Daily bump.
[official-gcc.git] / gcc / vtable-verify.c
blobcb331d2970f3fd02c3602f0b09547a6446816654
1 /* Copyright (C) 2013-2014 Free Software Foundation, Inc.
3 This file is part of GCC.
5 GCC is free software; you can redistribute it and/or modify it under
6 the terms of the GNU General Public License as published by the Free
7 Software Foundation; either version 3, or (at your option) any later
8 version.
10 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
11 WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 for more details.
15 You should have received a copy of the GNU General Public License
16 along with GCC; see the file COPYING3. If not see
17 <http://www.gnu.org/licenses/>. */
19 /* Virtual Table Pointer Security Pass - Detect corruption of vtable pointers
20 before using them for virtual method dispatches. */
22 /* This file is part of the vtable security feature implementation.
23 The vtable security feature is designed to detect when a virtual
24 call is about to be made through an invalid vtable pointer
25 (possibly due to data corruption or malicious attacks). The
26 compiler finds every virtual call, and inserts a verification call
27 before the virtual call. The verification call takes the actual
28 vtable pointer value in the object through which the virtual call
29 is being made, and compares the vtable pointer against a set of all
30 valid vtable pointers that the object could contain (this set is
31 based on the declared type of the object). If the pointer is in
32 the valid set, execution is allowed to continue; otherwise the
33 program is halted.
35 There are several pieces needed in order to make this work: 1. For
36 every virtual class in the program (i.e. a class that contains
37 virtual methods), we need to build the set of all possible valid
38 vtables that an object of that class could point to. This includes
39 vtables for any class(es) that inherit from the class under
40 consideration. 2. For every such data set we build up, we need a
41 way to find and reference the data set. This is complicated by the
42 fact that the real vtable addresses are not known until runtime,
43 when the program is loaded into memory, but we need to reference the
44 sets at compile time when we are inserting verification calls into
45 the program. 3. We need to find every virtual call in the program,
46 and insert the verification call (with the appropriate arguments)
47 before the virtual call. 4. We need some runtime library pieces:
48 the code to build up the data sets at runtime; the code to actually
49 perform the verification using the data sets; and some code to set
50 protections on the data sets, so they themselves do not become
51 hacker targets.
53 To find and reference the set of valid vtable pointers for any given
54 virtual class, we create a special global variable for each virtual
55 class. We refer to this as the "vtable map variable" for that
56 class. The vtable map variable has the type "void *", and is
57 initialized by the compiler to NULL. At runtime when the set of
58 valid vtable pointers for a virtual class, e.g. class Foo, is built,
59 the vtable map variable for class Foo is made to point to the set.
60 During compile time, when the compiler is inserting verification
61 calls into the program, it passes the vtable map variable for the
62 appropriate class to the verification call, so that at runtime the
63 verification call can find the appropriate data set.
65 The actual set of valid vtable pointers for a virtual class,
66 e.g. class Foo, cannot be built until runtime, when the vtables get
67 loaded into memory and their addresses are known. But the knowledge
68 about which vtables belong in which class' hierarchy is only known
69 at compile time. Therefore at compile time we collect class
70 hierarchy and vtable information about every virtual class, and we
71 generate calls to build up the data sets at runtime. To build the
72 data sets, we call one of the functions we add to the runtime
73 library, __VLTRegisterPair. __VLTRegisterPair takes two arguments,
74 a vtable map variable and the address of a vtable. If the vtable
75 map variable is currently NULL, it creates a new data set (hash
76 table), makes the vtable map variable point to the new data set, and
77 inserts the vtable address into the data set. If the vtable map
78 variable is not NULL, it just inserts the vtable address into the
79 data set. In order to make sure that our data sets are built before
80 any verification calls happen, we create a special constructor
81 initialization function for each compilation unit, give it a very
82 high initialization priority, and insert all of our calls to
83 __VLTRegisterPair into our special constructor initialization
84 function.
