xref: /external/valgrind/main/drd/drd_bitmap.c

/*
  This file is part of drd, a thread error detector.

  Copyright (C) 2006-2013 Bart Van Assche <bvanassche@acm.org>.

  This program 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 2 of the
  License, or (at your option) any later version.

  This program 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 this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  02111-1307, USA.

  The GNU General Public License is contained in the file COPYING.
*/


#include "drd_basics.h"           /* DRD_() */
#include "drd_bitmap.h"
#include "drd_error.h"
#include "drd_suppression.h"
#include "pub_drd_bitmap.h"
#include "pub_tool_basics.h"      /* Addr, SizeT */
#include "pub_tool_debuginfo.h"   /* VG_(get_objname)() */
#include "pub_tool_libcassert.h"  /* tl_assert() */
#include "pub_tool_libcbase.h"    /* VG_(memset) */
#include "pub_tool_libcprint.h"   /* VG_(printf) */
#include "pub_tool_machine.h"     /* VG_(get_IP)() */
#include "pub_tool_mallocfree.h"  /* VG_(malloc), VG_(free) */


/* Local function declarations. */

static void bm2_merge(struct bitmap2* const bm2l,
                      const struct bitmap2* const bm2r);
static void bm2_print(const struct bitmap2* const bm2);


/* Local variables. */

static OSet* s_bm2_set_template;
static ULong s_bitmap_creation_count;
static ULong s_bitmap_merge_count;
static ULong s_bitmap2_merge_count;


/* Function definitions. */

void DRD_(bm_module_init)(void)
{
   tl_assert(!s_bm2_set_template);
   s_bm2_set_template
      = VG_(OSetGen_Create_With_Pool)(0, 0, VG_(malloc), "drd.bitmap.bn.2",
                                      VG_(free), 512, sizeof(struct bitmap2));
}

void DRD_(bm_module_cleanup)(void)
{
   tl_assert(s_bm2_set_template);
   VG_(OSetGen_Destroy)(s_bm2_set_template);
   s_bm2_set_template = NULL;
}

struct bitmap* DRD_(bm_new)()
{
   struct bitmap* bm;

   /* If this assert fails, fix the definition of BITS_PER_BITS_PER_UWORD */
   /* in drd_bitmap.h.                                                    */
   tl_assert((1 << BITS_PER_BITS_PER_UWORD) == BITS_PER_UWORD);

   bm = VG_(malloc)("drd.bitmap.bn.1", sizeof(*bm));
   DRD_(bm_init)(bm);

   return bm;
}

void DRD_(bm_delete)(struct bitmap* const bm)
{
   tl_assert(bm);

   DRD_(bm_cleanup)(bm);
   VG_(free)(bm);
}

/** Initialize *bm. */
void DRD_(bm_init)(struct bitmap* const bm)
{
   unsigned i;

   tl_assert(bm);
   /*
    * Cache initialization. a1 is initialized with a value that never can
    * match any valid address: the upper (ADDR_LSB_BITS + ADDR_IGNORED_BITS)
    * bits of a1 are always zero for a valid cache entry.
    */
   for (i = 0; i < DRD_BITMAP_N_CACHE_ELEM; i++)
   {
      bm->cache[i].a1  = ~(UWord)1;
      bm->cache[i].bm2 = 0;
   }
   bm->oset = VG_(OSetGen_EmptyClone)(s_bm2_set_template);

   s_bitmap_creation_count++;
}

/** Free the memory allocated by DRD_(bm_init)(). */
void DRD_(bm_cleanup)(struct bitmap* const bm)
{
   VG_(OSetGen_Destroy)(bm->oset);
}

/**
 * Record an access of type access_type at addresses a .. a + size - 1 in
 * bitmap bm.
 *
 * @note The current implementation of bm_access_range does not work for the
 * highest addresses in the address range. At least on Linux this is
 * not a problem since the upper part of the address space is reserved
 * for the kernel.
 */
void DRD_(bm_access_range)(struct bitmap* const bm,
                           const Addr a1, const Addr a2,
                           const BmAccessTypeT access_type)
{
   tl_assert(access_type == eLoad || access_type == eStore);

   if (access_type == eLoad)
      return DRD_(bm_access_range_load)(bm, a1, a2);
   else
      return DRD_(bm_access_range_store)(bm, a1, a2);
}

void DRD_(bm_access_range_load)(struct bitmap* const bm, Addr a1, Addr a2)
{
   Addr b, b_next;

   tl_assert(bm);
   tl_assert(a1 <= a2);
   tl_assert(a2 < first_address_with_higher_msb(a2));
   tl_assert(a1 == first_address_with_same_lsb(a1));
   tl_assert(a2 == first_address_with_same_lsb(a2));

   for (b = a1; b < a2; b = b_next)
   {
      Addr b_start;
      Addr b_end;
      struct bitmap2* bm2;
      UWord b0;

      b_next = first_address_with_higher_msb(b);
      if (b_next > a2)
      {
         b_next = a2;
      }

      bm2 = bm2_lookup_or_insert_exclusive(bm, address_msb(b));
      tl_assert(bm2);

      if (make_address(bm2->addr, 0) < a1)
         b_start = a1;
      else
         if (make_address(bm2->addr, 0) < a2)
            b_start = make_address(bm2->addr, 0);
         else
            break;

