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

[Teresa Johnson via llvm-commits]

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@@ -20,3 +29,148 @@ TEST(ArenaTest, Basic) {
   Arena::freeArenaList(A);
   EXPECT_EQ(A, nullptr);
 }
+
+TEST_F(ContextTest, Basic) {
+  auto *Ctx = __llvm_ctx_profile_start_context(&Root, 1, 10, 4);
+  EXPECT_NE(Ctx, nullptr);
+  EXPECT_NE(Root.CurrentMem, nullptr);
+  EXPECT_EQ(Root.FirstMemBlock, Root.CurrentMem);
+  EXPECT_EQ(Ctx->size(), sizeof(ContextNode) + 10 * sizeof(uint64_t) +
+                             4 * sizeof(ContextNode *));
+  EXPECT_EQ(Ctx->counters_size(), 10U);
+  EXPECT_EQ(Ctx->callsites_size(), 4U);
+  EXPECT_EQ(__llvm_ctx_profile_current_context_root, &Root);
+  Root.Taken.CheckLocked();
+  EXPECT_FALSE(Root.Taken.TryLock());
+  __llvm_ctx_profile_release_context(&Root);
+  EXPECT_EQ(__llvm_ctx_profile_current_context_root, nullptr);
+  EXPECT_TRUE(Root.Taken.TryLock());
+  Root.Taken.Unlock();
+}
+
+TEST_F(ContextTest, Callsite) {
+  auto *Ctx = __llvm_ctx_profile_start_context(&Root, 1, 10, 4);
+  int OpaqueValue = 0;
+  const bool IsScratch = isScratch(Ctx);
+  EXPECT_FALSE(IsScratch);
+  __llvm_ctx_profile_expected_callee[0] = &OpaqueValue;
+  __llvm_ctx_profile_callsite[0] = &Ctx->subContexts()[2];
+  auto *Subctx = __llvm_ctx_profile_get_context(&OpaqueValue, 2, 3, 1);
+  EXPECT_EQ(Ctx->subContexts()[2], Subctx);
+  EXPECT_EQ(Subctx->counters_size(), 3U);
+  EXPECT_EQ(Subctx->callsites_size(), 1U);
+  EXPECT_EQ(__llvm_ctx_profile_expected_callee[0], nullptr);
+  EXPECT_EQ(__llvm_ctx_profile_callsite[0], nullptr);
+
+  EXPECT_EQ(Subctx->size(), sizeof(ContextNode) + 3 * sizeof(uint64_t) +
+                                1 * sizeof(ContextNode *));
+  __llvm_ctx_profile_release_context(&Root);
+}
+
+TEST_F(ContextTest, ScratchNoCollection) {
+  EXPECT_EQ(__llvm_ctx_profile_current_context_root, nullptr);
+  int OpaqueValue = 0;
+  // this would be the very first function executing this. the TLS is empty,
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teresajohnson wrote:

Can you clarify - I assume it is scratch because start context hasn't been called?

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