[Local] Update getOrEnforceKnownAlignment/getKnownAlignment to use Align/MaybeAlign.

[craig.topper]

Properly account for the possiblity of MaybeAlign being unset in CodeGenPrepare.

[efriedma]

llvm/lib/Transforms/Vectorize/LoadStoreVectorizer.cpp

1019

Please use Align(), not MaybeAlign(), for values known to be non-zero.

[craig.topper]

Address review comment

[efriedma]

LGTM with one minor comment

llvm/lib/Transforms/Utils/InlineFunction.cpp

1377–1378

This can use Align(ByValAlignment)

[craig.topper]

I missed that there was a usage in clang

[craig.topper]

Fix for clang usage.

[efriedma]

clang/lib/CodeGen/CGCall.cpp

4181

Align.getAsAlign()

[craig.topper]

Use getAsAlign

[efriedma]

LGTM

[gchatelet]

Thx @craig.topper ! I'm happy to see this effort percolate :)

clang/lib/CodeGen/CGCall.cpp

case ABIArgInfo::Indirect: {
         assert((FirstIRArg >= IRFuncTy->getNumParams() ||
                 IRFuncTy->getParamType(FirstIRArg)->getPointerAddressSpace() ==
                     TD->getAllocaAddrSpace()) &&
                "indirect argument must be in alloca address space");
 
         bool NeedCopy = false;
 
         if (Addr.getAlignment() < Align &&
-            llvm::getOrEnforceKnownAlignment(V, Align.getQuantity(), *TD) <
-                Align.getQuantity()) {
+            llvm::getOrEnforceKnownAlignment(V, Align.getAsAlign(), *TD) <
+                Align.getAsAlign()) {
           NeedCopy = true;
         } else if (I->hasLValue()) {
           auto LV = I->getKnownLValue();
           auto AS = LV.getAddressSpace();
 
           if (!ArgInfo.getIndirectByVal() ||
               (LV.getAlignment() < getContext().getTypeAlignInChars(I->Ty))) {
             NeedCopy = true;

llvm/include/llvm/Transforms/Utils/Local.h

 /// the owning object can be modified and has an alignment less than \p
 /// PrefAlign, it will be increased and \p PrefAlign returned. If the alignment
 /// cannot be increased, the known alignment of the value is returned.
 ///
 /// It is not always possible to modify the alignment of the underlying object,
 /// so if alignment is important, a more reliable approach is to simply align
 /// all global variables and allocation instructions to their preferred
 /// alignment from the beginning.
-unsigned getOrEnforceKnownAlignment(Value *V, unsigned PrefAlign,
-                                    const DataLayout &DL,
-                                    const Instruction *CxtI = nullptr,
-                                    AssumptionCache *AC = nullptr,
-                                    const DominatorTree *DT = nullptr);
+Align getOrEnforceKnownAlignment(Value *V, MaybeAlign PrefAlign,
 
 /// Try to infer an alignment for the specified pointer.
-inline unsigned getKnownAlignment(Value *V, const DataLayout &DL,
-                                  const Instruction *CxtI = nullptr,
-                                  AssumptionCache *AC = nullptr,
-                                  const DominatorTree *DT = nullptr) {
-  return getOrEnforceKnownAlignment(V, 0, DL, CxtI, AC, DT);
+inline Align getKnownAlignment(Value *V, const DataLayout &DL,
+  return getOrEnforceKnownAlignment(V, MaybeAlign(), DL, CxtI, AC, DT);
 }
 
 /// Create a call that matches the invoke \p II in terms of arguments,
 /// attributes, debug information, etc. The call is not placed in a block and it
 /// will not have a name. The invoke instruction is not removed, nor are the
 /// uses replaced by the new call.
 CallInst *createCallMatchingInvoke(InvokeInst *II);
 