86 The vtable verification feature is controlled by the flag
87 '-fvtable-verify='. There are three flavors of this:
88 '-fvtable-verify=std', '-fvtable-verify=preinit', and
89 '-fvtable-verify=none'. If the option '-fvtable-verfy=preinit' is
90 used, then our constructor initialization function gets put into the
91 preinit array. This is necessary if there are data sets that need
92 to be built very early in execution. If the constructor
93 initialization function gets put into the preinit array, the we also
94 add calls to __VLTChangePermission at the beginning and end of the
95 function. The call at the beginning sets the permissions on the
96 data sets and vtable map variables to read/write, and the one at the
97 end makes them read-only. If the '-fvtable-verify=std' option is
98 used, the constructor initialization functions are executed at their
99 normal time, and the __VLTChangePermission calls are handled
100 differently (see the comments in libstdc++-v3/libsupc++/vtv_rts.cc).
101 The option '-fvtable-verify=none' turns off vtable verification.
103 This file contains code for the tree pass that goes through all the
104 statements in each basic block, looking for virtual calls, and
105 inserting a call to __VLTVerifyVtablePointer (with appropriate
106 arguments) before each one. It also contains the hash table
107 functions for the data structures used for collecting the class
108 hierarchy data and building/maintaining the vtable map variable data
109 are defined in gcc/vtable-verify.h. These data structures are
110 shared with the code in the C++ front end that collects the class
111 hierarchy & vtable information and generates the vtable map
112 variables (see cp/vtable-class-hierarchy.c). This tree pass should
113 run just before the gimple is converted to RTL.
115 Some implementation details for this pass:
117 To find all of the virtual calls, we iterate through all the
118 gimple statements in each basic block, looking for any call
119 statement with the code "OBJ_TYPE_REF". Once we have found the
120 virtual call, we need to find the vtable pointer through which the
121 call is being made, and the type of the object containing the
122 pointer (to find the appropriate vtable map variable). We then use
123 these to build a call to __VLTVerifyVtablePointer, passing the
124 vtable map variable, and the vtable pointer. We insert the
125 verification call just after the gimple statement that gets the
126 vtable pointer out of the object, and we update the next
127 statement to depend on the result returned from
128 __VLTVerifyVtablePointer (the vtable pointer value), to ensure
129 subsequent compiler phases don't remove or reorder the call (it's no
130 good to have the verification occur after the virtual call, for
131 example). To find the vtable pointer being used (and the type of
132 the object) we search backwards through the def_stmts chain from the
133 virtual call (see verify_bb_vtables for more details). */
135 #include "config.h"
136 #include "system.h"
137 #include "coretypes.h"
138 #include "tree.h"
139 #include "basic-block.h"
140 #include "tree-ssa-alias.h"
141 #include "internal-fn.h"
142 #include "gimple-expr.h"
143 #include "is-a.h"
144 #include "gimple.h"
145 #include "gimple-iterator.h"
146 #include "gimple-ssa.h"
147 #include "tree-phinodes.h"
148 #include "ssa-iterators.h"
149 #include "stringpool.h"
150 #include "tree-ssanames.h"
151 #include "tree-pass.h"
152 #include "cfgloop.h"
154 #include "vtable-verify.h"
156 unsigned num_vtable_map_nodes = 0;
157 int total_num_virtual_calls = 0;
158 int total_num_verified_vcalls = 0;
160 extern GTY(()) tree verify_vtbl_ptr_fndecl;
161 tree verify_vtbl_ptr_fndecl = NULL_TREE;
163 /* Keep track of whether or not any virtual call were verified. */
164 static bool any_verification_calls_generated = false;
166 unsigned int vtable_verify_main (void);
