Import LLVM, at r72732.

1 files changed, 1615 insertions, 0 deletions

diff --git a/lib/ExecutionEngine/JIT/JITEmitter.cpp b/lib/ExecutionEngine/JIT/JITEmitter.cpp
new file mode 100644
index 0000000..d3b0820
--- /dev/null
+++ b/lib/ExecutionEngine/JIT/JITEmitter.cpp
@@ -0,0 +1,1615 @@
+//===-- JITEmitter.cpp - Write machine code to executable memory ----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines a MachineCodeEmitter object that is used by the JIT to
+// write machine code to memory and remember where relocatable values are.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "jit"
+#include "JIT.h"
+#include "JITDwarfEmitter.h"
+#include "llvm/Constants.h"
+#include "llvm/Module.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/CodeGen/JITCodeEmitter.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineConstantPool.h"
+#include "llvm/CodeGen/MachineJumpTableInfo.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/CodeGen/MachineRelocation.h"
+#include "llvm/ExecutionEngine/JITMemoryManager.h"
+#include "llvm/ExecutionEngine/GenericValue.h"
+#include "llvm/CodeGen/MachineCodeInfo.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetJITInfo.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetOptions.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/MutexGuard.h"
+#include "llvm/Support/ValueHandle.h"
+#include "llvm/System/Disassembler.h"
+#include "llvm/System/Memory.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
+#include <algorithm>
+#ifndef NDEBUG
+#include <iomanip>
+#endif
+using namespace llvm;
+
+STATISTIC(NumBytes, "Number of bytes of machine code compiled");
+STATISTIC(NumRelos, "Number of relocations applied");
+static JIT *TheJIT = 0;
+
+
+//===----------------------------------------------------------------------===//
+// JIT lazy compilation code.
+//
+namespace {
+  class JITResolverState {
+  public:
+    typedef std::map<AssertingVH<Function>, void*> FunctionToStubMapTy;
+    typedef std::map<void*, Function*> StubToFunctionMapTy;
+    typedef std::map<AssertingVH<GlobalValue>, void*> GlobalToIndirectSymMapTy;
+  private:
+    /// FunctionToStubMap - Keep track of the stub created for a particular
+    /// function so that we can reuse them if necessary.
+    FunctionToStubMapTy FunctionToStubMap;
+
+    /// StubToFunctionMap - Keep track of the function that each stub
+    /// corresponds to.
+    StubToFunctionMapTy StubToFunctionMap;
+
+    /// GlobalToIndirectSymMap - Keep track of the indirect symbol created for a
+    /// particular GlobalVariable so that we can reuse them if necessary.
+    GlobalToIndirectSymMapTy GlobalToIndirectSymMap;
+
+  public:
+    FunctionToStubMapTy& getFunctionToStubMap(const MutexGuard& locked) {
+      assert(locked.holds(TheJIT->lock));
+      return FunctionToStubMap;
+    }
+
+    StubToFunctionMapTy& getStubToFunctionMap(const MutexGuard& locked) {
+      assert(locked.holds(TheJIT->lock));
+      return StubToFunctionMap;
+    }
+
+    GlobalToIndirectSymMapTy& getGlobalToIndirectSymMap(const MutexGuard& locked) {
+      assert(locked.holds(TheJIT->lock));
+      return GlobalToIndirectSymMap;
+    }
+  };
+
+  /// JITResolver - Keep track of, and resolve, call sites for functions that
+  /// have not yet been compiled.
+  class JITResolver {
+    typedef JITResolverState::FunctionToStubMapTy FunctionToStubMapTy;
+    typedef JITResolverState::StubToFunctionMapTy StubToFunctionMapTy;
+    typedef JITResolverState::GlobalToIndirectSymMapTy GlobalToIndirectSymMapTy;
+
+    /// LazyResolverFn - The target lazy resolver function that we actually
+    /// rewrite instructions to use.
+    TargetJITInfo::LazyResolverFn LazyResolverFn;
+
+    JITResolverState state;
+
+    /// ExternalFnToStubMap - This is the equivalent of FunctionToStubMap for
+    /// external functions.
+    std::map<void*, void*> ExternalFnToStubMap;
+
+    /// revGOTMap - map addresses to indexes in the GOT
+    std::map<void*, unsigned> revGOTMap;
+    unsigned nextGOTIndex;
+
+    static JITResolver *TheJITResolver;
+  public:
+    explicit JITResolver(JIT &jit) : nextGOTIndex(0) {
+      TheJIT = &jit;
+
+      LazyResolverFn = jit.getJITInfo().getLazyResolverFunction(JITCompilerFn);
+      assert(TheJITResolver == 0 && "Multiple JIT resolvers?");
+      TheJITResolver = this;
+    }
+    
+    ~JITResolver() {
+      TheJITResolver = 0;
+    }
+
+    /// getFunctionStubIfAvailable - This returns a pointer to a function stub
+    /// if it has already been created.
+    void *getFunctionStubIfAvailable(Function *F);
+
+    /// getFunctionStub - This returns a pointer to a function stub, creating
+    /// one on demand as needed.  If empty is true, create a function stub
+    /// pointing at address 0, to be filled in later.
+    void *getFunctionStub(Function *F);
+
+    /// getExternalFunctionStub - Return a stub for the function at the
+    /// specified address, created lazily on demand.
+    void *getExternalFunctionStub(void *FnAddr);
+
+    /// getGlobalValueIndirectSym - Return an indirect symbol containing the
+    /// specified GV address.
+    void *getGlobalValueIndirectSym(GlobalValue *V, void *GVAddress);
+
+    /// AddCallbackAtLocation - If the target is capable of rewriting an
+    /// instruction without the use of a stub, record the location of the use so
+    /// we know which function is being used at the location.
+    void *AddCallbackAtLocation(Function *F, void *Location) {
+      MutexGuard locked(TheJIT->lock);
+      /// Get the target-specific JIT resolver function.
+      state.getStubToFunctionMap(locked)[Location] = F;
+      return (void*)(intptr_t)LazyResolverFn;
+    }
+    
+    void getRelocatableGVs(SmallVectorImpl<GlobalValue*> &GVs,
+                           SmallVectorImpl<void*> &Ptrs);
+    
+    GlobalValue *invalidateStub(void *Stub);
+
+    /// getGOTIndexForAddress - Return a new or existing index in the GOT for
+    /// an address.  This function only manages slots, it does not manage the
+    /// contents of the slots or the memory associated with the GOT.
+    unsigned getGOTIndexForAddr(void *addr);
+
+    /// JITCompilerFn - This function is called to resolve a stub to a compiled
+    /// address.  If the LLVM Function corresponding to the stub has not yet
+    /// been compiled, this function compiles it first.
+    static void *JITCompilerFn(void *Stub);
+  };
+}
+
+JITResolver *JITResolver::TheJITResolver = 0;
+
+/// getFunctionStubIfAvailable - This returns a pointer to a function stub
+/// if it has already been created.
+void *JITResolver::getFunctionStubIfAvailable(Function *F) {
+  MutexGuard locked(TheJIT->lock);
+
+  // If we already have a stub for this function, recycle it.
+  void *&Stub = state.getFunctionToStubMap(locked)[F];
+  return Stub;
+}
+
+/// getFunctionStub - This returns a pointer to a function stub, creating
+/// one on demand as needed.
+void *JITResolver::getFunctionStub(Function *F) {
+  MutexGuard locked(TheJIT->lock);
+
+  // If we already have a stub for this function, recycle it.
+  void *&Stub = state.getFunctionToStubMap(locked)[F];
+  if (Stub) return Stub;
+
+  // Call the lazy resolver function unless we are JIT'ing non-lazily, in which
+  // case we must resolve the symbol now.
+  void *Actual =  TheJIT->isLazyCompilationDisabled() 
+    ? (void *)0 : (void *)(intptr_t)LazyResolverFn;
+   
+  // If this is an external declaration, attempt to resolve the address now
+  // to place in the stub.
+  if (F->isDeclaration() && !F->hasNotBeenReadFromBitcode()) {
+    Actual = TheJIT->getPointerToFunction(F);
+
+    // If we resolved the symbol to a null address (eg. a weak external)
+    // don't emit a stub. Return a null pointer to the application.  If dlsym
+    // stubs are enabled, not being able to resolve the address is not
+    // meaningful.
+    if (!Actual && !TheJIT->areDlsymStubsEnabled()) return 0;
+  }
+
+  // Codegen a new stub, calling the lazy resolver or the actual address of the
+  // external function, if it was resolved.