llvm/lib/CodeGen/CodeGenPrepare.cpp

for (auto &Arg : CI->arg_operands()) {
           GV->getPointerAlignment(*DL) < PrefAlign &&
           DL->getTypeAllocSize(GV->getValueType()) >=
               MinSize + Offset2)
         GV->setAlignment(MaybeAlign(PrefAlign));
     }
     // If this is a memcpy (or similar) then we may be able to improve the
     // alignment
     if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(CI)) {
-      unsigned DestAlign = getKnownAlignment(MI->getDest(), *DL);
-      if (DestAlign > MI->getDestAlignment())
+      Align DestAlign = getKnownAlignment(MI->getDest(), *DL);
+      MaybeAlign MIDestAlign = MI->getDestAlign();
+      if (!MIDestAlign || DestAlign > *MIDestAlign)
         MI->setDestAlignment(DestAlign);
       if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) {
-        unsigned SrcAlign = getKnownAlignment(MTI->getSource(), *DL);
-        if (SrcAlign > MTI->getSourceAlignment())
+        MaybeAlign MTISrcAlign = MTI->getSourceAlign();
+        Align SrcAlign = getKnownAlignment(MTI->getSource(), *DL);
+        if (!MTISrcAlign || SrcAlign > *MTISrcAlign)
           MTI->setSourceAlignment(SrcAlign);
       }
     }
   }
 
   // If we have a cold call site, try to sink addressing computation into the
   // cold block.  This interacts with our handling for loads and stores to
   // ensure that we can fold all uses of a potential addressing computation

llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp

bool Sign = V->getElementType()->isIntegerTy()
                     ? cast<ConstantInt>(Elt)->isNegative()
                     : cast<ConstantFP>(Elt)->isNegative();
     BoolVec.push_back(ConstantInt::get(BoolTy, Sign));
   }
   return ConstantVector::get(BoolVec);
 }
 
 Instruction *InstCombiner::SimplifyAnyMemTransfer(AnyMemTransferInst *MI) {
-  unsigned DstAlign = getKnownAlignment(MI->getRawDest(), DL, MI, &AC, &DT);
-  unsigned CopyDstAlign = MI->getDestAlignment();
-  if (CopyDstAlign < DstAlign){
+  Align DstAlign = getKnownAlignment(MI->getRawDest(), DL, MI, &AC, &DT);
+  MaybeAlign CopyDstAlign = MI->getDestAlign();
+  if (!CopyDstAlign || *CopyDstAlign < DstAlign) {
     MI->setDestAlignment(DstAlign);
     return MI;
   }
 
-  unsigned SrcAlign = getKnownAlignment(MI->getRawSource(), DL, MI, &AC, &DT);
-  unsigned CopySrcAlign = MI->getSourceAlignment();
-  if (CopySrcAlign < SrcAlign) {
+  Align SrcAlign = getKnownAlignment(MI->getRawSource(), DL, MI, &AC, &DT);
+  MaybeAlign CopySrcAlign = MI->getSourceAlign();
+  if (!CopySrcAlign || *CopySrcAlign < SrcAlign) {
     MI->setSourceAlignment(SrcAlign);
     return MI;
   }
 
   // If we have a store to a location which is known constant, we can conclude
   // that the store must be storing the constant value (else the memory
   // wouldn't be constant), and this must be a noop.
   if (AA->pointsToConstantMemory(MI->getDest())) {
Instruction *InstCombiner::SimplifyAnyMemTransfer(AnyMemTransferInst *MI) {
   }
 
   // Set the size of the copy to 0, it will be deleted on the next iteration.
   MI->setLength(Constant::getNullValue(MemOpLength->getType()));
   return MI;
 }
 
 Instruction *InstCombiner::SimplifyAnyMemSet(AnyMemSetInst *MI) {
-  const unsigned KnownAlignment =
+  const Align KnownAlignment =
       getKnownAlignment(MI->getDest(), DL, MI, &AC, &DT);
-  if (MI->getDestAlignment() < KnownAlignment) {
+  MaybeAlign MemSetAlign = MI->getDestAlign();
+  if (!MemSetAlign || *MemSetAlign < KnownAlignment) {
     MI->setDestAlignment(KnownAlignment);
     return MI;
   }
 
