gcc/sanopt.c

   1 /* Optimize and expand sanitizer functions.
   2    Copyright (C) 2014-2016 Free Software Foundation, Inc.
   3    Contributed by Marek Polacek <polacek@redhat.com>
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  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/>.  */
  20
  21 #include "config.h"
  22 #include "system.h"
  23 #include "coretypes.h"
  24 #include "backend.h"
  25 #include "tree.h"
  26 #include "gimple.h"
  27 #include "tree-pass.h"
  28 #include "tree-ssa-operands.h"
  29 #include "gimple-pretty-print.h"
  30 #include "fold-const.h"
  31 #include "gimple-iterator.h"
  32 #include "asan.h"
  33 #include "ubsan.h"
  34 #include "params.h"
  35 #include "tree-hash-traits.h"
  36 #include "gimple-ssa.h"
  37 #include "tree-phinodes.h"
  38 #include "ssa-iterators.h"
  39
  40
  41 /* This is used to carry information about basic blocks.  It is
  42    attached to the AUX field of the standard CFG block.  */
  43
  44 struct sanopt_info
  45 {
  46   /* True if this BB might call (directly or indirectly) free/munmap
  47      or similar operation.  */
  48   bool has_freeing_call_p;
  49
  50   /* True if HAS_FREEING_CALL_P flag has been computed.  */
  51   bool has_freeing_call_computed_p;
  52
  53   /* True if there is a block with HAS_FREEING_CALL_P flag set
  54      on any path between an immediate dominator of BB, denoted
  55      imm(BB), and BB.  */
  56   bool imm_dom_path_with_freeing_call_p;
  57
  58   /* True if IMM_DOM_PATH_WITH_FREEING_CALL_P has been computed.  */
  59   bool imm_dom_path_with_freeing_call_computed_p;
  60
  61   /* Number of possibly freeing calls encountered in this bb
  62      (so far).  */
  63   uint64_t freeing_call_events;
  64
  65   /* True if BB is currently being visited during computation
  66      of IMM_DOM_PATH_WITH_FREEING_CALL_P flag.  */
  67   bool being_visited_p;
  68
  69   /* True if this BB has been visited in the dominator walk.  */
  70   bool visited_p;
  71 };
  72
  73 /* If T has a single definition of form T = T2, return T2.  */
  74
  75 static tree
  76 maybe_get_single_definition (tree t)
  77 {
  78   if (TREE_CODE (t) == SSA_NAME)
  79     {
  80       gimple *g = SSA_NAME_DEF_STMT (t);
  81       if (gimple_assign_single_p (g))
  82         return gimple_assign_rhs1 (g);
  83     }
  84   return NULL_TREE;
  85 }
  86
  87 /* Tree triplet for vptr_check_map.  */
  88 struct sanopt_tree_triplet
  89 {
  90   tree t1, t2, t3;
  91 };
  92
  93 /* Traits class for tree triplet hash maps below.  */
  94
  95 struct sanopt_tree_triplet_hash : typed_noop_remove <sanopt_tree_triplet>
  96 {
  97   typedef sanopt_tree_triplet value_type;
  98   typedef sanopt_tree_triplet compare_type;
  99
 100   static inline hashval_t
 101   hash (const sanopt_tree_triplet &ref)
 102   {
 103     inchash::hash hstate (0);
 104     inchash::add_expr (ref.t1, hstate);
 105     inchash::add_expr (ref.t2, hstate);
 106     inchash::add_expr (ref.t3, hstate);
 107     return hstate.end ();
 108   }
 109
 110   static inline bool
 111   equal (const sanopt_tree_triplet &ref1, const sanopt_tree_triplet &ref2)
 112   {
 113     return operand_equal_p (ref1.t1, ref2.t1, 0)
 114            && operand_equal_p (ref1.t2, ref2.t2, 0)
 115            && operand_equal_p (ref1.t3, ref2.t3, 0);
 116   }
 117
 118   static inline void
 119   mark_deleted (sanopt_tree_triplet &ref)
 120   {
 121     ref.t1 = reinterpret_cast<tree> (1);
 122   }
 123
 124   static inline void
 125   mark_empty (sanopt_tree_triplet &ref)
 126   {
 127     ref.t1 = NULL;
 128   }
 129
 130   static inline bool
 131   is_deleted (const sanopt_tree_triplet &ref)
 132   {
 133     return ref.t1 == (void *) 1;
 134   }
 135
 136   static inline bool
 137   is_empty (const sanopt_tree_triplet &ref)
 138   {
 139     return ref.t1 == NULL;
 140   }
 141 };
 142
 143 /* This is used to carry various hash maps and variables used
 144    in sanopt_optimize_walker.  */
 145
 146 struct sanopt_ctx
 147 {
 148   /* This map maps a pointer (the first argument of UBSAN_NULL) to
 149      a vector of UBSAN_NULL call statements that check this pointer.  */
