Merge trunk version 193672 into gupc branch.

[official-gcc.git] / gcc / asan.c

/* AddressSanitizer, a fast memory error detector.
   Copyright (C) 2012 Free Software Foundation, Inc.
   Contributed by Kostya Serebryany <kcc@google.com>

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */


#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "gimple.h"
#include "tree-iterator.h"
#include "tree-flow.h"
#include "tree-pass.h"
#include "asan.h"
#include "gimple-pretty-print.h"
#include "target.h"
#include "expr.h"
#include "optabs.h"
#include "output.h"
#include "tm_p.h"

/* AddressSanitizer finds out-of-bounds and use-after-free bugs
   with <2x slowdown on average.

   The tool consists of two parts:
   instrumentation module (this file) and a run-time library.
   The instrumentation module adds a run-time check before every memory insn.
     For a 8- or 16- byte load accessing address X:
       ShadowAddr = (X >> 3) + Offset
       ShadowValue = *(char*)ShadowAddr;  // *(short*) for 16-byte access.
       if (ShadowValue)
         __asan_report_load8(X);
     For a load of N bytes (N=1, 2 or 4) from address X:
       ShadowAddr = (X >> 3) + Offset
       ShadowValue = *(char*)ShadowAddr;
       if (ShadowValue)
         if ((X & 7) + N - 1 > ShadowValue)
           __asan_report_loadN(X);
   Stores are instrumented similarly, but using __asan_report_storeN functions.
   A call too __asan_init() is inserted to the list of module CTORs.

   The run-time library redefines malloc (so that redzone are inserted around
   the allocated memory) and free (so that reuse of free-ed memory is delayed),
   provides __asan_report* and __asan_init functions.

   Read more:
   http://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm

   The current implementation supports detection of out-of-bounds and
   use-after-free in the heap, on the stack and for global variables.

   [Protection of stack variables]

   To understand how detection of out-of-bounds and use-after-free works
   for stack variables, lets look at this example on x86_64 where the
   stack grows downward:

     int
     foo ()
     {
       char a[23] = {0};
       int b[2] = {0};

       a[5] = 1;
       b[1] = 2;

       return a[5] + b[1];
     }

   For this function, the stack protected by asan will be organized as
   follows, from the top of the stack to the bottom:

   Slot 1/ [red zone of 32 bytes called 'RIGHT RedZone']

   Slot 2/ [8 bytes of red zone, that adds up to the space of 'a' to make
           the next slot be 32 bytes aligned; this one is called Partial
           Redzone; this 32 bytes alignment is an asan constraint]

   Slot 3/ [24 bytes for variable 'a']

   Slot 4/ [red zone of 32 bytes called 'Middle RedZone']

   Slot 5/ [24 bytes of Partial Red Zone (similar to slot 2]

   Slot 6/ [8 bytes for variable 'b']

   Slot 7/ [32 bytes of Red Zone at the bottom of the stack, called
            'LEFT RedZone']

   The 32 bytes of LEFT red zone at the bottom of the stack can be
   decomposed as such:

     1/ The first 8 bytes contain a magical asan number that is always
     0x41B58AB3.

     2/ The following 8 bytes contains a pointer to a string (to be
     parsed at runtime by the runtime asan library), which format is
     the following:

      "<function-name> <space> <num-of-variables-on-the-stack>
      (<32-bytes-aligned-offset-in-bytes-of-variable> <space>
      <length-of-var-in-bytes> ){n} "

        where '(...){n}' means the content inside the parenthesis occurs 'n'
        times, with 'n' being the number of variables on the stack.

      3/ The following 16 bytes of the red zone have no particular
      format.

   The shadow memory for that stack layout is going to look like this:

     - content of shadow memory 8 bytes for slot 7: 0xF1F1F1F1.
       The F1 byte pattern is a magic number called
       ASAN_STACK_MAGIC_LEFT and is a way for the runtime to know that
       the memory for that shadow byte is part of a the LEFT red zone
       intended to seat at the bottom of the variables on the stack.

     - content of shadow memory 8 bytes for slots 6 and 5:
       0xF4F4F400.  The F4 byte pattern is a magic number
       called ASAN_STACK_MAGIC_PARTIAL.  It flags the fact that the
       memory region for this shadow byte is a PARTIAL red zone
       intended to pad a variable A, so that the slot following
       {A,padding} is 32 bytes aligned.

       Note that the fact that the least significant byte of this
       shadow memory content is 00 means that 8 bytes of its
       corresponding memory (which corresponds to the memory of
       variable 'b') is addressable.

     - content of shadow memory 8 bytes for slot 4: 0xF2F2F2F2.
       The F2 byte pattern is a magic number called
       ASAN_STACK_MAGIC_MIDDLE.  It flags the fact that the memory
       region for this shadow byte is a MIDDLE red zone intended to
       seat between two 32 aligned slots of {variable,padding}.

     - content of shadow memory 8 bytes for slot 3 and 2:
       0xF4000000.  This represents is the concatenation of
       variable 'a' and the partial red zone following it, like what we
       had for variable 'b'.  The least significant 3 bytes being 00
       means that the 3 bytes of variable 'a' are addressable.

     - content of shadow memory 8 bytes for slot 1: 0xF3F3F3F3.
       The F3 byte pattern is a magic number called
       ASAN_STACK_MAGIC_RIGHT.  It flags the fact that the memory
       region for this shadow byte is a RIGHT red zone intended to seat
       at the top of the variables of the stack.

   Note that the real variable layout is done in expand_used_vars in
   cfgexpand.c.  As far as Address Sanitizer is concerned, it lays out
   stack variables as well as the different red zones, emits some
   prologue code to populate the shadow memory as to poison (mark as
   non-accessible) the regions of the red zones and mark the regions of
   stack variables as accessible, and emit some epilogue code to
   un-poison (mark as accessible) the regions of red zones right before
   the function exits.

   [Protection of global variables]

   The basic idea is to insert a red zone between two global variables
   and install a constructor function that calls the asan runtime to do
   the populating of the relevant shadow memory regions at load time.

   So the global variables are laid out as to insert a red zone between
   them. The size of the red zones is so that each variable starts on a
   32 bytes boundary.

   Then a constructor function is installed so that, for each global
   variable, it calls the runtime asan library function
   __asan_register_globals_with an instance of this type:

     struct __asan_global
     {
       // Address of the beginning of the global variable.
       const void *__beg;

       // Initial size of the global variable.
       uptr __size;

       // Size of the global variable + size of the red zone.  This
       //   size is 32 bytes aligned.
       uptr __size_with_redzone;

       // Name of the global variable.
       const void *__name;

       // This is always set to NULL for now.
       uptr __has_dynamic_init;
     }

   A destructor function that calls the runtime asan library function
   _asan_unregister_globals is also installed.  */

alias_set_type asan_shadow_set = -1;

/* Pointer types to 1 resp. 2 byte integers in shadow memory.  A separate
   alias set is used for all shadow memory accesses.  */
static GTY(()) tree shadow_ptr_types[2];

/* Asan pretty-printer, used for buidling of the description STRING_CSTs.  */
static pretty_printer asan_pp;
static bool asan_pp_initialized;

/* Initialize asan_pp.  */

static void
asan_pp_initialize (void)
{
  pp_construct (&asan_pp, /* prefix */NULL, /* line-width */0);
  asan_pp_initialized = true;
}

/* Create ADDR_EXPR of STRING_CST with asan_pp text.  */

static tree
asan_pp_string (void)
{
  const char *buf = pp_base_formatted_text (&asan_pp);
  size_t len = strlen (buf);
  tree ret = build_string (len + 1, buf);
  TREE_TYPE (ret)
    = build_array_type (char_type_node, build_index_type (size_int (len)));
  TREE_READONLY (ret) = 1;
  TREE_STATIC (ret) = 1;
  return build1 (ADDR_EXPR, build_pointer_type (char_type_node), ret);
}

