diff --git a/llvm/lib/IR/Instructions.cpp b/llvm/lib/IR/Instructions.cpp
index 37b6782..8a6b77b 100644
--- a/llvm/lib/IR/Instructions.cpp
+++ b/llvm/lib/IR/Instructions.cpp
@@ -2095,7 +2095,9 @@
     case Instruction::SIToFP:
     case Instruction::FPToUI:
     case Instruction::FPToSI:
-      return false; // These always modify bits
+    case Instruction::AddrSpaceCast:
+      // TODO: Target informations may give a more accurate answer here.
+      return false;
     case Instruction::BitCast:
       return true;  // BitCast never modifies bits.
     case Instruction::PtrToInt:
@@ -2137,44 +2139,46 @@
   // ZEXT          <       Integral   Unsigned     Integer      Any
   // SEXT          <       Integral    Signed      Integer      Any
   // FPTOUI       n/a      FloatPt      n/a        Integral   Unsigned
-  // FPTOSI       n/a      FloatPt      n/a        Integral    Signed 
-  // UITOFP       n/a      Integral   Unsigned     FloatPt      n/a   
-  // SITOFP       n/a      Integral    Signed      FloatPt      n/a   
-  // FPTRUNC       >       FloatPt      n/a        FloatPt      n/a   
-  // FPEXT         <       FloatPt      n/a        FloatPt      n/a   
+  // FPTOSI       n/a      FloatPt      n/a        Integral    Signed
+  // UITOFP       n/a      Integral   Unsigned     FloatPt      n/a
+  // SITOFP       n/a      Integral    Signed      FloatPt      n/a
+  // FPTRUNC       >       FloatPt      n/a        FloatPt      n/a
+  // FPEXT         <       FloatPt      n/a        FloatPt      n/a
   // PTRTOINT     n/a      Pointer      n/a        Integral   Unsigned
   // INTTOPTR     n/a      Integral   Unsigned     Pointer      n/a
-  // BITCAST       =       FirstClass   n/a       FirstClass    n/a   
+  // BITCAST       =       FirstClass   n/a       FirstClass    n/a
+  // ADDRSPCST    n/a      Pointer      n/a        Pointer      n/a
   //
   // NOTE: some transforms are safe, but we consider them to be non-profitable.
   // For example, we could merge "fptoui double to i32" + "zext i32 to i64",
   // into "fptoui double to i64", but this loses information about the range
-  // of the produced value (we no longer know the top-part is all zeros). 
+  // of the produced value (we no longer know the top-part is all zeros).
   // Further this conversion is often much more expensive for typical hardware,
-  // and causes issues when building libgcc.  We disallow fptosi+sext for the 
+  // and causes issues when building libgcc.  We disallow fptosi+sext for the
   // same reason.
-  const unsigned numCastOps = 
+  const unsigned numCastOps =
     Instruction::CastOpsEnd - Instruction::CastOpsBegin;
   static const uint8_t CastResults[numCastOps][numCastOps] = {
-    // T        F  F  U  S  F  F  P  I  B   -+
-    // R  Z  S  P  P  I  I  T  P  2  N  T    |
-    // U  E  E  2  2  2  2  R  E  I  T  C    +- secondOp
-    // N  X  X  U  S  F  F  N  X  N  2  V    |
-    // C  T  T  I  I  P  P  C  T  T  P  T   -+
-    {  1, 0, 0,99,99, 0, 0,99,99,99, 0, 3 }, // Trunc      -+
-    {  8, 1, 9,99,99, 2, 0,99,99,99, 2, 3 }, // ZExt        |
-    {  8, 0, 1,99,99, 0, 2,99,99,99, 0, 3 }, // SExt        |
-    {  0, 0, 0,99,99, 0, 0,99,99,99, 0, 3 }, // FPToUI      |
-    {  0, 0, 0,99,99, 0, 0,99,99,99, 0, 3 }, // FPToSI      |
-    { 99,99,99, 0, 0,99,99, 0, 0,99,99, 4 }, // UIToFP      +- firstOp
-    { 99,99,99, 0, 0,99,99, 0, 0,99,99, 4 }, // SIToFP      |
-    { 99,99,99, 0, 0,99,99, 1, 0,99,99, 4 }, // FPTrunc     |
-    { 99,99,99, 2, 2,99,99,10, 2,99,99, 4 }, // FPExt       |
-    {  1, 0, 0,99,99, 0, 0,99,99,99, 7, 3 }, // PtrToInt    |
-    { 99,99,99,99,99,99,99,99,99,13,99,12 }, // IntToPtr    |
-    {  5, 5, 5, 6, 6, 5, 5, 6, 6,11, 5, 1 }, // BitCast    -+
+    // T        F  F  U  S  F  F  P  I  B  A  -+
+    // R  Z  S  P  P  I  I  T  P  2  N  T  S   |
