It's not necessary to do rounding for alloca operations when the requested

alignment is equal to the stack alignment.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40004 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 799 insertions, 0 deletions

diff --git a/lib/CodeGen/IntrinsicLowering.cpp b/lib/CodeGen/IntrinsicLowering.cpp
new file mode 100644
index 0000000..8ae4df6
--- /dev/null
+++ b/lib/CodeGen/IntrinsicLowering.cpp
@@ -0,0 +1,799 @@
+//===-- IntrinsicLowering.cpp - Intrinsic Lowering default implementation -===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the IntrinsicLowering class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Module.h"
+#include "llvm/Instructions.h"
+#include "llvm/Type.h"
+#include "llvm/CodeGen/IntrinsicLowering.h"
+#include "llvm/Support/Streams.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/ADT/SmallVector.h"
+using namespace llvm;
+
+template <class ArgIt>
+static void EnsureFunctionExists(Module &M, const char *Name,
+                                 ArgIt ArgBegin, ArgIt ArgEnd,
+                                 const Type *RetTy) {
+  // Insert a correctly-typed definition now.
+  std::vector<const Type *> ParamTys;
+  for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
+    ParamTys.push_back(I->getType());
+  M.getOrInsertFunction(Name, FunctionType::get(RetTy, ParamTys, false));
+}
+
+/// ReplaceCallWith - This function is used when we want to lower an intrinsic
+/// call to a call of an external function.  This handles hard cases such as
+/// when there was already a prototype for the external function, and if that
+/// prototype doesn't match the arguments we expect to pass in.
+template <class ArgIt>
+static CallInst *ReplaceCallWith(const char *NewFn, CallInst *CI,
+                                 ArgIt ArgBegin, ArgIt ArgEnd,
+                                 const Type *RetTy, Constant *&FCache) {
+  if (!FCache) {
+    // If we haven't already looked up this function, check to see if the
+    // program already contains a function with this name.
+    Module *M = CI->getParent()->getParent()->getParent();
+    // Get or insert the definition now.
+    std::vector<const Type *> ParamTys;
+    for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
+      ParamTys.push_back((*I)->getType());
+    FCache = M->getOrInsertFunction(NewFn,
+                                    FunctionType::get(RetTy, ParamTys, false));
+  }
+
+  SmallVector<Value*, 8> Operands(ArgBegin, ArgEnd);
+  CallInst *NewCI = new CallInst(FCache, &Operands[0], Operands.size(),
+                                 CI->getName(), CI);
+  if (!CI->use_empty())
+    CI->replaceAllUsesWith(NewCI);
+  return NewCI;
+}
+
+void IntrinsicLowering::AddPrototypes(Module &M) {
+  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
+    if (I->isDeclaration() && !I->use_empty())
+      switch (I->getIntrinsicID()) {
+      default: break;
+      case Intrinsic::setjmp:
+        EnsureFunctionExists(M, "setjmp", I->arg_begin(), I->arg_end(),
+                             Type::Int32Ty);
+        break;
+      case Intrinsic::longjmp:
+        EnsureFunctionExists(M, "longjmp", I->arg_begin(), I->arg_end(),
+                             Type::VoidTy);
+        break;
+      case Intrinsic::siglongjmp:
+        EnsureFunctionExists(M, "abort", I->arg_end(), I->arg_end(),
+                             Type::VoidTy);
+        break;
+      case Intrinsic::memcpy_i32:
+      case Intrinsic::memcpy_i64:
+        M.getOrInsertFunction("memcpy", PointerType::get(Type::Int8Ty),
+                              PointerType::get(Type::Int8Ty), 
+                              PointerType::get(Type::Int8Ty), 
+                              TD.getIntPtrType(), (Type *)0);
+        break;
+      case Intrinsic::memmove_i32:
+      case Intrinsic::memmove_i64:
+        M.getOrInsertFunction("memmove", PointerType::get(Type::Int8Ty),
+                              PointerType::get(Type::Int8Ty), 
+                              PointerType::get(Type::Int8Ty), 
+                              TD.getIntPtrType(), (Type *)0);
+        break;
+      case Intrinsic::memset_i32:
+      case Intrinsic::memset_i64:
+        M.getOrInsertFunction("memset", PointerType::get(Type::Int8Ty),
+                              PointerType::get(Type::Int8Ty), Type::Int32Ty, 
+                              TD.getIntPtrType(), (Type *)0);
+        break;
+      case Intrinsic::sqrt_f32:
+      case Intrinsic::sqrt_f64:
+        if(I->arg_begin()->getType() == Type::FloatTy)
+          EnsureFunctionExists(M, "sqrtf", I->arg_begin(), I->arg_end(),
+                               Type::FloatTy);
+        else
+          EnsureFunctionExists(M, "sqrt", I->arg_begin(), I->arg_end(),
+                               Type::DoubleTy);
+        break;
+      }
+}
+
+/// LowerBSWAP - Emit the code to lower bswap of V before the specified
+/// instruction IP.
