Declares no live variables 3) All subblocks are dead or there is precisely one subblocks and the block has same abstract origin as outer block and declares no variables, so it is pure wrapper. When we are not outputting full debug info, we also eliminate dead variables out of scope blocks to let them to be recycled by GGC and to save copying work done by the inliner. */ static bool remove_unused_scope_block_p (tree scope) { tree *t, *next; bool unused = !TREE_USED (scope); var_ann_t ann; int nsubblocks = 0; for (t = &BLOCK_VARS (scope); *t; t = next) { next = &TREE_CHAIN (*t); /* Debug info of nested function refers to the block of the function. We might stil call it even if all statements of function it was nested into was elliminated. TODO: We can actually look into cgraph to see if function will be output to file. */ if (TREE_CODE (*t) == FUNCTION_DECL) unused = false; /* If a decl has a value expr, we need to instantiate it regardless of debug info generation, to avoid codegen differences in memory overlap tests. update_equiv_regs() may indirectly call validate_equiv_mem() to test whether a SET_DEST overlaps with others, and if the value expr changes by virtual register instantiation, we may get end up with different results. */ else if (TREE_CODE (*t) == VAR_DECL && DECL_HAS_VALUE_EXPR_P (*t)) unused = false; /* Remove everything we don't generate debug info for. */ else if (DECL_IGNORED_P (*t)) { *t = TREE_CHAIN (*t); next = t; } /* When we are outputting debug info, we usually want to output info about optimized-out variables in the scope blocks. Exception are the scope blocks not containing any instructions at all so user can't get into the scopes at first place. */ else if ((ann = var_ann (*t)) != NULL && ann->used) unused = false; /* When we are not doing full debug info, we however can keep around only the used variables for cfgexpand's memory packing saving quite a lot of memory. For sake of -g3, we keep around those vars but we don't count this as use of block, so innermost block with no used vars and no instructions can be considered dead. We only want to keep around blocks user can breakpoint into and ask about value of optimized out variables. Similarly we need to keep around types at least until all variables of all nested blocks are gone. We track no information on whether given type is used or not. */ else if (debug_info_level == DINFO_LEVEL_NORMAL || debug_info_level == DINFO_LEVEL_VERBOSE) ; else { *t = TREE_CHAIN (*t); next = t; } } for (t = &BLOCK_SUBBLOCKS (scope); *t ;) if (remove_unused_scope_block_p (*t)) { if (BLOCK_SUBBLOCKS (*t)) { tree next = BLOCK_CHAIN (*t); tree supercontext = BLOCK_SUPERCONTEXT (*t); *t = BLOCK_SUBBLOCKS (*t); while (BLOCK_CHAIN (*t)) { BLOCK_SUPERCONTEXT (*t) = supercontext; t = &BLOCK_CHAIN (*t); } BLOCK_CHAIN (*t) = next; BLOCK_SUPERCONTEXT (*t) = supercontext; t = &BLOCK_CHAIN (*t); nsubblocks ++; } else *t = BLOCK_CHAIN (*t); } else { t = &BLOCK_CHAIN (*t); nsubblocks ++; } if (!unused) ; /* Outer scope is always used. */ else if (!BLOCK_SUPERCONTEXT (scope) || TREE_CODE (BLOCK_SUPERCONTEXT (scope)) == FUNCTION_DECL) unused = false; /* Innermost blocks with no live variables nor statements can be always eliminated. */ else if (!nsubblocks) ; /* For terse debug info we can eliminate info on unused variables. */ else if (debug_info_level == DINFO_LEVEL_NONE || debug_info_level == DINFO_LEVEL_TERSE) { /* Even for -g0/-g1 don't prune outer scopes from artificial