[opaque pointer type] Change GetElementPtrInst::getIndexedType to take the pointee type

This pushes the use of PointerType::getElementType up into several
callers - I'll essentially just have to keep pushing that up the stack
until I can eliminate every call to it...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233604 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp

@@ -611,8 +611,10 @@ static bool canReplaceGEPIdxWithZero(InstCombiner &IC, GetElementPtrInst *GEPI,
     return false;
 
   SmallVector<Value *, 4> Ops(GEPI->idx_begin(), GEPI->idx_begin() + Idx);
-  Type *AllocTy =
-    GetElementPtrInst::getIndexedType(GEPI->getOperand(0)->getType(), Ops);
+  Type *AllocTy = GetElementPtrInst::getIndexedType(
+      cast<PointerType>(GEPI->getOperand(0)->getType()->getScalarType())
+          ->getElementType(),
+      Ops);
   if (!AllocTy || !AllocTy->isSized())
     return false;
   const DataLayout &DL = IC.getDataLayout();