1 files changed, 96 insertions, 0 deletions
diff --git a/contrib/llvm/lib/CodeGen/ParallelCG.cpp b/contrib/llvm/lib/CodeGen/ParallelCG.cpp
new file mode 100644
index 0000000..e73ba02
--- /dev/null
+++ b/contrib/llvm/lib/CodeGen/ParallelCG.cpp
@@ -0,0 +1,96 @@
+//===-- ParallelCG.cpp ----------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines functions that can be used for parallel code generation.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/ParallelCG.h"
+#include "llvm/Bitcode/ReaderWriter.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/LegacyPassManager.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Support/ErrorOr.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/TargetRegistry.h"
+#include "llvm/Support/thread.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Transforms/Utils/SplitModule.h"
+
+using namespace llvm;
+
+static void codegen(Module *M, llvm::raw_pwrite_stream &OS,
+                    const Target *TheTarget, StringRef CPU, StringRef Features,
+                    const TargetOptions &Options, Reloc::Model RM,
+                    CodeModel::Model CM, CodeGenOpt::Level OL,
+                    TargetMachine::CodeGenFileType FileType) {
+  std::unique_ptr<TargetMachine> TM(TheTarget->createTargetMachine(
+      M->getTargetTriple(), CPU, Features, Options, RM, CM, OL));
+
+  legacy::PassManager CodeGenPasses;
+  if (TM->addPassesToEmitFile(CodeGenPasses, OS, FileType))
+    report_fatal_error("Failed to setup codegen");
+  CodeGenPasses.run(*M);
+}
+
+std::unique_ptr<Module>
+llvm::splitCodeGen(std::unique_ptr<Module> M,
+                   ArrayRef<llvm::raw_pwrite_stream *> OSs, StringRef CPU,
+                   StringRef Features, const TargetOptions &Options,
+                   Reloc::Model RM, CodeModel::Model CM, CodeGenOpt::Level OL,
+                   TargetMachine::CodeGenFileType FileType) {
+  StringRef TripleStr = M->getTargetTriple();
+  std::string ErrMsg;
+  const Target *TheTarget = TargetRegistry::lookupTarget(TripleStr, ErrMsg);
+  if (!TheTarget)
+    report_fatal_error(Twine("Target not found: ") + ErrMsg);
+
+  if (OSs.size() == 1) {
+    codegen(M.get(), *OSs[0], TheTarget, CPU, Features, Options, RM, CM,
+            OL, FileType);
+    return M;
+  }
+
+  std::vector<thread> Threads;
+  SplitModule(std::move(M), OSs.size(), [&](std::unique_ptr<Module> MPart) {
+    // We want to clone the module in a new context to multi-thread the codegen.
+    // We do it by serializing partition modules to bitcode (while still on the
+    // main thread, in order to avoid data races) and spinning up new threads
+    // which deserialize the partitions into separate contexts.
+    // FIXME: Provide a more direct way to do this in LLVM.
+    SmallVector<char, 0> BC;
+    raw_svector_ostream BCOS(BC);
+    WriteBitcodeToFile(MPart.get(), BCOS);
+
+    llvm::raw_pwrite_stream *ThreadOS = OSs[Threads.size()];
+    Threads.emplace_back(
+        [TheTarget, CPU, Features, Options, RM, CM, OL, FileType,
+         ThreadOS](const SmallVector<char, 0> &BC) {
+          LLVMContext Ctx;
+          ErrorOr<std::unique_ptr<Module>> MOrErr =
+              parseBitcodeFile(MemoryBufferRef(StringRef(BC.data(), BC.size()),
+                                               "<split-module>"),
+                               Ctx);
+          if (!MOrErr)
+            report_fatal_error("Failed to read bitcode");
+          std::unique_ptr<Module> MPartInCtx = std::move(MOrErr.get());
+
+          codegen(MPartInCtx.get(), *ThreadOS, TheTarget, CPU, Features,
+                  Options, RM, CM, OL, FileType);
+        },
+        // Pass BC using std::move to ensure that it get moved rather than
+        // copied into the thread's context.
+        std::move(BC));
+  });
+
+  for (thread &T : Threads)
+    T.join();
+
+  return {};
+}