Adding MCJIT and MemoryBuffer unit tests

Patch by Daniel Malea.

llvm-svn: 165246

llvm/unittests/ExecutionEngine/CMakeLists.txt

@@ -7,3 +7,4 @@ add_llvm_unittest(ExecutionEngineTests
   )
 
 add_subdirectory(JIT)
+add_subdirectory(MCJIT)

llvm/unittests/ExecutionEngine/MCJIT/CMakeLists.txt

@@ -0,0 +1,25 @@
+set(LLVM_LINK_COMPONENTS
+  asmparser
+  bitreader
+  bitwriter
+  mcjit
+  jit
+  nativecodegen
+  )
+
+set(MCJITTestsSources
+  MCJITTest.cpp
+  SectionMemoryManager.cpp
+  )
+
+if(MSVC)
+  list(APPEND MCJITTestsSources MCJITTests.def)
+endif()
+
+add_llvm_unittest(MCJITTests
+  ${MCJITTestsSources}
+  )
+
+if(MINGW OR CYGWIN)
+  set_property(TARGET MCJITTests PROPERTY LINK_FLAGS -Wl,--export-all-symbols)
+endif()

llvm/unittests/ExecutionEngine/MCJIT/MCJITTest.cpp

@@ -0,0 +1,226 @@
+//===- MCJITTest.cpp - Unit tests for the MCJIT ---------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This test suite verifies basic MCJIT functionality such as making function
+// calls, using global variables, and compiling multpile modules.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ExecutionEngine/MCJIT.h"
+#include "MCJITTestBase.h"
+#include "SectionMemoryManager.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+class MCJITTest : public testing::Test, public MCJITTestBase {
+protected:
+
+  virtual void SetUp() {
+    M.reset(createEmptyModule("<main>"));
+  }
+};
+
+namespace {
+
+// FIXME: In order to JIT an empty module, there needs to be
+// an interface to ExecutionEngine that forces compilation but
+// does require retrieval of a pointer to a function/global.
+/*
+TEST_F(MCJITTest, empty_module) {
+  createJIT(M.take());
+  //EXPECT_NE(0, TheJIT->getObjectImage())
+  //  << "Unable to generate executable loaded object image";
+}
+*/
+
+TEST_F(MCJITTest, global_variable) {
+  SKIP_UNSUPPORTED_PLATFORM;
+
+  int initialValue = 5;
+  GlobalValue *Global = insertGlobalInt32(M.get(), "test_global", initialValue);
+  createJIT(M.take());
+  void *globalPtr =  TheJIT->getPointerToGlobal(Global);
+  EXPECT_TRUE(0 != globalPtr)
+    << "Unable to get pointer to global value from JIT";
+
+  EXPECT_EQ(initialValue, *(int32_t*)globalPtr)
+    << "Unexpected initial value of global";
+}
+
+TEST_F(MCJITTest, add_function) {
+  SKIP_UNSUPPORTED_PLATFORM;
+
+  Function *F = insertAddFunction(M.get());
+  createJIT(M.take());
+  void *addPtr = TheJIT->getPointerToFunction(F);
+  EXPECT_TRUE(0 != addPtr)
+    << "Unable to get pointer to function from JIT";
+
+  int (*AddPtrTy)(int, int) = (int(*)(int, int))(intptr_t)addPtr;
+  EXPECT_EQ(0, AddPtrTy(0, 0));
+  EXPECT_EQ(3, AddPtrTy(1, 2));
+  EXPECT_EQ(-5, AddPtrTy(-2, -3));
+}
+
+TEST_F(MCJITTest, run_main) {
+  SKIP_UNSUPPORTED_PLATFORM;
+
+  int rc = 6;
+  Function *Main = insertMainFunction(M.get(), 6);
+  createJIT(M.take());
+  void *vPtr = TheJIT->getPointerToFunction(Main);
+  EXPECT_TRUE(0 != vPtr)
+    << "Unable to get pointer to main() from JIT";
+
+  int (*FuncPtr)(void) = (int(*)(void))(intptr_t)vPtr;
+  int returnCode = FuncPtr();
+  EXPECT_EQ(returnCode, rc);
+}
+
+TEST_F(MCJITTest, return_global) {
+  SKIP_UNSUPPORTED_PLATFORM;
+
+  int32_t initialNum = 7;
+  GlobalVariable *GV = insertGlobalInt32(M.get(), "myglob", initialNum);
+
+  Function *ReturnGlobal = startFunction<int32_t(void)>(M.get(),
+                                                        "ReturnGlobal");
+  Value *ReadGlobal = Builder.CreateLoad(GV);
+  endFunctionWithRet(ReturnGlobal, ReadGlobal);
+
+  createJIT(M.take());
+  void *rgvPtr = TheJIT->getPointerToFunction(ReturnGlobal);
+  EXPECT_TRUE(0 != rgvPtr);
+
+  int32_t(*FuncPtr)(void) = (int32_t(*)(void))(intptr_t)rgvPtr;
+  EXPECT_EQ(initialNum, FuncPtr())
+    << "Invalid value for global returned from JITted function";
+}
+
+// FIXME: This case fails due to a bug with getPointerToGlobal().
+// The bug is due to MCJIT not having an implementation of getPointerToGlobal()