+static Value *LowerBSWAP(Value *V, Instruction *IP) {
+  assert(V->getType()->isInteger() && "Can't bswap a non-integer type!");
+
+  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
+  
+  switch(BitSize) {
+  default: assert(0 && "Unhandled type size of value to byteswap!");
+  case 16: {
+    Value *Tmp1 = BinaryOperator::createShl(V,
+                                ConstantInt::get(V->getType(),8),"bswap.2",IP);
+    Value *Tmp2 = BinaryOperator::createLShr(V,
+                                ConstantInt::get(V->getType(),8),"bswap.1",IP);
+    V = BinaryOperator::createOr(Tmp1, Tmp2, "bswap.i16", IP);
+    break;
+  }
+  case 32: {
+    Value *Tmp4 = BinaryOperator::createShl(V,
+                              ConstantInt::get(V->getType(),24),"bswap.4", IP);
+    Value *Tmp3 = BinaryOperator::createShl(V,
+                              ConstantInt::get(V->getType(),8),"bswap.3",IP);
+    Value *Tmp2 = BinaryOperator::createLShr(V,
+                              ConstantInt::get(V->getType(),8),"bswap.2",IP);
+    Value *Tmp1 = BinaryOperator::createLShr(V,
+                              ConstantInt::get(V->getType(),24),"bswap.1", IP);
+    Tmp3 = BinaryOperator::createAnd(Tmp3, 
+                                     ConstantInt::get(Type::Int32Ty, 0xFF0000),
+                                     "bswap.and3", IP);
+    Tmp2 = BinaryOperator::createAnd(Tmp2, 
+                                     ConstantInt::get(Type::Int32Ty, 0xFF00),
+                                     "bswap.and2", IP);
+    Tmp4 = BinaryOperator::createOr(Tmp4, Tmp3, "bswap.or1", IP);
+    Tmp2 = BinaryOperator::createOr(Tmp2, Tmp1, "bswap.or2", IP);
+    V = BinaryOperator::createOr(Tmp4, Tmp2, "bswap.i32", IP);
+    break;
+  }
+  case 64: {
+    Value *Tmp8 = BinaryOperator::createShl(V,
+                              ConstantInt::get(V->getType(),56),"bswap.8", IP);
+    Value *Tmp7 = BinaryOperator::createShl(V,
+                              ConstantInt::get(V->getType(),40),"bswap.7", IP);
+    Value *Tmp6 = BinaryOperator::createShl(V,
+                              ConstantInt::get(V->getType(),24),"bswap.6", IP);
+    Value *Tmp5 = BinaryOperator::createShl(V,
+                              ConstantInt::get(V->getType(),8),"bswap.5", IP);
+    Value* Tmp4 = BinaryOperator::createLShr(V,
+                              ConstantInt::get(V->getType(),8),"bswap.4", IP);
+    Value* Tmp3 = BinaryOperator::createLShr(V,
+                              ConstantInt::get(V->getType(),24),"bswap.3", IP);
+    Value* Tmp2 = BinaryOperator::createLShr(V,
+                              ConstantInt::get(V->getType(),40),"bswap.2", IP);
+    Value* Tmp1 = BinaryOperator::createLShr(V,
+                              ConstantInt::get(V->getType(),56),"bswap.1", IP);
+    Tmp7 = BinaryOperator::createAnd(Tmp7,
+                             ConstantInt::get(Type::Int64Ty, 
+                               0xFF000000000000ULL),
+                             "bswap.and7", IP);
+    Tmp6 = BinaryOperator::createAnd(Tmp6,
+                             ConstantInt::get(Type::Int64Ty, 0xFF0000000000ULL),
+                             "bswap.and6", IP);
+    Tmp5 = BinaryOperator::createAnd(Tmp5,
+                             ConstantInt::get(Type::Int64Ty, 0xFF00000000ULL),
+                             "bswap.and5", IP);
+    Tmp4 = BinaryOperator::createAnd(Tmp4,
+                             ConstantInt::get(Type::Int64Ty, 0xFF000000ULL),
+                             "bswap.and4", IP);
+    Tmp3 = BinaryOperator::createAnd(Tmp3,
+                             ConstantInt::get(Type::Int64Ty, 0xFF0000ULL),
+                             "bswap.and3", IP);
+    Tmp2 = BinaryOperator::createAnd(Tmp2,
+                             ConstantInt::get(Type::Int64Ty, 0xFF00ULL),
+                             "bswap.and2", IP);
+    Tmp8 = BinaryOperator::createOr(Tmp8, Tmp7, "bswap.or1", IP);
+    Tmp6 = BinaryOperator::createOr(Tmp6, Tmp5, "bswap.or2", IP);
+    Tmp4 = BinaryOperator::createOr(Tmp4, Tmp3, "bswap.or3", IP);
+    Tmp2 = BinaryOperator::createOr(Tmp2, Tmp1, "bswap.or4", IP);
+    Tmp8 = BinaryOperator::createOr(Tmp8, Tmp6, "bswap.or5", IP);
+    Tmp4 = BinaryOperator::createOr(Tmp4, Tmp2, "bswap.or6", IP);
+    V = BinaryOperator::createOr(Tmp8, Tmp4, "bswap.i64", IP);
+    break;
+  }
+  }
+  return V;
+}
+
+/// LowerCTPOP - Emit the code to lower ctpop of V before the specified
+/// instruction IP.