      if (make_address(bm2->addr + 1, 0) < a2)
         b_end = make_address(bm2->addr + 1, 0);
      else
         b_end = a2;

      tl_assert(a1 <= b_start && b_start < b_end && b_end && b_end <= a2);
      tl_assert(address_msb(b_start) == address_msb(b_end - 1));
      tl_assert(address_lsb(b_start) <= address_lsb(b_end - 1));

      if (address_lsb(b_start) == 0 && address_lsb(b_end) == 0)
      {
         unsigned k;

         for (k = 0; k < BITMAP1_UWORD_COUNT; k++)
         {
            bm2->bm1.bm0_r[k] = ~(UWord)0;
         }
      }
      else
      {
         for (b0 = address_lsb(b_start); b0 <= address_lsb(b_end - 1); b0++)
         {
            bm0_set(bm2->bm1.bm0_r, b0);
         }
      }
   }
}

void DRD_(bm_access_load_1)(struct bitmap* const bm, const Addr a1)
{
   bm_access_aligned_load(bm, a1, 1);
}

void DRD_(bm_access_load_2)(struct bitmap* const bm, const Addr a1)
{
   if ((a1 & 1) == 0)
      bm_access_aligned_load(bm, a1, 2);
   else
      DRD_(bm_access_range)(bm, a1, a1 + 2, eLoad);
}

void DRD_(bm_access_load_4)(struct bitmap* const bm, const Addr a1)
{
   if ((a1 & 3) == 0)
      bm_access_aligned_load(bm, a1, 4);
   else
      DRD_(bm_access_range)(bm, a1, a1 + 4, eLoad);
}

void DRD_(bm_access_load_8)(struct bitmap* const bm, const Addr a1)
{
   if ((a1 & 7) == 0)
      bm_access_aligned_load(bm, a1, 8);
   else if ((a1 & 3) == 0)
   {
      bm_access_aligned_load(bm, a1 + 0, 4);
      bm_access_aligned_load(bm, a1 + 4, 4);
   }
   else
      DRD_(bm_access_range)(bm, a1, a1 + 8, eLoad);
}

void DRD_(bm_access_range_store)(struct bitmap* const bm,
                                 const Addr a1, const Addr a2)
{
   Addr b, b_next;

   tl_assert(bm);
   tl_assert(a1 <= a2);
   tl_assert(a2 < first_address_with_higher_msb(a2));
   tl_assert(a1 == first_address_with_same_lsb(a1));
   tl_assert(a2 == first_address_with_same_lsb(a2));

   for (b = a1; b < a2; b = b_next)
   {
      Addr b_start;
      Addr b_end;
      struct bitmap2* bm2;
      UWord b0;

      b_next = first_address_with_higher_msb(b);
      if (b_next > a2)
      {
         b_next = a2;
      }

      bm2 = bm2_lookup_or_insert_exclusive(bm, address_msb(b));
      tl_assert(bm2);

      if (make_address(bm2->addr, 0) < a1)
         b_start = a1;
      else
         if (make_address(bm2->addr, 0) < a2)
            b_start = make_address(bm2->addr, 0);
         else
            break;

      if (make_address(bm2->addr + 1, 0) < a2)
         b_end = make_address(bm2->addr + 1, 0);
      else
         b_end = a2;

      tl_assert(a1 <= b_start && b_start < b_end && b_end && b_end <= a2);
      tl_assert(address_msb(b_start) == address_msb(b_end - 1));
      tl_assert(address_lsb(b_start) <= address_lsb(b_end - 1));

      if (address_lsb(b_start) == 0 && address_lsb(b_end) == 0)
      {
         unsigned k;

         for (k = 0; k < BITMAP1_UWORD_COUNT; k++)
         {
            bm2->bm1.bm0_w[k] = ~(UWord)0;
         }
      }
      else
      {
         for (b0 = address_lsb(b_start); b0 <= address_lsb(b_end - 1); b0++)
         {
            bm0_set(bm2->bm1.bm0_w, b0);
         }
      }
   }
}

void DRD_(bm_access_store_1)(struct bitmap* const bm, const Addr a1)
{
   bm_access_aligned_store(bm, a1, 1);
}

void DRD_(bm_access_store_2)(struct bitmap* const bm, const Addr a1)
{
   if ((a1 & 1) == 0)
      bm_access_aligned_store(bm, a1, 2);
   else
      DRD_(bm_access_range)(bm, a1, a1 + 2, eStore);
}

void DRD_(bm_access_store_4)(struct bitmap* const bm, const Addr a1)
{
   if ((a1 & 3) == 0)
      bm_access_aligned_store(bm, a1, 4);
   else
      DRD_(bm_access_range)(bm, a1, a1 + 4, eStore);
}

void DRD_(bm_access_store_8)(struct bitmap* const bm, const Addr a1)
{
   if ((a1 & 7) == 0)
      bm_access_aligned_store(bm, a1, 8);
   else if ((a1 & 3) == 0)
   {
      bm_access_aligned_store(bm, a1 + 0, 4);
      bm_access_aligned_store(bm, a1 + 4, 4);
   }
   else
      DRD_(bm_access_range)(bm, a1, a1 + 8, eStore);
}