169 /* The following few functions are for the vtbl pointer hash table
170 in the 'registered' field of the struct vtable_map_node. The hash
171 table keeps track of which vtable pointers have been used in
172 calls to __VLTRegisterPair with that particular vtable map variable. */
174 /* This function checks to see if a particular VTABLE_DECL and OFFSET are
175 already in the 'registered' hash table for NODE. */
177 bool
178 vtbl_map_node_registration_find (struct vtbl_map_node *node,
179 tree vtable_decl,
180 unsigned offset)
182 struct vtable_registration key;
183 struct vtable_registration **slot;
185 gcc_assert (node && node->registered);
187 key.vtable_decl = vtable_decl;
188 slot = node->registered->find_slot (&key, NO_INSERT);
190 if (slot && (*slot))
192 unsigned i;
193 for (i = 0; i < ((*slot)->offsets).length (); ++i)
194 if ((*slot)->offsets[i] == offset)
195 return true;
198 return false;
201 /* This function inserts VTABLE_DECL and OFFSET into the 'registered'
202 hash table for NODE. It returns a boolean indicating whether or not
203 it actually inserted anything. */
205 bool
206 vtbl_map_node_registration_insert (struct vtbl_map_node *node,
207 tree vtable_decl,
208 unsigned offset)
210 struct vtable_registration key;
211 struct vtable_registration **slot;
212 bool inserted_something = false;
214 if (!node || !node->registered)
215 return false;
217 key.vtable_decl = vtable_decl;
218 slot = node->registered->find_slot (&key, INSERT);
220 if (! *slot)
222 struct vtable_registration *node;
223 node = XNEW (struct vtable_registration);
224 node->vtable_decl = vtable_decl;
226 (node->offsets).create (10);
227 (node->offsets).safe_push (offset);
228 *slot = node;
229 inserted_something = true;
231 else
233 /* We found the vtable_decl slot; we need to see if it already
234 contains the offset. If not, we need to add the offset. */
235 unsigned i;
236 bool found = false;
237 for (i = 0; i < ((*slot)->offsets).length () && !found; ++i)
238 if ((*slot)->offsets[i] == offset)
239 found = true;
241 if (!found)
243 ((*slot)->offsets).safe_push (offset);
244 inserted_something = true;
247 return inserted_something;
250 /* Hashtable functions for vtable_registration hashtables. */
252 inline hashval_t
253 registration_hasher::hash (const value_type *p)
255 const struct vtable_registration *n = (const struct vtable_registration *) p;
256 return (hashval_t) (DECL_UID (n->vtable_decl));
259 inline bool
260 registration_hasher::equal (const value_type *p1, const compare_type *p2)
262 const struct vtable_registration *n1 =
263 (const struct vtable_registration *) p1;
264 const struct vtable_registration *n2 =
265 (const struct vtable_registration *) p2;
266 return (DECL_UID (n1->vtable_decl) == DECL_UID (n2->vtable_decl));
269 /* End of hashtable functions for "registered" hashtables. */
273 /* Hashtable definition and functions for vtbl_map_hash. */
275 struct vtbl_map_hasher : typed_noop_remove <struct vtbl_map_node>
277 typedef struct vtbl_map_node value_type;
278 typedef struct vtbl_map_node compare_type;
279 static inline hashval_t hash (const value_type *);
280 static inline bool equal (const value_type *, const compare_type *);
283 /* Returns a hash code for P. */
285 inline hashval_t
286 vtbl_map_hasher::hash (const value_type *p)
288 const struct vtbl_map_node n = *((const struct vtbl_map_node *) p);
289 return (hashval_t) IDENTIFIER_HASH_VALUE (n.class_name);
292 /* Returns nonzero if P1 and P2 are equal. */
294 inline bool
295 vtbl_map_hasher::equal (const value_type *p1, const compare_type *p2)
297 const struct vtbl_map_node n1 = *((const struct vtbl_map_node *) p1);
298 const struct vtbl_map_node n2 = *((const struct vtbl_map_node *) p2);
299 return (IDENTIFIER_HASH_VALUE (n1.class_name) ==
300 IDENTIFIER_HASH_VALUE (n2.class_name));
303 /* Here are the two structures into which we insert vtable map nodes.
