Resubmit r237954 (MIR Serialization: print and parse LLVM IR using MIR format).

This commit a 3rd attempt at comitting the initial MIR serialization patch.
The first commit (r237708) was reverted in 237730. Then the second commit
(r237954) was reverted in r238007, as the MIR library under CodeGen caused
a circular dependency where the CodeGen library depended on MIR and MIR
library depended on CodeGen.

This commit has fixed the dependencies between CodeGen and MIR by
reorganizing the MIR serialization code - the code that prints out
MIR has been moved to CodeGen, and the MIR library has been renamed
to MIRParser. Now the CodeGen library doesn't depend on the
MIRParser library, thus the circular dependency no longer exists.

--Original Commit Message--

MIR Serialization: print and parse LLVM IR using MIR format.

This commit is the initial commit for the MIR serialization project.
It creates a new library under CodeGen called 'MIR'. This new
library adds a new machine function pass that prints out the LLVM IR
using the MIR format. This pass is then added as a last pass when a
'stop-after' option is used in llc. The new library adds the initial
functionality for parsing of MIR files as well. This commit also
extends the llc tool so that it can recognize and parse MIR input files.

Reviewers: Duncan P. N. Exon Smith, Matthias Braun, Philip Reames

Differential Revision: http://reviews.llvm.org/D9616 

llvm-svn: 238341

10 files changed, 224 insertions, 8 deletions

diff --git a/llvm/lib/CodeGen/CMakeLists.txt b/llvm/lib/CodeGen/CMakeLists.txt
index 9fc3e0bcec9..6d2af900350 100644
--- a/llvm/lib/CodeGen/CMakeLists.txt
+++ b/llvm/lib/CodeGen/CMakeLists.txt
@@ -71,6 +71,7 @@ add_llvm_library(LLVMCodeGen
   MachineSink.cpp
   MachineTraceMetrics.cpp
   MachineVerifier.cpp
+  MIRPrintingPass.cpp
   OcamlGC.cpp
   OptimizePHIs.cpp
   PHIElimination.cpp
@@ -129,3 +130,4 @@ add_dependencies(LLVMCodeGen intrinsics_gen)
 
 add_subdirectory(SelectionDAG)
 add_subdirectory(AsmPrinter)
+add_subdirectory(MIRParser)
diff --git a/llvm/lib/CodeGen/LLVMBuild.txt b/llvm/lib/CodeGen/LLVMBuild.txt
index fee0347ea65..05905d04dab 100644
--- a/llvm/lib/CodeGen/LLVMBuild.txt
+++ b/llvm/lib/CodeGen/LLVMBuild.txt
@@ -16,7 +16,7 @@
 ;===------------------------------------------------------------------------===;
 
 [common]
-subdirectories = AsmPrinter SelectionDAG
+subdirectories = AsmPrinter SelectionDAG MIRParser
 
 [component_0]
 type = Library
diff --git a/llvm/lib/CodeGen/LLVMTargetMachine.cpp b/llvm/lib/CodeGen/LLVMTargetMachine.cpp
index 610c9f47bac..ff5205801bc 100644
--- a/llvm/lib/CodeGen/LLVMTargetMachine.cpp
+++ b/llvm/lib/CodeGen/LLVMTargetMachine.cpp
@@ -150,12 +150,7 @@ bool LLVMTargetMachine::addPassesToEmitFile(
     return true;
 
   if (StopAfter) {
-    // FIXME: The intent is that this should eventually write out a YAML file,
-    // containing the LLVM IR, the machine-level IR (when stopping after a
-    // machine-level pass), and whatever other information is needed to
-    // deserialize the code and resume compilation.  For now, just write the
-    // LLVM IR.
-    PM.add(createPrintModulePass(Out));
+    PM.add(createPrintMIRPass(outs()));
     return false;
   }
 