Bool DRD_(bm_has)(struct bitmap* const bm, const Addr a1, const Addr a2,
                  const BmAccessTypeT access_type)
{
   tl_assert(access_type == eLoad || access_type == eStore);

   if (access_type == eLoad)
      return DRD_(bm_has_any_load)(bm, a1, a2);
   else
      return DRD_(bm_has_any_store)(bm, a1, a2);
}

Bool DRD_(bm_has_any_load_g)(struct bitmap* const bm)
{
   struct bitmap2* bm2;

   tl_assert(bm);

   VG_(OSetGen_ResetIter)(bm->oset);
   for ( ; (bm2 = VG_(OSetGen_Next)(bm->oset)) != NULL; ) {
      Addr b_start;
      Addr b_end;
      UWord b0;
      const struct bitmap1* const p1 = &bm2->bm1;

      b_start = make_address(bm2->addr, 0);
      b_end = make_address(bm2->addr + 1, 0);

      for (b0 = address_lsb(b_start); b0 <= address_lsb(b_end - 1); b0++)
         if (bm0_is_set(p1->bm0_r, b0))
            return True;
   }
   return False;
}

Bool
DRD_(bm_has_any_load)(struct bitmap* const bm, const Addr a1, const Addr a2)
{
   Addr b, b_next;

   tl_assert(bm);

   for (b = a1; b < a2; b = b_next)
   {
      const struct bitmap2* bm2 = bm2_lookup(bm, address_msb(b));

      b_next = first_address_with_higher_msb(b);
      if (b_next > a2)
      {
         b_next = a2;
      }

      if (bm2)
      {
         Addr b_start;
         Addr b_end;
         UWord b0;
         const struct bitmap1* const p1 = &bm2->bm1;

         if (make_address(bm2->addr, 0) < a1)
            b_start = a1;
         else
            if (make_address(bm2->addr, 0) < a2)
               b_start = make_address(bm2->addr, 0);
            else
               break;
         tl_assert(a1 <= b_start && b_start <= a2);

         if (make_address(bm2->addr + 1, 0) < a2)
            b_end = make_address(bm2->addr + 1, 0);
         else
            b_end = a2;
         tl_assert(a1 <= b_end && b_end <= a2);
         tl_assert(b_start < b_end);
         tl_assert(address_lsb(b_start) <= address_lsb(b_end - 1));

         for (b0 = address_lsb(b_start); b0 <= address_lsb(b_end - 1); b0++)
         {
            if (bm0_is_set(p1->bm0_r, b0))
            {
               return True;
            }
         }
      }
   }
   return 0;
}

Bool DRD_(bm_has_any_store)(struct bitmap* const bm,
                            const Addr a1, const Addr a2)
{
   Addr b, b_next;

   tl_assert(bm);

   for (b = a1; b < a2; b = b_next)
   {
      const struct bitmap2* bm2 = bm2_lookup(bm, address_msb(b));

      b_next = first_address_with_higher_msb(b);
      if (b_next > a2)
      {
         b_next = a2;
      }

      if (bm2)
      {
         Addr b_start;
         Addr b_end;
         UWord b0;
         const struct bitmap1* const p1 = &bm2->bm1;

         if (make_address(bm2->addr, 0) < a1)
            b_start = a1;
         else
            if (make_address(bm2->addr, 0) < a2)
               b_start = make_address(bm2->addr, 0);
            else
               break;
         tl_assert(a1 <= b_start && b_start <= a2);

         if (make_address(bm2->addr + 1, 0) < a2)
            b_end = make_address(bm2->addr + 1, 0);
         else
            b_end = a2;
         tl_assert(a1 <= b_end && b_end <= a2);
         tl_assert(b_start < b_end);
         tl_assert(address_lsb(b_start) <= address_lsb(b_end - 1));

         for (b0 = address_lsb(b_start); b0 <= address_lsb(b_end - 1); b0++)
         {
            if (bm0_is_set(p1->bm0_w, b0))
            {
               return True;
            }
         }
      }
   }
   return 0;
}

/* Return True if there is a read access, write access or both   */
/* to any of the addresses in the range [ a1, a2 [ in bitmap bm. */
Bool DRD_(bm_has_any_access)(struct bitmap* const bm,
                             const Addr a1, const Addr a2)
{
   Addr b, b_next;

   tl_assert(bm);

   for (b = a1; b < a2; b = b_next)
   {
      const struct bitmap2* bm2 = bm2_lookup(bm, address_msb(b));

      b_next = first_address_with_higher_msb(b);
      if (b_next > a2)
      {
         b_next = a2;
      }

      if (bm2)
      {
         Addr b_start;
         Addr b_end;
         UWord b0;
         const struct bitmap1* const p1 = &bm2->bm1;

         if (make_address(bm2->addr, 0) < a1)
            b_start = a1;
         else
            if (make_address(bm2->addr, 0) < a2)
               b_start = make_address(bm2->addr, 0);
            else
               break;
         tl_assert(a1 <= b_start && b_start <= a2);

         if (make_address(bm2->addr + 1, 0) < a2)
            b_end = make_address(bm2->addr + 1, 0);
         else
            b_end = a2;
         tl_assert(a1 <= b_end && b_end <= a2);
         tl_assert(b_start < b_end);
         tl_assert(address_lsb(b_start) <= address_lsb(b_end - 1));

         for (b0 = address_lsb(b_start); b0 <= address_lsb(b_end - 1); b0++)
         {
            /*
             * Note: the statement below uses a binary or instead of a logical
             * or on purpose.
             */
            if (bm0_is_set(p1->bm0_r, b0) | bm0_is_set(p1->bm0_w, b0))
            {
               return True;
            }
         }
      }
   }
   return False;
}