304 We use two data structures because of the vastly different ways we need
305 to find the nodes for various tasks (see comments in vtable-verify.h
306 for more details. */
308 typedef hash_table<vtbl_map_hasher> vtbl_map_table_type;
309 typedef vtbl_map_table_type::iterator vtbl_map_iterator_type;
311 /* Vtable map variable nodes stored in a hash table. */
312 static vtbl_map_table_type *vtbl_map_hash;
314 /* Vtable map variable nodes stored in a vector. */
315 vec<struct vtbl_map_node *> vtbl_map_nodes_vec;
317 /* Return vtbl_map node for CLASS_NAME without creating a new one. */
319 struct vtbl_map_node *
320 vtbl_map_get_node (tree class_type)
322 struct vtbl_map_node key;
323 struct vtbl_map_node **slot;
325 tree class_type_decl;
326 tree class_name;
327 unsigned int type_quals;
329 if (!vtbl_map_hash)
330 return NULL;
332 gcc_assert (TREE_CODE (class_type) == RECORD_TYPE);
335 /* Find the TYPE_DECL for the class. */
336 class_type_decl = TYPE_NAME (class_type);
338 /* Verify that there aren't any qualifiers on the type. */
339 type_quals = TYPE_QUALS (TREE_TYPE (class_type_decl));
340 gcc_assert (type_quals == TYPE_UNQUALIFIED);
342 /* Get the mangled name for the unqualified type. */
343 gcc_assert (HAS_DECL_ASSEMBLER_NAME_P (class_type_decl));
344 class_name = DECL_ASSEMBLER_NAME (class_type_decl);
346 key.class_name = class_name;
347 slot = (struct vtbl_map_node **) vtbl_map_hash->find_slot (&key, NO_INSERT);
348 if (!slot)
349 return NULL;
350 return *slot;
353 /* Return vtbl_map node assigned to BASE_CLASS_TYPE. Create new one
354 when needed. */
356 struct vtbl_map_node *
357 find_or_create_vtbl_map_node (tree base_class_type)
359 struct vtbl_map_node key;
360 struct vtbl_map_node *node;
361 struct vtbl_map_node **slot;
362 tree class_type_decl;
363 unsigned int type_quals;
365 if (!vtbl_map_hash)
366 vtbl_map_hash = new vtbl_map_table_type (10);
368 /* Find the TYPE_DECL for the class. */
369 class_type_decl = TYPE_NAME (base_class_type);
371 /* Verify that there aren't any type qualifiers on type. */
372 type_quals = TYPE_QUALS (TREE_TYPE (class_type_decl));
373 gcc_assert (type_quals == TYPE_UNQUALIFIED);
375 gcc_assert (HAS_DECL_ASSEMBLER_NAME_P (class_type_decl));
376 key.class_name = DECL_ASSEMBLER_NAME (class_type_decl);
377 slot = (struct vtbl_map_node **) vtbl_map_hash->find_slot (&key, INSERT);
379 if (*slot)
380 return *slot;
382 node = XNEW (struct vtbl_map_node);
383 node->vtbl_map_decl = NULL_TREE;
384 node->class_name = key.class_name;
385 node->uid = num_vtable_map_nodes++;
387 node->class_info = XNEW (struct vtv_graph_node);
388 node->class_info->class_type = base_class_type;
389 node->class_info->class_uid = node->uid;
390 node->class_info->num_processed_children = 0;
392 (node->class_info->parents).create (4);
393 (node->class_info->children).create (4);
395 node->registered = new register_table_type (16);
397 node->is_used = false;
399 vtbl_map_nodes_vec.safe_push (node);
400 gcc_assert (vtbl_map_nodes_vec[node->uid] == node);
402 *slot = node;
403 return node;
406 /* End of hashtable functions for vtable_map variables hash table. */
408 /* Given a gimple STMT, this function checks to see if the statement
409 is an assignment, the rhs of which is getting the vtable pointer