+// which results in falling back on the ExecutionEngine implementation that
+// allocates a new memory block for the global instead of using the same
+// global variable that is emitted by MCJIT. Hence, the pointer (gvPtr below)
+// has the correct initial value, but updates to the real global (accessed by
+// JITted code) are not propagated. Instead, getPointerToGlobal() should return
+// a pointer into the loaded ObjectImage to reference the emitted global.
+/*
+TEST_F(MCJITTest, increment_global) {
+  SKIP_UNSUPPORTED_PLATFORM;
+
+  int32_t initialNum = 5;
+  Function *IncrementGlobal = startFunction<int32_t(void)>(M.get(), "IncrementGlobal");
+  GlobalVariable *GV = insertGlobalInt32(M.get(), "my_global", initialNum);
+  Value *DerefGV = Builder.CreateLoad(GV);
+  Value *AddResult = Builder.CreateAdd(DerefGV,
+                                       ConstantInt::get(Context, APInt(32, 1)));
+  Builder.CreateStore(AddResult, GV);
+  endFunctionWithRet(IncrementGlobal, AddResult);
+
+  createJIT(M.take());
+  void *gvPtr = TheJIT->getPointerToGlobal(GV);
+  EXPECT_EQ(initialNum, *(int32_t*)gvPtr);
+
+  void *vPtr = TheJIT->getPointerToFunction(IncrementGlobal);
+  EXPECT_TRUE(0 != vPtr)
+    << "Unable to get pointer to main() from JIT";
+
+  int32_t(*FuncPtr)(void) = (int32_t(*)(void))(intptr_t)vPtr;
+
+  for(int i = 1; i < 3; ++i) {
+    int32_t result = FuncPtr();
+    EXPECT_EQ(initialNum + i, result);            // OK
+    EXPECT_EQ(initialNum + i, *(int32_t*)gvPtr);  // FAILS
+  }
+}
+*/
+
+TEST_F(MCJITTest, multiple_functions) {
+  SKIP_UNSUPPORTED_PLATFORM;
+
+  unsigned int numLevels = 23;
+  int32_t innerRetVal= 5;
+
+  Function *Inner = startFunction<int32_t(void)>(M.get(), "Inner");
+  endFunctionWithRet(Inner, ConstantInt::get(Context, APInt(32, innerRetVal)));
+
+  Function *Outer;
+  for (unsigned int i = 0; i < numLevels; ++i) {
+    std::stringstream funcName;
+    funcName << "level_" << i;
+    Outer = startFunction<int32_t(void)>(M.get(), funcName.str());
+    Value *innerResult = Builder.CreateCall(Inner);
+    endFunctionWithRet(Outer, innerResult);
+
+    Inner = Outer;
+  }
+
+  createJIT(M.take());
+  void *vPtr = TheJIT->getPointerToFunction(Outer);
+  EXPECT_TRUE(0 != vPtr)
+    << "Unable to get pointer to outer function from JIT";
+
+  int32_t(*FuncPtr)(void) = (int32_t(*)(void))(intptr_t)vPtr;
+  EXPECT_EQ(innerRetVal, FuncPtr())
+    << "Incorrect result returned from function";
+}
+
+// FIXME: ExecutionEngine has no support empty modules
+/*
+TEST_F(MCJITTest, multiple_empty_modules) {
+  SKIP_UNSUPPORTED_PLATFORM;
+
+  createJIT(M.take());
+  // JIT-compile
+  EXPECT_NE(0, TheJIT->getObjectImage())
+    << "Unable to generate executable loaded object image";
+
+  TheJIT->addModule(createEmptyModule("<other module>"));
+  TheJIT->addModule(createEmptyModule("<other other module>"));
+
+  // JIT again
+  EXPECT_NE(0, TheJIT->getObjectImage())
+    << "Unable to generate executable loaded object image";
+}
+*/
+
+// FIXME: MCJIT must support multiple modules
+/*
+TEST_F(MCJITTest, multiple_modules) {
+  SKIP_UNSUPPORTED_PLATFORM;
+
+  Function *Callee = insertAddFunction(M.get());
+  createJIT(M.take());
+
+  // caller function is defined in a different module
+  M.reset(createEmptyModule("<caller module>"));
+
+  Function *CalleeRef = insertExternalReferenceToFunction(M.get(), Callee);
+  Function *Caller = insertSimpleCallFunction(M.get(), CalleeRef);
+
+  TheJIT->addModule(M.take());
+
+  // get a function pointer in a module that was not used in EE construction
+  void *vPtr = TheJIT->getPointerToFunction(Caller);
+  EXPECT_NE(0, vPtr)
+    << "Unable to get pointer to caller function from JIT";
+
+  int(*FuncPtr)(int, int) = (int(*)(int, int))(intptr_t)vPtr;
+  EXPECT_EQ(0, FuncPtr(0, 0));
+  EXPECT_EQ(30, FuncPtr(10, 20));
+  EXPECT_EQ(-30, FuncPtr(-10, -20));
+
+  // ensure caller is destroyed before callee (free use before def)
+  M.reset();
+}
+*/
+
+}

