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[OpenMP] Fix endian bug in hierarchical barrier code #117073

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[OpenMP] Fix endian bug in hierarchical barrier code #117073

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31 changes: 23 additions & 8 deletions openmp/runtime/src/kmp_barrier.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1292,6 +1292,15 @@ static bool __kmp_init_hierarchical_barrier_thread(enum barrier_type bt,
kmp_bstate_t *thr_bar,
kmp_uint32 nproc, int gtid,
int tid, kmp_team_t *team) {
// Helper macro to identify bytes in a kmp_uint64 in an endian-independent
// way. Input 0 results in the byte address of the MSB, input 7 results
// in the byte address of the LSB.
#if defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
#define __kmp_msb_byteoffset(offset) (offset)
#else
#define __kmp_msb_byteoffset(offset) (7 - (offset))
#endif

// Checks to determine if (re-)initialization is needed
bool uninitialized = thr_bar->team == NULL;
bool team_changed = team != thr_bar->team;
Expand All @@ -1306,6 +1315,7 @@ static bool __kmp_init_hierarchical_barrier_thread(enum barrier_type bt,
if (uninitialized || team_sz_changed || tid_changed) {
thr_bar->my_level = thr_bar->depth - 1; // default for primary thread
thr_bar->parent_tid = -1; // default for primary thread
thr_bar->offset = -1; // unused for primary thread
if (!KMP_MASTER_TID(tid)) {
// if not primary thread, find parent thread in hierarchy
kmp_uint32 d = 0;
Expand All @@ -1325,10 +1335,14 @@ static bool __kmp_init_hierarchical_barrier_thread(enum barrier_type bt,
}
++d;
}

kmp_uint32 offset = ((kmp_uint32)tid - thr_bar->parent_tid) /
thr_bar->skip_per_level[thr_bar->my_level];
offset = offset - 1;
KMP_ASSERT(offset < 7);
__kmp_type_convert(__kmp_msb_byteoffset(offset), &(thr_bar->offset));
}
__kmp_type_convert(7 - ((tid - thr_bar->parent_tid) /
(thr_bar->skip_per_level[thr_bar->my_level])),
&(thr_bar->offset));

thr_bar->old_tid = tid;
thr_bar->wait_flag = KMP_BARRIER_NOT_WAITING;
thr_bar->team = team;
Expand All @@ -1350,9 +1364,11 @@ static bool __kmp_init_hierarchical_barrier_thread(enum barrier_type bt,
__kmp_type_convert(nproc - tid - 1, &(thr_bar->leaf_kids));
thr_bar->leaf_state = 0;
for (int i = 0; i < thr_bar->leaf_kids; ++i)
((char *)&(thr_bar->leaf_state))[7 - i] = 1;
((char *)&(thr_bar->leaf_state))[__kmp_msb_byteoffset(i)] = 1;
}
return retval;

#undef __kmp_msb_byteoffset
}

static void __kmp_hierarchical_barrier_gather(
Expand Down Expand Up @@ -1506,8 +1522,7 @@ static void __kmp_hierarchical_barrier_gather(
} 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 + 1);
kmp_flag_oncore flag(&thr_bar->parent_bar->b_arrived, thr_bar->offset);
flag.set_waiter(other_threads[thr_bar->parent_tid]);
flag.release();
}
Expand Down Expand Up @@ -1555,7 +1570,7 @@ static void __kmp_hierarchical_barrier_release(
// Wait on my "offset" bits on parent's b_go flag
thr_bar->wait_flag = KMP_BARRIER_PARENT_FLAG;
kmp_flag_oncore flag(&thr_bar->parent_bar->b_go, KMP_BARRIER_STATE_BUMP,
thr_bar->offset + 1, bt,
thr_bar->offset, bt,
this_thr USE_ITT_BUILD_ARG(itt_sync_obj));
flag.wait(this_thr, TRUE);
if (thr_bar->wait_flag ==
Expand All @@ -1564,7 +1579,7 @@ static void __kmp_hierarchical_barrier_release(
KMP_INIT_BARRIER_STATE); // Reset my b_go flag for next time
} else { // Reset my bits on parent's b_go flag
(RCAST(volatile char *,
&(thr_bar->parent_bar->b_go)))[thr_bar->offset + 1] = 0;
&(thr_bar->parent_bar->b_go)))[thr_bar->offset] = 0;
}
}
thr_bar->wait_flag = KMP_BARRIER_NOT_WAITING;
Expand Down
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