410 value out of an object. (i.e. it's the value we need to verify
411 because its the vtable pointer that will be used for a virtual
412 call). */
414 static bool
415 is_vtable_assignment_stmt (gimple stmt)
418 if (gimple_code (stmt) != GIMPLE_ASSIGN)
419 return false;
420 else
422 tree lhs = gimple_assign_lhs (stmt);
423 tree rhs = gimple_assign_rhs1 (stmt);
425 if (TREE_CODE (lhs) != SSA_NAME)
426 return false;
428 if (TREE_CODE (rhs) != COMPONENT_REF)
429 return false;
431 if (! (TREE_OPERAND (rhs, 1))
432 || (TREE_CODE (TREE_OPERAND (rhs, 1)) != FIELD_DECL))
433 return false;
435 if (! DECL_VIRTUAL_P (TREE_OPERAND (rhs, 1)))
436 return false;
439 return true;
442 /* This function attempts to recover the declared class of an object
443 that is used in making a virtual call. We try to get the type from
444 the type cast in the gimple assignment statement that extracts the
445 vtable pointer from the object (DEF_STMT). The gimple statement
446 usually looks something like this:
448 D.2201_4 = MEM[(struct Event *)this_1(D)]._vptr.Event */
450 static tree
451 extract_object_class_type (tree rhs)
453 tree result = NULL_TREE;
455 /* Try to find and extract the type cast from that stmt. */
456 if (TREE_CODE (rhs) == COMPONENT_REF)
458 tree op0 = TREE_OPERAND (rhs, 0);
459 tree op1 = TREE_OPERAND (rhs, 1);
461 if (TREE_CODE (op1) == FIELD_DECL
462 && DECL_VIRTUAL_P (op1))
464 if (TREE_CODE (op0) == COMPONENT_REF
465 && TREE_CODE (TREE_OPERAND (op0, 0)) == MEM_REF
466 && TREE_CODE (TREE_TYPE (TREE_OPERAND (op0, 0)))== RECORD_TYPE)
467 result = TREE_TYPE (TREE_OPERAND (op0, 0));
468 else
469 result = TREE_TYPE (op0);
471 else if (TREE_CODE (op0) == COMPONENT_REF)
473 result = extract_object_class_type (op0);
474 if (result == NULL_TREE
475 && TREE_CODE (op1) == COMPONENT_REF)
476 result = extract_object_class_type (op1);
480 return result;
483 /* This function traces forward through the def-use chain of an SSA
484 variable to see if it ever gets used in a virtual function call. It
485 returns a boolean indicating whether or not it found a virtual call in
486 the use chain. */
488 static bool
489 var_is_used_for_virtual_call_p (tree lhs, int *mem_ref_depth)
491 imm_use_iterator imm_iter;
492 bool found_vcall = false;
493 use_operand_p use_p;
495 if (TREE_CODE (lhs) != SSA_NAME)
496 return false;
498 if (*mem_ref_depth > 2)
499 return false;
501 /* Iterate through the immediate uses of the current variable. If
502 it's a virtual function call, we're done. Otherwise, if there's
503 an LHS for the use stmt, add the ssa var to the work list
504 (assuming it's not already in the list and is not a variable
505 we've already examined. */
507 FOR_EACH_IMM_USE_FAST (use_p, imm_iter, lhs)
509 gimple stmt2 = USE_STMT (use_p);
511 if (is_gimple_call (stmt2))
513 tree fncall = gimple_call_fn (stmt2);
514 if (fncall && TREE_CODE (fncall) == OBJ_TYPE_REF)
515 found_vcall = true;
516 else
517 return false;
519 else if (gimple_code (stmt2) == GIMPLE_PHI)
521 found_vcall = var_is_used_for_virtual_call_p
522 (gimple_phi_result (stmt2),
523 mem_ref_depth);
525 else if (is_gimple_assign (stmt2))
527 tree rhs = gimple_assign_rhs1 (stmt2);
528 if (TREE_CODE (rhs) == ADDR_EXPR
529 || TREE_CODE (rhs) == MEM_REF)
530 *mem_ref_depth = *mem_ref_depth + 1;
532 if (TREE_CODE (rhs) == COMPONENT_REF)
