Add support for Intel's umonitor/umwait

[tlwilmar]

Summary

These changes add support for Intel's umonitor/umwait usage in wait code, for architectures that support those intrinsic functions. Usage of umonitor/umwait is off by default, but can be turned on by setting the KMP_USER_LEVEL_MWAIT environment variable.

Patch by Terry Wilmarth and Johnny Peyton.

[AndreyChurbanov]

LGTM

[mstorsjo]

This broke compilation for me:

../runtime/src/kmp.h:1371:3: error: always_inline function '_umonitor' requires target feature 'waitpkg', but would be inlined into function '__kmp_umonitor' that is compiled without support for 'waitpkg'
  _umonitor(cacheline);
  ^ 
../runtime/src/kmp.h:1390:10: error: always_inline function '_umwait' requires target feature 'waitpkg', but would be inlined into function '__kmp_umwait' that is compiled without support for 'waitpkg'
  return _umwait(hint, counter);
         ^
2 errors generated.

[AndreyChurbanov]

In D91189#2407339, @mstorsjo wrote:

This broke compilation for me:

../runtime/src/kmp.h:1371:3: error: always_inline function '_umonitor' requires target feature 'waitpkg', but would be inlined into function '__kmp_umonitor' that is compiled without support for 'waitpkg'
  _umonitor(cacheline);
  ^ 
../runtime/src/kmp.h:1390:10: error: always_inline function '_umwait' requires target feature 'waitpkg', but would be inlined into function '__kmp_umwait' that is compiled without support for 'waitpkg'
  return _umwait(hint, counter);
         ^
2 errors generated.

I reverted the commit until we fix it.

[jlpeyton]

In D91189#2407339, @mstorsjo wrote:

This broke compilation for me:

Which compiler/version are you using?

[mstorsjo]

In D91189#2408728, @jlpeyton wrote:

In D91189#2407339, @mstorsjo wrote:

This broke compilation for me:

Which compiler/version are you using?

Latest nightly clang, targeting mingw.

[MaskRay]

In D91189#2403822, @AndreyChurbanov wrote:

LGTM

https://llvm.org/docs/DeveloperPolicy.html#commit-messages Please use git commit --amend --author= for future patches for proper attribution.

[AndreyChurbanov]

In D91189#2415139, @MaskRay wrote:

https://llvm.org/docs/DeveloperPolicy.html#commit-messages Please use git commit --amend --author= for future patches for proper attribution.

Will do. Thanks for the notice.

[tlwilmar]

Fixed build problems associated with target attribute for waitpkg.

[tlwilmar]

Build problems associated with target attribute for waitpkg should be fixed now. Please try the new diff.

[mstorsjo]

In D91189#2424670, @tlwilmar wrote:

Build problems associated with target attribute for waitpkg should be fixed now. Please try the new diff.

Thanks, now it does seem to build correctly in my configurations.

[jlpeyton]

Sorry, I missed one thing.

openmp/runtime/src/kmp_lock.cpp

2779–2781 ↗

(On Diff #308534)

Change these three lines to just KMP_ATTRIBUTE_TARGET_RTM

[tlwilmar]

One missed change added.

[jlpeyton]

LGTM now.

openmp/runtime/src/i18n/en_US.txt

 AffGranTopGroup              "%1$s: granularity=%2$s is not supported with KMP_TOPOLOGY_METHOD=group. Using \"granularity=fine\"."
 AffGranGroupType             "%1$s: granularity=group is not supported with KMP_AFFINITY=%2$s. Using \"granularity=core\"."
 AffHWSubsetManySockets       "KMP_HW_SUBSET ignored: too many sockets requested."
 AffHWSubsetDeprecated        "KMP_HW_SUBSET \"o\" offset designator deprecated, please use @ prefix for offset value."
 AffUsingHwloc                "%1$s: Affinity capable, using hwloc."
 AffIgnoringHwloc             "%1$s: Ignoring hwloc mechanism."
 AffHwlocErrorOccurred        "%1$s: Hwloc failed in %2$s. Relying on internal affinity mechanisms."
 EnvSerialWarn                "%1$s must be set prior to OpenMP runtime library initialization; ignored."
+EnvMwaitWarn                 "You have enabled the use of umonitor/umwait. If the CPU doesn't have that enabled "
+                             "you'll get an illegal instruction exception."
 EnvVarDeprecated             "%1$s variable deprecated, please use %2$s instead."
 RedMethodNotSupported        "KMP_FORCE_REDUCTION: %1$s method is not supported; using critical."
 AffHWSubsetNoHWLOC           "KMP_HW_SUBSET ignored: unsupported item requested for non-HWLOC topology method (KMP_TOPOLOGY_METHOD)"
 AffHWSubsetManyNodes         "KMP_HW_SUBSET ignored: too many NUMA Nodes requested."
 AffHWSubsetManyTiles         "KMP_HW_SUBSET ignored: too many L2 Caches requested."
 AffHWSubsetManyProcs         "KMP_HW_SUBSET ignored: too many Procs requested."
 HierSchedInvalid             "Hierarchy ignored: unsupported level: %1$s."
 AffFormatDefault             "OMP: pid %1$s tid %2$s thread %3$s bound to OS proc set {%4$s}"

openmp/runtime/src/kmp.h

 // Some forward declarations.
 typedef union kmp_team kmp_team_t;
 typedef struct kmp_taskdata kmp_taskdata_t;
 typedef union kmp_task_team kmp_task_team_t;
 typedef union kmp_team kmp_team_p;
 typedef union kmp_info kmp_info_p;
 typedef union kmp_root kmp_root_p;
 
+template <bool C = false, bool S = true> class kmp_flag_32;
+template <bool C = false, bool S = true> class kmp_flag_64;
+class kmp_flag_oncore;
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 /* ------------------------------------------------------------------------ */
 
 /* Pack two 32-bit signed integers into a 64-bit signed integer */
 /* ToDo: Fix word ordering for big-endian machines. */
else if (__kmp_use_yield == 1) {                                           \
       (count) -= 2;                                                            \
       if (!(count)) {                                                          \
         __kmp_yield();                                                         \
         (count) = __kmp_yield_next;                                            \
       }                                                                        \
     }                                                                          \
   }
 
+// User-level Monitor/Mwait
+#if KMP_HAVE_UMWAIT
+// We always try for UMWAIT first
+#if (KMP_COMPILER_ICC && __INTEL_COMPILER >= 1300) ||                          \
+    (KMP_COMPILER_MSVC && _MSC_VER >= 1700) ||                                 \
+    (KMP_COMPILER_CLANG && (KMP_MSVC_COMPAT || __MINGW32__)) ||                \
+    (KMP_COMPILER_GCC && __MINGW32__)
+#if KMP_OS_UNIX
+#include <immintrin.h>
+#else
+#include <intrin.h>
+#endif // KMP_OS_UNIX
+#else
+#define USE_MWAIT_ASM                                                          \
+  KMP_OS_UNIX && (!KMP_COMPILER_ICC || __INTEL_COMPILER < 1900)
+#endif // KMP_COMPILER_ICC etc.
+#if KMP_OS_UNIX && 0 // "waitpkg" not recognized yet
+__attribute__((target("waitpkg")))
+#endif
+static inline int
+__kmp_tpause(uint32_t hint, uint64_t counter) {
+#if (USE_MWAIT_ASM)
+  uint32_t timeHi = uint32_t(counter >> 32);
+  uint32_t timeLo = uint32_t(counter & 0xffffffff);
+  char flag;
+  __asm__ volatile("#tpause\n.byte 0x66, 0x0F, 0xAE, 0xF1\n"
+                   "setb   %0"
+                   : "=r"(flag)
+                   : "a"(timeLo), "d"(timeHi), "c"(hint)
+                   :);
+  return flag;
+#else
+  return _tpause(hint, counter);
+#endif
+}
+#if KMP_OS_UNIX && 0 // "waitpkg" not recognized on our build machine
+__attribute__((target("waitpkg")))
+#endif
+static inline void
+__kmp_umonitor(void *cacheline) {
+#if (USE_MWAIT_ASM)
+  __asm__ volatile("# umonitor\n.byte 0xF3, 0x0F, 0xAE, 0x01 "
+                   :
+                   : "a"(cacheline)
+                   :);
+#else
+  _umonitor(cacheline);
+#endif
+}
+#if KMP_OS_UNIX && 0 // "waitpkg" not recognized on our build machine
+__attribute__((target("waitpkg")))
+#endif
+static inline int
+__kmp_umwait(uint32_t hint, uint64_t counter) {
+#if (USE_MWAIT_ASM)
+  uint32_t timeHi = uint32_t(counter >> 32);
+  uint32_t timeLo = uint32_t(counter & 0xffffffff);
+  char flag;
+  __asm__ volatile("#umwait\n.byte 0xF2, 0x0F, 0xAE, 0xF1\n"
+                   "setb   %0"
+                   : "=r"(flag)
+                   : "a"(timeLo), "d"(timeHi), "c"(hint)
+                   :);
+  return flag;
+#else
+  return _umwait(hint, counter);
+#endif
+}
+#elif KMP_HAVE_MWAIT
+#if KMP_OS_UNIX
+#include <pmmintrin.h>
+#else
+#include <intrin.h>
+#endif
+#if KMP_OS_UNIX
+__attribute__((target("sse3")))
+#endif
+static inline void
+__kmp_mm_monitor(void *cacheline, unsigned extensions, unsigned hints) {
+  _mm_monitor(cacheline, extensions, hints);
+}
+#if KMP_OS_UNIX
+__attribute__((target("sse3")))
+#endif
+static inline void
+__kmp_mm_mwait(unsigned extensions, unsigned hints) {
+  _mm_mwait(extensions, hints);
+}
+#endif // KMP_HAVE_UMWAIT
+
 /* ------------------------------------------------------------------------ */
 /* Support datatypes for the orphaned construct nesting checks.             */
 /* ------------------------------------------------------------------------ */
 
 enum cons_type {
   ct_none,
   ct_parallel,
   ct_pdo,
static inline kmp_team_t *__kmp_team_from_gtid(int gtid) {
   return __kmp_threads[gtid]->th.th_team;
 }
 
 static inline void __kmp_assert_valid_gtid(kmp_int32 gtid) {
   if (UNLIKELY(gtid < 0 || gtid >= __kmp_threads_capacity))
     KMP_FATAL(ThreadIdentInvalid);
 }
 
+#if KMP_HAVE_MWAIT || KMP_HAVE_UMWAIT
+extern int __kmp_user_level_mwait; // TRUE or FALSE; from KMP_USER_LEVEL_MWAIT
+extern int __kmp_umwait_enabled; // Runtime check if user-level mwait enabled
+extern int __kmp_mwait_enabled; // Runtime check if ring3 mwait is enabled
+extern int __kmp_mwait_hints; // Hints to pass in to mwait
+#endif
+
 /* ------------------------------------------------------------------------- */
 
 extern kmp_global_t __kmp_global; /* global status */
 
 extern kmp_info_t __kmp_monitor;
 // For Debugging Support Library
 extern std::atomic<kmp_int32> __kmp_team_counter;
 // For Debugging Support Library

 extern kmp_uint32 __kmp_ge_4(kmp_uint32 value, kmp_uint32 checker);
 extern kmp_uint32 __kmp_le_4(kmp_uint32 value, kmp_uint32 checker);
 extern kmp_uint32 __kmp_wait_4(kmp_uint32 volatile *spinner, kmp_uint32 checker,
                                kmp_uint32 (*pred)(kmp_uint32, kmp_uint32),
                                void *obj);
 extern void __kmp_wait_4_ptr(void *spinner, kmp_uint32 checker,
                              kmp_uint32 (*pred)(void *, kmp_uint32), void *obj);
 
-class kmp_flag_32;
-class kmp_flag_64;
-class kmp_flag_oncore;
-extern void __kmp_wait_64(kmp_info_t *this_thr, kmp_flag_64 *flag,
+extern void __kmp_wait_64(kmp_info_t *this_thr, kmp_flag_64<> *flag,
                           int final_spin
 #if USE_ITT_BUILD
                           ,
                           void *itt_sync_obj
 #endif
                           );
-extern void __kmp_release_64(kmp_flag_64 *flag);
+extern void __kmp_release_64(kmp_flag_64<> *flag);
 
 extern void __kmp_infinite_loop(void);
 
 extern void __kmp_cleanup(void);
 
 #if KMP_HANDLE_SIGNALS
 extern int __kmp_handle_signals;
 extern void __kmp_install_signals(int parallel_init);

 #endif
 extern void __kmp_reap_worker(kmp_info_t *th);
 extern void __kmp_terminate_thread(int gtid);
 
 extern int __kmp_try_suspend_mx(kmp_info_t *th);
 extern void __kmp_lock_suspend_mx(kmp_info_t *th);
 extern void __kmp_unlock_suspend_mx(kmp_info_t *th);
 
-extern void __kmp_suspend_32(int th_gtid, kmp_flag_32 *flag);
-extern void __kmp_suspend_64(int th_gtid, kmp_flag_64 *flag);
-extern void __kmp_suspend_oncore(int th_gtid, kmp_flag_oncore *flag);
-extern void __kmp_resume_32(int target_gtid, kmp_flag_32 *flag);
-extern void __kmp_resume_64(int target_gtid, kmp_flag_64 *flag);
-extern void __kmp_resume_oncore(int target_gtid, kmp_flag_oncore *flag);
-
 extern void __kmp_elapsed(double *);
 extern void __kmp_elapsed_tick(double *);
 
 extern void __kmp_enable(int old_state);
 extern void __kmp_disable(int *old_state);
 
 extern void __kmp_thread_sleep(int millis);
 

 extern void __kmp_finish_implicit_task(kmp_info_t *this_thr);
 extern void __kmp_free_implicit_task(kmp_info_t *this_thr);
 
 extern kmp_event_t *__kmpc_task_allow_completion_event(ident_t *loc_ref,
                                                        int gtid,
                                                        kmp_task_t *task);
 extern void __kmp_fulfill_event(kmp_event_t *event);
 
