Call llc, ld from within onnx-mlir. (#127)

* Call llc, ld from within onnx-mlir.

* Rename EmitLLVMBC -> EmitLib., reorder header files

* Edit comment.

Co-authored-by: Gheorghe-Teodor Bercea <gt.bercea@gmail.com>

src/CMakeLists.txt

@@ -11,6 +11,18 @@ add_executable(onnx-mlir
         MainUtils.cpp
         main.cpp)
 
+# Locate llc, which is needed for translating LLVM bitcode
+# to object file.
+if(NOT EXISTS "${LLVM_PROJ_BUILD}/bin/llc")
+  message(ERROR "Cannot find llc.")
+endif()
+
+# Get the compiler command name, the C++ compiler is needed to to translate
+# object files to shared libraries.
+get_filename_component(CXX_COMPILER_FILENAME ${CMAKE_CXX_COMPILER} NAME)
+configure_file(${CMAKE_CURRENT_SOURCE_DIR}/ExternalUtil.hpp.in
+        ${CMAKE_CURRENT_BINARY_DIR}/ExternalUtil.hpp)
+
 set(ONNX_MLIR_LD_PRELOAD_onnx-mlir "" CACHE STRING "" FORCE)
 whole_archive_link_mlir(onnx-mlir ${MLIRWholeArchiveLibs})
 if(BUILD_SHARED_LIBS)

src/ExternalUtil.hpp.in

@@ -0,0 +1,9 @@
+#pragma once
+#include <string>
+
+namespace onnx_mlir {
+const std::string kLlcPath = "@LLVM_PROJ_BUILD@/bin/llc";
+const std::string kCxxPath = "@CMAKE_CXX_COMPILER@";
+const std::string kCxxFileName = "@CXX_COMPILER_FILENAME@";
+const std::string kRuntimeDirPath = "@CMAKE_BINARY_DIR@/lib";
+}

src/MainUtils.cpp

@@ -8,9 +8,13 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "src/MainUtils.hpp"
+#include <cstdio>
 #include <fcntl.h>
-#include <stdio.h>
+
+#include "llvm/Support/Program.h"
+
+#include "src/ExternalUtil.hpp"
+#include "src/MainUtils.hpp"
 
 #ifdef _WIN32
 #include <io.h>
@@ -43,14 +47,33 @@ void LoadMLIR(string inputFilename, mlir::MLIRContext &context,
   }
 }
 
-void EmitLLVMBitCode(
-    const mlir::OwningModuleRef &module, string outputFilename) {
+void compileModuleToSharedLibrary(
+    const mlir::OwningModuleRef &module, string outputBaseName) {
+  // Write LLVM bitcode.
+  string outputFilename = outputBaseName + ".bc";
   error_code error;
   llvm::raw_fd_ostream moduleBitcodeStream(
       outputFilename, error, llvm::sys::fs::F_None);
   llvm::WriteBitcodeToFile(
       *mlir::translateModuleToLLVMIR(*module), moduleBitcodeStream);
   moduleBitcodeStream.flush();
+
+  // Compile bitcode to object file.
+  std::vector<std::string> llcArgs = {
+      "llc", "-filetype=obj", "-relocation-model=pic", outputFilename};
+  auto llcArgStrRefs =
+      std::vector<llvm::StringRef>(llcArgs.begin(), llcArgs.end());
+  llvm::sys::ExecuteAndWait(kLlcPath, llvm::makeArrayRef(llcArgStrRefs));
+
+  // Link with runtime.
+  // TODO(tjingrant): link with runtime library in LLVM, and make the shared
+  // library more self-contained.
+  std::vector<std::string> cxxArgs = {kCxxFileName, "-shared", "-fPIC",
+      outputBaseName + ".o", "-o", outputBaseName + ".so",
+      "-L" + kRuntimeDirPath, "-lcruntime", "-Wl,-rpath," + kRuntimeDirPath};
+  auto argsArrayRefVector =
+      std::vector<llvm::StringRef>(cxxArgs.begin(), cxxArgs.end());
+  llvm::sys::ExecuteAndWait(kCxxPath, llvm::makeArrayRef(argsArrayRefVector));
 }
 