+  Stub = TheJIT->getJITInfo().emitFunctionStub(F, Actual,
+                                               *TheJIT->getCodeEmitter());
+
+  if (Actual != (void*)(intptr_t)LazyResolverFn) {
+    // If we are getting the stub for an external function, we really want the
+    // address of the stub in the GlobalAddressMap for the JIT, not the address
+    // of the external function.
+    TheJIT->updateGlobalMapping(F, Stub);
+  }
+
+  DOUT << "JIT: Stub emitted at [" << Stub << "] for function '"
+       << F->getName() << "'\n";
+
+  // Finally, keep track of the stub-to-Function mapping so that the
+  // JITCompilerFn knows which function to compile!
+  state.getStubToFunctionMap(locked)[Stub] = F;
+  
+  // If we are JIT'ing non-lazily but need to call a function that does not
+  // exist yet, add it to the JIT's work list so that we can fill in the stub
+  // address later.
+  if (!Actual && TheJIT->isLazyCompilationDisabled())
+    if (!F->isDeclaration() || F->hasNotBeenReadFromBitcode())
+      TheJIT->addPendingFunction(F);
+  
+  return Stub;
+}
+
+/// getGlobalValueIndirectSym - Return a lazy pointer containing the specified
+/// GV address.
+void *JITResolver::getGlobalValueIndirectSym(GlobalValue *GV, void *GVAddress) {
+  MutexGuard locked(TheJIT->lock);
+
+  // If we already have a stub for this global variable, recycle it.
+  void *&IndirectSym = state.getGlobalToIndirectSymMap(locked)[GV];
+  if (IndirectSym) return IndirectSym;
+
+  // Otherwise, codegen a new indirect symbol.
+  IndirectSym = TheJIT->getJITInfo().emitGlobalValueIndirectSym(GV, GVAddress,
+                                                     *TheJIT->getCodeEmitter());
+
+  DOUT << "JIT: Indirect symbol emitted at [" << IndirectSym << "] for GV '"
+       << GV->getName() << "'\n";
+
+  return IndirectSym;
+}
+
+/// getExternalFunctionStub - Return a stub for the function at the
+/// specified address, created lazily on demand.
+void *JITResolver::getExternalFunctionStub(void *FnAddr) {
+  // If we already have a stub for this function, recycle it.
+  void *&Stub = ExternalFnToStubMap[FnAddr];
+  if (Stub) return Stub;
+
+  Stub = TheJIT->getJITInfo().emitFunctionStub(0, FnAddr,
+                                               *TheJIT->getCodeEmitter());
+
+  DOUT << "JIT: Stub emitted at [" << Stub
+       << "] for external function at '" << FnAddr << "'\n";
+  return Stub;
+}
+
+unsigned JITResolver::getGOTIndexForAddr(void* addr) {
+  unsigned idx = revGOTMap[addr];
+  if (!idx) {
+    idx = ++nextGOTIndex;
+    revGOTMap[addr] = idx;
+    DOUT << "JIT: Adding GOT entry " << idx << " for addr [" << addr << "]\n";
+  }
+  return idx;
+}
+
+void JITResolver::getRelocatableGVs(SmallVectorImpl<GlobalValue*> &GVs,
+                                    SmallVectorImpl<void*> &Ptrs) {
+  MutexGuard locked(TheJIT->lock);
+  
+  FunctionToStubMapTy &FM = state.getFunctionToStubMap(locked);
+  GlobalToIndirectSymMapTy &GM = state.getGlobalToIndirectSymMap(locked);
+  
+  for (FunctionToStubMapTy::iterator i = FM.begin(), e = FM.end(); i != e; ++i){
+    Function *F = i->first;
+    if (F->isDeclaration() && F->hasExternalLinkage()) {
+      GVs.push_back(i->first);
+      Ptrs.push_back(i->second);
+    }
+  }
+  for (GlobalToIndirectSymMapTy::iterator i = GM.begin(), e = GM.end();
+       i != e; ++i) {
+    GVs.push_back(i->first);
+    Ptrs.push_back(i->second);
+  }
+}
+
+GlobalValue *JITResolver::invalidateStub(void *Stub) {
+  MutexGuard locked(TheJIT->lock);
+  
+  FunctionToStubMapTy &FM = state.getFunctionToStubMap(locked);
+  StubToFunctionMapTy &SM = state.getStubToFunctionMap(locked);
+  GlobalToIndirectSymMapTy &GM = state.getGlobalToIndirectSymMap(locked);
+  
+  // Look up the cheap way first, to see if it's a function stub we are
+  // invalidating.  If so, remove it from both the forward and reverse maps.
+  if (SM.find(Stub) != SM.end()) {
+    Function *F = SM[Stub];
+    SM.erase(Stub);
+    FM.erase(F);
+    return F;
+  }
+  
+  // Otherwise, it might be an indirect symbol stub.  Find it and remove it.
+  for (GlobalToIndirectSymMapTy::iterator i = GM.begin(), e = GM.end();
+       i != e; ++i) {
+    if (i->second != Stub)
+      continue;
+    GlobalValue *GV = i->first;
+    GM.erase(i);
+    return GV;
+  }
+  
+  // Lastly, check to see if it's in the ExternalFnToStubMap.
+  for (std::map<void *, void *>::iterator i = ExternalFnToStubMap.begin(),
+       e = ExternalFnToStubMap.end(); i != e; ++i) {
+    if (i->second != Stub)
+      continue;
+    ExternalFnToStubMap.erase(i);
+    break;
+  }
+  
+  return 0;
+}
+
+/// JITCompilerFn - This function is called when a lazy compilation stub has
+/// been entered.  It looks up which function this stub corresponds to, compiles
+/// it if necessary, then returns the resultant function pointer.
+void *JITResolver::JITCompilerFn(void *Stub) {
+  JITResolver &JR = *TheJITResolver;
+  
+  Function* F = 0;
+  void* ActualPtr = 0;
+
+  {
+    // Only lock for getting the Function. The call getPointerToFunction made
+    // in this function might trigger function materializing, which requires
+    // JIT lock to be unlocked.
+    MutexGuard locked(TheJIT->lock);
+
+    // The address given to us for the stub may not be exactly right, it might be
+    // a little bit after the stub.  As such, use upper_bound to find it.
+    StubToFunctionMapTy::iterator I =
+      JR.state.getStubToFunctionMap(locked).upper_bound(Stub);
+    assert(I != JR.state.getStubToFunctionMap(locked).begin() &&
+           "This is not a known stub!");
+    F = (--I)->second;
+    ActualPtr = I->first;
+  }
+
+  // If we have already code generated the function, just return the address.
+  void *Result = TheJIT->getPointerToGlobalIfAvailable(F);
+  
+  if (!Result) {
+    // Otherwise we don't have it, do lazy compilation now.
+    
+    // If lazy compilation is disabled, emit a useful error message and abort.
+    if (TheJIT->isLazyCompilationDisabled()) {
+      cerr << "LLVM JIT requested to do lazy compilation of function '"
+      << F->getName() << "' when lazy compiles are disabled!\n";
+      abort();
+    }
+  
+    // We might like to remove the stub from the StubToFunction map.
+    // We can't do that! Multiple threads could be stuck, waiting to acquire the
+    // lock above. As soon as the 1st function finishes compiling the function,
+    // the next one will be released, and needs to be able to find the function
+    // it needs to call.
+    //JR.state.getStubToFunctionMap(locked).erase(I);
+
+    DOUT << "JIT: Lazily resolving function '" << F->getName()
+         << "' In stub ptr = " << Stub << " actual ptr = "
+         << ActualPtr << "\n";
+
+    Result = TheJIT->getPointerToFunction(F);
+  }
+  
+  // Reacquire the lock to erase the stub in the map.
+  MutexGuard locked(TheJIT->lock);
+
+  // We don't need to reuse this stub in the future, as F is now compiled.
+  JR.state.getFunctionToStubMap(locked).erase(F);
+
+  // FIXME: We could rewrite all references to this stub if we knew them.
+
+  // What we will do is set the compiled function address to map to the
+  // same GOT entry as the stub so that later clients may update the GOT
+  // if they see it still using the stub address.
+  // Note: this is done so the Resolver doesn't have to manage GOT memory
+  // Do this without allocating map space if the target isn't using a GOT
+  if(JR.revGOTMap.find(Stub) != JR.revGOTMap.end())
+    JR.revGOTMap[Result] = JR.revGOTMap[Stub];
+
+  return Result;
+}
+
+//===----------------------------------------------------------------------===//
+// Function Index Support
+
+// On MacOS we generate an index of currently JIT'd functions so that
+// performance tools can determine a symbol name and accurate code range for a
+// PC value.  Because performance tools are generally asynchronous, the code
+// below is written with the hope that it could be interrupted at any time and
+// have useful answers.  However, we don't go crazy with atomic operations, we
+// just do a "reasonable effort".