-int __kmp_execute_tasks_32(kmp_info_t *thread, kmp_int32 gtid,
-                           kmp_flag_32 *flag, int final_spin,
-                           int *thread_finished,
-#if USE_ITT_BUILD
-                           void *itt_sync_obj,
-#endif /* USE_ITT_BUILD */
-                           kmp_int32 is_constrained);
-int __kmp_execute_tasks_64(kmp_info_t *thread, kmp_int32 gtid,
-                           kmp_flag_64 *flag, int final_spin,
-                           int *thread_finished,
-#if USE_ITT_BUILD
-                           void *itt_sync_obj,
-#endif /* USE_ITT_BUILD */
-                           kmp_int32 is_constrained);
-int __kmp_execute_tasks_oncore(kmp_info_t *thread, kmp_int32 gtid,
-                               kmp_flag_oncore *flag, int final_spin,
-                               int *thread_finished,
-#if USE_ITT_BUILD
-                               void *itt_sync_obj,
-#endif /* USE_ITT_BUILD */
-                               kmp_int32 is_constrained);
-
 extern void __kmp_free_task_team(kmp_info_t *thread,
                                  kmp_task_team_t *task_team);
 extern void __kmp_reap_task_teams(void);
 extern void __kmp_wait_to_unref_task_teams(void);
 extern void __kmp_task_team_setup(kmp_info_t *this_thr, kmp_team_t *team,
                                   int always);
 extern void __kmp_task_team_sync(kmp_info_t *this_thr, kmp_team_t *team);
 extern void __kmp_task_team_wait(kmp_info_t *this_thr, kmp_team_t *team

 }
 
 extern void __kmp_omp_display_env(int verbose);
 
 #ifdef __cplusplus
 }
 #endif
 
+template <bool C, bool S>
+extern void __kmp_suspend_32(int th_gtid, kmp_flag_32<C, S> *flag);
+template <bool C, bool S>
+extern void __kmp_suspend_64(int th_gtid, kmp_flag_64<C, S> *flag);
+extern void __kmp_suspend_oncore(int th_gtid, kmp_flag_oncore *flag);
+template <bool C, bool S>
+#if KMP_HAVE_MWAIT || KMP_HAVE_UMWAIT
+extern void __kmp_mwait_32(int th_gtid, kmp_flag_32<C, S> *flag);
+template <bool C, bool S>
+extern void __kmp_mwait_64(int th_gtid, kmp_flag_64<C, S> *flag);
+extern void __kmp_mwait_oncore(int th_gtid, kmp_flag_oncore *flag);
+template <bool C, bool S>
+#endif
+extern void __kmp_resume_32(int target_gtid, kmp_flag_32<C, S> *flag);
+template <bool C, bool S>
+extern void __kmp_resume_64(int target_gtid, kmp_flag_64<C, S> *flag);
+extern void __kmp_resume_oncore(int target_gtid, kmp_flag_oncore *flag);
+
+template <bool C, bool S>
+int __kmp_execute_tasks_32(kmp_info_t *thread, kmp_int32 gtid,
+                           kmp_flag_32<C, S> *flag, int final_spin,
+                           int *thread_finished,
+#if USE_ITT_BUILD
+                           void *itt_sync_obj,
+#endif /* USE_ITT_BUILD */
+                           kmp_int32 is_constrained);
+template <bool C, bool S>
+int __kmp_execute_tasks_64(kmp_info_t *thread, kmp_int32 gtid,
+                           kmp_flag_64<C, S> *flag, int final_spin,
+                           int *thread_finished,
+#if USE_ITT_BUILD
+                           void *itt_sync_obj,
+#endif /* USE_ITT_BUILD */
+                           kmp_int32 is_constrained);
+int __kmp_execute_tasks_oncore(kmp_info_t *thread, kmp_int32 gtid,
+                               kmp_flag_oncore *flag, int final_spin,
+                               int *thread_finished,
+#if USE_ITT_BUILD
+                               void *itt_sync_obj,
+#endif /* USE_ITT_BUILD */
+                               kmp_int32 is_constrained);
+
 #endif /* KMP_H */

openmp/runtime/src/kmp_barrier.cpp

KA_TRACE(20,
               gtid, team->t.t_id, tid, __kmp_gtid_from_tid(0, team),
               team->t.t_id, 0, &thr_bar->b_arrived, thr_bar->b_arrived,
               thr_bar->b_arrived + KMP_BARRIER_STATE_BUMP));
     // Mark arrival to master thread
     /* After performing this write, a worker thread may not assume that the team
        is valid any more - it could be deallocated by the master thread at any
        time. */
     ANNOTATE_BARRIER_BEGIN(this_thr);
-    kmp_flag_64 flag(&thr_bar->b_arrived, other_threads[0]);
+    kmp_flag_64<> flag(&thr_bar->b_arrived, other_threads[0]);
     flag.release();
   } else {
     kmp_balign_team_t *team_bar = &team->t.t_bar[bt];
     int nproc = this_thr->th.th_team_nproc;
     int i;
     // Don't have to worry about sleep bit here or atomic since team setting
     kmp_uint64 new_state = team_bar->b_arrived + KMP_BARRIER_STATE_BUMP;
 
     // Collect all the worker team member threads.
     for (i = 1; i < nproc; ++i) {
 #if KMP_CACHE_MANAGE
       // Prefetch next thread's arrived count
       if (i + 1 < nproc)
         KMP_CACHE_PREFETCH(&other_threads[i + 1]->th.th_bar[bt].bb.b_arrived);
 #endif /* KMP_CACHE_MANAGE */
       KA_TRACE(20, ("__kmp_linear_barrier_gather: T#%d(%d:%d) wait T#%d(%d:%d) "
                     "arrived(%p) == %llu\n",
                     gtid, team->t.t_id, tid, __kmp_gtid_from_tid(i, team),
                     team->t.t_id, i,
                     &other_threads[i]->th.th_bar[bt].bb.b_arrived, new_state));
 
       // Wait for worker thread to arrive
-      kmp_flag_64 flag(&other_threads[i]->th.th_bar[bt].bb.b_arrived,
-                       new_state);
       if (cancellable) {
-        bool cancelled = flag.wait_cancellable_nosleep(
-            this_thr, FALSE USE_ITT_BUILD_ARG(itt_sync_obj));
-        if (cancelled)
+        kmp_flag_64<true, false> flag(
+            &other_threads[i]->th.th_bar[bt].bb.b_arrived, new_state);
+        if (flag.wait(this_thr, FALSE USE_ITT_BUILD_ARG(itt_sync_obj)))
           return true;
       } else {
+        kmp_flag_64<> flag(&other_threads[i]->th.th_bar[bt].bb.b_arrived,
+                           new_state);
         flag.wait(this_thr, FALSE USE_ITT_BUILD_ARG(itt_sync_obj));
       }
       ANNOTATE_BARRIER_END(other_threads[i]);
 #if USE_ITT_BUILD && USE_ITT_NOTIFY
       // Barrier imbalance - write min of the thread time and the other thread
       // time to the thread.
       if (__kmp_forkjoin_frames_mode == 2) {
         this_thr->th.th_bar_min_time = KMP_MIN(
#endif /* KMP_CACHE_MANAGE */
             20,
             ("__kmp_linear_barrier_release: T#%d(%d:%d) releasing T#%d(%d:%d) "
              "go(%p): %u => %u\n",
              gtid, team->t.t_id, tid, other_threads[i]->th.th_info.ds.ds_gtid,
              team->t.t_id, i, &other_threads[i]->th.th_bar[bt].bb.b_go,
              other_threads[i]->th.th_bar[bt].bb.b_go,
              other_threads[i]->th.th_bar[bt].bb.b_go + KMP_BARRIER_STATE_BUMP));
         ANNOTATE_BARRIER_BEGIN(other_threads[i]);
-        kmp_flag_64 flag(&other_threads[i]->th.th_bar[bt].bb.b_go,
+        kmp_flag_64<> flag(&other_threads[i]->th.th_bar[bt].bb.b_go,
                            other_threads[i]);
         flag.release();
       }
     }
   } else { // Wait for the MASTER thread to release us
     KA_TRACE(20, ("__kmp_linear_barrier_release: T#%d wait go(%p) == %u\n",
                   gtid, &thr_bar->b_go, KMP_BARRIER_STATE_BUMP));
-    kmp_flag_64 flag(&thr_bar->b_go, KMP_BARRIER_STATE_BUMP);
     if (cancellable) {
-      bool cancelled = flag.wait_cancellable_nosleep(
-          this_thr, TRUE USE_ITT_BUILD_ARG(itt_sync_obj));
-      if (cancelled) {
+      kmp_flag_64<true, false> flag(&thr_bar->b_go, KMP_BARRIER_STATE_BUMP);
+      if (flag.wait(this_thr, TRUE USE_ITT_BUILD_ARG(itt_sync_obj)))
         return true;
-      }
     } else {
+      kmp_flag_64<> flag(&thr_bar->b_go, KMP_BARRIER_STATE_BUMP);
       flag.wait(this_thr, TRUE USE_ITT_BUILD_ARG(itt_sync_obj));
     }
     ANNOTATE_BARRIER_END(this_thr);
 #if USE_ITT_BUILD && USE_ITT_NOTIFY
     if ((__itt_sync_create_ptr && itt_sync_obj == NULL) || KMP_ITT_DEBUG) {
       // In a fork barrier; cannot get the object reliably (or ITTNOTIFY is
       // disabled)
       itt_sync_obj = __kmp_itt_barrier_object(gtid, bs_forkjoin_barrier, 0, -1);
#if KMP_CACHE_MANAGE
             &other_threads[child_tid + 1]->th.th_bar[bt].bb.b_arrived);
 #endif /* KMP_CACHE_MANAGE */
       KA_TRACE(20,
                ("__kmp_tree_barrier_gather: T#%d(%d:%d) wait T#%d(%d:%u) "
                 "arrived(%p) == %llu\n",
                 gtid, team->t.t_id, tid, __kmp_gtid_from_tid(child_tid, team),
                 team->t.t_id, child_tid, &child_bar->b_arrived, new_state));
       // Wait for child to arrive
-      kmp_flag_64 flag(&child_bar->b_arrived, new_state);
+      kmp_flag_64<> flag(&child_bar->b_arrived, new_state);
       flag.wait(this_thr, FALSE USE_ITT_BUILD_ARG(itt_sync_obj));
       ANNOTATE_BARRIER_END(child_thr);
 #if USE_ITT_BUILD && USE_ITT_NOTIFY
       // Barrier imbalance - write min of the thread time and a child time to
       // the thread.
       if (__kmp_forkjoin_frames_mode == 2) {
         this_thr->th.th_bar_min_time = KMP_MIN(this_thr->th.th_bar_min_time,
                                                child_thr->th.th_bar_min_time);
KA_TRACE(20,
               team->t.t_id, parent_tid, &thr_bar->b_arrived, thr_bar->b_arrived,
               thr_bar->b_arrived + KMP_BARRIER_STATE_BUMP));
 
     // Mark arrival to parent thread
     /* After performing this write, a worker thread may not assume that the team
        is valid any more - it could be deallocated by the master thread at any
        time.  */
     ANNOTATE_BARRIER_BEGIN(this_thr);
-    kmp_flag_64 flag(&thr_bar->b_arrived, other_threads[parent_tid]);
+    kmp_flag_64<> flag(&thr_bar->b_arrived, other_threads[parent_tid]);
     flag.release();
   } else {
     // Need to update the team arrived pointer if we are the master thread
     if (nproc > 1) // New value was already computed above
       team->t.t_bar[bt].b_arrived = new_state;
     else
       team->t.t_bar[bt].b_arrived += KMP_BARRIER_STATE_BUMP;
     KA_TRACE(20, ("__kmp_tree_barrier_gather: T#%d(%d:%d) set team %d "
static void __kmp_tree_barrier_release(
   kmp_uint32 child_tid;
 
