/*
 * kmp_lock.cpp -- lock-related functions
 * $Revision: 43389 $
 * $Date: 2014-08-11 10:54:01 -0500 (Mon, 11 Aug 2014) $
 */


//===----------------------------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.txt for details.
//
//===----------------------------------------------------------------------===//


#include <stddef.h>

#include "kmp.h"
#include "kmp_itt.h"
#include "kmp_i18n.h"
#include "kmp_lock.h"
#include "kmp_io.h"

#if KMP_OS_LINUX && (KMP_ARCH_X86 || KMP_ARCH_X86_64 || KMP_ARCH_ARM || KMP_ARCH_AARCH64)
# include <unistd.h>
# include <sys/syscall.h>
// We should really include <futex.h>, but that causes compatibility problems on different
// Linux* OS distributions that either require that you include (or break when you try to include)
// <pci/types.h>.
// Since all we need is the two macros below (which are part of the kernel ABI, so can't change)
// we just define the constants here and don't include <futex.h>
# ifndef FUTEX_WAIT
#  define FUTEX_WAIT    0
# endif
# ifndef FUTEX_WAKE
#  define FUTEX_WAKE    1
# endif
#endif

/* Implement spin locks for internal library use.             */
/* The algorithm implemented is Lamport's bakery lock [1974]. */

void
__kmp_validate_locks( void )
{
    int i;
    kmp_uint32  x, y;

    /* Check to make sure unsigned arithmetic does wraps properly */
    x = ~((kmp_uint32) 0) - 2;
    y = x - 2;

    for (i = 0; i < 8; ++i, ++x, ++y) {
        kmp_uint32 z = (x - y);
        KMP_ASSERT( z == 2 );
    }

    KMP_ASSERT( offsetof( kmp_base_queuing_lock, tail_id ) % 8 == 0 );
}


/* ------------------------------------------------------------------------ */
/* test and set locks */

//
// For the non-nested locks, we can only assume that the first 4 bytes were
// allocated, since gcc only allocates 4 bytes for omp_lock_t, and the Intel
// compiler only allocates a 4 byte pointer on IA-32 architecture.  On
// Windows* OS on Intel(R) 64, we can assume that all 8 bytes were allocated.
//
// gcc reserves >= 8 bytes for nested locks, so we can assume that the
// entire 8 bytes were allocated for nested locks on all 64-bit platforms.
//

static kmp_int32
__kmp_get_tas_lock_owner( kmp_tas_lock_t *lck )
{
    return TCR_4( lck->lk.poll ) - 1;
}

static inline bool
__kmp_is_tas_lock_nestable( kmp_tas_lock_t *lck )
{
    return lck->lk.depth_locked != -1;
}

__forceinline static void
__kmp_acquire_tas_lock_timed_template( kmp_tas_lock_t *lck, kmp_int32 gtid )
{
    KMP_MB();

#ifdef USE_LOCK_PROFILE
    kmp_uint32 curr = TCR_4( lck->lk.poll );
    if ( ( curr != 0 ) && ( curr != gtid + 1 ) )
        __kmp_printf( "LOCK CONTENTION: %p\n", lck );
    /* else __kmp_printf( "." );*/
#endif /* USE_LOCK_PROFILE */

    if ( ( lck->lk.poll == 0 )
      && KMP_COMPARE_AND_STORE_ACQ32( & ( lck->lk.poll ), 0, gtid + 1 ) ) {
        KMP_FSYNC_ACQUIRED(lck);
        return;
    }

    kmp_uint32 spins;
    KMP_FSYNC_PREPARE( lck );
    KMP_INIT_YIELD( spins );
    if ( TCR_4( __kmp_nth ) > ( __kmp_avail_proc ? __kmp_avail_proc :
      __kmp_xproc ) ) {
        KMP_YIELD( TRUE );
    }
    else {
        KMP_YIELD_SPIN( spins );
    }

    while ( ( lck->lk.poll != 0 ) ||
      ( ! KMP_COMPARE_AND_STORE_ACQ32( & ( lck->lk.poll ), 0, gtid + 1 ) ) ) {
        //
        // FIXME - use exponential backoff here
        //
        if ( TCR_4( __kmp_nth ) > ( __kmp_avail_proc ? __kmp_avail_proc :
          __kmp_xproc ) ) {
            KMP_YIELD( TRUE );
        }
        else {
            KMP_YIELD_SPIN( spins );
        }
    }
    KMP_FSYNC_ACQUIRED( lck );
}

void
__kmp_acquire_tas_lock( kmp_tas_lock_t *lck, kmp_int32 gtid )
{
    __kmp_acquire_tas_lock_timed_template( lck, gtid );
}

static void
__kmp_acquire_tas_lock_with_checks( kmp_tas_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_set_lock";
    if ( ( sizeof ( kmp_tas_lock_t ) <= OMP_LOCK_T_SIZE )
      && __kmp_is_tas_lock_nestable( lck ) ) {
        KMP_FATAL( LockNestableUsedAsSimple, func );
    }
    if ( ( gtid >= 0 ) && ( __kmp_get_tas_lock_owner( lck ) == gtid ) ) {
        KMP_FATAL( LockIsAlreadyOwned, func );
    }
    __kmp_acquire_tas_lock( lck, gtid );
}

int
__kmp_test_tas_lock( kmp_tas_lock_t *lck, kmp_int32 gtid )
{
    if ( ( lck->lk.poll == 0 )
      && KMP_COMPARE_AND_STORE_ACQ32( & ( lck->lk.poll ), 0, gtid + 1 ) ) {
        KMP_FSYNC_ACQUIRED( lck );
        return TRUE;
    }
    return FALSE;
}

static int
__kmp_test_tas_lock_with_checks( kmp_tas_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_test_lock";
    if ( ( sizeof ( kmp_tas_lock_t ) <= OMP_LOCK_T_SIZE )
      && __kmp_is_tas_lock_nestable( lck ) ) {
        KMP_FATAL( LockNestableUsedAsSimple, func );
    }
    return __kmp_test_tas_lock( lck, gtid );
}

void
__kmp_release_tas_lock( kmp_tas_lock_t *lck, kmp_int32 gtid )
{
    KMP_MB();       /* Flush all pending memory write invalidates.  */

    KMP_FSYNC_RELEASING(lck);
    KMP_ST_REL32( &(lck->lk.poll), 0 );

    KMP_MB();       /* Flush all pending memory write invalidates.  */

    KMP_YIELD( TCR_4( __kmp_nth ) > ( __kmp_avail_proc ? __kmp_avail_proc :
      __kmp_xproc ) );
}

static void
__kmp_release_tas_lock_with_checks( kmp_tas_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_unset_lock";
    KMP_MB();  /* in case another processor initialized lock */
    if ( ( sizeof ( kmp_tas_lock_t ) <= OMP_LOCK_T_SIZE )
      && __kmp_is_tas_lock_nestable( lck ) ) {
        KMP_FATAL( LockNestableUsedAsSimple, func );
    }
    if ( __kmp_get_tas_lock_owner( lck ) == -1 ) {
        KMP_FATAL( LockUnsettingFree, func );
    }
    if ( ( gtid >= 0 ) && ( __kmp_get_tas_lock_owner( lck ) >= 0 )
      && ( __kmp_get_tas_lock_owner( lck ) != gtid ) ) {
        KMP_FATAL( LockUnsettingSetByAnother, func );
    }
    __kmp_release_tas_lock( lck, gtid );
}

void
__kmp_init_tas_lock( kmp_tas_lock_t * lck )
{
    TCW_4( lck->lk.poll, 0 );
}

static void
__kmp_init_tas_lock_with_checks( kmp_tas_lock_t * lck )
{
    __kmp_init_tas_lock( lck );
}

void
__kmp_destroy_tas_lock( kmp_tas_lock_t *lck )
{
    lck->lk.poll = 0;
}

static void
__kmp_destroy_tas_lock_with_checks( kmp_tas_lock_t *lck )
{
    char const * const func = "omp_destroy_lock";
    if ( ( sizeof ( kmp_tas_lock_t ) <= OMP_LOCK_T_SIZE )
      && __kmp_is_tas_lock_nestable( lck ) ) {
        KMP_FATAL( LockNestableUsedAsSimple, func );
    }
    if ( __kmp_get_tas_lock_owner( lck ) != -1 ) {
        KMP_FATAL( LockStillOwned, func );
    }
    __kmp_destroy_tas_lock( lck );
}


//
// nested test and set locks
//

void
__kmp_acquire_nested_tas_lock( kmp_tas_lock_t *lck, kmp_int32 gtid )
{
    KMP_DEBUG_ASSERT( gtid >= 0 );

    if ( __kmp_get_tas_lock_owner( lck ) == gtid ) {
        lck->lk.depth_locked += 1;
    }
    else {
        __kmp_acquire_tas_lock_timed_template( lck, gtid );
        lck->lk.depth_locked = 1;
    }
}

static void
__kmp_acquire_nested_tas_lock_with_checks( kmp_tas_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_set_nest_lock";
    if ( ! __kmp_is_tas_lock_nestable( lck ) ) {
        KMP_FATAL( LockSimpleUsedAsNestable, func );
    }
    __kmp_acquire_nested_tas_lock( lck, gtid );
}

int
__kmp_test_nested_tas_lock( kmp_tas_lock_t *lck, kmp_int32 gtid )
{
    int retval;

    KMP_DEBUG_ASSERT( gtid >= 0 );

    if ( __kmp_get_tas_lock_owner( lck ) == gtid ) {
        retval = ++lck->lk.depth_locked;
    }
    else if ( !__kmp_test_tas_lock( lck, gtid ) ) {
        retval = 0;
    }
    else {
        KMP_MB();
        retval = lck->lk.depth_locked = 1;
    }
    return retval;
}

static int
__kmp_test_nested_tas_lock_with_checks( kmp_tas_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_test_nest_lock";
    if ( ! __kmp_is_tas_lock_nestable( lck ) ) {
        KMP_FATAL( LockSimpleUsedAsNestable, func );
    }
    return __kmp_test_nested_tas_lock( lck, gtid );
}

void
__kmp_release_nested_tas_lock( kmp_tas_lock_t *lck, kmp_int32 gtid )
{
    KMP_DEBUG_ASSERT( gtid >= 0 );

    KMP_MB();
    if ( --(lck->lk.depth_locked) == 0 ) {
        __kmp_release_tas_lock( lck, gtid );
    }
}

static void
__kmp_release_nested_tas_lock_with_checks( kmp_tas_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_unset_nest_lock";
    KMP_MB();  /* in case another processor initialized lock */
    if ( ! __kmp_is_tas_lock_nestable( lck ) ) {
        KMP_FATAL( LockSimpleUsedAsNestable, func );
    }
    if ( __kmp_get_tas_lock_owner( lck ) == -1 ) {
        KMP_FATAL( LockUnsettingFree, func );
    }
    if ( __kmp_get_tas_lock_owner( lck ) != gtid ) {
        KMP_FATAL( LockUnsettingSetByAnother, func );
    }
    __kmp_release_nested_tas_lock( lck, gtid );
}

void
__kmp_init_nested_tas_lock( kmp_tas_lock_t * lck )
{
    __kmp_init_tas_lock( lck );
    lck->lk.depth_locked = 0; // >= 0 for nestable locks, -1 for simple locks
}

static void
__kmp_init_nested_tas_lock_with_checks( kmp_tas_lock_t * lck )
{
    __kmp_init_nested_tas_lock( lck );
}

void
__kmp_destroy_nested_tas_lock( kmp_tas_lock_t *lck )
{
    __kmp_destroy_tas_lock( lck );
    lck->lk.depth_locked = 0;
}

static void
__kmp_destroy_nested_tas_lock_with_checks( kmp_tas_lock_t *lck )
{
    char const * const func = "omp_destroy_nest_lock";
    if ( ! __kmp_is_tas_lock_nestable( lck ) ) {
        KMP_FATAL( LockSimpleUsedAsNestable, func );
    }
    if ( __kmp_get_tas_lock_owner( lck ) != -1 ) {
        KMP_FATAL( LockStillOwned, func );
    }
    __kmp_destroy_nested_tas_lock( lck );
}


#if KMP_OS_LINUX && (KMP_ARCH_X86 || KMP_ARCH_X86_64 || KMP_ARCH_ARM || KMP_ARCH_AARCH64)

/* ------------------------------------------------------------------------ */
/* futex locks */

// futex locks are really just test and set locks, with a different method
// of handling contention.  They take the same amount of space as test and
// set locks, and are allocated the same way (i.e. use the area allocated by
// the compiler for non-nested locks / allocate nested locks on the heap).

static kmp_int32
__kmp_get_futex_lock_owner( kmp_futex_lock_t *lck )
{
    return ( TCR_4( lck->lk.poll ) >> 1 ) - 1;
}

static inline bool
__kmp_is_futex_lock_nestable( kmp_futex_lock_t *lck )
{
    return lck->lk.depth_locked != -1;
}

__forceinline static void
__kmp_acquire_futex_lock_timed_template( kmp_futex_lock_t *lck, kmp_int32 gtid )
{
    kmp_int32 gtid_code = ( gtid + 1 ) << 1;

    KMP_MB();

#ifdef USE_LOCK_PROFILE
    kmp_uint32 curr = TCR_4( lck->lk.poll );
    if ( ( curr != 0 ) && ( curr != gtid_code ) )
        __kmp_printf( "LOCK CONTENTION: %p\n", lck );
    /* else __kmp_printf( "." );*/
#endif /* USE_LOCK_PROFILE */

    KMP_FSYNC_PREPARE( lck );
    KA_TRACE( 1000, ("__kmp_acquire_futex_lock: lck:%p(0x%x), T#%d entering\n",
      lck, lck->lk.poll, gtid ) );

    kmp_int32 poll_val;
    while ( ( poll_val = KMP_COMPARE_AND_STORE_RET32( & ( lck->lk.poll ), 0,
      gtid_code ) ) != 0 ) {
        kmp_int32 cond = poll_val & 1;
        KA_TRACE( 1000, ("__kmp_acquire_futex_lock: lck:%p, T#%d poll_val = 0x%x cond = 0x%x\n",
           lck, gtid, poll_val, cond ) );

        //
        // NOTE: if you try to use the following condition for this branch
        //
        // if ( poll_val & 1 == 0 )
        //
        // Then the 12.0 compiler has a bug where the following block will
        // always be skipped, regardless of the value of the LSB of poll_val.
        //
        if ( ! cond ) {
            //
            // Try to set the lsb in the poll to indicate to the owner
            // thread that they need to wake this thread up.
            //
            if ( ! KMP_COMPARE_AND_STORE_REL32( & ( lck->lk.poll ),
              poll_val, poll_val | 1 ) ) {
                KA_TRACE( 1000, ("__kmp_acquire_futex_lock: lck:%p(0x%x), T#%d can't set bit 0\n",
                  lck, lck->lk.poll, gtid ) );
                continue;
            }
            poll_val |= 1;

            KA_TRACE( 1000, ("__kmp_acquire_futex_lock: lck:%p(0x%x), T#%d bit 0 set\n",
              lck, lck->lk.poll, gtid ) );
        }

        KA_TRACE( 1000, ("__kmp_acquire_futex_lock: lck:%p, T#%d before futex_wait(0x%x)\n",
           lck, gtid, poll_val ) );

        kmp_int32 rc;
        if ( ( rc = syscall( __NR_futex, & ( lck->lk.poll ), FUTEX_WAIT,
          poll_val, NULL, NULL, 0 ) ) != 0 ) {
            KA_TRACE( 1000, ("__kmp_acquire_futex_lock: lck:%p, T#%d futex_wait(0x%x) failed (rc=%d errno=%d)\n",
               lck, gtid, poll_val, rc, errno ) );
            continue;
        }

