[SandboxIR] Implement UndefValue (#107628)

This patch implements sandboxir::UndefValue mirroring llvm::UndefValue.

llvm/include/llvm/SandboxIR/SandboxIR.h

@@ -321,6 +321,7 @@ class Value {
   friend class ConstantStruct;        // For `Val`.
   friend class ConstantAggregateZero; // For `Val`.
   friend class ConstantPointerNull;   // For `Val`.
+  friend class UndefValue;            // For `Val`.
   friend class PoisonValue;           // For `Val`.
 
   /// All values point to the context.
@@ -1020,10 +1021,61 @@ class ConstantPointerNull final : public Constant {
 #endif
 };
 
-// TODO: Inherit from UndefValue.
-class PoisonValue final : public Constant {
+// TODO: Inherit from ConstantData.
+class UndefValue : public Constant {
+protected:
+  UndefValue(llvm::UndefValue *C, Context &Ctx)
+      : Constant(ClassID::UndefValue, C, Ctx) {}
+  UndefValue(ClassID ID, llvm::Constant *C, Context &Ctx)
+      : Constant(ID, C, Ctx) {}
+  friend class Context; // For constructor.
+
+public:
+  /// Static factory methods - Return an 'undef' object of the specified type.
+  static UndefValue *get(Type *T);
+
+  /// If this Undef has array or vector type, return a undef with the right
+  /// element type.
+  UndefValue *getSequentialElement() const;
+
+  /// If this undef has struct type, return a undef with the right element type
+  /// for the specified element.
+  UndefValue *getStructElement(unsigned Elt) const;
+
+  /// Return an undef of the right value for the specified GEP index if we can,
+  /// otherwise return null (e.g. if C is a ConstantExpr).
+  UndefValue *getElementValue(Constant *C) const;
+
+  /// Return an undef of the right value for the specified GEP index.
+  UndefValue *getElementValue(unsigned Idx) const;
+
+  /// Return the number of elements in the array, vector, or struct.
+  unsigned getNumElements() const {
+    return cast<llvm::UndefValue>(Val)->getNumElements();
+  }
+
+  /// For isa/dyn_cast.
+  static bool classof(const sandboxir::Value *From) {
+    return From->getSubclassID() == ClassID::UndefValue ||
+           From->getSubclassID() == ClassID::PoisonValue;
+  }
+  unsigned getUseOperandNo(const Use &Use) const final {
+    llvm_unreachable("UndefValue has no operands!");
+  }
+#ifndef NDEBUG
+  void verify() const override {
+    assert(isa<llvm::UndefValue>(Val) && "Expected an UndefValue!");
+  }
+  void dumpOS(raw_ostream &OS) const override {
+    dumpCommonPrefix(OS);
+    dumpCommonSuffix(OS);
+  }
+#endif
+};
+
+class PoisonValue final : public UndefValue {
   PoisonValue(llvm::PoisonValue *C, Context &Ctx)
-      : Constant(ClassID::PoisonValue, C, Ctx) {}
+      : UndefValue(ClassID::PoisonValue, C, Ctx) {}
   friend class Context; // For constructor.
 
 public:
@@ -1049,9 +1101,6 @@ class PoisonValue final : public Constant {
   static bool classof(const sandboxir::Value *From) {
     return From->getSubclassID() == ClassID::PoisonValue;
   }
-  unsigned getUseOperandNo(const Use &Use) const final {
-    llvm_unreachable("PoisonValue has no operands!");
-  }
 #ifndef NDEBUG
   void verify() const override {
     assert(isa<llvm::PoisonValue>(Val) && "Expected a PoisonValue!");

llvm/include/llvm/SandboxIR/SandboxIRValues.def

@@ -32,6 +32,7 @@ DEF_CONST(ConstantStruct, ConstantStruct)
 DEF_CONST(ConstantVector, ConstantVector)
 DEF_CONST(ConstantAggregateZero, ConstantAggregateZero)
 DEF_CONST(ConstantPointerNull, ConstantPointerNull)
+DEF_CONST(UndefValue, UndefValue)
 DEF_CONST(PoisonValue, PoisonValue)
 
 #ifndef DEF_INSTR

llvm/lib/SandboxIR/SandboxIR.cpp

@@ -2437,6 +2437,32 @@ PointerType *ConstantPointerNull::getType() const {
       Ctx.getType(cast<llvm::ConstantPointerNull>(Val)->getType()));
 }
 