+static Value *LowerCTPOP(Value *V, Instruction *IP) {
+  assert(V->getType()->isInteger() && "Can't ctpop a non-integer type!");
+
+  static const uint64_t MaskValues[6] = {
+    0x5555555555555555ULL, 0x3333333333333333ULL,
+    0x0F0F0F0F0F0F0F0FULL, 0x00FF00FF00FF00FFULL,
+    0x0000FFFF0000FFFFULL, 0x00000000FFFFFFFFULL
+  };
+
+  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
+  unsigned WordSize = (BitSize + 63) / 64;
+  Value *Count = ConstantInt::get(V->getType(), 0);
+
+  for (unsigned n = 0; n < WordSize; ++n) {
+    Value *PartValue = V;
+    for (unsigned i = 1, ct = 0; i < (BitSize>64 ? 64 : BitSize); 
+         i <<= 1, ++ct) {
+      Value *MaskCst = ConstantInt::get(V->getType(), MaskValues[ct]);
+      Value *LHS = BinaryOperator::createAnd(
+                     PartValue, MaskCst, "cppop.and1", IP);
+      Value *VShift = BinaryOperator::createLShr(PartValue,
+                        ConstantInt::get(V->getType(), i), "ctpop.sh", IP);
+      Value *RHS = BinaryOperator::createAnd(VShift, MaskCst, "cppop.and2", IP);
+      PartValue = BinaryOperator::createAdd(LHS, RHS, "ctpop.step", IP);
+    }
+    Count = BinaryOperator::createAdd(PartValue, Count, "ctpop.part", IP);
+    if (BitSize > 64) {
+      V = BinaryOperator::createLShr(V, ConstantInt::get(V->getType(), 64), 
+                                     "ctpop.part.sh", IP);
+      BitSize -= 64;
+    }
+  }
+
+  return CastInst::createIntegerCast(Count, Type::Int32Ty, false, "ctpop", IP);
+}
+
+/// LowerCTLZ - Emit the code to lower ctlz of V before the specified
+/// instruction IP.
+static Value *LowerCTLZ(Value *V, Instruction *IP) {
+
+  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
+  for (unsigned i = 1; i < BitSize; i <<= 1) {
+    Value *ShVal = ConstantInt::get(V->getType(), i);
+    ShVal = BinaryOperator::createLShr(V, ShVal, "ctlz.sh", IP);
+    V = BinaryOperator::createOr(V, ShVal, "ctlz.step", IP);
+  }
+
+  V = BinaryOperator::createNot(V, "", IP);
+  return LowerCTPOP(V, IP);
+}
+
+/// Convert the llvm.part.select.iX.iY intrinsic. This intrinsic takes 
+/// three integer arguments. The first argument is the Value from which the
+/// bits will be selected. It may be of any bit width. The second and third
+/// arguments specify a range of bits to select with the second argument 
+/// specifying the low bit and the third argument specifying the high bit. Both
+/// must be type i32. The result is the corresponding selected bits from the
+/// Value in the same width as the Value (first argument). If the low bit index
+/// is higher than the high bit index then the inverse selection is done and 
+/// the bits are returned in inverse order. 
+/// @brief Lowering of llvm.part.select intrinsic.
+static Instruction *LowerPartSelect(CallInst *CI) {
+  // Make sure we're dealing with a part select intrinsic here
+  Function *F = CI->getCalledFunction();
+  const FunctionType *FT = F->getFunctionType();
+  if (!F->isDeclaration() || !FT->getReturnType()->isInteger() ||
+      FT->getNumParams() != 3 || !FT->getParamType(0)->isInteger() ||
+      !FT->getParamType(1)->isInteger() || !FT->getParamType(2)->isInteger())
+    return CI;
+
+  // Get the intrinsic implementation function by converting all the . to _
+  // in the intrinsic's function name and then reconstructing the function
+  // declaration.
+  std::string Name(F->getName());
+  for (unsigned i = 4; i < Name.length(); ++i)
+    if (Name[i] == '.')
+      Name[i] = '_';
+  Module* M = F->getParent();
+  F = cast<Function>(M->getOrInsertFunction(Name, FT));
+  F->setLinkage(GlobalValue::WeakLinkage);
+
+  // If we haven't defined the impl function yet, do so now
+  if (F->isDeclaration()) {
+
+    // Get the arguments to the function
+    Function::arg_iterator args = F->arg_begin();
+    Value* Val = args++; Val->setName("Val");
+    Value* Lo = args++; Lo->setName("Lo");
+    Value* Hi  = args++; Hi->setName("High");
+
+    // We want to select a range of bits here such that [Hi, Lo] is shifted
+    // down to the low bits. However, it is quite possible that Hi is smaller
+    // than Lo in which case the bits have to be reversed. 
