[Openmp-commits] [PATCH] D64808: [OPENMMP] Resolve lost LoopTripCnt for subsequent loops in same thread.

[Ron Lieberman via Phabricator via Openmp-commits]

ronlieb created this revision.
ronlieb added reviewers: ABataev, jdoerfert, gregrodgers, JonChesterfield.
Herald added a project: OpenMP.
Herald added a subscriber: openmp-commits.

Remove loopTripCnt from threaded device stack after consuming it.
Added a libomptarget DP message to aid in future debugging and to
validate the added testcase, which only runs in Debug build.


Repository:
  rOMP OpenMP

https://reviews.llvm.org/D64808

Files:
  libomptarget/src/omptarget.cpp
  libomptarget/test/offloading/looptripcnt.c


Index: libomptarget/test/offloading/looptripcnt.c
===================================================================
--- /dev/null
+++ libomptarget/test/offloading/looptripcnt.c
@@ -0,0 +1,41 @@
+// RUN: %libomptarget-compile-aarch64-unknown-linux-gnu && env LIBOMPTARGET_DEBUG=1 %libomptarget-run-aarch64-unknown-linux-gnu 2>&1 | %fcheck-aarch64-unknown-linux-gnu -allow-empty -check-prefix=DEBUG
+// RUN: %libomptarget-compile-powerpc64-ibm-linux-gnu && env LIBOMPTARGET_DEBUG=1 %libomptarget-run-powerpc64-ibm-linux-gnu 2>&1 | %fcheck-powerpc64-ibm-linux-gnu -allow-empty -check-prefix=DEBUG
+// RUN: %libomptarget-compile-powerpc64le-ibm-linux-gnu && env LIBOMPTARGET_DEBUG=1 %libomptarget-run-powerpc64le-ibm-linux-gnu 2>&1 | %fcheck-powerpc64le-ibm-linux-gnu -allow-empty -check-prefix=DEBUG
+// RUN: %libomptarget-compile-x86_64-pc-linux-gnu && env LIBOMPTARGET_DEBUG=1 %libomptarget-run-x86_64-pc-linux-gnu 2>&1 | %fcheck-x86_64-pc-linux-gnu -allow-empty -check-prefix=DEBUG
+// REQUIRES: libomptarget-debug
+
+/*
+  Test for looptripcount being popped from runtime stack.
+*/
+#include <stdio.h>
+#include <omp.h>
+int main()
+{
+  int N = 128;
+  int NN = 1024;
+  int num_teams[NN];
+  int num_threads[NN];
+
+  printf("#pragma omp target teams distribute parallel for thread_limit(4)\n");
+#pragma omp target teams distribute parallel for thread_limit(4)
+  {
+    for (int j = 0; j< N; j++) {
+      num_threads[j] = omp_get_num_threads();
+      num_teams[j] = omp_get_num_teams();
+    }
+  }
+  printf("num_threads %d num_teams %d\n", num_threads[0], num_teams[0]);
+// DEBUG: loop trip count is 128
+  printf("#pragma omp target teams distribute parallel for\n");
+#pragma omp target teams distribute parallel for
+  {
+    for (int j = 0; j< N; j++) {
+      num_threads[j] = omp_get_num_threads();
+      num_teams[j] = omp_get_num_teams();
+    }
+  }
+  printf("num_threads %d num_teams %d\n", num_threads[0], num_teams[0]);
+// DEBUG: loop trip count is 128
+  return 0;
+}
+
Index: libomptarget/src/omptarget.cpp
===================================================================
--- libomptarget/src/omptarget.cpp
+++ libomptarget/src/omptarget.cpp
@@ -732,8 +732,11 @@
   uint64_t ltc = 0;
   TblMapMtx.lock();
   auto I = Device.LoopTripCnt.find(__kmpc_global_thread_num(NULL));
-  if (I != Device.LoopTripCnt.end())
-    std::swap(ltc, I->second);
+  if (I != Device.LoopTripCnt.end()) {
+    ltc = I->second;
+    Device.LoopTripCnt.erase(I);
+    DP("loop trip count is %ld.\n", ltc);
+  }
   TblMapMtx.unlock();
 
   // Launch device execution.


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