   // Perform a tree release for all of the threads that have been gathered
   if (!KMP_MASTER_TID(
           tid)) { // Handle fork barrier workers who aren't part of a team yet
     KA_TRACE(20, ("__kmp_tree_barrier_release: T#%d wait go(%p) == %u\n", gtid,
                   &thr_bar->b_go, KMP_BARRIER_STATE_BUMP));
     // Wait for parent thread to release us
-    kmp_flag_64 flag(&thr_bar->b_go, KMP_BARRIER_STATE_BUMP);
+    kmp_flag_64<> flag(&thr_bar->b_go, KMP_BARRIER_STATE_BUMP);
     flag.wait(this_thr, TRUE USE_ITT_BUILD_ARG(itt_sync_obj));
     ANNOTATE_BARRIER_END(this_thr);
 #if USE_ITT_BUILD && USE_ITT_NOTIFY
     if ((__itt_sync_create_ptr && itt_sync_obj == NULL) || KMP_ITT_DEBUG) {
       // In fork barrier where we could not get the object reliably (or
       // ITTNOTIFY is disabled)
       itt_sync_obj = __kmp_itt_barrier_object(gtid, bs_forkjoin_barrier, 0, -1);
       // Cancel wait on previous parallel region...
#endif // KMP_BARRIER_ICV_PUSH
       KA_TRACE(20,
                ("__kmp_tree_barrier_release: T#%d(%d:%d) releasing T#%d(%d:%u)"
                 "go(%p): %u => %u\n",
                 gtid, team->t.t_id, tid, __kmp_gtid_from_tid(child_tid, team),
                 team->t.t_id, child_tid, &child_bar->b_go, child_bar->b_go,
                 child_bar->b_go + KMP_BARRIER_STATE_BUMP));
       // Release child from barrier
       ANNOTATE_BARRIER_BEGIN(child_thr);
-      kmp_flag_64 flag(&child_bar->b_go, child_thr);
+      kmp_flag_64<> flag(&child_bar->b_go, child_thr);
       flag.release();
       child++;
       child_tid++;
     } while (child <= branch_factor && child_tid < nproc);
   }
   KA_TRACE(
       20, ("__kmp_tree_barrier_release: T#%d(%d:%d) exit for barrier type %d\n",
            gtid, team->t.t_id, tid, bt));
#if USE_ITT_BUILD && USE_ITT_NOTIFY
   // Barrier imbalance - save arrive time to the thread
   if (__kmp_forkjoin_frames_mode == 3 || __kmp_forkjoin_frames_mode == 2) {
     this_thr->th.th_bar_arrive_time = this_thr->th.th_bar_min_time =
         __itt_get_timestamp();
   }
 #endif
   /* Perform a hypercube-embedded tree gather to wait until all of the threads
      have arrived, and reduce any required data as we go.  */
-  kmp_flag_64 p_flag(&thr_bar->b_arrived);
+  kmp_flag_64<> p_flag(&thr_bar->b_arrived);
   for (level = 0, offset = 1; offset < num_threads;
        level += branch_bits, offset <<= branch_bits) {
     kmp_uint32 child;
     kmp_uint32 child_tid;
 
     if (((tid >> level) & (branch_factor - 1)) != 0) {
       kmp_int32 parent_tid = tid & ~((1 << (level + branch_bits)) - 1);
 
#if KMP_CACHE_MANAGE
             &other_threads[next_child_tid]->th.th_bar[bt].bb.b_arrived);
 #endif /* KMP_CACHE_MANAGE */
       KA_TRACE(20,
                ("__kmp_hyper_barrier_gather: T#%d(%d:%d) wait T#%d(%d:%u) "
                 "arrived(%p) == %llu\n",
                 gtid, team->t.t_id, tid, __kmp_gtid_from_tid(child_tid, team),
                 team->t.t_id, child_tid, &child_bar->b_arrived, new_state));
       // Wait for child to arrive
-      kmp_flag_64 c_flag(&child_bar->b_arrived, new_state);
+      kmp_flag_64<> c_flag(&child_bar->b_arrived, new_state);
       c_flag.wait(this_thr, FALSE USE_ITT_BUILD_ARG(itt_sync_obj));
       ANNOTATE_BARRIER_END(child_thr);
       KMP_MB(); // Synchronize parent and child threads.
 #if USE_ITT_BUILD && USE_ITT_NOTIFY
       // Barrier imbalance - write min of the thread time and a child time to
       // the thread.
       if (__kmp_forkjoin_frames_mode == 2) {
         this_thr->th.th_bar_min_time = KMP_MIN(this_thr->th.th_bar_min_time,
if (propagate_icvs) { // master already has ICVs in final destination; copy
       copy_icvs(&thr_bar->th_fixed_icvs,
                 &team->t.t_implicit_task_taskdata[tid].td_icvs);
     }
 #endif
   } else { // Handle fork barrier workers who aren't part of a team yet
     KA_TRACE(20, ("__kmp_hyper_barrier_release: T#%d wait go(%p) == %u\n", gtid,
                   &thr_bar->b_go, KMP_BARRIER_STATE_BUMP));
     // Wait for parent thread to release us
-    kmp_flag_64 flag(&thr_bar->b_go, KMP_BARRIER_STATE_BUMP);
+    kmp_flag_64<> flag(&thr_bar->b_go, KMP_BARRIER_STATE_BUMP);
     flag.wait(this_thr, TRUE USE_ITT_BUILD_ARG(itt_sync_obj));
     ANNOTATE_BARRIER_END(this_thr);
 #if USE_ITT_BUILD && USE_ITT_NOTIFY
     if ((__itt_sync_create_ptr && itt_sync_obj == NULL) || KMP_ITT_DEBUG) {
       // In fork barrier where we could not get the object reliably
       itt_sync_obj = __kmp_itt_barrier_object(gtid, bs_forkjoin_barrier, 0, -1);
       // Cancel wait on previous parallel region...
       __kmp_itt_task_starting(itt_sync_obj);
#endif // KMP_BARRIER_ICV_PUSH
             20,
             ("__kmp_hyper_barrier_release: T#%d(%d:%d) releasing T#%d(%d:%u)"
              "go(%p): %u => %u\n",
              gtid, team->t.t_id, tid, __kmp_gtid_from_tid(child_tid, team),
              team->t.t_id, child_tid, &child_bar->b_go, child_bar->b_go,
              child_bar->b_go + KMP_BARRIER_STATE_BUMP));
         // Release child from barrier
         ANNOTATE_BARRIER_BEGIN(child_thr);
-        kmp_flag_64 flag(&child_bar->b_go, child_thr);
+        kmp_flag_64<> flag(&child_bar->b_go, child_thr);
         flag.release();
       }
     }
   }
 #if KMP_BARRIER_ICV_PUSH
   if (propagate_icvs &&
       !KMP_MASTER_TID(tid)) { // copy ICVs locally to final dest
     __kmp_init_implicit_task(team->t.t_ident, team->t.t_threads[tid], team, tid,
if (__kmp_dflt_blocktime == KMP_MAX_BLOCKTIME &&
         // First, wait for leaf children to check-in on my b_arrived flag
         kmp_uint64 leaf_state =
             KMP_MASTER_TID(tid)
                 ? thr_bar->b_arrived | thr_bar->leaf_state
                 : team->t.t_bar[bt].b_arrived | thr_bar->leaf_state;
         KA_TRACE(20, ("__kmp_hierarchical_barrier_gather: T#%d(%d:%d) waiting "
                       "for leaf kids\n",
                       gtid, team->t.t_id, tid));
-        kmp_flag_64 flag(&thr_bar->b_arrived, leaf_state);
+        kmp_flag_64<> flag(&thr_bar->b_arrived, leaf_state);
         flag.wait(this_thr, FALSE USE_ITT_BUILD_ARG(itt_sync_obj));
         if (reduce) {
           ANNOTATE_REDUCE_AFTER(reduce);
           OMPT_REDUCTION_DECL(this_thr, gtid);
           OMPT_REDUCTION_BEGIN;
           for (child_tid = tid + 1; child_tid <= tid + thr_bar->leaf_kids;
                ++child_tid) {
             KA_TRACE(100, ("__kmp_hierarchical_barrier_gather: T#%d(%d:%d) += "
if (__kmp_dflt_blocktime == KMP_MAX_BLOCKTIME &&
           kmp_info_t *child_thr = other_threads[child_tid];
           kmp_bstate_t *child_bar = &child_thr->th.th_bar[bt].bb;
           KA_TRACE(20, ("__kmp_hierarchical_barrier_gather: T#%d(%d:%d) wait "
                         "T#%d(%d:%d) "
                         "arrived(%p) == %llu\n",
                         gtid, team->t.t_id, tid,
                         __kmp_gtid_from_tid(child_tid, team), team->t.t_id,
                         child_tid, &child_bar->b_arrived, new_state));
-          kmp_flag_64 flag(&child_bar->b_arrived, new_state);
+          kmp_flag_64<> flag(&child_bar->b_arrived, new_state);
           flag.wait(this_thr, FALSE USE_ITT_BUILD_ARG(itt_sync_obj));
           ANNOTATE_BARRIER_END(child_thr);
           if (reduce) {
             KA_TRACE(100, ("__kmp_hierarchical_barrier_gather: T#%d(%d:%d) += "
                            "T#%d(%d:%d)\n",
                            gtid, team->t.t_id, tid,
                            __kmp_gtid_from_tid(child_tid, team), team->t.t_id,
                            child_tid));
if (__kmp_dflt_blocktime == KMP_MAX_BLOCKTIME &&
           kmp_info_t *child_thr = other_threads[child_tid];
           kmp_bstate_t *child_bar = &child_thr->th.th_bar[bt].bb;
           KA_TRACE(20, ("__kmp_hierarchical_barrier_gather: T#%d(%d:%d) wait "
                         "T#%d(%d:%d) "
                         "arrived(%p) == %llu\n",
                         gtid, team->t.t_id, tid,
                         __kmp_gtid_from_tid(child_tid, team), team->t.t_id,
                         child_tid, &child_bar->b_arrived, new_state));
-          kmp_flag_64 flag(&child_bar->b_arrived, new_state);
+          kmp_flag_64<> flag(&child_bar->b_arrived, new_state);
           flag.wait(this_thr, FALSE USE_ITT_BUILD_ARG(itt_sync_obj));
           ANNOTATE_BARRIER_END(child_thr);
           if (reduce) {
             KA_TRACE(100, ("__kmp_hierarchical_barrier_gather: T#%d(%d:%d) += "
                            "T#%d(%d:%d)\n",
                            gtid, team->t.t_id, tid,
                            __kmp_gtid_from_tid(child_tid, team), team->t.t_id,
                            child_tid));
KA_TRACE(20, ("__kmp_hierarchical_barrier_gather: T#%d(%d:%d) releasing"
                   thr_bar->b_arrived + KMP_BARRIER_STATE_BUMP));
     /* Mark arrival to parent: After performing this write, a worker thread may
        not assume that the team is valid any more - it could be deallocated by
        the master thread at any time. */
     if (thr_bar->my_level || __kmp_dflt_blocktime != KMP_MAX_BLOCKTIME ||
         !thr_bar->use_oncore_barrier) { // Parent is waiting on my b_arrived
       // flag; release it
       ANNOTATE_BARRIER_BEGIN(this_thr);
-      kmp_flag_64 flag(&thr_bar->b_arrived, other_threads[thr_bar->parent_tid]);
+      kmp_flag_64<> flag(&thr_bar->b_arrived,
+                         other_threads[thr_bar->parent_tid]);
       flag.release();
     } else {
       // Leaf does special release on "offset" bits of parent's b_arrived flag
       thr_bar->b_arrived = team->t.t_bar[bt].b_arrived + KMP_BARRIER_STATE_BUMP;
       kmp_flag_oncore flag(&thr_bar->parent_bar->b_arrived, thr_bar->offset);
       flag.set_waiter(other_threads[thr_bar->parent_tid]);
       flag.release();
     }
KA_TRACE(20, ("__kmp_hierarchical_barrier_release: T#%d(%d:%d) master "
                   gtid, team->t.t_id, tid, bt));
   } else { // Worker threads
     // Wait for parent thread to release me
     if (!thr_bar->use_oncore_barrier ||
         __kmp_dflt_blocktime != KMP_MAX_BLOCKTIME || thr_bar->my_level != 0 ||
         thr_bar->team == NULL) {
       // Use traditional method of waiting on my own b_go flag
       thr_bar->wait_flag = KMP_BARRIER_OWN_FLAG;
-      kmp_flag_64 flag(&thr_bar->b_go, KMP_BARRIER_STATE_BUMP);
+      kmp_flag_64<> flag(&thr_bar->b_go, KMP_BARRIER_STATE_BUMP);
       flag.wait(this_thr, TRUE USE_ITT_BUILD_ARG(itt_sync_obj));
       ANNOTATE_BARRIER_END(this_thr);
       TCW_8(thr_bar->b_go,
             KMP_INIT_BARRIER_STATE); // Reset my b_go flag for next time
     } else { // Thread barrier data is initialized, this is a leaf, blocktime is
       // infinite, not nested
       // Wait on my "offset" bits on parent's b_go flag
       thr_bar->wait_flag = KMP_BARRIER_PARENT_FLAG;
if (__kmp_dflt_blocktime == KMP_MAX_BLOCKTIME &&
                 20,
                 ("__kmp_hierarchical_barrier_release: T#%d(%d:%d) releasing"
                  " T#%d(%d:%d) go(%p): %u => %u\n",
                  gtid, team->t.t_id, tid, __kmp_gtid_from_tid(child_tid, team),
                  team->t.t_id, child_tid, &child_bar->b_go, child_bar->b_go,
                  child_bar->b_go + KMP_BARRIER_STATE_BUMP));
             // Release child using child's b_go flag
             ANNOTATE_BARRIER_BEGIN(child_thr);
-            kmp_flag_64 flag(&child_bar->b_go, child_thr);
+            kmp_flag_64<> flag(&child_bar->b_go, child_thr);
             flag.release();
           }
         } else { // Release all children at once with leaf_state bits on my own
           // b_go flag
           thr_bar->b_go |= thr_bar->leaf_state;
         }
       }
     } else { // Blocktime is not infinite; do a simple hierarchical release
if (__kmp_dflt_blocktime == KMP_MAX_BLOCKTIME &&
           KA_TRACE(20, ("__kmp_hierarchical_barrier_release: T#%d(%d:%d) "
                         "releasing T#%d(%d:%d) go(%p): %u => %u\n",
                         gtid, team->t.t_id, tid,
                         __kmp_gtid_from_tid(child_tid, team), team->t.t_id,
                         child_tid, &child_bar->b_go, child_bar->b_go,
                         child_bar->b_go + KMP_BARRIER_STATE_BUMP));
           // Release child using child's b_go flag
           ANNOTATE_BARRIER_BEGIN(child_thr);
-          kmp_flag_64 flag(&child_bar->b_go, child_thr);
+          kmp_flag_64<> flag(&child_bar->b_go, child_thr);
           flag.release();
         }
       }
     }
 #if KMP_BARRIER_ICV_PUSH
     if (propagate_icvs && !KMP_MASTER_TID(tid))
       // non-leaves copy ICVs from fixed ICVs to local dest
       copy_icvs(&team->t.t_implicit_task_taskdata[tid].td_icvs,

openmp/runtime/src/kmp_global.cpp

 #endif
 
 #endif // KMP_USE_ADAPTIVE_LOCKS
 
 int __kmp_display_env = FALSE;
 int __kmp_display_env_verbose = FALSE;
 int __kmp_omp_cancellation = FALSE;
 