+    
+    // Create the blocks we will need for the two cases (forward, reverse)
+    BasicBlock* CurBB   = new BasicBlock("entry", F);
+    BasicBlock *RevSize = new BasicBlock("revsize", CurBB->getParent());
+    BasicBlock *FwdSize = new BasicBlock("fwdsize", CurBB->getParent());
+    BasicBlock *Compute = new BasicBlock("compute", CurBB->getParent());
+    BasicBlock *Reverse = new BasicBlock("reverse", CurBB->getParent());
+    BasicBlock *RsltBlk = new BasicBlock("result",  CurBB->getParent());
+
+    // Cast Hi and Lo to the size of Val so the widths are all the same
+    if (Hi->getType() != Val->getType())
+      Hi = CastInst::createIntegerCast(Hi, Val->getType(), false, 
+                                         "tmp", CurBB);
+    if (Lo->getType() != Val->getType())
+      Lo = CastInst::createIntegerCast(Lo, Val->getType(), false, 
+                                          "tmp", CurBB);
+
+    // Compute a few things that both cases will need, up front.
+    Constant* Zero = ConstantInt::get(Val->getType(), 0);
+    Constant* One = ConstantInt::get(Val->getType(), 1);
+    Constant* AllOnes = ConstantInt::getAllOnesValue(Val->getType());
+
+    // Compare the Hi and Lo bit positions. This is used to determine 
+    // which case we have (forward or reverse)
+    ICmpInst *Cmp = new ICmpInst(ICmpInst::ICMP_ULT, Hi, Lo, "less",CurBB);
+    new BranchInst(RevSize, FwdSize, Cmp, CurBB);
+
+    // First, copmute the number of bits in the forward case.
+    Instruction* FBitSize = 
+      BinaryOperator::createSub(Hi, Lo,"fbits", FwdSize);
+    new BranchInst(Compute, FwdSize);
+
+    // Second, compute the number of bits in the reverse case.
+    Instruction* RBitSize = 
+      BinaryOperator::createSub(Lo, Hi, "rbits", RevSize);
+    new BranchInst(Compute, RevSize);
+
+    // Now, compute the bit range. Start by getting the bitsize and the shift
+    // amount (either Hi or Lo) from PHI nodes. Then we compute a mask for 
+    // the number of bits we want in the range. We shift the bits down to the 
+    // least significant bits, apply the mask to zero out unwanted high bits, 
+    // and we have computed the "forward" result. It may still need to be 
+    // reversed.
+
+    // Get the BitSize from one of the two subtractions
+    PHINode *BitSize = new PHINode(Val->getType(), "bits", Compute);
+    BitSize->reserveOperandSpace(2);
+    BitSize->addIncoming(FBitSize, FwdSize);
+    BitSize->addIncoming(RBitSize, RevSize);
+
+    // Get the ShiftAmount as the smaller of Hi/Lo
+    PHINode *ShiftAmt = new PHINode(Val->getType(), "shiftamt", Compute);
+    ShiftAmt->reserveOperandSpace(2);
+    ShiftAmt->addIncoming(Lo, FwdSize);
+    ShiftAmt->addIncoming(Hi, RevSize);
+
+    // Increment the bit size
+    Instruction *BitSizePlusOne = 
+      BinaryOperator::createAdd(BitSize, One, "bits", Compute);
+
+    // Create a Mask to zero out the high order bits.
+    Instruction* Mask = 
+      BinaryOperator::createShl(AllOnes, BitSizePlusOne, "mask", Compute);
+    Mask = BinaryOperator::createNot(Mask, "mask", Compute);
+
+    // Shift the bits down and apply the mask
+    Instruction* FRes = 
+      BinaryOperator::createLShr(Val, ShiftAmt, "fres", Compute);
+    FRes = BinaryOperator::createAnd(FRes, Mask, "fres", Compute);
+    new BranchInst(Reverse, RsltBlk, Cmp, Compute);
+
+    // In the Reverse block we have the mask already in FRes but we must reverse
+    // it by shifting FRes bits right and putting them in RRes by shifting them 
+    // in from left.
+
+    // First set up our loop counters
+    PHINode *Count = new PHINode(Val->getType(), "count", Reverse);
+    Count->reserveOperandSpace(2);
+    Count->addIncoming(BitSizePlusOne, Compute);
+
+    // Next, get the value that we are shifting.
+    PHINode *BitsToShift   = new PHINode(Val->getType(), "val", Reverse);
+    BitsToShift->reserveOperandSpace(2);
+    BitsToShift->addIncoming(FRes, Compute);
+
+    // Finally, get the result of the last computation
+    PHINode *RRes  = new PHINode(Val->getType(), "rres", Reverse);
+    RRes->reserveOperandSpace(2);
+    RRes->addIncoming(Zero, Compute);
+
+    // Decrement the counter
+    Instruction *Decr = BinaryOperator::createSub(Count, One, "decr", Reverse);
+    Count->addIncoming(Decr, Reverse);
+
+    // Compute the Bit that we want to move
+    Instruction *Bit = 
+      BinaryOperator::createAnd(BitsToShift, One, "bit", Reverse);
+
+    // Compute the new value for next iteration.
