[OpenMP][Tools] Add omp_all_memory support for Archer

The semantic of depend(out:omp_all_memory) is quite similar to taskwait in
that it separates all tasks (with dependency) created before an
all_memory-task from all tasks (with dependency) created after an
all_memory-task.
Only a single of such tasks can execute at a time. Similar to taskwait, we
have a CV (AllMemory[1]) in the generating task to express the dependency
sink semantic of an all_memory-task. In addition, AllMemory[0] describes the
dependency source semantic of an all_memory-task. All tasks with dependency
create an HB-arc towards the sink and terminate an HB-arc from the source.

Since we expect that not many applications will use such dependency, the
support for handling the synchronization semantic is off by default and
can be turned on using ARCHER_OPTION="all_memory=1". The most costly part
is the precautionary posting of an HB-arc towards the sink, which represents
a potentially contentious write from all concurrently executing sibling tasks.
A warning is printed at runtime, when the option is off while such dependency
is observed. In most cases the lazy activation will still lead to false alerts.

Differential Revision: https://reviews.llvm.org/D111895

openmp/tools/archer/README.md

@@ -131,6 +131,18 @@ statement in main!)</td>
 </tr>
 </tbody>
 
+<tbody>
+<tr>
+<td class="org-left">all&#95;memory</td>
+<td class="org-right">0</td>
+<td class="org-left">Turn on tracking and analysis of omp_all_memory
+dependencies. Archer will activate the support automatically when
+such dependency is seen during execution. At this time the analysis
+already missed synchronization semantics, which will lead to false
+reports in most cases.</td>
+</tr>
+</tbody>
+
 <tbody>
 <tr>
 <td class="org-left">report&#95;data&#95;leak</td>

openmp/tools/archer/ompt-tsan.cpp

@@ -63,13 +63,15 @@ class ArcherFlags {
   int enabled{1};
   int report_data_leak{0};
   int ignore_serial{0};
+  std::atomic<int> all_memory{0};
 
   ArcherFlags(const char *env) {
     if (env) {
       std::vector<std::string> tokens;
       std::string token;
       std::string str(env);
       std::istringstream iss(str);
+      int tmp_int;
       while (std::getline(iss, token, ' '))
         tokens.push_back(token);
 
@@ -89,6 +91,10 @@ class ArcherFlags {
           continue;
         if (sscanf(it->c_str(), "ignore_serial=%d", &ignore_serial))
           continue;
+        if (sscanf(it->c_str(), "all_memory=%d", &tmp_int)) {
+          all_memory = tmp_int;
+          continue;
+        }
         std::cerr << "Illegal values for ARCHER_OPTIONS variable: " << token
                   << std::endl;
       }
@@ -451,6 +457,9 @@ struct TaskData final : DataPoolEntry<TaskData> {
   /// this task.
   ompt_tsan_clockid Taskwait{0};
 
+  /// Child tasks use its address to model omp_all_memory dependencies
+  ompt_tsan_clockid AllMemory[2]{0};
+
   /// Whether this task is currently executing a barrier.
   bool InBarrier{false};
 
@@ -506,10 +515,16 @@ struct TaskData final : DataPoolEntry<TaskData> {
   bool isInitial() { return TaskType & ompt_task_initial; }
   bool isTarget() { return TaskType & ompt_task_target; }
 
+  void setAllMemoryDep() { AllMemory[0] = 1; }
+  bool hasAllMemoryDep() { return AllMemory[0]; }
+
   void *GetTaskPtr() { return &Task; }
 
   void *GetTaskwaitPtr() { return &Taskwait; }
 
+  void *GetLastAllMemoryPtr() { return AllMemory; }
+  void *GetNextAllMemoryPtr() { return AllMemory + 1; }
+
   TaskData *Init(TaskData *parent, int taskType) {
     TaskType = taskType;
     Parent = parent;
@@ -855,13 +870,30 @@ static void freeTask(TaskData *task) {
   }
 }
 
+// LastAllMemoryPtr marks the beginning of an all_memory epoch
+// NextAllMemoryPtr marks the end of an all_memory epoch
+// All tasks with depend begin execution after LastAllMemoryPtr
+// and end before NextAllMemoryPtr
 static void releaseDependencies(TaskData *task) {
+  if (archer_flags->all_memory) {
+    if (task->hasAllMemoryDep()) {
+      TsanHappensBefore(task->Parent->GetLastAllMemoryPtr());
+      TsanHappensBefore(task->Parent->GetNextAllMemoryPtr());
+    } else if (task->DependencyCount)
+      TsanHappensBefore(task->Parent->GetNextAllMemoryPtr());
+  }
   for (unsigned i = 0; i < task->DependencyCount; i++) {
     task->Dependencies[i].AnnotateEnd();
   }
 }
 
 static void acquireDependencies(TaskData *task) {
+  if (archer_flags->all_memory) {
+    if (task->hasAllMemoryDep())
+      TsanHappensAfter(task->Parent->GetNextAllMemoryPtr());
+    else if (task->DependencyCount)
+      TsanHappensAfter(task->Parent->GetLastAllMemoryPtr());
+  }
   for (unsigned i = 0; i < task->DependencyCount; i++) {
     task->Dependencies[i].AnnotateBegin();
   }
@@ -983,13 +1015,28 @@ static void ompt_tsan_dependences(ompt_data_t *task_data,
     Data->Dependencies =
         (TaskDependency *)malloc(sizeof(TaskDependency) * ndeps);
     Data->DependencyCount = ndeps;
-    for (int i = 0; i < ndeps; i++) {
+    for (int i = 0, d = 0; i < ndeps; i++, d++) {
+      if (deps[i].dependence_type == ompt_dependence_type_out_all_memory ||
+          deps[i].dependence_type == ompt_dependence_type_inout_all_memory) {
+        Data->setAllMemoryDep();
+        Data->DependencyCount--;
+        if (!archer_flags->all_memory) {
+          printf("The application uses omp_all_memory, but Archer was\n"
+                 "started to not consider omp_all_memory. This can lead\n"
+                 "to false data race alerts.\n"
+                 "Include all_memory=1 in ARCHER_OPTIONS to consider\n"
+                 "omp_all_memory from the beginning.\n");
+          archer_flags->all_memory = 1;
+        }
+        d--;
+        continue;
+      }
       auto ret = Data->Parent->DependencyMap->insert(
           std::make_pair(deps[i].variable.ptr, nullptr));
       if (ret.second) {
         ret.first->second = DependencyData::New();
       }
-      new ((void *)(Data->Dependencies + i))
+      new ((void *)(Data->Dependencies + d))
           TaskDependency(ret.first->second, deps[i].dependence_type);
     }