   // If we have a store to a location which is known constant, we can conclude
   // that the store must be storing the constant value (else the memory
   // wouldn't be constant), and this must be a noop.
   if (AA->pointsToConstantMemory(MI->getDest())) {
if (match(II->getArgOperand(0), m_OneUse(m_FNeg(m_Value(X))))) {
       FNeg->copyFastMathFlags(II);
       return FNeg;
     }
     break;
   }
   case Intrinsic::ppc_altivec_lvx:
   case Intrinsic::ppc_altivec_lvxl:
     // Turn PPC lvx -> load if the pointer is known aligned.
-    if (getOrEnforceKnownAlignment(II->getArgOperand(0), 16, DL, II, &AC,
+    if (getOrEnforceKnownAlignment(II->getArgOperand(0), Align(16), DL, II, &AC,
                                    &DT) >= 16) {
       Value *Ptr = Builder.CreateBitCast(II->getArgOperand(0),
                                          PointerType::getUnqual(II->getType()));
       return new LoadInst(II->getType(), Ptr);
     }
     break;
   case Intrinsic::ppc_vsx_lxvw4x:
   case Intrinsic::ppc_vsx_lxvd2x: {
     // Turn PPC VSX loads into normal loads.
     Value *Ptr = Builder.CreateBitCast(II->getArgOperand(0),
                                        PointerType::getUnqual(II->getType()));
     return new LoadInst(II->getType(), Ptr, Twine(""), false, Align(1));
   }
   case Intrinsic::ppc_altivec_stvx:
   case Intrinsic::ppc_altivec_stvxl:
     // Turn stvx -> store if the pointer is known aligned.
-    if (getOrEnforceKnownAlignment(II->getArgOperand(1), 16, DL, II, &AC,
+    if (getOrEnforceKnownAlignment(II->getArgOperand(1), Align(16), DL, II, &AC,
                                    &DT) >= 16) {
       Type *OpPtrTy =
         PointerType::getUnqual(II->getArgOperand(0)->getType());
       Value *Ptr = Builder.CreateBitCast(II->getArgOperand(1), OpPtrTy);
       return new StoreInst(II->getArgOperand(0), Ptr);
     }
     break;
   case Intrinsic::ppc_vsx_stxvw4x:
   case Intrinsic::ppc_vsx_stxvd2x: {
     // Turn PPC VSX stores into normal stores.
     Type *OpPtrTy = PointerType::getUnqual(II->getArgOperand(0)->getType());
     Value *Ptr = Builder.CreateBitCast(II->getArgOperand(1), OpPtrTy);
     return new StoreInst(II->getArgOperand(0), Ptr, false, Align(1));
   }
   case Intrinsic::ppc_qpx_qvlfs:
     // Turn PPC QPX qvlfs -> load if the pointer is known aligned.
-    if (getOrEnforceKnownAlignment(II->getArgOperand(0), 16, DL, II, &AC,
+    if (getOrEnforceKnownAlignment(II->getArgOperand(0), Align(16), DL, II, &AC,
                                    &DT) >= 16) {
       Type *VTy =
           VectorType::get(Builder.getFloatTy(),
                           cast<VectorType>(II->getType())->getElementCount());
       Value *Ptr = Builder.CreateBitCast(II->getArgOperand(0),
                                          PointerType::getUnqual(VTy));
       Value *Load = Builder.CreateLoad(VTy, Ptr);
       return new FPExtInst(Load, II->getType());
     }
     break;
   case Intrinsic::ppc_qpx_qvlfd:
     // Turn PPC QPX qvlfd -> load if the pointer is known aligned.
-    if (getOrEnforceKnownAlignment(II->getArgOperand(0), 32, DL, II, &AC,
+    if (getOrEnforceKnownAlignment(II->getArgOperand(0), Align(32), DL, II, &AC,
                                    &DT) >= 32) {
       Value *Ptr = Builder.CreateBitCast(II->getArgOperand(0),
                                          PointerType::getUnqual(II->getType()));
       return new LoadInst(II->getType(), Ptr);
     }
     break;
   case Intrinsic::ppc_qpx_qvstfs:
     // Turn PPC QPX qvstfs -> store if the pointer is known aligned.
-    if (getOrEnforceKnownAlignment(II->getArgOperand(1), 16, DL, II, &AC,
+    if (getOrEnforceKnownAlignment(II->getArgOperand(1), Align(16), DL, II, &AC,
                                    &DT) >= 16) {
       Type *VTy = VectorType::get(
           Builder.getFloatTy(),
           cast<VectorType>(II->getArgOperand(0)->getType())->getElementCount());
       Value *TOp = Builder.CreateFPTrunc(II->getArgOperand(0), VTy);
       Type *OpPtrTy = PointerType::getUnqual(VTy);
       Value *Ptr = Builder.CreateBitCast(II->getArgOperand(1), OpPtrTy);
       return new StoreInst(TOp, Ptr);
     }
     break;
   case Intrinsic::ppc_qpx_qvstfd:
     // Turn PPC QPX qvstfd -> store if the pointer is known aligned.
-    if (getOrEnforceKnownAlignment(II->getArgOperand(1), 32, DL, II, &AC,
+    if (getOrEnforceKnownAlignment(II->getArgOperand(1), Align(32), DL, II, &AC,
                                    &DT) >= 32) {
       Type *OpPtrTy =
         PointerType::getUnqual(II->getArgOperand(0)->getType());
       Value *Ptr = Builder.CreateBitCast(II->getArgOperand(1), OpPtrTy);
       return new StoreInst(II->getArgOperand(0), Ptr);
     }
     break;
 