llvm/unittests/ExecutionEngine/MCJIT/MCJITTestBase.h

@@ -0,0 +1,245 @@
+//===- MCJITTestBase.h - Common base class for MCJIT Unit tests  ----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This class implements common functionality required by the MCJIT unit tests,
+// as well as logic to skip tests on unsupported architectures and operating
+// systems.
+//
+//===----------------------------------------------------------------------===//
+
+
+#ifndef MCJIT_TEST_BASE_H
+#define MCJIT_TEST_BASE_H
+
+#include "llvm/ADT/Triple.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Config/config.h"
+#include "llvm/ExecutionEngine/ExecutionEngine.h"
+#include "llvm/Function.h"
+#include "llvm/IRBuilder.h"
+#include "llvm/LLVMContext.h"
+#include "llvm/Module.h"
+#include "llvm/Support/CodeGen.h"
+#include "llvm/Support/Host.h"
+#include "llvm/Support/TargetSelect.h"
+#include "llvm/TypeBuilder.h"
+
+#include "SectionMemoryManager.h"
+
+// Used to skip tests on unsupported architectures and operating systems.
+// To skip a test, add this macro at the top of a test-case in a suite that
+// inherits from MCJITTestBase. See MCJITTest.cpp for examples.
+#define SKIP_UNSUPPORTED_PLATFORM \
+  do \
+    if (!ArchSupportsMCJIT() || !OSSupportsMCJIT()) \
+      return; \
+  while(0);
+
+namespace llvm {
+
+class MCJITTestBase {
+protected:
+
+  MCJITTestBase()
+    : OptLevel(CodeGenOpt::None)
+    , RelocModel(Reloc::Default)
+    , CodeModel(CodeModel::Default)
+    , MArch("")
+    , Builder(Context)
+    , MM(new SectionMemoryManager)
+    , HostTriple(LLVM_HOSTTRIPLE)
+  {
+    InitializeNativeTarget();
+    InitializeNativeTargetAsmPrinter();
+
+#ifdef LLVM_ON_WIN32
+    // On Windows, generate ELF objects by specifying "-elf" in triple
+    HostTriple += "-elf";
+#endif // LLVM_ON_WIN32
+    HostTriple = Triple::normalize(HostTriple);
+
+    // The architectures below are known to be compatible with MCJIT as they
+    // are copied from test/ExecutionEngine/MCJIT/lit.local.cfg and should be
+    // kept in sync.
+    SupportedArchs.push_back(Triple::arm);
+    SupportedArchs.push_back(Triple::mips);
+    SupportedArchs.push_back(Triple::x86);
+    SupportedArchs.push_back(Triple::x86_64);
+
+    // The operating systems below are known to be incompatible with MCJIT as
+    // they are copied from the test/ExecutionEngine/MCJIT/lit.local.cfg and
+    // should be kept in sync.
+    UnsupportedOSs.push_back(Triple::Cygwin);
+    UnsupportedOSs.push_back(Triple::Darwin);
+  }
+
+  /// Returns true if the host architecture is known to support MCJIT
+  bool ArchSupportsMCJIT() {
+    Triple Host(HostTriple);
+    if (std::find(SupportedArchs.begin(), SupportedArchs.end(), Host.getArch())
+        == SupportedArchs.end()) {
+      return false;
+    }
+    return true;
+  }
+
+  /// Returns true if the host OS is known to support MCJIT
+  bool OSSupportsMCJIT() {
+    Triple Host(HostTriple);
+    if (std::find(UnsupportedOSs.begin(), UnsupportedOSs.end(), Host.getOS())
+        == UnsupportedOSs.end()) {
+      return true;
+    }
+    return false;
+  }
+
+  Module *createEmptyModule(StringRef Name) {
+    Module * M = new Module(Name, Context);
+    M->setTargetTriple(Triple::normalize(HostTriple));
+    return M;
+  }
+
+  template<typename FuncType>
+  Function *startFunction(Module *M, StringRef Name) {
+    Function *Result = Function::Create(
+      TypeBuilder<FuncType, false>::get(Context),
+      GlobalValue::ExternalLinkage, Name, M);
+
+    BasicBlock *BB = BasicBlock::Create(Context, Name, Result);
+    Builder.SetInsertPoint(BB);
+
+    return Result;
+  }
+
+  void endFunctionWithRet(Function *Func, Value *RetValue) {
+    Builder.CreateRet(RetValue);
+  }
+
+  // Inserts a simple function that invokes Callee and takes the same arguments:
+  //    int Caller(...) { return Callee(...); }
+  template<typename Signature>
+  Function *insertSimpleCallFunction(Module *M, Function *Callee) {
+    Function *Result = startFunction<Signature>(M, "caller");
+
+    SmallVector<Value*, 1> CallArgs;
+
+    Function::arg_iterator arg_iter = Result->arg_begin();
+    for(;arg_iter != Result->arg_end(); ++arg_iter)
