Enable gdb and perf event listeners

The following patch ensure that query symbols are properly exposed to
gdb and linux's perf.

Note that the following [1] patch must be applied to perf for proper
unwinding. Afterward, invoke perf as follow:

```
```

[1] https://lore.kernel.org/lkml/20191003105716.GB23291@krava/T/#u

CMakeLists.txt

@@ -11,7 +11,7 @@ option(BUILD_TESTS "Builder unit tests" ON)
 option(FORCE_COLORED_OUTPUT "Always produce ANSI-colored output (GNU/Clang only)." ON)
 
 include(CompilerToolchain)
-find_package(LLVM 8 REQUIRED CONFIG)
+find_package(LLVM 9 REQUIRED CONFIG)
 
 add_subdirectory(src/jitmap)
 add_subdirectory(tools)

src/jitmap/CMakeLists.txt

@@ -18,7 +18,7 @@ target_include_directories(jitmap PUBLIC ${LLVM_INCLUDE_DIRS})
 
 # Required for the jit engine
 set(LLVM_CORE_COMPONENTS support core irreader orcjit vectorize)
-set(LLVM_NATIVE_JIT_COMPONENTS x86codegen x86asmparser x86disassembler x86asmprinter x86desc x86info x86utils)
+set(LLVM_NATIVE_JIT_COMPONENTS x86codegen x86asmparser x86disassembler x86desc x86info x86utils perfjitevents)
 
 llvm_map_components_to_libnames(LLVM_LIBRARIES ${LLVM_CORE_COMPONENTS} ${LLVM_NATIVE_JIT_COMPONENTS})
 target_link_libraries(jitmap ${LLVM_LIBRARIES})

src/jitmap/query/jit.cc

@@ -1,4 +1,8 @@
+#include <memory>
+
 #include <llvm/ADT/Triple.h>
+#include <llvm/Analysis/TargetTransformInfo.h>
+#include <llvm/ExecutionEngine/JITEventListener.h>
 #include <llvm/ExecutionEngine/JITSymbol.h>
 #include <llvm/ExecutionEngine/Orc/ExecutionUtils.h>
 #include <llvm/ExecutionEngine/Orc/JITTargetMachineBuilder.h>
@@ -10,12 +14,13 @@
 #include <llvm/Support/Error.h>
 #include <llvm/Support/TargetSelect.h>
 #include <llvm/Target/TargetMachine.h>
-
-#include <llvm/Analysis/TargetTransformInfo.h>
 #include <llvm/Transforms/IPO.h>
 #include <llvm/Transforms/Utils.h>
 #include <llvm/Transforms/Vectorize.h>
 #include "llvm/Analysis/BasicAliasAnalysis.h"
+#include "llvm/ExecutionEngine/Orc/ObjectTransformLayer.h"
+#include "llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h"
+#include "llvm/ExecutionEngine/SectionMemoryManager.h"
 #include "llvm/Transforms/InstCombine/InstCombine.h"
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Scalar/GVN.h"
@@ -81,10 +86,44 @@ auto InitHostTargetMachineBuilder(const CompilerOptions& opts) {
  return machine_builder;
 }
 
-std::unique_ptr<orc::LLJIT> InitLLJIT(orc::JITTargetMachineBuilder builder,
+// Register a custom ObjectLinkerLayer to support (query) symbols with gdb and perf.
+// LLJIT (via ORC) doesn't support explicitly the llvm::JITEventListener
+// interface. This is the missing glue.
+std::unique_ptr<orc::ObjectLayer> ObjectLinkingLayerFactory(
+ orc::ExecutionSession& execution_session) {
+ auto memory_manager_factory = []() {
+ return std::make_unique<llvm::SectionMemoryManager>();
+ };
+
+ auto linking_layer = std::make_unique<orc::RTDyldObjectLinkingLayer>(
+ execution_session, std::move(memory_manager_factory));
+
+ std::vector<llvm::JITEventListener*> listeners{
+ llvm::JITEventListener::createGDBRegistrationListener(),
+ llvm::JITEventListener::createPerfJITEventListener()};
+
+ // Lambda invoked whenever a new symbol is added.
+ auto notify_loaded = [listeners](orc::VModuleKey key,
+ const llvm::object::ObjectFile& object,
+ const llvm::RuntimeDyld::LoadedObjectInfo& info) {
+ for (auto listener : listeners) {
+ if (listener) listener->notifyObjectLoaded(key, object, info);
+ }
+ };
+
+ linking_layer->setNotifyLoaded(notify_loaded);
+
+ return linking_layer;
+}
+
+std::unique_ptr<orc::LLJIT> InitLLJIT(orc::JITTargetMachineBuilder machine_builder,
  llvm::DataLayout layout,
  const CompilerOptions& options) {
- return ExpectOrRaise(orc::LLJIT::Create(builder, layout, options.compiler_threads));
+ return ExpectOrRaise(orc::LLJITBuilder()
+ .setJITTargetMachineBuilder(machine_builder)
+ .setNumCompileThreads(options.compiler_threads)
+ .setObjectLinkingLayerCreator(ObjectLinkingLayerFactory)
+ .create());
 }
 
 auto AsThreadSafeModule(QueryIRCodeGen::ModuleAndContext module_context) {

tests/query/jit_test.cc

@@ -77,6 +77,10 @@ TEST_F(JitTest, CompileAndExecuteTest) {
 
  AssertQueryResult("a & b & c & d & e", {a, b, c, d, e}, a & b & c & d & e);
  AssertQueryResult("a | b | c | d | e", {a, b, c, d, e}, a | b | c | d | e);
+
+ // Complex re-use of inputs
+ AssertQueryResult("(a | b) & (((!a & c) | (d & b)) ^ (!e & b))", {a, b, c, d, e},
+ (a | b) & (((~a & c) | (d & b)) ^ (~e & b)));
 }
 
 } // namespace query