+#ifdef __APPLE__ 
+#define ENABLE_JIT_SYMBOL_TABLE 0
+#endif
+
+/// JitSymbolEntry - Each function that is JIT compiled results in one of these
+/// being added to an array of symbols.  This indicates the name of the function
+/// as well as the address range it occupies.  This allows the client to map
+/// from a PC value to the name of the function.
+struct JitSymbolEntry {
+  const char *FnName;   // FnName - a strdup'd string.
+  void *FnStart;
+  intptr_t FnSize;
+};
+
+
+struct JitSymbolTable {
+  /// NextPtr - This forms a linked list of JitSymbolTable entries.  This
+  /// pointer is not used right now, but might be used in the future.  Consider
+  /// it reserved for future use.
+  JitSymbolTable *NextPtr;
+  
+  /// Symbols - This is an array of JitSymbolEntry entries.  Only the first
+  /// 'NumSymbols' symbols are valid.
+  JitSymbolEntry *Symbols;
+  
+  /// NumSymbols - This indicates the number entries in the Symbols array that
+  /// are valid.
+  unsigned NumSymbols;
+  
+  /// NumAllocated - This indicates the amount of space we have in the Symbols
+  /// array.  This is a private field that should not be read by external tools.
+  unsigned NumAllocated;
+};
+
+#if ENABLE_JIT_SYMBOL_TABLE 
+JitSymbolTable *__jitSymbolTable;
+#endif
+
+static void AddFunctionToSymbolTable(const char *FnName, 
+                                     void *FnStart, intptr_t FnSize) {
+  assert(FnName != 0 && FnStart != 0 && "Bad symbol to add");
+  JitSymbolTable **SymTabPtrPtr = 0;
+#if !ENABLE_JIT_SYMBOL_TABLE
+  return;
+#else
+  SymTabPtrPtr = &__jitSymbolTable;
+#endif
+  
+  // If this is the first entry in the symbol table, add the JitSymbolTable
+  // index.
+  if (*SymTabPtrPtr == 0) {
+    JitSymbolTable *New = new JitSymbolTable();
+    New->NextPtr = 0;
+    New->Symbols = 0;
+    New->NumSymbols = 0;
+    New->NumAllocated = 0;
+    *SymTabPtrPtr = New;
+  }
+  
+  JitSymbolTable *SymTabPtr = *SymTabPtrPtr;
+  
+  // If we have space in the table, reallocate the table.
+  if (SymTabPtr->NumSymbols >= SymTabPtr->NumAllocated) {
+    // If we don't have space, reallocate the table.
+    unsigned NewSize = std::max(64U, SymTabPtr->NumAllocated*2);
+    JitSymbolEntry *NewSymbols = new JitSymbolEntry[NewSize];
+    JitSymbolEntry *OldSymbols = SymTabPtr->Symbols;
+    
+    // Copy the old entries over.
+    memcpy(NewSymbols, OldSymbols, SymTabPtr->NumSymbols*sizeof(OldSymbols[0]));
+    
+    // Swap the new symbols in, delete the old ones.
+    SymTabPtr->Symbols = NewSymbols;
+    SymTabPtr->NumAllocated = NewSize;
+    delete [] OldSymbols;
+  }
+  
+  // Otherwise, we have enough space, just tack it onto the end of the array.
+  JitSymbolEntry &Entry = SymTabPtr->Symbols[SymTabPtr->NumSymbols];
+  Entry.FnName = strdup(FnName);
+  Entry.FnStart = FnStart;
+  Entry.FnSize = FnSize;
+  ++SymTabPtr->NumSymbols;
+}
+
+static void RemoveFunctionFromSymbolTable(void *FnStart) {
+  assert(FnStart && "Invalid function pointer");
+  JitSymbolTable **SymTabPtrPtr = 0;
+#if !ENABLE_JIT_SYMBOL_TABLE
+  return;
+#else
+  SymTabPtrPtr = &__jitSymbolTable;
+#endif
+  
+  JitSymbolTable *SymTabPtr = *SymTabPtrPtr;
+  JitSymbolEntry *Symbols = SymTabPtr->Symbols;
+  
+  // Scan the table to find its index.  The table is not sorted, so do a linear
+  // scan.
+  unsigned Index;
+  for (Index = 0; Symbols[Index].FnStart != FnStart; ++Index)
+    assert(Index != SymTabPtr->NumSymbols && "Didn't find function!");
+  
+  // Once we have an index, we know to nuke this entry, overwrite it with the
+  // entry at the end of the array, making the last entry redundant.
+  const char *OldName = Symbols[Index].FnName;
+  Symbols[Index] = Symbols[SymTabPtr->NumSymbols-1];
+  free((void*)OldName);
+  
+  // Drop the number of symbols in the table.
+  --SymTabPtr->NumSymbols;
+
+  // Finally, if we deleted the final symbol, deallocate the table itself.
+  if (SymTabPtr->NumSymbols != 0) 
+    return;
+  
+  *SymTabPtrPtr = 0;
+  delete [] Symbols;
+  delete SymTabPtr;
+}
+
+//===----------------------------------------------------------------------===//
+// JITEmitter code.
+//
+namespace {
+  /// JITEmitter - The JIT implementation of the MachineCodeEmitter, which is
+  /// used to output functions to memory for execution.
+  class JITEmitter : public JITCodeEmitter {
+    JITMemoryManager *MemMgr;
+
+    // When outputting a function stub in the context of some other function, we
+    // save BufferBegin/BufferEnd/CurBufferPtr here.
+    uint8_t *SavedBufferBegin, *SavedBufferEnd, *SavedCurBufferPtr;
+
+    /// Relocations - These are the relocations that the function needs, as
+    /// emitted.
+    std::vector<MachineRelocation> Relocations;
+    
+    /// MBBLocations - This vector is a mapping from MBB ID's to their address.
+    /// It is filled in by the StartMachineBasicBlock callback and queried by
+    /// the getMachineBasicBlockAddress callback.
+    std::vector<uintptr_t> MBBLocations;
+
+    /// ConstantPool - The constant pool for the current function.
+    ///
+    MachineConstantPool *ConstantPool;
+
+    /// ConstantPoolBase - A pointer to the first entry in the constant pool.
+    ///
+    void *ConstantPoolBase;
+
+    /// ConstPoolAddresses - Addresses of individual constant pool entries.
+    ///
+    SmallVector<uintptr_t, 8> ConstPoolAddresses;
+
+    /// JumpTable - The jump tables for the current function.
+    ///
+    MachineJumpTableInfo *JumpTable;
+    
+    /// JumpTableBase - A pointer to the first entry in the jump table.
+    ///
+    void *JumpTableBase;
+
+    /// Resolver - This contains info about the currently resolved functions.
+    JITResolver Resolver;
+    
+    /// DE - The dwarf emitter for the jit.
+    JITDwarfEmitter *DE;
+
+    /// LabelLocations - This vector is a mapping from Label ID's to their 
+    /// address.
+    std::vector<uintptr_t> LabelLocations;
+
+    /// MMI - Machine module info for exception informations
+    MachineModuleInfo* MMI;
+
+    // GVSet - a set to keep track of which globals have been seen
+    SmallPtrSet<const GlobalVariable*, 8> GVSet;
+
+    // CurFn - The llvm function being emitted.  Only valid during 
+    // finishFunction().
+    const Function *CurFn;
+    
+    // CurFnStubUses - For a given Function, a vector of stubs that it
+    // references.  This facilitates the JIT detecting that a stub is no
+    // longer used, so that it may be deallocated.
+    DenseMap<const Function *, SmallVector<void*, 1> > CurFnStubUses;
+    
+    // StubFnRefs - For a given pointer to a stub, a set of Functions which
+    // reference the stub.  When the count of a stub's references drops to zero,
+    // the stub is unused.
+    DenseMap<void *, SmallPtrSet<const Function*, 1> > StubFnRefs;
+    
+    // ExtFnStubs - A map of external function names to stubs which have entries
+    // in the JITResolver's ExternalFnToStubMap.
+    StringMap<void *> ExtFnStubs;
+
+    // MCI - A pointer to a MachineCodeInfo object to update with information.