if (Constant *Mask = dyn_cast<Constant>(II->getArgOperand(2))) {
                                                Builder.getInt32(i));
         }
         return CastInst::Create(Instruction::BitCast, Result, CI.getType());
       }
     }
     break;
 
   case Intrinsic::arm_neon_vld1: {
-    unsigned MemAlign = getKnownAlignment(II->getArgOperand(0),
-                                          DL, II, &AC, &DT);
-    if (Value *V = simplifyNeonVld1(*II, MemAlign, Builder))
+    Align MemAlign = getKnownAlignment(II->getArgOperand(0), DL, II, &AC, &DT);
+    if (Value *V = simplifyNeonVld1(*II, MemAlign.value(), Builder))
       return replaceInstUsesWith(*II, V);
     break;
   }
 
   case Intrinsic::arm_neon_vld2:
   case Intrinsic::arm_neon_vld3:
   case Intrinsic::arm_neon_vld4:
   case Intrinsic::arm_neon_vld2lane:
   case Intrinsic::arm_neon_vld3lane:
   case Intrinsic::arm_neon_vld4lane:
   case Intrinsic::arm_neon_vst1:
   case Intrinsic::arm_neon_vst2:
   case Intrinsic::arm_neon_vst3:
   case Intrinsic::arm_neon_vst4:
   case Intrinsic::arm_neon_vst2lane:
   case Intrinsic::arm_neon_vst3lane:
   case Intrinsic::arm_neon_vst4lane: {
-    unsigned MemAlign =
-        getKnownAlignment(II->getArgOperand(0), DL, II, &AC, &DT);
+    Align MemAlign = getKnownAlignment(II->getArgOperand(0), DL, II, &AC, &DT);
     unsigned AlignArg = II->getNumArgOperands() - 1;
     ConstantInt *IntrAlign = dyn_cast<ConstantInt>(II->getArgOperand(AlignArg));
-    if (IntrAlign && IntrAlign->getZExtValue() < MemAlign)
+    if (IntrAlign && IntrAlign->getZExtValue() < MemAlign.value())
       return replaceOperand(*II, AlignArg,
                             ConstantInt::get(Type::getInt32Ty(II->getContext()),
-                                             MemAlign, false));
+                                             MemAlign.value(), false));
     break;
   }
 
   case Intrinsic::arm_neon_vtbl1:
   case Intrinsic::aarch64_neon_tbl1:
     if (Value *V = simplifyNeonTbl1(*II, Builder))
       return replaceInstUsesWith(*II, V);
     break;

llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp

if (AI.getAlignment()) {
     // Check to see if this allocation is only modified by a memcpy/memmove from
     // a constant global whose alignment is equal to or exceeds that of the
     // allocation.  If this is the case, we can change all users to use
     // the constant global instead.  This is commonly produced by the CFE by
     // constructs like "void foo() { int A[] = {1,2,3,4,5,6,7,8,9...}; }" if 'A'
     // is only subsequently read.
     SmallVector<Instruction *, 4> ToDelete;
     if (MemTransferInst *Copy = isOnlyCopiedFromConstantGlobal(&AI, ToDelete)) {
-      unsigned SourceAlign = getOrEnforceKnownAlignment(
-          Copy->getSource(), AI.getAlignment(), DL, &AI, &AC, &DT);
-      if (AI.getAlignment() <= SourceAlign &&
+      MaybeAlign AllocaAlign = AI.getAlign();
+      Align SourceAlign = getOrEnforceKnownAlignment(
+          Copy->getSource(), AllocaAlign, DL, &AI, &AC, &DT);
+      if ((!AllocaAlign || *AllocaAlign <= SourceAlign) &&
           isDereferenceableForAllocaSize(Copy->getSource(), &AI, DL)) {
         LLVM_DEBUG(dbgs() << "Found alloca equal to global: " << AI << '\n');
         LLVM_DEBUG(dbgs() << "  memcpy = " << *Copy << '\n');
         for (unsigned i = 0, e = ToDelete.size(); i != e; ++i)
           eraseInstFromFunction(*ToDelete[i]);
         Constant *TheSrc = cast<Constant>(Copy->getSource());
         auto *SrcTy = TheSrc->getType();
         auto *DestTy = PointerType::get(AI.getType()->getPointerElementType(),

 Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
   Value *Op = LI.getOperand(0);
 
   // Try to canonicalize the loaded type.
   if (Instruction *Res = combineLoadToOperationType(*this, LI))
     return Res;
 
   // Attempt to improve the alignment.
-  unsigned KnownAlign = getOrEnforceKnownAlignment(
-      Op, DL.getPrefTypeAlignment(LI.getType()), DL, &LI, &AC, &DT);
-  unsigned LoadAlign = LI.getAlignment();
-  unsigned EffectiveLoadAlign =
-      LoadAlign != 0 ? LoadAlign : DL.getABITypeAlignment(LI.getType());
+  Align KnownAlign = getOrEnforceKnownAlignment(
+      Op, DL.getPrefTypeAlign(LI.getType()), DL, &LI, &AC, &DT);
+  MaybeAlign LoadAlign = LI.getAlign();
+  Align EffectiveLoadAlign =
+      LoadAlign ? *LoadAlign : DL.getABITypeAlign(LI.getType());
 
   if (KnownAlign > EffectiveLoadAlign)
-    LI.setAlignment(MaybeAlign(KnownAlign));
+    LI.setAlignment(KnownAlign);
   else if (LoadAlign == 0)
-    LI.setAlignment(MaybeAlign(EffectiveLoadAlign));
+    LI.setAlignment(EffectiveLoadAlign);
 
   // Replace GEP indices if possible.
   if (Instruction *NewGEPI = replaceGEPIdxWithZero(*this, Op, LI)) {
       Worklist.push(NewGEPI);
       return &LI;
   }
 
   if (Instruction *Res = unpackLoadToAggregate(*this, LI))
Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
   Value *Val = SI.getOperand(0);
   Value *Ptr = SI.getOperand(1);
 
   // Try to canonicalize the stored type.
   if (combineStoreToValueType(*this, SI))
     return eraseInstFromFunction(SI);
 
   // Attempt to improve the alignment.
-  const Align KnownAlign = Align(getOrEnforceKnownAlignment(
-      Ptr, DL.getPrefTypeAlignment(Val->getType()), DL, &SI, &AC, &DT));
-  const MaybeAlign StoreAlign = MaybeAlign(SI.getAlignment());
+  const Align KnownAlign = getOrEnforceKnownAlignment(
+      Ptr, DL.getPrefTypeAlign(Val->getType()), DL, &SI, &AC, &DT);
+  const MaybeAlign StoreAlign = SI.getAlign();
   const Align EffectiveStoreAlign =
-      StoreAlign ? *StoreAlign : Align(DL.getABITypeAlignment(Val->getType()));
+      StoreAlign ? *StoreAlign : DL.getABITypeAlign(Val->getType());
 
   if (KnownAlign > EffectiveStoreAlign)
     SI.setAlignment(KnownAlign);
   else if (!StoreAlign)
     SI.setAlignment(EffectiveStoreAlign);
 
   // Try to canonicalize the stored type.
   if (unpackStoreToAggregate(*this, SI))

llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp

bool MemCpyOptPass::processByValArgument(CallBase &CB, unsigned ArgNo) {
   MaybeAlign ByValAlign = CB.getParamAlign(ArgNo);
   if (!ByValAlign) return false;
 
   // If it is greater than the memcpy, then we check to see if we can force the
   // source of the memcpy to the alignment we need.  If we fail, we bail out.
   AssumptionCache &AC = LookupAssumptionCache();
   DominatorTree &DT = LookupDomTree();
   if (MDep->getSourceAlign() < ByValAlign &&
-      getOrEnforceKnownAlignment(MDep->getSource(), ByValAlign->value(), DL,
-                                 &CB, &AC, &DT) < ByValAlign->value())
+      getOrEnforceKnownAlignment(MDep->getSource(), ByValAlign, DL, &CB, &AC,
+                                 &DT) < ByValAlign)
     return false;
 