+      CallArgs.push_back(arg_iter);
+
+    Value *ReturnCode = Builder.CreateCall(Callee, CallArgs);
+    Builder.CreateRet(ReturnCode);
+    return Result;
+  }
+
+  // Inserts a function named 'main' that returns a uint32_t:
+  //    int32_t main() { return X; }
+  // where X is given by returnCode
+  Function *insertMainFunction(Module *M, uint32_t returnCode) {
+    Function *Result = startFunction<int32_t(void)>(M, "main");
+
+    Value *ReturnVal = ConstantInt::get(Context, APInt(32, returnCode));
+    endFunctionWithRet(Result, ReturnVal);
+
+    return Result;
+  }
+
+  // Inserts a function
+  //    int32_t add(int32_t a, int32_t b) { return a + b; }
+  // in the current module and returns a pointer to it.
+  Function *insertAddFunction(Module *M, StringRef Name = "add") {
+    Function *Result = startFunction<int32_t(int32_t, int32_t)>(M, Name);
+
+    Function::arg_iterator args = Result->arg_begin();
+    Value *Arg1 = args;
+    Value *Arg2 = ++args;
+    Value *AddResult = Builder.CreateAdd(Arg1, Arg2);
+
+    endFunctionWithRet(Result, AddResult);
+
+    return Result;
+  }
+
+  // Inserts an declaration to a function defined elsewhere
+  Function *insertExternalReferenceToFunction(Module *M, StringRef Name,
+                                              FunctionType *FuncTy) {
+    Function *Result = Function::Create(FuncTy,
+                                        GlobalValue::ExternalLinkage,
+                                        Name, M);
+    return Result;
+  }
+
+  // Inserts an declaration to a function defined elsewhere
+  Function *insertExternalReferenceToFunction(Module *M, Function *Func) {
+    Function *Result = Function::Create(Func->getFunctionType(),
+                                        GlobalValue::AvailableExternallyLinkage,
+                                        Func->getName(), M);
+    return Result;
+  }
+
+  // Inserts a global variable of type int32
+  GlobalVariable *insertGlobalInt32(Module *M,
+                                    StringRef name,
+                                    int32_t InitialValue) {
+    Type *GlobalTy = TypeBuilder<types::i<32>, true>::get(Context);
+    Constant *IV = ConstantInt::get(Context, APInt(32, InitialValue));
+    GlobalVariable *Global = new GlobalVariable(*M,
+                                                GlobalTy,
+                                                false,
+                                                GlobalValue::ExternalLinkage,
+                                                IV,
+                                                name);
+    return Global;
+  }
+
+  void createJIT(Module *M) {
+
+    // Due to the EngineBuilder constructor, it is required to have a Module
+    // in order to construct an ExecutionEngine (i.e. MCJIT)
+    assert(M != 0 && "a non-null Module must be provided to create MCJIT");
+
+    EngineBuilder EB(M);
+    std::string Error;
+    TheJIT.reset(EB.setEngineKind(EngineKind::JIT)
+                 .setUseMCJIT(true) /* can this be folded into the EngineKind enum? */
+                 .setJITMemoryManager(MM)
+                 .setErrorStr(&Error)
+                 .setOptLevel(CodeGenOpt::None)
+                 .setAllocateGVsWithCode(false) /*does this do anything?*/
+                 .setCodeModel(CodeModel::JITDefault)
+                 .setRelocationModel(Reloc::Default)
+                 .setMArch(MArch)
+                 .setMCPU(sys::getHostCPUName())
+                 //.setMAttrs(MAttrs)
+                 .create());
+    // At this point, we cannot modify the module any more.
+    assert(TheJIT.get() != NULL && "error creating MCJIT with EngineBuilder");
+  }
+
+  LLVMContext Context;
+  CodeGenOpt::Level OptLevel;
+  Reloc::Model RelocModel;
+  CodeModel::Model CodeModel;
+  StringRef MArch;
+  SmallVector<std::string, 1> MAttrs;
+  OwningPtr<TargetMachine> TM;
+  OwningPtr<ExecutionEngine> TheJIT;
+  IRBuilder<> Builder;
+  JITMemoryManager *MM;
+
+  std::string HostTriple;
+  SmallVector<Triple::ArchType, 4> SupportedArchs;
+  SmallVector<Triple::OSType, 4> UnsupportedOSs;
+
+  OwningPtr<Module> M;
+};
+
+} // namespace llvm
+
+#endif // MCJIT_TEST_H

