[ctx_profile] Integration test

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

Author: mtrofin

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)

compiler-rt/test/ctx_profile/TestCases/generate-context.cpp

@@ -0,0 +1,72 @@
+// 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 "the_root" as callgraph root.
+// RUN: %clangxx %s -lclang_rt.ctx_profile -I%t_include -O2 -o %t.bin -mllvm -profile-context-root=the_root
+//
+// 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 &));
+
+extern "C" {
+__attribute__((noinline)) void someFunction() { printf("check 2\n"); }
+
+// block inlining because the pre-inliner otherwise will inline this - it's
+// too small.
+__attribute__((noinline)) void the_root() {
+  printf("check 1\n");
+  someFunction();
+  someFunction();
+}
+}
+
+// Make sure the program actually ran correctly.
+// CHECK: check 1
+// CHECK: check 2
+// CHECK: check 2
+
+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;
+  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);
+    }
+}
+
+// CHECK: Guid: 11065787667334760794
+// CHECK: Entries: 1
+// CHECK: At Index 1:
+// CHECK:   Guid: 6759619411192316602
+// CHECK:   Entries: 1
+// CHECK: At Index 2:
+// CHECK:   Guid: 6759619411192316602
+// CHECK:   Entries: 1
+
+bool profileWriter() {
+  return __llvm_ctx_profile_fetch(
+      nullptr, +[](void *, const ContextNode &Node) {
+        printProfile(Node, "", "  ");
+        return true;
+      });
+}
+
+int main(int argc, char **argv) {
+  the_root();
+  // This would be implemented in a specific RPC handler, but here we just call
+  // it directly.
+  return !profileWriter();
+}

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) + " ")
+)