   // The address space of the memcpy source must match the byval argument
   if (MDep->getSource()->getType()->getPointerAddressSpace() !=
       ByValArg->getType()->getPointerAddressSpace())
     return false;
 
   // Verify that the copied-from memory doesn't change in between the memcpy and

llvm/lib/Transforms/Utils/InlineFunction.cpp

if (CalledFunc->onlyReadsMemory()) {
     if (ByValAlignment <= 1)  // 0 = unspecified, 1 = no particular alignment.
       return Arg;
 
     AssumptionCache *AC =
         IFI.GetAssumptionCache ? &(*IFI.GetAssumptionCache)(*Caller) : nullptr;
 
     // If the pointer is already known to be sufficiently aligned, or if we can
     // round it up to a larger alignment, then we don't need a temporary.
-    if (getOrEnforceKnownAlignment(Arg, ByValAlignment, DL, TheCall, AC) >=
-        ByValAlignment)
+    if (getOrEnforceKnownAlignment(Arg, Align(ByValAlignment), DL, TheCall,
+                                   AC) >= ByValAlignment)
       return Arg;
 
     // Otherwise, we have to make a memcpy to get a safe alignment.  This is bad
     // for code quality, but rarely happens and is required for correctness.
   }
 
   // Create the alloca.  If we have DataLayout, use nice alignment.
   Align Alignment(DL.getPrefTypeAlignment(AggTy));

llvm/lib/Transforms/Utils/Local.cpp

bool llvm::EliminateDuplicatePHINodes(BasicBlock *BB) {
   return Changed;
 }
 
 /// enforceKnownAlignment - If the specified pointer points to an object that
 /// we control, modify the object's alignment to PrefAlign. This isn't
 /// often possible though. If alignment is important, a more reliable approach
 /// is to simply align all global variables and allocation instructions to
 /// their preferred alignment from the beginning.
-static unsigned enforceKnownAlignment(Value *V, unsigned Alignment,
-                                      unsigned PrefAlign,
-                                      const DataLayout &DL) {
+static Align enforceKnownAlignment(Value *V, Align Alignment, Align PrefAlign,
   assert(PrefAlign > Alignment);
 
   V = V->stripPointerCasts();
 
   if (AllocaInst *AI = dyn_cast<AllocaInst>(V)) {
     // TODO: ideally, computeKnownBits ought to have used
     // AllocaInst::getAlignment() in its computation already, making
     // the below max redundant. But, as it turns out,
     // stripPointerCasts recurses through infinite layers of bitcasts,
     // while computeKnownBits is not allowed to traverse more than 6
     // levels.
-    Alignment = std::max(AI->getAlignment(), Alignment);
+    Alignment = max(AI->getAlign(), Alignment);
     if (PrefAlign <= Alignment)
       return Alignment;
 
     // If the preferred alignment is greater than the natural stack alignment
     // then don't round up. This avoids dynamic stack realignment.
-    if (DL.exceedsNaturalStackAlignment(Align(PrefAlign)))
+    if (DL.exceedsNaturalStackAlignment(PrefAlign))
       return Alignment;
-    AI->setAlignment(Align(PrefAlign));
+    AI->setAlignment(PrefAlign);
     return PrefAlign;
   }
 
   if (auto *GO = dyn_cast<GlobalObject>(V)) {
     // TODO: as above, this shouldn't be necessary.
-    Alignment = std::max(GO->getAlignment(), Alignment);
+    Alignment = max(GO->getAlign(), Alignment);
     if (PrefAlign <= Alignment)
       return Alignment;
 
     // If there is a large requested alignment and we can, bump up the alignment
     // of the global.  If the memory we set aside for the global may not be the
     // memory used by the final program then it is impossible for us to reliably
     // enforce the preferred alignment.
     if (!GO->canIncreaseAlignment())
       return Alignment;
 
-    GO->setAlignment(Align(PrefAlign));
+    GO->setAlignment(PrefAlign);
     return PrefAlign;
   }
 
   return Alignment;
 }
 
-unsigned llvm::getOrEnforceKnownAlignment(Value *V, unsigned PrefAlign,
-                                          const DataLayout &DL,
-                                          const Instruction *CxtI,
-                                          AssumptionCache *AC,
-                                          const DominatorTree *DT) {
+Align llvm::getOrEnforceKnownAlignment(Value *V, MaybeAlign PrefAlign,
   assert(V->getType()->isPointerTy() &&
          "getOrEnforceKnownAlignment expects a pointer!");
 