+    MachineCodeInfo *MCI;
+
+  public:
+    JITEmitter(JIT &jit, JITMemoryManager *JMM) : Resolver(jit), CurFn(0), MCI(0) {
+      MemMgr = JMM ? JMM : JITMemoryManager::CreateDefaultMemManager();
+      if (jit.getJITInfo().needsGOT()) {
+        MemMgr->AllocateGOT();
+        DOUT << "JIT is managing a GOT\n";
+      }
+
+      if (ExceptionHandling) DE = new JITDwarfEmitter(jit);
+    }
+    ~JITEmitter() { 
+      delete MemMgr;
+      if (ExceptionHandling) delete DE;
+    }
+
+    /// classof - Methods for support type inquiry through isa, cast, and
+    /// dyn_cast:
+    ///
+    static inline bool classof(const JITEmitter*) { return true; }
+    static inline bool classof(const MachineCodeEmitter*) { return true; }
+    
+    JITResolver &getJITResolver() { return Resolver; }
+
+    virtual void startFunction(MachineFunction &F);
+    virtual bool finishFunction(MachineFunction &F);
+    
+    void emitConstantPool(MachineConstantPool *MCP);
+    void initJumpTableInfo(MachineJumpTableInfo *MJTI);
+    void emitJumpTableInfo(MachineJumpTableInfo *MJTI);
+    
+    virtual void startGVStub(const GlobalValue* GV, unsigned StubSize,
+                                   unsigned Alignment = 1);
+    virtual void startGVStub(const GlobalValue* GV, void *Buffer,
+                             unsigned StubSize);
+    virtual void* finishGVStub(const GlobalValue *GV);
+
+    /// allocateSpace - Reserves space in the current block if any, or
+    /// allocate a new one of the given size.
+    virtual void *allocateSpace(uintptr_t Size, unsigned Alignment);
+
+    virtual void addRelocation(const MachineRelocation &MR) {
+      Relocations.push_back(MR);
+    }
+    
+    virtual void StartMachineBasicBlock(MachineBasicBlock *MBB) {
+      if (MBBLocations.size() <= (unsigned)MBB->getNumber())
+        MBBLocations.resize((MBB->getNumber()+1)*2);
+      MBBLocations[MBB->getNumber()] = getCurrentPCValue();
+      DOUT << "JIT: Emitting BB" << MBB->getNumber() << " at ["
+           << (void*) getCurrentPCValue() << "]\n";
+    }
+
+    virtual uintptr_t getConstantPoolEntryAddress(unsigned Entry) const;
+    virtual uintptr_t getJumpTableEntryAddress(unsigned Entry) const;
+
+    virtual uintptr_t getMachineBasicBlockAddress(MachineBasicBlock *MBB) const {
+      assert(MBBLocations.size() > (unsigned)MBB->getNumber() && 
+             MBBLocations[MBB->getNumber()] && "MBB not emitted!");
+      return MBBLocations[MBB->getNumber()];
+    }
+
+    /// deallocateMemForFunction - Deallocate all memory for the specified
+    /// function body.
+    void deallocateMemForFunction(Function *F);
+
+    /// AddStubToCurrentFunction - Mark the current function being JIT'd as
+    /// using the stub at the specified address. Allows
+    /// deallocateMemForFunction to also remove stubs no longer referenced.
+    void AddStubToCurrentFunction(void *Stub);
+    
+    /// getExternalFnStubs - Accessor for the JIT to find stubs emitted for
+    /// MachineRelocations that reference external functions by name.
+    const StringMap<void*> &getExternalFnStubs() const { return ExtFnStubs; }
+    
+    virtual void emitLabel(uint64_t LabelID) {
+      if (LabelLocations.size() <= LabelID)
+        LabelLocations.resize((LabelID+1)*2);
+      LabelLocations[LabelID] = getCurrentPCValue();
+    }
+
+    virtual uintptr_t getLabelAddress(uint64_t LabelID) const {
+      assert(LabelLocations.size() > (unsigned)LabelID && 
+             LabelLocations[LabelID] && "Label not emitted!");
+      return LabelLocations[LabelID];
+    }
+ 
+    virtual void setModuleInfo(MachineModuleInfo* Info) {
+      MMI = Info;
+      if (ExceptionHandling) DE->setModuleInfo(Info);
+    }
+
+    void setMemoryExecutable(void) {
+      MemMgr->setMemoryExecutable();
+    }
+    
+    JITMemoryManager *getMemMgr(void) const { return MemMgr; }
+
+    void setMachineCodeInfo(MachineCodeInfo *mci) {
+      MCI = mci;
+    }
+
+  private:
+    void *getPointerToGlobal(GlobalValue *GV, void *Reference, bool NoNeedStub);
+    void *getPointerToGVIndirectSym(GlobalValue *V, void *Reference,
+                                    bool NoNeedStub);
+    unsigned addSizeOfGlobal(const GlobalVariable *GV, unsigned Size);
+    unsigned addSizeOfGlobalsInConstantVal(const Constant *C, unsigned Size);
+    unsigned addSizeOfGlobalsInInitializer(const Constant *Init, unsigned Size);
+    unsigned GetSizeOfGlobalsInBytes(MachineFunction &MF);
+  };
+}
+
+void *JITEmitter::getPointerToGlobal(GlobalValue *V, void *Reference,
+                                     bool DoesntNeedStub) {
+  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
+    return TheJIT->getOrEmitGlobalVariable(GV);
+
+  if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V))
+    return TheJIT->getPointerToGlobal(GA->resolveAliasedGlobal(false));
+
+  // If we have already compiled the function, return a pointer to its body.
+  Function *F = cast<Function>(V);
+  void *ResultPtr;
+  if (!DoesntNeedStub && !TheJIT->isLazyCompilationDisabled()) {
+    // Return the function stub if it's already created.
+    ResultPtr = Resolver.getFunctionStubIfAvailable(F);
+    if (ResultPtr)
+      AddStubToCurrentFunction(ResultPtr);
+  } else {
+    ResultPtr = TheJIT->getPointerToGlobalIfAvailable(F);
+  }
+  if (ResultPtr) return ResultPtr;
+
+  // If this is an external function pointer, we can force the JIT to
+  // 'compile' it, which really just adds it to the map.  In dlsym mode, 
+  // external functions are forced through a stub, regardless of reloc type.
+  if (F->isDeclaration() && !F->hasNotBeenReadFromBitcode() &&
+      DoesntNeedStub && !TheJIT->areDlsymStubsEnabled())
+    return TheJIT->getPointerToFunction(F);
+
+  // Okay, the function has not been compiled yet, if the target callback
+  // mechanism is capable of rewriting the instruction directly, prefer to do
+  // that instead of emitting a stub.  This uses the lazy resolver, so is not
+  // legal if lazy compilation is disabled.
+  if (DoesntNeedStub && !TheJIT->isLazyCompilationDisabled())
+    return Resolver.AddCallbackAtLocation(F, Reference);
+
+  // Otherwise, we have to emit a stub.
+  void *StubAddr = Resolver.getFunctionStub(F);
+
+  // Add the stub to the current function's list of referenced stubs, so we can
+  // deallocate them if the current function is ever freed.  It's possible to
+  // return null from getFunctionStub in the case of a weak extern that fails
+  // to resolve.
+  if (StubAddr)
+    AddStubToCurrentFunction(StubAddr);
+
+  return StubAddr;
+}
+
+void *JITEmitter::getPointerToGVIndirectSym(GlobalValue *V, void *Reference,
+                                            bool NoNeedStub) {
+  // Make sure GV is emitted first, and create a stub containing the fully
+  // resolved address.
+  void *GVAddress = getPointerToGlobal(V, Reference, true);
+  void *StubAddr = Resolver.getGlobalValueIndirectSym(V, GVAddress);
+  
+  // Add the stub to the current function's list of referenced stubs, so we can
+  // deallocate them if the current function is ever freed.
+  AddStubToCurrentFunction(StubAddr);
+  
+  return StubAddr;
+}
+
+void JITEmitter::AddStubToCurrentFunction(void *StubAddr) {
+  if (!TheJIT->areDlsymStubsEnabled())
+    return;
+  
+  assert(CurFn && "Stub added to current function, but current function is 0!");
+  
+  SmallVectorImpl<void*> &StubsUsed = CurFnStubUses[CurFn];
+  StubsUsed.push_back(StubAddr);
+
+  SmallPtrSet<const Function *, 1> &FnRefs = StubFnRefs[StubAddr];
+  FnRefs.insert(CurFn);
+}
+
+static unsigned GetConstantPoolSizeInBytes(MachineConstantPool *MCP,
+                                           const TargetData *TD) {
+  const std::vector<MachineConstantPoolEntry> &Constants = MCP->getConstants();
+  if (Constants.empty()) return 0;
+
+  unsigned Size = 0;
+  for (unsigned i = 0, e = Constants.size(); i != e; ++i) {
+    MachineConstantPoolEntry CPE = Constants[i];
+    unsigned AlignMask = CPE.getAlignment() - 1;
+    Size = (Size + AlignMask) & ~AlignMask;
+    const Type *Ty = CPE.getType();
+    Size += TD->getTypeAllocSize(Ty);
+  }
+  return Size;
+}
+
+static unsigned GetJumpTableSizeInBytes(MachineJumpTableInfo *MJTI) {
+  const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
+  if (JT.empty()) return 0;
+  
+  unsigned NumEntries = 0;
+  for (unsigned i = 0, e = JT.size(); i != e; ++i)
+    NumEntries += JT[i].MBBs.size();
+
+  unsigned EntrySize = MJTI->getEntrySize();
+
+  return NumEntries * EntrySize;
+}
+
+static uintptr_t RoundUpToAlign(uintptr_t Size, unsigned Alignment) {
+  if (Alignment == 0) Alignment = 1;
+  // Since we do not know where the buffer will be allocated, be pessimistic. 