+    // U  E  E  2  2  2  2  R  E  I  T  C  C   +- secondOp
+    // N  X  X  U  S  F  F  N  X  N  2  V  V   |
+    // C  T  T  I  I  P  P  C  T  T  P  T  T  -+
+    {  1, 0, 0,99,99, 0, 0,99,99,99, 0, 3, 0}, // Trunc         -+
+    {  8, 1, 9,99,99, 2, 0,99,99,99, 2, 3, 0}, // ZExt           |
+    {  8, 0, 1,99,99, 0, 2,99,99,99, 0, 3, 0}, // SExt           |
+    {  0, 0, 0,99,99, 0, 0,99,99,99, 0, 3, 0}, // FPToUI         |
+    {  0, 0, 0,99,99, 0, 0,99,99,99, 0, 3, 0}, // FPToSI         |
+    { 99,99,99, 0, 0,99,99, 0, 0,99,99, 4, 0}, // UIToFP         +- firstOp
+    { 99,99,99, 0, 0,99,99, 0, 0,99,99, 4, 0}, // SIToFP         |
+    { 99,99,99, 0, 0,99,99, 1, 0,99,99, 4, 0}, // FPTrunc        |
+    { 99,99,99, 2, 2,99,99,10, 2,99,99, 4, 0}, // FPExt          |
+    {  1, 0, 0,99,99, 0, 0,99,99,99, 7, 3, 0}, // PtrToInt       |
+    { 99,99,99,99,99,99,99,99,99,11,99,15, 0}, // IntToPtr       |
+    {  5, 5, 5, 6, 6, 5, 5, 6, 6,16, 5, 1,14}, // BitCast        |
+    {  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,13,12}, // AddrSpaceCast -+
   };
-  
+
   // If either of the casts are a bitcast from scalar to vector, disallow the
   // merging. However, bitcast of A->B->A are allowed.
   bool isFirstBitcast  = (firstOp == Instruction::BitCast);
@@ -2191,47 +2195,50 @@
                             [secondOp-Instruction::CastOpsBegin];
   switch (ElimCase) {
     case 0: 
-      // categorically disallowed
+      // Categorically disallowed.
       return 0;
     case 1: 
-      // allowed, use first cast's opcode
+      // Allowed, use first cast's opcode.
       return firstOp;
     case 2: 
-      // allowed, use second cast's opcode
+      // Allowed, use second cast's opcode.
       return secondOp;
     case 3: 
-      // no-op cast in second op implies firstOp as long as the DestTy 
+      // No-op cast in second op implies firstOp as long as the DestTy
       // is integer and we are not converting between a vector and a
       // non vector type.
       if (!SrcTy->isVectorTy() && DstTy->isIntegerTy())
         return firstOp;
       return 0;
     case 4:
-      // no-op cast in second op implies firstOp as long as the DestTy
+      // No-op cast in second op implies firstOp as long as the DestTy
       // is floating point.
       if (DstTy->isFloatingPointTy())
         return firstOp;
       return 0;
     case 5: 
-      // no-op cast in first op implies secondOp as long as the SrcTy
+      // No-op cast in first op implies secondOp as long as the SrcTy
       // is an integer.
       if (SrcTy->isIntegerTy())
         return secondOp;
       return 0;
     case 6:
-      // no-op cast in first op implies secondOp as long as the SrcTy
+      // No-op cast in first op implies secondOp as long as the SrcTy
       // is a floating point.
       if (SrcTy->isFloatingPointTy())
         return secondOp;
       return 0;
     case 7: {
+      // Cannot simplify if address spaces are different!
+      if (SrcTy->getPointerAddressSpace() != DstTy->getPointerAddressSpace())
+        return 0;
+
       unsigned MidSize = MidTy->getScalarSizeInBits();
-      // Check the address spaces first. If we know they are in the same address
-      // space, the pointer sizes must be the same so we can still fold this
-      // without knowing the actual sizes as long we know that the intermediate
-      // pointer is the largest possible pointer size.
-      if (MidSize == 64 &&
-          SrcTy->getPointerAddressSpace() == DstTy->getPointerAddressSpace())
+      // We can still fold this without knowing the actual sizes as long we
+      // know that the intermediate pointer is the largest possible
+      // pointer size.
+      // FIXME: Is this always true?
+      if (MidSize == 64)
         return Instruction::BitCast;
 