diff --git a/llvm/lib/CodeGen/MIRParser/CMakeLists.txt b/llvm/lib/CodeGen/MIRParser/CMakeLists.txt
new file mode 100644
index 00000000000..468f072ed7f
--- /dev/null
+++ b/llvm/lib/CodeGen/MIRParser/CMakeLists.txt
@@ -0,0 +1,5 @@
+add_llvm_library(LLVMMIRParser
+  MIRParser.cpp
+  )
+
+add_dependencies(LLVMMIRParser intrinsics_gen)
diff --git a/llvm/lib/CodeGen/MIRParser/LLVMBuild.txt b/llvm/lib/CodeGen/MIRParser/LLVMBuild.txt
new file mode 100644
index 00000000000..04ae72290f9
--- /dev/null
+++ b/llvm/lib/CodeGen/MIRParser/LLVMBuild.txt
@@ -0,0 +1,22 @@
+;===- ./lib/CodeGen/MIRParser/LLVMBuild.txt --------------------*- Conf -*--===;
+;
+;                     The LLVM Compiler Infrastructure
+;
+; This file is distributed under the University of Illinois Open Source
+; License. See LICENSE.TXT for details.
+;
+;===------------------------------------------------------------------------===;
+;
+; This is an LLVMBuild description file for the components in this subdirectory.
+;
+; For more information on the LLVMBuild system, please see:
+;
+;   http://llvm.org/docs/LLVMBuild.html
+;
+;===------------------------------------------------------------------------===;
+
+[component_0]
+type = Library
+name = MIRParser
+parent = CodeGen
+required_libraries = Core Support Target AsmParser CodeGen
diff --git a/llvm/lib/CodeGen/MIRParser/MIRParser.cpp b/llvm/lib/CodeGen/MIRParser/MIRParser.cpp
new file mode 100644
index 00000000000..8a048c1dfb8
--- /dev/null
+++ b/llvm/lib/CodeGen/MIRParser/MIRParser.cpp
@@ -0,0 +1,90 @@
+//===- MIRParser.cpp - MIR serialization format parser implementation -----===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the class that parses the optional LLVM IR and machine
+// functions that are stored in MIR files.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/MIRParser/MIRParser.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/AsmParser/Parser.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Support/SMLoc.h"
+#include "llvm/Support/SourceMgr.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/YAMLTraits.h"
+#include <memory>
+
+using namespace llvm;
+
+namespace {
+
+/// This class implements the parsing of LLVM IR that's embedded inside a MIR
+/// file.
+class MIRParserImpl {
+  SourceMgr SM;
+  StringRef Filename;
+  LLVMContext &Context;
+
+public:
+  MIRParserImpl(std::unique_ptr<MemoryBuffer> Contents, StringRef Filename,
+                LLVMContext &Context);
+
+  /// Try to parse the optional LLVM module in the MIR file.
+  ///
+  /// Return null if an error occurred while parsing the LLVM module.
+  std::unique_ptr<Module> parseLLVMModule(SMDiagnostic &Error);
+};
+
+} // end anonymous namespace
+
+MIRParserImpl::MIRParserImpl(std::unique_ptr<MemoryBuffer> Contents,
+                             StringRef Filename, LLVMContext &Context)
+    : SM(), Filename(Filename), Context(Context) {
+  SM.AddNewSourceBuffer(std::move(Contents), SMLoc());
+}
+
+std::unique_ptr<Module> MIRParserImpl::parseLLVMModule(SMDiagnostic &Error) {
+  yaml::Input In(SM.getMemoryBuffer(SM.getMainFileID())->getBuffer());
+
+  // Parse the block scalar manually so that we can return unique pointer
+  // without having to go trough YAML traits.
+  if (In.setCurrentDocument()) {
+    if (const auto *BSN =
+            dyn_cast_or_null<yaml::BlockScalarNode>(In.getCurrentNode())) {
+      return parseAssembly(MemoryBufferRef(BSN->getValue(), Filename), Error,
+                           Context);
+    }
+  }
+
+  // Create an new, empty module.
+  return llvm::make_unique<Module>(Filename, Context);
+}
+
+std::unique_ptr<Module> llvm::parseMIRFile(StringRef Filename,
+                                           SMDiagnostic &Error,
+                                           LLVMContext &Context) {
+  auto FileOrErr = MemoryBuffer::getFile(Filename);
+  if (std::error_code EC = FileOrErr.getError()) {
+    Error = SMDiagnostic(Filename, SourceMgr::DK_Error,
+                         "Could not open input file: " + EC.message());
+    return std::unique_ptr<Module>();
+  }