llvm/unittests/ExecutionEngine/MCJIT/MCJITTests.def

@@ -0,0 +1 @@
+EXPORTS

llvm/unittests/ExecutionEngine/MCJIT/Makefile

@@ -0,0 +1,18 @@
+##===- unittests/ExecutionEngine/MCJIT/Makefile ------------*- Makefile -*-===##
+#
+#                     The LLVM Compiler Infrastructure
+#
+# This file is distributed under the University of Illinois Open Source
+# License. See LICENSE.TXT for details.
+#
+##===----------------------------------------------------------------------===##
+
+LEVEL = ../../..
+TESTNAME = MCJIT
+LINK_COMPONENTS := core jit mcjit native support
+
+include $(LEVEL)/Makefile.config
+include $(LLVM_SRC_ROOT)/unittests/Makefile.unittest
+
+# Permit these tests to use the MCJIT's symbolic lookup.
+LD.Flags += $(RDYNAMIC)

llvm/unittests/ExecutionEngine/MCJIT/SectionMemoryManager.cpp

@@ -0,0 +1,135 @@
+//===-- SectionMemoryManager.cpp - The memory manager for MCJIT -----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the implementation of the section-based memory manager
+// used by MCJIT.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Config/config.h"
+#include "llvm/Support/DynamicLibrary.h"
+
+#include "SectionMemoryManager.h"
+
+#ifdef __linux__
+// These includes used by SectionMemoryManager::getPointerToNamedFunction()
+// for Glibc trickery. Look comments in this function for more information.
+#ifdef HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+#include <fcntl.h>
+#include <unistd.h>
+#endif
+
+namespace llvm {
+
+uint8_t *SectionMemoryManager::allocateDataSection(uintptr_t Size,
+                                                    unsigned Alignment,
+                                                    unsigned SectionID) {
+  if (!Alignment)
+    Alignment = 16;
+  uint8_t *Addr = (uint8_t*)calloc((Size + Alignment - 1)/Alignment, Alignment);
+  AllocatedDataMem.push_back(sys::MemoryBlock(Addr, Size));
+  return Addr;
+}
+
+uint8_t *SectionMemoryManager::allocateCodeSection(uintptr_t Size,
+                                                    unsigned Alignment,
+                                                    unsigned SectionID) {
+  if (!Alignment)
+    Alignment = 16;
+  unsigned NeedAllocate = Alignment * ((Size + Alignment - 1)/Alignment + 1);
+  uintptr_t Addr = 0;
+  // Look in the list of free code memory regions and use a block there if one
+  // is available.
+  for (int i = 0, e = FreeCodeMem.size(); i != e; ++i) {
+    sys::MemoryBlock &MB = FreeCodeMem[i];
+    if (MB.size() >= NeedAllocate) {
+      Addr = (uintptr_t)MB.base();
+      uintptr_t EndOfBlock = Addr + MB.size();
+      // Align the address.
+      Addr = (Addr + Alignment - 1) & ~(uintptr_t)(Alignment - 1);
+      // Store cutted free memory block.
+      FreeCodeMem[i] = sys::MemoryBlock((void*)(Addr + Size),
+                                        EndOfBlock - Addr - Size);
+      return (uint8_t*)Addr;
+    }
+  }
+
+  // No pre-allocated free block was large enough. Allocate a new memory region.
