[CIR] Backport UnaryDeref support for ComplexType (#1825)

Backport UnaryDeref support for ComplexType from the upstream

Author: AmrDeveloper

clang/lib/CIR/CodeGen/CIRGenExprComplex.cpp

@@ -147,7 +147,7 @@ class ComplexExprEmitter : public StmtVisitor<ComplexExprEmitter, mlir::Value> {
   mlir::Value VisitUnaryPreInc(const UnaryOperator *E) {
     return VisitPrePostIncDec(E, true, true);
   }
-  mlir::Value VisitUnaryDeref(const Expr *E) { llvm_unreachable("NYI"); }
+  mlir::Value VisitUnaryDeref(const Expr *E) { return emitLoadOfLValue(E); }
 
   mlir::Value VisitUnaryPlus(const UnaryOperator *E,
                              QualType PromotionType = QualType());

clang/test/CIR/CodeGen/complex.cpp

@@ -15,6 +15,22 @@ void complex_functional_cast() {
 // LLVM: %[[INIT:.*]] = alloca { i32, i32 }, i64 1, align 4
 // LLVM: store { i32, i32 } zeroinitializer, ptr %[[INIT]], align 4
 
+void complex_deref_expr(int _Complex* a) {
+  int _Complex b = *a;
+}
+
+// CIR: %[[COMPLEX_A_PTR:.*]] = cir.alloca !cir.ptr<!cir.complex<!s32i>>, !cir.ptr<!cir.ptr<!cir.complex<!s32i>>>, ["a", init]
+// CIR: %[[COMPLEX_B:.*]] = cir.alloca !cir.complex<!s32i>, !cir.ptr<!cir.complex<!s32i>>, ["b", init]
+// CIR: %[[COMPLEX_A:.*]] = cir.load deref {{.*}} %[[COMPLEX_A_PTR]] : !cir.ptr<!cir.ptr<!cir.complex<!s32i>>>, !cir.ptr<!cir.complex<!s32i>>
+// CIR: %[[TMP:.*]] = cir.load{{.*}} %[[COMPLEX_A]] : !cir.ptr<!cir.complex<!s32i>>, !cir.complex<!s32i>
+// CIR: cir.store{{.*}} %[[TMP]], %[[COMPLEX_B]] : !cir.complex<!s32i>, !cir.ptr<!cir.complex<!s32i>>
+
+// LLVM: %[[COMPLEX_A_PTR:.*]] = alloca ptr, i64 1, align 8
+// LLVM: %[[COMPLEX_B:.*]] = alloca { i32, i32 }, i64 1, align 4
+// LLVM: %[[COMPLEX_A:.*]] = load ptr, ptr %[[COMPLEX_A_PTR]], align 8
+// LLVM: %[[TMP:.*]] = load { i32, i32 }, ptr %[[COMPLEX_A]], align 4
+// LLVM: store { i32, i32 } %[[TMP]], ptr %[[COMPLEX_B]], align 4
+
 void complex_cxx_scalar_value_init_expr() {
   using IntComplex = int _Complex;
   int _Complex a = IntComplex();