        KA_TRACE( 1000, ("__kmp_acquire_futex_lock: lck:%p, T#%d after futex_wait(0x%x)\n",
           lck, gtid, poll_val ) );
        //
        // This thread has now done a successful futex wait call and was
        // entered on the OS futex queue.  We must now perform a futex
        // wake call when releasing the lock, as we have no idea how many
        // other threads are in the queue.
        //
        gtid_code |= 1;
    }

    KMP_FSYNC_ACQUIRED( lck );
    KA_TRACE( 1000, ("__kmp_acquire_futex_lock: lck:%p(0x%x), T#%d exiting\n",
      lck, lck->lk.poll, gtid ) );
}

void
__kmp_acquire_futex_lock( kmp_futex_lock_t *lck, kmp_int32 gtid )
{
    __kmp_acquire_futex_lock_timed_template( lck, gtid );
}

static void
__kmp_acquire_futex_lock_with_checks( kmp_futex_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_set_lock";
    if ( ( sizeof ( kmp_futex_lock_t ) <= OMP_LOCK_T_SIZE )
      && __kmp_is_futex_lock_nestable( lck ) ) {
        KMP_FATAL( LockNestableUsedAsSimple, func );
    }
    if ( ( gtid >= 0 ) && ( __kmp_get_futex_lock_owner( lck ) == gtid ) ) {
        KMP_FATAL( LockIsAlreadyOwned, func );
    }
    __kmp_acquire_futex_lock( lck, gtid );
}

int
__kmp_test_futex_lock( kmp_futex_lock_t *lck, kmp_int32 gtid )
{
    if ( KMP_COMPARE_AND_STORE_ACQ32( & ( lck->lk.poll ), 0, ( gtid + 1 ) << 1 ) ) {
        KMP_FSYNC_ACQUIRED( lck );
        return TRUE;
    }
    return FALSE;
}

static int
__kmp_test_futex_lock_with_checks( kmp_futex_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_test_lock";
    if ( ( sizeof ( kmp_futex_lock_t ) <= OMP_LOCK_T_SIZE )
      && __kmp_is_futex_lock_nestable( lck ) ) {
        KMP_FATAL( LockNestableUsedAsSimple, func );
    }
    return __kmp_test_futex_lock( lck, gtid );
}

void
__kmp_release_futex_lock( kmp_futex_lock_t *lck, kmp_int32 gtid )
{
    KMP_MB();       /* Flush all pending memory write invalidates.  */

    KA_TRACE( 1000, ("__kmp_release_futex_lock: lck:%p(0x%x), T#%d entering\n",
      lck, lck->lk.poll, gtid ) );

    KMP_FSYNC_RELEASING(lck);

    kmp_int32 poll_val = KMP_XCHG_FIXED32( & ( lck->lk.poll ), 0 );

    KA_TRACE( 1000, ("__kmp_release_futex_lock: lck:%p, T#%d released poll_val = 0x%x\n",
       lck, gtid, poll_val ) );

    if ( poll_val & 1 ) {
        KA_TRACE( 1000, ("__kmp_release_futex_lock: lck:%p, T#%d futex_wake 1 thread\n",
           lck, gtid ) );
        syscall( __NR_futex, & ( lck->lk.poll ), FUTEX_WAKE, 1, NULL, NULL, 0 );
    }

    KMP_MB();       /* Flush all pending memory write invalidates.  */

    KA_TRACE( 1000, ("__kmp_release_futex_lock: lck:%p(0x%x), T#%d exiting\n",
      lck, lck->lk.poll, gtid ) );

    KMP_YIELD( TCR_4( __kmp_nth ) > ( __kmp_avail_proc ? __kmp_avail_proc :
      __kmp_xproc ) );
}

static void
__kmp_release_futex_lock_with_checks( kmp_futex_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_unset_lock";
    KMP_MB();  /* in case another processor initialized lock */
    if ( ( sizeof ( kmp_futex_lock_t ) <= OMP_LOCK_T_SIZE )
      && __kmp_is_futex_lock_nestable( lck ) ) {
        KMP_FATAL( LockNestableUsedAsSimple, func );
    }
    if ( __kmp_get_futex_lock_owner( lck ) == -1 ) {
        KMP_FATAL( LockUnsettingFree, func );
    }
    if ( ( gtid >= 0 ) && ( __kmp_get_futex_lock_owner( lck ) >= 0 )
      && ( __kmp_get_futex_lock_owner( lck ) != gtid ) ) {
        KMP_FATAL( LockUnsettingSetByAnother, func );
    }
    __kmp_release_futex_lock( lck, gtid );
}

void
__kmp_init_futex_lock( kmp_futex_lock_t * lck )
{
    TCW_4( lck->lk.poll, 0 );
}

static void
__kmp_init_futex_lock_with_checks( kmp_futex_lock_t * lck )
{
    __kmp_init_futex_lock( lck );
}

void
__kmp_destroy_futex_lock( kmp_futex_lock_t *lck )
{
    lck->lk.poll = 0;
}

static void
__kmp_destroy_futex_lock_with_checks( kmp_futex_lock_t *lck )
{
    char const * const func = "omp_destroy_lock";
    if ( ( sizeof ( kmp_futex_lock_t ) <= OMP_LOCK_T_SIZE )
      && __kmp_is_futex_lock_nestable( lck ) ) {
        KMP_FATAL( LockNestableUsedAsSimple, func );
    }
    if ( __kmp_get_futex_lock_owner( lck ) != -1 ) {
        KMP_FATAL( LockStillOwned, func );
    }
    __kmp_destroy_futex_lock( lck );
}


//
// nested futex locks
//

void
__kmp_acquire_nested_futex_lock( kmp_futex_lock_t *lck, kmp_int32 gtid )
{
    KMP_DEBUG_ASSERT( gtid >= 0 );

    if ( __kmp_get_futex_lock_owner( lck ) == gtid ) {
        lck->lk.depth_locked += 1;
    }
    else {
        __kmp_acquire_futex_lock_timed_template( lck, gtid );
        lck->lk.depth_locked = 1;
    }
}

static void
__kmp_acquire_nested_futex_lock_with_checks( kmp_futex_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_set_nest_lock";
    if ( ! __kmp_is_futex_lock_nestable( lck ) ) {
        KMP_FATAL( LockSimpleUsedAsNestable, func );
    }
    __kmp_acquire_nested_futex_lock( lck, gtid );
}

int
__kmp_test_nested_futex_lock( kmp_futex_lock_t *lck, kmp_int32 gtid )
{
    int retval;

    KMP_DEBUG_ASSERT( gtid >= 0 );

    if ( __kmp_get_futex_lock_owner( lck ) == gtid ) {
        retval = ++lck->lk.depth_locked;
    }
    else if ( !__kmp_test_futex_lock( lck, gtid ) ) {
        retval = 0;
    }
    else {
        KMP_MB();
        retval = lck->lk.depth_locked = 1;
    }
    return retval;
}

static int
__kmp_test_nested_futex_lock_with_checks( kmp_futex_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_test_nest_lock";
    if ( ! __kmp_is_futex_lock_nestable( lck ) ) {
        KMP_FATAL( LockSimpleUsedAsNestable, func );
    }
    return __kmp_test_nested_futex_lock( lck, gtid );
}

void
__kmp_release_nested_futex_lock( kmp_futex_lock_t *lck, kmp_int32 gtid )
{
    KMP_DEBUG_ASSERT( gtid >= 0 );

    KMP_MB();
    if ( --(lck->lk.depth_locked) == 0 ) {
        __kmp_release_futex_lock( lck, gtid );
    }
}

static void
__kmp_release_nested_futex_lock_with_checks( kmp_futex_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_unset_nest_lock";
    KMP_MB();  /* in case another processor initialized lock */
    if ( ! __kmp_is_futex_lock_nestable( lck ) ) {
        KMP_FATAL( LockSimpleUsedAsNestable, func );
    }
    if ( __kmp_get_futex_lock_owner( lck ) == -1 ) {
        KMP_FATAL( LockUnsettingFree, func );
    }
    if ( __kmp_get_futex_lock_owner( lck ) != gtid ) {
        KMP_FATAL( LockUnsettingSetByAnother, func );
    }
    __kmp_release_nested_futex_lock( lck, gtid );
}

void
__kmp_init_nested_futex_lock( kmp_futex_lock_t * lck )
{
    __kmp_init_futex_lock( lck );
    lck->lk.depth_locked = 0; // >= 0 for nestable locks, -1 for simple locks
}

static void
__kmp_init_nested_futex_lock_with_checks( kmp_futex_lock_t * lck )
{
    __kmp_init_nested_futex_lock( lck );
}

void
__kmp_destroy_nested_futex_lock( kmp_futex_lock_t *lck )
{
    __kmp_destroy_futex_lock( lck );
    lck->lk.depth_locked = 0;
}

static void
__kmp_destroy_nested_futex_lock_with_checks( kmp_futex_lock_t *lck )
{
    char const * const func = "omp_destroy_nest_lock";
    if ( ! __kmp_is_futex_lock_nestable( lck ) ) {
        KMP_FATAL( LockSimpleUsedAsNestable, func );
    }
    if ( __kmp_get_futex_lock_owner( lck ) != -1 ) {
        KMP_FATAL( LockStillOwned, func );
    }
    __kmp_destroy_nested_futex_lock( lck );
}

#endif // KMP_OS_LINUX && (KMP_ARCH_X86 || KMP_ARCH_X86_64 || KMP_ARCH_ARM)


/* ------------------------------------------------------------------------ */
/* ticket (bakery) locks */

static kmp_int32
__kmp_get_ticket_lock_owner( kmp_ticket_lock_t *lck )
{
    return TCR_4( lck->lk.owner_id ) - 1;
}

static inline bool
__kmp_is_ticket_lock_nestable( kmp_ticket_lock_t *lck )
{
    return lck->lk.depth_locked != -1;
}

static kmp_uint32
__kmp_bakery_check(kmp_uint value, kmp_uint checker)
{
    register kmp_uint32 pause;

    if (value == checker) {
        return TRUE;
    }
    for (pause = checker - value; pause != 0; --pause);
    return FALSE;
}

__forceinline static void
__kmp_acquire_ticket_lock_timed_template( kmp_ticket_lock_t *lck, kmp_int32 gtid )
{
    kmp_uint32 my_ticket;
    KMP_MB();

    my_ticket = KMP_TEST_THEN_INC32( (kmp_int32 *) &lck->lk.next_ticket );

#ifdef USE_LOCK_PROFILE
    if ( TCR_4( lck->lk.now_serving ) != my_ticket )
        __kmp_printf( "LOCK CONTENTION: %p\n", lck );
    /* else __kmp_printf( "." );*/
#endif /* USE_LOCK_PROFILE */

    if ( TCR_4( lck->lk.now_serving ) == my_ticket ) {
        KMP_FSYNC_ACQUIRED(lck);
        return;
    }
    KMP_WAIT_YIELD( &lck->lk.now_serving, my_ticket, __kmp_bakery_check, lck );
    KMP_FSYNC_ACQUIRED(lck);
}

void
__kmp_acquire_ticket_lock( kmp_ticket_lock_t *lck, kmp_int32 gtid )
{
    __kmp_acquire_ticket_lock_timed_template( lck, gtid );
}

static void
__kmp_acquire_ticket_lock_with_checks( kmp_ticket_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_set_lock";
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( __kmp_is_ticket_lock_nestable( lck ) ) {
        KMP_FATAL( LockNestableUsedAsSimple, func );
    }
    if ( ( gtid >= 0 ) && ( __kmp_get_ticket_lock_owner( lck ) == gtid ) ) {
        KMP_FATAL( LockIsAlreadyOwned, func );
    }

    __kmp_acquire_ticket_lock( lck, gtid );

    lck->lk.owner_id = gtid + 1;
}

int
__kmp_test_ticket_lock( kmp_ticket_lock_t *lck, kmp_int32 gtid )
{
    kmp_uint32 my_ticket = TCR_4( lck->lk.next_ticket );
    if ( TCR_4( lck->lk.now_serving ) == my_ticket ) {
        kmp_uint32 next_ticket = my_ticket + 1;
        if ( KMP_COMPARE_AND_STORE_ACQ32( (kmp_int32 *) &lck->lk.next_ticket,
          my_ticket, next_ticket ) ) {
            KMP_FSYNC_ACQUIRED( lck );
            return TRUE;
        }
    }
    return FALSE;
}

static int
__kmp_test_ticket_lock_with_checks( kmp_ticket_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_test_lock";
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( __kmp_is_ticket_lock_nestable( lck ) ) {
        KMP_FATAL( LockNestableUsedAsSimple, func );
    }

    int retval = __kmp_test_ticket_lock( lck, gtid );

    if ( retval ) {
        lck->lk.owner_id = gtid + 1;
    }
    return retval;
}

void
__kmp_release_ticket_lock( kmp_ticket_lock_t *lck, kmp_int32 gtid )
{
    kmp_uint32  distance;

    KMP_MB();       /* Flush all pending memory write invalidates.  */

    KMP_FSYNC_RELEASING(lck);
    distance = ( TCR_4( lck->lk.next_ticket ) - TCR_4( lck->lk.now_serving ) );

    KMP_ST_REL32( &(lck->lk.now_serving), lck->lk.now_serving + 1 );

    KMP_MB();       /* Flush all pending memory write invalidates.  */

    KMP_YIELD( distance
      > (kmp_uint32) (__kmp_avail_proc ? __kmp_avail_proc : __kmp_xproc) );
}

static void
__kmp_release_ticket_lock_with_checks( kmp_ticket_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_unset_lock";
    KMP_MB();  /* in case another processor initialized lock */
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( __kmp_is_ticket_lock_nestable( lck ) ) {
        KMP_FATAL( LockNestableUsedAsSimple, func );
    }
    if ( __kmp_get_ticket_lock_owner( lck ) == -1 ) {
        KMP_FATAL( LockUnsettingFree, func );
    }
    if ( ( gtid >= 0 ) && ( __kmp_get_ticket_lock_owner( lck ) >= 0 )
      && ( __kmp_get_ticket_lock_owner( lck ) != gtid ) ) {
        KMP_FATAL( LockUnsettingSetByAnother, func );
    }
    lck->lk.owner_id = 0;
    __kmp_release_ticket_lock( lck, gtid );
}

void
__kmp_init_ticket_lock( kmp_ticket_lock_t * lck )
{
    lck->lk.location = NULL;
    TCW_4( lck->lk.next_ticket, 0 );
    TCW_4( lck->lk.now_serving, 0 );
    lck->lk.owner_id = 0;      // no thread owns the lock.
    lck->lk.depth_locked = -1; // -1 => not a nested lock.
    lck->lk.initialized = (kmp_ticket_lock *)lck;
}

static void
__kmp_init_ticket_lock_with_checks( kmp_ticket_lock_t * lck )
{
    __kmp_init_ticket_lock( lck );
}

void
__kmp_destroy_ticket_lock( kmp_ticket_lock_t *lck )
{
    lck->lk.initialized = NULL;
    lck->lk.location    = NULL;
    lck->lk.next_ticket = 0;
    lck->lk.now_serving = 0;
    lck->lk.owner_id = 0;
    lck->lk.depth_locked = -1;
}

static void
__kmp_destroy_ticket_lock_with_checks( kmp_ticket_lock_t *lck )
{
    char const * const func = "omp_destroy_lock";
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( __kmp_is_ticket_lock_nestable( lck ) ) {
        KMP_FATAL( LockNestableUsedAsSimple, func );
    }
    if ( __kmp_get_ticket_lock_owner( lck ) != -1 ) {
        KMP_FATAL( LockStillOwned, func );
    }
    __kmp_destroy_ticket_lock( lck );
}


