1 /* Miscellaneous SSA utility functions.
2 Copyright (C) 2001, 2002, 2003, 2004, 2005, 2007, 2008, 2009, 2010, 2011
3 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
30 #include "langhooks.h"
31 #include "basic-block.h"
34 #include "tree-pretty-print.h"
35 #include "gimple-pretty-print.h"
37 #include "pointer-set.h"
38 #include "tree-flow.h"
40 #include "tree-inline.h"
43 #include "tree-dump.h"
44 #include "tree-pass.h"
45 #include "diagnostic-core.h"
47 /* Pointer map of variable mappings, keyed by edge. */
48 static struct pointer_map_t *edge_var_maps;
51 /* Add a mapping with PHI RESULT and PHI DEF associated with edge E. */
54 redirect_edge_var_map_add (edge e, tree result, tree def, source_location locus)
57 edge_var_map_vector old_head, head;
58 edge_var_map new_node;
60 if (edge_var_maps == NULL)
61 edge_var_maps = pointer_map_create ();
63 slot = pointer_map_insert (edge_var_maps, e);
64 old_head = head = (edge_var_map_vector) *slot;
67 head = VEC_alloc (edge_var_map, heap, 5);
71 new_node.result = result;
72 new_node.locus = locus;
74 VEC_safe_push (edge_var_map, heap, head, &new_node);
77 /* The push did some reallocation. Update the pointer map. */
83 /* Clear the var mappings in edge E. */
86 redirect_edge_var_map_clear (edge e)
89 edge_var_map_vector head;
94 slot = pointer_map_contains (edge_var_maps, e);
98 head = (edge_var_map_vector) *slot;
99 VEC_free (edge_var_map, heap, head);
105 /* Duplicate the redirected var mappings in OLDE in NEWE.
107 Since we can't remove a mapping, let's just duplicate it. This assumes a
108 pointer_map can have multiple edges mapping to the same var_map (many to
109 one mapping), since we don't remove the previous mappings. */
112 redirect_edge_var_map_dup (edge newe, edge olde)
114 void **new_slot, **old_slot;
115 edge_var_map_vector head;
120 new_slot = pointer_map_insert (edge_var_maps, newe);
121 old_slot = pointer_map_contains (edge_var_maps, olde);
124 head = (edge_var_map_vector) *old_slot;
127 *new_slot = VEC_copy (edge_var_map, heap, head);
129 *new_slot = VEC_alloc (edge_var_map, heap, 5);
133 /* Return the variable mappings for a given edge. If there is none, return
137 redirect_edge_var_map_vector (edge e)
141 /* Hey, what kind of idiot would... you'd be surprised. */
145 slot = pointer_map_contains (edge_var_maps, e);
149 return (edge_var_map_vector) *slot;
152 /* Used by redirect_edge_var_map_destroy to free all memory. */
155 free_var_map_entry (const void *key ATTRIBUTE_UNUSED,
157 void *data ATTRIBUTE_UNUSED)
159 edge_var_map_vector head = (edge_var_map_vector) *value;
160 VEC_free (edge_var_map, heap, head);
164 /* Clear the edge variable mappings. */
167 redirect_edge_var_map_destroy (void)
171 pointer_map_traverse (edge_var_maps, free_var_map_entry, NULL);
172 pointer_map_destroy (edge_var_maps);
173 edge_var_maps = NULL;
178 /* Remove the corresponding arguments from the PHI nodes in E's
179 destination block and redirect it to DEST. Return redirected edge.
180 The list of removed arguments is stored in a vector accessed
181 through edge_var_maps. */
184 ssa_redirect_edge (edge e, basic_block dest)
186 gimple_stmt_iterator gsi;
189 redirect_edge_var_map_clear (e);
191 /* Remove the appropriate PHI arguments in E's destination block. */
192 for (gsi = gsi_start_phis (e->dest); !gsi_end_p (gsi); gsi_next (&gsi))
195 source_location locus ;
197 phi = gsi_stmt (gsi);
198 def = gimple_phi_arg_def (phi, e->dest_idx);
199 locus = gimple_phi_arg_location (phi, e->dest_idx);
201 if (def == NULL_TREE)
204 redirect_edge_var_map_add (e, gimple_phi_result (phi), def, locus);
207 e = redirect_edge_succ_nodup (e, dest);
213 /* Add PHI arguments queued in PENDING_STMT list on edge E to edge
217 flush_pending_stmts (edge e)
220 edge_var_map_vector v;
223 gimple_stmt_iterator gsi;
225 v = redirect_edge_var_map_vector (e);
229 for (gsi = gsi_start_phis (e->dest), i = 0;
230 !gsi_end_p (gsi) && VEC_iterate (edge_var_map, v, i, vm);
231 gsi_next (&gsi), i++)
235 phi = gsi_stmt (gsi);
236 def = redirect_edge_var_map_def (vm);
237 add_phi_arg (phi, def, e, redirect_edge_var_map_location (vm));
240 redirect_edge_var_map_clear (e);
243 /* Given a tree for an expression for which we might want to emit
244 locations or values in debug information (generally a variable, but
245 we might deal with other kinds of trees in the future), return the
246 tree that should be used as the variable of a DEBUG_BIND STMT or
247 VAR_LOCATION INSN or NOTE. Return NULL if VAR is not to be tracked. */
250 target_for_debug_bind (tree var)
252 if (!MAY_HAVE_DEBUG_STMTS)
255 if (TREE_CODE (var) != VAR_DECL
256 && TREE_CODE (var) != PARM_DECL)
259 if (DECL_HAS_VALUE_EXPR_P (var))
260 return target_for_debug_bind (DECL_VALUE_EXPR (var));
262 if (DECL_IGNORED_P (var))
265 if (!is_gimple_reg (var))
271 /* Called via walk_tree, look for SSA_NAMEs that have already been
275 find_released_ssa_name (tree *tp, int *walk_subtrees, void *data_)
277 struct walk_stmt_info *wi = (struct walk_stmt_info *) data_;
279 if (wi && wi->is_lhs)
282 if (TREE_CODE (*tp) == SSA_NAME)
284 if (SSA_NAME_IN_FREE_LIST (*tp))
289 else if (IS_TYPE_OR_DECL_P (*tp))
295 /* Insert a DEBUG BIND stmt before the DEF of VAR if VAR is referenced
296 by other DEBUG stmts, and replace uses of the DEF with the
297 newly-created debug temp. */
300 insert_debug_temp_for_var_def (gimple_stmt_iterator *gsi, tree var)
302 imm_use_iterator imm_iter;
305 gimple def_stmt = NULL;
309 if (!MAY_HAVE_DEBUG_STMTS)
312 /* If this name has already been registered for replacement, do nothing
313 as anything that uses this name isn't in SSA form. */
314 if (name_registered_for_update_p (var))
317 /* Check whether there are debug stmts that reference this variable and,
318 if there are, decide whether we should use a debug temp. */
319 FOR_EACH_IMM_USE_FAST (use_p, imm_iter, var)
321 stmt = USE_STMT (use_p);
323 if (!gimple_debug_bind_p (stmt))
329 if (gimple_debug_bind_get_value (stmt) != var)
331 /* Count this as an additional use, so as to make sure we
332 use a temp unless VAR's definition has a SINGLE_RHS that
343 def_stmt = gsi_stmt (*gsi);
345 def_stmt = SSA_NAME_DEF_STMT (var);
347 /* If we didn't get an insertion point, and the stmt has already
348 been removed, we won't be able to insert the debug bind stmt, so
349 we'll have to drop debug information. */
350 if (gimple_code (def_stmt) == GIMPLE_PHI)
352 value = degenerate_phi_result (def_stmt);
353 if (value && walk_tree (&value, find_released_ssa_name, NULL, NULL))
355 /* error_mark_node is what fixup_noreturn_call changes PHI arguments
357 else if (value == error_mark_node)
360 else if (is_gimple_assign (def_stmt))
362 bool no_value = false;
364 if (!dom_info_available_p (CDI_DOMINATORS))
366 struct walk_stmt_info wi;
368 memset (&wi, 0, sizeof (wi));
370 /* When removing blocks without following reverse dominance
371 order, we may sometimes encounter SSA_NAMEs that have
372 already been released, referenced in other SSA_DEFs that
373 we're about to release. Consider:
382 If we deleted BB X first, propagating the value of w_2
383 won't do us any good. It's too late to recover their
384 original definition of v_1: when it was deleted, it was
385 only referenced in other DEFs, it couldn't possibly know
386 it should have been retained, and propagating every
387 single DEF just in case it might have to be propagated
388 into a DEBUG STMT would probably be too wasteful.