functions, otherwise diagnostics using tree_nonartificial_location will not be emitted properly. */ if (inlined_function_outer_scope_p (scope)) { tree ao = scope; while (ao && TREE_CODE (ao) == BLOCK && BLOCK_ABSTRACT_ORIGIN (ao) != ao) ao = BLOCK_ABSTRACT_ORIGIN (ao); if (ao && TREE_CODE (ao) == FUNCTION_DECL && DECL_DECLARED_INLINE_P (ao) && lookup_attribute ("artificial", DECL_ATTRIBUTES (ao))) unused = false; } } else if (BLOCK_VARS (scope) || BLOCK_NUM_NONLOCALIZED_VARS (scope)) unused = false; /* See if this block is important for representation of inlined function. Inlined functions are always represented by block with block_ultimate_origin being set to FUNCTION_DECL and DECL_SOURCE_LOCATION set... */ else if (inlined_function_outer_scope_p (scope)) unused = false; else /* Verfify that only blocks with source location set are entry points to the inlined functions. */ gcc_assert (BLOCK_SOURCE_LOCATION (scope) == UNKNOWN_LOCATION); TREE_USED (scope) = !unused; return unused; } /* Mark all VAR_DECLS under *EXPR_P as used, so that they won't be eliminated during the tree->rtl conversion process. */ static inline void mark_all_vars_used (tree *expr_p, void *data) { walk_tree (expr_p, mark_all_vars_used_1, data, NULL); } /* Dump scope blocks starting at SCOPE to FILE. INDENT is the indentation level and FLAGS is as in print_generic_expr. */ static void dump_scope_block (FILE *file, int indent, tree scope, int flags) { tree var, t; unsigned int i; fprintf (file, "\n%*s{ Scope block #%i%s%s",indent, "" , BLOCK_NUMBER (scope), TREE_USED (scope) ? "" : " (unused)", BLOCK_ABSTRACT (scope) ? " (abstract)": ""); if (BLOCK_SOURCE_LOCATION (scope) != UNKNOWN_LOCATION) { expanded_location s = expand_location (BLOCK_SOURCE_LOCATION (scope)); fprintf (file, " %s:%i", s.file, s.line); } if (BLOCK_ABSTRACT_ORIGIN (scope)) { tree origin = block_ultimate_origin (scope); if (origin) { fprintf (file, " Originating from :"); if (DECL_P (origin)) print_generic_decl (file, origin, flags); else fprintf (file, "#%i", BLOCK_NUMBER (origin)); } } fprintf (file, " \n"); for (var = BLOCK_VARS (scope); var; var = TREE_CHAIN (var)) { bool used = false; var_ann_t ann; if ((ann = var_ann (var)) && ann->used) used = true; fprintf (file, "%*s",indent, ""); print_generic_decl (file, var, flags); fprintf (file, "%s\n", used ? "" : " (unused)"); } for (i = 0; i < BLOCK_NUM_NONLOCALIZED_VARS (scope); i++) { fprintf (file, "%*s",indent, ""); print_generic_decl (file, BLOCK_NONLOCALIZED_VAR (scope, i), flags); fprintf (file, " (nonlocalized)\n"); } for (t = BLOCK_SUBBLOCKS (scope); t ; t = BLOCK_CHAIN (t)) dump_scope_block (file, indent + 2, t, flags); fprintf (file, "\n%*s}\n",indent, ""); } /* Dump the tree of lexical scopes starting at SCOPE to stderr. FLAGS is as in print_generic_expr. */ void debug_scope_block (tree scope, int flags) { dump_scope_block (stderr, 0, scope, flags); } /* Dump the tree of lexical scopes of current_function_decl to FILE. FLAGS is as in print_generic_expr. */ void dump_scope_blocks (FILE *file, int flags) { dump_scope_block (file, 0, DECL_INITIAL (current_function_decl), flags); } /* Dump the tree of lexical scopes of current_function_decl to stderr. FLAGS is as in print_generic_expr. */ void debug_scope_blocks (int flags) { dump_scope_blocks (stderr, flags); } /* Remove local variables that are not referenced in the IL. */ void remove_unused_locals (void) { basic_block bb; tree t, *cell; referenced_var_iterator rvi; var_ann_t ann; bitmap