/* Return a CONST_INT representing 4 subsequent shadow memory bytes.  */

static rtx
asan_shadow_cst (unsigned char shadow_bytes[4])
{
  int i;
  unsigned HOST_WIDE_INT val = 0;
  gcc_assert (WORDS_BIG_ENDIAN == BYTES_BIG_ENDIAN);
  for (i = 0; i < 4; i++)
    val |= (unsigned HOST_WIDE_INT) shadow_bytes[BYTES_BIG_ENDIAN ? 3 - i : i]
           << (BITS_PER_UNIT * i);
  return GEN_INT (trunc_int_for_mode (val, SImode));
}

/* Insert code to protect stack vars.  The prologue sequence should be emitted
   directly, epilogue sequence returned.  BASE is the register holding the
   stack base, against which OFFSETS array offsets are relative to, OFFSETS
   array contains pairs of offsets in reverse order, always the end offset
   of some gap that needs protection followed by starting offset,
   and DECLS is an array of representative decls for each var partition.
   LENGTH is the length of the OFFSETS array, DECLS array is LENGTH / 2 - 1
   elements long (OFFSETS include gap before the first variable as well
   as gaps after each stack variable).  */

rtx
asan_emit_stack_protection (rtx base, HOST_WIDE_INT *offsets, tree *decls,
                            int length)
{
  rtx shadow_base, shadow_mem, ret, mem;
  unsigned char shadow_bytes[4];
  HOST_WIDE_INT base_offset = offsets[length - 1], offset, prev_offset;
  HOST_WIDE_INT last_offset, last_size;
  int l;
  unsigned char cur_shadow_byte = ASAN_STACK_MAGIC_LEFT;
  tree str_cst;

  /* First of all, prepare the description string.  */
  if (!asan_pp_initialized)
    asan_pp_initialize ();

  pp_clear_output_area (&asan_pp);
  if (DECL_NAME (current_function_decl))
    pp_base_tree_identifier (&asan_pp, DECL_NAME (current_function_decl));
  else
    pp_string (&asan_pp, "<unknown>");
  pp_space (&asan_pp);
  pp_decimal_int (&asan_pp, length / 2 - 1);
  pp_space (&asan_pp);
  for (l = length - 2; l; l -= 2)
    {
      tree decl = decls[l / 2 - 1];
      pp_wide_integer (&asan_pp, offsets[l] - base_offset);
      pp_space (&asan_pp);
      pp_wide_integer (&asan_pp, offsets[l - 1] - offsets[l]);
      pp_space (&asan_pp);
      if (DECL_P (decl) && DECL_NAME (decl))
        {
          pp_decimal_int (&asan_pp, IDENTIFIER_LENGTH (DECL_NAME (decl)));
          pp_space (&asan_pp);
          pp_base_tree_identifier (&asan_pp, DECL_NAME (decl));
        }
      else
        pp_string (&asan_pp, "9 <unknown>");
      pp_space (&asan_pp);
    }
  str_cst = asan_pp_string ();

  /* Emit the prologue sequence.  */
  base = expand_binop (Pmode, add_optab, base, GEN_INT (base_offset),
                       NULL_RTX, 1, OPTAB_DIRECT);
  mem = gen_rtx_MEM (ptr_mode, base);
  emit_move_insn (mem, GEN_INT (ASAN_STACK_FRAME_MAGIC));
  mem = adjust_address (mem, VOIDmode, GET_MODE_SIZE (ptr_mode));
  emit_move_insn (mem, expand_normal (str_cst));
  shadow_base = expand_binop (Pmode, lshr_optab, base,
                              GEN_INT (ASAN_SHADOW_SHIFT),
                              NULL_RTX, 1, OPTAB_DIRECT);
  shadow_base = expand_binop (Pmode, add_optab, shadow_base,
                              GEN_INT (targetm.asan_shadow_offset ()),
                              NULL_RTX, 1, OPTAB_DIRECT);
  gcc_assert (asan_shadow_set != -1
              && (ASAN_RED_ZONE_SIZE >> ASAN_SHADOW_SHIFT) == 4);
  shadow_mem = gen_rtx_MEM (SImode, shadow_base);
  set_mem_alias_set (shadow_mem, asan_shadow_set);
  prev_offset = base_offset;
  for (l = length; l; l -= 2)
    {
      if (l == 2)
        cur_shadow_byte = ASAN_STACK_MAGIC_RIGHT;
      offset = offsets[l - 1];
      if ((offset - base_offset) & (ASAN_RED_ZONE_SIZE - 1))
        {
          int i;
          HOST_WIDE_INT aoff
            = base_offset + ((offset - base_offset)
                             & ~(ASAN_RED_ZONE_SIZE - HOST_WIDE_INT_1));
          shadow_mem = adjust_address (shadow_mem, VOIDmode,
                                       (aoff - prev_offset)
                                       >> ASAN_SHADOW_SHIFT);
          prev_offset = aoff;
          for (i = 0; i < 4; i++, aoff += (1 << ASAN_SHADOW_SHIFT))
            if (aoff < offset)
              {
                if (aoff < offset - (1 << ASAN_SHADOW_SHIFT) + 1)
                  shadow_bytes[i] = 0;
                else
                  shadow_bytes[i] = offset - aoff;
              }
            else
              shadow_bytes[i] = ASAN_STACK_MAGIC_PARTIAL;
          emit_move_insn (shadow_mem, asan_shadow_cst (shadow_bytes));
          offset = aoff;
        }
      while (offset <= offsets[l - 2] - ASAN_RED_ZONE_SIZE)
        {
          shadow_mem = adjust_address (shadow_mem, VOIDmode,
                                       (offset - prev_offset)
                                       >> ASAN_SHADOW_SHIFT);
          prev_offset = offset;
          memset (shadow_bytes, cur_shadow_byte, 4);
          emit_move_insn (shadow_mem, asan_shadow_cst (shadow_bytes));
          offset += ASAN_RED_ZONE_SIZE;
        }
      cur_shadow_byte = ASAN_STACK_MAGIC_MIDDLE;
    }
  do_pending_stack_adjust ();

  /* Construct epilogue sequence.  */
  start_sequence ();

  shadow_mem = gen_rtx_MEM (BLKmode, shadow_base);
  set_mem_alias_set (shadow_mem, asan_shadow_set);
  prev_offset = base_offset;
  last_offset = base_offset;
  last_size = 0;
  for (l = length; l; l -= 2)
    {
      offset = base_offset + ((offsets[l - 1] - base_offset)
                             & ~(ASAN_RED_ZONE_SIZE - HOST_WIDE_INT_1));
      if (last_offset + last_size != offset)
        {
          shadow_mem = adjust_address (shadow_mem, VOIDmode,
                                       (last_offset - prev_offset)
                                       >> ASAN_SHADOW_SHIFT);
          prev_offset = last_offset;
          clear_storage (shadow_mem, GEN_INT (last_size >> ASAN_SHADOW_SHIFT),
                         BLOCK_OP_NORMAL);
          last_offset = offset;
          last_size = 0;
        }
      last_size += base_offset + ((offsets[l - 2] - base_offset)
                                  & ~(ASAN_RED_ZONE_SIZE - HOST_WIDE_INT_1))
                   - offset;
    }
  if (last_size)
    {
      shadow_mem = adjust_address (shadow_mem, VOIDmode,
                                   (last_offset - prev_offset)
                                   >> ASAN_SHADOW_SHIFT);
      clear_storage (shadow_mem, GEN_INT (last_size >> ASAN_SHADOW_SHIFT),
                     BLOCK_OP_NORMAL);
    }

  do_pending_stack_adjust ();

  ret = get_insns ();
  end_sequence ();
  return ret;
}

/* Return true if DECL, a global var, might be overridden and needs
   therefore a local alias.  */

static bool
asan_needs_local_alias (tree decl)
{
  return DECL_WEAK (decl) || !targetm.binds_local_p (decl);
}