390 When dominator information is not readily available, we
391 check for and accept some loss of debug information. But
392 if it is available, there's no excuse for us to remove
393 blocks in the wrong order, so we don't even check for
394 dead SSA NAMEs. SSA verification shall catch any
396 if ((!gsi && !gimple_bb (def_stmt))
397 || walk_gimple_op (def_stmt, find_released_ssa_name, &wi))
402 value = gimple_assign_rhs_to_tree (def_stmt);
407 /* If there's a single use of VAR, and VAR is the entire debug
408 expression (usecount would have been incremented again
409 otherwise), and the definition involves only constants and
410 SSA names, then we can propagate VALUE into this single use,
413 We can also avoid using a temp if VALUE can be shared and
414 propagated into all uses, without generating expressions that
415 wouldn't be valid gimple RHSs.
417 Other cases that would require unsharing or non-gimple RHSs
418 are deferred to a debug temp, although we could avoid temps
419 at the expense of duplication of expressions. */
421 if (CONSTANT_CLASS_P (value)
422 || gimple_code (def_stmt) == GIMPLE_PHI
424 && (!gimple_assign_single_p (def_stmt)
425 || is_gimple_min_invariant (value)))
426 || is_gimple_reg (value))
427 value = unshare_expr (value);
431 tree vexpr = make_node (DEBUG_EXPR_DECL);
433 def_temp = gimple_build_debug_bind (vexpr,
434 unshare_expr (value),
437 DECL_ARTIFICIAL (vexpr) = 1;
438 TREE_TYPE (vexpr) = TREE_TYPE (value);
440 DECL_MODE (vexpr) = DECL_MODE (value);
442 DECL_MODE (vexpr) = TYPE_MODE (TREE_TYPE (value));
445 gsi_insert_before (gsi, def_temp, GSI_SAME_STMT);
448 gimple_stmt_iterator ngsi = gsi_for_stmt (def_stmt);
449 gsi_insert_before (&ngsi, def_temp, GSI_SAME_STMT);
456 FOR_EACH_IMM_USE_STMT (stmt, imm_iter, var)
458 if (!gimple_debug_bind_p (stmt))
463 FOR_EACH_IMM_USE_ON_STMT (use_p, imm_iter)
464 /* unshare_expr is not needed here. vexpr is either a
465 SINGLE_RHS, that can be safely shared, some other RHS
466 that was unshared when we found it had a single debug
467 use, or a DEBUG_EXPR_DECL, that can be safely
469 SET_USE (use_p, value);
470 /* If we didn't replace uses with a debug decl fold the
471 resulting expression. Otherwise we end up with invalid IL. */
472 if (TREE_CODE (value) != DEBUG_EXPR_DECL)
473 fold_stmt_inplace (stmt);
476 gimple_debug_bind_reset_value (stmt);
483 /* Insert a DEBUG BIND stmt before STMT for each DEF referenced by
484 other DEBUG stmts, and replace uses of the DEF with the
485 newly-created debug temp. */
488 insert_debug_temps_for_defs (gimple_stmt_iterator *gsi)
494 if (!MAY_HAVE_DEBUG_STMTS)
497 stmt = gsi_stmt (*gsi);
499 FOR_EACH_PHI_OR_STMT_DEF (def_p, stmt, op_iter, SSA_OP_DEF)
501 tree var = DEF_FROM_PTR (def_p);
503 if (TREE_CODE (var) != SSA_NAME)
506 insert_debug_temp_for_var_def (gsi, var);
510 /* Delete SSA DEFs for SSA versions in the TOREMOVE bitmap, removing
511 dominated stmts before their dominators, so that release_ssa_defs
512 stands a chance of propagating DEFs into debug bind stmts. */
515 release_defs_bitset (bitmap toremove)
520 /* Performing a topological sort is probably overkill, this will
521 most likely run in slightly superlinear time, rather than the
522 pathological quadratic worst case. */
523 while (!bitmap_empty_p (toremove))
524 EXECUTE_IF_SET_IN_BITMAP (toremove, 0, j, bi)
526 bool remove_now = true;
527 tree var = ssa_name (j);
529 imm_use_iterator uit;
531 FOR_EACH_IMM_USE_STMT (stmt, uit, var)
536 /* We can't propagate PHI nodes into debug stmts. */
537 if (gimple_code (stmt) == GIMPLE_PHI
538 || is_gimple_debug (stmt))
541 /* If we find another definition to remove that uses
542 the one we're looking at, defer the removal of this
543 one, so that it can be propagated into debug stmts
544 after the other is. */
545 FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, dit, SSA_OP_DEF)
547 tree odef = DEF_FROM_PTR (def_p);
549 if (bitmap_bit_p (toremove, SSA_NAME_VERSION (odef)))
557 BREAK_FROM_IMM_USE_STMT (uit);
562 gimple def = SSA_NAME_DEF_STMT (var);
563 gimple_stmt_iterator gsi = gsi_for_stmt (def);
565 if (gimple_code (def) == GIMPLE_PHI)
566 remove_phi_node (&gsi, true);
569 gsi_remove (&gsi, true);
573 bitmap_clear_bit (toremove, j);
578 /* Return true if SSA_NAME is malformed and mark it visited.
580 IS_VIRTUAL is true if this SSA_NAME was found inside a virtual
584 verify_ssa_name (tree ssa_name, bool is_virtual)
586 if (TREE_CODE (ssa_name) != SSA_NAME)
588 error ("expected an SSA_NAME object");
592 if (TREE_TYPE (ssa_name) != TREE_TYPE (SSA_NAME_VAR (ssa_name)))
594 error ("type mismatch between an SSA_NAME and its symbol");
598 if (SSA_NAME_IN_FREE_LIST (ssa_name))
600 error ("found an SSA_NAME that had been released into the free pool");
604 if (is_virtual && is_gimple_reg (ssa_name))
606 error ("found a virtual definition for a GIMPLE register");
610 if (is_virtual && SSA_NAME_VAR (ssa_name) != gimple_vop (cfun))
612 error ("virtual SSA name for non-VOP decl");
616 if (!is_virtual && !is_gimple_reg (ssa_name))
618 error ("found a real definition for a non-register");
622 if (SSA_NAME_IS_DEFAULT_DEF (ssa_name)
623 && !gimple_nop_p (SSA_NAME_DEF_STMT (ssa_name)))
625 error ("found a default name with a non-empty defining statement");
633 /* Return true if the definition of SSA_NAME at block BB is malformed.
635 STMT is the statement where SSA_NAME is created.
637 DEFINITION_BLOCK is an array of basic blocks indexed by SSA_NAME
638 version numbers. If DEFINITION_BLOCK[SSA_NAME_VERSION] is set,
639 it means that the block in that array slot contains the
640 definition of SSA_NAME.