+#if KMP_HAVE_MWAIT || KMP_HAVE_UMWAIT
+int __kmp_user_level_mwait = FALSE;
+int __kmp_umwait_enabled = FALSE;
+int __kmp_mwait_enabled = FALSE;
+int __kmp_mwait_hints = 0;
+#endif
+
 /* map OMP 3.0 schedule types with our internal schedule types */
 enum sched_type __kmp_sch_map[kmp_sched_upper - kmp_sched_lower_ext +
                               kmp_sched_upper_std - kmp_sched_lower - 2] = {
     kmp_sch_static_chunked, // ==> kmp_sched_static            = 1
     kmp_sch_dynamic_chunked, // ==> kmp_sched_dynamic           = 2
     kmp_sch_guided_chunked, // ==> kmp_sched_guided            = 3
     kmp_sch_auto, // ==> kmp_sched_auto              = 4
     kmp_sch_trapezoidal // ==> kmp_sched_trapezoidal       = 101

openmp/runtime/src/kmp_os.h

 #endif // __cplusplus
 
 #define KMP_EXPORT extern /* export declaration in guide libraries */
 
 #if __GNUC__ >= 4 && !defined(__MINGW32__)
 #define __forceinline __inline
 #endif
 
+/* Check if the OS/arch can support user-level mwait */
+// All mwait code tests for UMWAIT first, so it should only fall back to ring3
+// MWAIT for KNL.
+#define KMP_HAVE_MWAIT                                                         \
+  ((KMP_ARCH_X86 || KMP_ARCH_X86_64) && (KMP_OS_LINUX || KMP_OS_WINDOWS) &&    \
+   !KMP_MIC2)
+#define KMP_HAVE_UMWAIT                                                        \
+  ((KMP_ARCH_X86 || KMP_ARCH_X86_64) && (KMP_OS_LINUX || KMP_OS_WINDOWS) &&    \
+   !KMP_MIC)
+
 #if KMP_OS_WINDOWS
 #include <windows.h>
 
 static inline int KMP_GET_PAGE_SIZE(void) {
   SYSTEM_INFO si;
   GetSystemInfo(&si);
   return si.dwPageSize;
 }

openmp/runtime/src/kmp_runtime.cpp

#if KMP_OS_WINDOWS
           // On Windows a thread can be killed at any time, check this
           DWORD ecode;
           if (!__kmp_is_thread_alive(th, &ecode)) {
             *state = KMP_SAFE_TO_REAP; // reset the flag for dead thread
             break;
           }
 #endif
           // first check if thread is sleeping
-          kmp_flag_64 fl(&th->th.th_bar[bs_forkjoin_barrier].bb.b_go, th);
+          kmp_flag_64<> fl(&th->th.th_bar[bs_forkjoin_barrier].bb.b_go, th);
           if (fl.is_sleeping())
             fl.resume(__kmp_gtid_from_thread(th));
           KMP_CPU_PAUSE();
         }
       }
 
       // Delete task teams
       int tt_idx;
if (!is_root) {
     if (__kmp_dflt_blocktime != KMP_MAX_BLOCKTIME) {
       /* Assume the threads are at the fork barrier here */
       KA_TRACE(
           20, ("__kmp_reap_thread: releasing T#%d from fork barrier for reap\n",
                gtid));
       /* Need release fence here to prevent seg faults for tree forkjoin barrier
        * (GEH) */
       ANNOTATE_HAPPENS_BEFORE(thread);
-      kmp_flag_64 flag(&thread->th.th_bar[bs_forkjoin_barrier].bb.b_go, thread);
+      kmp_flag_64<> flag(&thread->th.th_bar[bs_forkjoin_barrier].bb.b_go, thread);
       __kmp_release_64(&flag);
     }
 
     // Terminate OS thread.
     __kmp_reap_worker(thread);
 
     // The thread was killed asynchronously.  If it was actively
     // spinning in the thread pool, decrement the global count.
if ((cs_p->eax & 0xff0) == 0xB10) {
     __kmp_mic_type = mic3;
   } else {
     __kmp_mic_type = non_mic;
   }
 }
 
 #endif /* KMP_MIC_SUPPORTED */
 
+#if KMP_HAVE_UMWAIT
+static void __kmp_user_level_mwait_init() {
+  struct kmp_cpuid buf;
+  __kmp_x86_cpuid(7, 0, &buf);
+  __kmp_umwait_enabled = ((buf.ecx >> 5) & 1) && __kmp_user_level_mwait;
+  KF_TRACE(30, ("__kmp_user_level_mwait_init: __kmp_umwait_enabled = %d\n",
+                __kmp_umwait_enabled));
+}
+#elif KMP_HAVE_MWAIT
+#ifndef AT_INTELPHIUSERMWAIT
+// Spurious, non-existent value that should always fail to return anything.
+// Will be replaced with the correct value when we know that.
+#define AT_INTELPHIUSERMWAIT 10000
+#endif
+// getauxval() function is available in RHEL7 and SLES12. If a system with an
+// earlier OS is used to build the RTL, we'll use the following internal
+// function when the entry is not found.
+unsigned long getauxval(unsigned long) KMP_WEAK_ATTRIBUTE_EXTERNAL;
+unsigned long getauxval(unsigned long) { return 0; }
+
+static void __kmp_user_level_mwait_init() {
+  // When getauxval() and correct value of AT_INTELPHIUSERMWAIT are available
+  // use them to find if the user-level mwait is enabled. Otherwise, forcibly
+  // set __kmp_mwait_enabled=TRUE on Intel MIC if the environment variable
+  // KMP_USER_LEVEL_MWAIT was set to TRUE.
+  if (__kmp_mic_type == mic3) {
+    unsigned long res = getauxval(AT_INTELPHIUSERMWAIT);
+    if ((res & 0x1) || __kmp_user_level_mwait) {
+      __kmp_mwait_enabled = TRUE;
+      if (__kmp_user_level_mwait) {
+        KMP_INFORM(EnvMwaitWarn);
+      }
+    } else {
+      __kmp_mwait_enabled = FALSE;
+    }
+  }
+  KF_TRACE(30, ("__kmp_user_level_mwait_init: __kmp_mic_type = %d, "
+                "__kmp_mwait_enabled = %d\n",
+                __kmp_mic_type, __kmp_mwait_enabled));
+}
+#endif /* KMP_HAVE_UMWAIT */
+
 static void __kmp_do_serial_initialize(void) {
   int i, gtid;
   int size;
 
   KA_TRACE(10, ("__kmp_do_serial_initialize: enter\n"));
 
   KMP_DEBUG_ASSERT(sizeof(kmp_int32) == 4);
   KMP_DEBUG_ASSERT(sizeof(kmp_uint32) == 4);
#endif
   // From "KMP_FOREIGN_THREADS_THREADPRIVATE" initialization
   __kmp_foreign_tp = TRUE;
 
   __kmp_global.g.g_dynamic = FALSE;
   __kmp_global.g.g_dynamic_mode = dynamic_default;
 
   __kmp_env_initialize(NULL);
 
+#if KMP_HAVE_MWAIT || KMP_HAVE_UMWAIT
+  __kmp_user_level_mwait_init();
+#endif
 // Print all messages in message catalog for testing purposes.
 #ifdef KMP_DEBUG
   char const *val = __kmp_env_get("KMP_DUMP_CATALOG");
   if (__kmp_str_match_true(val)) {
     kmp_str_buf_t buffer;
     __kmp_str_buf_init(&buffer);
     __kmp_i18n_dump_catalog(&buffer);
     __kmp_printf("%s", buffer.str);

 // Soft resume sets __kmp_pause_status, and wakes up all threads.
 void __kmp_resume_if_soft_paused() {
   if (__kmp_pause_status == kmp_soft_paused) {
     __kmp_pause_status = kmp_not_paused;
 
     for (int gtid = 1; gtid < __kmp_threads_capacity; ++gtid) {
       kmp_info_t *thread = __kmp_threads[gtid];
       if (thread) { // Wake it if sleeping
-        kmp_flag_64 fl(&thread->th.th_bar[bs_forkjoin_barrier].bb.b_go, thread);
+        kmp_flag_64<> fl(&thread->th.th_bar[bs_forkjoin_barrier].bb.b_go,
+                         thread);
         if (fl.is_sleeping())
           fl.resume(gtid);
         else if (__kmp_try_suspend_mx(thread)) { // got suspend lock
           __kmp_unlock_suspend_mx(thread); // unlock it; it won't sleep
         } else { // thread holds the lock and may sleep soon
           do { // until either the thread sleeps, or we can get the lock
             if (fl.is_sleeping()) {
               fl.resume(gtid);

openmp/runtime/src/kmp_settings.cpp

 } // __kmp_stg_parse_task_throttling
 
 
 static void __kmp_stg_print_task_throttling(kmp_str_buf_t *buffer,
                                             char const *name, void *data) {
   __kmp_stg_print_bool(buffer, name, __kmp_enable_task_throttling);
 } // __kmp_stg_print_task_throttling
 
+#if KMP_HAVE_MWAIT || KMP_HAVE_UMWAIT
+// -----------------------------------------------------------------------------
+// KMP_USER_LEVEL_MWAIT
+
+static void __kmp_stg_parse_user_level_mwait(char const *name,
+                                             char const *value, void *data) {
+  __kmp_stg_parse_bool(name, value, &__kmp_user_level_mwait);
+} // __kmp_stg_parse_user_level_mwait
+
+static void __kmp_stg_print_user_level_mwait(kmp_str_buf_t *buffer,
+                                             char const *name, void *data) {
+  __kmp_stg_print_bool(buffer, name, __kmp_user_level_mwait);
+} // __kmp_stg_print_user_level_mwait
+
+// -----------------------------------------------------------------------------
+// KMP_MWAIT_HINTS
+
+static void __kmp_stg_parse_mwait_hints(char const *name, char const *value,
+                                        void *data) {
+  __kmp_stg_parse_int(name, value, 0, INT_MAX, &__kmp_mwait_hints);
+} // __kmp_stg_parse_mwait_hints
+
+static void __kmp_stg_print_mwait_hints(kmp_str_buf_t *buffer, char const *name,
+                                        void *data) {
+  __kmp_stg_print_int(buffer, name, __kmp_mwait_hints);
+} // __kmp_stg_print_mwait_hints
+
+#endif // KMP_HAVE_MWAIT || KMP_HAVE_UMWAIT
+
 // -----------------------------------------------------------------------------
 // OMP_DISPLAY_ENV
 
 static void __kmp_stg_parse_omp_display_env(char const *name, char const *value,
                                             void *data) {
   if (__kmp_str_match("VERBOSE", 1, value)) {
     __kmp_display_env_verbose = TRUE;
   } else {

 
 #if OMPT_SUPPORT
     {"OMP_TOOL", __kmp_stg_parse_omp_tool, __kmp_stg_print_omp_tool, NULL, 0,
      0},
     {"OMP_TOOL_LIBRARIES", __kmp_stg_parse_omp_tool_libraries,
      __kmp_stg_print_omp_tool_libraries, NULL, 0, 0},
 #endif
 
+#if KMP_HAVE_MWAIT || KMP_HAVE_UMWAIT
+    {"KMP_USER_LEVEL_MWAIT", __kmp_stg_parse_user_level_mwait,
+     __kmp_stg_print_user_level_mwait, NULL, 0, 0},
+    {"KMP_MWAIT_HINTS", __kmp_stg_parse_mwait_hints,
+     __kmp_stg_print_mwait_hints, NULL, 0, 0},
+#endif
     {"", NULL, NULL, NULL, 0, 0}}; // settings
 
 static int const __kmp_stg_count =
     sizeof(__kmp_stg_table) / sizeof(kmp_setting_t);
 
 static inline kmp_setting_t *__kmp_stg_find(char const *name) {
 
   int i;

openmp/runtime/src/kmp_stats.h

#define KMP_FOREACH_DEVELOPER_TIMER(macro, arg)                                \
   macro(KMP_hyper_gather, 0, arg)                                              \
   macro(KMP_hyper_release, 0, arg)                                             \
   macro(KMP_linear_gather, 0, arg)                                             \
   macro(KMP_linear_release, 0, arg)                                            \
   macro(KMP_tree_gather, 0, arg)                                               \
   macro(KMP_tree_release, 0, arg)                                              \
   macro(USER_resume, 0, arg)                                                   \
   macro(USER_suspend, 0, arg)                                                  \
+  macro(USER_mwait, 0, arg)                                                  \
   macro(KMP_allocate_team, 0, arg)                                             \
   macro(KMP_setup_icv_copy, 0, arg)                                            \
   macro(USER_icv_copy, 0, arg)                                                 \
   macro (FOR_static_steal_stolen,                                              \
          stats_flags_e::noUnits | stats_flags_e::noTotal, arg)                 \
   macro (FOR_static_steal_chunks,                                              \
          stats_flags_e::noUnits | stats_flags_e::noTotal, arg)
 #else

openmp/runtime/src/kmp_taskdeps.cpp

KA_TRACE(10, ("__kmpc_omp_wait_deps(exit): T#%d has no blocking "
                   gtid, loc_ref));
 #if OMPT_SUPPORT
     __ompt_taskwait_dep_finish(current_task, taskwait_task_data);
 #endif /* OMPT_SUPPORT */
     return;
   }
 
   int thread_finished = FALSE;
-  kmp_flag_32 flag((std::atomic<kmp_uint32> *)&node.dn.npredecessors, 0U);
+  kmp_flag_32<false, false> flag(
+      (std::atomic<kmp_uint32> *)&node.dn.npredecessors, 0U);
   while (node.dn.npredecessors > 0) {
     flag.execute_tasks(thread, gtid, FALSE,
                        &thread_finished USE_ITT_BUILD_ARG(NULL),
                        __kmp_task_stealing_constraint);
   }
 