//
// nested ticket locks
//

void
__kmp_acquire_nested_ticket_lock( kmp_ticket_lock_t *lck, kmp_int32 gtid )
{
    KMP_DEBUG_ASSERT( gtid >= 0 );

    if ( __kmp_get_ticket_lock_owner( lck ) == gtid ) {
        lck->lk.depth_locked += 1;
    }
    else {
        __kmp_acquire_ticket_lock_timed_template( lck, gtid );
        KMP_MB();
        lck->lk.depth_locked = 1;
        KMP_MB();
        lck->lk.owner_id = gtid + 1;
    }
}

static void
__kmp_acquire_nested_ticket_lock_with_checks( kmp_ticket_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_set_nest_lock";
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( ! __kmp_is_ticket_lock_nestable( lck ) ) {
        KMP_FATAL( LockSimpleUsedAsNestable, func );
    }
    __kmp_acquire_nested_ticket_lock( lck, gtid );
}

int
__kmp_test_nested_ticket_lock( kmp_ticket_lock_t *lck, kmp_int32 gtid )
{
    int retval;

    KMP_DEBUG_ASSERT( gtid >= 0 );

    if ( __kmp_get_ticket_lock_owner( lck ) == gtid ) {
        retval = ++lck->lk.depth_locked;
    }
    else if ( !__kmp_test_ticket_lock( lck, gtid ) ) {
        retval = 0;
    }
    else {
        KMP_MB();
        retval = lck->lk.depth_locked = 1;
        KMP_MB();
        lck->lk.owner_id = gtid + 1;
    }
    return retval;
}

static int
__kmp_test_nested_ticket_lock_with_checks( kmp_ticket_lock_t *lck,
  kmp_int32 gtid )
{
    char const * const func = "omp_test_nest_lock";
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( ! __kmp_is_ticket_lock_nestable( lck ) ) {
        KMP_FATAL( LockSimpleUsedAsNestable, func );
    }
    return __kmp_test_nested_ticket_lock( lck, gtid );
}

void
__kmp_release_nested_ticket_lock( kmp_ticket_lock_t *lck, kmp_int32 gtid )
{
    KMP_DEBUG_ASSERT( gtid >= 0 );

    KMP_MB();
    if ( --(lck->lk.depth_locked) == 0 ) {
        KMP_MB();
        lck->lk.owner_id = 0;
        __kmp_release_ticket_lock( lck, gtid );
    }
}

static void
__kmp_release_nested_ticket_lock_with_checks( kmp_ticket_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_unset_nest_lock";
    KMP_MB();  /* in case another processor initialized lock */
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( ! __kmp_is_ticket_lock_nestable( lck ) ) {
        KMP_FATAL( LockSimpleUsedAsNestable, func );
    }
    if ( __kmp_get_ticket_lock_owner( lck ) == -1 ) {
        KMP_FATAL( LockUnsettingFree, func );
    }
    if ( __kmp_get_ticket_lock_owner( lck ) != gtid ) {
        KMP_FATAL( LockUnsettingSetByAnother, func );
    }
    __kmp_release_nested_ticket_lock( lck, gtid );
}

void
__kmp_init_nested_ticket_lock( kmp_ticket_lock_t * lck )
{
    __kmp_init_ticket_lock( lck );
    lck->lk.depth_locked = 0; // >= 0 for nestable locks, -1 for simple locks
}

static void
__kmp_init_nested_ticket_lock_with_checks( kmp_ticket_lock_t * lck )
{
    __kmp_init_nested_ticket_lock( lck );
}

void
__kmp_destroy_nested_ticket_lock( kmp_ticket_lock_t *lck )
{
    __kmp_destroy_ticket_lock( lck );
    lck->lk.depth_locked = 0;
}

static void
__kmp_destroy_nested_ticket_lock_with_checks( kmp_ticket_lock_t *lck )
{
    char const * const func = "omp_destroy_nest_lock";
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( ! __kmp_is_ticket_lock_nestable( lck ) ) {
        KMP_FATAL( LockSimpleUsedAsNestable, func );
    }
    if ( __kmp_get_ticket_lock_owner( lck ) != -1 ) {
        KMP_FATAL( LockStillOwned, func );
    }
    __kmp_destroy_nested_ticket_lock( lck );
}


//
// access functions to fields which don't exist for all lock kinds.
//

static int
__kmp_is_ticket_lock_initialized( kmp_ticket_lock_t *lck )
{
    return lck == lck->lk.initialized;
}

static const ident_t *
__kmp_get_ticket_lock_location( kmp_ticket_lock_t *lck )
{
    return lck->lk.location;
}

static void
__kmp_set_ticket_lock_location( kmp_ticket_lock_t *lck, const ident_t *loc )
{
    lck->lk.location = loc;
}

static kmp_lock_flags_t
__kmp_get_ticket_lock_flags( kmp_ticket_lock_t *lck )
{
    return lck->lk.flags;
}

static void
__kmp_set_ticket_lock_flags( kmp_ticket_lock_t *lck, kmp_lock_flags_t flags )
{
    lck->lk.flags = flags;
}

/* ------------------------------------------------------------------------ */
/* queuing locks */

/*
 * First the states
 * (head,tail) =  0, 0  means lock is unheld, nobody on queue
 *   UINT_MAX or -1, 0  means lock is held, nobody on queue
 *                h, h  means lock is held or about to transition, 1 element on queue
 *                h, t  h <> t, means lock is held or about to transition, >1 elements on queue
 *
 * Now the transitions
 *    Acquire(0,0)  = -1 ,0
 *    Release(0,0)  = Error
 *    Acquire(-1,0) =  h ,h    h > 0
 *    Release(-1,0) =  0 ,0
 *    Acquire(h,h)  =  h ,t    h > 0, t > 0, h <> t
 *    Release(h,h)  = -1 ,0    h > 0
 *    Acquire(h,t)  =  h ,t'   h > 0, t > 0, t' > 0, h <> t, h <> t', t <> t'
 *    Release(h,t)  =  h',t    h > 0, t > 0, h <> t, h <> h', h' maybe = t
 *
 * And pictorially
 *
 *
 *          +-----+
 *          | 0, 0|------- release -------> Error
 *          +-----+
 *            |  ^
 *     acquire|  |release
 *            |  |
 *            |  |
 *            v  |
 *          +-----+
 *          |-1, 0|
 *          +-----+
 *            |  ^
 *     acquire|  |release
 *            |  |
 *            |  |
 *            v  |
 *          +-----+
 *          | h, h|
 *          +-----+
 *            |  ^
 *     acquire|  |release
 *            |  |
 *            |  |
 *            v  |
 *          +-----+
 *          | h, t|----- acquire, release loopback ---+
 *          +-----+                                   |
 *               ^                                    |
 *               |                                    |
 *               +------------------------------------+
 *
 */

#ifdef DEBUG_QUEUING_LOCKS

/* Stuff for circular trace buffer */
#define TRACE_BUF_ELE	1024
static char traces[TRACE_BUF_ELE][128] = { 0 }
static int tc = 0;
#define TRACE_LOCK(X,Y)          sprintf( traces[tc++ % TRACE_BUF_ELE], "t%d at %s\n", X, Y );
#define TRACE_LOCK_T(X,Y,Z)      sprintf( traces[tc++ % TRACE_BUF_ELE], "t%d at %s%d\n", X,Y,Z );
#define TRACE_LOCK_HT(X,Y,Z,Q)   sprintf( traces[tc++ % TRACE_BUF_ELE], "t%d at %s %d,%d\n", X, Y, Z, Q );

static void
__kmp_dump_queuing_lock( kmp_info_t *this_thr, kmp_int32 gtid,
  kmp_queuing_lock_t *lck, kmp_int32 head_id, kmp_int32 tail_id )
{
    kmp_int32 t, i;

    __kmp_printf_no_lock( "\n__kmp_dump_queuing_lock: TRACE BEGINS HERE! \n" );

    i = tc % TRACE_BUF_ELE;
    __kmp_printf_no_lock( "%s\n", traces[i] );
    i = (i+1) % TRACE_BUF_ELE;
    while ( i != (tc % TRACE_BUF_ELE) ) {
        __kmp_printf_no_lock( "%s", traces[i] );
        i = (i+1) % TRACE_BUF_ELE;
    }
    __kmp_printf_no_lock( "\n" );

    __kmp_printf_no_lock(
             "\n__kmp_dump_queuing_lock: gtid+1:%d, spin_here:%d, next_wait:%d, head_id:%d, tail_id:%d\n",
             gtid+1, this_thr->th.th_spin_here, this_thr->th.th_next_waiting,
             head_id, tail_id );

    __kmp_printf_no_lock( "\t\thead: %d ", lck->lk.head_id );

    if ( lck->lk.head_id >= 1 ) {
        t = __kmp_threads[lck->lk.head_id-1]->th.th_next_waiting;
        while (t > 0) {
            __kmp_printf_no_lock( "-> %d ", t );
            t = __kmp_threads[t-1]->th.th_next_waiting;
        }
    }
    __kmp_printf_no_lock( ";  tail: %d ", lck->lk.tail_id );
    __kmp_printf_no_lock( "\n\n" );
}

#endif /* DEBUG_QUEUING_LOCKS */

static kmp_int32
__kmp_get_queuing_lock_owner( kmp_queuing_lock_t *lck )
{
    return TCR_4( lck->lk.owner_id ) - 1;
}

static inline bool
__kmp_is_queuing_lock_nestable( kmp_queuing_lock_t *lck )
{
    return lck->lk.depth_locked != -1;
}

/* Acquire a lock using a the queuing lock implementation */
template <bool takeTime>
/* [TLW] The unused template above is left behind because of what BEB believes is a
   potential compiler problem with __forceinline. */
__forceinline static void
__kmp_acquire_queuing_lock_timed_template( kmp_queuing_lock_t *lck,
  kmp_int32 gtid )
{
    register kmp_info_t *this_thr    = __kmp_thread_from_gtid( gtid );
    volatile kmp_int32  *head_id_p   = & lck->lk.head_id;
    volatile kmp_int32  *tail_id_p   = & lck->lk.tail_id;
    volatile kmp_uint32 *spin_here_p;
    kmp_int32 need_mf = 1;

    KA_TRACE( 1000, ("__kmp_acquire_queuing_lock: lck:%p, T#%d entering\n", lck, gtid ));

    KMP_FSYNC_PREPARE( lck );
    KMP_DEBUG_ASSERT( this_thr != NULL );
    spin_here_p = & this_thr->th.th_spin_here;

#ifdef DEBUG_QUEUING_LOCKS
    TRACE_LOCK( gtid+1, "acq ent" );
    if ( *spin_here_p )
        __kmp_dump_queuing_lock( this_thr, gtid, lck, *head_id_p, *tail_id_p );
    if ( this_thr->th.th_next_waiting != 0 )
        __kmp_dump_queuing_lock( this_thr, gtid, lck, *head_id_p, *tail_id_p );
#endif
    KMP_DEBUG_ASSERT( !*spin_here_p );
    KMP_DEBUG_ASSERT( this_thr->th.th_next_waiting == 0 );


    /* The following st.rel to spin_here_p needs to precede the cmpxchg.acq to head_id_p
       that may follow, not just in execution order, but also in visibility order.  This way,
       when a releasing thread observes the changes to the queue by this thread, it can
       rightly assume that spin_here_p has already been set to TRUE, so that when it sets
       spin_here_p to FALSE, it is not premature.  If the releasing thread sets spin_here_p
       to FALSE before this thread sets it to TRUE, this thread will hang.
    */
    *spin_here_p = TRUE;  /* before enqueuing to prevent race */

    while( 1 ) {
        kmp_int32 enqueued;
        kmp_int32 head;
        kmp_int32 tail;

        head = *head_id_p;

        switch ( head ) {

            case -1:
            {
#ifdef DEBUG_QUEUING_LOCKS
                tail = *tail_id_p;
                TRACE_LOCK_HT( gtid+1, "acq read: ", head, tail );
#endif
                tail = 0;  /* to make sure next link asynchronously read is not set accidentally;
                           this assignment prevents us from entering the if ( t > 0 )
                           condition in the enqueued case below, which is not necessary for
                           this state transition */

                need_mf = 0;
                /* try (-1,0)->(tid,tid) */
                enqueued = KMP_COMPARE_AND_STORE_ACQ64( (volatile kmp_int64 *) tail_id_p,
                  KMP_PACK_64( -1, 0 ),
                  KMP_PACK_64( gtid+1, gtid+1 ) );
#ifdef DEBUG_QUEUING_LOCKS
                  if ( enqueued ) TRACE_LOCK( gtid+1, "acq enq: (-1,0)->(tid,tid)" );
#endif
            }
            break;

            default:
            {
                tail = *tail_id_p;
                KMP_DEBUG_ASSERT( tail != gtid + 1 );

#ifdef DEBUG_QUEUING_LOCKS
                TRACE_LOCK_HT( gtid+1, "acq read: ", head, tail );
#endif

                if ( tail == 0 ) {
                    enqueued = FALSE;
                }
                else {
                    need_mf = 0;
                    /* try (h,t) or (h,h)->(h,tid) */
                    enqueued = KMP_COMPARE_AND_STORE_ACQ32( tail_id_p, tail, gtid+1 );

#ifdef DEBUG_QUEUING_LOCKS
                        if ( enqueued ) TRACE_LOCK( gtid+1, "acq enq: (h,t)->(h,tid)" );
#endif
                }
            }
            break;

            case 0: /* empty queue */
            {
                kmp_int32 grabbed_lock;

#ifdef DEBUG_QUEUING_LOCKS
                tail = *tail_id_p;
                TRACE_LOCK_HT( gtid+1, "acq read: ", head, tail );
#endif
                /* try (0,0)->(-1,0) */

                /* only legal transition out of head = 0 is head = -1 with no change to tail */
                grabbed_lock = KMP_COMPARE_AND_STORE_ACQ32( head_id_p, 0, -1 );

                if ( grabbed_lock ) {

                    *spin_here_p = FALSE;

                    KA_TRACE( 1000, ("__kmp_acquire_queuing_lock: lck:%p, T#%d exiting: no queuing\n",
                              lck, gtid ));
#ifdef DEBUG_QUEUING_LOCKS
                    TRACE_LOCK_HT( gtid+1, "acq exit: ", head, 0 );
#endif
                    KMP_FSYNC_ACQUIRED( lck );
                    return; /* lock holder cannot be on queue */
                }
                enqueued = FALSE;
            }
            break;
        }

        if ( enqueued ) {
            if ( tail > 0 ) {
                kmp_info_t *tail_thr = __kmp_thread_from_gtid( tail - 1 );
                KMP_ASSERT( tail_thr != NULL );
                tail_thr->th.th_next_waiting = gtid+1;
                /* corresponding wait for this write in release code */
            }
            KA_TRACE( 1000, ("__kmp_acquire_queuing_lock: lck:%p, T#%d waiting for lock\n", lck, gtid ));


            /* ToDo: May want to consider using __kmp_wait_sleep  or something that sleeps for
             *       throughput only here.
             */
            KMP_MB();
            KMP_WAIT_YIELD(spin_here_p, FALSE, KMP_EQ, lck);

#ifdef DEBUG_QUEUING_LOCKS
            TRACE_LOCK( gtid+1, "acq spin" );

            if ( this_thr->th.th_next_waiting != 0 )
                __kmp_dump_queuing_lock( this_thr, gtid, lck, *head_id_p, *tail_id_p );
#endif
            KMP_DEBUG_ASSERT( this_thr->th.th_next_waiting == 0 );
            KA_TRACE( 1000, ("__kmp_acquire_queuing_lock: lck:%p, T#%d exiting: after waiting on queue\n",
                      lck, gtid ));

#ifdef DEBUG_QUEUING_LOCKS
            TRACE_LOCK( gtid+1, "acq exit 2" );
#endif
            /* got lock, we were dequeued by the thread that released lock */
            return;
        }

        /* Yield if number of threads > number of logical processors */
        /* ToDo: Not sure why this should only be in oversubscription case,
           maybe should be traditional YIELD_INIT/YIELD_WHEN loop */
        KMP_YIELD( TCR_4( __kmp_nth ) > (__kmp_avail_proc ? __kmp_avail_proc :
          __kmp_xproc ) );
#ifdef DEBUG_QUEUING_LOCKS
        TRACE_LOCK( gtid+1, "acq retry" );
#endif