       // ptrtoint, inttoptr -> bitcast (ptr -> ptr) if int size is >= ptr size.
@@ -2254,7 +2261,8 @@
         return firstOp;
       return secondOp;
     }
-    case 9: // zext, sext -> zext, because sext can't sign extend after zext
+    case 9:
+      // zext, sext -> zext, because sext can't sign extend after zext
       return Instruction::ZExt;
     case 10:
       // fpext followed by ftrunc is allowed if the bit size returned to is
@@ -2263,46 +2271,6 @@
         return Instruction::BitCast;
       return 0; // If the types are not the same we can't eliminate it.
     case 11: {
-      // bitcast followed by ptrtoint is allowed as long as the bitcast is a
-      // pointer to pointer cast, and the pointers are the same size.
-      PointerType *SrcPtrTy = dyn_cast<PointerType>(SrcTy);
-      PointerType *MidPtrTy = dyn_cast<PointerType>(MidTy);
-      if (!SrcPtrTy || !MidPtrTy)
-        return 0;
-
-      // If the address spaces are the same, we know they are the same size
-      // without size information
-      if (SrcPtrTy->getAddressSpace() == MidPtrTy->getAddressSpace())
-        return secondOp;
-
-      if (!SrcIntPtrTy || !MidIntPtrTy)
-        return 0;
-
-      if (SrcIntPtrTy->getScalarSizeInBits() ==
-          MidIntPtrTy->getScalarSizeInBits())
-        return secondOp;
-
-      return 0;
-    }
-    case 12: {
-      // inttoptr, bitcast -> inttoptr if bitcast is a ptr to ptr cast
-      // and the ptrs are to address spaces of the same size
-      PointerType *MidPtrTy = dyn_cast<PointerType>(MidTy);
-      PointerType *DstPtrTy = dyn_cast<PointerType>(DstTy);
-      if (!MidPtrTy || !DstPtrTy)
-        return 0;
-
-      if (MidPtrTy->getAddressSpace() == DstPtrTy->getAddressSpace())
-        return firstOp;
-
-      if (MidIntPtrTy &&
-          DstIntPtrTy &&
-          MidIntPtrTy->getScalarSizeInBits() ==
-          DstIntPtrTy->getScalarSizeInBits())
-        return firstOp;
-      return 0;
-    }
-    case 13: {
       // inttoptr, ptrtoint -> bitcast if SrcSize<=PtrSize and SrcSize==DstSize
       if (!MidIntPtrTy)
         return 0;
@@ -2313,8 +2281,65 @@
         return Instruction::BitCast;
       return 0;
     }
+    case 12: {
+      // addrspacecast, addrspacecast -> bitcast,       if SrcAS == DstAS
+      // addrspacecast, addrspacecast -> addrspacecast, if SrcAS != DstAS
+      if (SrcTy->getPointerAddressSpace() != DstTy->getPointerAddressSpace())
+        return Instruction::AddrSpaceCast;
+      return Instruction::BitCast;
+    }
+    case 13:
+      // FIXME: this state can be merged with (1), but the following assert
+      // is useful to check the correcteness of the sequence due to semantic
+      // change of bitcast.
+      assert(
+        SrcTy->isPtrOrPtrVectorTy() &&
+        MidTy->isPtrOrPtrVectorTy() &&
+        DstTy->isPtrOrPtrVectorTy() &&
+        SrcTy->getPointerAddressSpace() != MidTy->getPointerAddressSpace() &&
+        MidTy->getPointerAddressSpace() == DstTy->getPointerAddressSpace() &&
+        "Illegal addrspacecast, bitcast sequence!");
+      // Allowed, use first cast's opcode
+      return firstOp;
+    case 14:
+      // FIXME: this state can be merged with (2), but the following assert
+      // is useful to check the correcteness of the sequence due to semantic
+      // change of bitcast.
+      assert(
+        SrcTy->isPtrOrPtrVectorTy() &&
+        MidTy->isPtrOrPtrVectorTy() &&
+        DstTy->isPtrOrPtrVectorTy() &&
+        SrcTy->getPointerAddressSpace() == MidTy->getPointerAddressSpace() &&
+        MidTy->getPointerAddressSpace() != DstTy->getPointerAddressSpace() &&
+        "Illegal bitcast, addrspacecast sequence!");
