[OpaquePtr] Support opaque constant expression GEP

Adjust assertions to use isOpaqueOrPointeeTypeMatches() and make
it return an opaque pointer result for an opaque base pointer. We
also need to enumerate the element type, as it is no longer
implicitly enumerated through the pointer type.

Differential Revision: https://reviews.llvm.org/D104655

1 files changed, 7 insertions, 5 deletions

diff --git a/llvm/lib/IR/Constants.cpp b/llvm/lib/IR/Constants.cpp
index 147e96c..2823a1e 100644
--- a/llvm/lib/IR/Constants.cpp
+++ b/llvm/lib/IR/Constants.cpp
@@ -2425,11 +2425,11 @@ Constant *ConstantExpr::getGetElementPtr(Type *Ty, Constant *C,
                                          ArrayRef<Value *> Idxs, bool InBounds,
                                          Optional<unsigned> InRangeIndex,
                                          Type *OnlyIfReducedTy) {
+  PointerType *OrigPtrTy = cast<PointerType>(C->getType()->getScalarType());
   if (!Ty)
-    Ty = cast<PointerType>(C->getType()->getScalarType())->getElementType();
+    Ty = OrigPtrTy->getElementType();
   else
-    assert(Ty ==
-           cast<PointerType>(C->getType()->getScalarType())->getElementType());
+    assert(OrigPtrTy->isOpaqueOrPointeeTypeMatches(Ty));
 
   if (Constant *FC =
           ConstantFoldGetElementPtr(Ty, C, InBounds, InRangeIndex, Idxs))
@@ -2438,8 +2438,10 @@ Constant *ConstantExpr::getGetElementPtr(Type *Ty, Constant *C,
   // Get the result type of the getelementptr!
   Type *DestTy = GetElementPtrInst::getIndexedType(Ty, Idxs);
   assert(DestTy && "GEP indices invalid!");
-  unsigned AS = C->getType()->getPointerAddressSpace();
-  Type *ReqTy = DestTy->getPointerTo(AS);
+  unsigned AS = OrigPtrTy->getAddressSpace();
+  Type *ReqTy = OrigPtrTy->isOpaque()
+      ? PointerType::get(OrigPtrTy->getContext(), AS)
+      : DestTy->getPointerTo(AS);
 
   auto EltCount = ElementCount::getFixed(0);
   if (VectorType *VecTy = dyn_cast<VectorType>(C->getType()))