 150   hash_map<tree, auto_vec<gimple *> > null_check_map;
 151
 152   /* This map maps a pointer (the second argument of ASAN_CHECK) to
 153      a vector of ASAN_CHECK call statements that check the access.  */
 154   hash_map<tree_operand_hash, auto_vec<gimple *> > asan_check_map;
 155
 156   /* This map maps a tree triplet (the first, second and fourth argument
 157      of UBSAN_VPTR) to a vector of UBSAN_VPTR call statements that check
 158      that virtual table pointer.  */
 159   hash_map<sanopt_tree_triplet_hash, auto_vec<gimple *> > vptr_check_map;
 160
 161   /* Number of IFN_ASAN_CHECK statements.  */
 162   int asan_num_accesses;
 163 };
 164
 165
 166 /* Return true if there might be any call to free/munmap operation
 167    on any path in between DOM (which should be imm(BB)) and BB.  */
 168
 169 static bool
 170 imm_dom_path_with_freeing_call (basic_block bb, basic_block dom)
 171 {
 172   sanopt_info *info = (sanopt_info *) bb->aux;
 173   edge e;
 174   edge_iterator ei;
 175
 176   if (info->imm_dom_path_with_freeing_call_computed_p)
 177     return info->imm_dom_path_with_freeing_call_p;
 178
 179   info->being_visited_p = true;
 180
 181   FOR_EACH_EDGE (e, ei, bb->preds)
 182     {
 183       sanopt_info *pred_info = (sanopt_info *) e->src->aux;
 184
 185       if (e->src == dom)
 186         continue;
 187
 188       if ((pred_info->imm_dom_path_with_freeing_call_computed_p
 189           && pred_info->imm_dom_path_with_freeing_call_p)
 190           || (pred_info->has_freeing_call_computed_p
 191               && pred_info->has_freeing_call_p))
 192         {
 193           info->imm_dom_path_with_freeing_call_computed_p = true;
 194           info->imm_dom_path_with_freeing_call_p = true;
 195           info->being_visited_p = false;
 196           return true;
 197         }
 198     }
 199
 200   FOR_EACH_EDGE (e, ei, bb->preds)
 201     {
 202       sanopt_info *pred_info = (sanopt_info *) e->src->aux;
 203
 204       if (e->src == dom)
 205         continue;
 206
 207       if (pred_info->has_freeing_call_computed_p)
 208         continue;
 209
 210       gimple_stmt_iterator gsi;
 211       for (gsi = gsi_start_bb (e->src); !gsi_end_p (gsi); gsi_next (&gsi))
 212         {
 213           gimple *stmt = gsi_stmt (gsi);
 214           gasm *asm_stmt;
 215
 216           if ((is_gimple_call (stmt) && !nonfreeing_call_p (stmt))
 217               || ((asm_stmt = dyn_cast <gasm *> (stmt))
 218                   && (gimple_asm_clobbers_memory_p (asm_stmt)
 219                       || gimple_asm_volatile_p (asm_stmt))))
 220             {
 221               pred_info->has_freeing_call_p = true;
 222               break;
 223             }
 224         }
 225
 226       pred_info->has_freeing_call_computed_p = true;
 227       if (pred_info->has_freeing_call_p)
 228         {
 229           info->imm_dom_path_with_freeing_call_computed_p = true;
 230           info->imm_dom_path_with_freeing_call_p = true;
 231           info->being_visited_p = false;
 232           return true;
 233         }
 234     }
 235
 236   FOR_EACH_EDGE (e, ei, bb->preds)
 237     {
 238       if (e->src == dom)
 239         continue;
 240
 241       basic_block src;
 242       for (src = e->src; src != dom; )
 243         {
 244           sanopt_info *pred_info = (sanopt_info *) src->aux;
 245           if (pred_info->being_visited_p)
 246             break;
 247           basic_block imm = get_immediate_dominator (CDI_DOMINATORS, src);
 248           if (imm_dom_path_with_freeing_call (src, imm))
 249             {
 250               info->imm_dom_path_with_freeing_call_computed_p = true;
 251               info->imm_dom_path_with_freeing_call_p = true;
 252               info->being_visited_p = false;
 253               return true;
 254             }
 255           src = imm;
 256         }
 257     }
 258
 259   info->imm_dom_path_with_freeing_call_computed_p = true;
 260   info->imm_dom_path_with_freeing_call_p = false;
 261   info->being_visited_p = false;
 262   return false;
 263 }
 264
 265 /* Get the first dominating check from the list of stored checks.