/**
 * Report whether an access of type access_type at address a is recorded in
 * bitmap bm.
 */
Bool DRD_(bm_has_1)(struct bitmap* const bm,
                    const Addr a, const BmAccessTypeT access_type)
{
   const struct bitmap2* p2;
   const struct bitmap1* p1;
   const UWord* p0;
   const UWord a0 = address_lsb(a);

   tl_assert(bm);

   p2 = bm2_lookup(bm, address_msb(a));
   if (p2)
   {
      p1 = &p2->bm1;
      p0 = (access_type == eLoad) ? p1->bm0_r : p1->bm0_w;
      return bm0_is_set(p0, a0) ? True : False;
   }
   return False;
}

void DRD_(bm_clear)(struct bitmap* const bm, Addr a1, Addr a2)
{
   Addr b, b_next;

   tl_assert(bm);
   tl_assert(a1);
   tl_assert(a1 <= a2);
   tl_assert(a1 == first_address_with_same_lsb(a1));
   tl_assert(a2 == first_address_with_same_lsb(a2));

   for (b = a1; b < a2; b = b_next)
   {
      struct bitmap2* p2;
      Addr c;

#ifdef ENABLE_DRD_CONSISTENCY_CHECKS
      tl_assert(a1 <= b && b < a2);
#endif

      p2 = bm2_lookup_exclusive(bm, address_msb(b));

      b_next = first_address_with_higher_msb(b);
      if (b_next > a2)
      {
         b_next = a2;
      }

      if (p2 == 0)
         continue;

      c = b;
      /* If the first address in the bitmap that must be cleared does not */
      /* start on an UWord boundary, start clearing the first addresses.  */
      if (uword_lsb(address_lsb(c)))
      {
         Addr c_next = first_address_with_higher_uword_msb(c);
         if (c_next > b_next)
            c_next = b_next;
#ifdef ENABLE_DRD_CONSISTENCY_CHECKS
         tl_assert(a1 <= b && b <= c && c <= c_next && c_next <= b_next
                   && b_next <= a2);
#endif
         bm0_clear_range(p2->bm1.bm0_r, address_lsb(c), SCALED_SIZE(c_next - c));
         bm0_clear_range(p2->bm1.bm0_w, address_lsb(c), SCALED_SIZE(c_next - c));
         c = c_next;
      }
      /* If some UWords have to be cleared entirely, do this now. */
      if (uword_lsb(address_lsb(c)) == 0)
      {
         Addr c_next = first_address_with_same_uword_lsb(b_next);
#ifdef ENABLE_DRD_CONSISTENCY_CHECKS
         tl_assert(uword_lsb(address_lsb(c)) == 0);
         tl_assert(uword_lsb(address_lsb(c_next)) == 0);
         tl_assert(c_next <= b_next);
#endif
         if (c_next > c)
         {
            UWord idx = uword_msb(address_lsb(c));
            VG_(memset)(&p2->bm1.bm0_r[idx], 0, SCALED_SIZE((c_next - c) / 8));
            VG_(memset)(&p2->bm1.bm0_w[idx], 0, SCALED_SIZE((c_next - c) / 8));
            c = c_next;
         }
      }
      /* If the last address in the bitmap that must be cleared does not */
      /* fall on an UWord boundary, clear the last addresses.            */
#ifdef ENABLE_DRD_CONSISTENCY_CHECKS
      tl_assert(a1 <= b && b <= c && c <= b_next && b_next <= a2);
#endif
      bm0_clear_range(p2->bm1.bm0_r, address_lsb(c), SCALED_SIZE(b_next - c));
      bm0_clear_range(p2->bm1.bm0_w, address_lsb(c), SCALED_SIZE(b_next - c));
   }
}

/**
 * Clear all references to loads in bitmap bm starting at address a1 and
 * up to but not including address a2.
 */
void DRD_(bm_clear_load)(struct bitmap* const bm, Addr a1, Addr a2)
{
   Addr b, b_next;

   tl_assert(bm);
   tl_assert(a1);
   tl_assert(a1 <= a2);
   tl_assert(a1 == first_address_with_same_lsb(a1));
   tl_assert(a2 == first_address_with_same_lsb(a2));

   for (b = a1; b < a2; b = b_next)
   {
      struct bitmap2* p2;
      Addr c;

