[libc] [clang] [lldb] [llvm] [mlir] [NFC][ObjectSizeOffset] Use classes instead of std::pair (PR #76882)

[Bill Wendling via cfe-commits]

================
@@ -187,80 +187,147 @@ Value *lowerObjectSizeCall(
     const TargetLibraryInfo *TLI, AAResults *AA, bool MustSucceed,
     SmallVectorImpl<Instruction *> *InsertedInstructions = nullptr);
 
-using SizeOffsetType = std::pair<APInt, APInt>;
+/// SizeOffsetType - A base template class for the object size visitors. Used
+/// here as a self-documenting way to handle the values rather than using a
+/// \p std::pair.
+template <typename T> struct SizeOffsetType {
+  T Size;
+  T Offset;
+
+  bool knownSize() const;
+  bool knownOffset() const;
+  bool anyKnown() const;
+  bool bothKnown() const;
+};
+
+/// SizeOffsetType<APInt> - Used by \p ObjectSizeOffsetVisitor, which works
+/// with \p APInts.
+template <> struct SizeOffsetType<APInt> {
+  APInt Size;
+  APInt Offset;
+
+  SizeOffsetType() = default;
+  SizeOffsetType(APInt Size, APInt Offset) : Size(Size), Offset(Offset) {}
+
+  bool knownSize() const { return Size.getBitWidth() > 1; }
+  bool knownOffset() const { return Offset.getBitWidth() > 1; }
+  bool anyKnown() const { return knownSize() || knownOffset(); }
+  bool bothKnown() const { return knownSize() && knownOffset(); }
+
+  bool operator==(const SizeOffsetType<APInt> &RHS) {
+    return Size == RHS.Size && Offset == RHS.Offset;
+  }
+  bool operator!=(const SizeOffsetType<APInt> &RHS) { return !(*this == RHS); }
+};
+using SizeOffsetAPInt = SizeOffsetType<APInt>;
 
 /// Evaluate the size and offset of an object pointed to by a Value*
 /// statically. Fails if size or offset are not known at compile time.
 class ObjectSizeOffsetVisitor
-  : public InstVisitor<ObjectSizeOffsetVisitor, SizeOffsetType> {
+    : public InstVisitor<ObjectSizeOffsetVisitor, SizeOffsetAPInt> {
   const DataLayout &DL;
   const TargetLibraryInfo *TLI;
   ObjectSizeOpts Options;
   unsigned IntTyBits;
   APInt Zero;
-  SmallDenseMap<Instruction *, SizeOffsetType, 8> SeenInsts;
+  SmallDenseMap<Instruction *, SizeOffsetAPInt, 8> SeenInsts;
   unsigned InstructionsVisited;
 
   APInt align(APInt Size, MaybeAlign Align);
 
-  SizeOffsetType unknown() {
-    return std::make_pair(APInt(), APInt());
-  }
+  static SizeOffsetAPInt unknown;
 
 public:
   ObjectSizeOffsetVisitor(const DataLayout &DL, const TargetLibraryInfo *TLI,
                           LLVMContext &Context, ObjectSizeOpts Options = {});
 
-  SizeOffsetType compute(Value *V);
-
-  static bool knownSize(const SizeOffsetType &SizeOffset) {
-    return SizeOffset.first.getBitWidth() > 1;
-  }
-
-  static bool knownOffset(const SizeOffsetType &SizeOffset) {
-    return SizeOffset.second.getBitWidth() > 1;
-  }
-
-  static bool bothKnown(const SizeOffsetType &SizeOffset) {
-    return knownSize(SizeOffset) && knownOffset(SizeOffset);
-  }
+  SizeOffsetAPInt compute(Value *V);
 