/* Return true if DECL is a VAR_DECL that should be protected
   by Address Sanitizer, by appending a red zone with protected
   shadow memory after it and aligning it to at least
   ASAN_RED_ZONE_SIZE bytes.  */

bool
asan_protect_global (tree decl)
{
  rtx rtl, symbol;
  section *sect;

  if (TREE_CODE (decl) != VAR_DECL
      /* TLS vars aren't statically protectable.  */
      || DECL_THREAD_LOCAL_P (decl)
      /* Externs will be protected elsewhere.  */
      || DECL_EXTERNAL (decl)
      || !TREE_ASM_WRITTEN (decl)
      || !DECL_RTL_SET_P (decl)
      /* Comdat vars pose an ABI problem, we can't know if
         the var that is selected by the linker will have
         padding or not.  */
      || DECL_ONE_ONLY (decl)
      /* Similarly for common vars.  People can use -fno-common.  */
      || DECL_COMMON (decl)
      /* Don't protect if using user section, often vars placed
         into user section from multiple TUs are then assumed
         to be an array of such vars, putting padding in there
         breaks this assumption.  */
      || (DECL_SECTION_NAME (decl) != NULL_TREE
          && !DECL_HAS_IMPLICIT_SECTION_NAME_P (decl))
      || DECL_SIZE (decl) == 0
      || ASAN_RED_ZONE_SIZE * BITS_PER_UNIT > MAX_OFILE_ALIGNMENT
      || !valid_constant_size_p (DECL_SIZE_UNIT (decl))
      || DECL_ALIGN_UNIT (decl) > 2 * ASAN_RED_ZONE_SIZE)
    return false;

  rtl = DECL_RTL (decl);
  if (!MEM_P (rtl) || GET_CODE (XEXP (rtl, 0)) != SYMBOL_REF)
    return false;
  symbol = XEXP (rtl, 0);

  if (CONSTANT_POOL_ADDRESS_P (symbol)
      || TREE_CONSTANT_POOL_ADDRESS_P (symbol))
    return false;

  sect = get_variable_section (decl, false);
  if (sect->common.flags & SECTION_COMMON)
    return false;

  if (lookup_attribute ("weakref", DECL_ATTRIBUTES (decl)))
    return false;

#ifndef ASM_OUTPUT_DEF
  if (asan_needs_local_alias (decl))
    return false;
#endif

  return true;
}

/* Construct a function tree for __asan_report_{load,store}{1,2,4,8,16}.
   IS_STORE is either 1 (for a store) or 0 (for a load).
   SIZE_IN_BYTES is one of 1, 2, 4, 8, 16.  */

static tree
report_error_func (bool is_store, int size_in_bytes)
{
  tree fn_type;
  tree def;
  char name[100];

  sprintf (name, "__asan_report_%s%d",
           is_store ? "store" : "load", size_in_bytes);
  fn_type = build_function_type_list (void_type_node, ptr_type_node, NULL_TREE);
  def = build_fn_decl (name, fn_type);
  TREE_NOTHROW (def) = 1;
  DECL_IGNORED_P (def) = 1;
  TREE_THIS_VOLATILE (def) = 1;  /* Attribute noreturn. Surprise!  */
  DECL_ATTRIBUTES (def) = tree_cons (get_identifier ("leaf"),
                                     NULL, DECL_ATTRIBUTES (def));
  return def;
}

/* Construct a function tree for __asan_init().  */

static tree
asan_init_func (void)
{
  tree fn_type;
  tree def;

  fn_type = build_function_type_list (void_type_node, NULL_TREE);
  def = build_fn_decl ("__asan_init", fn_type);
  TREE_NOTHROW (def) = 1;
  DECL_IGNORED_P (def) = 1;
  return def;
}


#define PROB_VERY_UNLIKELY      (REG_BR_PROB_BASE / 2000 - 1)
#define PROB_ALWAYS             (REG_BR_PROB_BASE)

/* Split the current basic block and create a condition statement
   insertion point right before or after the statement pointed to by
   ITER.  Return an iterator to the point at which the caller might
   safely insert the condition statement.

   THEN_BLOCK must be set to the address of an uninitialized instance
   of basic_block.  The function will then set *THEN_BLOCK to the
   'then block' of the condition statement to be inserted by the
   caller.

   Similarly, the function will set *FALLTRHOUGH_BLOCK to the 'else
   block' of the condition statement to be inserted by the caller.

   Note that *FALLTHROUGH_BLOCK is a new block that contains the
   statements starting from *ITER, and *THEN_BLOCK is a new empty
   block.

   *ITER is adjusted to point to always point to the first statement
    of the basic block * FALLTHROUGH_BLOCK.  That statement is the
    same as what ITER was pointing to prior to calling this function,
    if BEFORE_P is true; otherwise, it is its following statement.  */

static gimple_stmt_iterator
create_cond_insert_point (gimple_stmt_iterator *iter,
                          bool before_p,
                          bool then_more_likely_p,
                          basic_block *then_block,
                          basic_block *fallthrough_block)
{
  gimple_stmt_iterator gsi = *iter;

  if (!gsi_end_p (gsi) && before_p)
    gsi_prev (&gsi);

  basic_block cur_bb = gsi_bb (*iter);

  edge e = split_block (cur_bb, gsi_stmt (gsi));

  /* Get a hold on the 'condition block', the 'then block' and the
     'else block'.  */
  basic_block cond_bb = e->src;
  basic_block fallthru_bb = e->dest;
  basic_block then_bb = create_empty_bb (cond_bb);

  /* Set up the newly created 'then block'.  */
  e = make_edge (cond_bb, then_bb, EDGE_TRUE_VALUE);
  int fallthrough_probability
    = then_more_likely_p
    ? PROB_VERY_UNLIKELY
    : PROB_ALWAYS - PROB_VERY_UNLIKELY;
  e->probability = PROB_ALWAYS - fallthrough_probability;
  make_single_succ_edge (then_bb, fallthru_bb, EDGE_FALLTHRU);

  /* Set up the fallthrough basic block.  */
  e = find_edge (cond_bb, fallthru_bb);
  e->flags = EDGE_FALSE_VALUE;
  e->count = cond_bb->count;
  e->probability = fallthrough_probability;

  /* Update dominance info for the newly created then_bb; note that
     fallthru_bb's dominance info has already been updated by
     split_bock.  */
  if (dom_info_available_p (CDI_DOMINATORS))
    set_immediate_dominator (CDI_DOMINATORS, then_bb, cond_bb);

  *then_block = then_bb;
  *fallthrough_block = fallthru_bb;
  *iter = gsi_start_bb (fallthru_bb);

  return gsi_last_bb (cond_bb);
}

/* Insert an if condition followed by a 'then block' right before the
   statement pointed to by ITER.  The fallthrough block -- which is the
   else block of the condition as well as the destination of the
   outcoming edge of the 'then block' -- starts with the statement
   pointed to by ITER.

   COND is the condition of the if.

   If THEN_MORE_LIKELY_P is true, the probability of the edge to the
   'then block' is higher than the probability of the edge to the
   fallthrough block.

   Upon completion of the function, *THEN_BB is set to the newly
   inserted 'then block' and similarly, *FALLTHROUGH_BB is set to the
   fallthrough block.

   *ITER is adjusted to still point to the same statement it was
   pointing to initially.  */

static void
insert_if_then_before_iter (gimple cond,
                            gimple_stmt_iterator *iter,
                            bool then_more_likely_p,
                            basic_block *then_bb,
                            basic_block *fallthrough_bb)
{
  gimple_stmt_iterator cond_insert_point =
    create_cond_insert_point (iter,
                              /*before_p=*/true,
                              then_more_likely_p,
                              then_bb,
                              fallthrough_bb);
  gsi_insert_after (&cond_insert_point, cond, GSI_NEW_STMT);
}

/* Instrument the memory access instruction BASE.  Insert new
   statements before or after ITER.

   Note that the memory access represented by BASE can be either an
   SSA_NAME, or a non-SSA expression.  LOCATION is the source code
   location.  IS_STORE is TRUE for a store, FALSE for a load.
   BEFORE_P is TRUE for inserting the instrumentation code before
   ITER, FALSE for inserting it after ITER.  SIZE_IN_BYTES is one of
   1, 2, 4, 8, 16.