 void registerDialects() {
@@ -149,11 +172,10 @@ void emitOutputFiles(string outputBaseName, EmissionTargetType emissionTarget,
   // outside the function code at the beginning of the file in which case the
   // elision of these constants is not strictly required. Elision is also not
   // necessary when emitting the .bc file.
-  if (emissionTarget == EmitLLVMBC) {
-    // Write LLVM bitcode to disk.
-    string outputFilename = outputBaseName + ".bc";
-    EmitLLVMBitCode(module, outputFilename);
-    printf("LLVM bitcode written to %s\n", outputFilename.c_str());
+  if (emissionTarget == EmitLib) {
+    // Write LLVM bitcode to disk, compile & link.
+    compileModuleToSharedLibrary(module, outputBaseName);
+    printf("Shared library %s.so has been compiled.", outputBaseName.c_str());
   } else {
     // Emit the version with all constants included.
     outputCode(module, outputBaseName, ".onnx.mlir");

src/MainUtils.hpp

@@ -42,14 +42,14 @@ enum EmissionTargetType {
   EmitONNXIR,
   EmitMLIR,
   EmitLLVMIR,
-  EmitLLVMBC,
+  EmitLib,
 };
 
 void LoadMLIR(std::string inputFilename, mlir::MLIRContext &context,
     mlir::OwningModuleRef &module);
 
-void EmitLLVMBitCode(
-    const mlir::OwningModuleRef &module, std::string outputFilename);
+void compileModuleToSharedLibrary(
+    const mlir::OwningModuleRef &module, std::string outputBaseName);
 
 void registerDialects();
 

src/main.cpp

@@ -31,9 +31,10 @@ int main(int argc, char *argv[]) {
           clEnumVal(
               EmitMLIR, "Lower model to MLIR built-in transformation dialect."),
           clEnumVal(EmitLLVMIR, "Lower model to LLVM IR (LLVM dialect)."),
-          clEnumVal(EmitLLVMBC, "Lower model to LLVM IR and emit (to file) "
-                                "LLVM bitcode for model.")),
-      llvm::cl::init(EmitLLVMBC), llvm::cl::cat(OnnxMlirOptions));
+          clEnumVal(EmitLib, "Lower model to LLVM IR, emit (to file) "
+                             "LLVM bitcode for model, compile and link it to a "
+                             "shared library.")),
+      llvm::cl::init(EmitLib), llvm::cl::cat(OnnxMlirOptions));
 
   llvm::cl::HideUnrelatedOptions(OnnxMlirOptions);
   llvm::cl::ParseCommandLineOptions(

test/backend/test.py

@@ -40,14 +40,6 @@ class DummyBackend(onnx.backend.base.Backend):
         onnx.save(model, "temp_model.onnx")
         # Call frontend to process temp_model.onnx, bit code will be generated.
         execute_commands([ONNX_MLIR, "temp_model.onnx"])
-        # Call llc to generate object file from bitcode.
-        execute_commands(
-            [LLC, "-filetype=obj", "-relocation-model=pic", "temp_model.bc"])
-        # Generate shared library from object file, linking with c runtime.
-        execute_commands([
-            CXX, "-shared", "-fPIC", "temp_model.o", "-o", "temp_model.so",
-            "-L" + RUNTIME_DIR, "-lcruntime", "-Wl,-rpath=" + RUNTIME_DIR,
-        ])
         return ExecutionSession("./temp_model.so", "_dyn_entry_point_main_graph")
 
     @classmethod
@@ -62,7 +54,6 @@ backend_test = onnx.backend.test.BackendTest(DummyBackend, __name__)
 
 # Test directories:
 # https://github.com/onnx/onnx/tree/master/onnx/backend/test/data/node
-
 test_to_enable = [
     # Abs Op:
     "test_abs_cpu",