+UndefValue *UndefValue::get(Type *T) {
+  auto *LLVMC = llvm::UndefValue::get(T->LLVMTy);
+  return cast<UndefValue>(T->getContext().getOrCreateConstant(LLVMC));
+}
+
+UndefValue *UndefValue::getSequentialElement() const {
+  return cast<UndefValue>(Ctx.getOrCreateConstant(
+      cast<llvm::UndefValue>(Val)->getSequentialElement()));
+}
+
+UndefValue *UndefValue::getStructElement(unsigned Elt) const {
+  return cast<UndefValue>(Ctx.getOrCreateConstant(
+      cast<llvm::UndefValue>(Val)->getStructElement(Elt)));
+}
+
+UndefValue *UndefValue::getElementValue(Constant *C) const {
+  return cast<UndefValue>(
+      Ctx.getOrCreateConstant(cast<llvm::UndefValue>(Val)->getElementValue(
+          cast<llvm::Constant>(C->Val))));
+}
+
+UndefValue *UndefValue::getElementValue(unsigned Idx) const {
+  return cast<UndefValue>(Ctx.getOrCreateConstant(
+      cast<llvm::UndefValue>(Val)->getElementValue(Idx)));
+}
+
 PoisonValue *PoisonValue::get(Type *T) {
   auto *LLVMC = llvm::PoisonValue::get(T->LLVMTy);
   return cast<PoisonValue>(T->getContext().getOrCreateConstant(LLVMC));
@@ -2580,6 +2606,10 @@ Value *Context::getOrCreateValueInternal(llvm::Value *LLVMV, llvm::User *U) {
       It->second = std::unique_ptr<PoisonValue>(
           new PoisonValue(cast<llvm::PoisonValue>(C), *this));
       return It->second.get();
+    case llvm::Value::UndefValueVal:
+      It->second = std::unique_ptr<UndefValue>(
+          new UndefValue(cast<llvm::UndefValue>(C), *this));
+      return It->second.get();
     case llvm::Value::ConstantArrayVal:
       It->second = std::unique_ptr<ConstantArray>(
           new ConstantArray(cast<llvm::ConstantArray>(C), *this));

llvm/unittests/SandboxIR/SandboxIRTest.cpp

@@ -642,6 +642,7 @@ define void @foo() {
   // Check classof() and creation.
   auto *Poison = cast<sandboxir::PoisonValue>(I0->getOperand(0));
   EXPECT_EQ(Poison->getType(), Int32Ty);
+  EXPECT_TRUE(isa<sandboxir::UndefValue>(Poison)); // Poison is Undef
   // Check get().
   auto *NewPoison = sandboxir::PoisonValue::get(Int32Ty);
   EXPECT_EQ(NewPoison, Poison);
@@ -670,6 +671,64 @@ define void @foo() {
             sandboxir::PoisonValue::get(Int8Ty));
 }
 
+TEST_F(SandboxIRTest, UndefValue) {
+  parseIR(C, R"IR(
+define void @foo() {
+  %i0 = add i32 undef, undef
+  %i1 = add <2 x i32> undef, undef
+  %i2 = extractvalue {i32, i8} undef, 0
+  ret void
+}
+)IR");
+  Function &LLVMF = *M->getFunction("foo");
+  sandboxir::Context Ctx(C);
+
+  auto &F = *Ctx.createFunction(&LLVMF);
+  auto &BB = *F.begin();
+  auto It = BB.begin();
+  auto *I0 = &*It++;
+  auto *I1 = &*It++;
+  auto *I2 = &*It++;
+  auto *Int32Ty = sandboxir::Type::getInt32Ty(Ctx);
+  auto *Int8Ty = sandboxir::Type::getInt8Ty(Ctx);
+  auto *Zero32 = sandboxir::ConstantInt::get(Int32Ty, 0u);
+  auto *One32 = sandboxir::ConstantInt::get(Int32Ty, 1u);
+
+  // Check classof() and creation.
+  auto *Undef = cast<sandboxir::UndefValue>(I0->getOperand(0));
+  EXPECT_EQ(Undef->getType(), Int32Ty);
+  EXPECT_FALSE(isa<sandboxir::PoisonValue>(Undef)); // Undef is not Poison
+  // Check get().
+  auto *NewUndef = sandboxir::UndefValue::get(Int32Ty);
+  EXPECT_EQ(NewUndef, Undef);
+  auto *NewUndef2 =
+      sandboxir::UndefValue::get(sandboxir::PointerType::get(Ctx, 0u));
+  EXPECT_NE(NewUndef2, Undef);
+  // Check getSequentialElement().
+  auto *UndefVector = cast<sandboxir::UndefValue>(I1->getOperand(0));
+  auto *SeqElm = UndefVector->getSequentialElement();
+  EXPECT_EQ(SeqElm->getType(), Int32Ty);
+  // Check getStructElement().
+  auto *UndefStruct = cast<sandboxir::UndefValue>(I2->getOperand(0));
+  auto *StrElm0 = UndefStruct->getStructElement(0);
+  auto *StrElm1 = UndefStruct->getStructElement(1);
+  EXPECT_EQ(StrElm0->getType(), Int32Ty);
+  EXPECT_EQ(StrElm1->getType(), Int8Ty);
+  // Check getElementValue(Constant)
+  EXPECT_EQ(UndefStruct->getElementValue(Zero32),
+            sandboxir::UndefValue::get(Int32Ty));
+  EXPECT_EQ(UndefStruct->getElementValue(One32),
+            sandboxir::UndefValue::get(Int8Ty));
+  // Check getElementValue(unsigned)
+  EXPECT_EQ(UndefStruct->getElementValue(0u),
+            sandboxir::UndefValue::get(Int32Ty));
+  EXPECT_EQ(UndefStruct->getElementValue(1u),
+            sandboxir::UndefValue::get(Int8Ty));
+  // Check getNumElements().
+  EXPECT_EQ(UndefVector->getNumElements(), 2u);
+  EXPECT_EQ(UndefStruct->getNumElements(), 2u);
+}
+
 TEST_F(SandboxIRTest, Use) {
   parseIR(C, R"IR(
 define i32 @foo(i32 %v0, i32 %v1) {