    }
    KMP_ASSERT2( 0, "should not get here" );
}

void
__kmp_acquire_queuing_lock( kmp_queuing_lock_t *lck, kmp_int32 gtid )
{
    KMP_DEBUG_ASSERT( gtid >= 0 );

    __kmp_acquire_queuing_lock_timed_template<false>( lck, gtid );
}

static void
__kmp_acquire_queuing_lock_with_checks( kmp_queuing_lock_t *lck,
  kmp_int32 gtid )
{
    char const * const func = "omp_set_lock";
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( __kmp_is_queuing_lock_nestable( lck ) ) {
        KMP_FATAL( LockNestableUsedAsSimple, func );
    }
    if ( __kmp_get_queuing_lock_owner( lck ) == gtid ) {
        KMP_FATAL( LockIsAlreadyOwned, func );
    }

    __kmp_acquire_queuing_lock( lck, gtid );

    lck->lk.owner_id = gtid + 1;
}

int
__kmp_test_queuing_lock( kmp_queuing_lock_t *lck, kmp_int32 gtid )
{
    volatile kmp_int32 *head_id_p  = & lck->lk.head_id;
    kmp_int32 head;
#ifdef KMP_DEBUG
    kmp_info_t *this_thr;
#endif

    KA_TRACE( 1000, ("__kmp_test_queuing_lock: T#%d entering\n", gtid ));
    KMP_DEBUG_ASSERT( gtid >= 0 );
#ifdef KMP_DEBUG
    this_thr = __kmp_thread_from_gtid( gtid );
    KMP_DEBUG_ASSERT( this_thr != NULL );
    KMP_DEBUG_ASSERT( !this_thr->th.th_spin_here );
#endif

    head = *head_id_p;

    if ( head == 0 ) { /* nobody on queue, nobody holding */

        /* try (0,0)->(-1,0) */

        if ( KMP_COMPARE_AND_STORE_ACQ32( head_id_p, 0, -1 ) ) {
            KA_TRACE( 1000, ("__kmp_test_queuing_lock: T#%d exiting: holding lock\n", gtid ));
            KMP_FSYNC_ACQUIRED(lck);
            return TRUE;
        }
    }

    KA_TRACE( 1000, ("__kmp_test_queuing_lock: T#%d exiting: without lock\n", gtid ));
    return FALSE;
}

static int
__kmp_test_queuing_lock_with_checks( kmp_queuing_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_test_lock";
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( __kmp_is_queuing_lock_nestable( lck ) ) {
        KMP_FATAL( LockNestableUsedAsSimple, func );
    }

    int retval = __kmp_test_queuing_lock( lck, gtid );

    if ( retval ) {
        lck->lk.owner_id = gtid + 1;
    }
    return retval;
}

void
__kmp_release_queuing_lock( kmp_queuing_lock_t *lck, kmp_int32 gtid )
{
    register kmp_info_t *this_thr;
    volatile kmp_int32 *head_id_p = & lck->lk.head_id;
    volatile kmp_int32 *tail_id_p = & lck->lk.tail_id;

    KA_TRACE( 1000, ("__kmp_release_queuing_lock: lck:%p, T#%d entering\n", lck, gtid ));
    KMP_DEBUG_ASSERT( gtid >= 0 );
    this_thr    = __kmp_thread_from_gtid( gtid );
    KMP_DEBUG_ASSERT( this_thr != NULL );
#ifdef DEBUG_QUEUING_LOCKS
    TRACE_LOCK( gtid+1, "rel ent" );

    if ( this_thr->th.th_spin_here )
        __kmp_dump_queuing_lock( this_thr, gtid, lck, *head_id_p, *tail_id_p );
    if ( this_thr->th.th_next_waiting != 0 )
        __kmp_dump_queuing_lock( this_thr, gtid, lck, *head_id_p, *tail_id_p );
#endif
    KMP_DEBUG_ASSERT( !this_thr->th.th_spin_here );
    KMP_DEBUG_ASSERT( this_thr->th.th_next_waiting == 0 );

    KMP_FSYNC_RELEASING(lck);

    while( 1 ) {
        kmp_int32 dequeued;
        kmp_int32 head;
        kmp_int32 tail;

        head = *head_id_p;

#ifdef DEBUG_QUEUING_LOCKS
        tail = *tail_id_p;
        TRACE_LOCK_HT( gtid+1, "rel read: ", head, tail );
        if ( head == 0 ) __kmp_dump_queuing_lock( this_thr, gtid, lck, head, tail );
#endif
        KMP_DEBUG_ASSERT( head != 0 ); /* holding the lock, head must be -1 or queue head */

        if ( head == -1 ) { /* nobody on queue */

            /* try (-1,0)->(0,0) */
            if ( KMP_COMPARE_AND_STORE_REL32( head_id_p, -1, 0 ) ) {
                KA_TRACE( 1000, ("__kmp_release_queuing_lock: lck:%p, T#%d exiting: queue empty\n",
                          lck, gtid ));
#ifdef DEBUG_QUEUING_LOCKS
                TRACE_LOCK_HT( gtid+1, "rel exit: ", 0, 0 );
#endif
                return;
            }
            dequeued = FALSE;

        }
        else {

            tail = *tail_id_p;
            if ( head == tail ) {  /* only one thread on the queue */

#ifdef DEBUG_QUEUING_LOCKS
                if ( head <= 0 ) __kmp_dump_queuing_lock( this_thr, gtid, lck, head, tail );
#endif
                KMP_DEBUG_ASSERT( head > 0 );

                /* try (h,h)->(-1,0) */
                dequeued = KMP_COMPARE_AND_STORE_REL64( (kmp_int64 *) tail_id_p,
                  KMP_PACK_64( head, head ), KMP_PACK_64( -1, 0 ) );
#ifdef DEBUG_QUEUING_LOCKS
                TRACE_LOCK( gtid+1, "rel deq: (h,h)->(-1,0)" );
#endif

            }
            else {
                volatile kmp_int32 *waiting_id_p;
                kmp_info_t         *head_thr = __kmp_thread_from_gtid( head - 1 );
                KMP_DEBUG_ASSERT( head_thr != NULL );
                waiting_id_p = & head_thr->th.th_next_waiting;

                /* Does this require synchronous reads? */
#ifdef DEBUG_QUEUING_LOCKS
                if ( head <= 0 || tail <= 0 ) __kmp_dump_queuing_lock( this_thr, gtid, lck, head, tail );
#endif
                KMP_DEBUG_ASSERT( head > 0 && tail > 0 );

                /* try (h,t)->(h',t) or (t,t) */

                KMP_MB();
                /* make sure enqueuing thread has time to update next waiting thread field */
                *head_id_p = (kmp_int32) KMP_WAIT_YIELD((volatile kmp_uint*) waiting_id_p, 0, KMP_NEQ, NULL);
#ifdef DEBUG_QUEUING_LOCKS
                TRACE_LOCK( gtid+1, "rel deq: (h,t)->(h',t)" );
#endif
                dequeued = TRUE;
            }
        }

        if ( dequeued ) {
            kmp_info_t *head_thr = __kmp_thread_from_gtid( head - 1 );
            KMP_DEBUG_ASSERT( head_thr != NULL );

            /* Does this require synchronous reads? */
#ifdef DEBUG_QUEUING_LOCKS
            if ( head <= 0 || tail <= 0 ) __kmp_dump_queuing_lock( this_thr, gtid, lck, head, tail );
#endif
            KMP_DEBUG_ASSERT( head > 0 && tail > 0 );

            /* For clean code only.
             * Thread not released until next statement prevents race with acquire code.
             */
            head_thr->th.th_next_waiting = 0;
#ifdef DEBUG_QUEUING_LOCKS
            TRACE_LOCK_T( gtid+1, "rel nw=0 for t=", head );
#endif

            KMP_MB();
            /* reset spin value */
            head_thr->th.th_spin_here = FALSE;

            KA_TRACE( 1000, ("__kmp_release_queuing_lock: lck:%p, T#%d exiting: after dequeuing\n",
                      lck, gtid ));
#ifdef DEBUG_QUEUING_LOCKS
            TRACE_LOCK( gtid+1, "rel exit 2" );
#endif
            return;
        }
        /* KMP_CPU_PAUSE( );  don't want to make releasing thread hold up acquiring threads */

#ifdef DEBUG_QUEUING_LOCKS
        TRACE_LOCK( gtid+1, "rel retry" );
#endif

    } /* while */
    KMP_ASSERT2( 0, "should not get here" );
}

static void
__kmp_release_queuing_lock_with_checks( kmp_queuing_lock_t *lck,
  kmp_int32 gtid )
{
    char const * const func = "omp_unset_lock";
    KMP_MB();  /* in case another processor initialized lock */
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( __kmp_is_queuing_lock_nestable( lck ) ) {
        KMP_FATAL( LockNestableUsedAsSimple, func );
    }
    if ( __kmp_get_queuing_lock_owner( lck ) == -1 ) {
        KMP_FATAL( LockUnsettingFree, func );
    }
    if ( __kmp_get_queuing_lock_owner( lck ) != gtid ) {
        KMP_FATAL( LockUnsettingSetByAnother, func );
    }
    lck->lk.owner_id = 0;
    __kmp_release_queuing_lock( lck, gtid );
}

void
__kmp_init_queuing_lock( kmp_queuing_lock_t *lck )
{
    lck->lk.location = NULL;
    lck->lk.head_id = 0;
    lck->lk.tail_id = 0;
    lck->lk.next_ticket = 0;
    lck->lk.now_serving = 0;
    lck->lk.owner_id = 0;      // no thread owns the lock.
    lck->lk.depth_locked = -1; // >= 0 for nestable locks, -1 for simple locks.
    lck->lk.initialized = lck;

    KA_TRACE(1000, ("__kmp_init_queuing_lock: lock %p initialized\n", lck));
}

static void
__kmp_init_queuing_lock_with_checks( kmp_queuing_lock_t * lck )
{
    __kmp_init_queuing_lock( lck );
}

void
__kmp_destroy_queuing_lock( kmp_queuing_lock_t *lck )
{
    lck->lk.initialized = NULL;
    lck->lk.location = NULL;
    lck->lk.head_id = 0;
    lck->lk.tail_id = 0;
    lck->lk.next_ticket = 0;
    lck->lk.now_serving = 0;
    lck->lk.owner_id = 0;
    lck->lk.depth_locked = -1;
}

static void
__kmp_destroy_queuing_lock_with_checks( kmp_queuing_lock_t *lck )
{
    char const * const func = "omp_destroy_lock";
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( __kmp_is_queuing_lock_nestable( lck ) ) {
        KMP_FATAL( LockNestableUsedAsSimple, func );
    }
    if ( __kmp_get_queuing_lock_owner( lck ) != -1 ) {
        KMP_FATAL( LockStillOwned, func );
    }
    __kmp_destroy_queuing_lock( lck );
}


//
// nested queuing locks
//

void
__kmp_acquire_nested_queuing_lock( kmp_queuing_lock_t *lck, kmp_int32 gtid )
{
    KMP_DEBUG_ASSERT( gtid >= 0 );

    if ( __kmp_get_queuing_lock_owner( lck ) == gtid ) {
        lck->lk.depth_locked += 1;
    }
    else {
        __kmp_acquire_queuing_lock_timed_template<false>( lck, gtid );
        KMP_MB();
        lck->lk.depth_locked = 1;
        KMP_MB();
        lck->lk.owner_id = gtid + 1;
    }
}

static void
__kmp_acquire_nested_queuing_lock_with_checks( kmp_queuing_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_set_nest_lock";
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( ! __kmp_is_queuing_lock_nestable( lck ) ) {
        KMP_FATAL( LockSimpleUsedAsNestable, func );
    }
    __kmp_acquire_nested_queuing_lock( lck, gtid );
}

int
__kmp_test_nested_queuing_lock( kmp_queuing_lock_t *lck, kmp_int32 gtid )
{
    int retval;

    KMP_DEBUG_ASSERT( gtid >= 0 );

    if ( __kmp_get_queuing_lock_owner( lck ) == gtid ) {
        retval = ++lck->lk.depth_locked;
    }
    else if ( !__kmp_test_queuing_lock( lck, gtid ) ) {
        retval = 0;
    }
    else {
        KMP_MB();
        retval = lck->lk.depth_locked = 1;
        KMP_MB();
        lck->lk.owner_id = gtid + 1;
    }
    return retval;
}

static int
__kmp_test_nested_queuing_lock_with_checks( kmp_queuing_lock_t *lck,
  kmp_int32 gtid )
{
    char const * const func = "omp_test_nest_lock";
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( ! __kmp_is_queuing_lock_nestable( lck ) ) {
        KMP_FATAL( LockSimpleUsedAsNestable, func );
    }
    return __kmp_test_nested_queuing_lock( lck, gtid );
}

void
__kmp_release_nested_queuing_lock( kmp_queuing_lock_t *lck, kmp_int32 gtid )
{
    KMP_DEBUG_ASSERT( gtid >= 0 );

    KMP_MB();
    if ( --(lck->lk.depth_locked) == 0 ) {
        KMP_MB();
        lck->lk.owner_id = 0;
        __kmp_release_queuing_lock( lck, gtid );
    }
}

static void
__kmp_release_nested_queuing_lock_with_checks( kmp_queuing_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_unset_nest_lock";
    KMP_MB();  /* in case another processor initialized lock */
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( ! __kmp_is_queuing_lock_nestable( lck ) ) {
        KMP_FATAL( LockSimpleUsedAsNestable, func );
    }
    if ( __kmp_get_queuing_lock_owner( lck ) == -1 ) {
        KMP_FATAL( LockUnsettingFree, func );
    }
    if ( __kmp_get_queuing_lock_owner( lck ) != gtid ) {
        KMP_FATAL( LockUnsettingSetByAnother, func );
    }
    __kmp_release_nested_queuing_lock( lck, gtid );
}

void
__kmp_init_nested_queuing_lock( kmp_queuing_lock_t * lck )
{
    __kmp_init_queuing_lock( lck );
    lck->lk.depth_locked = 0; // >= 0 for nestable locks, -1 for simple locks
}

static void
__kmp_init_nested_queuing_lock_with_checks( kmp_queuing_lock_t * lck )
{
    __kmp_init_nested_queuing_lock( lck );
}

void
__kmp_destroy_nested_queuing_lock( kmp_queuing_lock_t *lck )
{
    __kmp_destroy_queuing_lock( lck );
    lck->lk.depth_locked = 0;
}

static void
__kmp_destroy_nested_queuing_lock_with_checks( kmp_queuing_lock_t *lck )
{
    char const * const func = "omp_destroy_nest_lock";
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( ! __kmp_is_queuing_lock_nestable( lck ) ) {
        KMP_FATAL( LockSimpleUsedAsNestable, func );
    }
    if ( __kmp_get_queuing_lock_owner( lck ) != -1 ) {
        KMP_FATAL( LockStillOwned, func );
    }
    __kmp_destroy_nested_queuing_lock( lck );
}


//
// access functions to fields which don't exist for all lock kinds.
//

static int
__kmp_is_queuing_lock_initialized( kmp_queuing_lock_t *lck )
{
    return lck == lck->lk.initialized;
}

static const ident_t *
__kmp_get_queuing_lock_location( kmp_queuing_lock_t *lck )
{
    return lck->lk.location;
}

static void
__kmp_set_queuing_lock_location( kmp_queuing_lock_t *lck, const ident_t *loc )
{
    lck->lk.location = loc;
}

static kmp_lock_flags_t
__kmp_get_queuing_lock_flags( kmp_queuing_lock_t *lck )
{
    return lck->lk.flags;
}

static void
__kmp_set_queuing_lock_flags( kmp_queuing_lock_t *lck, kmp_lock_flags_t flags )
{
    lck->lk.flags = flags;
}

#if KMP_USE_ADAPTIVE_LOCKS

/*
    RTM Adaptive locks
*/

// TODO: Use the header for intrinsics below with the compiler 13.0
//#include <immintrin.h>