+  sys::MemoryBlock MB = sys::Memory::AllocateRWX(NeedAllocate, 0, 0);
+
+  AllocatedCodeMem.push_back(MB);
+  Addr = (uintptr_t)MB.base();
+  uintptr_t EndOfBlock = Addr + MB.size();
+  // Align the address.
+  Addr = (Addr + Alignment - 1) & ~(uintptr_t)(Alignment - 1);
+  // The AllocateRWX may allocate much more memory than we need. In this case,
+  // we store the unused memory as a free memory block.
+  unsigned FreeSize = EndOfBlock-Addr-Size;
+  if (FreeSize > 16)
+    FreeCodeMem.push_back(sys::MemoryBlock((void*)(Addr + Size), FreeSize));
+
+  // Return aligned address
+  return (uint8_t*)Addr;
+}
+
+void SectionMemoryManager::invalidateInstructionCache() {
+  for (int i = 0, e = AllocatedCodeMem.size(); i != e; ++i)
+    sys::Memory::InvalidateInstructionCache(AllocatedCodeMem[i].base(),
+                                            AllocatedCodeMem[i].size());
+}
+
+void *SectionMemoryManager::getPointerToNamedFunction(const std::string &Name,
+                                                       bool AbortOnFailure) {
+#if defined(__linux__)
+  //===--------------------------------------------------------------------===//
+  // Function stubs that are invoked instead of certain library calls
+  //
+  // Force the following functions to be linked in to anything that uses the
+  // JIT. This is a hack designed to work around the all-too-clever Glibc
+  // strategy of making these functions work differently when inlined vs. when
+  // not inlined, and hiding their real definitions in a separate archive file
+  // that the dynamic linker can't see. For more info, search for
+  // 'libc_nonshared.a' on Google, or read http://llvm.org/PR274.
+  if (Name == "stat") return (void*)(intptr_t)&stat;
+  if (Name == "fstat") return (void*)(intptr_t)&fstat;
+  if (Name == "lstat") return (void*)(intptr_t)&lstat;
+  if (Name == "stat64") return (void*)(intptr_t)&stat64;
+  if (Name == "fstat64") return (void*)(intptr_t)&fstat64;
+  if (Name == "lstat64") return (void*)(intptr_t)&lstat64;
+  if (Name == "atexit") return (void*)(intptr_t)&atexit;
+  if (Name == "mknod") return (void*)(intptr_t)&mknod;
+#endif // __linux__
+
+  const char *NameStr = Name.c_str();
+  void *Ptr = sys::DynamicLibrary::SearchForAddressOfSymbol(NameStr);
+  if (Ptr) return Ptr;
+
+  // If it wasn't found and if it starts with an underscore ('_') character,
+  // try again without the underscore.
+  if (NameStr[0] == '_') {
+    Ptr = sys::DynamicLibrary::SearchForAddressOfSymbol(NameStr+1);
+    if (Ptr) return Ptr;
+  }
+
+  if (AbortOnFailure)
+    report_fatal_error("Program used external function '" + Name +
+                      "' which could not be resolved!");
+  return 0;
+}
+
+SectionMemoryManager::~SectionMemoryManager() {
+  for (unsigned i = 0, e = AllocatedCodeMem.size(); i != e; ++i)
+    sys::Memory::ReleaseRWX(AllocatedCodeMem[i]);
+  for (unsigned i = 0, e = AllocatedDataMem.size(); i != e; ++i)
+    free(AllocatedDataMem[i].base());
+}
+
+} // namespace llvm