+  return Size + Alignment;
+}
+
+/// addSizeOfGlobal - add the size of the global (plus any alignment padding)
+/// into the running total Size.
+
+unsigned JITEmitter::addSizeOfGlobal(const GlobalVariable *GV, unsigned Size) {
+  const Type *ElTy = GV->getType()->getElementType();
+  size_t GVSize = (size_t)TheJIT->getTargetData()->getTypeAllocSize(ElTy);
+  size_t GVAlign = 
+      (size_t)TheJIT->getTargetData()->getPreferredAlignment(GV);
+  DOUT << "JIT: Adding in size " << GVSize << " alignment " << GVAlign;
+  DEBUG(GV->dump());
+  // Assume code section ends with worst possible alignment, so first
+  // variable needs maximal padding.
+  if (Size==0)
+    Size = 1;
+  Size = ((Size+GVAlign-1)/GVAlign)*GVAlign;
+  Size += GVSize;
+  return Size;
+}
+
+/// addSizeOfGlobalsInConstantVal - find any globals that we haven't seen yet
+/// but are referenced from the constant; put them in GVSet and add their
+/// size into the running total Size.
+
+unsigned JITEmitter::addSizeOfGlobalsInConstantVal(const Constant *C, 
+                                              unsigned Size) {
+  // If its undefined, return the garbage.
+  if (isa<UndefValue>(C))
+    return Size;
+
+  // If the value is a ConstantExpr
+  if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
+    Constant *Op0 = CE->getOperand(0);
+    switch (CE->getOpcode()) {
+    case Instruction::GetElementPtr:
+    case Instruction::Trunc:
+    case Instruction::ZExt:
+    case Instruction::SExt:
+    case Instruction::FPTrunc:
+    case Instruction::FPExt:
+    case Instruction::UIToFP:
+    case Instruction::SIToFP:
+    case Instruction::FPToUI:
+    case Instruction::FPToSI:
+    case Instruction::PtrToInt:
+    case Instruction::IntToPtr:
+    case Instruction::BitCast: {
+      Size = addSizeOfGlobalsInConstantVal(Op0, Size);
+      break;
+    }
+    case Instruction::Add:
+    case Instruction::Sub:
+    case Instruction::Mul:
+    case Instruction::UDiv:
+    case Instruction::SDiv:
+    case Instruction::URem:
+    case Instruction::SRem:
+    case Instruction::And:
+    case Instruction::Or:
+    case Instruction::Xor: {
+      Size = addSizeOfGlobalsInConstantVal(Op0, Size);
+      Size = addSizeOfGlobalsInConstantVal(CE->getOperand(1), Size);
+      break;
+    }
+    default: {
+       cerr << "ConstantExpr not handled: " << *CE << "\n";
+      abort();
+    }
+    }
+  }
+
+  if (C->getType()->getTypeID() == Type::PointerTyID)
+    if (const GlobalVariable* GV = dyn_cast<GlobalVariable>(C))
+      if (GVSet.insert(GV))
+        Size = addSizeOfGlobal(GV, Size);
+
+  return Size;
+}
+
+/// addSizeOfGLobalsInInitializer - handle any globals that we haven't seen yet
+/// but are referenced from the given initializer.
+
+unsigned JITEmitter::addSizeOfGlobalsInInitializer(const Constant *Init, 
+                                              unsigned Size) {
+  if (!isa<UndefValue>(Init) &&
+      !isa<ConstantVector>(Init) &&
+      !isa<ConstantAggregateZero>(Init) &&
+      !isa<ConstantArray>(Init) &&
+      !isa<ConstantStruct>(Init) &&
+      Init->getType()->isFirstClassType())
+    Size = addSizeOfGlobalsInConstantVal(Init, Size);
+  return Size;
+}
+
+/// GetSizeOfGlobalsInBytes - walk the code for the function, looking for
+/// globals; then walk the initializers of those globals looking for more.
+/// If their size has not been considered yet, add it into the running total
+/// Size.
+
+unsigned JITEmitter::GetSizeOfGlobalsInBytes(MachineFunction &MF) {
+  unsigned Size = 0;
+  GVSet.clear();
+
+  for (MachineFunction::iterator MBB = MF.begin(), E = MF.end(); 
+       MBB != E; ++MBB) {
+    for (MachineBasicBlock::const_iterator I = MBB->begin(), E = MBB->end();
+         I != E; ++I) {
+      const TargetInstrDesc &Desc = I->getDesc();
+      const MachineInstr &MI = *I;
+      unsigned NumOps = Desc.getNumOperands();
+      for (unsigned CurOp = 0; CurOp < NumOps; CurOp++) {
+        const MachineOperand &MO = MI.getOperand(CurOp);
+        if (MO.isGlobal()) {
+          GlobalValue* V = MO.getGlobal();
+          const GlobalVariable *GV = dyn_cast<const GlobalVariable>(V);
+          if (!GV)
+            continue;
+          // If seen in previous function, it will have an entry here.
+          if (TheJIT->getPointerToGlobalIfAvailable(GV))
+            continue;
+          // If seen earlier in this function, it will have an entry here.
+          // FIXME: it should be possible to combine these tables, by
+          // assuming the addresses of the new globals in this module
+          // start at 0 (or something) and adjusting them after codegen
+          // complete.  Another possibility is to grab a marker bit in GV.
+          if (GVSet.insert(GV))
+            // A variable as yet unseen.  Add in its size.
+            Size = addSizeOfGlobal(GV, Size);
+        }
+      }
+    }
+  }
+  DOUT << "JIT: About to look through initializers\n";
+  // Look for more globals that are referenced only from initializers.
+  // GVSet.end is computed each time because the set can grow as we go.
+  for (SmallPtrSet<const GlobalVariable *, 8>::iterator I = GVSet.begin(); 
+       I != GVSet.end(); I++) {
+    const GlobalVariable* GV = *I;
+    if (GV->hasInitializer())
+      Size = addSizeOfGlobalsInInitializer(GV->getInitializer(), Size);
+  }
+
+  return Size;
+}
+
+void JITEmitter::startFunction(MachineFunction &F) {
+  DOUT << "JIT: Starting CodeGen of Function "
+       << F.getFunction()->getName() << "\n";
+
+  uintptr_t ActualSize = 0;
+  // Set the memory writable, if it's not already
+  MemMgr->setMemoryWritable();
+  if (MemMgr->NeedsExactSize()) {
+    DOUT << "JIT: ExactSize\n";
+    const TargetInstrInfo* TII = F.getTarget().getInstrInfo();
+    MachineJumpTableInfo *MJTI = F.getJumpTableInfo();
+    MachineConstantPool *MCP = F.getConstantPool();
+    
+    // Ensure the constant pool/jump table info is at least 4-byte aligned.
+    ActualSize = RoundUpToAlign(ActualSize, 16);
+    
+    // Add the alignment of the constant pool
+    ActualSize = RoundUpToAlign(ActualSize, MCP->getConstantPoolAlignment());
+
+    // Add the constant pool size
+    ActualSize += GetConstantPoolSizeInBytes(MCP, TheJIT->getTargetData());
+
+    // Add the aligment of the jump table info
+    ActualSize = RoundUpToAlign(ActualSize, MJTI->getAlignment());
+
+    // Add the jump table size
+    ActualSize += GetJumpTableSizeInBytes(MJTI);
+    
+    // Add the alignment for the function
+    ActualSize = RoundUpToAlign(ActualSize,
+                                std::max(F.getFunction()->getAlignment(), 8U));
+
+    // Add the function size
+    ActualSize += TII->GetFunctionSizeInBytes(F);
+
+    DOUT << "JIT: ActualSize before globals " << ActualSize << "\n";
+    // Add the size of the globals that will be allocated after this function.