+  return parseMIR(std::move(FileOrErr.get()), Error, Context);
+}
+
+std::unique_ptr<Module> llvm::parseMIR(std::unique_ptr<MemoryBuffer> Contents,
+                                       SMDiagnostic &Error,
+                                       LLVMContext &Context) {
+  auto Filename = Contents->getBufferIdentifier();
+  MIRParserImpl Parser(std::move(Contents), Filename, Context);
+  return Parser.parseLLVMModule(Error);
+}
diff --git a/llvm/lib/CodeGen/MIRParser/Makefile b/llvm/lib/CodeGen/MIRParser/Makefile
new file mode 100644
index 00000000000..c02d18806a9
--- /dev/null
+++ b/llvm/lib/CodeGen/MIRParser/Makefile
@@ -0,0 +1,13 @@
+##===- lib/CodeGen/MIRParser/Makefile ----------------------*- Makefile -*-===##
+#
+#                     The LLVM Compiler Infrastructure
+#
+# This file is distributed under the University of Illinois Open Source
+# License. See LICENSE.TXT for details.
+#
+##===----------------------------------------------------------------------===##
+
+LEVEL = ../../..
+LIBRARYNAME = LLVMMIRParser
+
+include $(LEVEL)/Makefile.common
diff --git a/llvm/lib/CodeGen/MIRPrintingPass.cpp b/llvm/lib/CodeGen/MIRPrintingPass.cpp
new file mode 100644
index 00000000000..c66658cc977
--- /dev/null
+++ b/llvm/lib/CodeGen/MIRPrintingPass.cpp
@@ -0,0 +1,85 @@
+//===- MIRPrintingPass.cpp - Pass that prints out using the MIR format ----===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements a pass that prints out the LLVM module using the MIR
+// serialization format.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/YAMLTraits.h"
+
+using namespace llvm;
+
+namespace llvm {
+namespace yaml {
+
+/// This struct serializes the LLVM IR module.
+template <> struct BlockScalarTraits<Module> {
+  static void output(const Module &Mod, void *Ctxt, raw_ostream &OS) {
+    Mod.print(OS, nullptr);
+  }
+  static StringRef input(StringRef Str, void *Ctxt, Module &Mod) {
+    llvm_unreachable("LLVM Module is supposed to be parsed separately");
+    return "";
+  }
+};
+
+} // end namespace yaml
+} // end namespace llvm
+
+namespace {
+
+/// This pass prints out the LLVM IR to an output stream using the MIR
+/// serialization format.
+struct MIRPrintingPass : public MachineFunctionPass {
+  static char ID;
+  raw_ostream &OS;
+
+  MIRPrintingPass() : MachineFunctionPass(ID), OS(dbgs()) {}
+  MIRPrintingPass(raw_ostream &OS) : MachineFunctionPass(ID), OS(OS) {}
+
+  const char *getPassName() const override { return "MIR Printing Pass"; }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesAll();
+    MachineFunctionPass::getAnalysisUsage(AU);
+  }
+
+  virtual bool runOnMachineFunction(MachineFunction &MF) override {
+    // TODO: Print out the machine function.
+    return false;
+  }
+
+  virtual bool doFinalization(Module &M) override {
+    yaml::Output Out(OS);
+    Out << M;
+    return false;
+  }
+};
+
+char MIRPrintingPass::ID = 0;
+
+} // end anonymous namespace
+
+char &llvm::MIRPrintingPassID = MIRPrintingPass::ID;
+INITIALIZE_PASS(MIRPrintingPass, "mir-printer", "MIR Printer", false, false)
+
+namespace llvm {
+
+MachineFunctionPass *createPrintMIRPass(raw_ostream &OS) {
+  return new MIRPrintingPass(OS);
+}
+
+} // end namespace llvm
diff --git a/llvm/lib/CodeGen/Makefile b/llvm/lib/CodeGen/Makefile
index 4ab3e3c0013..96f7ca58513 100644
--- a/llvm/lib/CodeGen/Makefile
+++ b/llvm/lib/CodeGen/Makefile
@@ -9,7 +9,7 @@
 
 LEVEL = ../..
 LIBRARYNAME = LLVMCodeGen
-PARALLEL_DIRS = SelectionDAG AsmPrinter
+PARALLEL_DIRS = SelectionDAG AsmPrinter MIRParser
 BUILD_ARCHIVE = 1
 
 include $(LEVEL)/Makefile.common
diff --git a/llvm/lib/Support/YAMLTraits.cpp b/llvm/lib/Support/YAMLTraits.cpp
index 90f34f6e232..0d47f37edbd 100644
--- a/llvm/lib/Support/YAMLTraits.cpp
+++ b/llvm/lib/Support/YAMLTraits.cpp
@@ -97,6 +97,10 @@ bool Input::nextDocument() {
   return ++DocIterator != Strm->end();
 }
 
+const Node *Input::getCurrentNode() const {
+  return CurrentNode ? CurrentNode->_node : nullptr;
+}
+
 bool Input::mapTag(StringRef Tag, bool Default) {
   std::string foundTag = CurrentNode->_node->getVerbatimTag();
   if (foundTag.empty()) {