 266    Non-dominating checks are silently dropped.  */
 267
 268 static gimple *
 269 maybe_get_dominating_check (auto_vec<gimple *> &v)
 270 {
 271   for (; !v.is_empty (); v.pop ())
 272     {
 273       gimple *g = v.last ();
 274       sanopt_info *si = (sanopt_info *) gimple_bb (g)->aux;
 275       if (!si->visited_p)
 276         /* At this point we shouldn't have any statements
 277            that aren't dominating the current BB.  */
 278         return g;
 279     }
 280   return NULL;
 281 }
 282
 283 /* Optimize away redundant UBSAN_NULL calls.  */
 284
 285 static bool
 286 maybe_optimize_ubsan_null_ifn (struct sanopt_ctx *ctx, gimple *stmt)
 287 {
 288   gcc_assert (gimple_call_num_args (stmt) == 3);
 289   tree ptr = gimple_call_arg (stmt, 0);
 290   tree cur_align = gimple_call_arg (stmt, 2);
 291   gcc_assert (TREE_CODE (cur_align) == INTEGER_CST);
 292   bool remove = false;
 293
 294   auto_vec<gimple *> &v = ctx->null_check_map.get_or_insert (ptr);
 295   gimple *g = maybe_get_dominating_check (v);
 296   if (!g)
 297     {
 298       /* For this PTR we don't have any UBSAN_NULL stmts recorded, so there's
 299          nothing to optimize yet.  */
 300       v.safe_push (stmt);
 301       return false;
 302     }
 303
 304   /* We already have recorded a UBSAN_NULL check for this pointer. Perhaps we
 305      can drop this one.  But only if this check doesn't specify stricter
 306      alignment.  */
 307
 308   tree align = gimple_call_arg (g, 2);
 309   int kind = tree_to_shwi (gimple_call_arg (g, 1));
 310   /* If this is a NULL pointer check where we had segv anyway, we can
 311      remove it.  */
 312   if (integer_zerop (align)
 313       && (kind == UBSAN_LOAD_OF
 314           || kind == UBSAN_STORE_OF
 315           || kind == UBSAN_MEMBER_ACCESS))
 316     remove = true;
 317   /* Otherwise remove the check in non-recovering mode, or if the
 318      stmts have same location.  */
 319   else if (integer_zerop (align))
 320     remove = (flag_sanitize_recover & SANITIZE_NULL) == 0
 321               || flag_sanitize_undefined_trap_on_error
 322               || gimple_location (g) == gimple_location (stmt);
 323   else if (tree_int_cst_le (cur_align, align))
 324     remove = (flag_sanitize_recover & SANITIZE_ALIGNMENT) == 0
 325               || flag_sanitize_undefined_trap_on_error
 326               || gimple_location (g) == gimple_location (stmt);
 327
 328   if (!remove && gimple_bb (g) == gimple_bb (stmt)
 329       && tree_int_cst_compare (cur_align, align) == 0)
 330     v.pop ();
 331
 332   if (!remove)
 333     v.safe_push (stmt);
 334   return remove;
 335 }
 336
 337 /* Optimize away redundant UBSAN_VPTR calls.  The second argument
 338    is the value loaded from the virtual table, so rely on FRE to find out
 339    when we can actually optimize.  */
 340
 341 static bool
 342 maybe_optimize_ubsan_vptr_ifn (struct sanopt_ctx *ctx, gimple *stmt)
 343 {
 344   gcc_assert (gimple_call_num_args (stmt) == 5);
 345   sanopt_tree_triplet triplet;
 346   triplet.t1 = gimple_call_arg (stmt, 0);
 347   triplet.t2 = gimple_call_arg (stmt, 1);
 348   triplet.t3 = gimple_call_arg (stmt, 3);
 349
 350   auto_vec<gimple *> &v = ctx->vptr_check_map.get_or_insert (triplet);
 351   gimple *g = maybe_get_dominating_check (v);
 352   if (!g)
 353     {
 354       /* For this PTR we don't have any UBSAN_VPTR stmts recorded, so there's
 355          nothing to optimize yet.  */
 356       v.safe_push (stmt);
 357       return false;
 358     }
 359
 360   return true;
 361 }
 362