+      // Allowed, use second cast's opcode
+      return secondOp;
+    case 15:
+      // FIXME: this state can be merged with (1), but the following assert
+      // is useful to check the correcteness of the sequence due to semantic
+      // change of bitcast.
+      assert(
+        SrcTy->isIntOrIntVectorTy() &&
+        MidTy->isPtrOrPtrVectorTy() &&
+        DstTy->isPtrOrPtrVectorTy() &&
+        MidTy->getPointerAddressSpace() == DstTy->getPointerAddressSpace() &&
+        "Illegal inttoptr, bitcast sequence!");
+      // Allowed, use first cast's opcode
+      return firstOp;
+    case 16:
+      // FIXME: this state can be merged with (2), but the following assert
+      // is useful to check the correcteness of the sequence due to semantic
+      // change of bitcast.
+      assert(
+        SrcTy->isPtrOrPtrVectorTy() &&
+        MidTy->isPtrOrPtrVectorTy() &&
+        DstTy->isIntOrIntVectorTy() &&
+        SrcTy->getPointerAddressSpace() == MidTy->getPointerAddressSpace() &&
+        "Illegal bitcast, ptrtoint sequence!");
+      // Allowed, use second cast's opcode
+      return secondOp;
     case 99: 
-      // cast combination can't happen (error in input). This is for all cases
+      // Cast combination can't happen (error in input). This is for all cases
       // where the MidTy is not the same for the two cast instructions.
       llvm_unreachable("Invalid Cast Combination");
     default:
@@ -2327,19 +2352,20 @@
   assert(castIsValid(op, S, Ty) && "Invalid cast!");
   // Construct and return the appropriate CastInst subclass
   switch (op) {
-    case Trunc:    return new TruncInst    (S, Ty, Name, InsertBefore);
-    case ZExt:     return new ZExtInst     (S, Ty, Name, InsertBefore);
-    case SExt:     return new SExtInst     (S, Ty, Name, InsertBefore);
-    case FPTrunc:  return new FPTruncInst  (S, Ty, Name, InsertBefore);
-    case FPExt:    return new FPExtInst    (S, Ty, Name, InsertBefore);
-    case UIToFP:   return new UIToFPInst   (S, Ty, Name, InsertBefore);
-    case SIToFP:   return new SIToFPInst   (S, Ty, Name, InsertBefore);
-    case FPToUI:   return new FPToUIInst   (S, Ty, Name, InsertBefore);
-    case FPToSI:   return new FPToSIInst   (S, Ty, Name, InsertBefore);
-    case PtrToInt: return new PtrToIntInst (S, Ty, Name, InsertBefore);
-    case IntToPtr: return new IntToPtrInst (S, Ty, Name, InsertBefore);
-    case BitCast:  return new BitCastInst  (S, Ty, Name, InsertBefore);
-    default: llvm_unreachable("Invalid opcode provided");
+  case Trunc:         return new TruncInst         (S, Ty, Name, InsertBefore);
+  case ZExt:          return new ZExtInst          (S, Ty, Name, InsertBefore);
+  case SExt:          return new SExtInst          (S, Ty, Name, InsertBefore);
+  case FPTrunc:       return new FPTruncInst       (S, Ty, Name, InsertBefore);
+  case FPExt:         return new FPExtInst         (S, Ty, Name, InsertBefore);
+  case UIToFP:        return new UIToFPInst        (S, Ty, Name, InsertBefore);
+  case SIToFP:        return new SIToFPInst        (S, Ty, Name, InsertBefore);
+  case FPToUI:        return new FPToUIInst        (S, Ty, Name, InsertBefore);
+  case FPToSI:        return new FPToSIInst        (S, Ty, Name, InsertBefore);
+  case PtrToInt:      return new PtrToIntInst      (S, Ty, Name, InsertBefore);
+  case IntToPtr:      return new IntToPtrInst      (S, Ty, Name, InsertBefore);
+  case BitCast:       return new BitCastInst       (S, Ty, Name, InsertBefore);
+  case AddrSpaceCast: return new AddrSpaceCastInst (S, Ty, Name, InsertBefore);
+  default: llvm_unreachable("Invalid opcode provided");
   }
 }
 