 #if OMPT_SUPPORT
   __ompt_taskwait_dep_finish(current_task, taskwait_task_data);
 #endif /* OMPT_SUPPORT */
   KA_TRACE(10, ("__kmpc_omp_wait_deps(exit): T#%d finished waiting : loc=%p\n",
                 gtid, loc_ref));
 }

openmp/runtime/src/kmp_tasking.cpp

 #endif /* USE_ITT_BUILD */
 
     bool must_wait =
         !taskdata->td_flags.team_serial && !taskdata->td_flags.final;
 
     must_wait = must_wait || (thread->th.th_task_team != NULL &&
                               thread->th.th_task_team->tt.tt_found_proxy_tasks);
     if (must_wait) {
-      kmp_flag_32 flag(RCAST(std::atomic<kmp_uint32> *,
-                             &(taskdata->td_incomplete_child_tasks)),
-                       0U);
+      kmp_flag_32<false, false> flag(
+          RCAST(std::atomic<kmp_uint32> *,
       while (KMP_ATOMIC_LD_ACQ(&taskdata->td_incomplete_child_tasks) != 0) {
         flag.execute_tasks(thread, gtid, FALSE,
                            &thread_finished USE_ITT_BUILD_ARG(itt_sync_obj),
                            __kmp_task_stealing_constraint);
       }
     }
 #if USE_ITT_BUILD
     if (itt_sync_obj != NULL)
if (!taskdata->td_flags.team_serial) {
       kmp_task_team_t *task_team = thread->th.th_task_team;
       if (task_team != NULL) {
         if (KMP_TASKING_ENABLED(task_team)) {
 #if OMPT_SUPPORT
           if (UNLIKELY(ompt_enabled.enabled))
             thread->th.ompt_thread_info.ompt_task_yielded = 1;
 #endif
           __kmp_execute_tasks_32(
-              thread, gtid, NULL, FALSE,
+              thread, gtid, (kmp_flag_32<> *)NULL, FALSE,
               &thread_finished USE_ITT_BUILD_ARG(itt_sync_obj),
               __kmp_task_stealing_constraint);
 #if OMPT_SUPPORT
           if (UNLIKELY(ompt_enabled.enabled))
             thread->th.ompt_thread_info.ompt_task_yielded = 0;
 #endif
         }
       }
if (UNLIKELY(ompt_enabled.ompt_callback_sync_region_wait)) {
           ompt_sync_region_taskgroup, ompt_scope_begin, &(my_parallel_data),
           &(my_task_data), codeptr);
     }
 #endif
 
     if (!taskdata->td_flags.team_serial ||
         (thread->th.th_task_team != NULL &&
          thread->th.th_task_team->tt.tt_found_proxy_tasks)) {
-      kmp_flag_32 flag(RCAST(std::atomic<kmp_uint32> *, &(taskgroup->count)),
-                       0U);
+      kmp_flag_32<false, false> flag(
+          RCAST(std::atomic<kmp_uint32> *, &(taskgroup->count)), 0U);
       while (KMP_ATOMIC_LD_ACQ(&taskgroup->count) != 0) {
         flag.execute_tasks(thread, gtid, FALSE,
                            &thread_finished USE_ITT_BUILD_ARG(itt_sync_obj),
                            __kmp_task_stealing_constraint);
       }
     }
     taskdata->td_taskwait_thread = -taskdata->td_taskwait_thread; // end waiting
 
#endif /* USE_ITT_BUILD */
     else {
       KA_TRACE(15,
                ("__kmp_execute_tasks_template: T#%d can't find work\n", gtid));
       return FALSE;
     }
   }
 }
 
+template <bool C, bool S>
 int __kmp_execute_tasks_32(
-    kmp_info_t *thread, kmp_int32 gtid, kmp_flag_32 *flag, int final_spin,
+    kmp_info_t *thread, kmp_int32 gtid, kmp_flag_32<C, S> *flag, int final_spin,
     int *thread_finished USE_ITT_BUILD_ARG(void *itt_sync_obj),
     kmp_int32 is_constrained) {
   return __kmp_execute_tasks_template(
       thread, gtid, flag, final_spin,
       thread_finished USE_ITT_BUILD_ARG(itt_sync_obj), is_constrained);
 }
 
+template <bool C, bool S>
 int __kmp_execute_tasks_64(
-    kmp_info_t *thread, kmp_int32 gtid, kmp_flag_64 *flag, int final_spin,
+    kmp_info_t *thread, kmp_int32 gtid, kmp_flag_64<C, S> *flag, int final_spin,
     int *thread_finished USE_ITT_BUILD_ARG(void *itt_sync_obj),
     kmp_int32 is_constrained) {
   return __kmp_execute_tasks_template(
       thread, gtid, flag, final_spin,
       thread_finished USE_ITT_BUILD_ARG(itt_sync_obj), is_constrained);
 }
 
 int __kmp_execute_tasks_oncore(
     kmp_info_t *thread, kmp_int32 gtid, kmp_flag_oncore *flag, int final_spin,
     int *thread_finished USE_ITT_BUILD_ARG(void *itt_sync_obj),
     kmp_int32 is_constrained) {
   return __kmp_execute_tasks_template(
       thread, gtid, flag, final_spin,
       thread_finished USE_ITT_BUILD_ARG(itt_sync_obj), is_constrained);
 }
 
+template int
+__kmp_execute_tasks_32<false, false>(kmp_info_t *, kmp_int32,
+                                     kmp_flag_32<false, false> *, int,
+                                     int *USE_ITT_BUILD_ARG(void *), kmp_int32);
+
+template int __kmp_execute_tasks_64<false, true>(kmp_info_t *, kmp_int32,
+                                                 kmp_flag_64<false, true> *,
+                                                 int,
+                                                 int *USE_ITT_BUILD_ARG(void *),
+                                                 kmp_int32);
+
+template int __kmp_execute_tasks_64<true, false>(kmp_info_t *, kmp_int32,
+                                                 kmp_flag_64<true, false> *,
+                                                 int,
+                                                 int *USE_ITT_BUILD_ARG(void *),
+                                                 kmp_int32);
+
 // __kmp_enable_tasking: Allocate task team and resume threads sleeping at the
 // next barrier so they can assist in executing enqueued tasks.
 // First thread in allocates the task team atomically.
 static void __kmp_enable_tasking(kmp_task_team_t *task_team,
                                  kmp_info_t *this_thr) {
   kmp_thread_data_t *threads_data;
   int nthreads, i, is_init_thread;
 
void __kmp_task_team_wait(
   if ((task_team != NULL) && KMP_TASKING_ENABLED(task_team)) {
     if (wait) {
       KA_TRACE(20, ("__kmp_task_team_wait: Master T#%d waiting for all tasks "
                     "(for unfinished_threads to reach 0) on task_team = %p\n",
                     __kmp_gtid_from_thread(this_thr), task_team));
       // Worker threads may have dropped through to release phase, but could
       // still be executing tasks. Wait here for tasks to complete. To avoid
       // memory contention, only master thread checks termination condition.
-      kmp_flag_32 flag(RCAST(std::atomic<kmp_uint32> *,
-                             &task_team->tt.tt_unfinished_threads),
-                       0U);
+      kmp_flag_32<false, false> flag(
+          RCAST(std::atomic<kmp_uint32> *,
       flag.wait(this_thr, TRUE USE_ITT_BUILD_ARG(itt_sync_obj));
     }
     // Deactivate the old task team, so that the worker threads will stop
     // referencing it while spinning.
     KA_TRACE(
         20,
         ("__kmp_task_team_wait: Master T#%d deactivating task_team %p: "
          "setting active to false, setting local and team's pointer to NULL\n",
          __kmp_gtid_from_thread(this_thr), task_team));
     KMP_DEBUG_ASSERT(task_team->tt.tt_nproc > 1 ||
                      task_team->tt.tt_found_proxy_tasks == TRUE);
     TCW_SYNC_4(task_team->tt.tt_found_proxy_tasks, FALSE);
     KMP_CHECK_UPDATE(task_team->tt.tt_untied_task_encountered, 0);
     TCW_SYNC_4(task_team->tt.tt_active, FALSE);
     KMP_MB();
 
     TCW_PTR(this_thr->th.th_task_team, NULL);
   }
 }
 
 // __kmp_tasking_barrier:
-// This routine may only called when __kmp_tasking_mode == tskm_extra_barrier.
+// This routine is called only when __kmp_tasking_mode == tskm_extra_barrier.
 // Internal function to execute all tasks prior to a regular barrier or a join
 // barrier. It is a full barrier itself, which unfortunately turns regular
 // barriers into double barriers and join barriers into 1 1/2 barriers.
 void __kmp_tasking_barrier(kmp_team_t *team, kmp_info_t *thread, int gtid) {
   std::atomic<kmp_uint32> *spin = RCAST(
       std::atomic<kmp_uint32> *,
       &team->t.t_task_team[thread->th.th_task_state]->tt.tt_unfinished_threads);
   int flag = FALSE;
   KMP_DEBUG_ASSERT(__kmp_tasking_mode == tskm_extra_barrier);
 
 #if USE_ITT_BUILD
   KMP_FSYNC_SPIN_INIT(spin, NULL);
 #endif /* USE_ITT_BUILD */
-  kmp_flag_32 spin_flag(spin, 0U);
+  kmp_flag_32<false, false> spin_flag(spin, 0U);
   while (!spin_flag.execute_tasks(thread, gtid, TRUE,
                                   &flag USE_ITT_BUILD_ARG(NULL), 0)) {
 #if USE_ITT_BUILD
     // TODO: What about itt_sync_obj??
     KMP_FSYNC_SPIN_PREPARE(RCAST(void *, spin));
 #endif /* USE_ITT_BUILD */
 
     if (TCR_4(__kmp_global.g.g_done)) {

openmp/runtime/src/kmp_wait_release.h

  * The flag_type describes the storage used for the flag.
  */
 enum flag_type {
   flag32, /**< 32 bit flags */
   flag64, /**< 64 bit flags */
   flag_oncore /**< special 64-bit flag for on-core barrier (hierarchical) */
 };
 
+struct flag_properties {
+  unsigned int type : 16;
+  unsigned int reserved : 16;
+};
+
 /*!
  * Base class for wait/release volatile flag
  */
 template <typename P> class kmp_flag_native {
   volatile P *loc;
-  flag_type t;
+  flag_properties t;
 
 public:
   typedef P flag_t;
-  kmp_flag_native(volatile P *p, flag_type ft) : loc(p), t(ft) {}
+  kmp_flag_native(volatile P *p, flag_type ft)
+      : loc(p), t({(unsigned int)ft, 0U}) {}
   volatile P *get() { return loc; }
   void *get_void_p() { return RCAST(void *, CCAST(P *, loc)); }
   void set(volatile P *new_loc) { loc = new_loc; }
-  flag_type get_type() { return t; }
+  flag_type get_type() { return (flag_type)(t.type); }
   P load() { return *loc; }
   void store(P val) { *loc = val; }
 };
 
 /*!
  * Base class for wait/release atomic flag
  */
 template <typename P> class kmp_flag {
   std::atomic<P>
       *loc; /**< Pointer to the flag storage that is modified by another thread
              */
-  flag_type t; /**< "Type" of the flag in loc */
+  flag_properties t; /**< "Type" of the flag in loc */
+
 public:
   typedef P flag_t;
-  kmp_flag(std::atomic<P> *p, flag_type ft) : loc(p), t(ft) {}
+  kmp_flag(std::atomic<P> *p, flag_type ft)
+      : loc(p), t({(unsigned int)ft, 0U}) {}
   /*!
    * @result the pointer to the actual flag
    */
   std::atomic<P> *get() { return loc; }
   /*!
    * @result void* pointer to the actual flag
    */
   void *get_void_p() { return RCAST(void *, loc); }
   /*!
    * @param new_loc in   set loc to point at new_loc
    */
   void set(std::atomic<P> *new_loc) { loc = new_loc; }
   /*!
    * @result the flag_type
    */
-  flag_type get_type() { return t; }
+  flag_type get_type() { return (flag_type)(t.type); }
   /*!
    * @result flag value
    */
   P load() { return loc->load(std::memory_order_acquire); }
   /*!
    * @param val the new flag value to be stored
    */
   void store(P val) { loc->store(val, std::memory_order_release); }
   // Derived classes must provide the following:
   /*
   kmp_info_t * get_waiter(kmp_uint32 i);
   kmp_uint32 get_num_waiters();
   bool done_check();
   bool done_check_val(P old_loc);
   bool notdone_check();
   P internal_release();
   void suspend(int th_gtid);
+  void mwait(int th_gtid);
   void resume(int th_gtid);
   P set_sleeping();
   P unset_sleeping();
   bool is_sleeping();
   bool is_any_sleeping();
   bool is_sleeping_val(P old_loc);
   int execute_tasks(kmp_info_t *this_thr, kmp_int32 gtid, int final_spin,
                     int *thread_finished

 }
 #endif
 
 /* Spin wait loop that first does pause/yield, then sleep. A thread that calls
    __kmp_wait_*  must make certain that another thread calls __kmp_release
    to wake it back up to prevent deadlocks!
 