   If BEFORE_P is TRUE, *ITER is arranged to still point to the
   statement it was pointing to prior to calling this function,
   otherwise, it points to the statement logically following it.  */

static void
build_check_stmt (location_t location, tree base, gimple_stmt_iterator *iter,
                  bool before_p, bool is_store, int size_in_bytes)
{
  gimple_stmt_iterator gsi;
  basic_block then_bb, else_bb;
  tree t, base_addr, shadow;
  gimple g;
  tree shadow_ptr_type = shadow_ptr_types[size_in_bytes == 16 ? 1 : 0];
  tree shadow_type = TREE_TYPE (shadow_ptr_type);
  tree uintptr_type
    = build_nonstandard_integer_type (TYPE_PRECISION (TREE_TYPE (base)), 1);
  tree base_ssa = base;

  /* Get an iterator on the point where we can add the condition
     statement for the instrumentation.  */
  gsi = create_cond_insert_point (iter, before_p,
                                  /*then_more_likely_p=*/false,
                                  &then_bb,
                                  &else_bb);

  base = unshare_expr (base);

  /* BASE can already be an SSA_NAME; in that case, do not create a
     new SSA_NAME for it.  */
  if (TREE_CODE (base) != SSA_NAME)
    {
      g = gimple_build_assign_with_ops (TREE_CODE (base),
                                        make_ssa_name (TREE_TYPE (base), NULL),
                                        base, NULL_TREE);
      gimple_set_location (g, location);
      gsi_insert_after (&gsi, g, GSI_NEW_STMT);
      base_ssa = gimple_assign_lhs (g);
    }

  g = gimple_build_assign_with_ops (NOP_EXPR,
                                    make_ssa_name (uintptr_type, NULL),
                                    base_ssa, NULL_TREE);
  gimple_set_location (g, location);
  gsi_insert_after (&gsi, g, GSI_NEW_STMT);
  base_addr = gimple_assign_lhs (g);

  /* Build
     (base_addr >> ASAN_SHADOW_SHIFT) + targetm.asan_shadow_offset ().  */

  t = build_int_cst (uintptr_type, ASAN_SHADOW_SHIFT);
  g = gimple_build_assign_with_ops (RSHIFT_EXPR,
                                    make_ssa_name (uintptr_type, NULL),
                                    base_addr, t);
  gimple_set_location (g, location);
  gsi_insert_after (&gsi, g, GSI_NEW_STMT);

  t = build_int_cst (uintptr_type, targetm.asan_shadow_offset ());
  g = gimple_build_assign_with_ops (PLUS_EXPR,
                                    make_ssa_name (uintptr_type, NULL),
                                    gimple_assign_lhs (g), t);
  gimple_set_location (g, location);
  gsi_insert_after (&gsi, g, GSI_NEW_STMT);

  g = gimple_build_assign_with_ops (NOP_EXPR,
                                    make_ssa_name (shadow_ptr_type, NULL),
                                    gimple_assign_lhs (g), NULL_TREE);
  gimple_set_location (g, location);
  gsi_insert_after (&gsi, g, GSI_NEW_STMT);

  t = build2 (MEM_REF, shadow_type, gimple_assign_lhs (g),
              build_int_cst (shadow_ptr_type, 0));
  g = gimple_build_assign_with_ops (MEM_REF,
                                    make_ssa_name (shadow_type, NULL),
                                    t, NULL_TREE);
  gimple_set_location (g, location);
  gsi_insert_after (&gsi, g, GSI_NEW_STMT);
  shadow = gimple_assign_lhs (g);

  if (size_in_bytes < 8)
    {
      /* Slow path for 1, 2 and 4 byte accesses.
         Test (shadow != 0)
              & ((base_addr & 7) + (size_in_bytes - 1)) >= shadow).  */
      g = gimple_build_assign_with_ops (NE_EXPR,
                                        make_ssa_name (boolean_type_node,
                                                       NULL),
                                        shadow,
                                        build_int_cst (shadow_type, 0));
      gimple_set_location (g, location);
      gsi_insert_after (&gsi, g, GSI_NEW_STMT);
      t = gimple_assign_lhs (g);

      g = gimple_build_assign_with_ops (BIT_AND_EXPR,
                                        make_ssa_name (uintptr_type,
                                                       NULL),
                                        base_addr,
                                        build_int_cst (uintptr_type, 7));
      gimple_set_location (g, location);
      gsi_insert_after (&gsi, g, GSI_NEW_STMT);

      g = gimple_build_assign_with_ops (NOP_EXPR,
                                        make_ssa_name (shadow_type,
                                                       NULL),
                                        gimple_assign_lhs (g), NULL_TREE);
      gimple_set_location (g, location);
      gsi_insert_after (&gsi, g, GSI_NEW_STMT);

      if (size_in_bytes > 1)
        {
          g = gimple_build_assign_with_ops (PLUS_EXPR,
                                            make_ssa_name (shadow_type,
                                                           NULL),
                                            gimple_assign_lhs (g),
                                            build_int_cst (shadow_type,
                                                           size_in_bytes - 1));
          gimple_set_location (g, location);
          gsi_insert_after (&gsi, g, GSI_NEW_STMT);
        }

      g = gimple_build_assign_with_ops (GE_EXPR,
                                        make_ssa_name (boolean_type_node,
                                                       NULL),
                                        gimple_assign_lhs (g),
                                        shadow);
      gimple_set_location (g, location);
      gsi_insert_after (&gsi, g, GSI_NEW_STMT);

      g = gimple_build_assign_with_ops (BIT_AND_EXPR,
                                        make_ssa_name (boolean_type_node,
                                                       NULL),
                                        t, gimple_assign_lhs (g));
      gimple_set_location (g, location);
      gsi_insert_after (&gsi, g, GSI_NEW_STMT);
      t = gimple_assign_lhs (g);
    }
  else
    t = shadow;

  g = gimple_build_cond (NE_EXPR, t, build_int_cst (TREE_TYPE (t), 0),
                         NULL_TREE, NULL_TREE);
  gimple_set_location (g, location);
  gsi_insert_after (&gsi, g, GSI_NEW_STMT);

  /* Generate call to the run-time library (e.g. __asan_report_load8).  */
  gsi = gsi_start_bb (then_bb);
  g = gimple_build_call (report_error_func (is_store, size_in_bytes),
                         1, base_addr);
  gimple_set_location (g, location);
  gsi_insert_after (&gsi, g, GSI_NEW_STMT);

  *iter = gsi_start_bb (else_bb);
}

/* If T represents a memory access, add instrumentation code before ITER.
   LOCATION is source code location.
   IS_STORE is either TRUE (for a store) or FALSE (for a load).  */

static void
instrument_derefs (gimple_stmt_iterator *iter, tree t,
                  location_t location, bool is_store)
{
  tree type, base;
  HOST_WIDE_INT size_in_bytes;

  type = TREE_TYPE (t);
  switch (TREE_CODE (t))
    {
    case ARRAY_REF:
    case COMPONENT_REF:
    case INDIRECT_REF:
    case MEM_REF:
      break;
    default:
      return;
    }

  size_in_bytes = int_size_in_bytes (type);
  if ((size_in_bytes & (size_in_bytes - 1)) != 0
      || (unsigned HOST_WIDE_INT) size_in_bytes - 1 >= 16)
    return;

  /* For now just avoid instrumenting bit field acceses.
     Fixing it is doable, but expected to be messy.  */

  HOST_WIDE_INT bitsize, bitpos;
  tree offset;
  enum machine_mode mode;
  int volatilep = 0, unsignedp = 0;
  get_inner_reference (t, &bitsize, &bitpos, &offset,
                       &mode, &unsignedp, &volatilep, false);
  if (bitpos % (size_in_bytes * BITS_PER_UNIT)
      || bitsize != size_in_bytes * BITS_PER_UNIT)
    return;

  base = build_fold_addr_expr (t);
  build_check_stmt (location, base, iter, /*before_p=*/true,
                    is_store, size_in_bytes);
}

/* Instrument an access to a contiguous memory region that starts at
   the address pointed to by BASE, over a length of LEN (expressed in
   the sizeof (*BASE) bytes).  ITER points to the instruction before
   which the instrumentation instructions must be inserted.  LOCATION
   is the source location that the instrumentation instructions must
   have.  If IS_STORE is true, then the memory access is a store;
   otherwise, it's a load.  */

static void
instrument_mem_region_access (tree base, tree len,
                              gimple_stmt_iterator *iter,
                              location_t location, bool is_store)
{
  if (integer_zerop (len))
    return;

  gimple_stmt_iterator gsi = *iter;

  basic_block fallthrough_bb = NULL, then_bb = NULL;
  if (!is_gimple_constant (len))
    {
      /* So, the length of the memory area to asan-protect is
         non-constant.  Let's guard the generated instrumentation code
         like:

         if (len != 0)
           {
             //asan instrumentation code goes here.
           }
           // falltrough instructions, starting with *ITER.  */

      gimple g = gimple_build_cond (NE_EXPR,
                                    len,
                                    build_int_cst (TREE_TYPE (len), 0),
                                    NULL_TREE, NULL_TREE);
      gimple_set_location (g, location);
      insert_if_then_before_iter (g, iter, /*then_more_likely_p=*/true,
                                  &then_bb, &fallthrough_bb);
      /* Note that fallthrough_bb starts with the statement that was
         pointed to by ITER.  */