 363 /* Returns TRUE if ASan check of length LEN in block BB can be removed
 364    if preceded by checks in V.  */
 365
 366 static bool
 367 can_remove_asan_check (auto_vec<gimple *> &v, tree len, basic_block bb)
 368 {
 369   unsigned int i;
 370   gimple *g;
 371   gimple *to_pop = NULL;
 372   bool remove = false;
 373   basic_block last_bb = bb;
 374   bool cleanup = false;
 375
 376   FOR_EACH_VEC_ELT_REVERSE (v, i, g)
 377     {
 378       basic_block gbb = gimple_bb (g);
 379       sanopt_info *si = (sanopt_info *) gbb->aux;
 380       if (gimple_uid (g) < si->freeing_call_events)
 381         {
 382           /* If there is a potentially freeing call after g in gbb, we should
 383              remove it from the vector, can't use in optimization.  */
 384           cleanup = true;
 385           continue;
 386         }
 387
 388       tree glen = gimple_call_arg (g, 2);
 389       gcc_assert (TREE_CODE (glen) == INTEGER_CST);
 390
 391       /* If we've checked only smaller length than we want to check now,
 392          we can't remove the current stmt.  If g is in the same basic block,
 393          we want to remove it though, as the current stmt is better.  */
 394       if (tree_int_cst_lt (glen, len))
 395         {
 396           if (gbb == bb)
 397             {
 398               to_pop = g;
 399               cleanup = true;
 400             }
 401           continue;
 402         }
 403
 404       while (last_bb != gbb)
 405         {
 406           /* Paths from last_bb to bb have been checked before.
 407              gbb is necessarily a dominator of last_bb, but not necessarily
 408              immediate dominator.  */
 409           if (((sanopt_info *) last_bb->aux)->freeing_call_events)
 410             break;
 411
 412           basic_block imm = get_immediate_dominator (CDI_DOMINATORS, last_bb);
 413           gcc_assert (imm);
 414           if (imm_dom_path_with_freeing_call (last_bb, imm))
 415             break;
 416
 417           last_bb = imm;
 418         }
 419       if (last_bb == gbb)
 420         remove = true;
 421       break;
 422     }
 423
 424   if (cleanup)
 425     {
 426       unsigned int j = 0, l = v.length ();
 427       for (i = 0; i < l; i++)
 428         if (v[i] != to_pop
 429             && (gimple_uid (v[i])
 430                 == ((sanopt_info *)
 431                     gimple_bb (v[i])->aux)->freeing_call_events))
 432           {
 433             if (i != j)
 434               v[j] = v[i];
 435             j++;
 436           }
 437       v.truncate (j);
 438     }
 439
 440   return remove;
 441 }
 442
 443 /* Optimize away redundant ASAN_CHECK calls.  */
 444
 445 static bool
 446 maybe_optimize_asan_check_ifn (struct sanopt_ctx *ctx, gimple *stmt)
 447 {
 448   gcc_assert (gimple_call_num_args (stmt) == 4);
 449   tree ptr = gimple_call_arg (stmt, 1);
 450   tree len = gimple_call_arg (stmt, 2);
 451   basic_block bb = gimple_bb (stmt);
 452   sanopt_info *info = (sanopt_info *) bb->aux;
 453
 454   if (TREE_CODE (len) != INTEGER_CST)
 455     return false;
 456   if (integer_zerop (len))
 457     return false;
 458
 459   gimple_set_uid (stmt, info->freeing_call_events);
 460
 461   auto_vec<gimple *> *ptr_checks = &ctx->asan_check_map.get_or_insert (ptr);
 462
 463   tree base_addr = maybe_get_single_definition (ptr);
 464   auto_vec<gimple *> *base_checks = NULL;
 465   if (base_addr)
 466     {
 467       base_checks = &ctx->asan_check_map.get_or_insert (base_addr);
 468       /* Original pointer might have been invalidated.  */
 469       ptr_checks = ctx->asan_check_map.get (ptr);
