[ctx_profile] Integration test (#92456)

Compile with clang a program that's instrumented for contextual profiling and verify a profile can be collected.

Author: mtrofin

Diff for: compiler-rt/lib/ctx_profile/CMakeLists.txt

@@ -18,3 +18,12 @@ append_list_if(COMPILER_RT_HAS_NOSTDINCXX_FLAG -nostdinc++ EXTRA_FLAGS)
 if(COMPILER_RT_INCLUDE_TESTS)
   add_subdirectory(tests)
 endif()
+
+add_compiler_rt_runtime(clang_rt.ctx_profile
+  STATIC
+  ARCHS ${CTX_PROFILE_SUPPORTED_ARCH}
+  OBJECT_LIBS RTSanitizerCommon RTSanitizerCommonLibc
+  CFLAGS ${EXTRA_FLAGS}
+  SOURCES ${CTX_PROFILE_SOURCES}
+  ADDITIONAL_HEADERS ${CTX_PROFILE_HEADERS}
+  PARENT_TARGET ctx_profile)

Diff for: compiler-rt/test/ctx_profile/TestCases/generate-context.cpp

@@ -0,0 +1,103 @@
+// Simple integration test for contextual instrumentation
+//
+// Copy the header defining ContextNode.
+// RUN: mkdir -p %t_include
+// RUN: cp %llvm_src/include/llvm/ProfileData/CtxInstrContextNode.h %t_include/
+//
+// Compile with ctx instrumentation "on". We treat "theRoot" as callgraph root.
+// RUN: %clangxx %s -lclang_rt.ctx_profile -I%t_include -O2 -o %t.bin -mllvm -profile-context-root=theRoot
+//
+// Run the binary, and observe the profile fetch handler's output.
+// RUN: %t.bin | FileCheck %s
+
+#include "CtxInstrContextNode.h"
+#include <cstdio>
+#include <iostream>
+
+using namespace llvm::ctx_profile;
+extern "C" bool __llvm_ctx_profile_fetch(void *Data,
+                                         bool (*Writer)(void *,
+                                                        const ContextNode &));
+
+// avoid name mangling
+extern "C" {
+__attribute__((noinline)) void someFunction(int I) {
+  if (I % 2)
+    printf("check odd\n");
+  else
+    printf("check even\n");
+}
+
+// block inlining because the pre-inliner otherwise will inline this - it's
+// too small.
+__attribute__((noinline)) void theRoot() {
+  printf("check 1\n");
+  someFunction(1);
+#pragma nounroll
+  for (auto I = 0; I < 2; ++I) {
+    someFunction(I);
+  }
+}
+}
+
+// Make sure the program actually ran correctly.
+// CHECK: check 1
+// CHECK-NEXT: check odd
+// CHECK-NEXT: check even
+// CHECK-NEXT: check odd
+
+void printProfile(const ContextNode &Node, const std::string &Indent,
+                  const std::string &Increment) {
+  std::cout << Indent << "Guid: " << Node.guid() << std::endl;
+  std::cout << Indent << "Entries: " << Node.entrycount() << std::endl;
+  std::cout << Indent << Node.counters_size() << " counters and "
+            << Node.callsites_size() << " callsites" << std::endl;
+  std::cout << Indent << "Counter values: ";
+  for (uint32_t I = 0U; I < Node.counters_size(); ++I)
+    std::cout << Node.counters()[I] << " ";
+  std::cout << std::endl;
+  for (uint32_t I = 0U; I < Node.callsites_size(); ++I)
+    for (const auto *N = Node.subContexts()[I]; N; N = N->next()) {
+      std::cout << Indent << "At Index " << I << ":" << std::endl;
+      printProfile(*N, Indent + Increment, Increment);
+    }
+}
+
+// 8657661246551306189 is theRoot. We expect 2 callsites and 2 counters - one
+// for the entry basic block and one for the loop.
+// 6759619411192316602 is someFunction. We expect all context instances to show
+// the same nr of counters and callsites, but the counters will be different.
+// The first context is for the first callsite with theRoot as parent, and the
+// second counter in someFunction will be 0 (we pass an odd nr, and the other
+// path gets instrumented).
+// The second context is in the loop. We expect 2 entries and each of the
+// branches would be taken once, so the second counter is 1.
+// CHECK-NEXT: Guid: 8657661246551306189
+// CHECK-NEXT: Entries: 1
+// CHECK-NEXT: 2 counters and 3 callsites
+// CHECK-NEXT: Counter values: 1 2
+// CHECK-NEXT: At Index 1:
+// CHECK-NEXT:   Guid: 6759619411192316602
+// CHECK-NEXT:   Entries: 1
+// CHECK-NEXT:   2 counters and 2 callsites
+// CHECK-NEXT:   Counter values: 1 0
+// CHECK-NEXT: At Index 2:
+// CHECK-NEXT:   Guid: 6759619411192316602
+// CHECK-NEXT:   Entries: 2
+// CHECK-NEXT:   2 counters and 2 callsites
+// CHECK-NEXT:   Counter values: 2 1
+
+bool profileWriter() {
+  return __llvm_ctx_profile_fetch(
+      nullptr, +[](void *, const ContextNode &Node) {
+        printProfile(Node, "", "  ");
+        return true;
+      });
+}
+
+int main(int argc, char **argv) {
+  theRoot();
+  // This would be implemented in a specific RPC handler, but here we just call
+  // it directly.
+  return !profileWriter();
+}

Diff for: compiler-rt/test/ctx_profile/lit.cfg.py

@@ -29,3 +29,7 @@ def get_required_attr(config, attr_name):
 config.test_source_root = os.path.dirname(__file__)
 # Default test suffixes.
 config.suffixes = [".c", ".cpp", ".test"]
+
+config.substitutions.append(
+    ("%clangxx ", " ".join([config.clang] + config.cxx_mode_flags) + " ")
+)