[Alignment][NFC] Convert AllocaInst to MaybeAlign

[gchatelet]

Summary

This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790

[gchatelet]

• rebase

[courbet]

llvm/lib/Transforms/Scalar/SROA.cpp

4154–4155

why not getValueOrABITypeALignment() ?

[gchatelet]

• Address comments

[courbet]

llvm/lib/Transforms/Scalar/SROA.cpp

4157

merge + const ?

[gchatelet]

• Address comments

llvm/include/llvm/IR/Instructions.h

public:
   AllocaInst(Type *Ty, unsigned AddrSpace, Value *ArraySize,
              const Twine &Name, BasicBlock *InsertAtEnd);
 
   AllocaInst(Type *Ty, unsigned AddrSpace,
              const Twine &Name, Instruction *InsertBefore = nullptr);
   AllocaInst(Type *Ty, unsigned AddrSpace,
              const Twine &Name, BasicBlock *InsertAtEnd);
 
-  AllocaInst(Type *Ty, unsigned AddrSpace, Value *ArraySize, unsigned Align,
+  AllocaInst(Type *Ty, unsigned AddrSpace, Value *ArraySize, MaybeAlign Align,
              const Twine &Name = "", Instruction *InsertBefore = nullptr);
-  AllocaInst(Type *Ty, unsigned AddrSpace, Value *ArraySize, unsigned Align,
+  AllocaInst(Type *Ty, unsigned AddrSpace, Value *ArraySize, MaybeAlign Align,
              const Twine &Name, BasicBlock *InsertAtEnd);
 
   /// Return true if there is an allocation size parameter to the allocation
   /// instruction that is not 1.
   bool isArrayAllocation() const;
 
   /// Get the number of elements allocated. For a simple allocation of a single
   /// element, this will return a constant 1 value.

llvm/lib/AsmParser/LLParser.cpp

if (Lex.getKind() == lltok::kw_align) {
         }
       }
     }
   }
 
   if (Size && !Size->getType()->isIntegerTy())
     return Error(SizeLoc, "element count must have integer type");
 
-  AllocaInst *AI =
-      new AllocaInst(Ty, AddrSpace, Size, Alignment ? Alignment->value() : 0);
+  AllocaInst *AI = new AllocaInst(Ty, AddrSpace, Size, Alignment);
   AI->setUsedWithInAlloca(IsInAlloca);
   AI->setSwiftError(IsSwiftError);
   Inst = AI;
   return AteExtraComma ? InstExtraComma : InstNormal;
 }
 
 /// ParseLoad
 ///   ::= 'load' 'volatile'? TypeAndValue (',' 'align' i32)?

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

case bitc::FUNC_CODE_INST_ALLOCA: { // ALLOCA: [instty, opty, op, align]
       }
       if (!Ty || !Size)
         return error("Invalid record");
 
       // FIXME: Make this an optional field.
       const DataLayout &DL = TheModule->getDataLayout();
       unsigned AS = DL.getAllocaAddrSpace();
 
-      AllocaInst *AI = new AllocaInst(Ty, AS, Size, Align ? Align->value() : 0);
+      AllocaInst *AI = new AllocaInst(Ty, AS, Size, Align);
       AI->setUsedWithInAlloca(InAlloca);
       AI->setSwiftError(SwiftError);
       I = AI;
       FullTy = PointerType::get(FullTy, AS);
       InstructionList.push_back(I);
       break;
     }
     case bitc::FUNC_CODE_INST_LOAD: { // LOAD: [opty, op, align, vol]

llvm/lib/CodeGen/SjLjEHPrepare.cpp

 Value *SjLjEHPrepare::setupFunctionContext(Function &F,
                                            ArrayRef<LandingPadInst *> LPads) {
   BasicBlock *EntryBB = &F.front();
 
   // Create an alloca for the incoming jump buffer ptr and the new jump buffer
   // that needs to be restored on all exits from the function. This is an alloca
   // because the value needs to be added to the global context list.
   auto &DL = F.getParent()->getDataLayout();
-  unsigned Align = DL.getPrefTypeAlignment(FunctionContextTy);
-  FuncCtx = new AllocaInst(FunctionContextTy, DL.getAllocaAddrSpace(),
-                           nullptr, Align, "fn_context", &EntryBB->front());
+  const Align Alignment(DL.getPrefTypeAlignment(FunctionContextTy));
+  FuncCtx = new AllocaInst(FunctionContextTy, DL.getAllocaAddrSpace(), nullptr,
+                           Alignment, "fn_context", &EntryBB->front());
 