 470     }
 471
 472   gimple *g = maybe_get_dominating_check (*ptr_checks);
 473   gimple *g2 = NULL;
 474
 475   if (base_checks)
 476     /* Try with base address as well.  */
 477     g2 = maybe_get_dominating_check (*base_checks);
 478
 479   if (g == NULL && g2 == NULL)
 480     {
 481       /* For this PTR we don't have any ASAN_CHECK stmts recorded, so there's
 482          nothing to optimize yet.  */
 483       ptr_checks->safe_push (stmt);
 484       if (base_checks)
 485         base_checks->safe_push (stmt);
 486       return false;
 487     }
 488
 489   bool remove = false;
 490
 491   if (ptr_checks)
 492     remove = can_remove_asan_check (*ptr_checks, len, bb);
 493
 494   if (!remove && base_checks)
 495     /* Try with base address as well.  */
 496     remove = can_remove_asan_check (*base_checks, len, bb);
 497
 498   if (!remove)
 499     {
 500       ptr_checks->safe_push (stmt);
 501       if (base_checks)
 502         base_checks->safe_push (stmt);
 503     }
 504
 505   return remove;
 506 }
 507
 508 /* Try to optimize away redundant UBSAN_NULL and ASAN_CHECK calls.
 509
 510    We walk blocks in the CFG via a depth first search of the dominator
 511    tree; we push unique UBSAN_NULL or ASAN_CHECK statements into a vector
 512    in the NULL_CHECK_MAP or ASAN_CHECK_MAP hash maps as we enter the
 513    blocks.  When leaving a block, we mark the block as visited; then
 514    when checking the statements in the vector, we ignore statements that
 515    are coming from already visited blocks, because these cannot dominate
 516    anything anymore.  CTX is a sanopt context.  */
 517
 518 static void
 519 sanopt_optimize_walker (basic_block bb, struct sanopt_ctx *ctx)
 520 {
 521   basic_block son;
 522   gimple_stmt_iterator gsi;
 523   sanopt_info *info = (sanopt_info *) bb->aux;
 524   bool asan_check_optimize = (flag_sanitize & SANITIZE_ADDRESS) != 0;
 525
 526   for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi);)
 527     {
 528       gimple *stmt = gsi_stmt (gsi);
 529       bool remove = false;
 530
 531       if (!is_gimple_call (stmt))
 532         {
 533           /* Handle asm volatile or asm with "memory" clobber
 534              the same as potentionally freeing call.  */
 535           gasm *asm_stmt = dyn_cast <gasm *> (stmt);
 536           if (asm_stmt
 537               && asan_check_optimize
 538               && (gimple_asm_clobbers_memory_p (asm_stmt)
 539                   || gimple_asm_volatile_p (asm_stmt)))
 540             info->freeing_call_events++;
 541           gsi_next (&gsi);
 542           continue;
 543         }
 544
 545       if (asan_check_optimize && !nonfreeing_call_p (stmt))
 546         info->freeing_call_events++;
 547
 548       /* If __asan_before_dynamic_init ("module"); is followed by
 549          __asan_after_dynamic_init (); without intervening memory loads/stores,
 550          there is nothing to guard, so optimize both away.  */
 551       if (asan_check_optimize
 552           && gimple_call_builtin_p (stmt, BUILT_IN_ASAN_BEFORE_DYNAMIC_INIT))
 553         {
 554           use_operand_p use;
 555           gimple *use_stmt;
 556           if (single_imm_use (gimple_vdef (stmt), &use, &use_stmt))
 557             {
 558               if (is_gimple_call (use_stmt)
 559                   && gimple_call_builtin_p (use_stmt,
 560                                             BUILT_IN_ASAN_AFTER_DYNAMIC_INIT))
 561                 {
 562                   unlink_stmt_vdef (use_stmt);
 563                   gimple_stmt_iterator gsi2 = gsi_for_stmt (use_stmt);