@@ -2348,19 +2374,20 @@
   assert(castIsValid(op, S, Ty) && "Invalid cast!");
   // Construct and return the appropriate CastInst subclass
   switch (op) {
-    case Trunc:    return new TruncInst    (S, Ty, Name, InsertAtEnd);
-    case ZExt:     return new ZExtInst     (S, Ty, Name, InsertAtEnd);
-    case SExt:     return new SExtInst     (S, Ty, Name, InsertAtEnd);
-    case FPTrunc:  return new FPTruncInst  (S, Ty, Name, InsertAtEnd);
-    case FPExt:    return new FPExtInst    (S, Ty, Name, InsertAtEnd);
-    case UIToFP:   return new UIToFPInst   (S, Ty, Name, InsertAtEnd);
-    case SIToFP:   return new SIToFPInst   (S, Ty, Name, InsertAtEnd);
-    case FPToUI:   return new FPToUIInst   (S, Ty, Name, InsertAtEnd);
-    case FPToSI:   return new FPToSIInst   (S, Ty, Name, InsertAtEnd);
-    case PtrToInt: return new PtrToIntInst (S, Ty, Name, InsertAtEnd);
-    case IntToPtr: return new IntToPtrInst (S, Ty, Name, InsertAtEnd);
-    case BitCast:  return new BitCastInst  (S, Ty, Name, InsertAtEnd);
-    default: llvm_unreachable("Invalid opcode provided");
+  case Trunc:         return new TruncInst         (S, Ty, Name, InsertAtEnd);
+  case ZExt:          return new ZExtInst          (S, Ty, Name, InsertAtEnd);
+  case SExt:          return new SExtInst          (S, Ty, Name, InsertAtEnd);
+  case FPTrunc:       return new FPTruncInst       (S, Ty, Name, InsertAtEnd);
+  case FPExt:         return new FPExtInst         (S, Ty, Name, InsertAtEnd);
+  case UIToFP:        return new UIToFPInst        (S, Ty, Name, InsertAtEnd);
+  case SIToFP:        return new SIToFPInst        (S, Ty, Name, InsertAtEnd);
+  case FPToUI:        return new FPToUIInst        (S, Ty, Name, InsertAtEnd);
+  case FPToSI:        return new FPToSIInst        (S, Ty, Name, InsertAtEnd);
+  case PtrToInt:      return new PtrToIntInst      (S, Ty, Name, InsertAtEnd);
+  case IntToPtr:      return new IntToPtrInst      (S, Ty, Name, InsertAtEnd);
+  case BitCast:       return new BitCastInst       (S, Ty, Name, InsertAtEnd);
+  case AddrSpaceCast: return new AddrSpaceCastInst (S, Ty, Name, InsertAtEnd);
+  default: llvm_unreachable("Invalid opcode provided");
   }
 }
 
