[Orc] New JIT APIs.

This patch adds a new set of JIT APIs to LLVM. The aim of these new APIs is to
cleanly support a wider range of JIT use cases in LLVM, and encourage the
development and contribution of re-usable infrastructure for LLVM JIT use-cases.

These APIs are intended to live alongside the MCJIT APIs, and should not affect
existing clients.

Included in this patch:

1) New headers in include/llvm/ExecutionEngine/Orc that provide a set of
   components for building JIT infrastructure.
   Implementation code for these headers lives in lib/ExecutionEngine/Orc.

2) A prototype re-implementation of MCJIT (OrcMCJITReplacement) built out of the
   new components.

3) Minor changes to RTDyldMemoryManager needed to support the new components.
   These changes should not impact existing clients.

4) A new flag for lli, -use-orcmcjit, which will cause lli to use the
   OrcMCJITReplacement class as its underlying execution engine, rather than
   MCJIT itself.

Tests to follow shortly.

Special thanks to Michael Ilseman, Pete Cooper, David Blaikie, Eric Christopher,
Justin Bogner, and Jim Grosbach for extensive feedback and discussion.

llvm-svn: 226940

Author: lhames

llvm/include/llvm/ExecutionEngine/ExecutionEngine.h

@@ -143,6 +143,12 @@ class ExecutionEngine {
                                      std::string *ErrorStr,
                                      std::unique_ptr<RTDyldMemoryManager> MCJMM,
                                      std::unique_ptr<TargetMachine> TM);
+
+  static ExecutionEngine *(*OrcMCJITReplacementCtor)(
+                                    std::string *ErrorStr,
+                                    std::unique_ptr<RTDyldMemoryManager> OrcJMM,
+                                    std::unique_ptr<TargetMachine> TM);
+
   static ExecutionEngine *(*InterpCtor)(std::unique_ptr<Module> M,
                                         std::string *ErrorStr);
 
@@ -464,6 +470,7 @@ class ExecutionEngine {
   }
 
 protected:
+  ExecutionEngine() : EEState(*this) {}
   explicit ExecutionEngine(std::unique_ptr<Module> M);
 
   void emitGlobals();
@@ -501,11 +508,15 @@ class EngineBuilder {
   std::string MCPU;
   SmallVector<std::string, 4> MAttrs;
   bool VerifyModules;
+  bool UseOrcMCJITReplacement;
 
   /// InitEngine - Does the common initialization of default options.
   void InitEngine();
 
 public:
+  /// Default constructor for EngineBuilder.
+  EngineBuilder();
+
   /// Constructor for EngineBuilder.
   EngineBuilder(std::unique_ptr<Module> M);
 
@@ -590,6 +601,11 @@ class EngineBuilder {
     return *this;
   }
 
+  // \brief Use OrcMCJITReplacement instead of MCJIT. Off by default.
+  void setUseOrcMCJITReplacement(bool UseOrcMCJITReplacement) {
+    this->UseOrcMCJITReplacement = UseOrcMCJITReplacement;
+  }
+
   TargetMachine *selectTarget();
 
   /// selectTarget - Pick a target either via -march or by guessing the native

llvm/include/llvm/ExecutionEngine/ObjectMemoryBuffer.h

@@ -0,0 +1,63 @@
+//===- ObjectMemoryBuffer.h - SmallVector-backed MemoryBuffrer  -*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares a wrapper class to hold the memory into which an
+// object will be generated.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_EXECUTIONENGINE_OBJECTMEMORYBUFFER_H
+#define LLVM_EXECUTIONENGINE_OBJECTMEMORYBUFFER_H
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/raw_ostream.h"
+
+namespace llvm {
+
+/// \brief SmallVector-backed MemoryBuffer instance.
+///
+/// This class enables efficient construction of MemoryBuffers from SmallVector
+/// instances. This is useful for MCJIT and Orc, where object files are streamed
+/// into SmallVectors, then inspected using ObjectFile (which takes a
+/// MemoryBuffer).
+class ObjectMemoryBuffer : public MemoryBuffer {
+public:
+
+  /// \brief Construct an ObjectMemoryBuffer from the given SmallVector r-value.
+  ///
+  /// FIXME: It'd be nice for this to be a non-templated constructor taking a
+  /// SmallVectorImpl here instead of a templated one taking a SmallVector<N>,
+  /// but SmallVector's move-construction/assignment currently only take
+  /// SmallVectors. If/when that is fixed we can simplify this constructor and
+  /// the following one.
+  ObjectMemoryBuffer(SmallVectorImpl<char> &&SV)
+    : SV(std::move(SV)), BufferName("<in-memory object>") {
+    init(this->SV.begin(), this->SV.end(), false);
+  }
+
+  /// \brief Construct a named ObjectMemoryBuffer from the given SmallVector
+  ///        r-value and StringRef.
+  ObjectMemoryBuffer(SmallVectorImpl<char> &&SV, StringRef Name)
+    : SV(std::move(SV)), BufferName(Name) {
+    init(this->SV.begin(), this->SV.end(), false);
+  }
+
+  const char* getBufferIdentifier() const override { return BufferName.c_str(); }
+
+  BufferKind getBufferKind() const override { return MemoryBuffer_Malloc; }
+
+private:
+  SmallVector<char, 0> SV;
+  std::string BufferName;
+};
+
+} // namespace llvm
+
+#endif

llvm/include/llvm/ExecutionEngine/Orc/CloneSubModule.h

@@ -0,0 +1,44 @@
+//===-- CloneSubModule.h - Utilities for extracting sub-modules -*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Contains utilities for extracting sub-modules. Useful for breaking up modules
+// for lazy jitting.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_EXECUTIONENGINE_ORC_CLONESUBMODULE_H
+#define LLVM_EXECUTIONENGINE_ORC_CLONESUBMODULE_H
+
+#include "llvm/Transforms/Utils/ValueMapper.h"
+#include <functional>
+
+namespace llvm {
+
+class Function;
+class GlobalVariable;
+class Module;
+
+typedef std::function<void(GlobalVariable &, const GlobalVariable &,
+                           ValueToValueMapTy &)> HandleGlobalVariableFtor;
+
+typedef std::function<void(Function &, const Function &, ValueToValueMapTy &)>
+    HandleFunctionFtor;
+
+void copyGVInitializer(GlobalVariable &New, const GlobalVariable &Orig,
+                       ValueToValueMapTy &VMap);
+
+void copyFunctionBody(Function &New, const Function &Orig,
+                      ValueToValueMapTy &VMap);
+
+std::unique_ptr<Module>
+CloneSubModule(const Module &M, HandleGlobalVariableFtor HandleGlobalVariable,
+               HandleFunctionFtor HandleFunction, bool KeepInlineAsm);
+}
+
+#endif // LLVM_EXECUTIONENGINE_ORC_CLONESUBMODULE_H