#ifdef ENABLE_DRD_CONSISTENCY_CHECKS
      tl_assert(a1 <= b && b < a2);
#endif

      p2 = bm2_lookup_exclusive(bm, address_msb(b));

      b_next = first_address_with_higher_msb(b);
      if (b_next > a2)
      {
         b_next = a2;
      }

      if (p2 == 0)
         continue;

      c = b;
      /* If the first address in the bitmap that must be cleared does not */
      /* start on an UWord boundary, start clearing the first addresses.  */
#ifdef ENABLE_DRD_CONSISTENCY_CHECKS
      tl_assert(a1 <= b && b <= c && c < b_next && b_next <= a2);
#endif
      if (uword_lsb(address_lsb(c)))
      {
         Addr c_next = first_address_with_higher_uword_msb(c);
         if (c_next > b_next)
            c_next = b_next;
#ifdef ENABLE_DRD_CONSISTENCY_CHECKS
         tl_assert(a1 <= b && b <= c && c < c_next && c_next <= b_next
                   && b_next <= a2);
#endif
         bm0_clear_range(p2->bm1.bm0_r, address_lsb(c), SCALED_SIZE(c_next - c));
         c = c_next;
      }
      /* If some UWords have to be cleared entirely, do this now. */
#ifdef ENABLE_DRD_CONSISTENCY_CHECKS
      tl_assert(a1 <= b && b <= c && c <= b_next && b_next <= a2);
#endif
      if (uword_lsb(address_lsb(c)) == 0)
      {
         Addr c_next = first_address_with_same_uword_lsb(b_next);
#ifdef ENABLE_DRD_CONSISTENCY_CHECKS
         tl_assert(uword_lsb(address_lsb(c)) == 0);
         tl_assert(uword_lsb(address_lsb(c_next)) == 0);
         tl_assert(a1 <= b && b <= c && c <= c_next && c_next <= b_next
                   && b_next <= a2);
#endif
         if (c_next > c)
         {
            UWord idx = uword_msb(address_lsb(c));
            VG_(memset)(&p2->bm1.bm0_r[idx], 0, SCALED_SIZE((c_next - c) / 8));
            c = c_next;
         }
      }
      /* If the last address in the bitmap that must be cleared does not */
      /* fall on an UWord boundary, clear the last addresses.            */
#ifdef ENABLE_DRD_CONSISTENCY_CHECKS
      tl_assert(a1 <= b && b <= c && c <= b_next && b_next <= a2);
#endif
      bm0_clear_range(p2->bm1.bm0_r, address_lsb(c), SCALED_SIZE(b_next - c));
   }
}

/**
 * Clear all references to stores in bitmap bm starting at address a1 and
 * up to but not including address a2.
 */
void DRD_(bm_clear_store)(struct bitmap* const bm,
                          const Addr a1, const Addr a2)
{
   Addr b, b_next;

   tl_assert(bm);
   tl_assert(a1);
   tl_assert(a1 <= a2);
   tl_assert(a1 == first_address_with_same_lsb(a1));
   tl_assert(a2 == first_address_with_same_lsb(a2));

   for (b = a1; b < a2; b = b_next)
   {
      struct bitmap2* p2;
      Addr c;

#ifdef ENABLE_DRD_CONSISTENCY_CHECKS
      tl_assert(a1 <= b && b < a2);
#endif

      p2 = bm2_lookup_exclusive(bm, address_msb(b));

      b_next = first_address_with_higher_msb(b);
      if (b_next > a2)
      {
         b_next = a2;
      }

      if (p2 == 0)
         continue;

      c = b;
      /* If the first address in the bitmap that must be cleared does not */
      /* start on an UWord boundary, start clearing the first addresses.  */
#ifdef ENABLE_DRD_CONSISTENCY_CHECKS
      tl_assert(a1 <= b && b <= c && c < b_next && b_next <= a2);
#endif
      if (uword_lsb(address_lsb(c)))
      {
         Addr c_next = first_address_with_higher_uword_msb(c);
         if (c_next > b_next)
            c_next = b_next;
#ifdef ENABLE_DRD_CONSISTENCY_CHECKS
         tl_assert(a1 <= b && b <= c && c < c_next && c_next <= b_next
                   && b_next <= a2);
#endif
         bm0_clear_range(p2->bm1.bm0_w, address_lsb(c), SCALED_SIZE(c_next - c));
         c = c_next;
      }
      /* If some UWords have to be cleared entirely, do this now. */
#ifdef ENABLE_DRD_CONSISTENCY_CHECKS
      tl_assert(a1 <= b && b <= c && c <= b_next && b_next <= a2);
#endif
      if (uword_lsb(address_lsb(c)) == 0)
      {
         Addr c_next = first_address_with_same_uword_lsb(b_next);
#ifdef ENABLE_DRD_CONSISTENCY_CHECKS
         tl_assert(uword_lsb(address_lsb(c)) == 0);
         tl_assert(uword_lsb(address_lsb(c_next)) == 0);
         tl_assert(a1 <= b && b <= c && c <= c_next && c_next <= b_next
                   && b_next <= a2);
#endif
         if (c_next > c)
         {
            UWord idx = uword_msb(address_lsb(c));
            VG_(memset)(&p2->bm1.bm0_w[idx], 0, SCALED_SIZE((c_next - c) / 8));
            c = c_next;
         }
      }
      /* If the last address in the bitmap that must be cleared does not */
      /* fall on an UWord boundary, clear the last addresses.            */
#ifdef ENABLE_DRD_CONSISTENCY_CHECKS
      tl_assert(a1 <= b && b <= c && c <= b_next && b_next <= a2);
#endif
      bm0_clear_range(p2->bm1.bm0_w, address_lsb(c), SCALED_SIZE(b_next - c));
   }
}

