[llvm] [SandboxIR] Implement PoisonValue (PR #107324)

[Sriraman Tallam via llvm-commits]

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@@ -1018,6 +1020,49 @@ class ConstantPointerNull final : public Constant {
 #endif
 };
 
+// TODO: Inherit from UndefValue.
+class PoisonValue final : public Constant {
+  PoisonValue(llvm::PoisonValue *C, Context &Ctx)
+      : Constant(ClassID::PoisonValue, C, Ctx) {}
+  friend class Context; // For constructor.
+
+public:
+  /// Static factory methods - Return an 'poison' object of the specified type.
+  static PoisonValue *get(Type *T);
+
+  /// If this poison has array or vector type, return a poison with the right
+  /// element type.
+  PoisonValue *getSequentialElement() const;
+
+  /// If this poison has struct type, return a poison with the right element
+  /// type for the specified element.
+  PoisonValue *getStructElement(unsigned Elt) const;
+
+  /// Return an poison of the right value for the specified GEP index if we can,
+  /// otherwise return null (e.g. if C is a ConstantExpr).
+  PoisonValue *getElementValue(Constant *C) const;
+
+  /// Return an poison of the right value for the specified GEP index.
+  PoisonValue *getElementValue(unsigned Idx) const;
+
+  /// For isa/dyn_cast.
+  static bool classof(const sandboxir::Value *From) {
+    return From->getSubclassID() == ClassID::PoisonValue;
+  }
+  unsigned getUseOperandNo(const Use &Use) const final {
+    llvm_unreachable("ConstantAggregateZero has no operands!");
----------------
tmsri wrote:

"PoisonValue has no operands!"

https://github.com/llvm/llvm-project/pull/107324