+    Instruction *NewVal = 
+      BinaryOperator::createLShr(BitsToShift, One, "rshift", Reverse);
+    BitsToShift->addIncoming(NewVal, Reverse);
+
+    // Shift the bit into the low bits of the result.
+    Instruction *NewRes = 
+      BinaryOperator::createShl(RRes, One, "lshift", Reverse);
+    NewRes = BinaryOperator::createOr(NewRes, Bit, "addbit", Reverse);
+    RRes->addIncoming(NewRes, Reverse);
+    
+    // Terminate loop if we've moved all the bits.
+    ICmpInst *Cond = 
+      new ICmpInst(ICmpInst::ICMP_EQ, Decr, Zero, "cond", Reverse);
+    new BranchInst(RsltBlk, Reverse, Cond, Reverse);
+
+    // Finally, in the result block, select one of the two results with a PHI
+    // node and return the result;
+    CurBB = RsltBlk;
+    PHINode *BitSelect = new PHINode(Val->getType(), "part_select", CurBB);
+    BitSelect->reserveOperandSpace(2);
+    BitSelect->addIncoming(FRes, Compute);
+    BitSelect->addIncoming(NewRes, Reverse);
+    new ReturnInst(BitSelect, CurBB);
+  }
+
+  // Return a call to the implementation function
+  Value *Args[] = {
+    CI->getOperand(1),
+    CI->getOperand(2),
+    CI->getOperand(3)
+  };
+  return new CallInst(F, Args, sizeof(Args)/sizeof(Args[0]), CI->getName(), CI);
+}
+
+/// Convert the llvm.part.set.iX.iY.iZ intrinsic. This intrinsic takes 
+/// four integer arguments (iAny %Value, iAny %Replacement, i32 %Low, i32 %High)
+/// The first two arguments can be any bit width. The result is the same width
+/// as %Value. The operation replaces bits between %Low and %High with the value
+/// in %Replacement. If %Replacement is not the same width, it is truncated or
+/// zero extended as appropriate to fit the bits being replaced. If %Low is
+/// greater than %High then the inverse set of bits are replaced.
+/// @brief Lowering of llvm.bit.part.set intrinsic.
+static Instruction *LowerPartSet(CallInst *CI) {
+  // Make sure we're dealing with a part select intrinsic here
+  Function *F = CI->getCalledFunction();
+  const FunctionType *FT = F->getFunctionType();
+  if (!F->isDeclaration() || !FT->getReturnType()->isInteger() ||
+      FT->getNumParams() != 4 || !FT->getParamType(0)->isInteger() ||
+      !FT->getParamType(1)->isInteger() || !FT->getParamType(2)->isInteger() ||
+      !FT->getParamType(3)->isInteger())
+    return CI;
+
+  // Get the intrinsic implementation function by converting all the . to _
+  // in the intrinsic's function name and then reconstructing the function
+  // declaration.
+  std::string Name(F->getName());
+  for (unsigned i = 4; i < Name.length(); ++i)
+    if (Name[i] == '.')
+      Name[i] = '_';
+  Module* M = F->getParent();
+  F = cast<Function>(M->getOrInsertFunction(Name, FT));
+  F->setLinkage(GlobalValue::WeakLinkage);
+
+  // If we haven't defined the impl function yet, do so now
+  if (F->isDeclaration()) {
+    // Get the arguments for the function.
+    Function::arg_iterator args = F->arg_begin();
+    Value* Val = args++; Val->setName("Val");
+    Value* Rep = args++; Rep->setName("Rep");
+    Value* Lo  = args++; Lo->setName("Lo");
+    Value* Hi  = args++; Hi->setName("Hi");
+
+    // Get some types we need
+    const IntegerType* ValTy = cast<IntegerType>(Val->getType());
+    const IntegerType* RepTy = cast<IntegerType>(Rep->getType());
+    uint32_t ValBits = ValTy->getBitWidth();
+    uint32_t RepBits = RepTy->getBitWidth();
+
+    // Constant Definitions
+    ConstantInt* RepBitWidth = ConstantInt::get(Type::Int32Ty, RepBits);
+    ConstantInt* RepMask = ConstantInt::getAllOnesValue(RepTy);
+    ConstantInt* ValMask = ConstantInt::getAllOnesValue(ValTy);
+    ConstantInt* One = ConstantInt::get(Type::Int32Ty, 1);
+    ConstantInt* ValOne = ConstantInt::get(ValTy, 1);
+    ConstantInt* Zero = ConstantInt::get(Type::Int32Ty, 0);
+    ConstantInt* ValZero = ConstantInt::get(ValTy, 0);
+
+    // Basic blocks we fill in below.
