[SandboxIR] Implement ConstantExpr (#109491)

This patch implements an empty sandboxir::ConstantExpr class, mirroring
llvm::ConstantExpr.

Author: vporpo

llvm/include/llvm/SandboxIR/SandboxIR.h

@@ -135,6 +135,7 @@ class GlobalVariable;
 class GlobalAlias;
 class NoCFIValue;
 class ConstantPtrAuth;
+class ConstantExpr;
 class Context;
 class Function;
 class Instruction;
@@ -344,6 +345,7 @@ class Value {
   friend class GlobalAlias;           // For `Val`.
   friend class NoCFIValue;            // For `Val`.
   friend class ConstantPtrAuth;       // For `Val`.
+  friend class ConstantExpr;          // For `Val`.
 
   /// All values point to the context.
   Context &Ctx;
@@ -1661,6 +1663,19 @@ class ConstantPtrAuth final : public Constant {
   }
 };
 
+class ConstantExpr : public Constant {
+  ConstantExpr(llvm::ConstantExpr *C, Context &Ctx)
+      : Constant(ClassID::ConstantExpr, C, Ctx) {}
+  friend class Context; // For constructor.
+
+public:
+  /// For isa/dyn_cast.
+  static bool classof(const sandboxir::Value *From) {
+    return From->getSubclassID() == ClassID::ConstantExpr;
+  }
+  // TODO: Missing functions.
+};
+
 class BlockAddress final : public Constant {
   BlockAddress(llvm::BlockAddress *C, Context &Ctx)
       : Constant(ClassID::BlockAddress, C, Ctx) {}

llvm/include/llvm/SandboxIR/SandboxIRValues.def

@@ -40,6 +40,7 @@ DEF_CONST(GlobalAlias, GlobalAlias)
 DEF_CONST(BlockAddress, BlockAddress)
 DEF_CONST(NoCFIValue, NoCFIValue)
 DEF_CONST(ConstantPtrAuth, ConstantPtrAuth)
+DEF_CONST(ConstantExpr, ConstantExpr)
 DEF_CONST(DSOLocalEquivalent, DSOLocalEquivalent)
 DEF_CONST(ConstantTokenNone, ConstantTokenNone)
 

llvm/lib/SandboxIR/SandboxIR.cpp

@@ -2888,6 +2888,10 @@ Value *Context::getOrCreateValueInternal(llvm::Value *LLVMV, llvm::User *U) {
       It->second = std::unique_ptr<ConstantPtrAuth>(
           new ConstantPtrAuth(cast<llvm::ConstantPtrAuth>(C), *this));
       break;
+    case llvm::Value::ConstantExprVal:
+      It->second = std::unique_ptr<ConstantExpr>(
+          new ConstantExpr(cast<llvm::ConstantExpr>(C), *this));
+      break;
     default:
       It->second = std::unique_ptr<Constant>(new Constant(C, *this));
       break;

llvm/unittests/SandboxIR/SandboxIRTest.cpp

@@ -1180,6 +1180,24 @@ define ptr @foo() {
   EXPECT_EQ(PtrAuth->getWithSameSchema(&F), PtrAuth);
 }
 
+TEST_F(SandboxIRTest, ConstantExpr) {
+  parseIR(C, R"IR(
+define i32 @foo() {
+  ret i32 ptrtoint (ptr @foo to i32)
+}
+)IR");
+  Function &LLVMF = *M->getFunction("foo");
+  sandboxir::Context Ctx(C);
+
+  auto &F = *Ctx.createFunction(&LLVMF);
+  auto *BB = &*F.begin();
+  auto It = BB->begin();
+  auto *Ret = cast<sandboxir::ReturnInst>(&*It++);
+  // Check classof(), creation.
+  [[maybe_unused]] auto *ConstExpr =
+      cast<sandboxir::ConstantExpr>(Ret->getReturnValue());
+}
+
 TEST_F(SandboxIRTest, BlockAddress) {
   parseIR(C, R"IR(
 define void @foo(ptr %ptr) {