534 while (TREE_CODE (TREE_OPERAND (rhs, 0)) == COMPONENT_REF)
535 rhs = TREE_OPERAND (rhs, 0);
537 if (TREE_CODE (TREE_OPERAND (rhs, 0)) == ADDR_EXPR
538 || TREE_CODE (TREE_OPERAND (rhs, 0)) == MEM_REF)
539 *mem_ref_depth = *mem_ref_depth + 1;
542 if (*mem_ref_depth < 3)
543 found_vcall = var_is_used_for_virtual_call_p
544 (gimple_assign_lhs (stmt2),
545 mem_ref_depth);
548 else
549 break;
551 if (found_vcall)
552 return true;
555 return false;
558 /* Search through all the statements in a basic block (BB), searching
559 for virtual method calls. For each virtual method dispatch, find
560 the vptr value used, and the statically declared type of the
561 object; retrieve the vtable map variable for the type of the
562 object; generate a call to __VLTVerifyVtablePointer; and insert the
563 generated call into the basic block, after the point where the vptr
564 value is gotten out of the object and before the virtual method
565 dispatch. Make the virtual method dispatch depend on the return
566 value from the verification call, so that subsequent optimizations
567 cannot reorder the two calls. */
569 static void
570 verify_bb_vtables (basic_block bb)
572 gimple_seq stmts;
573 gimple stmt = NULL;
574 gimple_stmt_iterator gsi_vtbl_assign;
575 gimple_stmt_iterator gsi_virtual_call;
577 stmts = bb_seq (bb);
578 gsi_virtual_call = gsi_start (stmts);
579 for (; !gsi_end_p (gsi_virtual_call); gsi_next (&gsi_virtual_call))
581 stmt = gsi_stmt (gsi_virtual_call);
583 /* Count virtual calls. */
584 if (is_gimple_call (stmt))
586 tree fncall = gimple_call_fn (stmt);
587 if (fncall && TREE_CODE (fncall) == OBJ_TYPE_REF)
588 total_num_virtual_calls++;
591 if (is_vtable_assignment_stmt (stmt))
593 tree lhs = gimple_assign_lhs (stmt);
594 tree vtbl_var_decl = NULL_TREE;
595 struct vtbl_map_node *vtable_map_node;
596 tree vtbl_decl = NULL_TREE;
597 gimple call_stmt;
598 const char *vtable_name = "<unknown>";
599 tree tmp0;
600 bool found;
601 int mem_ref_depth = 0;
603 /* Make sure this vptr field access is for a virtual call. */
604 if (!var_is_used_for_virtual_call_p (lhs, &mem_ref_depth))
605 continue;
607 /* Now we have found the virtual method dispatch and
608 the preceding access of the _vptr.* field... Next
609 we need to find the statically declared type of
610 the object, so we can find and use the right
611 vtable map variable in the verification call. */
612 tree class_type = extract_object_class_type
613 (gimple_assign_rhs1 (stmt));
615 gsi_vtbl_assign = gsi_for_stmt (stmt);
617 if (class_type
618 && (TREE_CODE (class_type) == RECORD_TYPE)
619 && TYPE_BINFO (class_type))
621 /* Get the vtable VAR_DECL for the type. */
622 vtbl_var_decl = BINFO_VTABLE (TYPE_BINFO (class_type));
624 if (TREE_CODE (vtbl_var_decl) == POINTER_PLUS_EXPR)
625 vtbl_var_decl = TREE_OPERAND (TREE_OPERAND (vtbl_var_decl, 0),
628 gcc_assert (vtbl_var_decl);
630 vtbl_decl = vtbl_var_decl;
631 vtable_map_node = vtbl_map_get_node
632 (TYPE_MAIN_VARIANT (class_type));
634 gcc_assert (verify_vtbl_ptr_fndecl);
636 /* Given the vtable pointer for the base class of the
637 object, build the call to __VLTVerifyVtablePointer to
638 verify that the object's vtable pointer (contained in
639 lhs) is in the set of valid vtable pointers for the
640 base class. */
