[CIR] Upstream enum support (#136807)

Author: Ankur-0429

clang/include/clang/CIR/MissingFeatures.h

@@ -179,6 +179,7 @@ struct MissingFeatures {
   static bool msabi() { return false; }
   static bool typeChecks() { return false; }
   static bool lambdaFieldToName() { return false; }
+  static bool updateCompletedType() { return false; }
   static bool targetSpecificCXXABI() { return false; }
   static bool moduleNameHash() { return false; }
   static bool setDSOLocal() { return false; }

clang/lib/CIR/CodeGen/CIRGenModule.cpp

@@ -787,7 +787,7 @@ void CIRGenModule::emitTopLevelDecl(Decl *decl) {
   case Decl::OpenACCDeclare:
     emitGlobalOpenACCDecl(cast<OpenACCDeclareDecl>(decl));
     break;
-
+  case Decl::Enum:
   case Decl::UsingDirective: // using namespace X; [C++]
   case Decl::Typedef:
   case Decl::TypeAlias: // using foo = bar; [C++11]

clang/lib/CIR/CodeGen/CIRGenTypes.cpp

@@ -420,6 +420,19 @@ mlir::Type CIRGenTypes::convertType(QualType type) {
     break;
   }
 
+  case Type::Enum: {
+    // TODO(cir): Implement updateCompletedType for enums.
+    assert(!cir::MissingFeatures::updateCompletedType());
+    const EnumDecl *ED = cast<EnumType>(ty)->getDecl();
+    if (auto integerType = ED->getIntegerType(); !integerType.isNull())
+      return convertType(integerType);
+    // Return a placeholder 'i32' type.  This can be changed later when the
+    // type is defined (see UpdateCompletedType), but is likely to be the
+    // "right" answer.
+    resultType = cgm.UInt32Ty;
+    break;
+  }
+
   case Type::FunctionNoProto:
   case Type::FunctionProto:
     resultType = convertFunctionTypeInternal(type);

clang/test/CIR/CodeGen/basic.c

@@ -253,3 +253,29 @@ size_type max_size(void) {
 
 // OGCG: define{{.*}} i64 @max_size()
 // OGCG:   ret i64 2305843009213693951
+// CHECK:   cir.store %5, %0 : !u64i, !cir.ptr<!u64i>
+// CHECK:   %6 = cir.load %0 : !cir.ptr<!u64i>, !u64i
+// CHECK:   cir.return %6 : !u64i
+// CHECK:   }
+
+enum A {
+  A_one,
+  A_two
+};
+enum A a;
+
+// CHECK:   cir.global external @a = #cir.int<0> : !u32i
+
+enum B : int;
+enum B b;
+
+// CHECK:   cir.global external @b = #cir.int<0> : !u32i
+
+
+enum C : int {
+  C_one,
+  C_two
+};
+enum C c;
+
+// CHECK:   cir.global external @c = #cir.int<0> : !u32i

clang/test/CIR/CodeGen/basic.cpp

@@ -102,6 +102,10 @@ size_type max_size() {
 // CHECK:   %3 = cir.cast(integral, %2 : !s32i), !u64i
 // CHECK:   %4 = cir.const #cir.int<8> : !u64i
 // CHECK:   %5 = cir.binop(div, %3, %4) : !u64i
+// CHECK:   cir.store %5, %0 : !u64i, !cir.ptr<!u64i>
+// CHECK:   %6 = cir.load %0 : !cir.ptr<!u64i>, !u64i
+// CHECK:   cir.return %6 : !u64i
+// CHECK:   }
 
 void ref_arg(int &x) {
   int y = x;
@@ -141,3 +145,29 @@ void ref_local(short x) {
 // CHECK:   %[[Y_REF_ADDR:.*]] = cir.alloca !cir.ptr<!s16i>, !cir.ptr<!cir.ptr<!s16i>>, ["y", init, const] {alignment = 8 : i64}
 // CHECK:   cir.store %[[ARG]], %[[X_ADDR]] : !s16i, !cir.ptr<!s16i>
 // CHECK:   cir.store %[[X_ADDR]], %[[Y_REF_ADDR]] : !cir.ptr<!s16i>, !cir.ptr<!cir.ptr<!s16i>>
+
+enum A {
+  A_one,
+  A_two
+};
+enum A a;
+
+// CHECK:   cir.global external @a = #cir.int<0> : !u32i
+
+enum B : int;
+enum B b;
+
+// CHECK:   cir.global external @b = #cir.int<0> : !s32i
+
+enum C : int {
+  C_one,
+  C_two
+};
+enum C c;
+
+// CHECK:   cir.global external @c = #cir.int<0> : !s32i
+
+enum class D : int;
+enum D d;
+
+// CHECK:   cir.global external @d = #cir.int<0> : !s32i