    NOTE: We may not belong to a team at this point.  */
-template <class C, int final_spin, bool cancellable = false,
-          bool sleepable = true>
+template <class C, bool final_spin, bool Cancellable = false,
+          bool Sleepable = true>
 static inline bool
 __kmp_wait_template(kmp_info_t *this_thr,
                     C *flag USE_ITT_BUILD_ARG(void *itt_sync_obj)) {
 #if USE_ITT_BUILD && USE_ITT_NOTIFY
   volatile void *spin = flag->get();
 #endif
   kmp_uint32 spins;
   int th_gtid;
   int tasks_completed = FALSE;
   int oversubscribed;
 #if !KMP_USE_MONITOR
   kmp_uint64 poll_count;
   kmp_uint64 hibernate_goal;
 #else
   kmp_uint32 hibernate;
 #endif
 
   KMP_FSYNC_SPIN_INIT(spin, NULL);
   if (flag->done_check()) {
     KMP_FSYNC_SPIN_ACQUIRED(CCAST(void *, spin));
     return false;
   }
   th_gtid = this_thr->th.th_info.ds.ds_gtid;
-  if (cancellable) {
+  if (Cancellable) {
     kmp_team_t *team = this_thr->th.th_team;
     if (team && team->t.t_cancel_request == cancel_parallel)
       return true;
   }
 #if KMP_OS_UNIX
   if (final_spin)
     KMP_ATOMIC_ST_REL(&this_thr->th.th_blocking, true);
 #endif
#if KMP_STATS_ENABLED
     // This indicates that the logical "join-barrier" has finished
     if (this_thr->th.th_stats->isIdle() &&
         KMP_GET_THREAD_STATE() == FORK_JOIN_BARRIER) {
       KMP_SET_THREAD_STATE(IDLE);
       KMP_PUSH_PARTITIONED_TIMER(OMP_idle);
     }
 #endif
     // Check if the barrier surrounding this wait loop has been cancelled
-    if (cancellable) {
+    if (Cancellable) {
       kmp_team_t *team = this_thr->th.th_team;
       if (team && team->t.t_cancel_request == cancel_parallel)
         break;
     }
 
     // Don't suspend if KMP_BLOCKTIME is set to "infinite"
     if (__kmp_dflt_blocktime == KMP_MAX_BLOCKTIME &&
         __kmp_pause_status != kmp_soft_paused)
       continue;
 
     // Don't suspend if there is a likelihood of new tasks being spawned.
     if ((task_team != NULL) && TCR_4(task_team->tt.tt_found_tasks))
       continue;
 
 #if KMP_USE_MONITOR
     // If we have waited a bit more, fall asleep
     if (TCR_4(__kmp_global.g.g_time.dt.t_value) < hibernate)
       continue;
 #else
     if (KMP_BLOCKING(hibernate_goal, poll_count++))
       continue;
 #endif
     // Don't suspend if wait loop designated non-sleepable
     // in template parameters
-    if (!sleepable)
+    if (!Sleepable)
       continue;
 
     if (__kmp_dflt_blocktime == KMP_MAX_BLOCKTIME &&
         __kmp_pause_status != kmp_soft_paused)
       continue;
 
+#if KMP_HAVE_MWAIT || KMP_HAVE_UMWAIT
+    if (__kmp_mwait_enabled || __kmp_umwait_enabled) {
+      KF_TRACE(50, ("__kmp_wait_sleep: T#%d using monitor/mwait\n", th_gtid));
+      flag->mwait(th_gtid);
+    } else {
+#endif
       KF_TRACE(50, ("__kmp_wait_sleep: T#%d suspend time reached\n", th_gtid));
-
 #if KMP_OS_UNIX
       if (final_spin)
         KMP_ATOMIC_ST_REL(&this_thr->th.th_blocking, false);
 #endif
       flag->suspend(th_gtid);
 #if KMP_OS_UNIX
       if (final_spin)
         KMP_ATOMIC_ST_REL(&this_thr->th.th_blocking, true);
 #endif
+#if KMP_HAVE_MWAIT || KMP_HAVE_UMWAIT
+    }
+#endif
 
     if (TCR_4(__kmp_global.g.g_done)) {
       if (__kmp_global.g.g_abort)
         __kmp_abort_thread();
       break;
     } else if (__kmp_tasking_mode != tskm_immediate_exec &&
                this_thr->th.th_reap_state == KMP_SAFE_TO_REAP) {
       this_thr->th.th_reap_state = KMP_NOT_SAFE_TO_REAP;
#if KMP_STATS_ENABLED
   }
 #endif
 
 #if KMP_OS_UNIX
   if (final_spin)
     KMP_ATOMIC_ST_REL(&this_thr->th.th_blocking, false);
 #endif
   KMP_FSYNC_SPIN_ACQUIRED(CCAST(void *, spin));
-  if (cancellable) {
+  if (Cancellable) {
     kmp_team_t *team = this_thr->th.th_team;
     if (team && team->t.t_cancel_request == cancel_parallel) {
       if (tasks_completed) {
         // undo the previous decrement of unfinished_threads so that the
         // thread can decrement at the join barrier with no problem
         kmp_task_team_t *task_team = this_thr->th.th_task_team;
         std::atomic<kmp_int32> *unfinished_threads =
             &(task_team->tt.tt_unfinished_threads);
         KMP_ATOMIC_INC(unfinished_threads);
       }
       return true;
     }
   }
   return false;
 }
 
+#if KMP_HAVE_MWAIT || KMP_HAVE_UMWAIT
+// Set up a monitor on the flag variable causing the calling thread to wait in
+// a less active state until the flag variable is modified.
+template <class C>
+static inline void __kmp_mwait_template(int th_gtid, C *flag) {
+  KMP_TIME_DEVELOPER_PARTITIONED_BLOCK(USER_mwait);
+  kmp_info_t *th = __kmp_threads[th_gtid];
+
+  KF_TRACE(30, ("__kmp_mwait_template: T#%d enter for flag = %p\n", th_gtid,
+                flag->get()));
+
+  // User-level mwait is available
+  KMP_DEBUG_ASSERT(__kmp_mwait_enabled || __kmp_umwait_enabled);
+
+  __kmp_suspend_initialize_thread(th);
+  __kmp_lock_suspend_mx(th);
+
+  volatile void *spin = flag->get();
+  void *cacheline = (void *)(kmp_uint64(spin) & ~(CACHE_LINE - 1));
+
+  if (!flag->done_check()) {
+    // Mark thread as no longer active
+    th->th.th_active = FALSE;
+    if (th->th.th_active_in_pool) {
+      th->th.th_active_in_pool = FALSE;
+      KMP_ATOMIC_DEC(&__kmp_thread_pool_active_nth);
+      KMP_DEBUG_ASSERT(TCR_4(__kmp_thread_pool_active_nth) >= 0);
+    }
+    flag->set_sleeping();
+    KF_TRACE(50, ("__kmp_mwait_template: T#%d calling monitor\n", th_gtid));
+#if KMP_HAVE_UMWAIT
+    if (__kmp_umwait_enabled) {
+      __kmp_umonitor(cacheline);
+    }
+#elif KMP_HAVE_MWAIT
+    if (__kmp_mwait_enabled) {
+      __kmp_mm_monitor(cacheline, 0, 0);
+    }
+#endif
+    // To avoid a race, check flag between 'monitor' and 'mwait'. A write to
+    // the address could happen after the last time we checked and before
+    // monitoring started, in which case monitor can't detect the change.
+    if (flag->done_check())
+      flag->unset_sleeping();
+    else {
+      // if flag changes here, wake-up happens immediately
+      TCW_PTR(th->th.th_sleep_loc, (void *)flag);
+      __kmp_unlock_suspend_mx(th);
+      KF_TRACE(50, ("__kmp_mwait_template: T#%d calling mwait\n", th_gtid));
+#if KMP_HAVE_UMWAIT
+      if (__kmp_umwait_enabled) {
+        __kmp_umwait(1, 100); // to do: enable ctrl via hints, backoff counter
+      }
+#elif KMP_HAVE_MWAIT
+      if (__kmp_mwait_enabled) {
+        __kmp_mm_mwait(0, __kmp_mwait_hints);
+      }
+#endif
+      KF_TRACE(50, ("__kmp_mwait_template: T#%d mwait done\n", th_gtid));
+      __kmp_lock_suspend_mx(th);
+      // Clean up sleep info; doesn't matter how/why this thread stopped waiting
+      if (flag->is_sleeping())
+        flag->unset_sleeping();
+      TCW_PTR(th->th.th_sleep_loc, NULL);
+    }
+    // Mark thread as active again
+    th->th.th_active = TRUE;
+    if (TCR_4(th->th.th_in_pool)) {
+      KMP_ATOMIC_INC(&__kmp_thread_pool_active_nth);
+      th->th.th_active_in_pool = TRUE;
+    }
+  } // Drop out to main wait loop to check flag, handle tasks, etc.
+  __kmp_unlock_suspend_mx(th);
+  KF_TRACE(30, ("__kmp_mwait_template: T#%d exit\n", th_gtid));
+}
+#endif // KMP_HAVE_MWAIT || KMP_HAVE_UMWAIT
+
 /* Release any threads specified as waiting on the flag by releasing the flag
    and resume the waiting thread if indicated by the sleep bit(s). A thread that
    calls __kmp_wait_template must call this function to wake up the potentially
    sleeping thread and prevent deadlocks!  */
 template <class C> static inline void __kmp_release_template(C *flag) {
 #ifdef KMP_DEBUG
   int gtid = TCR_4(__kmp_init_gtid) ? __kmp_get_gtid() : -1;
 #endif
static inline flag_t test_then_or(volatile flag_t *f, flag_t v) {
     return KMP_TEST_THEN_OR64(f, v);
   }
   static inline flag_t test_then_and(volatile flag_t *f, flag_t v) {
     return KMP_TEST_THEN_AND64(f, v);
   }
 };
 
 // Basic flag that does not use C11 Atomics
-template <typename FlagType>
+template <typename FlagType, bool Sleepable>
 class kmp_basic_flag_native : public kmp_flag_native<FlagType> {
   typedef flag_traits<FlagType> traits_type;
   FlagType checker; /**< Value to compare flag to to check if flag has been
                        released. */
   kmp_info_t
       *waiting_threads[1]; /**< Array of threads sleeping on this thread. */
   kmp_uint32
       num_waiting_threads; /**< Number of threads sleeping on this thread. */
public:
    */
   void set_waiter(kmp_info_t *thr) {
     waiting_threads[0] = thr;
     num_waiting_threads = 1;
   }
   /*!
    * @result true if the flag object has been released.
    */
-  bool done_check() { return traits_type::tcr(*(this->get())) == checker; }
+  bool done_check() {
+    if (Sleepable)
+      return (traits_type::tcr(*(this->get())) & ~KMP_BARRIER_SLEEP_STATE) ==
+             checker;
+    else
+      return traits_type::tcr(*(this->get())) == checker;
+  }
   /*!
    * @param old_loc in   old value of flag
    * @result true if the flag's old value indicates it was released.
    */
   bool done_check_val(FlagType old_loc) { return old_loc == checker; }
   /*!
    * @result true if the flag object is not yet released.
    * Used in __kmp_wait_template like:
public:
    * Test whether there are threads sleeping on the flag.
    */
   bool is_sleeping() { return is_sleeping_val(*(this->get())); }
   bool is_any_sleeping() { return is_sleeping_val(*(this->get())); }
   kmp_uint8 *get_stolen() { return NULL; }
   enum barrier_type get_bt() { return bs_last_barrier; }
 };
 
-template <typename FlagType> class kmp_basic_flag : public kmp_flag<FlagType> {
+template <typename FlagType, bool Sleepable>
+class kmp_basic_flag : public kmp_flag<FlagType> {
   typedef flag_traits<FlagType> traits_type;
   FlagType checker; /**< Value to compare flag to to check if flag has been
                        released. */
   kmp_info_t
       *waiting_threads[1]; /**< Array of threads sleeping on this thread. */
   kmp_uint32
       num_waiting_threads; /**< Number of threads sleeping on this thread. */
 public:
public:
    */
   void set_waiter(kmp_info_t *thr) {
     waiting_threads[0] = thr;
     num_waiting_threads = 1;
   }
   /*!
    * @result true if the flag object has been released.
    */
-  bool done_check() { return this->load() == checker; }
+  bool done_check() {
+    if (Sleepable)
+      return (this->load() & ~KMP_BARRIER_SLEEP_STATE) == checker;
+    else
+      return this->load() == checker;
+  }
   /*!
    * @param old_loc in   old value of flag
    * @result true if the flag's old value indicates it was released.
    */
   bool done_check_val(FlagType old_loc) { return old_loc == checker; }
   /*!
    * @result true if the flag object is not yet released.
    * Used in __kmp_wait_template like:
public:
    * Test whether there are threads sleeping on the flag.
    */
   bool is_sleeping() { return is_sleeping_val(this->load()); }
   bool is_any_sleeping() { return is_sleeping_val(this->load()); }
   kmp_uint8 *get_stolen() { return NULL; }
   enum barrier_type get_bt() { return bs_last_barrier; }
 };
 