global_unused_vars = NULL; /* Removing declarations from lexical blocks when not optimizing is not only a waste of time, it actually causes differences in stack layout. */ if (!optimize) return; mark_scope_block_unused (DECL_INITIAL (current_function_decl)); /* Assume all locals are unused. */ FOR_EACH_REFERENCED_VAR (t, rvi) var_ann (t)->used = false; /* Walk the CFG marking all referenced symbols. */ FOR_EACH_BB (bb) { gimple_stmt_iterator gsi; size_t i; edge_iterator ei; edge e; /* Walk the statements. */ for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) { gimple stmt = gsi_stmt (gsi); tree b = gimple_block (stmt); if (is_gimple_debug (stmt)) continue; if (b) TREE_USED (b) = true; for (i = 0; i < gimple_num_ops (stmt); i++) mark_all_vars_used (gimple_op_ptr (gsi_stmt (gsi), i), NULL); } for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) { use_operand_p arg_p; ssa_op_iter i; tree def; gimple phi = gsi_stmt (gsi); /* No point processing globals. */ if (is_global_var (SSA_NAME_VAR (gimple_phi_result (phi)))) continue; def = gimple_phi_result (phi); mark_all_vars_used (&def, NULL); FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_ALL_USES) { tree arg = USE_FROM_PTR (arg_p); mark_all_vars_used (&arg, NULL); } } FOR_EACH_EDGE (e, ei, bb->succs) if (e->goto_locus) TREE_USED (e->goto_block) = true; } cfun->has_local_explicit_reg_vars = false; /* Remove unmarked local vars from local_decls. */ for (cell = &cfun->local_decls; *cell; ) { tree var = TREE_VALUE (*cell); if (TREE_CODE (var) != FUNCTION_DECL && (!(ann = var_ann (var)) || !ann->used)) { if (is_global_var (var)) { if (global_unused_vars == NULL) global_unused_vars = BITMAP_ALLOC (NULL); bitmap_set_bit (global_unused_vars, DECL_UID (var)); } else { *cell = TREE_CHAIN (*cell); continue; } } else if (TREE_CODE (var) == VAR_DECL && DECL_HARD_REGISTER (var) && !is_global_var (var)) cfun->has_local_explicit_reg_vars = true; cell = &TREE_CHAIN (*cell); } /* Remove unmarked global vars from local_decls. */ if (global_unused_vars != NULL) { for (t = cfun->local_decls; t; t = TREE_CHAIN (t)) { tree var = TREE_VALUE (t); if (TREE_CODE (var) == VAR_DECL && is_global_var (var) && (ann = var_ann (var)) != NULL && ann->used) mark_all_vars_used (&DECL_INITIAL (var), global_unused_vars); } for (cell = &cfun->local_decls; *cell; ) { tree var = TREE_VALUE (*cell); if (TREE_CODE (var) == VAR_DECL && is_global_var (var) && bitmap_bit_p (global_unused_vars, DECL_UID (var))) *cell = TREE_CHAIN (*cell); else cell = &TREE_CHAIN (*cell); } BITMAP_FREE (global_unused_vars); } /* Remove unused variables from REFERENCED_VARs. As a special exception keep the variables that are believed to be aliased. Those can't be easily removed from the alias sets and operand caches. They will be removed shortly after the next may_alias pass is performed. */ FOR_EACH_REFERENCED_VAR (t, rvi) if (!is_global_var (t) && TREE_CODE (t) != PARM_DECL && TREE_CODE (t) != RESULT_DECL && !(ann = var_ann (t))->used && !ann->is_heapvar && !TREE_ADDRESSABLE (t)) remove_referenced_var (t); remove_unused_scope_block_p (DECL_INITIAL (current_function_decl)); if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "Scope blocks after cleanups:\n"); dump_scope_blocks (dump_file, dump_flags); } } /* Allocate and return a new live range information object base on MAP. */ static tree_live_info_p new_tree_live_info (var_map map) { tree_live_info_p live; unsigned x; live = (tree_live_info_p) xmalloc (sizeof (struct