/**
 * Clear bitmap bm starting at address a1 and up to but not including address
 * a2. Return True if and only if any of the addresses was set before
 * clearing.
 */
Bool DRD_(bm_test_and_clear)(struct bitmap* const bm,
                             const Addr a1, const Addr a2)
{
   Bool result;

   result = DRD_(bm_has_any_access)(bm, a1, a2) != 0;
   DRD_(bm_clear)(bm, a1, a2);
   return result;
}

Bool DRD_(bm_has_conflict_with)(struct bitmap* const bm,
                                const Addr a1, const Addr a2,
                                const BmAccessTypeT access_type)
{
   Addr b, b_next;

   tl_assert(bm);

   for (b = a1; b < a2; b = b_next)
   {
      const struct bitmap2* bm2 = bm2_lookup(bm, address_msb(b));

      b_next = first_address_with_higher_msb(b);
      if (b_next > a2)
      {
         b_next = a2;
      }

      if (bm2)
      {
         Addr b_start;
         Addr b_end;
         UWord b0;
         const struct bitmap1* const p1 = &bm2->bm1;

         if (make_address(bm2->addr, 0) < a1)
            b_start = a1;
         else
            if (make_address(bm2->addr, 0) < a2)
               b_start = make_address(bm2->addr, 0);
            else
               break;
         tl_assert(a1 <= b_start && b_start <= a2);

         if (make_address(bm2->addr + 1, 0) < a2)
            b_end = make_address(bm2->addr + 1, 0);
         else
            b_end = a2;
         tl_assert(a1 <= b_end && b_end <= a2);
         tl_assert(b_start < b_end);
         tl_assert(address_lsb(b_start) <= address_lsb(b_end - 1));

         for (b0 = address_lsb(b_start); b0 <= address_lsb(b_end - 1); b0++)
         {
            if (access_type == eLoad)
            {
               if (bm0_is_set(p1->bm0_w, b0))
               {
                  return True;
               }
            }
            else
            {
               tl_assert(access_type == eStore);
               if (bm0_is_set(p1->bm0_r, b0)
                   | bm0_is_set(p1->bm0_w, b0))
               {
                  return True;
               }
            }
         }
      }
   }
   return False;
}

Bool DRD_(bm_load_has_conflict_with)(struct bitmap* const bm,
                                     const Addr a1, const Addr a2)
{
   return DRD_(bm_has_conflict_with)(bm, a1, a2, eLoad);
}

Bool DRD_(bm_load_1_has_conflict_with)(struct bitmap* const bm, const Addr a1)
{
   return bm_aligned_load_has_conflict_with(bm, a1, 1);
}

Bool DRD_(bm_load_2_has_conflict_with)(struct bitmap* const bm, const Addr a1)
{
   if ((a1 & 1) == 0)
      return bm_aligned_load_has_conflict_with(bm, a1, 2);
   else
      return DRD_(bm_has_conflict_with)(bm, a1, a1 + 2, eLoad);
}

Bool DRD_(bm_load_4_has_conflict_with)(struct bitmap* const bm, const Addr a1)
{
   if ((a1 & 3) == 0)
      return bm_aligned_load_has_conflict_with(bm, a1, 4);
   else
      return DRD_(bm_has_conflict_with)(bm, a1, a1 + 4, eLoad);
}

Bool DRD_(bm_load_8_has_conflict_with)(struct bitmap* const bm, const Addr a1)
{
   if ((a1 & 7) == 0)
      return bm_aligned_load_has_conflict_with(bm, a1, 8);
   else
      return DRD_(bm_has_conflict_with)(bm, a1, a1 + 8, eLoad);
}

Bool DRD_(bm_store_1_has_conflict_with)(struct bitmap* const bm, const Addr a1)
{
   return bm_aligned_store_has_conflict_with(bm, a1, 1);
}

Bool DRD_(bm_store_2_has_conflict_with)(struct bitmap* const bm, const Addr a1)
{
   if ((a1 & 1) == 0)
      return bm_aligned_store_has_conflict_with(bm, a1, 2);
   else
      return DRD_(bm_has_conflict_with)(bm, a1, a1 + 2, eStore);
}

Bool DRD_(bm_store_4_has_conflict_with)(struct bitmap* const bm, const Addr a1)
{
   if ((a1 & 3) == 0)
      return bm_aligned_store_has_conflict_with(bm, a1, 4);
   else
      return DRD_(bm_has_conflict_with)(bm, a1, a1 + 4, eStore);
}

Bool DRD_(bm_store_8_has_conflict_with)(struct bitmap* const bm, const Addr a1)
{
   if ((a1 & 7) == 0)
      return bm_aligned_store_has_conflict_with(bm, a1, 8);
   else
      return DRD_(bm_has_conflict_with)(bm, a1, a1 + 8, eStore);
}

Bool DRD_(bm_store_has_conflict_with)(struct bitmap* const bm,
                                      const Addr a1, const Addr a2)
{
   return DRD_(bm_has_conflict_with)(bm, a1, a2, eStore);
}

/**
 * Return True if the two bitmaps *lhs and *rhs are identical, and false
 * if not.
 */
Bool DRD_(bm_equal)(struct bitmap* const lhs, struct bitmap* const rhs)
{
   struct bitmap2* bm2l;
   struct bitmap2* bm2r;

   /* It's not possible to have two independent iterators over the same OSet, */
   /* so complain if lhs == rhs.                                              */
   tl_assert(lhs != rhs);

