[MemoryBuiltins] Support allocas in getInitialValueOfAllocation (NFC)

Author: nikic

llvm/lib/Analysis/MemoryBuiltins.cpp

@@ -428,6 +428,9 @@ llvm::getAllocSize(const CallBase *CB, const TargetLibraryInfo *TLI,
 Constant *llvm::getInitialValueOfAllocation(const Value *V,
                                             const TargetLibraryInfo *TLI,
                                             Type *Ty) {
+  if (isa<AllocaInst>(V))
+    return UndefValue::get(Ty);
+
   auto *Alloc = dyn_cast<CallBase>(V);
   if (!Alloc)
     return nullptr;

llvm/lib/Transforms/IPO/Attributor.cpp

@@ -242,8 +242,6 @@ Constant *
 AA::getInitialValueForObj(Attributor &A, const AbstractAttribute &QueryingAA,
                           Value &Obj, Type &Ty, const TargetLibraryInfo *TLI,
                           const DataLayout &DL, AA::RangeTy *RangePtr) {
-  if (isa<AllocaInst>(Obj))
-    return UndefValue::get(&Ty);
   if (Constant *Init = getInitialValueOfAllocation(&Obj, TLI, &Ty))
     return Init;
   auto *GV = dyn_cast<GlobalVariable>(&Obj);