   // These are "private", except they can't actually be made private. Only
   // compute() should be used by external users.
-  SizeOffsetType visitAllocaInst(AllocaInst &I);
-  SizeOffsetType visitArgument(Argument &A);
-  SizeOffsetType visitCallBase(CallBase &CB);
-  SizeOffsetType visitConstantPointerNull(ConstantPointerNull&);
-  SizeOffsetType visitExtractElementInst(ExtractElementInst &I);
-  SizeOffsetType visitExtractValueInst(ExtractValueInst &I);
-  SizeOffsetType visitGlobalAlias(GlobalAlias &GA);
-  SizeOffsetType visitGlobalVariable(GlobalVariable &GV);
-  SizeOffsetType visitIntToPtrInst(IntToPtrInst&);
-  SizeOffsetType visitLoadInst(LoadInst &I);
-  SizeOffsetType visitPHINode(PHINode&);
-  SizeOffsetType visitSelectInst(SelectInst &I);
-  SizeOffsetType visitUndefValue(UndefValue&);
-  SizeOffsetType visitInstruction(Instruction &I);
+  SizeOffsetAPInt visitAllocaInst(AllocaInst &I);
+  SizeOffsetAPInt visitArgument(Argument &A);
+  SizeOffsetAPInt visitCallBase(CallBase &CB);
+  SizeOffsetAPInt visitConstantPointerNull(ConstantPointerNull &);
+  SizeOffsetAPInt visitExtractElementInst(ExtractElementInst &I);
+  SizeOffsetAPInt visitExtractValueInst(ExtractValueInst &I);
+  SizeOffsetAPInt visitGlobalAlias(GlobalAlias &GA);
+  SizeOffsetAPInt visitGlobalVariable(GlobalVariable &GV);
+  SizeOffsetAPInt visitIntToPtrInst(IntToPtrInst &);
+  SizeOffsetAPInt visitLoadInst(LoadInst &I);
+  SizeOffsetAPInt visitPHINode(PHINode &);
+  SizeOffsetAPInt visitSelectInst(SelectInst &I);
+  SizeOffsetAPInt visitUndefValue(UndefValue &);
+  SizeOffsetAPInt visitInstruction(Instruction &I);
 
 private:
-  SizeOffsetType findLoadSizeOffset(
+  SizeOffsetAPInt findLoadSizeOffset(
       LoadInst &LoadFrom, BasicBlock &BB, BasicBlock::iterator From,
-      SmallDenseMap<BasicBlock *, SizeOffsetType, 8> &VisitedBlocks,
+      SmallDenseMap<BasicBlock *, SizeOffsetAPInt, 8> &VisitedBlocks,
       unsigned &ScannedInstCount);
-  SizeOffsetType combineSizeOffset(SizeOffsetType LHS, SizeOffsetType RHS);
-  SizeOffsetType computeImpl(Value *V);
-  SizeOffsetType computeValue(Value *V);
+  SizeOffsetAPInt combineSizeOffset(SizeOffsetAPInt LHS, SizeOffsetAPInt RHS);
+  SizeOffsetAPInt computeImpl(Value *V);
+  SizeOffsetAPInt computeValue(Value *V);
   bool CheckedZextOrTrunc(APInt &I);
 };
 
-using SizeOffsetEvalType = std::pair<Value *, Value *>;
+template <> struct SizeOffsetType<WeakTrackingVH>;
+
+/// SizeOffsetType<Value *> - Used by \p ObjectSizeOffsetEvaluator, which works
+/// with \p Values.
+template <> struct SizeOffsetType<Value *> {
+  Value *Size;
+  Value *Offset;
+
+  SizeOffsetType() = default;
+  SizeOffsetType(Value *Size, Value *Offset) : Size(Size), Offset(Offset) {}
+  SizeOffsetType(SizeOffsetType<WeakTrackingVH> &SOT);
----------------
bwendling wrote:

The `SizeOffsetType<WeakTrackingVH>` is defined just below this struct. I had to do it this way because they both reference the other. (Well, I suppose I could have put the `WeakTrackingVH` first, but the `Value *` one was already here. :-)

https://github.com/llvm/llvm-project/pull/76882