[CIR] Implement CK_LValueToRValueBitCast for ComplexType (#1751)

Implement supporting for CK_LValueToRValueBitCast for ComplexType

Author: AmrDeveloper

clang/lib/CIR/CodeGen/CIRGenExprComplex.cpp

@@ -431,8 +431,14 @@ mlir::Value ComplexExprEmitter::emitCast(CastKind CK, Expr *Op,
   case CK_LValueBitCast:
     llvm_unreachable("NYI");
 
-  case CK_LValueToRValueBitCast:
-    llvm_unreachable("NYI");
+  case CK_LValueToRValueBitCast: {
+    LValue SourceLVal = CGF.emitLValue(Op);
+    Address Addr = SourceLVal.getAddress().withElementType(
+        Builder, CGF.convertTypeForMem(DestTy));
+    LValue DestLV = CGF.makeAddrLValue(Addr, DestTy);
+    DestLV.setTBAAInfo(TBAAAccessInfo::getMayAliasInfo());
+    return emitLoadOfLValue(DestLV, Op->getExprLoc());
+  }
 
   case CK_BitCast:
   case CK_BaseToDerived:

clang/test/CIR/CodeGen/complex-cast.c

@@ -199,6 +199,29 @@ void complex_to_bool() {
 
 // CHECK: }
 
+struct CX {
+  double real;
+  double imag;
+};
+
+void lvalue_to_rvalue_bitcast() {
+   struct CX a;
+   double _Complex b = __builtin_bit_cast(double _Complex, a);
+}
+
+// CHECK-LABEL: @lvalue_to_rvalue_bitcast()
+
+// CIR-BEFORE: %{{.+}} = cir.cast(bitcast, %{{.+}} : !cir.ptr<!rec_CX>), !cir.ptr<!cir.complex<!cir.double>>
+
+// CIR-AFTER: %{{.+}} = cir.cast(bitcast, %{{.+}} : !cir.ptr<!rec_CX>), !cir.ptr<!cir.complex<!cir.double>>
+
+// LLVM: %[[PTR_ADDR:.*]] = alloca %struct.CX, i64 1, align 8
+// LLVM: %[[COMPLEX_ADDR:.*]] = alloca { double, double }, i64 1, align 8
+// LLVM: %[[PTR_TO_COMPLEX:.*]] = load { double, double }, ptr %[[PTR_ADDR]], align 8
+// LLVM: store { double, double } %[[PTR_TO_COMPLEX]], ptr %[[COMPLEX_ADDR]], align 8
+
+// CHECK: }
+
 void complex_to_complex_cast() {
   cd = cf;
   ci = cs;