   KnownBits Known = computeKnownBits(V, DL, 0, AC, CxtI, DT);
   unsigned TrailZ = Known.countMinTrailingZeros();
 
   // Avoid trouble with ridiculously large TrailZ values, such as
   // those computed from a null pointer.
   // LLVM doesn't support alignments larger than (1 << MaxAlignmentExponent).
   TrailZ = std::min(TrailZ, +Value::MaxAlignmentExponent);
 
-  unsigned Align = 1u << std::min(Known.getBitWidth() - 1, TrailZ);
+  Align Alignment = Align(1u << std::min(Known.getBitWidth() - 1, TrailZ));
 
-  if (PrefAlign > Align)
-    Align = enforceKnownAlignment(V, Align, PrefAlign, DL);
+  if (PrefAlign && *PrefAlign > Alignment)
+    Alignment = enforceKnownAlignment(V, Alignment, *PrefAlign, DL);
 
   // We don't need to make any adjustment.
-  return Align;
+  return Alignment;
 }
 
 ///===---------------------------------------------------------------------===//
 ///  Dbg Intrinsic utilities
 ///
 
 /// See if there is a dbg.value intrinsic for DIVar for the PHI node.
 static bool PhiHasDebugValue(DILocalVariable *DIVar,

llvm/lib/Transforms/Vectorize/LoadStoreVectorizer.cpp

bool Vectorizer::vectorizeStoreChain(
   // If the store is going to be misaligned, don't vectorize it.
   if (accessIsMisaligned(SzInBytes, AS, Alignment.value())) {
     if (S0->getPointerAddressSpace() != DL.getAllocaAddrSpace()) {
       auto Chains = splitOddVectorElts(Chain, Sz);
       return vectorizeStoreChain(Chains.first, InstructionsProcessed) |
              vectorizeStoreChain(Chains.second, InstructionsProcessed);
     }
 
-    unsigned NewAlign = getOrEnforceKnownAlignment(S0->getPointerOperand(),
-                                                   StackAdjustedAlignment,
-                                                   DL, S0, nullptr, &DT);
-    if (NewAlign >= Alignment.value())
-      Alignment = Align(NewAlign);
+    Align NewAlign = getOrEnforceKnownAlignment(S0->getPointerOperand(),
+                                                Align(StackAdjustedAlignment),
+    if (NewAlign >= Alignment)
+      Alignment = NewAlign;
     else
       return false;
   }
 
   if (!TTI.isLegalToVectorizeStoreChain(SzInBytes, Alignment.value(), AS)) {
     auto Chains = splitOddVectorElts(Chain, Sz);
     return vectorizeStoreChain(Chains.first, InstructionsProcessed) |
            vectorizeStoreChain(Chains.second, InstructionsProcessed);
bool Vectorizer::vectorizeLoadChain(
   // If the load is going to be misaligned, don't vectorize it.
   if (accessIsMisaligned(SzInBytes, AS, Alignment.value())) {
     if (L0->getPointerAddressSpace() != DL.getAllocaAddrSpace()) {
       auto Chains = splitOddVectorElts(Chain, Sz);
       return vectorizeLoadChain(Chains.first, InstructionsProcessed) |
              vectorizeLoadChain(Chains.second, InstructionsProcessed);
     }
 
-    unsigned NewAlign = getOrEnforceKnownAlignment(
-      L0->getPointerOperand(), StackAdjustedAlignment, DL, L0, nullptr, &DT);
-    if (NewAlign >= Alignment.value())
-      Alignment = Align(NewAlign);
+    Align NewAlign = getOrEnforceKnownAlignment(L0->getPointerOperand(),
+                                                Align(StackAdjustedAlignment),
+                                                DL, L0, nullptr, &DT);
+    if (NewAlign >= Alignment)
+      Alignment = NewAlign;
     else
       return false;
   }
 
   if (!TTI.isLegalToVectorizeLoadChain(SzInBytes, Alignment.value(), AS)) {
     auto Chains = splitOddVectorElts(Chain, Sz);
     return vectorizeLoadChain(Chains.first, InstructionsProcessed) |
            vectorizeLoadChain(Chains.second, InstructionsProcessed);