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kmp_cancel.cpp
//===----------------------------------------------------------------------===//
//
// 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.h"
#include "kmp_i18n.h"
#include "kmp_io.h"
#include "kmp_str.h"
#if OMPT_SUPPORT
#include "ompt-specific.h"
#endif
kmp_int32 __kmpc_cancel(ident_t *loc_ref, kmp_int32 gtid, kmp_int32 cncl_kind) {
kmp_info_t *this_thr = __kmp_threads[gtid];
KC_TRACE(10, ("__kmpc_cancel: T#%d request %d OMP_CANCELLATION=%d\n", gtid,
cncl_kind, __kmp_omp_cancellation));
KMP_DEBUG_ASSERT(cncl_kind != cancel_noreq);
KMP_DEBUG_ASSERT(cncl_kind == cancel_parallel || cncl_kind == cancel_loop ||
cncl_kind == cancel_sections ||
cncl_kind == cancel_taskgroup);
KMP_DEBUG_ASSERT(__kmp_get_gtid() == gtid);
if (__kmp_omp_cancellation) {
switch (cncl_kind) {
case cancel_parallel:
case cancel_loop:
case cancel_sections:
// cancellation requests for parallel and worksharing constructs
// are handled through the team structure
{
kmp_team_t *this_team = this_thr->th.th_team;
KMP_DEBUG_ASSERT(this_team);
kmp_int32 old = cancel_noreq;
this_team->t.t_cancel_request.compare_exchange_strong(old, cncl_kind);
if (old == cancel_noreq || old == cncl_kind) {
// we do not have a cancellation request in this team or we do have
// one that matches the current request -> cancel
#if OMPT_SUPPORT && OMPT_OPTIONAL
if (ompt_enabled.ompt_callback_cancel) {
ompt_data_t *task_data;
__ompt_get_task_info_internal(0, NULL, &task_data, NULL, NULL,
NULL);
ompt_cancel_flag_t type = ompt_cancel_parallel;
if (cncl_kind == cancel_parallel)
type = ompt_cancel_parallel;
else if (cncl_kind == cancel_loop)
type = ompt_cancel_loop;
else if (cncl_kind == cancel_sections)
type = ompt_cancel_sections;
ompt_callbacks.ompt_callback(ompt_callback_cancel)(
task_data, type | ompt_cancel_activated,
OMPT_GET_RETURN_ADDRESS(0));
}
#endif // OMPT_SUPPORT && OMPT_OPTIONAL
return 1 /* true */;
}
break;
}
case cancel_taskgroup:
// cancellation requests for a task group
// are handled through the taskgroup structure
{
kmp_taskdata_t *task;
kmp_taskgroup_t *taskgroup;
task = this_thr->th.th_current_task;
KMP_DEBUG_ASSERT(task);
taskgroup = task->td_taskgroup;
if (taskgroup) {
kmp_int32 old = cancel_noreq;
taskgroup->cancel_request.compare_exchange_strong(old, cncl_kind);
if (old == cancel_noreq || old == cncl_kind) {
// we do not have a cancellation request in this taskgroup or we do
// have one that matches the current request -> cancel
#if OMPT_SUPPORT && OMPT_OPTIONAL
if (ompt_enabled.ompt_callback_cancel) {
ompt_data_t *task_data;
__ompt_get_task_info_internal(0, NULL, &task_data, NULL, NULL,
NULL);
ompt_callbacks.ompt_callback(ompt_callback_cancel)(
task_data, ompt_cancel_taskgroup | ompt_cancel_activated,
OMPT_GET_RETURN_ADDRESS(0));
}
#endif
return 1 /* true */;
}
} else {
// TODO: what needs to happen here?