// Values from the status register after failed speculation.
#define _XBEGIN_STARTED          (~0u)
#define _XABORT_EXPLICIT         (1 << 0)
#define _XABORT_RETRY            (1 << 1)
#define _XABORT_CONFLICT         (1 << 2)
#define _XABORT_CAPACITY         (1 << 3)
#define _XABORT_DEBUG            (1 << 4)
#define _XABORT_NESTED           (1 << 5)
#define _XABORT_CODE(x)          ((unsigned char)(((x) >> 24) & 0xFF))

// Aborts for which it's worth trying again immediately
#define SOFT_ABORT_MASK  (_XABORT_RETRY | _XABORT_CONFLICT | _XABORT_EXPLICIT)

#define STRINGIZE_INTERNAL(arg) #arg
#define STRINGIZE(arg) STRINGIZE_INTERNAL(arg)

// Access to RTM instructions

/*
  A version of XBegin which returns -1 on speculation, and the value of EAX on an abort.
  This is the same definition as the compiler intrinsic that will be supported at some point.
*/
static __inline int _xbegin()
{
    int res = -1;

#if KMP_OS_WINDOWS
#if KMP_ARCH_X86_64
    _asm {
        _emit 0xC7
        _emit 0xF8
        _emit 2
        _emit 0
        _emit 0
        _emit 0
        jmp   L2
        mov   res, eax
    L2:
    }
#else /* IA32 */
    _asm {
        _emit 0xC7
        _emit 0xF8
        _emit 2
        _emit 0
        _emit 0
        _emit 0
        jmp   L2
        mov   res, eax
    L2:
    }
#endif // KMP_ARCH_X86_64
#else
    /* Note that %eax must be noted as killed (clobbered), because
     * the XSR is returned in %eax(%rax) on abort.  Other register
     * values are restored, so don't need to be killed.
     *
     * We must also mark 'res' as an input and an output, since otherwise
     * 'res=-1' may be dropped as being dead, whereas we do need the
     * assignment on the successful (i.e., non-abort) path.
     */
    __asm__ volatile ("1: .byte  0xC7; .byte 0xF8;\n"
                      "   .long  1f-1b-6\n"
                      "    jmp   2f\n"
                      "1:  movl  %%eax,%0\n"
                      "2:"
                      :"+r"(res)::"memory","%eax");
#endif // KMP_OS_WINDOWS
    return res;
}

/*
  Transaction end
*/
static __inline void _xend()
{
#if KMP_OS_WINDOWS
    __asm  {
        _emit 0x0f
        _emit 0x01
        _emit 0xd5
    }
#else
    __asm__ volatile (".byte 0x0f; .byte 0x01; .byte 0xd5" :::"memory");
#endif
}

/*
  This is a macro, the argument must be a single byte constant which
  can be evaluated by the inline assembler, since it is emitted as a
  byte into the assembly code.
*/
#if KMP_OS_WINDOWS
#define _xabort(ARG)                            \
    _asm _emit 0xc6                             \
    _asm _emit 0xf8                             \
    _asm _emit ARG
#else
#define _xabort(ARG) \
    __asm__ volatile (".byte 0xC6; .byte 0xF8; .byte " STRINGIZE(ARG) :::"memory");
#endif

//
//    Statistics is collected for testing purpose
//
#if KMP_DEBUG_ADAPTIVE_LOCKS

// We accumulate speculative lock statistics when the lock is destroyed.
// We keep locks that haven't been destroyed in the liveLocks list
// so that we can grab their statistics too.
static kmp_adaptive_lock_statistics_t destroyedStats;

// To hold the list of live locks.
static kmp_adaptive_lock_info_t liveLocks;

// A lock so we can safely update the list of locks.
static kmp_bootstrap_lock_t chain_lock;

// Initialize the list of stats.
void
__kmp_init_speculative_stats()
{
    kmp_adaptive_lock_info_t *lck = &liveLocks;

    memset( ( void * ) & ( lck->stats ), 0, sizeof( lck->stats ) );
    lck->stats.next = lck;
    lck->stats.prev = lck;

    KMP_ASSERT( lck->stats.next->stats.prev == lck );
    KMP_ASSERT( lck->stats.prev->stats.next == lck );

    __kmp_init_bootstrap_lock( &chain_lock );

}

// Insert the lock into the circular list
static void
__kmp_remember_lock( kmp_adaptive_lock_info_t * lck )
{
    __kmp_acquire_bootstrap_lock( &chain_lock );

    lck->stats.next = liveLocks.stats.next;
    lck->stats.prev = &liveLocks;

    liveLocks.stats.next = lck;
    lck->stats.next->stats.prev  = lck;

    KMP_ASSERT( lck->stats.next->stats.prev == lck );
    KMP_ASSERT( lck->stats.prev->stats.next == lck );

    __kmp_release_bootstrap_lock( &chain_lock );
}

static void
__kmp_forget_lock( kmp_adaptive_lock_info_t * lck )
{
    KMP_ASSERT( lck->stats.next->stats.prev == lck );
    KMP_ASSERT( lck->stats.prev->stats.next == lck );

    kmp_adaptive_lock_info_t * n = lck->stats.next;
    kmp_adaptive_lock_info_t * p = lck->stats.prev;

    n->stats.prev = p;
    p->stats.next = n;
}

static void
__kmp_zero_speculative_stats( kmp_adaptive_lock_info_t * lck )
{
    memset( ( void * )&lck->stats, 0, sizeof( lck->stats ) );
    __kmp_remember_lock( lck );
}

static void
__kmp_add_stats( kmp_adaptive_lock_statistics_t * t, kmp_adaptive_lock_info_t * lck )
{
    kmp_adaptive_lock_statistics_t volatile *s = &lck->stats;

    t->nonSpeculativeAcquireAttempts += lck->acquire_attempts;
    t->successfulSpeculations += s->successfulSpeculations;
    t->hardFailedSpeculations += s->hardFailedSpeculations;
    t->softFailedSpeculations += s->softFailedSpeculations;
    t->nonSpeculativeAcquires += s->nonSpeculativeAcquires;
    t->lemmingYields          += s->lemmingYields;
}

static void
__kmp_accumulate_speculative_stats( kmp_adaptive_lock_info_t * lck)
{
    kmp_adaptive_lock_statistics_t *t = &destroyedStats;

    __kmp_acquire_bootstrap_lock( &chain_lock );

    __kmp_add_stats( &destroyedStats, lck );
    __kmp_forget_lock( lck );

    __kmp_release_bootstrap_lock( &chain_lock );
}

static float
percent (kmp_uint32 count, kmp_uint32 total)
{
    return (total == 0) ? 0.0: (100.0 * count)/total;
}

static
FILE * __kmp_open_stats_file()
{
    if (strcmp (__kmp_speculative_statsfile, "-") == 0)
        return stdout;

    size_t buffLen = strlen( __kmp_speculative_statsfile ) + 20;
    char buffer[buffLen];
    snprintf (&buffer[0], buffLen, __kmp_speculative_statsfile,
      (kmp_int32)getpid());
    FILE * result = fopen(&buffer[0], "w");

    // Maybe we should issue a warning here...
    return result ? result : stdout;
}

void
__kmp_print_speculative_stats()
{
    if (__kmp_user_lock_kind != lk_adaptive)
        return;

    FILE * statsFile = __kmp_open_stats_file();

    kmp_adaptive_lock_statistics_t total = destroyedStats;
    kmp_adaptive_lock_info_t *lck;

    for (lck = liveLocks.stats.next; lck != &liveLocks; lck = lck->stats.next) {
        __kmp_add_stats( &total, lck );
    }
    kmp_adaptive_lock_statistics_t *t = &total;
    kmp_uint32 totalSections     = t->nonSpeculativeAcquires + t->successfulSpeculations;
    kmp_uint32 totalSpeculations = t->successfulSpeculations + t->hardFailedSpeculations +
                                   t->softFailedSpeculations;

    fprintf ( statsFile, "Speculative lock statistics (all approximate!)\n");
    fprintf ( statsFile, " Lock parameters: \n"
             "   max_soft_retries               : %10d\n"
             "   max_badness                    : %10d\n",
             __kmp_adaptive_backoff_params.max_soft_retries,
             __kmp_adaptive_backoff_params.max_badness);
    fprintf( statsFile, " Non-speculative acquire attempts : %10d\n", t->nonSpeculativeAcquireAttempts );
    fprintf( statsFile, " Total critical sections          : %10d\n", totalSections );
    fprintf( statsFile, " Successful speculations          : %10d (%5.1f%%)\n",
             t->successfulSpeculations, percent( t->successfulSpeculations, totalSections ) );
    fprintf( statsFile, " Non-speculative acquires         : %10d (%5.1f%%)\n",
             t->nonSpeculativeAcquires, percent( t->nonSpeculativeAcquires, totalSections ) );
    fprintf( statsFile, " Lemming yields                   : %10d\n\n", t->lemmingYields );

    fprintf( statsFile, " Speculative acquire attempts     : %10d\n", totalSpeculations );
    fprintf( statsFile, " Successes                        : %10d (%5.1f%%)\n",
             t->successfulSpeculations, percent( t->successfulSpeculations, totalSpeculations ) );
    fprintf( statsFile, " Soft failures                    : %10d (%5.1f%%)\n",
             t->softFailedSpeculations, percent( t->softFailedSpeculations, totalSpeculations ) );
    fprintf( statsFile, " Hard failures                    : %10d (%5.1f%%)\n",
             t->hardFailedSpeculations, percent( t->hardFailedSpeculations, totalSpeculations ) );

    if (statsFile != stdout)
        fclose( statsFile );
}

# define KMP_INC_STAT(lck,stat) ( lck->lk.adaptive.stats.stat++ )
#else
# define KMP_INC_STAT(lck,stat)

#endif // KMP_DEBUG_ADAPTIVE_LOCKS

static inline bool
__kmp_is_unlocked_queuing_lock( kmp_queuing_lock_t *lck )
{
    // It is enough to check that the head_id is zero.
    // We don't also need to check the tail.
    bool res = lck->lk.head_id == 0;

    // We need a fence here, since we must ensure that no memory operations
    // from later in this thread float above that read.
#if KMP_COMPILER_ICC
    _mm_mfence();
#else
    __sync_synchronize();
#endif

    return res;
}

// Functions for manipulating the badness
static __inline void
__kmp_update_badness_after_success( kmp_adaptive_lock_t *lck )
{
    // Reset the badness to zero so we eagerly try to speculate again
    lck->lk.adaptive.badness = 0;
    KMP_INC_STAT(lck,successfulSpeculations);
}

// Create a bit mask with one more set bit.
static __inline void
__kmp_step_badness( kmp_adaptive_lock_t *lck )
{
    kmp_uint32 newBadness = ( lck->lk.adaptive.badness << 1 ) | 1;
    if ( newBadness > lck->lk.adaptive.max_badness) {
        return;
    } else {
        lck->lk.adaptive.badness = newBadness;
    }
}

// Check whether speculation should be attempted.
static __inline int
__kmp_should_speculate( kmp_adaptive_lock_t *lck, kmp_int32 gtid )
{
    kmp_uint32 badness = lck->lk.adaptive.badness;
    kmp_uint32 attempts= lck->lk.adaptive.acquire_attempts;
    int res = (attempts & badness) == 0;
    return res;
}

// Attempt to acquire only the speculative lock.
// Does not back off to the non-speculative lock.
//
static int
__kmp_test_adaptive_lock_only( kmp_adaptive_lock_t * lck, kmp_int32 gtid )
{
    int retries = lck->lk.adaptive.max_soft_retries;

    // We don't explicitly count the start of speculation, rather we record
    // the results (success, hard fail, soft fail). The sum of all of those
    // is the total number of times we started speculation since all
    // speculations must end one of those ways.
    do
    {
        kmp_uint32 status = _xbegin();
        // Switch this in to disable actual speculation but exercise
        // at least some of the rest of the code. Useful for debugging...
        // kmp_uint32 status = _XABORT_NESTED;

        if (status == _XBEGIN_STARTED )
        { /* We have successfully started speculation
           * Check that no-one acquired the lock for real between when we last looked
           * and now. This also gets the lock cache line into our read-set,
           * which we need so that we'll abort if anyone later claims it for real.
           */
            if (! __kmp_is_unlocked_queuing_lock( GET_QLK_PTR(lck) ) )
            {
                // Lock is now visibly acquired, so someone beat us to it.
                // Abort the transaction so we'll restart from _xbegin with the
                // failure status.
                _xabort(0x01)
                KMP_ASSERT2( 0, "should not get here" );
            }
            return 1;   // Lock has been acquired (speculatively)
        } else {
            // We have aborted, update the statistics
            if ( status & SOFT_ABORT_MASK)
            {
                KMP_INC_STAT(lck,softFailedSpeculations);
                // and loop round to retry.
            }
            else
            {
                KMP_INC_STAT(lck,hardFailedSpeculations);
                // Give up if we had a hard failure.
                break;
            }
        }
    }  while( retries-- ); // Loop while we have retries, and didn't fail hard.

    // Either we had a hard failure or we didn't succeed softly after
    // the full set of attempts, so back off the badness.
    __kmp_step_badness( lck );
    return 0;
}

// Attempt to acquire the speculative lock, or back off to the non-speculative one
// if the speculative lock cannot be acquired.
// We can succeed speculatively, non-speculatively, or fail.
static int
__kmp_test_adaptive_lock( kmp_adaptive_lock_t *lck, kmp_int32 gtid )
{
    // First try to acquire the lock speculatively
    if ( __kmp_should_speculate( lck, gtid ) && __kmp_test_adaptive_lock_only( lck, gtid ) )
        return 1;

    // Speculative acquisition failed, so try to acquire it non-speculatively.
    // Count the non-speculative acquire attempt
    lck->lk.adaptive.acquire_attempts++;

    // Use base, non-speculative lock.
    if ( __kmp_test_queuing_lock( GET_QLK_PTR(lck), gtid ) )
    {
        KMP_INC_STAT(lck,nonSpeculativeAcquires);
        return 1;       // Lock is acquired (non-speculatively)
    }
    else
    {
        return 0;       // Failed to acquire the lock, it's already visibly locked.
    }
}

static int
__kmp_test_adaptive_lock_with_checks( kmp_adaptive_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_test_lock";
    if ( lck->lk.qlk.initialized != GET_QLK_PTR(lck) ) {
        KMP_FATAL( LockIsUninitialized, func );
    }

    int retval = __kmp_test_adaptive_lock( lck, gtid );

    if ( retval ) {
        lck->lk.qlk.owner_id = gtid + 1;
    }
    return retval;
}

// Block until we can acquire a speculative, adaptive lock.
// We check whether we should be trying to speculate.
// If we should be, we check the real lock to see if it is free,
// and, if not, pause without attempting to acquire it until it is.
// Then we try the speculative acquire.
// This means that although we suffer from lemmings a little (
// because all we can't acquire the lock speculatively until
// the queue of threads waiting has cleared), we don't get into a
// state where we can never acquire the lock speculatively (because we
// force the queue to clear by preventing new arrivals from entering the
// queue).
// This does mean that when we're trying to break lemmings, the lock
// is no longer fair. However OpenMP makes no guarantee that its
// locks are fair, so this isn't a real problem.
static void
__kmp_acquire_adaptive_lock( kmp_adaptive_lock_t * lck, kmp_int32 gtid )
{
    if ( __kmp_should_speculate( lck, gtid ) )
    {
        if ( __kmp_is_unlocked_queuing_lock( GET_QLK_PTR(lck) ) )
        {
            if ( __kmp_test_adaptive_lock_only( lck , gtid ) )
                return;
            // We tried speculation and failed, so give up.
        }
        else
        {
            // We can't try speculation until the lock is free, so we
            // pause here (without suspending on the queueing lock,
            // to allow it to drain, then try again.
            // All other threads will also see the same result for
            // shouldSpeculate, so will be doing the same if they
            // try to claim the lock from now on.
            while ( ! __kmp_is_unlocked_queuing_lock( GET_QLK_PTR(lck) ) )
            {
                KMP_INC_STAT(lck,lemmingYields);
                __kmp_yield (TRUE);
            }

            if ( __kmp_test_adaptive_lock_only( lck, gtid ) )
                return;
        }
    }

