From 3fdd27df0335f0eccc22b86369d8004a837b2530 Mon Sep 17 00:00:00 2001
From: Davide Italiano <davide@freebsd.org>
Date: Fri, 15 Apr 2016 00:07:28 +0000
Subject: [PATCH] [LTO] Add a new splitCodeGen() API which takes a
 TargetMachineFactory.

This will be used in lld to avoid creating TargetMachine in two
different places. See D18999 for a more detailed discussion.

Differential Revision:  http://reviews.llvm.org/D19139

llvm-svn: 266390
---
 llvm/include/llvm/CodeGen/ParallelCG.h | 13 ++++++++
 llvm/lib/CodeGen/ParallelCG.cpp        | 46 +++++++++++++++-----------
 2 files changed, 39 insertions(+), 20 deletions(-)

diff --git a/llvm/include/llvm/CodeGen/ParallelCG.h b/llvm/include/llvm/CodeGen/ParallelCG.h
index 723ea6a9fe22..5932f23e2d92 100644
--- a/llvm/include/llvm/CodeGen/ParallelCG.h
+++ b/llvm/include/llvm/CodeGen/ParallelCG.h
@@ -43,6 +43,19 @@ splitCodeGen(std::unique_ptr<Module> M, ArrayRef<raw_pwrite_stream *> OSs,
              TargetMachine::CodeGenFileType FT = TargetMachine::CGFT_ObjectFile,
              bool PreserveLocals = false);
 
+/// Split M into OSs.size() partitions, and generate code for each.
+/// It is a variant that takes a factory function for the TargetMachine
+/// TMFactory. TMFactory needs to be thread safe on the client side.
+/// See the other splitCodeGen() for a more detailed description.
+///
+/// \returns M if OSs.size() == 1, otherwise returns std::unique_ptr<Module>().
+std::unique_ptr<Module>
+splitCodeGen(std::unique_ptr<Module> M, ArrayRef<raw_pwrite_stream *> OSs,
+             ArrayRef<llvm::raw_pwrite_stream *> BCOSs,
+             const std::function<std::unique_ptr<TargetMachine>()> &TMFactory,
+             TargetMachine::CodeGenFileType FT = TargetMachine::CGFT_ObjectFile,
+             bool PreserveLocals = false);
+
 } // namespace llvm
 
 #endif
diff --git a/llvm/lib/CodeGen/ParallelCG.cpp b/llvm/lib/CodeGen/ParallelCG.cpp
index 1486af14d4bc..7085cb562dff 100644
--- a/llvm/lib/CodeGen/ParallelCG.cpp
+++ b/llvm/lib/CodeGen/ParallelCG.cpp
@@ -25,39 +25,47 @@
 
 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));
-
+static void
+codegen(Module *M, llvm::raw_pwrite_stream &OS,
+        const std::function<std::unique_ptr<TargetMachine>()> &TMFactory,
+        TargetMachine::CodeGenFileType FileType) {
+  std::unique_ptr<TargetMachine> TM = TMFactory();
   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,
-    ArrayRef<llvm::raw_pwrite_stream *> BCOSs, StringRef CPU,
-    StringRef Features, const TargetOptions &Options, Reloc::Model RM,
-    CodeModel::Model CM, CodeGenOpt::Level OL,
-    TargetMachine::CodeGenFileType FileType, bool PreserveLocals) {
+std::unique_ptr<Module>
+llvm::splitCodeGen(std::unique_ptr<Module> M, ArrayRef<raw_pwrite_stream *> OSs,
+                   ArrayRef<llvm::raw_pwrite_stream *> BCOSs, StringRef CPU,
+                   StringRef Features, const TargetOptions &Options,
+                   Reloc::Model RM, CodeModel::Model CM, CodeGenOpt::Level OL,
+                   TargetMachine::CodeGenFileType FileType,
+                   bool PreserveLocals) {
   StringRef TripleStr = M->getTargetTriple();
   std::string ErrMsg;
+
   const Target *TheTarget = TargetRegistry::lookupTarget(TripleStr, ErrMsg);
   if (!TheTarget)
     report_fatal_error(Twine("Target not found: ") + ErrMsg);
+  return splitCodeGen(std::move(M), OSs, BCOSs, [&]() {
+    return std::unique_ptr<TargetMachine>(TheTarget->createTargetMachine(
+        TripleStr, CPU, Features, Options, RM, CM, OL));
+  }, FileType, PreserveLocals);
+}
 
+std::unique_ptr<Module> llvm::splitCodeGen(
+    std::unique_ptr<Module> M, ArrayRef<llvm::raw_pwrite_stream *> OSs,
+    ArrayRef<llvm::raw_pwrite_stream *> BCOSs,
+    const std::function<std::unique_ptr<TargetMachine>()> &TMFactory,
+    TargetMachine::CodeGenFileType FileType, bool PreserveLocals) {
   assert(BCOSs.empty() || BCOSs.size() == OSs.size());
 
   if (OSs.size() == 1) {
     if (!BCOSs.empty())
       WriteBitcodeToFile(M.get(), *BCOSs[0]);
-    codegen(M.get(), *OSs[0], TheTarget, CPU, Features, Options, RM, CM, OL,
-            FileType);
+    codegen(M.get(), *OSs[0], TMFactory, FileType);
     return M;
   }
 
@@ -88,8 +96,7 @@ std::unique_ptr<Module> llvm::splitCodeGen(
           llvm::raw_pwrite_stream *ThreadOS = OSs[ThreadCount++];
           // Enqueue the task
           CodegenThreadPool.async(
-              [TheTarget, CPU, Features, Options, RM, CM, OL, FileType,
-               ThreadOS](const SmallVector<char, 0> &BC) {
+              [&TMFactory, FileType, ThreadOS](const SmallVector<char, 0> &BC) {
                 LLVMContext Ctx;
                 ErrorOr<std::unique_ptr<Module>> MOrErr = parseBitcodeFile(
                     MemoryBufferRef(StringRef(BC.data(), BC.size()),
@@ -99,8 +106,7 @@ std::unique_ptr<Module> llvm::splitCodeGen(
                   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);
+                codegen(MPartInCtx.get(), *ThreadOS, TMFactory, FileType);
               },
               // Pass BC using std::move to ensure that it get moved rather than
               // copied into the thread's context.