642 IS_VIRTUAL is true if SSA_NAME is created by a VDEF. */
645 verify_def (basic_block bb, basic_block *definition_block, tree ssa_name,
646 gimple stmt, bool is_virtual)
648 if (verify_ssa_name (ssa_name, is_virtual))
651 if (TREE_CODE (SSA_NAME_VAR (ssa_name)) == RESULT_DECL
652 && DECL_BY_REFERENCE (SSA_NAME_VAR (ssa_name)))
654 error ("RESULT_DECL should be read only when DECL_BY_REFERENCE is set");
658 if (definition_block[SSA_NAME_VERSION (ssa_name)])
660 error ("SSA_NAME created in two different blocks %i and %i",
661 definition_block[SSA_NAME_VERSION (ssa_name)]->index, bb->index);
665 definition_block[SSA_NAME_VERSION (ssa_name)] = bb;
667 if (SSA_NAME_DEF_STMT (ssa_name) != stmt)
669 error ("SSA_NAME_DEF_STMT is wrong");
670 fprintf (stderr, "Expected definition statement:\n");
671 print_gimple_stmt (stderr, SSA_NAME_DEF_STMT (ssa_name), 4, TDF_VOPS);
672 fprintf (stderr, "\nActual definition statement:\n");
673 print_gimple_stmt (stderr, stmt, 4, TDF_VOPS);
680 fprintf (stderr, "while verifying SSA_NAME ");
681 print_generic_expr (stderr, ssa_name, 0);
682 fprintf (stderr, " in statement\n");
683 print_gimple_stmt (stderr, stmt, 4, TDF_VOPS);
689 /* Return true if the use of SSA_NAME at statement STMT in block BB is
692 DEF_BB is the block where SSA_NAME was found to be created.
694 IDOM contains immediate dominator information for the flowgraph.
696 CHECK_ABNORMAL is true if the caller wants to check whether this use
697 is flowing through an abnormal edge (only used when checking PHI
700 If NAMES_DEFINED_IN_BB is not NULL, it contains a bitmap of ssa names
701 that are defined before STMT in basic block BB. */
704 verify_use (basic_block bb, basic_block def_bb, use_operand_p use_p,
705 gimple stmt, bool check_abnormal, bitmap names_defined_in_bb)
708 tree ssa_name = USE_FROM_PTR (use_p);
710 if (!TREE_VISITED (ssa_name))
711 if (verify_imm_links (stderr, ssa_name))
714 TREE_VISITED (ssa_name) = 1;
716 if (gimple_nop_p (SSA_NAME_DEF_STMT (ssa_name))
717 && SSA_NAME_IS_DEFAULT_DEF (ssa_name))
718 ; /* Default definitions have empty statements. Nothing to do. */
721 error ("missing definition");
724 else if (bb != def_bb
725 && !dominated_by_p (CDI_DOMINATORS, bb, def_bb))
727 error ("definition in block %i does not dominate use in block %i",
728 def_bb->index, bb->index);
731 else if (bb == def_bb
732 && names_defined_in_bb != NULL
733 && !bitmap_bit_p (names_defined_in_bb, SSA_NAME_VERSION (ssa_name)))
735 error ("definition in block %i follows the use", def_bb->index);
740 && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (ssa_name))
742 error ("SSA_NAME_OCCURS_IN_ABNORMAL_PHI should be set");
746 /* Make sure the use is in an appropriate list by checking the previous
747 element to make sure it's the same. */
748 if (use_p->prev == NULL)
750 error ("no immediate_use list");
756 if (use_p->prev->use == NULL)
757 listvar = use_p->prev->loc.ssa_name;
759 listvar = USE_FROM_PTR (use_p->prev);
760 if (listvar != ssa_name)
762 error ("wrong immediate use list");
769 fprintf (stderr, "for SSA_NAME: ");
770 print_generic_expr (stderr, ssa_name, TDF_VOPS);
771 fprintf (stderr, " in statement:\n");
772 print_gimple_stmt (stderr, stmt, 0, TDF_VOPS);
779 /* Return true if any of the arguments for PHI node PHI at block BB is
782 DEFINITION_BLOCK is an array of basic blocks indexed by SSA_NAME
783 version numbers. If DEFINITION_BLOCK[SSA_NAME_VERSION] is set,
784 it means that the block in that array slot contains the
785 definition of SSA_NAME. */
788 verify_phi_args (gimple phi, basic_block bb, basic_block *definition_block)
792 size_t i, phi_num_args = gimple_phi_num_args (phi);
794 if (EDGE_COUNT (bb->preds) != phi_num_args)
796 error ("incoming edge count does not match number of PHI arguments");
801 for (i = 0; i < phi_num_args; i++)
803 use_operand_p op_p = gimple_phi_arg_imm_use_ptr (phi, i);
804 tree op = USE_FROM_PTR (op_p);
806 e = EDGE_PRED (bb, i);
810 error ("PHI argument is missing for edge %d->%d",
817 if (TREE_CODE (op) != SSA_NAME && !is_gimple_min_invariant (op))
819 error ("PHI argument is not SSA_NAME, or invariant");
823 if (TREE_CODE (op) == SSA_NAME)
825 err = verify_ssa_name (op, !is_gimple_reg (gimple_phi_result (phi)));
826 err |= verify_use (e->src, definition_block[SSA_NAME_VERSION (op)],
827 op_p, phi, e->flags & EDGE_ABNORMAL, NULL);
830 if (TREE_CODE (op) == ADDR_EXPR)
832 tree base = TREE_OPERAND (op, 0);
833 while (handled_component_p (base))
834 base = TREE_OPERAND (base, 0);
835 if ((TREE_CODE (base) == VAR_DECL
836 || TREE_CODE (base) == PARM_DECL
837 || TREE_CODE (base) == RESULT_DECL)
838 && !TREE_ADDRESSABLE (base))
840 error ("address taken, but ADDRESSABLE bit not set");
847 error ("wrong edge %d->%d for PHI argument",
848 e->src->index, e->dest->index);
854 fprintf (stderr, "PHI argument\n");
855 print_generic_stmt (stderr, op, TDF_VOPS);
863 fprintf (stderr, "for PHI node\n");
864 print_gimple_stmt (stderr, phi, 0, TDF_VOPS|TDF_MEMSYMS);
872 /* Verify common invariants in the SSA web.
873 TODO: verify the variable annotations. */
876 verify_ssa (bool check_modified_stmt)
880 basic_block *definition_block = XCNEWVEC (basic_block, num_ssa_names);
883 enum dom_state orig_dom_state = dom_info_state (CDI_DOMINATORS);
884 bitmap names_defined_in_bb = BITMAP_ALLOC (NULL);
886 gcc_assert (!need_ssa_update_p (cfun));
890 timevar_push (TV_TREE_SSA_VERIFY);
892 /* Keep track of SSA names present in the IL. */
893 for (i = 1; i < num_ssa_names; i++)
895 tree name = ssa_name (i);
899 TREE_VISITED (name) = 0;
901 stmt = SSA_NAME_DEF_STMT (name);
902 if (!gimple_nop_p (stmt))
904 basic_block bb = gimple_bb (stmt);
905 verify_def (bb, definition_block,
906 name, stmt, !is_gimple_reg (name));
912 calculate_dominance_info (CDI_DOMINATORS);
914 /* Now verify all the uses and make sure they agree with the definitions
915 found in the previous pass. */
921 gimple_stmt_iterator gsi;
923 /* Make sure that all edges have a clear 'aux' field. */
924 FOR_EACH_EDGE (e, ei, bb->preds)
928 error ("AUX pointer initialized for edge %d->%d", e->src->index,
934 /* Verify the arguments for every PHI node in the block. */
935 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
937 phi = gsi_stmt (gsi);
938 if (verify_phi_args (phi, bb, definition_block))
941 bitmap_set_bit (names_defined_in_bb,
942 SSA_NAME_VERSION (gimple_phi_result (phi)));
945 /* Now verify all the uses and vuses in every statement of the block. */
946 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