      /* The 'then block' of the 'if (len != 0) condition is where
         we'll generate the asan instrumentation code now.  */
      gsi = gsi_start_bb (then_bb);
    }

  /* Instrument the beginning of the memory region to be accessed,
     and arrange for the rest of the intrumentation code to be
     inserted in the then block *after* the current gsi.  */
  build_check_stmt (location, base, &gsi, /*before_p=*/true, is_store, 1);

  if (then_bb)
    /* We are in the case where the length of the region is not
       constant; so instrumentation code is being generated in the
       'then block' of the 'if (len != 0) condition.  Let's arrange
       for the subsequent instrumentation statements to go in the
       'then block'.  */
    gsi = gsi_last_bb (then_bb);
  else
    *iter = gsi;

  /* We want to instrument the access at the end of the memory region,
     which is at (base + len - 1).  */

  /* offset = len - 1;  */
  len = unshare_expr (len);
  gimple offset =
    gimple_build_assign_with_ops (TREE_CODE (len),
                                  make_ssa_name (TREE_TYPE (len), NULL),
                                  len, NULL);
  gimple_set_location (offset, location);
  gsi_insert_before (&gsi, offset, GSI_NEW_STMT);

  offset =
    gimple_build_assign_with_ops (MINUS_EXPR,
                                  make_ssa_name (size_type_node, NULL),
                                  gimple_assign_lhs (offset),
                                  build_int_cst (size_type_node, 1));
  gimple_set_location (offset, location);
  gsi_insert_after (&gsi, offset, GSI_NEW_STMT);

  /* _1 = base;  */
  base = unshare_expr (base);
  gimple region_end =
    gimple_build_assign_with_ops (TREE_CODE (base),
                                  make_ssa_name (TREE_TYPE (base), NULL),
                                  base, NULL);
  gimple_set_location (region_end, location);
  gsi_insert_after (&gsi, region_end, GSI_NEW_STMT);

  /* _2 = _1 + offset;  */
  region_end =
    gimple_build_assign_with_ops (POINTER_PLUS_EXPR,
                                  make_ssa_name (TREE_TYPE (base), NULL),
                                  gimple_assign_lhs (region_end),
                                  gimple_assign_lhs (offset));
  gimple_set_location (region_end, location);
  gsi_insert_after (&gsi, region_end, GSI_NEW_STMT);

  /* instrument access at _2;  */
  build_check_stmt (location, gimple_assign_lhs (region_end),
                    &gsi, /*before_p=*/false, is_store, 1);
}

/* Instrument the call (to the builtin strlen function) pointed to by
   ITER.

   This function instruments the access to the first byte of the
   argument, right before the call.  After the call it instruments the
   access to the last byte of the argument; it uses the result of the
   call to deduce the offset of that last byte.

   Upon completion, iff the call has actullay been instrumented, this
   function returns TRUE and *ITER points to the statement logically
   following the built-in strlen function call *ITER was initially
   pointing to.  Otherwise, the function returns FALSE and *ITER
   remains unchanged.  */

static bool
instrument_strlen_call (gimple_stmt_iterator *iter)
{
  gimple call = gsi_stmt (*iter);
  gcc_assert (is_gimple_call (call));

  tree callee = gimple_call_fndecl (call);
  gcc_assert (is_builtin_fn (callee)
              && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL
              && DECL_FUNCTION_CODE (callee) == BUILT_IN_STRLEN);

  tree len = gimple_call_lhs (call);
  if (len == NULL)
    /* Some passes might clear the return value of the strlen call;
       bail out in that case.  Return FALSE as we are not advancing
       *ITER.  */
    return false;
  gcc_assert (INTEGRAL_TYPE_P (TREE_TYPE (len)));

  location_t loc = gimple_location (call);
  tree str_arg = gimple_call_arg (call, 0);

  /* Instrument the access to the first byte of str_arg.  i.e:

     _1 = str_arg; instrument (_1); */
  gimple str_arg_ssa =
    gimple_build_assign_with_ops (NOP_EXPR,
                                  make_ssa_name (build_pointer_type
                                                 (char_type_node), NULL),
                                  str_arg, NULL);
  gimple_set_location (str_arg_ssa, loc);
  gimple_stmt_iterator gsi = *iter;
  gsi_insert_before (&gsi, str_arg_ssa, GSI_NEW_STMT);
  build_check_stmt (loc, gimple_assign_lhs (str_arg_ssa), &gsi,
                    /*before_p=*/false, /*is_store=*/false, 1);

  /* If we initially had an instruction like:

         int n = strlen (str)

     we now want to instrument the access to str[n], after the
     instruction above.*/

  /* So let's build the access to str[n] that is, access through the
     pointer_plus expr: (_1 + len).  */
  gimple stmt =
    gimple_build_assign_with_ops (POINTER_PLUS_EXPR,
                                  make_ssa_name (TREE_TYPE (str_arg),
                                                 NULL),
                                  gimple_assign_lhs (str_arg_ssa),
                                  len);
  gimple_set_location (stmt, loc);
  gsi_insert_after (&gsi, stmt, GSI_NEW_STMT);

  build_check_stmt (loc, gimple_assign_lhs (stmt), &gsi,
                    /*before_p=*/false, /*is_store=*/false, 1);

  /* Ensure that iter points to the statement logically following the
     one it was initially pointing to.  */
  *iter = gsi;
  /* As *ITER has been advanced to point to the next statement, let's
     return true to inform transform_statements that it shouldn't
     advance *ITER anymore; otherwises it will skip that next
     statement, which wouldn't be instrumented.  */
  return true;
}

/* Instrument the call to a built-in memory access function that is
   pointed to by the iterator ITER.

   Upon completion, return TRUE iff *ITER has been advanced to the
   statement following the one it was originally pointing to.  */

static bool
instrument_builtin_call (gimple_stmt_iterator *iter)
{
  gimple call = gsi_stmt (*iter);

  gcc_assert (is_gimple_builtin_call (call));

  tree callee = gimple_call_fndecl (call);
  location_t loc = gimple_location (call);
  tree source0 = NULL_TREE, source1 = NULL_TREE,
    dest = NULL_TREE, len = NULL_TREE;
  bool is_store = true;

  switch (DECL_FUNCTION_CODE (callee))
    {
      /* (s, s, n) style memops.  */
    case BUILT_IN_BCMP:
    case BUILT_IN_MEMCMP:
      source0 = gimple_call_arg (call, 0);
      source1 = gimple_call_arg (call, 1);
      len = gimple_call_arg (call, 2);
      break;

      /* (src, dest, n) style memops.  */
    case BUILT_IN_BCOPY:
      source0 = gimple_call_arg (call, 0);
      dest = gimple_call_arg (call, 1);
      len = gimple_call_arg (call, 2);
      break;

      /* (dest, src, n) style memops.  */
    case BUILT_IN_MEMCPY:
    case BUILT_IN_MEMCPY_CHK:
    case BUILT_IN_MEMMOVE:
    case BUILT_IN_MEMMOVE_CHK:
    case BUILT_IN_MEMPCPY:
    case BUILT_IN_MEMPCPY_CHK:
      dest = gimple_call_arg (call, 0);
      source0 = gimple_call_arg (call, 1);
      len = gimple_call_arg (call, 2);
      break;

      /* (dest, n) style memops.  */
    case BUILT_IN_BZERO:
      dest = gimple_call_arg (call, 0);
      len = gimple_call_arg (call, 1);
      break;

