Respect address space sizes in isEliminableCastPair.

This avoids constant folding bitcast/ptrtoint/inttoptr combinations
that have illegal bitcasts between differently sized address spaces.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187455 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 52 insertions, 14 deletions

diff --git a/lib/IR/ConstantFold.cpp b/lib/IR/ConstantFold.cpp
index da9762f..8c5a983 100644
--- a/lib/IR/ConstantFold.cpp
+++ b/lib/IR/ConstantFold.cpp
@@ -75,7 +75,7 @@ static unsigned
 foldConstantCastPair(
   unsigned opc,          ///< opcode of the second cast constant expression
   ConstantExpr *Op,      ///< the first cast constant expression
-  Type *DstTy      ///< desintation type of the first cast
+  Type *DstTy            ///< destination type of the first cast
 ) {
   assert(Op && Op->isCast() && "Can't fold cast of cast without a cast!");
   assert(DstTy && DstTy->isFirstClassType() && "Invalid cast destination type");
@@ -87,13 +87,14 @@ foldConstantCastPair(
   Instruction::CastOps firstOp = Instruction::CastOps(Op->getOpcode());
   Instruction::CastOps secondOp = Instruction::CastOps(opc);
 
-  // Assume that pointers are never more than 64 bits wide.
+  // Assume that pointers are never more than 64 bits wide, and only use this
+  // for the middle type. Otherwise we could end up folding away illegal
+  // bitcasts between address spaces with different sizes.
   IntegerType *FakeIntPtrTy = Type::getInt64Ty(DstTy->getContext());
 
   // Let CastInst::isEliminableCastPair do the heavy lifting.
   return CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, DstTy,
-                                        FakeIntPtrTy, FakeIntPtrTy,
-                                        FakeIntPtrTy);
+                                        0, FakeIntPtrTy, 0);
 }
 
 static Constant *FoldBitCast(Constant *V, Type *DestTy) {
diff --git a/lib/IR/Instructions.cpp b/lib/IR/Instructions.cpp
index 665fe66..49a9e8c 100644
--- a/lib/IR/Instructions.cpp
+++ b/lib/IR/Instructions.cpp
@@ -2224,12 +2224,20 @@ unsigned CastInst::isEliminableCastPair(
       if (SrcTy->isFloatingPointTy())
         return secondOp;
       return 0;
-    case 7: { 
-      // ptrtoint, inttoptr -> bitcast (ptr -> ptr) if int size is >= ptr size
+    case 7: {
+      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())
+        return Instruction::BitCast;
+
+      // ptrtoint, inttoptr -> bitcast (ptr -> ptr) if int size is >= ptr size.
       if (!SrcIntPtrTy || DstIntPtrTy != SrcIntPtrTy)
         return 0;
       unsigned PtrSize = SrcIntPtrTy->getScalarSizeInBits();
-      unsigned MidSize = MidTy->getScalarSizeInBits();
       if (MidSize >= PtrSize)
         return Instruction::BitCast;
       return 0;
@@ -2254,17 +2262,46 @@ unsigned CastInst::isEliminableCastPair(
       if (SrcTy == DstTy)
         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.
-      if (SrcTy->isPointerTy() && MidTy->isPointerTy())
+    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 -> intptr  if bitcast is a ptr to ptr cast
-      if (MidTy->isPointerTy() && DstTy->isPointerTy())
+    }
+    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)