948 gimple stmt = gsi_stmt (gsi);
954 if (check_modified_stmt && gimple_modified_p (stmt))
956 error ("stmt (%p) marked modified after optimization pass: ",
958 print_gimple_stmt (stderr, stmt, 0, TDF_VOPS);
962 if (is_gimple_assign (stmt)
963 && TREE_CODE (gimple_assign_lhs (stmt)) != SSA_NAME)
965 tree lhs, base_address;
967 lhs = gimple_assign_lhs (stmt);
968 base_address = get_base_address (lhs);
971 && SSA_VAR_P (base_address)
972 && !gimple_vdef (stmt)
975 error ("statement makes a memory store, but has no VDEFS");
976 print_gimple_stmt (stderr, stmt, 0, TDF_VOPS);
980 else if (gimple_debug_bind_p (stmt)
981 && !gimple_debug_bind_has_value_p (stmt))
984 /* Verify the single virtual operand and its constraints. */
986 if (gimple_vdef (stmt))
988 if (gimple_vdef_op (stmt) == NULL_DEF_OPERAND_P)
990 error ("statement has VDEF operand not in defs list");
993 if (!gimple_vuse (stmt))
995 error ("statement has VDEF but no VUSE operand");
998 else if (SSA_NAME_VAR (gimple_vdef (stmt))
999 != SSA_NAME_VAR (gimple_vuse (stmt)))
1001 error ("VDEF and VUSE do not use the same symbol");
1004 has_err |= verify_ssa_name (gimple_vdef (stmt), true);
1006 if (gimple_vuse (stmt))
1008 if (gimple_vuse_op (stmt) == NULL_USE_OPERAND_P)
1010 error ("statement has VUSE operand not in uses list");
1013 has_err |= verify_ssa_name (gimple_vuse (stmt), true);
1017 error ("in statement");
1018 print_gimple_stmt (stderr, stmt, 0, TDF_VOPS|TDF_MEMSYMS);
1023 FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_USE|SSA_OP_DEF)
1025 if (verify_ssa_name (op, false))
1027 error ("in statement");
1028 print_gimple_stmt (stderr, stmt, 0, TDF_VOPS|TDF_MEMSYMS);
1034 for (i = 0; i < gimple_num_ops (stmt); i++)
1036 op = gimple_op (stmt, i);
1037 if (op && TREE_CODE (op) == SSA_NAME && --count < 0)
1039 error ("number of operands and imm-links don%'t agree"
1041 print_gimple_stmt (stderr, stmt, 0, TDF_VOPS|TDF_MEMSYMS);
1046 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE|SSA_OP_VUSE)
1048 op = USE_FROM_PTR (use_p);
1049 if (verify_use (bb, definition_block[SSA_NAME_VERSION (op)],
1050 use_p, stmt, false, names_defined_in_bb))
1054 FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_ALL_DEFS)
1056 if (SSA_NAME_DEF_STMT (op) != stmt)
1058 error ("SSA_NAME_DEF_STMT is wrong");
1059 fprintf (stderr, "Expected definition statement:\n");
1060 print_gimple_stmt (stderr, stmt, 4, TDF_VOPS);
1061 fprintf (stderr, "\nActual definition statement:\n");
1062 print_gimple_stmt (stderr, SSA_NAME_DEF_STMT (op),
1066 bitmap_set_bit (names_defined_in_bb, SSA_NAME_VERSION (op));
1070 bitmap_clear (names_defined_in_bb);
1073 free (definition_block);
1075 /* Restore the dominance information to its prior known state, so
1076 that we do not perturb the compiler's subsequent behavior. */
1077 if (orig_dom_state == DOM_NONE)
1078 free_dominance_info (CDI_DOMINATORS);
1080 set_dom_info_availability (CDI_DOMINATORS, orig_dom_state);
1082 BITMAP_FREE (names_defined_in_bb);
1083 timevar_pop (TV_TREE_SSA_VERIFY);
1087 internal_error ("verify_ssa failed");
1090 /* Return true if the uid in both int tree maps are equal. */
1093 int_tree_map_eq (const void *va, const void *vb)
1095 const struct int_tree_map *a = (const struct int_tree_map *) va;
1096 const struct int_tree_map *b = (const struct int_tree_map *) vb;
1097 return (a->uid == b->uid);
1100 /* Hash a UID in a int_tree_map. */
1103 int_tree_map_hash (const void *item)
1105 return ((const struct int_tree_map *)item)->uid;
1108 /* Return true if the DECL_UID in both trees are equal. */
1111 uid_decl_map_eq (const void *va, const void *vb)
1113 const_tree a = (const_tree) va;
1114 const_tree b = (const_tree) vb;
1115 return (a->decl_minimal.uid == b->decl_minimal.uid);
1118 /* Hash a tree in a uid_decl_map. */
1121 uid_decl_map_hash (const void *item)
1123 return ((const_tree)item)->decl_minimal.uid;
1126 /* Return true if the DECL_UID in both trees are equal. */
1129 uid_ssaname_map_eq (const void *va, const void *vb)
1131 const_tree a = (const_tree) va;
1132 const_tree b = (const_tree) vb;
1133 return (a->ssa_name.var->decl_minimal.uid == b->ssa_name.var->decl_minimal.uid);
1136 /* Hash a tree in a uid_decl_map. */
1139 uid_ssaname_map_hash (const void *item)
1141 return ((const_tree)item)->ssa_name.var->decl_minimal.uid;
1145 /* Initialize global DFA and SSA structures. */
1148 init_tree_ssa (struct function *fn)
1150 fn->gimple_df = ggc_alloc_cleared_gimple_df ();
1151 fn->gimple_df->referenced_vars = htab_create_ggc (20, uid_decl_map_hash,
1152 uid_decl_map_eq, NULL);
1153 fn->gimple_df->default_defs = htab_create_ggc (20, uid_ssaname_map_hash,
1154 uid_ssaname_map_eq, NULL);
1155 pt_solution_reset (&fn->gimple_df->escaped);
1156 init_ssanames (fn, 0);
1161 /* Deallocate memory associated with SSA data structures for FNDECL. */
1164 delete_tree_ssa (void)
1166 referenced_var_iterator rvi;
1169 /* Remove annotations from every referenced local variable. */
1170 FOR_EACH_REFERENCED_VAR (cfun, var, rvi)
1172 if (is_global_var (var))
1176 ggc_free (var_ann (var));
1177 *DECL_VAR_ANN_PTR (var) = NULL;
1180 htab_delete (gimple_referenced_vars (cfun));
1181 cfun->gimple_df->referenced_vars = NULL;
1186 /* We no longer maintain the SSA operand cache at this point. */
1187 if (ssa_operands_active ())
1188 fini_ssa_operands ();
1190 delete_alias_heapvars ();
1192 htab_delete (cfun->gimple_df->default_defs);
1193 cfun->gimple_df->default_defs = NULL;
1194 pt_solution_reset (&cfun->gimple_df->escaped);
1195 if (cfun->gimple_df->decls_to_pointers != NULL)
1196 pointer_map_destroy (cfun->gimple_df->decls_to_pointers);
1197 cfun->gimple_df->decls_to_pointers = NULL;
1198 cfun->gimple_df->modified_noreturn_calls = NULL;
1199 cfun->gimple_df = NULL;
1201 /* We no longer need the edge variable maps. */
1202 redirect_edge_var_map_destroy ();
1205 /* Return true if the conversion from INNER_TYPE to OUTER_TYPE is a
1206 useless type conversion, otherwise return false.
1208 This function implicitly defines the middle-end type system. With
1209 the notion of 'a < b' meaning that useless_type_conversion_p (a, b)
1210 holds and 'a > b' meaning that useless_type_conversion_p (b, a) holds,
1211 the following invariants shall be fulfilled:
1213 1) useless_type_conversion_p is transitive.
1214 If a < b and b < c then a < c.
1216 2) useless_type_conversion_p is not symmetric.
1217 From a < b does not follow a > b.
1219 3) Types define the available set of operations applicable to values.