    // Speculative acquisition failed, so acquire it non-speculatively.
    // Count the non-speculative acquire attempt
    lck->lk.adaptive.acquire_attempts++;

    __kmp_acquire_queuing_lock_timed_template<FALSE>( GET_QLK_PTR(lck), gtid );
    // We have acquired the base lock, so count that.
    KMP_INC_STAT(lck,nonSpeculativeAcquires );
}

static void
__kmp_acquire_adaptive_lock_with_checks( kmp_adaptive_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_set_lock";
    if ( lck->lk.qlk.initialized != GET_QLK_PTR(lck) ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( __kmp_get_queuing_lock_owner( GET_QLK_PTR(lck) ) == gtid ) {
        KMP_FATAL( LockIsAlreadyOwned, func );
    }

    __kmp_acquire_adaptive_lock( lck, gtid );

    lck->lk.qlk.owner_id = gtid + 1;
}

static void
__kmp_release_adaptive_lock( kmp_adaptive_lock_t *lck, kmp_int32 gtid )
{
    if ( __kmp_is_unlocked_queuing_lock( GET_QLK_PTR(lck) ) )
    {   // If the lock doesn't look claimed we must be speculating.
        // (Or the user's code is buggy and they're releasing without locking;
        // if we had XTEST we'd be able to check that case...)
        _xend();        // Exit speculation
        __kmp_update_badness_after_success( lck );
    }
    else
    {   // Since the lock *is* visibly locked we're not speculating,
        // so should use the underlying lock's release scheme.
        __kmp_release_queuing_lock( GET_QLK_PTR(lck), gtid );
    }
}

static void
__kmp_release_adaptive_lock_with_checks( kmp_adaptive_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_unset_lock";
    KMP_MB();  /* in case another processor initialized lock */
    if ( lck->lk.qlk.initialized != GET_QLK_PTR(lck) ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( __kmp_get_queuing_lock_owner( GET_QLK_PTR(lck) ) == -1 ) {
        KMP_FATAL( LockUnsettingFree, func );
    }
    if ( __kmp_get_queuing_lock_owner( GET_QLK_PTR(lck) ) != gtid ) {
        KMP_FATAL( LockUnsettingSetByAnother, func );
    }
    lck->lk.qlk.owner_id = 0;
    __kmp_release_adaptive_lock( lck, gtid );
}

static void
__kmp_init_adaptive_lock( kmp_adaptive_lock_t *lck )
{
    __kmp_init_queuing_lock( GET_QLK_PTR(lck) );
    lck->lk.adaptive.badness = 0;
    lck->lk.adaptive.acquire_attempts = 0; //nonSpeculativeAcquireAttempts = 0;
    lck->lk.adaptive.max_soft_retries = __kmp_adaptive_backoff_params.max_soft_retries;
    lck->lk.adaptive.max_badness      = __kmp_adaptive_backoff_params.max_badness;
#if KMP_DEBUG_ADAPTIVE_LOCKS
    __kmp_zero_speculative_stats( &lck->lk.adaptive );
#endif
    KA_TRACE(1000, ("__kmp_init_adaptive_lock: lock %p initialized\n", lck));
}

static void
__kmp_init_adaptive_lock_with_checks( kmp_adaptive_lock_t * lck )
{
    __kmp_init_adaptive_lock( lck );
}

static void
__kmp_destroy_adaptive_lock( kmp_adaptive_lock_t *lck )
{
#if KMP_DEBUG_ADAPTIVE_LOCKS
    __kmp_accumulate_speculative_stats( &lck->lk.adaptive );
#endif
    __kmp_destroy_queuing_lock (GET_QLK_PTR(lck));
    // Nothing needed for the speculative part.
}

static void
__kmp_destroy_adaptive_lock_with_checks( kmp_adaptive_lock_t *lck )
{
    char const * const func = "omp_destroy_lock";
    if ( lck->lk.qlk.initialized != GET_QLK_PTR(lck) ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( __kmp_get_queuing_lock_owner( GET_QLK_PTR(lck) ) != -1 ) {
        KMP_FATAL( LockStillOwned, func );
    }
    __kmp_destroy_adaptive_lock( lck );
}


#endif // KMP_USE_ADAPTIVE_LOCKS


/* ------------------------------------------------------------------------ */
/* DRDPA ticket locks                                                */
/* "DRDPA" means Dynamically Reconfigurable Distributed Polling Area */

static kmp_int32
__kmp_get_drdpa_lock_owner( kmp_drdpa_lock_t *lck )
{
    return TCR_4( lck->lk.owner_id ) - 1;
}

static inline bool
__kmp_is_drdpa_lock_nestable( kmp_drdpa_lock_t *lck )
{
    return lck->lk.depth_locked != -1;
}

__forceinline static void
__kmp_acquire_drdpa_lock_timed_template( kmp_drdpa_lock_t *lck, kmp_int32 gtid )
{
    kmp_uint64 ticket = KMP_TEST_THEN_INC64((kmp_int64 *)&lck->lk.next_ticket);
    kmp_uint64 mask = TCR_8(lck->lk.mask);              // volatile load
    volatile struct kmp_base_drdpa_lock::kmp_lock_poll *polls
      = (volatile struct kmp_base_drdpa_lock::kmp_lock_poll *)
      TCR_PTR(lck->lk.polls);                           // volatile load

#ifdef USE_LOCK_PROFILE
    if (TCR_8(polls[ticket & mask].poll) != ticket)
        __kmp_printf("LOCK CONTENTION: %p\n", lck);
    /* else __kmp_printf( "." );*/
#endif /* USE_LOCK_PROFILE */

    //
    // Now spin-wait, but reload the polls pointer and mask, in case the
    // polling area has been reconfigured.  Unless it is reconfigured, the
    // reloads stay in L1 cache and are cheap.
    //
    // Keep this code in sync with KMP_WAIT_YIELD, in kmp_dispatch.c !!!
    //
    // The current implementation of KMP_WAIT_YIELD doesn't allow for mask
    // and poll to be re-read every spin iteration.
    //
    kmp_uint32 spins;

    KMP_FSYNC_PREPARE(lck);
    KMP_INIT_YIELD(spins);
    while (TCR_8(polls[ticket & mask]).poll < ticket) { // volatile load
        // If we are oversubscribed,
        // or have waited a bit (and KMP_LIBRARY=turnaround), then yield.
        // CPU Pause is in the macros for yield.
        //
        KMP_YIELD(TCR_4(__kmp_nth)
          > (__kmp_avail_proc ? __kmp_avail_proc : __kmp_xproc));
        KMP_YIELD_SPIN(spins);

        // Re-read the mask and the poll pointer from the lock structure.
        //
        // Make certain that "mask" is read before "polls" !!!
        //
        // If another thread picks reconfigures the polling area and updates
        // their values, and we get the new value of mask and the old polls
        // pointer, we could access memory beyond the end of the old polling
        // area.
        //
        mask = TCR_8(lck->lk.mask);                     // volatile load
        polls = (volatile struct kmp_base_drdpa_lock::kmp_lock_poll *)
          TCR_PTR(lck->lk.polls);                       // volatile load
    }

    //
    // Critical section starts here
    //
    KMP_FSYNC_ACQUIRED(lck);
    KA_TRACE(1000, ("__kmp_acquire_drdpa_lock: ticket #%lld acquired lock %p\n",
      ticket, lck));
    lck->lk.now_serving = ticket;                       // non-volatile store

    //
    // Deallocate a garbage polling area if we know that we are the last
    // thread that could possibly access it.
    //
    // The >= check is in case __kmp_test_drdpa_lock() allocated the cleanup
    // ticket.
    //
    if ((lck->lk.old_polls != NULL) && (ticket >= lck->lk.cleanup_ticket)) {
        __kmp_free((void *)lck->lk.old_polls);
        lck->lk.old_polls = NULL;
        lck->lk.cleanup_ticket = 0;
    }

    //
    // Check to see if we should reconfigure the polling area.
    // If there is still a garbage polling area to be deallocated from a
    // previous reconfiguration, let a later thread reconfigure it.
    //
    if (lck->lk.old_polls == NULL) {
        bool reconfigure = false;
        volatile struct kmp_base_drdpa_lock::kmp_lock_poll *old_polls = polls;
        kmp_uint32 num_polls = TCR_4(lck->lk.num_polls);

        if (TCR_4(__kmp_nth)
          > (__kmp_avail_proc ? __kmp_avail_proc : __kmp_xproc)) {
            //
            // We are in oversubscription mode.  Contract the polling area
            // down to a single location, if that hasn't been done already.
            //
            if (num_polls > 1) {
                reconfigure = true;
                num_polls = TCR_4(lck->lk.num_polls);
                mask = 0;
                num_polls = 1;
                polls = (volatile struct kmp_base_drdpa_lock::kmp_lock_poll *)
                  __kmp_allocate(num_polls * sizeof(*polls));
                polls[0].poll = ticket;
            }
        }
        else {
            //
            // We are in under/fully subscribed mode.  Check the number of
            // threads waiting on the lock.  The size of the polling area
            // should be at least the number of threads waiting.
            //
            kmp_uint64 num_waiting = TCR_8(lck->lk.next_ticket) - ticket - 1;
            if (num_waiting > num_polls) {
                kmp_uint32 old_num_polls = num_polls;
                reconfigure = true;
                do {
                    mask = (mask << 1) | 1;
                    num_polls *= 2;
                } while (num_polls <= num_waiting);

                //
                // Allocate the new polling area, and copy the relevant portion
                // of the old polling area to the new area.  __kmp_allocate()
                // zeroes the memory it allocates, and most of the old area is
                // just zero padding, so we only copy the release counters.
                //
                polls = (volatile struct kmp_base_drdpa_lock::kmp_lock_poll *)
                  __kmp_allocate(num_polls * sizeof(*polls));
                kmp_uint32 i;
                for (i = 0; i < old_num_polls; i++) {
                    polls[i].poll = old_polls[i].poll;
                }
            }
        }

        if (reconfigure) {
            //
            // Now write the updated fields back to the lock structure.
            //
            // Make certain that "polls" is written before "mask" !!!
            //
            // If another thread picks up the new value of mask and the old
            // polls pointer , it could access memory beyond the end of the
            // old polling area.
            //
            // On x86, we need memory fences.
            //
            KA_TRACE(1000, ("__kmp_acquire_drdpa_lock: ticket #%lld reconfiguring lock %p to %d polls\n",
              ticket, lck, num_polls));

            lck->lk.old_polls = old_polls;              // non-volatile store
            lck->lk.polls = polls;                      // volatile store

            KMP_MB();

            lck->lk.num_polls = num_polls;              // non-volatile store
            lck->lk.mask = mask;                        // volatile store

            KMP_MB();

            //
            // Only after the new polling area and mask have been flushed
            // to main memory can we update the cleanup ticket field.
            //
            // volatile load / non-volatile store
            //
            lck->lk.cleanup_ticket = TCR_8(lck->lk.next_ticket);
        }
    }
}

void
__kmp_acquire_drdpa_lock( kmp_drdpa_lock_t *lck, kmp_int32 gtid )
{
    __kmp_acquire_drdpa_lock_timed_template( lck, gtid );
}

static void
__kmp_acquire_drdpa_lock_with_checks( kmp_drdpa_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_set_lock";
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( __kmp_is_drdpa_lock_nestable( lck ) ) {
        KMP_FATAL( LockNestableUsedAsSimple, func );
    }
    if ( ( gtid >= 0 ) && ( __kmp_get_drdpa_lock_owner( lck ) == gtid ) ) {
        KMP_FATAL( LockIsAlreadyOwned, func );
    }

    __kmp_acquire_drdpa_lock( lck, gtid );

    lck->lk.owner_id = gtid + 1;
}

int
__kmp_test_drdpa_lock( kmp_drdpa_lock_t *lck, kmp_int32 gtid )
{
    //
    // First get a ticket, then read the polls pointer and the mask.
    // The polls pointer must be read before the mask!!! (See above)
    //
    kmp_uint64 ticket = TCR_8(lck->lk.next_ticket);     // volatile load
    volatile struct kmp_base_drdpa_lock::kmp_lock_poll *polls
      = (volatile struct kmp_base_drdpa_lock::kmp_lock_poll *)
      TCR_PTR(lck->lk.polls);                           // volatile load
    kmp_uint64 mask = TCR_8(lck->lk.mask);              // volatile load
    if (TCR_8(polls[ticket & mask].poll) == ticket) {
        kmp_uint64 next_ticket = ticket + 1;
        if (KMP_COMPARE_AND_STORE_ACQ64((kmp_int64 *)&lck->lk.next_ticket,
          ticket, next_ticket)) {
            KMP_FSYNC_ACQUIRED(lck);
            KA_TRACE(1000, ("__kmp_test_drdpa_lock: ticket #%lld acquired lock %p\n",
               ticket, lck));
            lck->lk.now_serving = ticket;               // non-volatile store

            //
            // Since no threads are waiting, there is no possibility that
            // we would want to reconfigure the polling area.  We might
            // have the cleanup ticket value (which says that it is now
            // safe to deallocate old_polls), but we'll let a later thread
            // which calls __kmp_acquire_lock do that - this routine
            // isn't supposed to block, and we would risk blocks if we
            // called __kmp_free() to do the deallocation.
            //
            return TRUE;
        }
    }
    return FALSE;
}

static int
__kmp_test_drdpa_lock_with_checks( kmp_drdpa_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_test_lock";
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( __kmp_is_drdpa_lock_nestable( lck ) ) {
        KMP_FATAL( LockNestableUsedAsSimple, func );
    }

    int retval = __kmp_test_drdpa_lock( lck, gtid );

    if ( retval ) {
        lck->lk.owner_id = gtid + 1;
    }
    return retval;
}

void
__kmp_release_drdpa_lock( kmp_drdpa_lock_t *lck, kmp_int32 gtid )
{
    //
    // Read the ticket value from the lock data struct, then the polls
    // pointer and the mask.  The polls pointer must be read before the
    // mask!!! (See above)
    //
    kmp_uint64 ticket = lck->lk.now_serving + 1;        // non-volatile load
    volatile struct kmp_base_drdpa_lock::kmp_lock_poll *polls
      = (volatile struct kmp_base_drdpa_lock::kmp_lock_poll *)
      TCR_PTR(lck->lk.polls);                           // volatile load
    kmp_uint64 mask = TCR_8(lck->lk.mask);              // volatile load
    KA_TRACE(1000, ("__kmp_release_drdpa_lock: ticket #%lld released lock %p\n",
       ticket - 1, lck));
    KMP_FSYNC_RELEASING(lck);
    KMP_ST_REL64(&(polls[ticket & mask].poll), ticket); // volatile store
}

static void
__kmp_release_drdpa_lock_with_checks( kmp_drdpa_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_unset_lock";
    KMP_MB();  /* in case another processor initialized lock */
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( __kmp_is_drdpa_lock_nestable( lck ) ) {
        KMP_FATAL( LockNestableUsedAsSimple, func );
    }
    if ( __kmp_get_drdpa_lock_owner( lck ) == -1 ) {
        KMP_FATAL( LockUnsettingFree, func );
    }
    if ( ( gtid >= 0 ) && ( __kmp_get_drdpa_lock_owner( lck ) >= 0 )
      && ( __kmp_get_drdpa_lock_owner( lck ) != gtid ) ) {
        KMP_FATAL( LockUnsettingSetByAnother, func );
    }
    lck->lk.owner_id = 0;
    __kmp_release_drdpa_lock( lck, gtid );
}

void
__kmp_init_drdpa_lock( kmp_drdpa_lock_t *lck )
{
    lck->lk.location = NULL;
    lck->lk.mask = 0;
    lck->lk.num_polls = 1;
    lck->lk.polls = (volatile struct kmp_base_drdpa_lock::kmp_lock_poll *)
      __kmp_allocate(lck->lk.num_polls * sizeof(*(lck->lk.polls)));
    lck->lk.cleanup_ticket = 0;
    lck->lk.old_polls = NULL;
    lck->lk.next_ticket = 0;
    lck->lk.now_serving = 0;
    lck->lk.owner_id = 0;      // no thread owns the lock.
    lck->lk.depth_locked = -1; // >= 0 for nestable locks, -1 for simple locks.
    lck->lk.initialized = lck;