 564                   gsi_remove (&gsi2, true);
 565                   remove = true;
 566                 }
 567             }
 568         }
 569
 570       if (gimple_call_internal_p (stmt))
 571         switch (gimple_call_internal_fn (stmt))
 572           {
 573           case IFN_UBSAN_NULL:
 574             remove = maybe_optimize_ubsan_null_ifn (ctx, stmt);
 575             break;
 576           case IFN_UBSAN_VPTR:
 577             remove = maybe_optimize_ubsan_vptr_ifn (ctx, stmt);
 578             break;
 579           case IFN_ASAN_CHECK:
 580             if (asan_check_optimize)
 581               remove = maybe_optimize_asan_check_ifn (ctx, stmt);
 582             if (!remove)
 583               ctx->asan_num_accesses++;
 584             break;
 585           default:
 586             break;
 587           }
 588
 589       if (remove)
 590         {
 591           /* Drop this check.  */
 592           if (dump_file && (dump_flags & TDF_DETAILS))
 593             {
 594               fprintf (dump_file, "Optimizing out\n  ");
 595               print_gimple_stmt (dump_file, stmt, 0, dump_flags);
 596               fprintf (dump_file, "\n");
 597             }
 598           unlink_stmt_vdef (stmt);
 599           gsi_remove (&gsi, true);
 600         }
 601       else
 602         gsi_next (&gsi);
 603     }
 604
 605   if (asan_check_optimize)
 606     {
 607       info->has_freeing_call_p = info->freeing_call_events != 0;
 608       info->has_freeing_call_computed_p = true;
 609     }
 610
 611   for (son = first_dom_son (CDI_DOMINATORS, bb);
 612        son;
 613        son = next_dom_son (CDI_DOMINATORS, son))
 614     sanopt_optimize_walker (son, ctx);
 615
 616   /* We're leaving this BB, so mark it to that effect.  */
 617   info->visited_p = true;
 618 }
 619
 620 /* Try to remove redundant sanitizer checks in function FUN.  */
 621
 622 static int
 623 sanopt_optimize (function *fun)
 624 {
 625   struct sanopt_ctx ctx;
 626   ctx.asan_num_accesses = 0;
 627
 628   /* Set up block info for each basic block.  */
 629   alloc_aux_for_blocks (sizeof (sanopt_info));
 630
 631   /* We're going to do a dominator walk, so ensure that we have
 632      dominance information.  */
 633   calculate_dominance_info (CDI_DOMINATORS);
 634
 635   /* Recursively walk the dominator tree optimizing away
 636      redundant checks.  */
 637   sanopt_optimize_walker (ENTRY_BLOCK_PTR_FOR_FN (fun), &ctx);
 638
 639   free_aux_for_blocks ();
 640
 641   return ctx.asan_num_accesses;
 642 }
 643
 644 /* Perform optimization of sanitize functions.  */
 645
 646 namespace {
 647
 648 const pass_data pass_data_sanopt =
 649 {
 650   GIMPLE_PASS, /* type */
 651   "sanopt", /* name */
 652   OPTGROUP_NONE, /* optinfo_flags */
 653   TV_NONE, /* tv_id */
 654   ( PROP_ssa | PROP_cfg | PROP_gimple_leh ), /* properties_required */
 655   0, /* properties_provided */
 656   0, /* properties_destroyed */
 657   0, /* todo_flags_start */
 658   TODO_update_ssa, /* todo_flags_finish */
 659 };
 660
 661 class pass_sanopt : public gimple_opt_pass
 662 {
 663 public:
 664   pass_sanopt (gcc::context *ctxt)
 665     : gimple_opt_pass (pass_data_sanopt, ctxt)
 666   {}
 667
 668   /* opt_pass methods: */
 669   virtual bool gate (function *) { return flag_sanitize; }
 670   virtual unsigned int execute (function *);
 671
 672 }; // class pass_sanopt
 673
 674 unsigned int
 675 pass_sanopt::execute (function *fun)
 676 {
 677   basic_block bb;
 678   int asan_num_accesses = 0;
 679