1220 A type conversion is useless if the operations for the target type
1221 is a subset of the operations for the source type. For example
1222 casts to void* are useless, casts from void* are not (void* can't
1223 be dereferenced or offsetted, but copied, hence its set of operations
1224 is a strict subset of that of all other data pointer types). Casts
1225 to const T* are useless (can't be written to), casts from const T*
1229 useless_type_conversion_p (tree outer_type, tree inner_type)
1231 /* Do the following before stripping toplevel qualifiers. */
1232 if (POINTER_TYPE_P (inner_type)
1233 && POINTER_TYPE_P (outer_type))
1235 /* Do not lose casts between pointers to different address spaces. */
1236 if (TYPE_ADDR_SPACE (TREE_TYPE (outer_type))
1237 != TYPE_ADDR_SPACE (TREE_TYPE (inner_type)))
1240 /* Do not lose casts to restrict qualified pointers. */
1241 if ((TYPE_RESTRICT (outer_type)
1242 != TYPE_RESTRICT (inner_type))
1243 && TYPE_RESTRICT (outer_type))
1246 /* If the outer type is (void *) or a pointer to an incomplete
1247 record type or a pointer to an unprototyped function,
1248 then the conversion is not necessary. */
1249 if (VOID_TYPE_P (TREE_TYPE (outer_type))
1250 || ((TREE_CODE (TREE_TYPE (outer_type)) == FUNCTION_TYPE
1251 || TREE_CODE (TREE_TYPE (outer_type)) == METHOD_TYPE)
1252 && (TREE_CODE (TREE_TYPE (outer_type))
1253 == TREE_CODE (TREE_TYPE (inner_type)))
1254 && !prototype_p (TREE_TYPE (outer_type))
1255 && useless_type_conversion_p (TREE_TYPE (TREE_TYPE (outer_type)),
1256 TREE_TYPE (TREE_TYPE (inner_type)))))
1260 /* From now on qualifiers on value types do not matter. */
1261 inner_type = TYPE_MAIN_VARIANT (inner_type);
1262 outer_type = TYPE_MAIN_VARIANT (outer_type);
1264 if (inner_type == outer_type)
1267 /* If we know the canonical types, compare them. */
1268 if (TYPE_CANONICAL (inner_type)
1269 && TYPE_CANONICAL (inner_type) == TYPE_CANONICAL (outer_type))
1272 /* Changes in machine mode are never useless conversions unless we
1273 deal with aggregate types in which case we defer to later checks. */
1274 if (TYPE_MODE (inner_type) != TYPE_MODE (outer_type)
1275 && !AGGREGATE_TYPE_P (inner_type))
1278 /* If both the inner and outer types are integral types, then the
1279 conversion is not necessary if they have the same mode and
1280 signedness and precision, and both or neither are boolean. */
1281 if (INTEGRAL_TYPE_P (inner_type)
1282 && INTEGRAL_TYPE_P (outer_type))
1284 /* Preserve changes in signedness or precision. */
1285 if (TYPE_UNSIGNED (inner_type) != TYPE_UNSIGNED (outer_type)
1286 || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
1289 /* We don't need to preserve changes in the types minimum or
1290 maximum value in general as these do not generate code
1291 unless the types precisions are different. */
1295 /* Scalar floating point types with the same mode are compatible. */
1296 else if (SCALAR_FLOAT_TYPE_P (inner_type)
1297 && SCALAR_FLOAT_TYPE_P (outer_type))
1300 /* Fixed point types with the same mode are compatible. */
1301 else if (FIXED_POINT_TYPE_P (inner_type)
1302 && FIXED_POINT_TYPE_P (outer_type))
1305 /* We need to take special care recursing to pointed-to types. */
1306 else if (POINTER_TYPE_P (inner_type)
1307 && POINTER_TYPE_P (outer_type))
1309 /* Do not lose casts to function pointer types. */
1310 if ((TREE_CODE (TREE_TYPE (outer_type)) == FUNCTION_TYPE
1311 || TREE_CODE (TREE_TYPE (outer_type)) == METHOD_TYPE)
1312 && !useless_type_conversion_p (TREE_TYPE (outer_type),
1313 TREE_TYPE (inner_type)))
1316 /* We do not care for const qualification of the pointed-to types
1317 as const qualification has no semantic value to the middle-end. */
1319 /* Otherwise pointers/references are equivalent. */
1323 /* Recurse for complex types. */
1324 else if (TREE_CODE (inner_type) == COMPLEX_TYPE
1325 && TREE_CODE (outer_type) == COMPLEX_TYPE)
1326 return useless_type_conversion_p (TREE_TYPE (outer_type),
1327 TREE_TYPE (inner_type));
1329 /* Recurse for vector types with the same number of subparts. */
1330 else if (TREE_CODE (inner_type) == VECTOR_TYPE
1331 && TREE_CODE (outer_type) == VECTOR_TYPE
1332 && TYPE_PRECISION (inner_type) == TYPE_PRECISION (outer_type))
1333 return useless_type_conversion_p (TREE_TYPE (outer_type),
1334 TREE_TYPE (inner_type));
1336 else if (TREE_CODE (inner_type) == ARRAY_TYPE
1337 && TREE_CODE (outer_type) == ARRAY_TYPE)
1339 /* Preserve string attributes. */
1340 if (TYPE_STRING_FLAG (inner_type) != TYPE_STRING_FLAG (outer_type))
1343 /* Conversions from array types with unknown extent to
1344 array types with known extent are not useless. */
1345 if (!TYPE_DOMAIN (inner_type)
1346 && TYPE_DOMAIN (outer_type))
1349 /* Nor are conversions from array types with non-constant size to
1350 array types with constant size or to different size. */
1351 if (TYPE_SIZE (outer_type)
1352 && TREE_CODE (TYPE_SIZE (outer_type)) == INTEGER_CST
1353 && (!TYPE_SIZE (inner_type)
1354 || TREE_CODE (TYPE_SIZE (inner_type)) != INTEGER_CST
1355 || !tree_int_cst_equal (TYPE_SIZE (outer_type),
1356 TYPE_SIZE (inner_type))))
1359 /* Check conversions between arrays with partially known extents.
1360 If the array min/max values are constant they have to match.
1361 Otherwise allow conversions to unknown and variable extents.
1362 In particular this declares conversions that may change the
1363 mode to BLKmode as useless. */
1364 if (TYPE_DOMAIN (inner_type)
1365 && TYPE_DOMAIN (outer_type)
1366 && TYPE_DOMAIN (inner_type) != TYPE_DOMAIN (outer_type))
1368 tree inner_min = TYPE_MIN_VALUE (TYPE_DOMAIN (inner_type));
1369 tree outer_min = TYPE_MIN_VALUE (TYPE_DOMAIN (outer_type));
1370 tree inner_max = TYPE_MAX_VALUE (TYPE_DOMAIN (inner_type));
1371 tree outer_max = TYPE_MAX_VALUE (TYPE_DOMAIN (outer_type));
1373 /* After gimplification a variable min/max value carries no
1374 additional information compared to a NULL value. All that
1375 matters has been lowered to be part of the IL. */
1376 if (inner_min && TREE_CODE (inner_min) != INTEGER_CST)
1377 inner_min = NULL_TREE;
1378 if (outer_min && TREE_CODE (outer_min) != INTEGER_CST)
1379 outer_min = NULL_TREE;
1380 if (inner_max && TREE_CODE (inner_max) != INTEGER_CST)
1381 inner_max = NULL_TREE;
1382 if (outer_max && TREE_CODE (outer_max) != INTEGER_CST)
1383 outer_max = NULL_TREE;
1385 /* Conversions NULL / variable <- cst are useless, but not
1386 the other way around. */
1389 || !tree_int_cst_equal (inner_min, outer_min)))
1393 || !tree_int_cst_equal (inner_max, outer_max)))
1397 /* Recurse on the element check. */
1398 return useless_type_conversion_p (TREE_TYPE (outer_type),
1399 TREE_TYPE (inner_type));
1402 else if ((TREE_CODE (inner_type) == FUNCTION_TYPE
1403 || TREE_CODE (inner_type) == METHOD_TYPE)
1404 && TREE_CODE (inner_type) == TREE_CODE (outer_type))
1406 tree outer_parm, inner_parm;
1408 /* If the return types are not compatible bail out. */
1409 if (!useless_type_conversion_p (TREE_TYPE (outer_type),
1410 TREE_TYPE (inner_type)))
1413 /* Method types should belong to a compatible base class. */
1414 if (TREE_CODE (inner_type) == METHOD_TYPE
1415 && !useless_type_conversion_p (TYPE_METHOD_BASETYPE (outer_type),
1416 TYPE_METHOD_BASETYPE (inner_type)))
1419 /* A conversion to an unprototyped argument list is ok. */
1420 if (!prototype_p (outer_type))
1423 /* If the unqualified argument types are compatible the conversion
1425 if (TYPE_ARG_TYPES (outer_type) == TYPE_ARG_TYPES (inner_type))
1428 for (outer_parm = TYPE_ARG_TYPES (outer_type),
1429 inner_parm = TYPE_ARG_TYPES (inner_type);
1430 outer_parm && inner_parm;
1431 outer_parm = TREE_CHAIN (outer_parm),
1432 inner_parm = TREE_CHAIN (inner_parm))
1433 if (!useless_type_conversion_p
1434 (TYPE_MAIN_VARIANT (TREE_VALUE (outer_parm)),
1435 TYPE_MAIN_VARIANT (TREE_VALUE (inner_parm))))
1438 /* If there is a mismatch in the number of arguments the functions
1439 are not compatible. */
1440 if (outer_parm || inner_parm)
1443 /* Defer to the target if necessary. */
1444 if (TYPE_ATTRIBUTES (inner_type) || TYPE_ATTRIBUTES (outer_type))
1445 return targetm.comp_type_attributes (outer_type, inner_type) != 0;
1450 /* For aggregates we rely on TYPE_CANONICAL exclusively and require
1451 explicit conversions for types involving to be structurally
1453 else if (AGGREGATE_TYPE_P (inner_type)
1454 && TREE_CODE (inner_type) == TREE_CODE (outer_type))
1460 /* Return true if a conversion from either type of TYPE1 and TYPE2
1461 to the other is not required. Otherwise return false. */
1464 types_compatible_p (tree type1, tree type2)
1466 return (type1 == type2
1467 || (useless_type_conversion_p (type1, type2)
1468 && useless_type_conversion_p (type2, type1)));
1471 /* Return true if EXPR is a useless type conversion, otherwise return
1475 tree_ssa_useless_type_conversion (tree expr)
1477 /* If we have an assignment that merely uses a NOP_EXPR to change
1478 the top of the RHS to the type of the LHS and the type conversion
1479 is "safe", then strip away the type conversion so that we can
1480 enter LHS = RHS into the const_and_copies table. */
1481 if (CONVERT_EXPR_P (expr)
1482 || TREE_CODE (expr) == VIEW_CONVERT_EXPR
1483 || TREE_CODE (expr) == NON_LVALUE_EXPR)
1484 return useless_type_conversion_p
1486 TREE_TYPE (TREE_OPERAND (expr, 0)));
1491 /* Strip conversions from EXP according to
1492 tree_ssa_useless_type_conversion and return the resulting
1496 tree_ssa_strip_useless_type_conversions (tree exp)
1498 while (tree_ssa_useless_type_conversion (exp))
1499 exp = TREE_OPERAND (exp, 0);
1504 /* Internal helper for walk_use_def_chains. VAR, FN and DATA are as
1505 described in walk_use_def_chains.