+    BasicBlock* entry = new BasicBlock("entry", F, 0);
+    BasicBlock* large = new BasicBlock("large", F, 0);
+    BasicBlock* small = new BasicBlock("small", F, 0);
+    BasicBlock* reverse = new BasicBlock("reverse", F, 0);
+    BasicBlock* result = new BasicBlock("result", F, 0);
+
+    // BASIC BLOCK: entry
+    // First, get the number of bits that we're placing as an i32
+    ICmpInst* is_forward = 
+      new ICmpInst(ICmpInst::ICMP_ULT, Lo, Hi, "", entry);
+    SelectInst* Hi_pn = new SelectInst(is_forward, Hi, Lo, "", entry);
+    SelectInst* Lo_pn = new SelectInst(is_forward, Lo, Hi, "", entry);
+    BinaryOperator* NumBits = BinaryOperator::createSub(Hi_pn, Lo_pn, "",entry);
+    NumBits = BinaryOperator::createAdd(NumBits, One, "", entry);
+    // Now, convert Lo and Hi to ValTy bit width
+    if (ValBits > 32) {
+      Lo = new ZExtInst(Lo_pn, ValTy, "", entry);
+    } else if (ValBits < 32) {
+      Lo = new TruncInst(Lo_pn, ValTy, "", entry);
+    }
+    // Determine if the replacement bits are larger than the number of bits we
+    // are replacing and deal with it.
+    ICmpInst* is_large = 
+      new ICmpInst(ICmpInst::ICMP_ULT, NumBits, RepBitWidth, "", entry);
+    new BranchInst(large, small, is_large, entry);
+
+    // BASIC BLOCK: large
+    Instruction* MaskBits = 
+      BinaryOperator::createSub(RepBitWidth, NumBits, "", large);
+    MaskBits = CastInst::createIntegerCast(MaskBits, RepMask->getType(), 
+                                           false, "", large);
+    BinaryOperator* Mask1 = 
+      BinaryOperator::createLShr(RepMask, MaskBits, "", large);
+    BinaryOperator* Rep2 = BinaryOperator::createAnd(Mask1, Rep, "", large);
+    new BranchInst(small, large);
+
+    // BASIC BLOCK: small
+    PHINode* Rep3 = new PHINode(RepTy, "", small);
+    Rep3->reserveOperandSpace(2);
+    Rep3->addIncoming(Rep2, large);
+    Rep3->addIncoming(Rep, entry);
+    Value* Rep4 = Rep3;
+    if (ValBits > RepBits)
+      Rep4 = new ZExtInst(Rep3, ValTy, "", small);
+    else if (ValBits < RepBits)
+      Rep4 = new TruncInst(Rep3, ValTy, "", small);
+    new BranchInst(result, reverse, is_forward, small);
+
+    // BASIC BLOCK: reverse (reverses the bits of the replacement)
+    // Set up our loop counter as a PHI so we can decrement on each iteration.
+    // We will loop for the number of bits in the replacement value.
+    PHINode *Count = new PHINode(Type::Int32Ty, "count", reverse);
+    Count->reserveOperandSpace(2);
+    Count->addIncoming(NumBits, small);
+
+    // Get the value that we are shifting bits out of as a PHI because
+    // we'll change this with each iteration.
+    PHINode *BitsToShift   = new PHINode(Val->getType(), "val", reverse);
+    BitsToShift->reserveOperandSpace(2);
+    BitsToShift->addIncoming(Rep4, small);
+
+    // Get the result of the last computation or zero on first iteration
+    PHINode *RRes  = new PHINode(Val->getType(), "rres", reverse);
+    RRes->reserveOperandSpace(2);
+    RRes->addIncoming(ValZero, small);
+
+    // Decrement the loop counter by one
+    Instruction *Decr = BinaryOperator::createSub(Count, One, "", reverse);
+    Count->addIncoming(Decr, reverse);
+
+    // Get the bit that we want to move into the result
+    Value *Bit = BinaryOperator::createAnd(BitsToShift, ValOne, "", reverse);
+
+    // Compute the new value of the bits to shift for the next iteration.
+    Value *NewVal = BinaryOperator::createLShr(BitsToShift, ValOne,"", reverse);
+    BitsToShift->addIncoming(NewVal, reverse);
+
+    // Shift the bit we extracted into the low bit of the result.
+    Instruction *NewRes = BinaryOperator::createShl(RRes, ValOne, "", reverse);
+    NewRes = BinaryOperator::createOr(NewRes, Bit, "", reverse);
+    RRes->addIncoming(NewRes, reverse);
+    
+    // Terminate loop if we've moved all the bits.