tree_live_info_d)); live->map = map; live->num_blocks = last_basic_block; live->livein = (bitmap *)xmalloc (last_basic_block * sizeof (bitmap)); for (x = 0; x < (unsigned)last_basic_block; x++) live->livein[x] = BITMAP_ALLOC (NULL); live->liveout = (bitmap *)xmalloc (last_basic_block * sizeof (bitmap)); for (x = 0; x < (unsigned)last_basic_block; x++) live->liveout[x] = BITMAP_ALLOC (NULL); live->work_stack = XNEWVEC (int, last_basic_block); live->stack_top = live->work_stack; live->global = BITMAP_ALLOC (NULL); return live; } /* Free storage for live range info object LIVE. */ void delete_tree_live_info (tree_live_info_p live) { int x; BITMAP_FREE (live->global); free (live->work_stack); for (x = live->num_blocks - 1; x >= 0; x--) BITMAP_FREE (live->liveout[x]); free (live->liveout); for (x = live->num_blocks - 1; x >= 0; x--) BITMAP_FREE (live->livein[x]); free (live->livein); free (live); } /* Visit basic block BB and propagate any required live on entry bits from LIVE into the predecessors. VISITED is the bitmap of visited blocks. TMP is a temporary work bitmap which is passed in to avoid reallocating it each time. */ static void loe_visit_block (tree_live_info_p live, basic_block bb, sbitmap visited, bitmap tmp) { edge e; bool change; edge_iterator ei; basic_block pred_bb; bitmap loe; gcc_assert (!TEST_BIT (visited, bb->index)); SET_BIT (visited, bb->index); loe = live_on_entry (live, bb); FOR_EACH_EDGE (e, ei, bb->preds) { pred_bb = e->src; if (pred_bb == ENTRY_BLOCK_PTR) continue; /* TMP is variables live-on-entry from BB that aren't defined in the predecessor block. This should be the live on entry vars to pred. Note that liveout is the DEFs in a block while live on entry is being calculated. */ bitmap_and_compl (tmp, loe, live->liveout[pred_bb->index]); /* Add these bits to live-on-entry for the pred. if there are any changes, and pred_bb has been visited already, add it to the revisit stack. */ change = bitmap_ior_into (live_on_entry (live, pred_bb), tmp); if (TEST_BIT (visited, pred_bb->index) && change) { RESET_BIT (visited, pred_bb->index); *(live->stack_top)++ = pred_bb->index; } } } /* Using LIVE, fill in all the live-on-entry blocks between the defs and uses of all the variables. */ static void live_worklist (tree_live_info_p live) { unsigned b; basic_block bb; sbitmap visited = sbitmap_alloc (last_basic_block + 1); bitmap tmp = BITMAP_ALLOC (NULL); sbitmap_zero (visited); /* Visit all the blocks in reverse order and propagate live on entry values into the predecessors blocks. */ FOR_EACH_BB_REVERSE (bb) loe_visit_block (live, bb, visited, tmp); /* Process any blocks which require further iteration. */ while (live->stack_top != live->work_stack) { b = *--(live->stack_top); loe_visit_block (live, BASIC_BLOCK (b), visited, tmp); } BITMAP_FREE (tmp); sbitmap_free (visited); } /* Calculate the initial live on entry vector for SSA_NAME using immediate_use links. Set the live on entry fields in LIVE. Def's are marked temporarily in the liveout vector. */ static void set_var_live_on_entry (tree ssa_name, tree_live_info_p live) { int p; gimple stmt; use_operand_p use; basic_block def_bb = NULL; imm_use_iterator imm_iter; bool global = false; p = var_to_partition (live->map, ssa_name); if (p == NO_PARTITION) return; stmt = SSA_NAME_DEF_STMT (ssa_name); if (stmt) { def_bb = gimple_bb (stmt); /* Mark defs in liveout bitmap temporarily. */ if (def_bb) bitmap_set_bit (live->liveout[def_bb->index], p); } else def_bb = ENTRY_BLOCK_PTR; /* Visit each use of SSA_NAME and if it isn't in the same block as the def, add it to the list of live on entry blocks. */ FOR_EACH_IMM_USE_FAST (use, imm_iter, ssa_name) { gimple use_stmt = USE_STMT (use); basic_block add_block = NULL; if (gimple_code (use_stmt) == GIMPLE_PHI) { /* Uses in PHI's are considered to be live at exit of the SRC block as this is where a copy would be inserted. Check to see if it is defined in that block, or whether its live on entry. */ int index = PHI_ARG_INDEX_FROM_USE (use); edge e = gimple_phi_arg_edge (use_stmt, index); if (e->src != ENTRY_BLOCK_PTR) { if (e->src != def_bb) add_block = e->src; } } else if (is_gimple_debug (use_stmt)) continue; else { /* If its not defined in this block, its live on entry. */ basic_block use_bb = gimple_bb (use_stmt); if (use_bb != def_bb) add_block = use_bb; } /* If there was a live on entry use, set the bit. */ if (add_block) { global = true; bitmap_set_bit (live->livein[add_block->index], p); } } /* If SSA_NAME is live on entry to at least one block, fill in all the live on entry blocks between the def and all the uses. */ if (global) bitmap_set_bit (live->global, p); } /* Calculate the live on exit vectors based on the entry info in LIVEINFO. */ void calculate_live_on_exit (tree_live_info_p liveinfo) { basic_block bb; edge e; edge_iterator ei; /* live on entry calculations used liveout vectors for defs, clear them. */ FOR_EACH_BB (bb) bitmap_clear (liveinfo->liveout[bb->index]); /* Set all the live-on-exit bits for uses in PHIs. */ FOR_EACH_BB (bb) { gimple_stmt_iterator gsi; size_t i; /* Mark the PHI arguments which are live on exit to the pred block. */ for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) { gimple phi = gsi_stmt (gsi); for (i = 0; i < gimple_phi_num_args (phi); i++) { tree t = PHI_ARG_DEF (phi, i); int p; if (TREE_CODE (t) != SSA_NAME) continue; p = var_to_partition (liveinfo->map, t); if (p == NO_PARTITION) continue; e = gimple_phi_arg_edge (phi, i); if (e->src != ENTRY_BLOCK_PTR) bitmap_set_bit (liveinfo->liveout[e->src->index], p); } } /* Add each successors live on entry to this bock live on exit. */ FOR_EACH_EDGE (e, ei, bb->succs) if (e->dest != EXIT_BLOCK_PTR) bitmap_ior_into (liveinfo->liveout[bb->index], live_on_entry (liveinfo, e->dest)); } } /* Given partition map MAP, calculate all the live on entry bitmaps for each partition. Return a new live info object. */ tree_live_info_p calculate_live_ranges (var_map map) { tree var; unsigned i; tree_live_info_p live; live = new_tree_live_info (map); for (i = 0; i < num_var_partitions (map); i++) { var = partition_to_var (map, i); if (var != NULL_TREE) set_var_live_on_entry (var, live); } live_worklist (live); #ifdef ENABLE_CHECKING verify_live_on_entry (live); #endif calculate_live_on_exit (live); return live; } /* Output partition map MAP to file F. */ void dump_var_map (FILE *f, var_map map) { int t; unsigned x, y; int p; fprintf (f, "\nPartition map \n\n"); for (x = 0; x < map->num_partitions; x++) { if (map->view_to_partition != NULL) p = map->view_to_partition[x]; else p = x; if (ssa_name (p) == NULL_TREE) continue; t = 0; for (y = 1; y < num_ssa_names; y++) { p = partition_find (map->var_partition, y); if (map->partition_to_view) p = map->partition_to_view[p]; if (p == (int)x) { if (t++ == 0) { fprintf(f, "Partition %d (", x); print_generic_expr (f, partition_to_var (map, p), TDF_SLIM); fprintf (f, " - "); } fprintf (f, "%d ", y); } } if (t != 0) fprintf (f, ")\n"); } fprintf (f, "\n"); } /* Output live range info LIVE to file F, controlled by FLAG. */ void dump_live_info (FILE *f, tree_live_info_p live, int flag) { basic_block bb; unsigned i; var_map map = live->map; bitmap_iterator bi; if ((flag & LIVEDUMP_ENTRY) && live->livein) { FOR_EACH_BB (bb) { fprintf (f, "\nLive on entry to BB%d : ", bb->index); EXECUTE_IF_SET_IN_BITMAP (live->livein[bb->index], 0, i, bi) { print_generic_expr (f, partition_to_var (map, i), TDF_SLIM); fprintf (f, " "); } fprintf (f, "\n"); } } if ((flag & LIVEDUMP_EXIT) && live->liveout) { FOR_EACH_BB (bb) { fprintf (f, "\nLive on exit from BB%d : ", bb->index); EXECUTE_IF_SET_IN_BITMAP (live->liveout[bb->index], 0, i, bi) { print_generic_expr (f, partition_to_var (map, i), TDF_SLIM); fprintf (f, " "); } fprintf (f, "\n"); } } } #ifdef ENABLE_CHECKING /* Verify that SSA_VAR is a non-virtual SSA_NAME. */ void register_ssa_partition_check (tree ssa_var) { gcc_assert (TREE_CODE (ssa_var) == SSA_NAME); if (!is_gimple_reg (SSA_NAME_VAR (ssa_var))) { fprintf (stderr, "Illegally registering a virtual SSA name :"); print_generic_expr (stderr, ssa_var, TDF_SLIM); fprintf (stderr, " in the SSA->Normal phase.\n"); internal_error ("SSA corruption"); } } /* Verify that the info in LIVE matches the current cfg. */ static void verify_live_on_entry (tree_live_info_p live) { unsigned i; tree var; gimple stmt; basic_block bb; edge e; int num; edge_iterator ei; var_map map = live->map; /* Check for live on entry partitions and report those with a DEF in the program. This will typically mean an optimization has done something wrong. */ bb = ENTRY_BLOCK_PTR; num = 0; FOR_EACH_EDGE (e, ei, bb->succs) { int entry_block = e->dest->index; if (e->dest == EXIT_BLOCK_PTR) continue; for (i = 0; i < (unsigned)num_var_partitions (map); i++) { basic_block tmp; tree d; bitmap loe; var = partition_to_var (map, i); stmt = SSA_NAME_DEF_STMT (var); tmp = gimple_bb (stmt); d = gimple_default_def (cfun, SSA_NAME_VAR (var)); loe = live_on_entry (live, e->dest); if (loe && bitmap_bit_p (loe, i)) { if (!gimple_nop_p (stmt)) { num++; print_generic_expr (stderr, var, TDF_SLIM); fprintf (stderr, " is defined "); if (tmp) fprintf (stderr, " in BB%d, ", tmp->index); fprintf (stderr, "by:\n"); print_gimple_stmt (stderr, stmt, 0, TDF_SLIM); fprintf (stderr, "\nIt is also live-on-entry to entry BB %d", entry_block); fprintf (stderr, " So it appears to have multiple defs.\n"); } else { if (d != var) { num++; print_generic_expr (stderr, var, TDF_SLIM); fprintf (stderr, " is live-on-entry to BB%d ", entry_block); if (d) { fprintf (stderr, " but is not the default def of "); print_generic_expr (stderr, d, TDF_SLIM); fprintf (stderr, "\n"); } else fprintf (stderr, " and there is no default def.\n"); } } } else if (d == var) { /* The only way this var shouldn't be marked live on entry is if it occurs in a PHI argument of the block. */ size_t z; bool ok = false; gimple_stmt_iterator gsi; for (gsi = gsi_start_phis (e->dest); !gsi_end_p (gsi) && !ok; gsi_next (&gsi)) { gimple phi = gsi_stmt (gsi); for (z = 0; z < gimple_phi_num_args (phi); z++) if (var == gimple_phi_arg_def (phi, z)) { ok = true; break; } } if (ok) continue; num++; print_generic_expr (stderr, var, TDF_SLIM); fprintf (stderr, " is not marked live-on-entry to entry BB%d ", entry_block); fprintf (stderr, "but it is a default def so it should be.\n"); } } } gcc_assert (num <= 0); } #endif
Go to most recent revision | Compare with Previous | Blame | View Log