1507 VISITED is a pointer set used to mark visited SSA_NAMEs to avoid
1508 infinite loops. We used to have a bitmap for this to just mark
1509 SSA versions we had visited. But non-sparse bitmaps are way too
1510 expensive, while sparse bitmaps may cause quadratic behavior.
1512 IS_DFS is true if the caller wants to perform a depth-first search
1513 when visiting PHI nodes. A DFS will visit each PHI argument and
1514 call FN after each one. Otherwise, all the arguments are
1515 visited first and then FN is called with each of the visited
1516 arguments in a separate pass. */
1519 walk_use_def_chains_1 (tree var, walk_use_def_chains_fn fn, void *data,
1520 struct pointer_set_t *visited, bool is_dfs)
1524 if (pointer_set_insert (visited, var))
1527 def_stmt = SSA_NAME_DEF_STMT (var);
1529 if (gimple_code (def_stmt) != GIMPLE_PHI)
1531 /* If we reached the end of the use-def chain, call FN. */
1532 return fn (var, def_stmt, data);
1538 /* When doing a breadth-first search, call FN before following the
1539 use-def links for each argument. */
1541 for (i = 0; i < gimple_phi_num_args (def_stmt); i++)
1542 if (fn (gimple_phi_arg_def (def_stmt, i), def_stmt, data))
1545 /* Follow use-def links out of each PHI argument. */
1546 for (i = 0; i < gimple_phi_num_args (def_stmt); i++)
1548 tree arg = gimple_phi_arg_def (def_stmt, i);
1550 /* ARG may be NULL for newly introduced PHI nodes. */
1552 && TREE_CODE (arg) == SSA_NAME
1553 && walk_use_def_chains_1 (arg, fn, data, visited, is_dfs))
1557 /* When doing a depth-first search, call FN after following the
1558 use-def links for each argument. */
1560 for (i = 0; i < gimple_phi_num_args (def_stmt); i++)
1561 if (fn (gimple_phi_arg_def (def_stmt, i), def_stmt, data))
1570 /* Walk use-def chains starting at the SSA variable VAR. Call
1571 function FN at each reaching definition found. FN takes three
1572 arguments: VAR, its defining statement (DEF_STMT) and a generic
1573 pointer to whatever state information that FN may want to maintain
1574 (DATA). FN is able to stop the walk by returning true, otherwise
1575 in order to continue the walk, FN should return false.
1577 Note, that if DEF_STMT is a PHI node, the semantics are slightly
1578 different. The first argument to FN is no longer the original
1579 variable VAR, but the PHI argument currently being examined. If FN
1580 wants to get at VAR, it should call PHI_RESULT (PHI).
1582 If IS_DFS is true, this function will:
1584 1- walk the use-def chains for all the PHI arguments, and,
1585 2- call (*FN) (ARG, PHI, DATA) on all the PHI arguments.
1587 If IS_DFS is false, the two steps above are done in reverse order
1588 (i.e., a breadth-first search). */
1591 walk_use_def_chains (tree var, walk_use_def_chains_fn fn, void *data,
1596 gcc_assert (TREE_CODE (var) == SSA_NAME);
1598 def_stmt = SSA_NAME_DEF_STMT (var);
1600 /* We only need to recurse if the reaching definition comes from a PHI
1602 if (gimple_code (def_stmt) != GIMPLE_PHI)
1603 (*fn) (var, def_stmt, data);
1606 struct pointer_set_t *visited = pointer_set_create ();
1607 walk_use_def_chains_1 (var, fn, data, visited, is_dfs);
1608 pointer_set_destroy (visited);
1613 /* Emit warnings for uninitialized variables. This is done in two passes.
1615 The first pass notices real uses of SSA names with undefined values.
1616 Such uses are unconditionally uninitialized, and we can be certain that
1617 such a use is a mistake. This pass is run before most optimizations,
1618 so that we catch as many as we can.