   VG_(OSetGen_ResetIter)(lhs->oset);
   VG_(OSetGen_ResetIter)(rhs->oset);

   for ( ; (bm2l = VG_(OSetGen_Next)(lhs->oset)) != 0; )
   {
      while (bm2l
             && ! DRD_(bm_has_any_access)(lhs,
                                          make_address(bm2l->addr, 0),
                                          make_address(bm2l->addr + 1, 0)))
      {
         bm2l = VG_(OSetGen_Next)(lhs->oset);
      }
      if (bm2l == 0)
         break;
      tl_assert(bm2l);

      do
      {
         bm2r = VG_(OSetGen_Next)(rhs->oset);
         if (bm2r == 0)
            return False;
      }
      while (! DRD_(bm_has_any_access)(rhs,
                                       make_address(bm2r->addr, 0),
                                       make_address(bm2r->addr + 1, 0)));

      tl_assert(bm2r);
      tl_assert(DRD_(bm_has_any_access)(rhs,
                                        make_address(bm2r->addr, 0),
                                        make_address(bm2r->addr + 1, 0)));

      if (bm2l != bm2r
          && (bm2l->addr != bm2r->addr
              || VG_(memcmp)(&bm2l->bm1, &bm2r->bm1, sizeof(bm2l->bm1)) != 0))
      {
         return False;
      }
   }

   do
   {
      bm2r = VG_(OSetGen_Next)(rhs->oset);
   } while (bm2r && ! DRD_(bm_has_any_access)(rhs,
                                              make_address(bm2r->addr, 0),
                                              make_address(bm2r->addr + 1, 0)));
   if (bm2r)
   {
      tl_assert(DRD_(bm_has_any_access)(rhs,
                                        make_address(bm2r->addr, 0),
                                        make_address(bm2r->addr + 1, 0)));
      return False;
   }
   return True;
}

void DRD_(bm_swap)(struct bitmap* const bm1, struct bitmap* const bm2)
{
   OSet* const tmp = bm1->oset;
   bm1->oset = bm2->oset;
   bm2->oset = tmp;
}

/** Merge bitmaps *lhs and *rhs into *lhs. */
void DRD_(bm_merge2)(struct bitmap* const lhs, struct bitmap* const rhs)
{
   struct bitmap2* bm2l;
   struct bitmap2* bm2r;

   /*
    * It's not possible to have two independent iterators over the same OSet,
    * so complain if lhs == rhs.
    */
   tl_assert(lhs != rhs);

   s_bitmap_merge_count++;

   VG_(OSetGen_ResetIter)(rhs->oset);

   for ( ; (bm2r = VG_(OSetGen_Next)(rhs->oset)) != 0; )
   {
      bm2l = VG_(OSetGen_Lookup)(lhs->oset, &bm2r->addr);
      if (bm2l)
      {
         tl_assert(bm2l != bm2r);
         bm2_merge(bm2l, bm2r);
      }
      else
      {
         bm2_insert_copy(lhs, bm2r);
      }
   }
}

/** Clear bitmap2::recalc. */
void DRD_(bm_unmark)(struct bitmap* bm)
{
   struct bitmap2* bm2;

   for (VG_(OSetGen_ResetIter)(bm->oset);
        (bm2 = VG_(OSetGen_Next)(bm->oset)) != 0;
        )
   {
      bm2->recalc = False;
   }
}

/**
 * Report whether bitmap2::recalc has been set for the second level bitmap
 * corresponding to address a.
 */
Bool DRD_(bm_is_marked)(struct bitmap* bm, const Addr a)
{
   const struct bitmap2* bm2;

   bm2 = bm2_lookup(bm, a);
   return bm2 && bm2->recalc;
}

/**
 * Set bitmap2::recalc in bml for each second level bitmap in bmr that contains
 * at least one access.
 *
 * @note Any new second-level bitmaps inserted in bml by this function are
 *       uninitialized.
 */
void DRD_(bm_mark)(struct bitmap* bml, struct bitmap* bmr)
{
   struct bitmap2* bm2l;
   struct bitmap2* bm2r;

   for (VG_(OSetGen_ResetIter)(bmr->oset);
        (bm2r = VG_(OSetGen_Next)(bmr->oset)) != 0;
        )
   {
      bm2l = bm2_lookup_or_insert(bml, bm2r->addr);
      bm2l->recalc = True;
   }
}

/** Clear all second-level bitmaps for which bitmap2::recalc == True. */
void DRD_(bm_clear_marked)(struct bitmap* bm)
{
   struct bitmap2* bm2;

   for (VG_(OSetGen_ResetIter)(bm->oset);
        (bm2 = VG_(OSetGen_Next)(bm->oset)) != 0;
        )
   {
      if (bm2->recalc)
         bm2_clear(bm2);
   }
}

/** Merge the second level bitmaps from *rhs into *lhs for which recalc == True. */
void DRD_(bm_merge2_marked)(struct bitmap* const lhs, struct bitmap* const rhs)
{
   struct bitmap2* bm2l;
   struct bitmap2* bm2r;

   /*
    * It's not possible to have two independent iterators over the same OSet,
    * so complain if lhs == rhs.
    */
   tl_assert(lhs != rhs);

   s_bitmap_merge_count++;