+    // These are all the ones referenced from this function that were not
+    // previously allocated.
+    ActualSize += GetSizeOfGlobalsInBytes(F);
+    DOUT << "JIT: ActualSize after globals " << ActualSize << "\n";
+  }
+
+  BufferBegin = CurBufferPtr = MemMgr->startFunctionBody(F.getFunction(),
+                                                         ActualSize);
+  BufferEnd = BufferBegin+ActualSize;
+  
+  // Ensure the constant pool/jump table info is at least 4-byte aligned.
+  emitAlignment(16);
+
+  emitConstantPool(F.getConstantPool());
+  initJumpTableInfo(F.getJumpTableInfo());
+
+  // About to start emitting the machine code for the function.
+  emitAlignment(std::max(F.getFunction()->getAlignment(), 8U));
+  TheJIT->updateGlobalMapping(F.getFunction(), CurBufferPtr);
+
+  MBBLocations.clear();
+}
+
+bool JITEmitter::finishFunction(MachineFunction &F) {
+  if (CurBufferPtr == BufferEnd) {
+    // FIXME: Allocate more space, then try again.
+    cerr << "JIT: Ran out of space for generated machine code!\n";
+    abort();
+  }
+  
+  emitJumpTableInfo(F.getJumpTableInfo());
+  
+  // FnStart is the start of the text, not the start of the constant pool and
+  // other per-function data.
+  uint8_t *FnStart =
+    (uint8_t *)TheJIT->getPointerToGlobalIfAvailable(F.getFunction());
+
+  // FnEnd is the end of the function's machine code.
+  uint8_t *FnEnd = CurBufferPtr;
+
+  if (!Relocations.empty()) {
+    CurFn = F.getFunction();
+    NumRelos += Relocations.size();
+
+    // Resolve the relocations to concrete pointers.
+    for (unsigned i = 0, e = Relocations.size(); i != e; ++i) {
+      MachineRelocation &MR = Relocations[i];
+      void *ResultPtr = 0;
+      if (!MR.letTargetResolve()) {
+        if (MR.isExternalSymbol()) {
+          ResultPtr = TheJIT->getPointerToNamedFunction(MR.getExternalSymbol(),
+                                                        false);
+          DOUT << "JIT: Map \'" << MR.getExternalSymbol() << "\' to ["
+               << ResultPtr << "]\n";  
+
+          // If the target REALLY wants a stub for this function, emit it now.
+          if (!MR.doesntNeedStub()) {
+            if (!TheJIT->areDlsymStubsEnabled()) {
+              ResultPtr = Resolver.getExternalFunctionStub(ResultPtr);
+            } else {
+              void *&Stub = ExtFnStubs[MR.getExternalSymbol()];
+              if (!Stub) {
+                Stub = Resolver.getExternalFunctionStub((void *)&Stub);
+                AddStubToCurrentFunction(Stub);
+              }
+              ResultPtr = Stub;
+            }
+          }
+        } else if (MR.isGlobalValue()) {
+          ResultPtr = getPointerToGlobal(MR.getGlobalValue(),
+                                         BufferBegin+MR.getMachineCodeOffset(),
+                                         MR.doesntNeedStub());
+        } else if (MR.isIndirectSymbol()) {
+          ResultPtr = getPointerToGVIndirectSym(MR.getGlobalValue(),
+                                          BufferBegin+MR.getMachineCodeOffset(),
+                                          MR.doesntNeedStub());
+        } else if (MR.isBasicBlock()) {
+          ResultPtr = (void*)getMachineBasicBlockAddress(MR.getBasicBlock());
+        } else if (MR.isConstantPoolIndex()) {
+          ResultPtr = (void*)getConstantPoolEntryAddress(MR.getConstantPoolIndex());
+        } else {
+          assert(MR.isJumpTableIndex());
+          ResultPtr=(void*)getJumpTableEntryAddress(MR.getJumpTableIndex());
+        }
+
+        MR.setResultPointer(ResultPtr);
+      }
+
+      // if we are managing the GOT and the relocation wants an index,
+      // give it one
+      if (MR.isGOTRelative() && MemMgr->isManagingGOT()) {
+        unsigned idx = Resolver.getGOTIndexForAddr(ResultPtr);
+        MR.setGOTIndex(idx);
+        if (((void**)MemMgr->getGOTBase())[idx] != ResultPtr) {
+          DOUT << "JIT: GOT was out of date for " << ResultPtr
+               << " pointing at " << ((void**)MemMgr->getGOTBase())[idx]
+               << "\n";
+          ((void**)MemMgr->getGOTBase())[idx] = ResultPtr;
+        }
+      }
+    }
+
+    CurFn = 0;
+    TheJIT->getJITInfo().relocate(BufferBegin, &Relocations[0],
+                                  Relocations.size(), MemMgr->getGOTBase());
+  }
+
+  // Update the GOT entry for F to point to the new code.
+  if (MemMgr->isManagingGOT()) {
+    unsigned idx = Resolver.getGOTIndexForAddr((void*)BufferBegin);
+    if (((void**)MemMgr->getGOTBase())[idx] != (void*)BufferBegin) {
+      DOUT << "JIT: GOT was out of date for " << (void*)BufferBegin
+           << " pointing at " << ((void**)MemMgr->getGOTBase())[idx] << "\n";
+      ((void**)MemMgr->getGOTBase())[idx] = (void*)BufferBegin;
+    }
+  }
+
+  // CurBufferPtr may have moved beyond FnEnd, due to memory allocation for
+  // global variables that were referenced in the relocations.
+  MemMgr->endFunctionBody(F.getFunction(), BufferBegin, CurBufferPtr);
+
+  if (CurBufferPtr == BufferEnd) {
+    // FIXME: Allocate more space, then try again.
+    cerr << "JIT: Ran out of space for generated machine code!\n";
+    abort();
+  }
+
+  BufferBegin = CurBufferPtr = 0;
+  NumBytes += FnEnd-FnStart;
+
+  // Invalidate the icache if necessary.
+  sys::Memory::InvalidateInstructionCache(FnStart, FnEnd-FnStart);
+  
+  // Add it to the JIT symbol table if the host wants it.
+  AddFunctionToSymbolTable(F.getFunction()->getNameStart(),
+                           FnStart, FnEnd-FnStart);
+
+  DOUT << "JIT: Finished CodeGen of [" << (void*)FnStart
+       << "] Function: " << F.getFunction()->getName()
+       << ": " << (FnEnd-FnStart) << " bytes of text, "
+       << Relocations.size() << " relocations\n";
+
+  if (MCI) {
+    MCI->setAddress(FnStart);
+    MCI->setSize(FnEnd-FnStart);
+  }
+
+  Relocations.clear();
+  ConstPoolAddresses.clear();
+
+  // Mark code region readable and executable if it's not so already.
+  MemMgr->setMemoryExecutable();
+
+#ifndef NDEBUG
+  {
+    if (sys::hasDisassembler()) {
+      DOUT << "JIT: Disassembled code:\n";
+      DOUT << sys::disassembleBuffer(FnStart, FnEnd-FnStart, (uintptr_t)FnStart);
+    } else {
+      DOUT << "JIT: Binary code:\n";
+      DOUT << std::hex;
+      uint8_t* q = FnStart;
+      for (int i = 0; q < FnEnd; q += 4, ++i) {
+        if (i == 4)
+          i = 0;
+        if (i == 0)
+          DOUT << "JIT: " << std::setw(8) << std::setfill('0')
+               << (long)(q - FnStart) << ": ";
+        bool Done = false;
+        for (int j = 3; j >= 0; --j) {
+          if (q + j >= FnEnd)
+            Done = true;
+          else
+            DOUT << std::setw(2) << std::setfill('0') << (unsigned short)q[j];
+        }
+        if (Done)
+          break;
+        DOUT << ' ';
+        if (i == 3)
+          DOUT << '\n';
+      }
+      DOUT << std::dec;
+      DOUT<< '\n';
+    }
+  }
+#endif
+  if (ExceptionHandling) {
+    uintptr_t ActualSize = 0;
+    SavedBufferBegin = BufferBegin;
+    SavedBufferEnd = BufferEnd;
+    SavedCurBufferPtr = CurBufferPtr;
+    
+    if (MemMgr->NeedsExactSize()) {
+      ActualSize = DE->GetDwarfTableSizeInBytes(F, *this, FnStart, FnEnd);
+    }
+
+    BufferBegin = CurBufferPtr = MemMgr->startExceptionTable(F.getFunction(),
+                                                             ActualSize);
+    BufferEnd = BufferBegin+ActualSize;
+    uint8_t* FrameRegister = DE->EmitDwarfTable(F, *this, FnStart, FnEnd);
+    MemMgr->endExceptionTable(F.getFunction(), BufferBegin, CurBufferPtr,
+                              FrameRegister);
+    BufferBegin = SavedBufferBegin;
+    BufferEnd = SavedBufferEnd;
+    CurBufferPtr = SavedCurBufferPtr;
+
+    TheJIT->RegisterTable(FrameRegister);
+  }
+
+  if (MMI)
+    MMI->EndFunction();
+ 
+  return false;
+}
+
+/// deallocateMemForFunction - Deallocate all memory for the specified
+/// function body.  Also drop any references the function has to stubs.
