[InstCombine] Don't coerce non-integral pointers to integers

[majnemer]

LGTM

llvm/trunk/include/llvm/IR/DataLayout.h

public:
   }
 
   bool isNonIntegralPointerType(PointerType *PT) const {
     ArrayRef<unsigned> NonIntegralSpaces = getNonIntegralAddressSpaces();
     return find(NonIntegralSpaces, PT->getAddressSpace()) !=
            NonIntegralSpaces.end();
   }
 
+  bool isNonIntegralPointerType(Type *Ty) const {
+    auto *PTy = dyn_cast<PointerType>(Ty);
+    return PTy && isNonIntegralPointerType(PTy);
+  }
+
   /// Layout pointer size, in bits
   /// FIXME: The defaults need to be removed once all of
   /// the backends/clients are updated.
   unsigned getPointerSizeInBits(unsigned AS = 0) const {
     return getPointerSize(AS) * 8;
   }
 
   /// Layout pointer size, in bits, based on the type.  If this function is

llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp

static Instruction *combineLoadToOperationType(InstCombiner &IC, LoadInst &LI) {
   const DataLayout &DL = IC.getDataLayout();
 
   // Try to canonicalize loads which are only ever stored to operate over
   // integers instead of any other type. We only do this when the loaded type
   // is sized and has a size exactly the same as its store size and the store
   // size is a legal integer type.
   if (!Ty->isIntegerTy() && Ty->isSized() &&
       DL.isLegalInteger(DL.getTypeStoreSizeInBits(Ty)) &&
-      DL.getTypeStoreSizeInBits(Ty) == DL.getTypeSizeInBits(Ty)) {
+      DL.getTypeStoreSizeInBits(Ty) == DL.getTypeSizeInBits(Ty) &&
+      !DL.isNonIntegralPointerType(Ty)) {
     if (std::all_of(LI.user_begin(), LI.user_end(), [&LI](User *U) {
           auto *SI = dyn_cast<StoreInst>(U);
           return SI && SI->getPointerOperand() != &LI;
         })) {
       LoadInst *NewLoad = combineLoadToNewType(
           IC, LI,
           Type::getIntNTy(LI.getContext(), DL.getTypeStoreSizeInBits(Ty)));
       // Replace all the stores with stores of the newly loaded value.

llvm/trunk/test/Transforms/InstCombine/non-integral-pointers.ll

 define i8 addrspace(3)* @f_1() {
 ; inttoptr is fine here since addrspace(3) is integral.
 
 ; CHECK-LABEL: @f_1(
 ; CHECK: ret i8 addrspace(3)* inttoptr (i64 50 to i8 addrspace(3)*)
   %result = getelementptr i8, i8 addrspace(3)* null, i64 50
   ret i8 addrspace(3)* %result
 }
+
+define void @f_2(i8 addrspace(4)** %ptr0, i8 addrspace(4)** %ptr1) {
+; It is not okay to convert the load/store pair to load and store
+; integers, since pointers in address space 4 are non-integral.
+
+; CHECK-LABEL: @f_2(
+entry:
+; CHECK:  %val = load i8 addrspace(4)*, i8 addrspace(4)** %ptr0, align 8
+; CHECK:  store i8 addrspace(4)* %val, i8 addrspace(4)** %ptr1, align 8
+; CHECK-NOT: load i64
+; CHECK-NOT: store i64
+  %val = load i8 addrspace(4)*, i8 addrspace(4)** %ptr0
+  store i8 addrspace(4)* %val, i8 addrspace(4)** %ptr1
+  ret void
+}
+
+define void @f_3(i8 addrspace(3)** %ptr0, i8 addrspace(3)** %ptr1) {
+; It *is* okay to convert the load/store pair to load and store
+; integers, since pointers in address space 3 are integral.
+
+; CHECK-LABEL: @f_3(
+entry:
+; CHECK: load i64
+; CHECK:  store i64
+  %val = load i8 addrspace(3)*, i8 addrspace(3)** %ptr0
+  store i8 addrspace(3)* %val, i8 addrspace(3)** %ptr1
+  ret void
+}