@@ -2425,6 +2452,11 @@
 
   if (Ty->isIntOrIntVectorTy())
     return Create(Instruction::PtrToInt, S, Ty, Name, InsertAtEnd);
+
+  Type *STy = S->getType();
+  if (STy->getPointerAddressSpace() != Ty->getPointerAddressSpace())
+    return Create(Instruction::AddrSpaceCast, S, Ty, Name, InsertAtEnd);
+
   return Create(Instruction::BitCast, S, Ty, Name, InsertAtEnd);
 }
 
@@ -2442,6 +2474,11 @@
 
   if (Ty->isIntOrIntVectorTy())
     return Create(Instruction::PtrToInt, S, Ty, Name, InsertBefore);
+
+  Type *STy = S->getType();
+  if (STy->getPointerAddressSpace() != Ty->getPointerAddressSpace())
+    return Create(Instruction::AddrSpaceCast, S, Ty, Name, InsertBefore);
+
   return Create(Instruction::BitCast, S, Ty, Name, InsertBefore);
 }
 
@@ -2687,7 +2724,8 @@
     return BitCast;
   } else if (DestTy->isPointerTy()) {
     if (SrcTy->isPointerTy()) {
-      // TODO: Address space pointer sizes may not match
+      if (DestTy->getPointerAddressSpace() != SrcTy->getPointerAddressSpace())
+        return AddrSpaceCast;
       return BitCast;                               // ptr -> ptr
     } else if (SrcTy->isIntegerTy()) {
       return IntToPtr;                              // int -> ptr
@@ -2782,13 +2820,27 @@
   case Instruction::BitCast:
     // BitCast implies a no-op cast of type only. No bits change.
     // However, you can't cast pointers to anything but pointers.
-    if (SrcTy->isPointerTy() != DstTy->isPointerTy())
+    if (SrcTy->isPtrOrPtrVectorTy() != DstTy->isPtrOrPtrVectorTy())
       return false;
 
-    // Now we know we're not dealing with a pointer/non-pointer mismatch. In all
-    // these cases, the cast is okay if the source and destination bit widths
-    // are identical.
-    return SrcTy->getPrimitiveSizeInBits() == DstTy->getPrimitiveSizeInBits();
+    // For non pointer cases, the cast is okay if the source and destination bit
+    // widths are identical.
+    if (!SrcTy->isPtrOrPtrVectorTy())
+      return SrcTy->getPrimitiveSizeInBits() == DstTy->getPrimitiveSizeInBits();
+
+    // If both are pointers then the address spaces must match and vector of
+    // pointers must have the same number of elements.
+    return SrcTy->getPointerAddressSpace() == DstTy->getPointerAddressSpace() &&
+           SrcTy->isVectorTy() == DstTy->isVectorTy() &&
+           (!SrcTy->isVectorTy() ||
+            SrcTy->getVectorNumElements() == SrcTy->getVectorNumElements());
+
+  case Instruction::AddrSpaceCast:
+    return SrcTy->isPtrOrPtrVectorTy() && DstTy->isPtrOrPtrVectorTy() &&
+           SrcTy->getPointerAddressSpace() != DstTy->getPointerAddressSpace() &&
+           SrcTy->isVectorTy() == DstTy->isVectorTy() &&
+           (!SrcTy->isVectorTy() ||
+            SrcTy->getVectorNumElements() == SrcTy->getVectorNumElements());
   }
 }
 
@@ -2935,6 +2987,18 @@
   assert(castIsValid(getOpcode(), S, Ty) && "Illegal BitCast");
 }
 
+AddrSpaceCastInst::AddrSpaceCastInst(
+  Value *S, Type *Ty, const Twine &Name, Instruction *InsertBefore
+) : CastInst(Ty, AddrSpaceCast, S, Name, InsertBefore) {
+  assert(castIsValid(getOpcode(), S, Ty) && "Illegal AddrSpaceCast");
+}
+
+AddrSpaceCastInst::AddrSpaceCastInst(
+  Value *S, Type *Ty, const Twine &Name, BasicBlock *InsertAtEnd
+) : CastInst(Ty, AddrSpaceCast, S, Name, InsertAtEnd) {
+  assert(castIsValid(getOpcode(), S, Ty) && "Illegal AddrSpaceCast");
+}
+
 //===----------------------------------------------------------------------===//
 //                               CmpInst Classes
 //===----------------------------------------------------------------------===//
@@ -3553,6 +3617,10 @@
   return new BitCastInst(getOperand(0), getType());
 }
 
+AddrSpaceCastInst *AddrSpaceCastInst::clone_impl() const {
+  return new AddrSpaceCastInst(getOperand(0), getType());
+}
+
 CallInst *CallInst::clone_impl() const {
   return  new(getNumOperands()) CallInst(*this);
 }