1620 The second pass follows PHI nodes to find uses that are potentially
1621 uninitialized. In this case we can't necessarily prove that the use
1622 is really uninitialized. This pass is run after most optimizations,
1623 so that we thread as many jumps and possible, and delete as much dead
1624 code as possible, in order to reduce false positives. We also look
1625 again for plain uninitialized variables, since optimization may have
1626 changed conditionally uninitialized to unconditionally uninitialized. */
1628 /* Emit a warning for T, an SSA_NAME, being uninitialized. The exact
1629 warning text is in MSGID and LOCUS may contain a location or be null. */
1632 warn_uninit (tree t, const char *gmsgid, void *data)
1634 tree var = SSA_NAME_VAR (t);
1635 gimple context = (gimple) data;
1636 location_t location;
1637 expanded_location xloc, floc;
1639 if (!ssa_undefined_value_p (t))
1642 /* TREE_NO_WARNING either means we already warned, or the front end
1643 wishes to suppress the warning. */
1644 if (TREE_NO_WARNING (var))
1647 /* Do not warn if it can be initialized outside this module. */
1648 if (is_global_var (var))
1651 location = (context != NULL && gimple_has_location (context))
1652 ? gimple_location (context)
1653 : DECL_SOURCE_LOCATION (var);
1654 xloc = expand_location (location);
1655 floc = expand_location (DECL_SOURCE_LOCATION (cfun->decl));
1656 if (warning_at (location, OPT_Wuninitialized, gmsgid, var))
1658 TREE_NO_WARNING (var) = 1;
1660 if (location == DECL_SOURCE_LOCATION (var))
1662 if (xloc.file != floc.file
1663 || xloc.line < floc.line
1664 || xloc.line > LOCATION_LINE (cfun->function_end_locus))
1665 inform (DECL_SOURCE_LOCATION (var), "%qD was declared here", var);
1671 bool always_executed;
1672 bool warn_possibly_uninitialized;
1675 /* Called via walk_tree, look for SSA_NAMEs that have empty definitions
1676 and warn about them. */
1679 warn_uninitialized_var (tree *tp, int *walk_subtrees, void *data_)
1681 struct walk_stmt_info *wi = (struct walk_stmt_info *) data_;
1682 struct walk_data *data = (struct walk_data *) wi->info;
1685 /* We do not care about LHS. */
1688 /* Except for operands of dereferences. */
1689 if (!INDIRECT_REF_P (t)
1690 && TREE_CODE (t) != MEM_REF)
1692 t = TREE_OPERAND (t, 0);
1695 switch (TREE_CODE (t))
1698 /* Taking the address of an uninitialized variable does not
1699 count as using it. */
1705 /* A VAR_DECL in the RHS of a gimple statement may mean that
1706 this variable is loaded from memory. */
1710 /* If there is not gimple stmt,
1711 or alias information has not been computed,
1712 then we cannot check VUSE ops. */
1713 if (data->stmt == NULL)
1716 /* If the load happens as part of a call do not warn about it. */
1717 if (is_gimple_call (data->stmt))
1720 vuse = gimple_vuse_op (data->stmt);
1721 if (vuse == NULL_USE_OPERAND_P)
1724 op = USE_FROM_PTR (vuse);
1725 if (t != SSA_NAME_VAR (op)
1726 || !SSA_NAME_IS_DEFAULT_DEF (op))
1728 /* If this is a VUSE of t and it is the default definition,
1729 then warn about op. */
1731 /* Fall through into SSA_NAME. */
1735 /* We only do data flow with SSA_NAMEs, so that's all we
1737 if (data->always_executed)
1738 warn_uninit (t, "%qD is used uninitialized in this function",
1740 else if (data->warn_possibly_uninitialized)
1741 warn_uninit (t, "%qD may be used uninitialized in this function",
1748 /* The total store transformation performed during gimplification
1749 creates uninitialized variable uses. If all is well, these will
1750 be optimized away, so don't warn now. */
1751 if (TREE_CODE (TREE_OPERAND (t, 0)) == SSA_NAME)
1756 if (IS_TYPE_OR_DECL_P (t))
1765 warn_uninitialized_vars (bool warn_possibly_uninitialized)
1767 gimple_stmt_iterator gsi;
1769 struct walk_data data;
1771 data.warn_possibly_uninitialized = warn_possibly_uninitialized;
1776 data.always_executed = dominated_by_p (CDI_POST_DOMINATORS,
1777 single_succ (ENTRY_BLOCK_PTR), bb);
1778 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
1780 struct walk_stmt_info wi;
1781 data.stmt = gsi_stmt (gsi);
1782 if (is_gimple_debug (data.stmt))
1784 memset (&wi, 0, sizeof (wi));
1786 walk_gimple_op (gsi_stmt (gsi), warn_uninitialized_var, &wi);
1794 execute_early_warn_uninitialized (void)
1796 /* Currently, this pass runs always but
1797 execute_late_warn_uninitialized only runs with optimization. With
1798 optimization we want to warn about possible uninitialized as late
1799 as possible, thus don't do it here. However, without
1800 optimization we need to warn here about "may be uninitialized".
1802 calculate_dominance_info (CDI_POST_DOMINATORS);
1804 warn_uninitialized_vars (/*warn_possibly_uninitialized=*/!optimize);
1806 /* Post-dominator information can not be reliably updated. Free it
1809 free_dominance_info (CDI_POST_DOMINATORS);
1814 gate_warn_uninitialized (void)
1816 return warn_uninitialized != 0;
1819 struct gimple_opt_pass pass_early_warn_uninitialized =
1823 "*early_warn_uninitialized", /* name */
1824 gate_warn_uninitialized, /* gate */
1825 execute_early_warn_uninitialized, /* execute */
1828 0, /* static_pass_number */
1829 TV_TREE_UNINIT, /* tv_id */
1830 PROP_ssa, /* properties_required */
1831 0, /* properties_provided */
1832 0, /* properties_destroyed */
1833 0, /* todo_flags_start */
1834 0 /* todo_flags_finish */
1839 /* If necessary, rewrite the base of the reference tree *TP from
1840 a MEM_REF to a plain or converted symbol. */
1843 maybe_rewrite_mem_ref_base (tree *tp)
1847 while (handled_component_p (*tp))
1848 tp = &TREE_OPERAND (*tp, 0);
1849 if (TREE_CODE (*tp) == MEM_REF
1850 && TREE_CODE (TREE_OPERAND (*tp, 0)) == ADDR_EXPR
1851 && integer_zerop (TREE_OPERAND (*tp, 1))
1852 && (sym = TREE_OPERAND (TREE_OPERAND (*tp, 0), 0))
1854 && !TREE_ADDRESSABLE (sym)
1855 && symbol_marked_for_renaming (sym))
1857 if (!useless_type_conversion_p (TREE_TYPE (*tp),
1859 *tp = build1 (VIEW_CONVERT_EXPR,
1860 TREE_TYPE (*tp), sym);
1866 /* For a tree REF return its base if it is the base of a MEM_REF
1867 that cannot be rewritten into SSA form. Otherwise return NULL_TREE. */
1870 non_rewritable_mem_ref_base (tree ref)
1874 /* A plain decl does not need it set. */
1878 while (handled_component_p (base))
1879 base = TREE_OPERAND (base, 0);
1881 /* But watch out for MEM_REFs we cannot lower to a
1882 VIEW_CONVERT_EXPR. */
1883 if (TREE_CODE (base) == MEM_REF
1884 && TREE_CODE (TREE_OPERAND (base, 0)) == ADDR_EXPR)
1886 tree decl = TREE_OPERAND (TREE_OPERAND (base, 0), 0);
1888 && (!integer_zerop (TREE_OPERAND (base, 1))
1889 || (DECL_SIZE (decl)
1890 != TYPE_SIZE (TREE_TYPE (base)))
1891 || TREE_THIS_VOLATILE (decl) != TREE_THIS_VOLATILE (base)))
1898 /* For an lvalue tree LHS return true if it cannot be rewritten into SSA form.
1899 Otherwise return true. */
1902 non_rewritable_lvalue_p (tree lhs)
1904 /* A plain decl is always rewritable. */
1908 /* A decl that is wrapped inside a MEM-REF that covers
1909 it full is also rewritable.