-class kmp_flag_32 : public kmp_basic_flag<kmp_uint32> {
+template <bool Cancellable, bool Sleepable>
+class kmp_flag_32 : public kmp_basic_flag<kmp_uint32, Sleepable> {
 public:
-  kmp_flag_32(std::atomic<kmp_uint32> *p) : kmp_basic_flag<kmp_uint32>(p) {}
+  kmp_flag_32(std::atomic<kmp_uint32> *p)
+      : kmp_basic_flag<kmp_uint32, Sleepable>(p) {}
   kmp_flag_32(std::atomic<kmp_uint32> *p, kmp_info_t *thr)
-      : kmp_basic_flag<kmp_uint32>(p, thr) {}
+      : kmp_basic_flag<kmp_uint32, Sleepable>(p, thr) {}
   kmp_flag_32(std::atomic<kmp_uint32> *p, kmp_uint32 c)
-      : kmp_basic_flag<kmp_uint32>(p, c) {}
+      : kmp_basic_flag<kmp_uint32, Sleepable>(p, c) {}
   void suspend(int th_gtid) { __kmp_suspend_32(th_gtid, this); }
+#if KMP_HAVE_MWAIT || KMP_HAVE_UMWAIT
+  void mwait(int th_gtid) { __kmp_mwait_32(th_gtid, this); }
+#endif
   void resume(int th_gtid) { __kmp_resume_32(th_gtid, this); }
   int execute_tasks(kmp_info_t *this_thr, kmp_int32 gtid, int final_spin,
                     int *thread_finished USE_ITT_BUILD_ARG(void *itt_sync_obj),
                     kmp_int32 is_constrained) {
     return __kmp_execute_tasks_32(
         this_thr, gtid, this, final_spin,
         thread_finished USE_ITT_BUILD_ARG(itt_sync_obj), is_constrained);
   }
-  void wait(kmp_info_t *this_thr,
+  bool wait(kmp_info_t *this_thr,
             int final_spin USE_ITT_BUILD_ARG(void *itt_sync_obj)) {
     if (final_spin)
-      __kmp_wait_template<kmp_flag_32, TRUE>(
+      return __kmp_wait_template<kmp_flag_32, TRUE, Cancellable, Sleepable>(
           this_thr, this USE_ITT_BUILD_ARG(itt_sync_obj));
     else
-      __kmp_wait_template<kmp_flag_32, FALSE>(
+      return __kmp_wait_template<kmp_flag_32, FALSE, Cancellable, Sleepable>(
           this_thr, this USE_ITT_BUILD_ARG(itt_sync_obj));
   }
   void release() { __kmp_release_template(this); }
   flag_type get_ptr_type() { return flag32; }
 };
 
-class kmp_flag_64 : public kmp_basic_flag_native<kmp_uint64> {
+template <bool Cancellable, bool Sleepable>
+class kmp_flag_64 : public kmp_basic_flag_native<kmp_uint64, Sleepable> {
 public:
-  kmp_flag_64(volatile kmp_uint64 *p) : kmp_basic_flag_native<kmp_uint64>(p) {}
+  kmp_flag_64(volatile kmp_uint64 *p)
+      : kmp_basic_flag_native<kmp_uint64, Sleepable>(p) {}
   kmp_flag_64(volatile kmp_uint64 *p, kmp_info_t *thr)
-      : kmp_basic_flag_native<kmp_uint64>(p, thr) {}
+      : kmp_basic_flag_native<kmp_uint64, Sleepable>(p, thr) {}
   kmp_flag_64(volatile kmp_uint64 *p, kmp_uint64 c)
-      : kmp_basic_flag_native<kmp_uint64>(p, c) {}
+      : kmp_basic_flag_native<kmp_uint64, Sleepable>(p, c) {}
   void suspend(int th_gtid) { __kmp_suspend_64(th_gtid, this); }
+#if KMP_HAVE_MWAIT || KMP_HAVE_UMWAIT
+  void mwait(int th_gtid) { __kmp_mwait_64(th_gtid, this); }
+#endif
   void resume(int th_gtid) { __kmp_resume_64(th_gtid, this); }
   int execute_tasks(kmp_info_t *this_thr, kmp_int32 gtid, int final_spin,
                     int *thread_finished USE_ITT_BUILD_ARG(void *itt_sync_obj),
                     kmp_int32 is_constrained) {
     return __kmp_execute_tasks_64(
         this_thr, gtid, this, final_spin,
         thread_finished USE_ITT_BUILD_ARG(itt_sync_obj), is_constrained);
   }
-  void wait(kmp_info_t *this_thr,
+  bool wait(kmp_info_t *this_thr,
             int final_spin USE_ITT_BUILD_ARG(void *itt_sync_obj)) {
     if (final_spin)
-      __kmp_wait_template<kmp_flag_64, TRUE>(
-          this_thr, this USE_ITT_BUILD_ARG(itt_sync_obj));
-    else
-      __kmp_wait_template<kmp_flag_64, FALSE>(
-          this_thr, this USE_ITT_BUILD_ARG(itt_sync_obj));
-  }
-  bool wait_cancellable_nosleep(kmp_info_t *this_thr,
-                                int final_spin
-                                    USE_ITT_BUILD_ARG(void *itt_sync_obj)) {
-    bool retval = false;
-    if (final_spin)
-      retval = __kmp_wait_template<kmp_flag_64, TRUE, true, false>(
+      return __kmp_wait_template<kmp_flag_64, TRUE, Cancellable, Sleepable>(
           this_thr, this USE_ITT_BUILD_ARG(itt_sync_obj));
     else
-      retval = __kmp_wait_template<kmp_flag_64, FALSE, true, false>(
+      return __kmp_wait_template<kmp_flag_64, FALSE, Cancellable, Sleepable>(
           this_thr, this USE_ITT_BUILD_ARG(itt_sync_obj));
-    return retval;
   }
   void release() { __kmp_release_template(this); }
   flag_type get_ptr_type() { return flag64; }
 };
 
 // Hierarchical 64-bit on-core barrier instantiation
 class kmp_flag_oncore : public kmp_flag_native<kmp_uint64> {
   kmp_uint64 checker;
public:
   bool notdone_check() {
     // Calculate flag_switch
     if (this_thr->th.th_bar[bt].bb.wait_flag == KMP_BARRIER_SWITCH_TO_OWN_FLAG)
       flag_switch = true;
     if (byteref(get(), offset) != 1 && !flag_switch)
       return true;
     else if (flag_switch) {
       this_thr->th.th_bar[bt].bb.wait_flag = KMP_BARRIER_SWITCHING;
-      kmp_flag_64 flag(&this_thr->th.th_bar[bt].bb.b_go,
+      kmp_flag_64<> flag(&this_thr->th.th_bar[bt].bb.b_go,
                          (kmp_uint64)KMP_BARRIER_STATE_BUMP);
       __kmp_wait_64(this_thr, &flag, TRUE USE_ITT_BUILD_ARG(itt_sync_obj));
     }
     return false;
   }
   void internal_release() {
     // Other threads can write their own bytes simultaneously.
     if (__kmp_dflt_blocktime == KMP_MAX_BLOCKTIME) {
       byteref(get(), offset) = 1;
if (final_spin)
       __kmp_wait_template<kmp_flag_oncore, TRUE>(
           this_thr, this USE_ITT_BUILD_ARG(itt_sync_obj));
     else
       __kmp_wait_template<kmp_flag_oncore, FALSE>(
           this_thr, this USE_ITT_BUILD_ARG(itt_sync_obj));
   }
   void release() { __kmp_release_template(this); }
   void suspend(int th_gtid) { __kmp_suspend_oncore(th_gtid, this); }
+#if KMP_HAVE_MWAIT || KMP_HAVE_UMWAIT
+  void mwait(int th_gtid) { __kmp_mwait_oncore(th_gtid, this); }
+#endif
   void resume(int th_gtid) { __kmp_resume_oncore(th_gtid, this); }
   int execute_tasks(kmp_info_t *this_thr, kmp_int32 gtid, int final_spin,
                     int *thread_finished USE_ITT_BUILD_ARG(void *itt_sync_obj),
                     kmp_int32 is_constrained) {
     return __kmp_execute_tasks_oncore(
         this_thr, gtid, this, final_spin,
         thread_finished USE_ITT_BUILD_ARG(itt_sync_obj), is_constrained);
   }
   kmp_uint8 *get_stolen() { return NULL; }
   enum barrier_type get_bt() { return bt; }
   flag_type get_ptr_type() { return flag_oncore; }
 };
 
 // Used to wake up threads, volatile void* flag is usually the th_sleep_loc
 // associated with int gtid.
 static inline void __kmp_null_resume_wrapper(int gtid, volatile void *flag) {
   if (!flag)
     return;
 
-  switch (RCAST(kmp_flag_64 *, CCAST(void *, flag))->get_type()) {
+  switch (RCAST(kmp_flag_64<> *, CCAST(void *, flag))->get_type()) {
   case flag32:
-    __kmp_resume_32(gtid, NULL);
+    __kmp_resume_32(gtid, (kmp_flag_32<> *)NULL);
     break;
   case flag64:
-    __kmp_resume_64(gtid, NULL);
+    __kmp_resume_64(gtid, (kmp_flag_64<> *)NULL);
     break;
   case flag_oncore:
-    __kmp_resume_oncore(gtid, NULL);
+    __kmp_resume_oncore(gtid, (kmp_flag_oncore *)NULL);
     break;
   }
 }
 
 /*!
 @}
 */
 
 #endif // KMP_WAIT_RELEASE_H

openmp/runtime/src/kmp_wait_release.cpp

 /*
  * kmp_wait_release.cpp -- Wait/Release implementation
  */
 
 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "kmp_wait_release.h"
 
-void __kmp_wait_64(kmp_info_t *this_thr, kmp_flag_64 *flag,
+void __kmp_wait_64(kmp_info_t *this_thr, kmp_flag_64<> *flag,
                    int final_spin USE_ITT_BUILD_ARG(void *itt_sync_obj)) {
   if (final_spin)
-    __kmp_wait_template<kmp_flag_64, TRUE>(
+    __kmp_wait_template<kmp_flag_64<>, TRUE>(
         this_thr, flag USE_ITT_BUILD_ARG(itt_sync_obj));
   else
-    __kmp_wait_template<kmp_flag_64, FALSE>(
+    __kmp_wait_template<kmp_flag_64<>, FALSE>(
         this_thr, flag USE_ITT_BUILD_ARG(itt_sync_obj));
 }
 
-void __kmp_release_64(kmp_flag_64 *flag) { __kmp_release_template(flag); }
+void __kmp_release_64(kmp_flag_64<> *flag) { __kmp_release_template(flag); }
+
+#if KMP_HAVE_MWAIT || KMP_HAVE_UMWAIT
+template <bool C, bool S>
+void __kmp_mwait_32(int th_gtid, kmp_flag_32<C, S> *flag) {
+  __kmp_mwait_template(th_gtid, flag);
+}
+template <bool C, bool S>
+void __kmp_mwait_64(int th_gtid, kmp_flag_64<C, S> *flag) {
+  __kmp_mwait_template(th_gtid, flag);
+}
+void __kmp_mwait_oncore(int th_gtid, kmp_flag_oncore *flag) {
+  __kmp_mwait_template(th_gtid, flag);
+}
+
+template void __kmp_mwait_32<false, false>(int, kmp_flag_32<false, false> *);
+template void __kmp_mwait_64<false, true>(int, kmp_flag_64<false, true> *);
+template void __kmp_mwait_64<true, false>(int, kmp_flag_64<true, false> *);
+#endif

openmp/runtime/src/z_Linux_util.cpp

static inline void __kmp_suspend_template(int th_gtid, C *flag) {
   int status;
   typename C::flag_t old_spin;
 
   KF_TRACE(30, ("__kmp_suspend_template: T#%d enter for flag = %p\n", th_gtid,
                 flag->get()));
 
   __kmp_suspend_initialize_thread(th);
 
-  status = pthread_mutex_lock(&th->th.th_suspend_mx.m_mutex);
-  KMP_CHECK_SYSFAIL("pthread_mutex_lock", status);
+  __kmp_lock_suspend_mx(th);
 
   KF_TRACE(10, ("__kmp_suspend_template: T#%d setting sleep bit for spin(%p)\n",
                 th_gtid, flag->get()));
 
   /* TODO: shouldn't this use release semantics to ensure that
      __kmp_suspend_initialize_thread gets called first? */
   old_spin = flag->set_sleeping();
   if (__kmp_dflt_blocktime == KMP_MAX_BLOCKTIME &&
       __kmp_pause_status != kmp_soft_paused) {
     flag->unset_sleeping();
-    status = pthread_mutex_unlock(&th->th.th_suspend_mx.m_mutex);
-    KMP_CHECK_SYSFAIL("pthread_mutex_unlock", status);
+    __kmp_unlock_suspend_mx(th);
     return;
   }
   KF_TRACE(5, ("__kmp_suspend_template: T#%d set sleep bit for spin(%p)==%x,"
                " was %x\n",
                th_gtid, flag->get(), flag->load(), old_spin));
 
   if (flag->done_check_val(old_spin)) {
     old_spin = flag->unset_sleeping();
#if USE_SUSPEND_TIMEOUT
       status = pthread_cond_timedwait(&th->th.th_suspend_cv.c_cond,
                                       &th->th.th_suspend_mx.m_mutex, &now);
 #else
       KF_TRACE(15, ("__kmp_suspend_template: T#%d about to perform"
                     " pthread_cond_wait\n",
                     th_gtid));
       status = pthread_cond_wait(&th->th.th_suspend_cv.c_cond,
                                  &th->th.th_suspend_mx.m_mutex);
-#endif
+#endif // USE_SUSPEND_TIMEOUT
 
       if ((status != 0) && (status != EINTR) && (status != ETIMEDOUT)) {
         KMP_SYSFAIL("pthread_cond_wait", status);
       }
 #ifdef KMP_DEBUG
       if (status == ETIMEDOUT) {
         if (flag->is_sleeping()) {
           KF_TRACE(100,
#ifdef DEBUG_SUSPEND
   {
     char buffer[128];
     __kmp_print_cond(buffer, &th->th.th_suspend_cv);
     __kmp_printf("__kmp_suspend_template: T#%d has awakened: %s\n", th_gtid,
                  buffer);
   }
 #endif
 
