[OPENMP][NVPTX] Lightweight runtime support for SPMD mode.

Summary:
Implemented simple and lightweight runtime support for SPMD mode-based
constructs. It adds support for L2 sequential parallelism wihtout full
runtime support. Also, patch fixes some use cases for
uninitialized|lightweight runtime.

Reviewers: grokos, kkwli0, Hahnfeld, gtbercea

Subscribers: guansong, openmp-commits

Differential Revision: https://reviews.llvm.org/D51222

git-svn-id: https://llvm.org/svn/llvm-project/openmp/trunk@340944 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 69 insertions, 6 deletions

diff --git a/libomptarget/deviceRTLs/nvptx/src/libcall.cu b/libomptarget/deviceRTLs/nvptx/src/libcall.cu
index 15040db..de493a5 100644
--- a/libomptarget/deviceRTLs/nvptx/src/libcall.cu
+++ b/libomptarget/deviceRTLs/nvptx/src/libcall.cu
@@ -31,6 +31,10 @@ EXTERN double omp_get_wtime(void) {
 }
 
 EXTERN void omp_set_num_threads(int num) {
+  // Ignore it for SPMD mode.
+  if (isSPMDMode())
+    return;
+  assert(isRuntimeInitialized() && "Expected initialized runtime.");
   PRINT(LD_IO, "call omp_set_num_threads(num %d)\n", num);
   if (num <= 0) {
     WARNING0(LW_INPUT, "expected positive num; ignore\n");
@@ -48,6 +52,12 @@ EXTERN int omp_get_num_threads(void) {
 }
 
 EXTERN int omp_get_max_threads(void) {
+  if (isRuntimeUninitialized()) {
+    assert(isSPMDMode() &&
+           "expected SPMD mode only with uninitialized runtime.");
+    // We're already in parallel region.
+    return 1;  // default is 1 thread avail
+  }
   omptarget_nvptx_TaskDescr *currTaskDescr = getMyTopTaskDescriptor();
   int rc = 1; // default is 1 thread avail
   if (!currTaskDescr->InParallelRegion()) {
@@ -60,6 +70,11 @@ EXTERN int omp_get_max_threads(void) {
 }
 
 EXTERN int omp_get_thread_limit(void) {
+  if (isRuntimeUninitialized()) {
+    assert(isSPMDMode() &&
+           "expected SPMD mode only with uninitialized runtime.");
+    return 0;  // default is 0
+  }
   // per contention group.. meaning threads in current team
   omptarget_nvptx_TaskDescr *currTaskDescr = getMyTopTaskDescriptor();
   int rc = currTaskDescr->ThreadLimit();
@@ -82,9 +97,15 @@ EXTERN int omp_get_num_procs(void) {
 
 EXTERN int omp_in_parallel(void) {
   int rc = 0;
-  omptarget_nvptx_TaskDescr *currTaskDescr = getMyTopTaskDescriptor();
-  if (currTaskDescr->InParallelRegion()) {
-    rc = 1;
+  if (isRuntimeUninitialized()) {
+    assert(isSPMDMode() &&
+           "expected SPMD mode only with uninitialized runtime.");
+    rc = 1;  // SPMD mode is always in parallel.
+  } else {
+    omptarget_nvptx_TaskDescr *currTaskDescr = getMyTopTaskDescriptor();
+    if (currTaskDescr->InParallelRegion()) {
+      rc = 1;
+    }
   }
   PRINT(LD_IO, "call omp_in_parallel() returns %d\n", rc);
   return rc;
@@ -102,6 +123,11 @@ EXTERN int omp_in_final(void) {
 
 EXTERN void omp_set_dynamic(int flag) {
   PRINT(LD_IO, "call omp_set_dynamic(%d)\n", flag);
+  if (isRuntimeUninitialized()) {
+    assert(isSPMDMode() &&
+           "expected SPMD mode only with uninitialized runtime.");
+    return;
+  }
 
   omptarget_nvptx_TaskDescr *currTaskDescr = getMyTopTaskDescriptor();
   if (flag) {
@@ -113,6 +139,11 @@ EXTERN void omp_set_dynamic(int flag) {
 