+    ICmpInst *Cond = new ICmpInst(ICmpInst::ICMP_EQ, Decr, Zero, "", reverse);
+    new BranchInst(result, reverse, Cond, reverse);
+
+    // BASIC BLOCK: result
+    PHINode *Rplcmnt  = new PHINode(Val->getType(), "", result);
+    Rplcmnt->reserveOperandSpace(2);
+    Rplcmnt->addIncoming(NewRes, reverse);
+    Rplcmnt->addIncoming(Rep4, small);
+    Value* t0   = CastInst::createIntegerCast(NumBits,ValTy,false,"",result);
+    Value* t1   = BinaryOperator::createShl(ValMask, Lo, "", result);
+    Value* t2   = BinaryOperator::createNot(t1, "", result);
+    Value* t3   = BinaryOperator::createShl(t1, t0, "", result);
+    Value* t4   = BinaryOperator::createOr(t2, t3, "", result);
+    Value* t5   = BinaryOperator::createAnd(t4, Val, "", result);
+    Value* t6   = BinaryOperator::createShl(Rplcmnt, Lo, "", result);
+    Value* Rslt = BinaryOperator::createOr(t5, t6, "part_set", result);
+    new ReturnInst(Rslt, result);
+  }
+
+  // Return a call to the implementation function
+  Value *Args[] = {
+    CI->getOperand(1),
+    CI->getOperand(2),
+    CI->getOperand(3),
+    CI->getOperand(4)
+  };
+  return new CallInst(F, Args, sizeof(Args)/sizeof(Args[0]), CI->getName(), CI);
+}
+
+
+void IntrinsicLowering::LowerIntrinsicCall(CallInst *CI) {
+  Function *Callee = CI->getCalledFunction();
+  assert(Callee && "Cannot lower an indirect call!");
+
+  switch (Callee->getIntrinsicID()) {
+  case Intrinsic::not_intrinsic:
+    cerr << "Cannot lower a call to a non-intrinsic function '"
+         << Callee->getName() << "'!\n";
+    abort();
+  default:
+    cerr << "Error: Code generator does not support intrinsic function '"
+         << Callee->getName() << "'!\n";
+    abort();
+
+    // The setjmp/longjmp intrinsics should only exist in the code if it was
+    // never optimized (ie, right out of the CFE), or if it has been hacked on
+    // by the lowerinvoke pass.  In both cases, the right thing to do is to
+    // convert the call to an explicit setjmp or longjmp call.
+  case Intrinsic::setjmp: {
+    static Constant *SetjmpFCache = 0;
+    Value *V = ReplaceCallWith("setjmp", CI, CI->op_begin()+1, CI->op_end(),
+                               Type::Int32Ty, SetjmpFCache);
+    if (CI->getType() != Type::VoidTy)
+      CI->replaceAllUsesWith(V);
+    break;
+  }
+  case Intrinsic::sigsetjmp:
+     if (CI->getType() != Type::VoidTy)
+       CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
+     break;
+
+  case Intrinsic::longjmp: {
+    static Constant *LongjmpFCache = 0;
+    ReplaceCallWith("longjmp", CI, CI->op_begin()+1, CI->op_end(),
+                    Type::VoidTy, LongjmpFCache);
+    break;
+  }
+
+  case Intrinsic::siglongjmp: {
+    // Insert the call to abort
+    static Constant *AbortFCache = 0;
+    ReplaceCallWith("abort", CI, CI->op_end(), CI->op_end(), 
+                    Type::VoidTy, AbortFCache);
+    break;
+  }
+  case Intrinsic::ctpop:
+    CI->replaceAllUsesWith(LowerCTPOP(CI->getOperand(1), CI));
+    break;
+
+  case Intrinsic::bswap:
+    CI->replaceAllUsesWith(LowerBSWAP(CI->getOperand(1), CI));
+    break;
+    
+  case Intrinsic::ctlz:
+    CI->replaceAllUsesWith(LowerCTLZ(CI->getOperand(1), CI));
+    break;
+
+  case Intrinsic::cttz: {
+    // cttz(x) -> ctpop(~X & (X-1))
+    Value *Src = CI->getOperand(1);
+    Value *NotSrc = BinaryOperator::createNot(Src, Src->getName()+".not", CI);
+    Value *SrcM1  = ConstantInt::get(Src->getType(), 1);
+    SrcM1 = BinaryOperator::createSub(Src, SrcM1, "", CI);
+    Src = LowerCTPOP(BinaryOperator::createAnd(NotSrc, SrcM1, "", CI), CI);
+    CI->replaceAllUsesWith(Src);
+    break;
+  }
+
+  case Intrinsic::part_select:
+    CI->replaceAllUsesWith(LowerPartSelect(CI));
+    break;
+
+  case Intrinsic::part_set:
+    CI->replaceAllUsesWith(LowerPartSet(CI));
+    break;
+
+  case Intrinsic::stacksave:
+  case Intrinsic::stackrestore: {
+    static bool Warned = false;
+    if (!Warned)
+      cerr << "WARNING: this target does not support the llvm.stack"
+           << (Callee->getIntrinsicID() == Intrinsic::stacksave ?
+               "save" : "restore") << " intrinsic.\n";
+    Warned = true;
+    if (Callee->getIntrinsicID() == Intrinsic::stacksave)
+      CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
+    break;
+  }
+    
+  case Intrinsic::returnaddress:
+  case Intrinsic::frameaddress:
+    cerr << "WARNING: this target does not support the llvm."
+         << (Callee->getIntrinsicID() == Intrinsic::returnaddress ?