// the specification disallows cancellation w/o taskgroups
// so we might do anything here, let's abort for now
KMP_ASSERT(0 /* false */);
}
}
break;
default:
KMP_ASSERT(0 /* false */);
}
}
// ICV OMP_CANCELLATION=false, so we ignored this cancel request
KMP_DEBUG_ASSERT(!__kmp_omp_cancellation);
return 0 /* false */;
}
kmp_int32 __kmpc_cancellationpoint(ident_t *loc_ref, kmp_int32 gtid,
kmp_int32 cncl_kind) {
kmp_info_t *this_thr = __kmp_threads[gtid];
KC_TRACE(10,
("__kmpc_cancellationpoint: T#%d request %d OMP_CANCELLATION=%d\n",
gtid, cncl_kind, __kmp_omp_cancellation));
KMP_DEBUG_ASSERT(cncl_kind != cancel_noreq);
KMP_DEBUG_ASSERT(cncl_kind == cancel_parallel || cncl_kind == cancel_loop ||
cncl_kind == cancel_sections ||
cncl_kind == cancel_taskgroup);
KMP_DEBUG_ASSERT(__kmp_get_gtid() == gtid);
if (__kmp_omp_cancellation) {
switch (cncl_kind) {
case cancel_parallel:
case cancel_loop:
case cancel_sections:
// cancellation requests for parallel and worksharing constructs
// are handled through the team structure
{
kmp_team_t *this_team = this_thr->th.th_team;
KMP_DEBUG_ASSERT(this_team);
if (this_team->t.t_cancel_request) {
if (cncl_kind == this_team->t.t_cancel_request) {
// the request in the team structure matches the type of
// cancellation point so we can cancel
#if OMPT_SUPPORT && OMPT_OPTIONAL
if (ompt_enabled.ompt_callback_cancel) {
ompt_data_t *task_data;
__ompt_get_task_info_internal(0, NULL, &task_data, NULL, NULL,
NULL);
ompt_cancel_flag_t type = ompt_cancel_parallel;
if (cncl_kind == cancel_parallel)
type = ompt_cancel_parallel;
else if (cncl_kind == cancel_loop)
type = ompt_cancel_loop;
else if (cncl_kind == cancel_sections)
type = ompt_cancel_sections;
ompt_callbacks.ompt_callback(ompt_callback_cancel)(
task_data, type | ompt_cancel_detected,
OMPT_GET_RETURN_ADDRESS(0));
}
#endif
return 1 /* true */;
}
KMP_ASSERT(0 /* false */);
} else {
// we do not have a cancellation request pending, so we just
// ignore this cancellation point
return 0;
}
break;
}
case cancel_taskgroup:
// cancellation requests for a task group
// are handled through the taskgroup structure
{
kmp_taskdata_t *task;
kmp_taskgroup_t *taskgroup;
task = this_thr->th.th_current_task;
KMP_DEBUG_ASSERT(task);
taskgroup = task->td_taskgroup;
if (taskgroup) {
// return the current status of cancellation for the taskgroup
#if OMPT_SUPPORT && OMPT_OPTIONAL
if (ompt_enabled.ompt_callback_cancel &&
!!taskgroup->cancel_request) {
ompt_data_t *task_data;
__ompt_get_task_info_internal(0, NULL, &task_data, NULL, NULL,
NULL);
ompt_callbacks.ompt_callback(ompt_callback_cancel)(
task_data, ompt_cancel_taskgroup | ompt_cancel_detected,
OMPT_GET_RETURN_ADDRESS(0));
}
#endif
return !!taskgroup->cancel_request;
} else {
// if a cancellation point is encountered by a task that does not
// belong to a taskgroup, it is OK to ignore it
return 0 /* false */;
}
}
default:
KMP_ASSERT(0 /* false */);
}
}
// ICV OMP_CANCELLATION=false, so we ignore the cancellation point
KMP_DEBUG_ASSERT(!__kmp_omp_cancellation);
return 0 /* false */;
}
kmp_int32 __kmpc_cancel_barrier(ident_t *loc, kmp_int32 gtid) {
int ret = 0 /* false */;
kmp_info_t *this_thr = __kmp_threads[gtid];
kmp_team_t *this_team = this_thr->th.th_team;
KMP_DEBUG_ASSERT(__kmp_get_gtid() == gtid);
// call into the standard barrier
__kmpc_barrier(loc, gtid);
// if cancellation is active, check cancellation flag
if (__kmp_omp_cancellation) {
// depending on which construct to cancel, check the flag and
// reset the flag
switch (KMP_ATOMIC_LD_RLX(&(this_team->t.t_cancel_request))) {
case cancel_parallel:
ret = 1;
// ensure that threads have checked the flag, when
// leaving the above barrier
__kmpc_barrier(loc, gtid);
this_team->t.t_cancel_request = cancel_noreq;
// the next barrier is the fork/join barrier, which
// synchronizes the threads leaving here
break;
case cancel_loop:
case cancel_sections:
ret = 1;
// ensure that threads have checked the flag, when
// leaving the above barrier
__kmpc_barrier(loc, gtid);
this_team->t.t_cancel_request = cancel_noreq;
// synchronize the threads again to make sure we do not have any run-away
// threads that cause a race on the cancellation flag
__kmpc_barrier(loc, gtid);
break;
case cancel_taskgroup:
// this case should not occur
KMP_ASSERT(0 /* false */);
break;
case cancel_noreq:
// do nothing
break;
default:
KMP_ASSERT(0 /* false */);
}
}
return ret;
}
int __kmp_get_cancellation_status(int cancel_kind) {
if (__kmp_omp_cancellation) {
kmp_info_t *this_thr = __kmp_entry_thread();
switch (cancel_kind) {
case cancel_parallel:
case cancel_loop:
case cancel_sections: {
kmp_team_t *this_team = this_thr->th.th_team;
return this_team->t.t_cancel_request == cancel_kind;
}
case cancel_taskgroup: {
kmp_taskdata_t *task;
kmp_taskgroup_t *taskgroup;
task = this_thr->th.th_current_task;
taskgroup = task->td_taskgroup;
return taskgroup && taskgroup->cancel_request;
}
}
}
return 0 /* false */;
}
__kmpc_barrier
KMP_EXPORT void __kmpc_barrier(ident_t *, kmp_int32 global_tid)
Definition kmp_csupport.cpp:756
ident
Definition kmp.h:246