    KA_TRACE(1000, ("__kmp_init_drdpa_lock: lock %p initialized\n", lck));
}

static void
__kmp_init_drdpa_lock_with_checks( kmp_drdpa_lock_t * lck )
{
    __kmp_init_drdpa_lock( lck );
}

void
__kmp_destroy_drdpa_lock( kmp_drdpa_lock_t *lck )
{
    lck->lk.initialized = NULL;
    lck->lk.location    = NULL;
    if (lck->lk.polls != NULL) {
        __kmp_free((void *)lck->lk.polls);
        lck->lk.polls = NULL;
    }
    if (lck->lk.old_polls != NULL) {
        __kmp_free((void *)lck->lk.old_polls);
        lck->lk.old_polls = NULL;
    }
    lck->lk.mask = 0;
    lck->lk.num_polls = 0;
    lck->lk.cleanup_ticket = 0;
    lck->lk.next_ticket = 0;
    lck->lk.now_serving = 0;
    lck->lk.owner_id = 0;
    lck->lk.depth_locked = -1;
}

static void
__kmp_destroy_drdpa_lock_with_checks( kmp_drdpa_lock_t *lck )
{
    char const * const func = "omp_destroy_lock";
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( __kmp_is_drdpa_lock_nestable( lck ) ) {
        KMP_FATAL( LockNestableUsedAsSimple, func );
    }
    if ( __kmp_get_drdpa_lock_owner( lck ) != -1 ) {
        KMP_FATAL( LockStillOwned, func );
    }
    __kmp_destroy_drdpa_lock( lck );
}


//
// nested drdpa ticket locks
//

void
__kmp_acquire_nested_drdpa_lock( kmp_drdpa_lock_t *lck, kmp_int32 gtid )
{
    KMP_DEBUG_ASSERT( gtid >= 0 );

    if ( __kmp_get_drdpa_lock_owner( lck ) == gtid ) {
        lck->lk.depth_locked += 1;
    }
    else {
        __kmp_acquire_drdpa_lock_timed_template( lck, gtid );
        KMP_MB();
        lck->lk.depth_locked = 1;
        KMP_MB();
        lck->lk.owner_id = gtid + 1;
    }
}

static void
__kmp_acquire_nested_drdpa_lock_with_checks( kmp_drdpa_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_set_nest_lock";
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( ! __kmp_is_drdpa_lock_nestable( lck ) ) {
        KMP_FATAL( LockSimpleUsedAsNestable, func );
    }
    __kmp_acquire_nested_drdpa_lock( lck, gtid );
}

int
__kmp_test_nested_drdpa_lock( kmp_drdpa_lock_t *lck, kmp_int32 gtid )
{
    int retval;

    KMP_DEBUG_ASSERT( gtid >= 0 );

    if ( __kmp_get_drdpa_lock_owner( lck ) == gtid ) {
        retval = ++lck->lk.depth_locked;
    }
    else if ( !__kmp_test_drdpa_lock( lck, gtid ) ) {
        retval = 0;
    }
    else {
        KMP_MB();
        retval = lck->lk.depth_locked = 1;
        KMP_MB();
        lck->lk.owner_id = gtid + 1;
    }
    return retval;
}

static int
__kmp_test_nested_drdpa_lock_with_checks( kmp_drdpa_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_test_nest_lock";
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( ! __kmp_is_drdpa_lock_nestable( lck ) ) {
        KMP_FATAL( LockSimpleUsedAsNestable, func );
    }
    return __kmp_test_nested_drdpa_lock( lck, gtid );
}

void
__kmp_release_nested_drdpa_lock( kmp_drdpa_lock_t *lck, kmp_int32 gtid )
{
    KMP_DEBUG_ASSERT( gtid >= 0 );

    KMP_MB();
    if ( --(lck->lk.depth_locked) == 0 ) {
        KMP_MB();
        lck->lk.owner_id = 0;
        __kmp_release_drdpa_lock( lck, gtid );
    }
}

static void
__kmp_release_nested_drdpa_lock_with_checks( kmp_drdpa_lock_t *lck, kmp_int32 gtid )
{
    char const * const func = "omp_unset_nest_lock";
    KMP_MB();  /* in case another processor initialized lock */
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( ! __kmp_is_drdpa_lock_nestable( lck ) ) {
        KMP_FATAL( LockSimpleUsedAsNestable, func );
    }
    if ( __kmp_get_drdpa_lock_owner( lck ) == -1 ) {
        KMP_FATAL( LockUnsettingFree, func );
    }
    if ( __kmp_get_drdpa_lock_owner( lck ) != gtid ) {
        KMP_FATAL( LockUnsettingSetByAnother, func );
    }
    __kmp_release_nested_drdpa_lock( lck, gtid );
}

void
__kmp_init_nested_drdpa_lock( kmp_drdpa_lock_t * lck )
{
    __kmp_init_drdpa_lock( lck );
    lck->lk.depth_locked = 0; // >= 0 for nestable locks, -1 for simple locks
}

static void
__kmp_init_nested_drdpa_lock_with_checks( kmp_drdpa_lock_t * lck )
{
    __kmp_init_nested_drdpa_lock( lck );
}

void
__kmp_destroy_nested_drdpa_lock( kmp_drdpa_lock_t *lck )
{
    __kmp_destroy_drdpa_lock( lck );
    lck->lk.depth_locked = 0;
}

static void
__kmp_destroy_nested_drdpa_lock_with_checks( kmp_drdpa_lock_t *lck )
{
    char const * const func = "omp_destroy_nest_lock";
    if ( lck->lk.initialized != lck ) {
        KMP_FATAL( LockIsUninitialized, func );
    }
    if ( ! __kmp_is_drdpa_lock_nestable( lck ) ) {
        KMP_FATAL( LockSimpleUsedAsNestable, func );
    }
    if ( __kmp_get_drdpa_lock_owner( lck ) != -1 ) {
        KMP_FATAL( LockStillOwned, func );
    }
    __kmp_destroy_nested_drdpa_lock( lck );
}


//
// access functions to fields which don't exist for all lock kinds.
//

static int
__kmp_is_drdpa_lock_initialized( kmp_drdpa_lock_t *lck )
{
    return lck == lck->lk.initialized;
}

static const ident_t *
__kmp_get_drdpa_lock_location( kmp_drdpa_lock_t *lck )
{
    return lck->lk.location;
}

static void
__kmp_set_drdpa_lock_location( kmp_drdpa_lock_t *lck, const ident_t *loc )
{
    lck->lk.location = loc;
}

static kmp_lock_flags_t
__kmp_get_drdpa_lock_flags( kmp_drdpa_lock_t *lck )
{
    return lck->lk.flags;
}

static void
__kmp_set_drdpa_lock_flags( kmp_drdpa_lock_t *lck, kmp_lock_flags_t flags )
{
    lck->lk.flags = flags;
}

/* ------------------------------------------------------------------------ */
/* user locks
 *
 * They are implemented as a table of function pointers which are set to the
 * lock functions of the appropriate kind, once that has been determined.
 */

enum kmp_lock_kind __kmp_user_lock_kind = lk_default;

size_t __kmp_base_user_lock_size = 0;
size_t __kmp_user_lock_size = 0;

kmp_int32 ( *__kmp_get_user_lock_owner_ )( kmp_user_lock_p lck ) = NULL;
void ( *__kmp_acquire_user_lock_with_checks_ )( kmp_user_lock_p lck, kmp_int32 gtid ) = NULL;

int ( *__kmp_test_user_lock_with_checks_ )( kmp_user_lock_p lck, kmp_int32 gtid ) = NULL;
void ( *__kmp_release_user_lock_with_checks_ )( kmp_user_lock_p lck, kmp_int32 gtid ) = NULL;
void ( *__kmp_init_user_lock_with_checks_ )( kmp_user_lock_p lck ) = NULL;
void ( *__kmp_destroy_user_lock_ )( kmp_user_lock_p lck ) = NULL;
void ( *__kmp_destroy_user_lock_with_checks_ )( kmp_user_lock_p lck ) = NULL;
void ( *__kmp_acquire_nested_user_lock_with_checks_ )( kmp_user_lock_p lck, kmp_int32 gtid ) = NULL;

int ( *__kmp_test_nested_user_lock_with_checks_ )( kmp_user_lock_p lck, kmp_int32 gtid ) = NULL;
void ( *__kmp_release_nested_user_lock_with_checks_ )( kmp_user_lock_p lck, kmp_int32 gtid ) = NULL;
void ( *__kmp_init_nested_user_lock_with_checks_ )( kmp_user_lock_p lck ) = NULL;
void ( *__kmp_destroy_nested_user_lock_with_checks_ )( kmp_user_lock_p lck ) = NULL;

int ( *__kmp_is_user_lock_initialized_ )( kmp_user_lock_p lck ) = NULL;
const ident_t * ( *__kmp_get_user_lock_location_ )( kmp_user_lock_p lck ) = NULL;
void ( *__kmp_set_user_lock_location_ )( kmp_user_lock_p lck, const ident_t *loc ) = NULL;
kmp_lock_flags_t ( *__kmp_get_user_lock_flags_ )( kmp_user_lock_p lck ) = NULL;
void ( *__kmp_set_user_lock_flags_ )( kmp_user_lock_p lck, kmp_lock_flags_t flags ) = NULL;

void __kmp_set_user_lock_vptrs( kmp_lock_kind_t user_lock_kind )
{
    switch ( user_lock_kind ) {
        case lk_default:
        default:
        KMP_ASSERT( 0 );

        case lk_tas: {
            __kmp_base_user_lock_size = sizeof( kmp_base_tas_lock_t );
            __kmp_user_lock_size = sizeof( kmp_tas_lock_t );

            __kmp_get_user_lock_owner_ =
              ( kmp_int32 ( * )( kmp_user_lock_p ) )
              ( &__kmp_get_tas_lock_owner );

            if ( __kmp_env_consistency_check ) {
                KMP_BIND_USER_LOCK_WITH_CHECKS(tas);
                KMP_BIND_NESTED_USER_LOCK_WITH_CHECKS(tas);
            }
            else {
                KMP_BIND_USER_LOCK(tas);
                KMP_BIND_NESTED_USER_LOCK(tas);
            }

            __kmp_destroy_user_lock_ =
              ( void ( * )( kmp_user_lock_p ) )
              ( &__kmp_destroy_tas_lock );

             __kmp_is_user_lock_initialized_ =
               ( int ( * )( kmp_user_lock_p ) ) NULL;

             __kmp_get_user_lock_location_ =
               ( const ident_t * ( * )( kmp_user_lock_p ) ) NULL;

             __kmp_set_user_lock_location_ =
               ( void ( * )( kmp_user_lock_p, const ident_t * ) ) NULL;

             __kmp_get_user_lock_flags_ =
               ( kmp_lock_flags_t ( * )( kmp_user_lock_p ) ) NULL;

             __kmp_set_user_lock_flags_ =
               ( void ( * )( kmp_user_lock_p, kmp_lock_flags_t ) ) NULL;
        }
        break;

#if KMP_OS_LINUX && (KMP_ARCH_X86 || KMP_ARCH_X86_64 || KMP_ARCH_ARM)

        case lk_futex: {
            __kmp_base_user_lock_size = sizeof( kmp_base_futex_lock_t );
            __kmp_user_lock_size = sizeof( kmp_futex_lock_t );

            __kmp_get_user_lock_owner_ =
              ( kmp_int32 ( * )( kmp_user_lock_p ) )
              ( &__kmp_get_futex_lock_owner );

            if ( __kmp_env_consistency_check ) {
                KMP_BIND_USER_LOCK_WITH_CHECKS(futex);
                KMP_BIND_NESTED_USER_LOCK_WITH_CHECKS(futex);
            }
            else {
                KMP_BIND_USER_LOCK(futex);
                KMP_BIND_NESTED_USER_LOCK(futex);
            }

            __kmp_destroy_user_lock_ =
              ( void ( * )( kmp_user_lock_p ) )
              ( &__kmp_destroy_futex_lock );

             __kmp_is_user_lock_initialized_ =
               ( int ( * )( kmp_user_lock_p ) ) NULL;

             __kmp_get_user_lock_location_ =
               ( const ident_t * ( * )( kmp_user_lock_p ) ) NULL;

             __kmp_set_user_lock_location_ =
               ( void ( * )( kmp_user_lock_p, const ident_t * ) ) NULL;

             __kmp_get_user_lock_flags_ =
               ( kmp_lock_flags_t ( * )( kmp_user_lock_p ) ) NULL;

             __kmp_set_user_lock_flags_ =
               ( void ( * )( kmp_user_lock_p, kmp_lock_flags_t ) ) NULL;
        }
        break;

#endif // KMP_OS_LINUX && (KMP_ARCH_X86 || KMP_ARCH_X86_64 || KMP_ARCH_ARM)

        case lk_ticket: {
            __kmp_base_user_lock_size = sizeof( kmp_base_ticket_lock_t );
            __kmp_user_lock_size = sizeof( kmp_ticket_lock_t );

            __kmp_get_user_lock_owner_ =
              ( kmp_int32 ( * )( kmp_user_lock_p ) )
              ( &__kmp_get_ticket_lock_owner );

            if ( __kmp_env_consistency_check ) {
                KMP_BIND_USER_LOCK_WITH_CHECKS(ticket);
                KMP_BIND_NESTED_USER_LOCK_WITH_CHECKS(ticket);
            }
            else {
                KMP_BIND_USER_LOCK(ticket);
                KMP_BIND_NESTED_USER_LOCK(ticket);
            }

            __kmp_destroy_user_lock_ =
              ( void ( * )( kmp_user_lock_p ) )
              ( &__kmp_destroy_ticket_lock );

             __kmp_is_user_lock_initialized_ =
               ( int ( * )( kmp_user_lock_p ) )
               ( &__kmp_is_ticket_lock_initialized );

             __kmp_get_user_lock_location_ =
               ( const ident_t * ( * )( kmp_user_lock_p ) )
               ( &__kmp_get_ticket_lock_location );

             __kmp_set_user_lock_location_ =
               ( void ( * )( kmp_user_lock_p, const ident_t * ) )
               ( &__kmp_set_ticket_lock_location );

             __kmp_get_user_lock_flags_ =
               ( kmp_lock_flags_t ( * )( kmp_user_lock_p ) )
               ( &__kmp_get_ticket_lock_flags );

             __kmp_set_user_lock_flags_ =
               ( void ( * )( kmp_user_lock_p, kmp_lock_flags_t ) )
               ( &__kmp_set_ticket_lock_flags );
        }
        break;

        case lk_queuing: {
            __kmp_base_user_lock_size = sizeof( kmp_base_queuing_lock_t );
            __kmp_user_lock_size = sizeof( kmp_queuing_lock_t );

            __kmp_get_user_lock_owner_ =
              ( kmp_int32 ( * )( kmp_user_lock_p ) )
              ( &__kmp_get_queuing_lock_owner );

            if ( __kmp_env_consistency_check ) {
                KMP_BIND_USER_LOCK_WITH_CHECKS(queuing);
                KMP_BIND_NESTED_USER_LOCK_WITH_CHECKS(queuing);
            }
            else {
                KMP_BIND_USER_LOCK(queuing);
                KMP_BIND_NESTED_USER_LOCK(queuing);
            }

            __kmp_destroy_user_lock_ =
              ( void ( * )( kmp_user_lock_p ) )
              ( &__kmp_destroy_queuing_lock );