+             "return" : "frame") << "address intrinsic.\n";
+    CI->replaceAllUsesWith(ConstantPointerNull::get(
+                                            cast<PointerType>(CI->getType())));
+    break;
+
+  case Intrinsic::prefetch:
+    break;    // Simply strip out prefetches on unsupported architectures
+
+  case Intrinsic::pcmarker:
+    break;    // Simply strip out pcmarker on unsupported architectures
+  case Intrinsic::readcyclecounter: {
+    cerr << "WARNING: this target does not support the llvm.readcyclecoun"
+         << "ter intrinsic.  It is being lowered to a constant 0\n";
+    CI->replaceAllUsesWith(ConstantInt::get(Type::Int64Ty, 0));
+    break;
+  }
+
+  case Intrinsic::dbg_stoppoint:
+  case Intrinsic::dbg_region_start:
+  case Intrinsic::dbg_region_end:
+  case Intrinsic::dbg_func_start:
+  case Intrinsic::dbg_declare:
+    break;    // Simply strip out debugging intrinsics
+
+  case Intrinsic::eh_exception:
+  case Intrinsic::eh_selector:
+    CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
+    break;
+
+  case Intrinsic::eh_typeid_for:
+    // Return something different to eh_selector.
+    CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
+    break;
+
+  case Intrinsic::var_annotation:
+    break;   // Strip out annotate intrinsic
+    
+  case Intrinsic::memcpy_i32:
+  case Intrinsic::memcpy_i64: {
+    static Constant *MemcpyFCache = 0;
+    Value *Size = CI->getOperand(3);
+    const Type *IntPtr = TD.getIntPtrType();
+    if (Size->getType()->getPrimitiveSizeInBits() <
+        IntPtr->getPrimitiveSizeInBits())
+      Size = new ZExtInst(Size, IntPtr, "", CI);
+    else if (Size->getType()->getPrimitiveSizeInBits() >
+             IntPtr->getPrimitiveSizeInBits())
+      Size = new TruncInst(Size, IntPtr, "", CI);
+    Value *Ops[3];
+    Ops[0] = CI->getOperand(1);
+    Ops[1] = CI->getOperand(2);
+    Ops[2] = Size;
+    ReplaceCallWith("memcpy", CI, Ops, Ops+3, CI->getOperand(1)->getType(),
+                    MemcpyFCache);
+    break;
+  }
+  case Intrinsic::memmove_i32: 
+  case Intrinsic::memmove_i64: {
+    static Constant *MemmoveFCache = 0;
+    Value *Size = CI->getOperand(3);
+    const Type *IntPtr = TD.getIntPtrType();
+    if (Size->getType()->getPrimitiveSizeInBits() <
+        IntPtr->getPrimitiveSizeInBits())
+      Size = new ZExtInst(Size, IntPtr, "", CI);
+    else if (Size->getType()->getPrimitiveSizeInBits() >
+             IntPtr->getPrimitiveSizeInBits())
+      Size = new TruncInst(Size, IntPtr, "", CI);
+    Value *Ops[3];
+    Ops[0] = CI->getOperand(1);
+    Ops[1] = CI->getOperand(2);
+    Ops[2] = Size;
+    ReplaceCallWith("memmove", CI, Ops, Ops+3, CI->getOperand(1)->getType(),
+                    MemmoveFCache);
+    break;
+  }
+  case Intrinsic::memset_i32:
+  case Intrinsic::memset_i64: {
+    static Constant *MemsetFCache = 0;
+    Value *Size = CI->getOperand(3);
+    const Type *IntPtr = TD.getIntPtrType();
+    if (Size->getType()->getPrimitiveSizeInBits() <
+        IntPtr->getPrimitiveSizeInBits())
+      Size = new ZExtInst(Size, IntPtr, "", CI);
+    else if (Size->getType()->getPrimitiveSizeInBits() >
+             IntPtr->getPrimitiveSizeInBits())
+      Size = new TruncInst(Size, IntPtr, "", CI);
+    Value *Ops[3];
+    Ops[0] = CI->getOperand(1);
+    // Extend the amount to i32.
+    Ops[1] = new ZExtInst(CI->getOperand(2), Type::Int32Ty, "", CI);
+    Ops[2] = Size;
+    ReplaceCallWith("memset", CI, Ops, Ops+3, CI->getOperand(1)->getType(),
+                    MemsetFCache);
+    break;
+  }
+  case Intrinsic::sqrt_f32: {
+    static Constant *sqrtfFCache = 0;
+    ReplaceCallWith("sqrtf", CI, CI->op_begin()+1, CI->op_end(),
+                    Type::FloatTy, sqrtfFCache);
+    break;
+  }
+  case Intrinsic::sqrt_f64: {
+    static Constant *sqrtFCache = 0;
+    ReplaceCallWith("sqrt", CI, CI->op_begin()+1, CI->op_end(),
+                    Type::DoubleTy, sqrtFCache);
+    break;
+  }
+  }
+
+  assert(CI->use_empty() &&
+         "Lowering should have eliminated any uses of the intrinsic call!");
+  CI->eraseFromParent();
+}