llvm/unittests/ExecutionEngine/MCJIT/SectionMemoryManager.h

@@ -0,0 +1,117 @@
+//===-- SectionMemoryManager.h - Memory allocator for MCJIT -----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the declaration of a section-based memory manager used by
+// the MCJIT execution engine.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_EXECUTION_ENGINE_SECTION_MEMORY_MANAGER_H
+#define LLVM_EXECUTION_ENGINE_SECTION_MEMORY_MANAGER_H
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ExecutionEngine/JITMemoryManager.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/Memory.h"
+
+namespace llvm {
+
+// Section-based memory manager for MCJIT
+class SectionMemoryManager : public JITMemoryManager {
+
+public:
+
+  SectionMemoryManager() { }
+  ~SectionMemoryManager();
+
+  virtual uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
+                                       unsigned SectionID);
+
+  virtual uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment,
+                                       unsigned SectionID);
+
+  virtual void *getPointerToNamedFunction(const std::string &Name,
+                                          bool AbortOnFailure = true);
+
+  // Invalidate instruction cache for code sections. Some platforms with
+  // separate data cache and instruction cache require explicit cache flush,
+  // otherwise JIT code manipulations (like resolved relocations) will get to
+  // the data cache but not to the instruction cache.
+  virtual void invalidateInstructionCache();
+
+private:
+
+  SmallVector<sys::MemoryBlock, 16> AllocatedDataMem;
+  SmallVector<sys::MemoryBlock, 16> AllocatedCodeMem;
+  SmallVector<sys::MemoryBlock, 16> FreeCodeMem;
+
+public:
+  ///
+  /// Functions below are not used by MCJIT, but must be implemented because
+  /// they are declared as pure virtuals in the base class.
+  ///
+
+  virtual void setMemoryWritable() {
+    llvm_unreachable("Unexpected call!");
+  }
+  virtual void setMemoryExecutable() {
+    llvm_unreachable("Unexpected call!");
+  }
+  virtual void setPoisonMemory(bool poison) {
+    llvm_unreachable("Unexpected call!");
+  }
+  virtual void AllocateGOT() {
+    llvm_unreachable("Unexpected call!");
+  }
+  virtual uint8_t *getGOTBase() const {
+    llvm_unreachable("Unexpected call!");
+    return 0;
+  }
+  virtual uint8_t *startFunctionBody(const Function *F,
+                                     uintptr_t &ActualSize){
+    llvm_unreachable("Unexpected call!");
+    return 0;
+  }
+  virtual uint8_t *allocateStub(const GlobalValue* F, unsigned StubSize,
+                                unsigned Alignment) {
+    llvm_unreachable("Unexpected call!");
+    return 0;
+  }
+  virtual void endFunctionBody(const Function *F, uint8_t *FunctionStart,
+                               uint8_t *FunctionEnd) {
+    llvm_unreachable("Unexpected call!");
+  }
+  virtual uint8_t *allocateSpace(intptr_t Size, unsigned Alignment) {
+    llvm_unreachable("Unexpected call!");
+    return 0;
+  }
+  virtual uint8_t *allocateGlobal(uintptr_t Size, unsigned Alignment) {
+    llvm_unreachable("Unexpected call!");
+    return 0;
+  }
+  virtual void deallocateFunctionBody(void *Body) {
+    llvm_unreachable("Unexpected call!");
+  }
+  virtual uint8_t *startExceptionTable(const Function *F,
+                                       uintptr_t &ActualSize) {
+    llvm_unreachable("Unexpected call!");
+    return 0;
+  }
+  virtual void endExceptionTable(const Function *F, uint8_t *TableStart,
+                                 uint8_t *TableEnd, uint8_t *FrameRegister) {
+    llvm_unreachable("Unexpected call!");
+  }
+  virtual void deallocateExceptionTable(void *ET) {
+    llvm_unreachable("Unexpected call!");
+  }
+};
+
+}
+
+#endif // LLVM_EXECUTION_ENGINE_SECTION_MEMORY_MANAGER_H