-  status = pthread_mutex_unlock(&th->th.th_suspend_mx.m_mutex);
-  KMP_CHECK_SYSFAIL("pthread_mutex_unlock", status);
+  __kmp_unlock_suspend_mx(th);
   KF_TRACE(30, ("__kmp_suspend_template: T#%d exit\n", th_gtid));
 }
 
-void __kmp_suspend_32(int th_gtid, kmp_flag_32 *flag) {
+template <bool C, bool S>
+void __kmp_suspend_32(int th_gtid, kmp_flag_32<C, S> *flag) {
   __kmp_suspend_template(th_gtid, flag);
 }
-void __kmp_suspend_64(int th_gtid, kmp_flag_64 *flag) {
+template <bool C, bool S>
+void __kmp_suspend_64(int th_gtid, kmp_flag_64<C, S> *flag) {
   __kmp_suspend_template(th_gtid, flag);
 }
 void __kmp_suspend_oncore(int th_gtid, kmp_flag_oncore *flag) {
   __kmp_suspend_template(th_gtid, flag);
 }
 
+template void __kmp_suspend_32<false, false>(int, kmp_flag_32<false, false> *);
+template void __kmp_suspend_64<false, true>(int, kmp_flag_64<false, true> *);
+template void __kmp_suspend_64<true, false>(int, kmp_flag_64<true, false> *);
+
 /* This routine signals the thread specified by target_gtid to wake up
    after setting the sleep bit indicated by the flag argument to FALSE.
    The target thread must already have called __kmp_suspend_template() */
 template <class C>
 static inline void __kmp_resume_template(int target_gtid, C *flag) {
   KMP_TIME_DEVELOPER_PARTITIONED_BLOCK(USER_resume);
   kmp_info_t *th = __kmp_threads[target_gtid];
   int status;
 
 #ifdef KMP_DEBUG
   int gtid = TCR_4(__kmp_init_gtid) ? __kmp_get_gtid() : -1;
 #endif
 
   KF_TRACE(30, ("__kmp_resume_template: T#%d wants to wakeup T#%d enter\n",
                 gtid, target_gtid));
   KMP_DEBUG_ASSERT(gtid != target_gtid);
 
   __kmp_suspend_initialize_thread(th);
-
-  status = pthread_mutex_lock(&th->th.th_suspend_mx.m_mutex);
-  KMP_CHECK_SYSFAIL("pthread_mutex_lock", status);
+  __kmp_lock_suspend_mx(th);
 
   if (!flag) { // coming from __kmp_null_resume_wrapper
     flag = (C *)CCAST(void *, th->th.th_sleep_loc);
   }
 
   // First, check if the flag is null or its type has changed. If so, someone
   // else woke it up.
   if (!flag || flag->get_type() != flag->get_ptr_type()) { // get_ptr_type
-    // simply shows what
-    // flag was cast to
+    // simply shows what flag was cast to
     KF_TRACE(5, ("__kmp_resume_template: T#%d exiting, thread T#%d already "
                  "awake: flag(%p)\n",
                  gtid, target_gtid, NULL));
-    status = pthread_mutex_unlock(&th->th.th_suspend_mx.m_mutex);
-    KMP_CHECK_SYSFAIL("pthread_mutex_unlock", status);
+    __kmp_unlock_suspend_mx(th);
     return;
   } else { // if multiple threads are sleeping, flag should be internally
     // referring to a specific thread here
     typename C::flag_t old_spin = flag->unset_sleeping();
     if (!flag->is_sleeping_val(old_spin)) {
       KF_TRACE(5, ("__kmp_resume_template: T#%d exiting, thread T#%d already "
                    "awake: flag(%p): "
                    "%u => %u\n",
                    gtid, target_gtid, flag->get(), old_spin, flag->load()));
-      status = pthread_mutex_unlock(&th->th.th_suspend_mx.m_mutex);
-      KMP_CHECK_SYSFAIL("pthread_mutex_unlock", status);
+      __kmp_unlock_suspend_mx(th);
       return;
     }
     KF_TRACE(5, ("__kmp_resume_template: T#%d about to wakeup T#%d, reset "
                  "sleep bit for flag's loc(%p): "
                  "%u => %u\n",
                  gtid, target_gtid, flag->get(), old_spin, flag->load()));
   }
   TCW_PTR(th->th.th_sleep_loc, NULL);
 
 #ifdef DEBUG_SUSPEND
   {
     char buffer[128];
     __kmp_print_cond(buffer, &th->th.th_suspend_cv);
     __kmp_printf("__kmp_resume_template: T#%d resuming T#%d: %s\n", gtid,
                  target_gtid, buffer);
   }
 #endif
   status = pthread_cond_signal(&th->th.th_suspend_cv.c_cond);
   KMP_CHECK_SYSFAIL("pthread_cond_signal", status);
-  status = pthread_mutex_unlock(&th->th.th_suspend_mx.m_mutex);
-  KMP_CHECK_SYSFAIL("pthread_mutex_unlock", status);
+  __kmp_unlock_suspend_mx(th);
   KF_TRACE(30, ("__kmp_resume_template: T#%d exiting after signaling wake up"
                 " for T#%d\n",
                 gtid, target_gtid));
 }
 
-void __kmp_resume_32(int target_gtid, kmp_flag_32 *flag) {
+template <bool C, bool S>
+void __kmp_resume_32(int target_gtid, kmp_flag_32<C, S> *flag) {
   __kmp_resume_template(target_gtid, flag);
 }
-void __kmp_resume_64(int target_gtid, kmp_flag_64 *flag) {
+template <bool C, bool S>
+void __kmp_resume_64(int target_gtid, kmp_flag_64<C, S> *flag) {
   __kmp_resume_template(target_gtid, flag);
 }
 void __kmp_resume_oncore(int target_gtid, kmp_flag_oncore *flag) {
   __kmp_resume_template(target_gtid, flag);
 }
 
+template void __kmp_resume_32<false, true>(int, kmp_flag_32<false, true> *);
+template void __kmp_resume_64<false, true>(int, kmp_flag_64<false, true> *);
+
 #if KMP_USE_MONITOR
 void __kmp_resume_monitor() {
   KMP_TIME_DEVELOPER_PARTITIONED_BLOCK(USER_resume);
   int status;
 #ifdef KMP_DEBUG
   int gtid = TCR_4(__kmp_init_gtid) ? __kmp_get_gtid() : -1;
   KF_TRACE(30, ("__kmp_resume_monitor: T#%d wants to wakeup T#%d enter\n", gtid,
                 KMP_GTID_MONITOR));

openmp/runtime/src/z_Windows_NT_util.cpp

static inline void __kmp_suspend_template(int th_gtid, C *flag) {
   kmp_info_t *th = __kmp_threads[th_gtid];
   int status;
   typename C::flag_t old_spin;
 
   KF_TRACE(30, ("__kmp_suspend_template: T#%d enter for flag's loc(%p)\n",
                 th_gtid, flag->get()));
 
   __kmp_suspend_initialize_thread(th);
-  __kmp_win32_mutex_lock(&th->th.th_suspend_mx);
+  __kmp_lock_suspend_mx(th);
 
   KF_TRACE(10, ("__kmp_suspend_template: T#%d setting sleep bit for flag's"
                 " loc(%p)\n",
                 th_gtid, flag->get()));
 
   /* TODO: shouldn't this use release semantics to ensure that
      __kmp_suspend_initialize_thread gets called first? */
   old_spin = flag->set_sleeping();
   if (__kmp_dflt_blocktime == KMP_MAX_BLOCKTIME &&
       __kmp_pause_status != kmp_soft_paused) {
     flag->unset_sleeping();
-    __kmp_win32_mutex_unlock(&th->th.th_suspend_mx);
+    __kmp_unlock_suspend_mx(th);
     return;
   }
 
   KF_TRACE(5, ("__kmp_suspend_template: T#%d set sleep bit for flag's"
                " loc(%p)==%d\n",
                th_gtid, flag->get(), *(flag->get())));
 
   if (flag->done_check_val(old_spin)) {
if (deactivated) {
       th->th.th_active = TRUE;
       if (TCR_4(th->th.th_in_pool)) {
         KMP_ATOMIC_INC(&__kmp_thread_pool_active_nth);
         th->th.th_active_in_pool = TRUE;
       }
     }
   }
 
-  __kmp_win32_mutex_unlock(&th->th.th_suspend_mx);
-
+  __kmp_unlock_suspend_mx(th);
   KF_TRACE(30, ("__kmp_suspend_template: T#%d exit\n", th_gtid));
 }
 
-void __kmp_suspend_32(int th_gtid, kmp_flag_32 *flag) {
+template <bool C, bool S>
+void __kmp_suspend_32(int th_gtid, kmp_flag_32<C, S> *flag) {
   __kmp_suspend_template(th_gtid, flag);
 }
-void __kmp_suspend_64(int th_gtid, kmp_flag_64 *flag) {
+template <bool C, bool S>
+void __kmp_suspend_64(int th_gtid, kmp_flag_64<C, S> *flag) {
   __kmp_suspend_template(th_gtid, flag);
 }
 void __kmp_suspend_oncore(int th_gtid, kmp_flag_oncore *flag) {
   __kmp_suspend_template(th_gtid, flag);
 }
 
+template void __kmp_suspend_32<false, false>(int, kmp_flag_32<false, false> *);
+template void __kmp_suspend_64<false, true>(int, kmp_flag_64<false, true> *);
+template void __kmp_suspend_64<true, false>(int, kmp_flag_64<true, false> *);
+
 /* This routine signals the thread specified by target_gtid to wake up
    after setting the sleep bit indicated by the flag argument to FALSE */
 template <class C>
 static inline void __kmp_resume_template(int target_gtid, C *flag) {
   kmp_info_t *th = __kmp_threads[target_gtid];
   int status;
 
 #ifdef KMP_DEBUG
   int gtid = TCR_4(__kmp_init_gtid) ? __kmp_get_gtid() : -1;
 #endif
 
   KF_TRACE(30, ("__kmp_resume_template: T#%d wants to wakeup T#%d enter\n",
                 gtid, target_gtid));
 
   __kmp_suspend_initialize_thread(th);
-  __kmp_win32_mutex_lock(&th->th.th_suspend_mx);
+  __kmp_lock_suspend_mx(th);
 
   if (!flag) { // coming from __kmp_null_resume_wrapper
     flag = (C *)th->th.th_sleep_loc;
   }
 
   // First, check if the flag is null or its type has changed. If so, someone
   // else woke it up.
   if (!flag || flag->get_type() != flag->get_ptr_type()) { // get_ptr_type
     // simply shows what
     // flag was cast to
     KF_TRACE(5, ("__kmp_resume_template: T#%d exiting, thread T#%d already "
                  "awake: flag's loc(%p)\n",
                  gtid, target_gtid, NULL));
-    __kmp_win32_mutex_unlock(&th->th.th_suspend_mx);
+    __kmp_unlock_suspend_mx(th);
     return;
   } else {
     typename C::flag_t old_spin = flag->unset_sleeping();
     if (!flag->is_sleeping_val(old_spin)) {
       KF_TRACE(5, ("__kmp_resume_template: T#%d exiting, thread T#%d already "
                    "awake: flag's loc(%p): %u => %u\n",
                    gtid, target_gtid, flag->get(), old_spin, *(flag->get())));
-      __kmp_win32_mutex_unlock(&th->th.th_suspend_mx);
+      __kmp_unlock_suspend_mx(th);
       return;
     }
   }
   TCW_PTR(th->th.th_sleep_loc, NULL);
   KF_TRACE(5, ("__kmp_resume_template: T#%d about to wakeup T#%d, reset sleep "
                "bit for flag's loc(%p)\n",
                gtid, target_gtid, flag->get()));
 
   __kmp_win32_cond_signal(&th->th.th_suspend_cv);
-  __kmp_win32_mutex_unlock(&th->th.th_suspend_mx);
+  __kmp_unlock_suspend_mx(th);
 
   KF_TRACE(30, ("__kmp_resume_template: T#%d exiting after signaling wake up"
                 " for T#%d\n",
                 gtid, target_gtid));
 }
 
-void __kmp_resume_32(int target_gtid, kmp_flag_32 *flag) {
+template <bool C, bool S>
+void __kmp_resume_32(int target_gtid, kmp_flag_32<C, S> *flag) {
   __kmp_resume_template(target_gtid, flag);
 }
-void __kmp_resume_64(int target_gtid, kmp_flag_64 *flag) {
+template <bool C, bool S>
+void __kmp_resume_64(int target_gtid, kmp_flag_64<C, S> *flag) {
   __kmp_resume_template(target_gtid, flag);
 }
 void __kmp_resume_oncore(int target_gtid, kmp_flag_oncore *flag) {
   __kmp_resume_template(target_gtid, flag);
 }
 
+template void __kmp_resume_32<false, true>(int, kmp_flag_32<false, true> *);
+template void __kmp_resume_64<false, true>(int, kmp_flag_64<false, true> *);
+
 void __kmp_yield() { Sleep(0); }
 
 void __kmp_gtid_set_specific(int gtid) {
   if (__kmp_init_gtid) {
     KA_TRACE(50, ("__kmp_gtid_set_specific: T#%d key:%d\n", gtid,
                   __kmp_gtid_threadprivate_key));
     if (!TlsSetValue(__kmp_gtid_threadprivate_key, (LPVOID)(gtid + 1)))
       KMP_FATAL(TLSSetValueFailed);