[AliasAnalysis] Misc fixes for checking aliasing with scalable types.

[efriedma]

Summary

This is fixing up various places that use the implicit TypeSize->uint64_t conversion.

The new overloads in MemoryLocation.h are used in various places that construct a MemoryLocation from a TypeSize, including MemorySSA. (They were using the implicit conversion before.)

[sdesmalen]

llvm/lib/IR/Value.cpp

718

From the LangRef:

Scalable vectors cannot be global variables or members of structs or arrays because their size is unknown at compile time.

So I think this can use getFixedSize().

[efriedma]

Address review comment

[george.burgess.iv]

(I really need to circle back and finish the LocationSize migration...)

Not super familiar with the intricacies of scalable vectors, but these changes LGTM. Thanks!

[sdesmalen]

Same here, LGTM!

llvm/include/llvm/Analysis/MemoryLocation.h

public:
   // providing.
   //
   // Since the overwhelming majority of users of this provide precise values,
   // this assumes the provided value is precise.
   constexpr LocationSize(uint64_t Raw)
       : Value(Raw > MaxValue ? Unknown : Raw) {}
 
   static LocationSize precise(uint64_t Value) { return LocationSize(Value); }
+  static LocationSize precise(TypeSize Value) {
+    if (Value.isScalable())
+      return unknown();
+    return precise(Value.getFixedSize());
+  }
 
   static LocationSize upperBound(uint64_t Value) {
     // You can't go lower than 0, so give a precise result.
     if (LLVM_UNLIKELY(Value == 0))
       return precise(0);
     if (LLVM_UNLIKELY(Value > MaxValue))
       return unknown();
     return LocationSize(Value | ImpreciseBit, Direct);
   }
+  static LocationSize upperBound(TypeSize Value) {
+    if (Value.isScalable())
+      return unknown();
+    return upperBound(Value.getFixedSize());
+  }
 
   constexpr static LocationSize unknown() {
     return LocationSize(Unknown, Direct);
   }
 
   // Sentinel values, generally used for maps.
   constexpr static LocationSize mapTombstone() {
     return LocationSize(MapTombstone, Direct);

llvm/lib/Analysis/MemoryBuiltins.cpp

if (I.getBitWidth() != IntTyBits)
     I = I.zextOrTrunc(IntTyBits);
   return true;
 }
 
 SizeOffsetType ObjectSizeOffsetVisitor::visitAllocaInst(AllocaInst &I) {
   if (!I.getAllocatedType()->isSized())
     return unknown();
 
+  if (I.getAllocatedType()->isVectorTy() &&
+      I.getAllocatedType()->getVectorIsScalable())
+    return unknown();
+
   APInt Size(IntTyBits, DL.getTypeAllocSize(I.getAllocatedType()));
   if (!I.isArrayAllocation())
     return std::make_pair(align(Size, I.getAlignment()), Zero);
 
   Value *ArraySize = I.getArraySize();
   if (const ConstantInt *C = dyn_cast<ConstantInt>(ArraySize)) {
     APInt NumElems = C->getValue();
     if (!CheckedZextOrTrunc(NumElems))

llvm/lib/IR/Value.cpp

uint64_t Value::getPointerDereferenceableBytes(const DataLayout &DL,
 
   uint64_t DerefBytes = 0;
   CanBeNull = false;
   if (const Argument *A = dyn_cast<Argument>(this)) {
     DerefBytes = A->getDereferenceableBytes();
     if (DerefBytes == 0 && (A->hasByValAttr() || A->hasStructRetAttr())) {
       Type *PT = cast<PointerType>(A->getType())->getElementType();
       if (PT->isSized())
-        DerefBytes = DL.getTypeStoreSize(PT);
+        DerefBytes = DL.getTypeStoreSize(PT).getKnownMinSize();
     }
     if (DerefBytes == 0) {
       DerefBytes = A->getDereferenceableOrNullBytes();
       CanBeNull = true;
     }
   } else if (const auto *Call = dyn_cast<CallBase>(this)) {
     DerefBytes = Call->getDereferenceableBytes(AttributeList::ReturnIndex);
     if (DerefBytes == 0) {
if (DerefBytes == 0) {
               IP->getMetadata(LLVMContext::MD_dereferenceable_or_null)) {
         ConstantInt *CI = mdconst::extract<ConstantInt>(MD->getOperand(0));
         DerefBytes = CI->getLimitedValue();
       }
       CanBeNull = true;
     }
   } else if (auto *AI = dyn_cast<AllocaInst>(this)) {
     if (!AI->isArrayAllocation()) {
-      DerefBytes = DL.getTypeStoreSize(AI->getAllocatedType());
+      DerefBytes =
+          DL.getTypeStoreSize(AI->getAllocatedType()).getKnownMinSize();
       CanBeNull = false;
     }
   } else if (auto *GV = dyn_cast<GlobalVariable>(this)) {
     if (GV->getValueType()->isSized() && !GV->hasExternalWeakLinkage()) {
       // TODO: Don't outright reject hasExternalWeakLinkage but set the
       // CanBeNull flag.
-      DerefBytes = DL.getTypeStoreSize(GV->getValueType());
+      DerefBytes = DL.getTypeStoreSize(GV->getValueType()).getFixedSize();
       CanBeNull = false;
     }
   }
   return DerefBytes;
 }
 
 MaybeAlign Value::getPointerAlignment(const DataLayout &DL) const {
   assert(getType()->isPointerTy() && "must be pointer");

llvm/test/Analysis/MemorySSA/scalable-vec.ll

+; RUN: opt -basicaa -print-memoryssa -verify-memoryssa -analyze < %s 2>&1 | FileCheck %s
+; RUN: opt -aa-pipeline=basic-aa -passes='print<memoryssa>' -verify-memoryssa -disable-output < %s 2>&1 | FileCheck %s
+
+; CHECK-LABEL: define <vscale x 4 x i32> @f(
+; CHECK: 1 = MemoryDef(liveOnEntry)
+; CHECK: MemoryUse(1) MustAlias
+define <vscale x 4 x i32> @f(<vscale x 4 x i32> %z) {
+  %a = alloca <vscale x 4 x i32>
+  store <vscale x 4 x i32> %z, <vscale x 4 x i32>* %a
+  %zz = load <vscale x 4 x i32>, <vscale x 4 x i32>* %a
+  ret <vscale x 4 x i32> %zz
+}
+
+; CHECK-LABEL: define i32 @g(
+; CHECK: 1 = MemoryDef(liveOnEntry)
+; CHECK: MemoryUse(1) MayAlias
+declare i32* @gg(<vscale x 4 x i32>* %a)
+define i32 @g(i32 %z, i32 *%bb) {
+  %a = alloca <vscale x 4 x i32>
+  %aa = getelementptr <vscale x 4 x i32>, <vscale x 4 x i32>* %a, i32 0, i32 0
+  store i32 %z, i32* %aa
+  %bbb = call i32* @gg(<vscale x 4 x i32>* %a) readnone
+  %zz = load i32, i32* %bbb
+  ret i32 %zz
+}