642 if (vtable_map_node && vtable_map_node->vtbl_map_decl)
644 vtable_map_node->is_used = true;
645 vtbl_var_decl = vtable_map_node->vtbl_map_decl;
647 if (TREE_CODE (vtbl_decl) == VAR_DECL)
648 vtable_name = IDENTIFIER_POINTER (DECL_NAME (vtbl_decl));
650 /* Call different routines if we are interested in
651 trace information to debug problems. */
652 if (flag_vtv_debug)
654 int len1 = IDENTIFIER_LENGTH
655 (DECL_NAME (vtbl_var_decl));
656 int len2 = strlen (vtable_name);
658 call_stmt = gimple_build_call
659 (verify_vtbl_ptr_fndecl, 4,
660 build1 (ADDR_EXPR,
661 TYPE_POINTER_TO
662 (TREE_TYPE (vtbl_var_decl)),
663 vtbl_var_decl),
664 lhs,
665 build_string_literal
666 (len1 + 1,
667 IDENTIFIER_POINTER
668 (DECL_NAME
669 (vtbl_var_decl))),
670 build_string_literal (len2 + 1,
671 vtable_name));
673 else
674 call_stmt = gimple_build_call
675 (verify_vtbl_ptr_fndecl, 2,
676 build1 (ADDR_EXPR,
677 TYPE_POINTER_TO
678 (TREE_TYPE (vtbl_var_decl)),
679 vtbl_var_decl),
680 lhs);
683 /* Create a new SSA_NAME var to hold the call's
684 return value, and make the call_stmt use the
685 variable for that purpose. */
686 tmp0 = make_temp_ssa_name (TREE_TYPE (lhs), NULL, "VTV");
687 gimple_call_set_lhs (call_stmt, tmp0);
688 update_stmt (call_stmt);
690 /* Replace all uses of lhs with tmp0. */
691 found = false;
692 imm_use_iterator iterator;
693 gimple use_stmt;
694 FOR_EACH_IMM_USE_STMT (use_stmt, iterator, lhs)
696 use_operand_p use_p;
697 if (use_stmt == call_stmt)
698 continue;
699 FOR_EACH_IMM_USE_ON_STMT (use_p, iterator)
700 SET_USE (use_p, tmp0);
701 update_stmt (use_stmt);
702 found = true;
705 gcc_assert (found);
707 /* Insert the new verification call just after the
708 statement that gets the vtable pointer out of the
709 object. */
710 gcc_assert (gsi_stmt (gsi_vtbl_assign) == stmt);
711 gsi_insert_after (&gsi_vtbl_assign, call_stmt,
712 GSI_NEW_STMT);
714 any_verification_calls_generated = true;
715 total_num_verified_vcalls++;
722 /* Definition of this optimization pass. */
724 namespace {
726 const pass_data pass_data_vtable_verify =
728 GIMPLE_PASS, /* type */
729 "vtable-verify", /* name */
730 OPTGROUP_NONE, /* optinfo_flags */
731 TV_VTABLE_VERIFICATION, /* tv_id */
732 ( PROP_cfg | PROP_ssa ), /* properties_required */
733 0, /* properties_provided */
734 0, /* properties_destroyed */
735 0, /* todo_flags_start */
736 TODO_update_ssa, /* todo_flags_finish */
739 class pass_vtable_verify : public gimple_opt_pass
741 public:
742 pass_vtable_verify (gcc::context *ctxt)
743 : gimple_opt_pass (pass_data_vtable_verify, ctxt)
746 /* opt_pass methods: */
747 virtual bool gate (function *) { return (flag_vtable_verify); }
748 virtual unsigned int execute (function *);
750 }; // class pass_vtable_verify
752 /* Loop through all the basic blocks in the current function, passing them to
753 verify_bb_vtables, which searches for virtual calls, and inserts
754 calls to __VLTVerifyVtablePointer. */
756 unsigned int
757 pass_vtable_verify::execute (function *fun)
759 unsigned int ret = 1;
760 basic_block bb;
762 FOR_ALL_BB_FN (bb, fun)
763 verify_bb_vtables (bb);
765 return ret;
768 } // anon namespace
770 gimple_opt_pass *
771 make_pass_vtable_verify (gcc::context *ctxt)
773 return new pass_vtable_verify (ctxt);
776 #include "gt-vtable-verify.h"