   // Fill in the function context structure.
   for (LandingPadInst *LPI : LPads) {
     IRBuilder<> Builder(LPI->getParent(),
                         LPI->getParent()->getFirstInsertionPt());
 
     // Reference the __data field.
     Value *FCData =

llvm/lib/IR/Instructions.cpp

AllocaInst::AllocaInst(Type *Ty, unsigned AddrSpace, const Twine &Name,
   : AllocaInst(Ty, AddrSpace, /*ArraySize=*/nullptr, Name, InsertBefore) {}
 
 AllocaInst::AllocaInst(Type *Ty, unsigned AddrSpace, const Twine &Name,
                        BasicBlock *InsertAtEnd)
   : AllocaInst(Ty, AddrSpace, /*ArraySize=*/nullptr, Name, InsertAtEnd) {}
 
 AllocaInst::AllocaInst(Type *Ty, unsigned AddrSpace, Value *ArraySize,
                        const Twine &Name, Instruction *InsertBefore)
-  : AllocaInst(Ty, AddrSpace, ArraySize, /*Align=*/0, Name, InsertBefore) {}
+    : AllocaInst(Ty, AddrSpace, ArraySize, /*Align=*/None, Name, InsertBefore) {
+}
 
 AllocaInst::AllocaInst(Type *Ty, unsigned AddrSpace, Value *ArraySize,
                        const Twine &Name, BasicBlock *InsertAtEnd)
-  : AllocaInst(Ty, AddrSpace, ArraySize, /*Align=*/0, Name, InsertAtEnd) {}
+    : AllocaInst(Ty, AddrSpace, ArraySize, /*Align=*/None, Name, InsertAtEnd) {}
 
 AllocaInst::AllocaInst(Type *Ty, unsigned AddrSpace, Value *ArraySize,
-                       unsigned Align, const Twine &Name,
+                       MaybeAlign Align, const Twine &Name,
                        Instruction *InsertBefore)
     : UnaryInstruction(PointerType::get(Ty, AddrSpace), Alloca,
                        getAISize(Ty->getContext(), ArraySize), InsertBefore),
       AllocatedType(Ty) {
   setAlignment(MaybeAlign(Align));
   assert(!Ty->isVoidTy() && "Cannot allocate void!");
   setName(Name);
 }
 
 AllocaInst::AllocaInst(Type *Ty, unsigned AddrSpace, Value *ArraySize,
-                       unsigned Align, const Twine &Name,
+                       MaybeAlign Align, const Twine &Name,
                        BasicBlock *InsertAtEnd)
     : UnaryInstruction(PointerType::get(Ty, AddrSpace), Alloca,
                        getAISize(Ty->getContext(), ArraySize), InsertAtEnd),
       AllocatedType(Ty) {
-  setAlignment(MaybeAlign(Align));
+  setAlignment(Align);
   assert(!Ty->isVoidTy() && "Cannot allocate void!");
   setName(Name);
 }
 
 void AllocaInst::setAlignment(MaybeAlign Align) {
   assert((!Align || *Align <= MaximumAlignment) &&
          "Alignment is greater than MaximumAlignment!");
   setInstructionSubclassData((getSubclassDataFromInstruction() & ~31) |
ExtractValueInst *ExtractValueInst::cloneImpl() const {
   return new ExtractValueInst(*this);
 }
 
 InsertValueInst *InsertValueInst::cloneImpl() const {
   return new InsertValueInst(*this);
 }
 
 AllocaInst *AllocaInst::cloneImpl() const {
-  AllocaInst *Result = new AllocaInst(getAllocatedType(),
-                                      getType()->getAddressSpace(),
-                                      (Value *)getOperand(0), getAlignment());
+  AllocaInst *Result =
+      new AllocaInst(getAllocatedType(), getType()->getAddressSpace(),
+                     (Value *)getOperand(0), MaybeAlign(getAlignment()));
   Result->setUsedWithInAlloca(isUsedWithInAlloca());
   Result->setSwiftError(isSwiftError());
   return Result;
 }
 
 LoadInst *LoadInst::cloneImpl() const {
   return new LoadInst(getType(), getOperand(0), Twine(), isVolatile(),
                       getAlignment(), getOrdering(), getSyncScopeID());

llvm/lib/Transforms/IPO/ArgumentPromotion.cpp

for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(),
 
     if (ByValArgsToTransform.count(&*I)) {
       // In the callee, we create an alloca, and store each of the new incoming
       // arguments into the alloca.
       Instruction *InsertPt = &NF->begin()->front();
 