 EXTERN int omp_get_dynamic(void) {
   int rc = 0;
+  if (isRuntimeUninitialized()) {
+    assert(isSPMDMode() &&
+           "expected SPMD mode only with uninitialized runtime.");
+    return rc;
+  }
   omptarget_nvptx_TaskDescr *currTaskDescr = getMyTopTaskDescriptor();
   if (currTaskDescr->IsDynamic()) {
     rc = 1;
@@ -145,6 +176,11 @@ EXTERN int omp_get_max_active_levels(void) {
 }
 
 EXTERN int omp_get_level(void) {
+  if (isRuntimeUninitialized()) {
+    assert(isSPMDMode() &&
+           "expected SPMD mode only with uninitialized runtime.");
+    return omptarget_nvptx_simpleThreadPrivateContext->GetParallelLevel();
+  }
   int level = 0;
   omptarget_nvptx_TaskDescr *currTaskDescr = getMyTopTaskDescriptor();
   ASSERT0(LT_FUSSY, currTaskDescr,
@@ -160,6 +196,11 @@ EXTERN int omp_get_level(void) {
 }
 
 EXTERN int omp_get_active_level(void) {
+  if (isRuntimeUninitialized()) {
+    assert(isSPMDMode() &&
+           "expected SPMD mode only with uninitialized runtime.");
+    return 1;
+  }
   int level = 0; // no active level parallelism
   omptarget_nvptx_TaskDescr *currTaskDescr = getMyTopTaskDescriptor();
   ASSERT0(LT_FUSSY, currTaskDescr,
@@ -177,6 +218,11 @@ EXTERN int omp_get_active_level(void) {
 }
 
 EXTERN int omp_get_ancestor_thread_num(int level) {
+  if (isRuntimeUninitialized()) {
+    assert(isSPMDMode() &&
+           "expected SPMD mode only with uninitialized runtime.");
+    return level == 1 ? GetThreadIdInBlock() : 0;
+  }
   int rc = 0; // default at level 0
   if (level >= 0) {
     int totLevel = omp_get_level();
@@ -220,6 +266,11 @@ EXTERN int omp_get_ancestor_thread_num(int level) {
 }
 
 EXTERN int omp_get_team_size(int level) {
+  if (isRuntimeUninitialized()) {
+    assert(isSPMDMode() &&
+           "expected SPMD mode only with uninitialized runtime.");
+    return level == 1 ? GetNumberOfThreadsInBlock() : 1;
+  }
   int rc = 1; // default at level 0
   if (level >= 0) {
     int totLevel = omp_get_level();
@@ -247,9 +298,16 @@ EXTERN int omp_get_team_size(int level) {
 }
 
 EXTERN void omp_get_schedule(omp_sched_t *kind, int *modifier) {
-  omptarget_nvptx_TaskDescr *currTaskDescr = getMyTopTaskDescriptor();
-  *kind = currTaskDescr->GetRuntimeSched();
-  *modifier = currTaskDescr->RuntimeChunkSize();
+  if (isRuntimeUninitialized()) {
+    assert(isSPMDMode() &&
+           "expected SPMD mode only with uninitialized runtime.");
+    *kind = omp_sched_static;
+    *modifier = 1;
+  } else {
+    omptarget_nvptx_TaskDescr *currTaskDescr = getMyTopTaskDescriptor();
+    *kind = currTaskDescr->GetRuntimeSched();
+    *modifier = currTaskDescr->RuntimeChunkSize();
+  }
   PRINT(LD_IO, "call omp_get_schedule returns sched %d and modif %d\n",
         (int)*kind, *modifier);
 }
@@ -257,6 +315,11 @@ EXTERN void omp_get_schedule(omp_sched_t *kind, int *modifier) {
 EXTERN void omp_set_schedule(omp_sched_t kind, int modifier) {
   PRINT(LD_IO, "call omp_set_schedule(sched %d, modif %d)\n", (int)kind,
         modifier);
+  if (isRuntimeUninitialized()) {
+    assert(isSPMDMode() &&
+           "expected SPMD mode only with uninitialized runtime.");
+    return;
+  }
   if (kind >= omp_sched_static && kind < omp_sched_auto) {
     omptarget_nvptx_TaskDescr *currTaskDescr = getMyTopTaskDescriptor();
     currTaskDescr->SetRuntimeSched(kind);