[compiler-rt] [compiler-rt][ctx_profile] Add the instrumented contextual profiling APIs (PR #89838)

[Mircea Trofin via llvm-commits]

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@@ -38,3 +128,177 @@ void Arena::freeArenaList(Arena *&A) {
   }
   A = nullptr;
 }
+
+inline ContextNode *ContextNode::alloc(char *Place, GUID Guid,
+                                       uint32_t NrCounters,
+                                       uint32_t NrCallsites,
+                                       ContextNode *Next) {
+  assert(reinterpret_cast<uint64_t>(Place) % sizeof(void *) == 0);
+  return new (Place) ContextNode(Guid, NrCounters, NrCallsites, Next);
+}
+
+void ContextNode::reset() {
+  for (uint32_t I = 0; I < NrCounters; ++I)
+    counters()[I] = 0;
+  for (uint32_t I = 0; I < NrCallsites; ++I)
+    for (auto *Next = subContexts()[I]; Next; Next = Next->Next)
+      Next->reset();
+}
+
+// If this is the first time we hit a callsite with this (Guid) particular
+// callee, we need to allocate.
+ContextNode *getCallsiteSlow(uint64_t Guid, ContextNode **InsertionPoint,
+                             uint32_t NrCounters, uint32_t NrCallsites) {
+  auto AllocSize = ContextNode::getAllocSize(NrCounters, NrCallsites);
+  auto *Mem = __llvm_ctx_profile_current_context_root->CurrentMem;
+  char *AllocPlace = Mem->tryBumpAllocate(AllocSize);
+  if (!AllocPlace) {
+    // if we failed to allocate on the current arena, allocate a new arena,
+    // and place it on __llvm_ctx_profile_current_context_root->CurrentMem so we
+    // find it from now on for other cases when we need to getCallsiteSlow.
+    // Note that allocateNewArena will link the allocated memory in the list of
+    // Arenas.
+    __llvm_ctx_profile_current_context_root->CurrentMem = Mem =
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mtrofin wrote:

Which means I missed a test for it - fixed. Thanks for the catch!

https://github.com/llvm/llvm-project/pull/89838