llvm/unittests/ExecutionEngine/Makefile

@@ -10,7 +10,7 @@
 LEVEL = ../..
 TESTNAME = ExecutionEngine
 LINK_COMPONENTS :=interpreter
-PARALLEL_DIRS = JIT
+PARALLEL_DIRS = JIT MCJIT
 
 include $(LEVEL)/Makefile.config
 include $(LLVM_SRC_ROOT)/unittests/Makefile.unittest

llvm/unittests/Support/CMakeLists.txt

@@ -17,6 +17,7 @@ add_llvm_unittest(SupportTests
   LeakDetectorTest.cpp
   ManagedStatic.cpp
   MathExtrasTest.cpp
+  MemoryBufferTest.cpp
   MemoryTest.cpp
   Path.cpp
   RegexTest.cpp

llvm/unittests/Support/MemoryBufferTest.cpp

@@ -0,0 +1,99 @@
+//===- llvm/unittest/Support/MemoryBufferTest.cpp - MemoryBuffer tests ----===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements unit tests for the MemoryBuffer support class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/ADT/OwningPtr.h"
+
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+class MemoryBufferTest : public testing::Test {
+protected:
+  MemoryBufferTest()
+  : data("this is some data")
+  { }
+
+  virtual void SetUp() { }
+
+  typedef OwningPtr<MemoryBuffer> OwningBuffer;
+
+  std::string data;
+};
+
+namespace {
+
+TEST_F(MemoryBufferTest, get) {
+  // Default name and null-terminator flag
+  OwningBuffer MB1(MemoryBuffer::getMemBuffer(data));
+  EXPECT_TRUE(0 != MB1.get());
+
+  // RequiresNullTerminator = false
+  OwningBuffer MB2(MemoryBuffer::getMemBuffer(data, "one", false));
+  EXPECT_TRUE(0 != MB2.get());
+
+  // RequiresNullTerminator = true
+  OwningBuffer MB3(MemoryBuffer::getMemBuffer(data, "two", true));
+  EXPECT_TRUE(0 != MB3.get());
+
+  // verify all 3 buffers point to the same address
+  EXPECT_EQ(MB1->getBufferStart(), MB2->getBufferStart());
+  EXPECT_EQ(MB2->getBufferStart(), MB3->getBufferStart());
+
+  // verify the original data is unmodified after deleting the buffers
+  MB1.reset();
+  MB2.reset();
+  MB3.reset();
+  EXPECT_EQ("this is some data", data);
+}
+
+TEST_F(MemoryBufferTest, copy) {
+  // copy with no name
+  OwningBuffer MBC1(MemoryBuffer::getMemBufferCopy(data));
+  EXPECT_TRUE(0 != MBC1.get());
+
+  // copy with a name
+  OwningBuffer MBC2(MemoryBuffer::getMemBufferCopy(data, "copy"));
+  EXPECT_TRUE(0 != MBC2.get());
+
+  // verify the two copies do not point to the same place
+  EXPECT_NE(MBC1->getBufferStart(), MBC2->getBufferStart());
+}
+
+TEST_F(MemoryBufferTest, make_new) {
+  // 0-sized buffer
+  OwningBuffer Zero(MemoryBuffer::getNewUninitMemBuffer(0));
+  EXPECT_TRUE(0 != Zero.get());
+
+  // uninitialized buffer with no name
+  OwningBuffer One(MemoryBuffer::getNewUninitMemBuffer(321));
+  EXPECT_TRUE(0 != One.get());
+
+  // uninitialized buffer with name
+  OwningBuffer Two(MemoryBuffer::getNewUninitMemBuffer(123, "bla"));
+  EXPECT_TRUE(0 != Two.get());
+
+  // 0-initialized buffer with no name
+  OwningBuffer Three(MemoryBuffer::getNewMemBuffer(321, data));
+  EXPECT_TRUE(0 != Three.get());
+  for (size_t i = 0; i < 321; ++i)
+    EXPECT_EQ(0, Three->getBufferStart()[0]);
+
+  // 0-initialized buffer with name
+  OwningBuffer Four(MemoryBuffer::getNewMemBuffer(123, "zeros"));
+  EXPECT_TRUE(0 != Four.get());
+  for (size_t i = 0; i < 123; ++i)
+    EXPECT_EQ(0, Four->getBufferStart()[0]);
+}
+
+}