+void JITEmitter::deallocateMemForFunction(Function *F) {
+  MemMgr->deallocateMemForFunction(F);
+
+  // If the function did not reference any stubs, return.
+  if (CurFnStubUses.find(F) == CurFnStubUses.end())
+    return;
+  
+  // For each referenced stub, erase the reference to this function, and then
+  // erase the list of referenced stubs.
+  SmallVectorImpl<void *> &StubList = CurFnStubUses[F];
+  for (unsigned i = 0, e = StubList.size(); i != e; ++i) {
+    void *Stub = StubList[i];
+    
+    // If we already invalidated this stub for this function, continue.
+    if (StubFnRefs.count(Stub) == 0)
+      continue;
+      
+    SmallPtrSet<const Function *, 1> &FnRefs = StubFnRefs[Stub];
+    FnRefs.erase(F);
+    
+    // If this function was the last reference to the stub, invalidate the stub
+    // in the JITResolver.  Were there a memory manager deallocateStub routine,
+    // we could call that at this point too.
+    if (FnRefs.empty()) {
+      DOUT << "\nJIT: Invalidated Stub at [" << Stub << "]\n";
+      StubFnRefs.erase(Stub);
+
+      // Invalidate the stub.  If it is a GV stub, update the JIT's global
+      // mapping for that GV to zero, otherwise, search the string map of
+      // external function names to stubs and remove the entry for this stub.
+      GlobalValue *GV = Resolver.invalidateStub(Stub);
+      if (GV) {
+        TheJIT->updateGlobalMapping(GV, 0);
+      } else {
+        for (StringMapIterator<void*> i = ExtFnStubs.begin(),
+             e = ExtFnStubs.end(); i != e; ++i) {
+          if (i->second == Stub) {
+            ExtFnStubs.erase(i);
+            break;
+          }
+        }
+      }
+    }
+  }
+  CurFnStubUses.erase(F);
+}
+
+
+void* JITEmitter::allocateSpace(uintptr_t Size, unsigned Alignment) {
+  if (BufferBegin)
+    return JITCodeEmitter::allocateSpace(Size, Alignment);
+
+  // create a new memory block if there is no active one.
+  // care must be taken so that BufferBegin is invalidated when a
+  // block is trimmed
+  BufferBegin = CurBufferPtr = MemMgr->allocateSpace(Size, Alignment);
+  BufferEnd = BufferBegin+Size;
+  return CurBufferPtr;
+}
+
+void JITEmitter::emitConstantPool(MachineConstantPool *MCP) {
+  if (TheJIT->getJITInfo().hasCustomConstantPool())
+    return;
+
+  const std::vector<MachineConstantPoolEntry> &Constants = MCP->getConstants();
+  if (Constants.empty()) return;
+
+  unsigned Size = GetConstantPoolSizeInBytes(MCP, TheJIT->getTargetData());
+  unsigned Align = MCP->getConstantPoolAlignment();
+  ConstantPoolBase = allocateSpace(Size, Align);
+  ConstantPool = MCP;
+
+  if (ConstantPoolBase == 0) return;  // Buffer overflow.
+
+  DOUT << "JIT: Emitted constant pool at [" << ConstantPoolBase
+       << "] (size: " << Size << ", alignment: " << Align << ")\n";
+
+  // Initialize the memory for all of the constant pool entries.
+  unsigned Offset = 0;
+  for (unsigned i = 0, e = Constants.size(); i != e; ++i) {
+    MachineConstantPoolEntry CPE = Constants[i];
+    unsigned AlignMask = CPE.getAlignment() - 1;
+    Offset = (Offset + AlignMask) & ~AlignMask;
+
+    uintptr_t CAddr = (uintptr_t)ConstantPoolBase + Offset;
+    ConstPoolAddresses.push_back(CAddr);
+    if (CPE.isMachineConstantPoolEntry()) {
+      // FIXME: add support to lower machine constant pool values into bytes!
+      cerr << "Initialize memory with machine specific constant pool entry"
+           << " has not been implemented!\n";
+      abort();
+    }
+    TheJIT->InitializeMemory(CPE.Val.ConstVal, (void*)CAddr);
+    DOUT << "JIT:   CP" << i << " at [0x"
+         << std::hex << CAddr << std::dec << "]\n";
+
+    const Type *Ty = CPE.Val.ConstVal->getType();
+    Offset += TheJIT->getTargetData()->getTypeAllocSize(Ty);
+  }
+}
+
+void JITEmitter::initJumpTableInfo(MachineJumpTableInfo *MJTI) {
+  if (TheJIT->getJITInfo().hasCustomJumpTables())
+    return;
+
+  const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
+  if (JT.empty()) return;
+  
+  unsigned NumEntries = 0;
+  for (unsigned i = 0, e = JT.size(); i != e; ++i)
+    NumEntries += JT[i].MBBs.size();
+
+  unsigned EntrySize = MJTI->getEntrySize();
+
+  // Just allocate space for all the jump tables now.  We will fix up the actual
+  // MBB entries in the tables after we emit the code for each block, since then
+  // we will know the final locations of the MBBs in memory.
+  JumpTable = MJTI;
+  JumpTableBase = allocateSpace(NumEntries * EntrySize, MJTI->getAlignment());
+}
+
+void JITEmitter::emitJumpTableInfo(MachineJumpTableInfo *MJTI) {
+  if (TheJIT->getJITInfo().hasCustomJumpTables())
+    return;
+
+  const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
+  if (JT.empty() || JumpTableBase == 0) return;
+  
+  if (TargetMachine::getRelocationModel() == Reloc::PIC_) {
+    assert(MJTI->getEntrySize() == 4 && "Cross JIT'ing?");
+    // For each jump table, place the offset from the beginning of the table
+    // to the target address.
+    int *SlotPtr = (int*)JumpTableBase;
+
+    for (unsigned i = 0, e = JT.size(); i != e; ++i) {
+      const std::vector<MachineBasicBlock*> &MBBs = JT[i].MBBs;
+      // Store the offset of the basic block for this jump table slot in the
+      // memory we allocated for the jump table in 'initJumpTableInfo'
+      uintptr_t Base = (uintptr_t)SlotPtr;
+      for (unsigned mi = 0, me = MBBs.size(); mi != me; ++mi) {
+        uintptr_t MBBAddr = getMachineBasicBlockAddress(MBBs[mi]);
+        *SlotPtr++ = TheJIT->getJITInfo().getPICJumpTableEntry(MBBAddr, Base);
+      }
+    }
+  } else {
+    assert(MJTI->getEntrySize() == sizeof(void*) && "Cross JIT'ing?");
+    
+    // For each jump table, map each target in the jump table to the address of 
+    // an emitted MachineBasicBlock.
+    intptr_t *SlotPtr = (intptr_t*)JumpTableBase;
+
+    for (unsigned i = 0, e = JT.size(); i != e; ++i) {
+      const std::vector<MachineBasicBlock*> &MBBs = JT[i].MBBs;
+      // Store the address of the basic block for this jump table slot in the
+      // memory we allocated for the jump table in 'initJumpTableInfo'
+      for (unsigned mi = 0, me = MBBs.size(); mi != me; ++mi)
+        *SlotPtr++ = getMachineBasicBlockAddress(MBBs[mi]);
+    }
+  }
+}
+
+void JITEmitter::startGVStub(const GlobalValue* GV, unsigned StubSize,
+                             unsigned Alignment) {
+  SavedBufferBegin = BufferBegin;
+  SavedBufferEnd = BufferEnd;
+  SavedCurBufferPtr = CurBufferPtr;
+  
+  BufferBegin = CurBufferPtr = MemMgr->allocateStub(GV, StubSize, Alignment);
+  BufferEnd = BufferBegin+StubSize+1;
+}
+
+void JITEmitter::startGVStub(const GlobalValue* GV, void *Buffer,
+                             unsigned StubSize) {
+  SavedBufferBegin = BufferBegin;
+  SavedBufferEnd = BufferEnd;
+  SavedCurBufferPtr = CurBufferPtr;
+  
+  BufferBegin = CurBufferPtr = (uint8_t *)Buffer;
+  BufferEnd = BufferBegin+StubSize+1;
+}
+
+void *JITEmitter::finishGVStub(const GlobalValue* GV) {
+  NumBytes += getCurrentPCOffset();
+  std::swap(SavedBufferBegin, BufferBegin);
+  BufferEnd = SavedBufferEnd;
+  CurBufferPtr = SavedCurBufferPtr;
+  return SavedBufferBegin;
+}
+
+// getConstantPoolEntryAddress - Return the address of the 'ConstantNum' entry
+// in the constant pool that was last emitted with the 'emitConstantPool'
+// method.