1910 ??? The following could be relaxed allowing component
1911 references that do not change the access size. */
1912 if (TREE_CODE (lhs) == MEM_REF
1913 && TREE_CODE (TREE_OPERAND (lhs, 0)) == ADDR_EXPR
1914 && integer_zerop (TREE_OPERAND (lhs, 1)))
1916 tree decl = TREE_OPERAND (TREE_OPERAND (lhs, 0), 0);
1918 && DECL_SIZE (decl) == TYPE_SIZE (TREE_TYPE (lhs))
1919 && (TREE_THIS_VOLATILE (decl) == TREE_THIS_VOLATILE (lhs)))
1926 /* When possible, clear TREE_ADDRESSABLE bit or set DECL_GIMPLE_REG_P bit and
1927 mark the variable VAR for conversion into SSA. Return true when updating
1928 stmts is required. */
1931 maybe_optimize_var (tree var, bitmap addresses_taken, bitmap not_reg_needs)
1933 bool update_vops = false;
1935 /* Global Variables, result decls cannot be changed. */
1936 if (is_global_var (var)
1937 || TREE_CODE (var) == RESULT_DECL
1938 || bitmap_bit_p (addresses_taken, DECL_UID (var)))
1941 /* If the variable is not in the list of referenced vars then we
1942 do not need to touch it nor can we rename it. */
1943 if (!referenced_var_lookup (cfun, DECL_UID (var)))
1946 if (TREE_ADDRESSABLE (var)
1947 /* Do not change TREE_ADDRESSABLE if we need to preserve var as
1948 a non-register. Otherwise we are confused and forget to
1949 add virtual operands for it. */
1950 && (!is_gimple_reg_type (TREE_TYPE (var))
1951 || !bitmap_bit_p (not_reg_needs, DECL_UID (var))))
1953 TREE_ADDRESSABLE (var) = 0;
1954 if (is_gimple_reg (var))
1955 mark_sym_for_renaming (var);
1959 fprintf (dump_file, "No longer having address taken: ");
1960 print_generic_expr (dump_file, var, 0);
1961 fprintf (dump_file, "\n");
1965 if (!DECL_GIMPLE_REG_P (var)
1966 && !bitmap_bit_p (not_reg_needs, DECL_UID (var))
1967 && (TREE_CODE (TREE_TYPE (var)) == COMPLEX_TYPE
1968 || TREE_CODE (TREE_TYPE (var)) == VECTOR_TYPE)
1969 && !TREE_THIS_VOLATILE (var)
1970 && (TREE_CODE (var) != VAR_DECL || !DECL_HARD_REGISTER (var)))
1972 DECL_GIMPLE_REG_P (var) = 1;
1973 mark_sym_for_renaming (var);
1977 fprintf (dump_file, "Now a gimple register: ");
1978 print_generic_expr (dump_file, var, 0);
1979 fprintf (dump_file, "\n");
1986 /* Compute TREE_ADDRESSABLE and DECL_GIMPLE_REG_P for local variables. */
1989 execute_update_addresses_taken (void)
1991 gimple_stmt_iterator gsi;
1993 bitmap addresses_taken = BITMAP_ALLOC (NULL);
1994 bitmap not_reg_needs = BITMAP_ALLOC (NULL);
1995 bool update_vops = false;
1999 timevar_push (TV_ADDRESS_TAKEN);
2001 /* Collect into ADDRESSES_TAKEN all variables whose address is taken within
2002 the function body. */
2005 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
2007 gimple stmt = gsi_stmt (gsi);
2008 enum gimple_code code = gimple_code (stmt);
2011 /* Note all addresses taken by the stmt. */
2012 gimple_ior_addresses_taken (addresses_taken, stmt);
2014 /* If we have a call or an assignment, see if the lhs contains
2015 a local decl that requires not to be a gimple register. */
2016 if (code == GIMPLE_ASSIGN || code == GIMPLE_CALL)
2018 tree lhs = gimple_get_lhs (stmt);
2020 && TREE_CODE (lhs) != SSA_NAME
2021 && non_rewritable_lvalue_p (lhs))
2023 decl = get_base_address (lhs);
2025 bitmap_set_bit (not_reg_needs, DECL_UID (decl));
2029 if (gimple_assign_single_p (stmt))
2031 tree rhs = gimple_assign_rhs1 (stmt);
2032 if ((decl = non_rewritable_mem_ref_base (rhs)))
2033 bitmap_set_bit (not_reg_needs, DECL_UID (decl));
2036 else if (code == GIMPLE_CALL)
2038 for (i = 0; i < gimple_call_num_args (stmt); ++i)
2040 tree arg = gimple_call_arg (stmt, i);
2041 if ((decl = non_rewritable_mem_ref_base (arg)))
2042 bitmap_set_bit (not_reg_needs, DECL_UID (decl));
2046 else if (code == GIMPLE_ASM)
2048 for (i = 0; i < gimple_asm_noutputs (stmt); ++i)
2050 tree link = gimple_asm_output_op (stmt, i);
2051 tree lhs = TREE_VALUE (link);
2052 if (TREE_CODE (lhs) != SSA_NAME)
2054 decl = get_base_address (lhs);
2056 && (non_rewritable_lvalue_p (lhs)
2057 /* We cannot move required conversions from
2058 the lhs to the rhs in asm statements, so
2059 require we do not need any. */
2060 || !useless_type_conversion_p
2061 (TREE_TYPE (lhs), TREE_TYPE (decl))))
2062 bitmap_set_bit (not_reg_needs, DECL_UID (decl));
2065 for (i = 0; i < gimple_asm_ninputs (stmt); ++i)
2067 tree link = gimple_asm_input_op (stmt, i);
2068 if ((decl = non_rewritable_mem_ref_base (TREE_VALUE (link))))
2069 bitmap_set_bit (not_reg_needs, DECL_UID (decl));
2074 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
2077 gimple phi = gsi_stmt (gsi);
2079 for (i = 0; i < gimple_phi_num_args (phi); i++)
2081 tree op = PHI_ARG_DEF (phi, i), var;
2082 if (TREE_CODE (op) == ADDR_EXPR
2083 && (var = get_base_address (TREE_OPERAND (op, 0))) != NULL
2085 bitmap_set_bit (addresses_taken, DECL_UID (var));
2090 /* We cannot iterate over all referenced vars because that can contain
2091 unused vars from BLOCK trees, which causes code generation differences
2093 for (var = DECL_ARGUMENTS (cfun->decl); var; var = DECL_CHAIN (var))
2094 update_vops |= maybe_optimize_var (var, addresses_taken, not_reg_needs);
2096 FOR_EACH_VEC_ELT (tree, cfun->local_decls, i, var)
2097 update_vops |= maybe_optimize_var (var, addresses_taken, not_reg_needs);
2099 /* Operand caches need to be recomputed for operands referencing the updated
2104 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
2106 gimple stmt = gsi_stmt (gsi);
2108 /* Re-write TARGET_MEM_REFs of symbols we want to
2109 rewrite into SSA form. */
2110 if (gimple_assign_single_p (stmt))
2112 tree lhs = gimple_assign_lhs (stmt);
2113 tree rhs, *rhsp = gimple_assign_rhs1_ptr (stmt);
2116 /* We shouldn't have any fancy wrapping of
2117 component-refs on the LHS, but look through
2118 VIEW_CONVERT_EXPRs as that is easy. */
2119 while (TREE_CODE (lhs) == VIEW_CONVERT_EXPR)
2120 lhs = TREE_OPERAND (lhs, 0);
2121 if (TREE_CODE (lhs) == MEM_REF
2122 && TREE_CODE (TREE_OPERAND (lhs, 0)) == ADDR_EXPR
2123 && integer_zerop (TREE_OPERAND (lhs, 1))
2124 && (sym = TREE_OPERAND (TREE_OPERAND (lhs, 0), 0))
2126 && !TREE_ADDRESSABLE (sym)
2127 && symbol_marked_for_renaming (sym))
2130 lhs = gimple_assign_lhs (stmt);
2132 /* Rewrite the RHS and make sure the resulting assignment
2133 is validly typed. */
2134 maybe_rewrite_mem_ref_base (rhsp);
2135 rhs = gimple_assign_rhs1 (stmt);
2136 if (gimple_assign_lhs (stmt) != lhs
2137 && !useless_type_conversion_p (TREE_TYPE (lhs),
2139 rhs = fold_build1 (VIEW_CONVERT_EXPR,
2140 TREE_TYPE (lhs), rhs);
2142 if (gimple_assign_lhs (stmt) != lhs)
2143 gimple_assign_set_lhs (stmt, lhs);
2145 if (gimple_assign_rhs1 (stmt) != rhs)
2147 gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
2148 gimple_assign_set_rhs_from_tree (&gsi, rhs);
2152 else if (gimple_code (stmt) == GIMPLE_CALL)
2155 for (i = 0; i < gimple_call_num_args (stmt); ++i)
2157 tree *argp = gimple_call_arg_ptr (stmt, i);
2158 maybe_rewrite_mem_ref_base (argp);
2162 else if (gimple_code (stmt) == GIMPLE_ASM)
2165 for (i = 0; i < gimple_asm_noutputs (stmt); ++i)
2167 tree link = gimple_asm_output_op (stmt, i);
2168 maybe_rewrite_mem_ref_base (&TREE_VALUE (link));
2170 for (i = 0; i < gimple_asm_ninputs (stmt); ++i)
2172 tree link = gimple_asm_input_op (stmt, i);
2173 maybe_rewrite_mem_ref_base (&TREE_VALUE (link));
2177 if (gimple_references_memory_p (stmt)
2178 || is_gimple_debug (stmt))
2182 /* Update SSA form here, we are called as non-pass as well. */
2183 update_ssa (TODO_update_ssa);
2186 BITMAP_FREE (not_reg_needs);
2187 BITMAP_FREE (addresses_taken);
2188 timevar_pop (TV_ADDRESS_TAKEN);
2191 struct gimple_opt_pass pass_update_address_taken =
2195 "addressables", /* name */
2200 0, /* static_pass_number */
2201 TV_ADDRESS_TAKEN, /* tv_id */
2202 PROP_ssa, /* properties_required */
2203 0, /* properties_provided */
2204 0, /* properties_destroyed */
2205 0, /* todo_flags_start */
2206 TODO_update_address_taken
2207 | TODO_dump_func /* todo_flags_finish */