 680   /* Try to remove redundant checks.  */
 681   if (optimize
 682       && (flag_sanitize
 683           & (SANITIZE_NULL | SANITIZE_ALIGNMENT
 684              | SANITIZE_ADDRESS | SANITIZE_VPTR)))
 685     asan_num_accesses = sanopt_optimize (fun);
 686   else if (flag_sanitize & SANITIZE_ADDRESS)
 687     {
 688       gimple_stmt_iterator gsi;
 689       FOR_EACH_BB_FN (bb, fun)
 690         for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
 691           {
 692             gimple *stmt = gsi_stmt (gsi);
 693             if (gimple_call_internal_p (stmt, IFN_ASAN_CHECK))
 694               ++asan_num_accesses;
 695           }
 696     }
 697
 698   bool use_calls = ASAN_INSTRUMENTATION_WITH_CALL_THRESHOLD < INT_MAX
 699     && asan_num_accesses >= ASAN_INSTRUMENTATION_WITH_CALL_THRESHOLD;
 700
 701   FOR_EACH_BB_FN (bb, fun)
 702     {
 703       gimple_stmt_iterator gsi;
 704       for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); )
 705         {
 706           gimple *stmt = gsi_stmt (gsi);
 707           bool no_next = false;
 708
 709           if (!is_gimple_call (stmt))
 710             {
 711               gsi_next (&gsi);
 712               continue;
 713             }
 714
 715           if (gimple_call_internal_p (stmt))
 716             {
 717               enum internal_fn ifn = gimple_call_internal_fn (stmt);
 718               switch (ifn)
 719                 {
 720                 case IFN_UBSAN_NULL:
 721                   no_next = ubsan_expand_null_ifn (&gsi);
 722                   break;
 723                 case IFN_UBSAN_BOUNDS:
 724                   no_next = ubsan_expand_bounds_ifn (&gsi);
 725                   break;
 726                 case IFN_UBSAN_OBJECT_SIZE:
 727                   no_next = ubsan_expand_objsize_ifn (&gsi);
 728                   break;
 729                 case IFN_UBSAN_VPTR:
 730                   no_next = ubsan_expand_vptr_ifn (&gsi);
 731                   break;
 732                 case IFN_ASAN_CHECK:
 733                   no_next = asan_expand_check_ifn (&gsi, use_calls);
 734                   break;
 735                 case IFN_ASAN_MARK:
 736                   no_next = asan_expand_mark_ifn (&gsi);
 737                   break;
 738                 default:
 739                   break;
 740                 }
 741             }
 742           else if (gimple_call_builtin_p (stmt, BUILT_IN_NORMAL))
 743             {
 744               tree callee = gimple_call_fndecl (stmt);
 745               switch (DECL_FUNCTION_CODE (callee))
 746                 {
 747                 case BUILT_IN_UNREACHABLE:
 748                   if (flag_sanitize & SANITIZE_UNREACHABLE
 749                       && !lookup_attribute ("no_sanitize_undefined",
 750                                             DECL_ATTRIBUTES (fun->decl)))
 751                     no_next = ubsan_instrument_unreachable (&gsi);
 752                   break;
 753                 default:
 754                   break;
 755                 }
 756             }
 757
 758           if (dump_file && (dump_flags & TDF_DETAILS))
 759             {
 760               fprintf (dump_file, "Expanded\n  ");
 761               print_gimple_stmt (dump_file, stmt, 0, dump_flags);
 762               fprintf (dump_file, "\n");
 763             }
 764
 765           if (!no_next)
 766             gsi_next (&gsi);
 767         }
 768     }
 769   return 0;
 770 }
 771
 772 } // anon namespace
 773
 774 gimple_opt_pass *
 775 make_pass_sanopt (gcc::context *ctxt)
 776 {
 777   return new pass_sanopt (ctxt);
 778 }