+//
+uintptr_t JITEmitter::getConstantPoolEntryAddress(unsigned ConstantNum) const {
+  assert(ConstantNum < ConstantPool->getConstants().size() &&
+         "Invalid ConstantPoolIndex!");
+  return ConstPoolAddresses[ConstantNum];
+}
+
+// getJumpTableEntryAddress - Return the address of the JumpTable with index
+// 'Index' in the jumpp table that was last initialized with 'initJumpTableInfo'
+//
+uintptr_t JITEmitter::getJumpTableEntryAddress(unsigned Index) const {
+  const std::vector<MachineJumpTableEntry> &JT = JumpTable->getJumpTables();
+  assert(Index < JT.size() && "Invalid jump table index!");
+  
+  unsigned Offset = 0;
+  unsigned EntrySize = JumpTable->getEntrySize();
+  
+  for (unsigned i = 0; i < Index; ++i)
+    Offset += JT[i].MBBs.size();
+  
+   Offset *= EntrySize;
+  
+  return (uintptr_t)((char *)JumpTableBase + Offset);
+}
+
+//===----------------------------------------------------------------------===//
+//  Public interface to this file
+//===----------------------------------------------------------------------===//
+
+JITCodeEmitter *JIT::createEmitter(JIT &jit, JITMemoryManager *JMM) {
+  return new JITEmitter(jit, JMM);
+}
+
+// getPointerToNamedFunction - This function is used as a global wrapper to
+// JIT::getPointerToNamedFunction for the purpose of resolving symbols when
+// bugpoint is debugging the JIT. In that scenario, we are loading an .so and
+// need to resolve function(s) that are being mis-codegenerated, so we need to
+// resolve their addresses at runtime, and this is the way to do it.
+extern "C" {
+  void *getPointerToNamedFunction(const char *Name) {
+    if (Function *F = TheJIT->FindFunctionNamed(Name))
+      return TheJIT->getPointerToFunction(F);
+    return TheJIT->getPointerToNamedFunction(Name);
+  }
+}
+
+// getPointerToFunctionOrStub - If the specified function has been
+// code-gen'd, return a pointer to the function.  If not, compile it, or use
+// a stub to implement lazy compilation if available.
+//
+void *JIT::getPointerToFunctionOrStub(Function *F) {
+  // If we have already code generated the function, just return the address.
+  if (void *Addr = getPointerToGlobalIfAvailable(F))
+    return Addr;
+  
+  // Get a stub if the target supports it.
+  assert(isa<JITEmitter>(JCE) && "Unexpected MCE?");
+  JITEmitter *JE = cast<JITEmitter>(getCodeEmitter());
+  return JE->getJITResolver().getFunctionStub(F);
+}
+
+void JIT::registerMachineCodeInfo(MachineCodeInfo *mc) {
+  assert(isa<JITEmitter>(JCE) && "Unexpected MCE?");
+  JITEmitter *JE = cast<JITEmitter>(getCodeEmitter());
+
+  JE->setMachineCodeInfo(mc);
+}
+
+void JIT::updateFunctionStub(Function *F) {
+  // Get the empty stub we generated earlier.
+  assert(isa<JITEmitter>(JCE) && "Unexpected MCE?");
+  JITEmitter *JE = cast<JITEmitter>(getCodeEmitter());
+  void *Stub = JE->getJITResolver().getFunctionStub(F);
+
+  // Tell the target jit info to rewrite the stub at the specified address,
+  // rather than creating a new one.
+  void *Addr = getPointerToGlobalIfAvailable(F);
+  getJITInfo().emitFunctionStubAtAddr(F, Addr, Stub, *getCodeEmitter());
+}
+
+/// updateDlsymStubTable - Emit the data necessary to relocate the stubs
+/// that were emitted during code generation.
+///
+void JIT::updateDlsymStubTable() {
+  assert(isa<JITEmitter>(JCE) && "Unexpected MCE?");
+  JITEmitter *JE = cast<JITEmitter>(getCodeEmitter());
+  
+  SmallVector<GlobalValue*, 8> GVs;
+  SmallVector<void*, 8> Ptrs;
+  const StringMap<void *> &ExtFns = JE->getExternalFnStubs();
+
+  JE->getJITResolver().getRelocatableGVs(GVs, Ptrs);
+
+  unsigned nStubs = GVs.size() + ExtFns.size();
+  
+  // If there are no relocatable stubs, return.
+  if (nStubs == 0)
+    return;
+
+  // If there are no new relocatable stubs, return.
+  void *CurTable = JE->getMemMgr()->getDlsymTable();
+  if (CurTable && (*(unsigned *)CurTable == nStubs))
+    return;
+  
+  // Calculate the size of the stub info
+  unsigned offset = 4 + 4 * nStubs + sizeof(intptr_t) * nStubs;
+  
+  SmallVector<unsigned, 8> Offsets;
+  for (unsigned i = 0; i != GVs.size(); ++i) {
+    Offsets.push_back(offset);
+    offset += GVs[i]->getName().length() + 1;
+  }
+  for (StringMapConstIterator<void*> i = ExtFns.begin(), e = ExtFns.end(); 
+       i != e; ++i) {
+    Offsets.push_back(offset);
+    offset += strlen(i->first()) + 1;
+  }
+  
+  // Allocate space for the new "stub", which contains the dlsym table.
+  JE->startGVStub(0, offset, 4);
+  
+  // Emit the number of records
+  JE->emitInt32(nStubs);
+  
+  // Emit the string offsets
+  for (unsigned i = 0; i != nStubs; ++i)
+    JE->emitInt32(Offsets[i]);
+  
+  // Emit the pointers.  Verify that they are at least 2-byte aligned, and set
+  // the low bit to 0 == GV, 1 == Function, so that the client code doing the
+  // relocation can write the relocated pointer at the appropriate place in
+  // the stub.
+  for (unsigned i = 0; i != GVs.size(); ++i) {
+    intptr_t Ptr = (intptr_t)Ptrs[i];
+    assert((Ptr & 1) == 0 && "Stub pointers must be at least 2-byte aligned!");
+    
+    if (isa<Function>(GVs[i]))
+      Ptr |= (intptr_t)1;
+           
+    if (sizeof(Ptr) == 8)
+      JE->emitInt64(Ptr);
+    else
+      JE->emitInt32(Ptr);
+  }
+  for (StringMapConstIterator<void*> i = ExtFns.begin(), e = ExtFns.end(); 
+       i != e; ++i) {
+    intptr_t Ptr = (intptr_t)i->second | 1;
+
+    if (sizeof(Ptr) == 8)
+      JE->emitInt64(Ptr);
+    else
+      JE->emitInt32(Ptr);
+  }
+  
+  // Emit the strings.
+  for (unsigned i = 0; i != GVs.size(); ++i)
+    JE->emitString(GVs[i]->getName());
+  for (StringMapConstIterator<void*> i = ExtFns.begin(), e = ExtFns.end(); 
+       i != e; ++i)
+    JE->emitString(i->first());
+  
+  // Tell the JIT memory manager where it is.  The JIT Memory Manager will
+  // deallocate space for the old one, if one existed.
+  JE->getMemMgr()->SetDlsymTable(JE->finishGVStub(0));
+}
+
+/// freeMachineCodeForFunction - release machine code memory for given Function.
+///
+void JIT::freeMachineCodeForFunction(Function *F) {
+
+  // Delete translation for this from the ExecutionEngine, so it will get
+  // retranslated next time it is used.
+  void *OldPtr = updateGlobalMapping(F, 0);
+
+  if (OldPtr)
+    RemoveFunctionFromSymbolTable(OldPtr);
+
+  // Free the actual memory for the function body and related stuff.
+  assert(isa<JITEmitter>(JCE) && "Unexpected MCE?");
+  cast<JITEmitter>(JCE)->deallocateMemForFunction(F);
+}
+