             __kmp_is_user_lock_initialized_ =
               ( int ( * )( kmp_user_lock_p ) )
               ( &__kmp_is_queuing_lock_initialized );

             __kmp_get_user_lock_location_ =
               ( const ident_t * ( * )( kmp_user_lock_p ) )
               ( &__kmp_get_queuing_lock_location );

             __kmp_set_user_lock_location_ =
               ( void ( * )( kmp_user_lock_p, const ident_t * ) )
               ( &__kmp_set_queuing_lock_location );

             __kmp_get_user_lock_flags_ =
               ( kmp_lock_flags_t ( * )( kmp_user_lock_p ) )
               ( &__kmp_get_queuing_lock_flags );

             __kmp_set_user_lock_flags_ =
               ( void ( * )( kmp_user_lock_p, kmp_lock_flags_t ) )
               ( &__kmp_set_queuing_lock_flags );
        }
        break;

#if KMP_USE_ADAPTIVE_LOCKS
        case lk_adaptive: {
            __kmp_base_user_lock_size = sizeof( kmp_base_adaptive_lock_t );
            __kmp_user_lock_size = sizeof( kmp_adaptive_lock_t );

            __kmp_get_user_lock_owner_ =
              ( kmp_int32 ( * )( kmp_user_lock_p ) )
              ( &__kmp_get_queuing_lock_owner );

            if ( __kmp_env_consistency_check ) {
                KMP_BIND_USER_LOCK_WITH_CHECKS(adaptive);
            }
            else {
                KMP_BIND_USER_LOCK(adaptive);
            }

            __kmp_destroy_user_lock_ =
              ( void ( * )( kmp_user_lock_p ) )
              ( &__kmp_destroy_adaptive_lock );

            __kmp_is_user_lock_initialized_ =
              ( int ( * )( kmp_user_lock_p ) )
              ( &__kmp_is_queuing_lock_initialized );

            __kmp_get_user_lock_location_ =
              ( const ident_t * ( * )( kmp_user_lock_p ) )
              ( &__kmp_get_queuing_lock_location );

            __kmp_set_user_lock_location_ =
              ( void ( * )( kmp_user_lock_p, const ident_t * ) )
              ( &__kmp_set_queuing_lock_location );

            __kmp_get_user_lock_flags_ =
              ( kmp_lock_flags_t ( * )( kmp_user_lock_p ) )
              ( &__kmp_get_queuing_lock_flags );

            __kmp_set_user_lock_flags_ =
              ( void ( * )( kmp_user_lock_p, kmp_lock_flags_t ) )
              ( &__kmp_set_queuing_lock_flags );

        }
        break;
#endif // KMP_USE_ADAPTIVE_LOCKS

        case lk_drdpa: {
            __kmp_base_user_lock_size = sizeof( kmp_base_drdpa_lock_t );
            __kmp_user_lock_size = sizeof( kmp_drdpa_lock_t );

            __kmp_get_user_lock_owner_ =
              ( kmp_int32 ( * )( kmp_user_lock_p ) )
              ( &__kmp_get_drdpa_lock_owner );

            if ( __kmp_env_consistency_check ) {
                KMP_BIND_USER_LOCK_WITH_CHECKS(drdpa);
                KMP_BIND_NESTED_USER_LOCK_WITH_CHECKS(drdpa);
            }
            else {
                KMP_BIND_USER_LOCK(drdpa);
                KMP_BIND_NESTED_USER_LOCK(drdpa);
            }

            __kmp_destroy_user_lock_ =
              ( void ( * )( kmp_user_lock_p ) )
              ( &__kmp_destroy_drdpa_lock );

             __kmp_is_user_lock_initialized_ =
               ( int ( * )( kmp_user_lock_p ) )
               ( &__kmp_is_drdpa_lock_initialized );

             __kmp_get_user_lock_location_ =
               ( const ident_t * ( * )( kmp_user_lock_p ) )
               ( &__kmp_get_drdpa_lock_location );

             __kmp_set_user_lock_location_ =
               ( void ( * )( kmp_user_lock_p, const ident_t * ) )
               ( &__kmp_set_drdpa_lock_location );

             __kmp_get_user_lock_flags_ =
               ( kmp_lock_flags_t ( * )( kmp_user_lock_p ) )
               ( &__kmp_get_drdpa_lock_flags );

             __kmp_set_user_lock_flags_ =
               ( void ( * )( kmp_user_lock_p, kmp_lock_flags_t ) )
               ( &__kmp_set_drdpa_lock_flags );
        }
        break;
    }
}


// ----------------------------------------------------------------------------
// User lock table & lock allocation

kmp_lock_table_t __kmp_user_lock_table = { 1, 0, NULL };
kmp_user_lock_p __kmp_lock_pool = NULL;

// Lock block-allocation support.
kmp_block_of_locks* __kmp_lock_blocks = NULL;
int __kmp_num_locks_in_block = 1;             // FIXME - tune this value

static kmp_lock_index_t
__kmp_lock_table_insert( kmp_user_lock_p lck )
{
    // Assume that kmp_global_lock is held upon entry/exit.
    kmp_lock_index_t index;
    if ( __kmp_user_lock_table.used >= __kmp_user_lock_table.allocated ) {
        kmp_lock_index_t size;
        kmp_user_lock_p *table;
        kmp_lock_index_t i;
        // Reallocate lock table.
        if ( __kmp_user_lock_table.allocated == 0 ) {
            size = 1024;
        }
        else {
            size = __kmp_user_lock_table.allocated * 2;
        }
        table = (kmp_user_lock_p *)__kmp_allocate( sizeof( kmp_user_lock_p ) * size );
        memcpy( table + 1, __kmp_user_lock_table.table + 1, sizeof( kmp_user_lock_p ) * ( __kmp_user_lock_table.used - 1 ) );
        table[ 0 ] = (kmp_user_lock_p)__kmp_user_lock_table.table;
            // We cannot free the previos table now, sinse it may be in use by other
            // threads. So save the pointer to the previous table in in the first element of the
            // new table. All the tables will be organized into a list, and could be freed when
            // library shutting down.
        __kmp_user_lock_table.table = table;
        __kmp_user_lock_table.allocated = size;
    }
    KMP_DEBUG_ASSERT( __kmp_user_lock_table.used < __kmp_user_lock_table.allocated );
    index = __kmp_user_lock_table.used;
    __kmp_user_lock_table.table[ index ] = lck;
    ++ __kmp_user_lock_table.used;
    return index;
}

static kmp_user_lock_p
__kmp_lock_block_allocate()
{
    // Assume that kmp_global_lock is held upon entry/exit.
    static int last_index = 0;
    if ( ( last_index >= __kmp_num_locks_in_block )
      || ( __kmp_lock_blocks == NULL ) ) {
        // Restart the index.
        last_index = 0;
        // Need to allocate a new block.
        KMP_DEBUG_ASSERT( __kmp_user_lock_size > 0 );
        size_t space_for_locks = __kmp_user_lock_size * __kmp_num_locks_in_block;
        char* buffer = (char*)__kmp_allocate( space_for_locks + sizeof( kmp_block_of_locks ) );
        // Set up the new block.
        kmp_block_of_locks *new_block = (kmp_block_of_locks *)(& buffer[space_for_locks]);
        new_block->next_block = __kmp_lock_blocks;
        new_block->locks = (void *)buffer;
        // Publish the new block.
        KMP_MB();
        __kmp_lock_blocks = new_block;
    }
    kmp_user_lock_p ret = (kmp_user_lock_p)(& ( ( (char *)( __kmp_lock_blocks->locks ) )
      [ last_index * __kmp_user_lock_size ] ) );
    last_index++;
    return ret;
}

//
// Get memory for a lock. It may be freshly allocated memory or reused memory
// from lock pool.
//
kmp_user_lock_p
__kmp_user_lock_allocate( void **user_lock, kmp_int32 gtid,
  kmp_lock_flags_t flags )
{
    kmp_user_lock_p lck;
    kmp_lock_index_t index;
    KMP_DEBUG_ASSERT( user_lock );

    __kmp_acquire_lock( &__kmp_global_lock, gtid );

    if ( __kmp_lock_pool == NULL ) {
        // Lock pool is empty. Allocate new memory.
        if ( __kmp_num_locks_in_block <= 1 ) { // Tune this cutoff point.
            lck = (kmp_user_lock_p) __kmp_allocate( __kmp_user_lock_size );
        }
        else {
            lck = __kmp_lock_block_allocate();
        }

        // Insert lock in the table so that it can be freed in __kmp_cleanup,
        // and debugger has info on all allocated locks.
        index = __kmp_lock_table_insert( lck );
    }
    else {
        // Pick up lock from pool.
        lck = __kmp_lock_pool;
        index = __kmp_lock_pool->pool.index;
        __kmp_lock_pool = __kmp_lock_pool->pool.next;
    }

    //
    // We could potentially differentiate between nested and regular locks
    // here, and do the lock table lookup for regular locks only.
    //
    if ( OMP_LOCK_T_SIZE < sizeof(void *) ) {
        * ( (kmp_lock_index_t *) user_lock ) = index;
    }
    else {
        * ( (kmp_user_lock_p *) user_lock ) = lck;
    }

    // mark the lock if it is critical section lock.
    __kmp_set_user_lock_flags( lck, flags );

    __kmp_release_lock( & __kmp_global_lock, gtid ); // AC: TODO: move this line upper

    return lck;
}

// Put lock's memory to pool for reusing.
void
__kmp_user_lock_free( void **user_lock, kmp_int32 gtid, kmp_user_lock_p lck )
{
    kmp_lock_pool_t * lock_pool;

    KMP_DEBUG_ASSERT( user_lock != NULL );
    KMP_DEBUG_ASSERT( lck != NULL );

    __kmp_acquire_lock( & __kmp_global_lock, gtid );

    lck->pool.next = __kmp_lock_pool;
    __kmp_lock_pool = lck;
    if ( OMP_LOCK_T_SIZE < sizeof(void *) ) {
        kmp_lock_index_t index = * ( (kmp_lock_index_t *) user_lock );
        KMP_DEBUG_ASSERT( 0 < index && index <= __kmp_user_lock_table.used );
        lck->pool.index = index;
    }

    __kmp_release_lock( & __kmp_global_lock, gtid );
}

kmp_user_lock_p
__kmp_lookup_user_lock( void **user_lock, char const *func )
{
    kmp_user_lock_p lck = NULL;

    if ( __kmp_env_consistency_check ) {
        if ( user_lock == NULL ) {
            KMP_FATAL( LockIsUninitialized, func );
        }
    }

    if ( OMP_LOCK_T_SIZE < sizeof(void *) ) {
        kmp_lock_index_t index = *( (kmp_lock_index_t *)user_lock );
        if ( __kmp_env_consistency_check ) {
            if ( ! ( 0 < index && index < __kmp_user_lock_table.used ) ) {
                KMP_FATAL( LockIsUninitialized, func );
            }
        }
        KMP_DEBUG_ASSERT( 0 < index && index < __kmp_user_lock_table.used );
        KMP_DEBUG_ASSERT( __kmp_user_lock_size > 0 );
        lck = __kmp_user_lock_table.table[index];
    }
    else {
        lck = *( (kmp_user_lock_p *)user_lock );
    }

    if ( __kmp_env_consistency_check ) {
        if ( lck == NULL ) {
            KMP_FATAL( LockIsUninitialized, func );
        }
    }

    return lck;
}

void
__kmp_cleanup_user_locks( void )
{
    //
    // Reset lock pool. Do not worry about lock in the pool -- we will free
    // them when iterating through lock table (it includes all the locks,
    // dead or alive).
    //
    __kmp_lock_pool = NULL;

#define IS_CRITICAL(lck) \
        ( ( __kmp_get_user_lock_flags_ != NULL ) && \
        ( ( *__kmp_get_user_lock_flags_ )( lck ) & kmp_lf_critical_section ) )

    //
    // Loop through lock table, free all locks.
    //
    // Do not free item [0], it is reserved for lock tables list.
    //
    // FIXME - we are iterating through a list of (pointers to) objects of
    // type union kmp_user_lock, but we have no way of knowing whether the
    // base type is currently "pool" or whatever the global user lock type
    // is.
    //
    // We are relying on the fact that for all of the user lock types
    // (except "tas"), the first field in the lock struct is the "initialized"
    // field, which is set to the address of the lock object itself when
    // the lock is initialized.  When the union is of type "pool", the
    // first field is a pointer to the next object in the free list, which
    // will not be the same address as the object itself.
    //
    // This means that the check ( *__kmp_is_user_lock_initialized_ )( lck )
    // will fail for "pool" objects on the free list.  This must happen as
    // the "location" field of real user locks overlaps the "index" field
    // of "pool" objects.
    //
    // It would be better to run through the free list, and remove all "pool"
    // objects from the lock table before executing this loop.  However,
    // "pool" objects do not always have their index field set (only on
    // lin_32e), and I don't want to search the lock table for the address
    // of every "pool" object on the free list.
    //
    while ( __kmp_user_lock_table.used > 1 ) {
        const ident *loc;

        //
        // reduce __kmp_user_lock_table.used before freeing the lock,
        // so that state of locks is consistent
        //
        kmp_user_lock_p lck = __kmp_user_lock_table.table[
          --__kmp_user_lock_table.used ];

        if ( ( __kmp_is_user_lock_initialized_ != NULL ) &&
          ( *__kmp_is_user_lock_initialized_ )( lck ) ) {
            //
            // Issue a warning if: KMP_CONSISTENCY_CHECK AND lock is
            // initialized AND it is NOT a critical section (user is not
            // responsible for destroying criticals) AND we know source
            // location to report.
            //
            if ( __kmp_env_consistency_check && ( ! IS_CRITICAL( lck ) ) &&
              ( ( loc = __kmp_get_user_lock_location( lck ) ) != NULL ) &&
              ( loc->psource != NULL ) ) {
                kmp_str_loc_t str_loc = __kmp_str_loc_init( loc->psource, 0 );
                KMP_WARNING( CnsLockNotDestroyed, str_loc.file, str_loc.func,
                  str_loc.line, str_loc.col );
                __kmp_str_loc_free( &str_loc);
            }

#ifdef KMP_DEBUG
            if ( IS_CRITICAL( lck ) ) {
                KA_TRACE( 20, ("__kmp_cleanup_user_locks: free critical section lock %p (%p)\n", lck, *(void**)lck ) );
            }
            else {
                KA_TRACE( 20, ("__kmp_cleanup_user_locks: free lock %p (%p)\n", lck, *(void**)lck ) );
            }
#endif // KMP_DEBUG

            //
            // Cleanup internal lock dynamic resources
            // (for drdpa locks particularly).
            //
            __kmp_destroy_user_lock( lck );
        }

        //
        // Free the lock if block allocation of locks is not used.
        //
        if ( __kmp_lock_blocks == NULL ) {
            __kmp_free( lck );
        }
    }

#undef IS_CRITICAL

    //
    // delete lock table(s).
    //
    kmp_user_lock_p *table_ptr = __kmp_user_lock_table.table;
    __kmp_user_lock_table.table = NULL;
    __kmp_user_lock_table.allocated = 0;

    while ( table_ptr != NULL ) {
        //
        // In the first element we saved the pointer to the previous
        // (smaller) lock table.
        //
        kmp_user_lock_p *next = (kmp_user_lock_p *)( table_ptr[ 0 ] );
        __kmp_free( table_ptr );
        table_ptr = next;
    }

    //
    // Free buffers allocated for blocks of locks.
    //
    kmp_block_of_locks_t *block_ptr = __kmp_lock_blocks;
    __kmp_lock_blocks = NULL;

    while ( block_ptr != NULL ) {
        kmp_block_of_locks_t *next = block_ptr->next_block;
        __kmp_free( block_ptr->locks );
        //
        // *block_ptr itself was allocated at the end of the locks vector.
        //
	block_ptr = next;
    }

    TCW_4(__kmp_init_user_locks, FALSE);
}