      /* (dest, x, n) style memops*/
    case BUILT_IN_MEMSET:
    case BUILT_IN_MEMSET_CHK:
      dest = gimple_call_arg (call, 0);
      len = gimple_call_arg (call, 2);
      break;

    case BUILT_IN_STRLEN:
      return instrument_strlen_call (iter);

    /* And now the __atomic* and __sync builtins.
       These are handled differently from the classical memory memory
       access builtins above.  */

    case BUILT_IN_ATOMIC_LOAD:
    case BUILT_IN_ATOMIC_LOAD_1:
    case BUILT_IN_ATOMIC_LOAD_2:
    case BUILT_IN_ATOMIC_LOAD_4:
    case BUILT_IN_ATOMIC_LOAD_8:
    case BUILT_IN_ATOMIC_LOAD_16:
      is_store = false;
      /* fall through.  */

    case BUILT_IN_SYNC_FETCH_AND_ADD_1:
    case BUILT_IN_SYNC_FETCH_AND_ADD_2:
    case BUILT_IN_SYNC_FETCH_AND_ADD_4:
    case BUILT_IN_SYNC_FETCH_AND_ADD_8:
    case BUILT_IN_SYNC_FETCH_AND_ADD_16:

    case BUILT_IN_SYNC_FETCH_AND_SUB_1:
    case BUILT_IN_SYNC_FETCH_AND_SUB_2:
    case BUILT_IN_SYNC_FETCH_AND_SUB_4:
    case BUILT_IN_SYNC_FETCH_AND_SUB_8:
    case BUILT_IN_SYNC_FETCH_AND_SUB_16:

    case BUILT_IN_SYNC_FETCH_AND_OR_1:
    case BUILT_IN_SYNC_FETCH_AND_OR_2:
    case BUILT_IN_SYNC_FETCH_AND_OR_4:
    case BUILT_IN_SYNC_FETCH_AND_OR_8:
    case BUILT_IN_SYNC_FETCH_AND_OR_16:

    case BUILT_IN_SYNC_FETCH_AND_AND_1:
    case BUILT_IN_SYNC_FETCH_AND_AND_2:
    case BUILT_IN_SYNC_FETCH_AND_AND_4:
    case BUILT_IN_SYNC_FETCH_AND_AND_8:
    case BUILT_IN_SYNC_FETCH_AND_AND_16:

    case BUILT_IN_SYNC_FETCH_AND_XOR_1:
    case BUILT_IN_SYNC_FETCH_AND_XOR_2:
    case BUILT_IN_SYNC_FETCH_AND_XOR_4:
    case BUILT_IN_SYNC_FETCH_AND_XOR_8:
    case BUILT_IN_SYNC_FETCH_AND_XOR_16:

    case BUILT_IN_SYNC_FETCH_AND_NAND_1:
    case BUILT_IN_SYNC_FETCH_AND_NAND_2:
    case BUILT_IN_SYNC_FETCH_AND_NAND_4:
    case BUILT_IN_SYNC_FETCH_AND_NAND_8:

    case BUILT_IN_SYNC_ADD_AND_FETCH_1:
    case BUILT_IN_SYNC_ADD_AND_FETCH_2:
    case BUILT_IN_SYNC_ADD_AND_FETCH_4:
    case BUILT_IN_SYNC_ADD_AND_FETCH_8:
    case BUILT_IN_SYNC_ADD_AND_FETCH_16:

    case BUILT_IN_SYNC_SUB_AND_FETCH_1:
    case BUILT_IN_SYNC_SUB_AND_FETCH_2:
    case BUILT_IN_SYNC_SUB_AND_FETCH_4:
    case BUILT_IN_SYNC_SUB_AND_FETCH_8:
    case BUILT_IN_SYNC_SUB_AND_FETCH_16:

    case BUILT_IN_SYNC_OR_AND_FETCH_1:
    case BUILT_IN_SYNC_OR_AND_FETCH_2:
    case BUILT_IN_SYNC_OR_AND_FETCH_4:
    case BUILT_IN_SYNC_OR_AND_FETCH_8:
    case BUILT_IN_SYNC_OR_AND_FETCH_16:

    case BUILT_IN_SYNC_AND_AND_FETCH_1:
    case BUILT_IN_SYNC_AND_AND_FETCH_2:
    case BUILT_IN_SYNC_AND_AND_FETCH_4:
    case BUILT_IN_SYNC_AND_AND_FETCH_8:
    case BUILT_IN_SYNC_AND_AND_FETCH_16:

    case BUILT_IN_SYNC_XOR_AND_FETCH_1:
    case BUILT_IN_SYNC_XOR_AND_FETCH_2:
    case BUILT_IN_SYNC_XOR_AND_FETCH_4:
    case BUILT_IN_SYNC_XOR_AND_FETCH_8:
    case BUILT_IN_SYNC_XOR_AND_FETCH_16:

    case BUILT_IN_SYNC_NAND_AND_FETCH_1:
    case BUILT_IN_SYNC_NAND_AND_FETCH_2:
    case BUILT_IN_SYNC_NAND_AND_FETCH_4:
    case BUILT_IN_SYNC_NAND_AND_FETCH_8:

    case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_1:
    case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_2:
    case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_4:
    case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_8:
    case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_16:

    case BUILT_IN_SYNC_VAL_COMPARE_AND_SWAP_1:
    case BUILT_IN_SYNC_VAL_COMPARE_AND_SWAP_2:
    case BUILT_IN_SYNC_VAL_COMPARE_AND_SWAP_4:
    case BUILT_IN_SYNC_VAL_COMPARE_AND_SWAP_8:
    case BUILT_IN_SYNC_VAL_COMPARE_AND_SWAP_16:

    case BUILT_IN_SYNC_LOCK_TEST_AND_SET_1:
    case BUILT_IN_SYNC_LOCK_TEST_AND_SET_2:
    case BUILT_IN_SYNC_LOCK_TEST_AND_SET_4:
    case BUILT_IN_SYNC_LOCK_TEST_AND_SET_8:
    case BUILT_IN_SYNC_LOCK_TEST_AND_SET_16:

    case BUILT_IN_SYNC_LOCK_RELEASE_1:
    case BUILT_IN_SYNC_LOCK_RELEASE_2:
    case BUILT_IN_SYNC_LOCK_RELEASE_4:
    case BUILT_IN_SYNC_LOCK_RELEASE_8:
    case BUILT_IN_SYNC_LOCK_RELEASE_16:

    case BUILT_IN_ATOMIC_TEST_AND_SET:
    case BUILT_IN_ATOMIC_CLEAR:
    case BUILT_IN_ATOMIC_EXCHANGE:
    case BUILT_IN_ATOMIC_EXCHANGE_1:
    case BUILT_IN_ATOMIC_EXCHANGE_2:
    case BUILT_IN_ATOMIC_EXCHANGE_4:
    case BUILT_IN_ATOMIC_EXCHANGE_8:
    case BUILT_IN_ATOMIC_EXCHANGE_16:

    case BUILT_IN_ATOMIC_COMPARE_EXCHANGE:
    case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_1:
    case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_2:
    case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_4:
    case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_8:
    case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_16:

    case BUILT_IN_ATOMIC_STORE:
    case BUILT_IN_ATOMIC_STORE_1:
    case BUILT_IN_ATOMIC_STORE_2:
    case BUILT_IN_ATOMIC_STORE_4:
    case BUILT_IN_ATOMIC_STORE_8:
    case BUILT_IN_ATOMIC_STORE_16:

    case BUILT_IN_ATOMIC_ADD_FETCH_1:
    case BUILT_IN_ATOMIC_ADD_FETCH_2:
    case BUILT_IN_ATOMIC_ADD_FETCH_4:
    case BUILT_IN_ATOMIC_ADD_FETCH_8:
    case BUILT_IN_ATOMIC_ADD_FETCH_16:

    case BUILT_IN_ATOMIC_SUB_FETCH_1:
    case BUILT_IN_ATOMIC_SUB_FETCH_2:
    case BUILT_IN_ATOMIC_SUB_FETCH_4:
    case BUILT_IN_ATOMIC_SUB_FETCH_8:
    case BUILT_IN_ATOMIC_SUB_FETCH_16:

    case BUILT_IN_ATOMIC_AND_FETCH_1:
    case BUILT_IN_ATOMIC_AND_FETCH_2:
    case BUILT_IN_ATOMIC_AND_FETCH_4:
    case BUILT_IN_ATOMIC_AND_FETCH_8:
    case BUILT_IN_ATOMIC_AND_FETCH_16:

    case BUILT_IN_ATOMIC_NAND_FETCH_1:
    case BUILT_IN_ATOMIC_NAND_FETCH_2:
    case BUILT_IN_ATOMIC_NAND_FETCH_4:
    case BUILT_IN_ATOMIC_NAND_FETCH_8:
    case BUILT_IN_ATOMIC_NAND_FETCH_16:

    case BUILT_IN_ATOMIC_XOR_FETCH_1:
    case BUILT_IN_ATOMIC_XOR_FETCH_2:
    case BUILT_IN_ATOMIC_XOR_FETCH_4:
    case BUILT_IN_ATOMIC_XOR_FETCH_8:
    case BUILT_IN_ATOMIC_XOR_FETCH_16:

    case BUILT_IN_ATOMIC_OR_FETCH_1:
    case BUILT_IN_ATOMIC_OR_FETCH_2:
    case BUILT_IN_ATOMIC_OR_FETCH_4:
    case BUILT_IN_ATOMIC_OR_FETCH_8:
    case BUILT_IN_ATOMIC_OR_FETCH_16:

    case BUILT_IN_ATOMIC_FETCH_ADD_1:
    case BUILT_IN_ATOMIC_FETCH_ADD_2:
    case BUILT_IN_ATOMIC_FETCH_ADD_4:
    case BUILT_IN_ATOMIC_FETCH_ADD_8:
    case BUILT_IN_ATOMIC_FETCH_ADD_16:

    case BUILT_IN_ATOMIC_FETCH_SUB_1:
    case BUILT_IN_ATOMIC_FETCH_SUB_2:
    case BUILT_IN_ATOMIC_FETCH_SUB_4:
    case BUILT_IN_ATOMIC_FETCH_SUB_8:
    case BUILT_IN_ATOMIC_FETCH_SUB_16:

    case BUILT_IN_ATOMIC_FETCH_AND_1:
    case BUILT_IN_ATOMIC_FETCH_AND_2:
    case BUILT_IN_ATOMIC_FETCH_AND_4:
    case BUILT_IN_ATOMIC_FETCH_AND_8:
    case BUILT_IN_ATOMIC_FETCH_AND_16:

    case BUILT_IN_ATOMIC_FETCH_NAND_1:
    case BUILT_IN_ATOMIC_FETCH_NAND_2:
    case BUILT_IN_ATOMIC_FETCH_NAND_4:
    case BUILT_IN_ATOMIC_FETCH_NAND_8:
    case BUILT_IN_ATOMIC_FETCH_NAND_16:

    case BUILT_IN_ATOMIC_FETCH_XOR_1:
    case BUILT_IN_ATOMIC_FETCH_XOR_2:
    case BUILT_IN_ATOMIC_FETCH_XOR_4:
    case BUILT_IN_ATOMIC_FETCH_XOR_8:
    case BUILT_IN_ATOMIC_FETCH_XOR_16:

    case BUILT_IN_ATOMIC_FETCH_OR_1:
    case BUILT_IN_ATOMIC_FETCH_OR_2:
    case BUILT_IN_ATOMIC_FETCH_OR_4:
    case BUILT_IN_ATOMIC_FETCH_OR_8:
    case BUILT_IN_ATOMIC_FETCH_OR_16:
      {
        dest = gimple_call_arg (call, 0);
        /* So DEST represents the address of a memory location.
           instrument_derefs wants the memory location, so lets
           dereference the address DEST before handing it to
           instrument_derefs.  */
        if (TREE_CODE (dest) == ADDR_EXPR)
          dest = TREE_OPERAND (dest, 0);
        else if (TREE_CODE (dest) == SSA_NAME)
          dest = build2 (MEM_REF, TREE_TYPE (TREE_TYPE (dest)),
                         dest, build_int_cst (TREE_TYPE (dest), 0));
        else
          gcc_unreachable ();

        instrument_derefs (iter, dest, loc, is_store);
        return false;
      }

    default:
      /* The other builtins memory access are not instrumented in this
         function because they either don't have any length parameter,
         or their length parameter is just a limit.  */
      break;
    }

  if (len != NULL_TREE)
    {
      if (source0 != NULL_TREE)
        instrument_mem_region_access (source0, len, iter,
                                      loc, /*is_store=*/false);
      if (source1 != NULL_TREE)
        instrument_mem_region_access (source1, len, iter,
                                      loc, /*is_store=*/false);
      else if (dest != NULL_TREE)
        instrument_mem_region_access (dest, len, iter,
                                      loc, /*is_store=*/true);

      *iter = gsi_for_stmt (call);
      return false;
    }
  return false;
}

/*  Instrument the assignment statement ITER if it is subject to
    instrumentation.  */

static void
instrument_assignment (gimple_stmt_iterator *iter)
{
  gimple s = gsi_stmt (*iter);

  gcc_assert (gimple_assign_single_p (s));

  instrument_derefs (iter, gimple_assign_lhs (s),
                     gimple_location (s), true);
  instrument_derefs (iter, gimple_assign_rhs1 (s),
                     gimple_location (s), false);
}

/* Instrument the function call pointed to by the iterator ITER, if it
   is subject to instrumentation.  At the moment, the only function
   calls that are instrumented are some built-in functions that access
   memory.  Look at instrument_builtin_call to learn more.

   Upon completion return TRUE iff *ITER was advanced to the statement
   following the one it was originally pointing to.  */

static bool
maybe_instrument_call (gimple_stmt_iterator *iter)
{
  if (is_gimple_builtin_call (gsi_stmt (*iter)))
    return instrument_builtin_call (iter);
  return false;
}

/* asan: this looks too complex. Can this be done simpler? */
/* Transform
   1) Memory references.
   2) BUILTIN_ALLOCA calls.
*/

static void
transform_statements (void)
{
  basic_block bb;
  gimple_stmt_iterator i;
  int saved_last_basic_block = last_basic_block;

  FOR_EACH_BB (bb)
    {
      if (bb->index >= saved_last_basic_block) continue;
      for (i = gsi_start_bb (bb); !gsi_end_p (i);)
        {
          gimple s = gsi_stmt (i);

          if (gimple_assign_single_p (s))
            instrument_assignment (&i);
          else if (is_gimple_call (s))
            {
              if (maybe_instrument_call (&i))
                /* Avoid gsi_next (&i), because maybe_instrument_call
                   advanced the I iterator already.  */
                continue;
            }
          gsi_next (&i);
        }
    }
}

/* Build
   struct __asan_global
   {
     const void *__beg;
     uptr __size;
     uptr __size_with_redzone;
     const void *__name;
     uptr __has_dynamic_init;
   } type.  */

static tree
asan_global_struct (void)
{
  static const char *field_names[5]
    = { "__beg", "__size", "__size_with_redzone",
        "__name", "__has_dynamic_init" };
  tree fields[5], ret;
  int i;

  ret = make_node (RECORD_TYPE);
  for (i = 0; i < 5; i++)
    {
      fields[i]
        = build_decl (UNKNOWN_LOCATION, FIELD_DECL,
                      get_identifier (field_names[i]),
                      (i == 0 || i == 3) ? const_ptr_type_node
                      : build_nonstandard_integer_type (POINTER_SIZE, 1));
      DECL_CONTEXT (fields[i]) = ret;
      if (i)
        DECL_CHAIN (fields[i - 1]) = fields[i];
    }
  TYPE_FIELDS (ret) = fields[0];
  TYPE_NAME (ret) = get_identifier ("__asan_global");
  layout_type (ret);
  return ret;
}