   VG_(OSetGen_ResetIter)(rhs->oset);

   for ( ; (bm2r = VG_(OSetGen_Next)(rhs->oset)) != 0; )
   {
      bm2l = VG_(OSetGen_Lookup)(lhs->oset, &bm2r->addr);
      if (bm2l && bm2l->recalc)
      {
         tl_assert(bm2l != bm2r);
         bm2_merge(bm2l, bm2r);
      }
   }
}

/** Remove all marked second-level bitmaps that do not contain any access. */
void DRD_(bm_remove_cleared_marked)(struct bitmap* bm)
{
   struct bitmap2* bm2;

   VG_(OSetGen_ResetIter)(bm->oset);
   for ( ; (bm2 = VG_(OSetGen_Next)(bm->oset)) != 0; )
   {
      const UWord a1 = bm2->addr;
      if (bm2->recalc
          && ! DRD_(bm_has_any_access(bm, make_address(a1, 0),
                                      make_address(a1 + 1, 0))))
      {
         bm2_remove(bm, a1);
         VG_(OSetGen_ResetIterAt)(bm->oset, &a1);
      }
   }
}

/**
 * Report whether there are any RW / WR / WW patterns in lhs and rhs.
 * @param lhs First bitmap.
 * @param rhs Bitmap to be compared with lhs.
 * @return !=0 if there are data races, == 0 if there are none.
 */
int DRD_(bm_has_races)(struct bitmap* const lhs, struct bitmap* const rhs)
{
   VG_(OSetGen_ResetIter)(lhs->oset);
   VG_(OSetGen_ResetIter)(rhs->oset);

   for (;;)
   {
      const struct bitmap2* bm2l;
      const struct bitmap2* bm2r;
      const struct bitmap1* bm1l;
      const struct bitmap1* bm1r;
      unsigned k;

      bm2l = VG_(OSetGen_Next)(lhs->oset);
      bm2r = VG_(OSetGen_Next)(rhs->oset);
      while (bm2l && bm2r && bm2l->addr != bm2r->addr)
      {
         if (bm2l->addr < bm2r->addr)
            bm2l = VG_(OSetGen_Next)(lhs->oset);
         else
            bm2r = VG_(OSetGen_Next)(rhs->oset);
      }
      if (bm2l == 0 || bm2r == 0)
         break;

      bm1l = &bm2l->bm1;
      bm1r = &bm2r->bm1;

      for (k = 0; k < BITMAP1_UWORD_COUNT; k++)
      {
         unsigned b;
         for (b = 0; b < BITS_PER_UWORD; b++)
         {
            UWord const access_mask
               = ((bm1l->bm0_r[k] & bm0_mask(b)) ? LHS_R : 0)
               | ((bm1l->bm0_w[k] & bm0_mask(b)) ? LHS_W : 0)
               | ((bm1r->bm0_r[k] & bm0_mask(b)) ? RHS_R : 0)
               | ((bm1r->bm0_w[k] & bm0_mask(b)) ? RHS_W : 0);
            Addr const a = make_address(bm2l->addr, k * BITS_PER_UWORD | b);
            if (HAS_RACE(access_mask) && ! DRD_(is_suppressed)(a, a + 1))
            {
               return 1;
            }
         }
      }
   }
   return 0;
}

void DRD_(bm_print)(struct bitmap* const bm)
{
   struct bitmap2* bm2;

   for (VG_(OSetGen_ResetIter)(bm->oset);
        (bm2 = VG_(OSetGen_Next)(bm->oset)) != 0;
        )
   {
      bm2_print(bm2);
   }
}

static void bm2_print(const struct bitmap2* const bm2)
{
   const struct bitmap1* bm1;
   Addr a;

   tl_assert(bm2);

   bm1 = &bm2->bm1;
   for (a = make_address(bm2->addr, 0);
        a <= make_address(bm2->addr + 1, 0) - 1;
        a++)
   {
      const Bool r = bm0_is_set(bm1->bm0_r, address_lsb(a)) != 0;
      const Bool w = bm0_is_set(bm1->bm0_w, address_lsb(a)) != 0;
      if (r || w)
      {
         VG_(printf)("0x%08lx %c %c\n",
                     a,
                     w ? 'W' : ' ',
                     r ? 'R' : ' ');
      }
   }
}

ULong DRD_(bm_get_bitmap_creation_count)(void)
{
   return s_bitmap_creation_count;
}

ULong DRD_(bm_get_bitmap2_creation_count)(void)
{
   return s_bitmap2_creation_count;
}

ULong DRD_(bm_get_bitmap2_merge_count)(void)
{
   return s_bitmap2_merge_count;
}

/** Compute *bm2l |= *bm2r. */
static
void bm2_merge(struct bitmap2* const bm2l, const struct bitmap2* const bm2r)
{
   unsigned k;

   tl_assert(bm2l);
   tl_assert(bm2r);
   tl_assert(bm2l->addr == bm2r->addr);

   s_bitmap2_merge_count++;

   for (k = 0; k < BITMAP1_UWORD_COUNT; k++)
   {
      bm2l->bm1.bm0_r[k] |= bm2r->bm1.bm0_r[k];
   }
   for (k = 0; k < BITMAP1_UWORD_COUNT; k++)
   {
      bm2l->bm1.bm0_w[k] |= bm2r->bm1.bm0_w[k];
   }
}