       // Just add all the struct element types.
       Type *AgTy = cast<PointerType>(I->getType())->getElementType();
-      Value *TheAlloca = new AllocaInst(AgTy, DL.getAllocaAddrSpace(), nullptr,
-                                        I->getParamAlignment(), "", InsertPt);
+      Value *TheAlloca =
+          new AllocaInst(AgTy, DL.getAllocaAddrSpace(), nullptr,
+                         MaybeAlign(I->getParamAlignment()), "", InsertPt);
       StructType *STy = cast<StructType>(AgTy);
       Value *Idxs[2] = {ConstantInt::get(Type::getInt32Ty(F->getContext()), 0),
                         nullptr};
 
       for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
         Idxs[1] = ConstantInt::get(Type::getInt32Ty(F->getContext()), i);
         Value *Idx = GetElementPtrInst::Create(
             AgTy, TheAlloca, Idxs, TheAlloca->getName() + "." + Twine(i),

llvm/lib/Transforms/Scalar/SROA.cpp

AllocaInst *SROA::rewritePartition(AllocaInst &AI, AllocaSlices &AS,
   // P.beginOffset() can be non-zero even with the same type in a case with
   // out-of-bounds access (e.g. @PR35657 function in SROA/basictest.ll).
   AllocaInst *NewAI;
   if (SliceTy == AI.getAllocatedType() && P.beginOffset() == 0) {
     NewAI = &AI;
     // FIXME: We should be able to bail at this point with "nothing changed".
     // FIXME: We might want to defer PHI speculation until after here.
     // FIXME: return nullptr;
   } else {
-    unsigned Alignment = AI.getAlignment();
-    if (!Alignment) {
-      // The minimum alignment which users can rely on when the explicit
-      // alignment is omitted or zero is that required by the ABI for this
-      // type.
-      Alignment = DL.getABITypeAlignment(AI.getAllocatedType());
-    }
-    Alignment = MinAlign(Alignment, P.beginOffset());
+    // The minimum alignment which users can rely on when the explicit alignment
+    // is omitted or zero is that required by the ABI for this type.
+    Align Alignment = DL.getValueOrABITypeAlignment(
+        MaybeAlign(AI.getAlignment()), AI.getAllocatedType());
+    Alignment = commonAlignment(Alignment, P.beginOffset());
     // If we will get at least this much alignment from the type alone, leave
     // the alloca's alignment unconstrained.
-    if (Alignment <= DL.getABITypeAlignment(SliceTy))
-      Alignment = 0;
+    const bool IsUnconstrained = Alignment <= DL.getABITypeAlignment(SliceTy);
     NewAI = new AllocaInst(
-      SliceTy, AI.getType()->getAddressSpace(), nullptr, Alignment,
+        SliceTy, AI.getType()->getAddressSpace(), nullptr,
+        IsUnconstrained ? MaybeAlign() : Alignment,
         AI.getName() + ".sroa." + Twine(P.begin() - AS.begin()), &AI);
     // Copy the old AI debug location over to the new one.
     NewAI->setDebugLoc(AI.getDebugLoc());
     ++NumNewAllocas;
   }
 
   LLVM_DEBUG(dbgs() << "Rewriting alloca partition "
                     << "[" << P.beginOffset() << "," << P.endOffset()

llvm/lib/Transforms/Utils/InlineFunction.cpp

if (getOrEnforceKnownAlignment(Arg, 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.
-  unsigned Align = DL.getPrefTypeAlignment(AggTy);
+  Align Alignment(DL.getPrefTypeAlignment(AggTy));
 
   // If the byval had an alignment specified, we *must* use at least that
   // alignment, as it is required by the byval argument (and uses of the
   // pointer inside the callee).
-  Align = std::max(Align, ByValAlignment);
+  Alignment = max(Alignment, MaybeAlign(ByValAlignment));
 
-  Value *NewAlloca = new AllocaInst(AggTy, DL.getAllocaAddrSpace(),
-                                    nullptr, Align, Arg->getName(),
-                                    &*Caller->begin()->begin());
+  Value *NewAlloca =
+      new AllocaInst(AggTy, DL.getAllocaAddrSpace(), nullptr, Alignment,
+                     Arg->getName(), &*Caller->begin()->begin());
   IFI.StaticAllocas.push_back(cast<AllocaInst>(NewAlloca));
 
   // Uses of the argument in the function should use our new alloca
   // instead.
   return NewAlloca;
 }
 
 // Check whether this Value is used by a lifetime intrinsic.