/* Append description of a single global DECL into vector V.
   TYPE is __asan_global struct type as returned by asan_global_struct.  */

static void
asan_add_global (tree decl, tree type, vec<constructor_elt, va_gc> *v)
{
  tree init, uptr = TREE_TYPE (DECL_CHAIN (TYPE_FIELDS (type)));
  unsigned HOST_WIDE_INT size;
  tree str_cst, refdecl = decl;
  vec<constructor_elt, va_gc> *vinner = NULL;

  if (!asan_pp_initialized)
    asan_pp_initialize ();

  pp_clear_output_area (&asan_pp);
  if (DECL_NAME (decl))
    pp_base_tree_identifier (&asan_pp, DECL_NAME (decl));
  else
    pp_string (&asan_pp, "<unknown>");
  pp_space (&asan_pp);
  pp_left_paren (&asan_pp);
  pp_string (&asan_pp, main_input_filename);
  pp_right_paren (&asan_pp);
  str_cst = asan_pp_string ();

  if (asan_needs_local_alias (decl))
    {
      char buf[20];
      ASM_GENERATE_INTERNAL_LABEL (buf, "LASAN", vec_safe_length (v) + 1);
      refdecl = build_decl (DECL_SOURCE_LOCATION (decl),
                            VAR_DECL, get_identifier (buf), TREE_TYPE (decl));
      TREE_ADDRESSABLE (refdecl) = TREE_ADDRESSABLE (decl);
      TREE_READONLY (refdecl) = TREE_READONLY (decl);
      TREE_THIS_VOLATILE (refdecl) = TREE_THIS_VOLATILE (decl);
      DECL_GIMPLE_REG_P (refdecl) = DECL_GIMPLE_REG_P (decl);
      DECL_ARTIFICIAL (refdecl) = DECL_ARTIFICIAL (decl);
      DECL_IGNORED_P (refdecl) = DECL_IGNORED_P (decl);
      TREE_STATIC (refdecl) = 1;
      TREE_PUBLIC (refdecl) = 0;
      TREE_USED (refdecl) = 1;
      assemble_alias (refdecl, DECL_ASSEMBLER_NAME (decl));
    }

  CONSTRUCTOR_APPEND_ELT (vinner, NULL_TREE,
                          fold_convert (const_ptr_type_node,
                                        build_fold_addr_expr (refdecl)));
  size = tree_low_cst (DECL_SIZE_UNIT (decl), 1);
  CONSTRUCTOR_APPEND_ELT (vinner, NULL_TREE, build_int_cst (uptr, size));
  size += asan_red_zone_size (size);
  CONSTRUCTOR_APPEND_ELT (vinner, NULL_TREE, build_int_cst (uptr, size));
  CONSTRUCTOR_APPEND_ELT (vinner, NULL_TREE,
                          fold_convert (const_ptr_type_node, str_cst));
  CONSTRUCTOR_APPEND_ELT (vinner, NULL_TREE, build_int_cst (uptr, 0));
  init = build_constructor (type, vinner);
  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, init);
}

/* Needs to be GTY(()), because cgraph_build_static_cdtor may
   invoke ggc_collect.  */
static GTY(()) tree asan_ctor_statements;

/* Module-level instrumentation.
   - Insert __asan_init() into the list of CTORs.
   - TODO: insert redzones around globals.
 */

void
asan_finish_file (void)
{
  struct varpool_node *vnode;
  unsigned HOST_WIDE_INT gcount = 0;

  append_to_statement_list (build_call_expr (asan_init_func (), 0),
                            &asan_ctor_statements);
  FOR_EACH_DEFINED_VARIABLE (vnode)
    if (asan_protect_global (vnode->symbol.decl))
      ++gcount;
  if (gcount)
    {
      tree type = asan_global_struct (), var, ctor, decl;
      tree uptr = build_nonstandard_integer_type (POINTER_SIZE, 1);
      tree dtor_statements = NULL_TREE;
      vec<constructor_elt, va_gc> *v;
      char buf[20];

      type = build_array_type_nelts (type, gcount);
      ASM_GENERATE_INTERNAL_LABEL (buf, "LASAN", 0);
      var = build_decl (UNKNOWN_LOCATION, VAR_DECL, get_identifier (buf),
                        type);
      TREE_STATIC (var) = 1;
      TREE_PUBLIC (var) = 0;
      DECL_ARTIFICIAL (var) = 1;
      DECL_IGNORED_P (var) = 1;
      vec_alloc (v, gcount);
      FOR_EACH_DEFINED_VARIABLE (vnode)
        if (asan_protect_global (vnode->symbol.decl))
          asan_add_global (vnode->symbol.decl, TREE_TYPE (type), v);
      ctor = build_constructor (type, v);
      TREE_CONSTANT (ctor) = 1;
      TREE_STATIC (ctor) = 1;
      DECL_INITIAL (var) = ctor;
      varpool_assemble_decl (varpool_node_for_decl (var));

      type = build_function_type_list (void_type_node, ptr_type_node,
                                       uptr, NULL_TREE);
      decl = build_fn_decl ("__asan_register_globals", type);
      TREE_NOTHROW (decl) = 1;
      DECL_IGNORED_P (decl) = 1;
      append_to_statement_list (build_call_expr (decl, 2,
                                                 build_fold_addr_expr (var),
                                                 build_int_cst (uptr, gcount)),
                                &asan_ctor_statements);

      decl = build_fn_decl ("__asan_unregister_globals", type);
      TREE_NOTHROW (decl) = 1;
      DECL_IGNORED_P (decl) = 1;
      append_to_statement_list (build_call_expr (decl, 2,
                                                 build_fold_addr_expr (var),
                                                 build_int_cst (uptr, gcount)),
                                &dtor_statements);
      cgraph_build_static_cdtor ('D', dtor_statements,
                                 MAX_RESERVED_INIT_PRIORITY - 1);
    }
  cgraph_build_static_cdtor ('I', asan_ctor_statements,
                             MAX_RESERVED_INIT_PRIORITY - 1);
}

/* Initialize shadow_ptr_types array.  */

static void
asan_init_shadow_ptr_types (void)
{
  asan_shadow_set = new_alias_set ();
  shadow_ptr_types[0] = build_distinct_type_copy (signed_char_type_node);
  TYPE_ALIAS_SET (shadow_ptr_types[0]) = asan_shadow_set;
  shadow_ptr_types[0] = build_pointer_type (shadow_ptr_types[0]);
  shadow_ptr_types[1] = build_distinct_type_copy (short_integer_type_node);
  TYPE_ALIAS_SET (shadow_ptr_types[1]) = asan_shadow_set;
  shadow_ptr_types[1] = build_pointer_type (shadow_ptr_types[1]);
}

/* Instrument the current function.  */

static unsigned int
asan_instrument (void)
{
  if (shadow_ptr_types[0] == NULL_TREE)
    asan_init_shadow_ptr_types ();
  transform_statements ();
  return 0;
}

static bool
gate_asan (void)
{
  return flag_asan != 0;
}

struct gimple_opt_pass pass_asan =
{
 {
  GIMPLE_PASS,
  "asan",                               /* name  */
  OPTGROUP_NONE,                        /* optinfo_flags */
  gate_asan,                            /* gate  */
  asan_instrument,                      /* execute  */
  NULL,                                 /* sub  */
  NULL,                                 /* next  */
  0,                                    /* static_pass_number  */
  TV_NONE,                              /* tv_id  */
  PROP_ssa | PROP_cfg | PROP_gimple_leh,/* properties_required  */
  0,                                    /* properties_provided  */
  0,                                    /* properties_destroyed  */
  0,                                    /* todo_flags_start  */
  TODO_verify_flow | TODO_verify_stmts
  | TODO_update_ssa                     /* todo_flags_finish  */
 }
};

static bool
gate_asan_O0 (void)
{
  return flag_asan != 0 && !optimize;
}

struct gimple_opt_pass pass_asan_O0 =
{
 {
  GIMPLE_PASS,
  "asan0",                              /* name  */
  OPTGROUP_NONE,                        /* optinfo_flags */
  gate_asan_O0,                         /* gate  */
  asan_instrument,                      /* execute  */
  NULL,                                 /* sub  */
  NULL,                                 /* next  */
  0,                                    /* static_pass_number  */
  TV_NONE,                              /* tv_id  */
  PROP_ssa | PROP_cfg | PROP_gimple_leh,/* properties_required  */
  0,                                    /* properties_provided  */
  0,                                    /* properties_destroyed  */
  0,                                    /* todo_flags_start  */
  TODO_verify_flow | TODO_verify_stmts
  | TODO_update_ssa                     /* todo_flags_finish  */
 }
};

#include "gt-asan.h"