[CIR] Use ZeroAttr as zeroinitializer for ComplexType (#148033)

Use ZeroAttr as a zeroinitializer for ComplexType, similar to what we
did in CXXScalarValueInitExpr

#141365

Author: AmrDeveloper

clang/lib/CIR/CodeGen/CIRGenExprComplex.cpp

@@ -291,12 +291,8 @@ mlir::Value ComplexExprEmitter::VisitInitListExpr(const InitListExpr *e) {
   }
 
   assert(e->getNumInits() == 0 && "Unexpected number of inits");
-  QualType complexElemTy =
-      e->getType()->castAs<clang::ComplexType>()->getElementType();
-  mlir::Type complexElemLLVMTy = cgf.convertType(complexElemTy);
-  mlir::TypedAttr defaultValue = builder.getZeroInitAttr(complexElemLLVMTy);
-  auto complexAttr = cir::ConstComplexAttr::get(defaultValue, defaultValue);
-  return builder.create<cir::ConstantOp>(loc, complexAttr);
+  mlir::Type complexTy = cgf.convertType(e->getType());
+  return builder.getNullValue(complexTy, loc);
 }
 
 mlir::Value

clang/test/CIR/CodeGen/complex.cpp

@@ -31,7 +31,7 @@ float _Complex cf2 = { 1.0f, 2.0f };
 void foo() { int _Complex c = {}; }
 
 // CIR: %[[INIT:.*]] = cir.alloca !cir.complex<!s32i>, !cir.ptr<!cir.complex<!s32i>>, ["c", init]
-// CIR: %[[COMPLEX:.*]] = cir.const #cir.const_complex<#cir.int<0> : !s32i, #cir.int<0> : !s32i> : !cir.complex<!s32i>
+// CIR: %[[COMPLEX:.*]] = cir.const #cir.zero : !cir.complex<!s32i>
 // CIR: cir.store{{.*}} %[[COMPLEX]], %[[INIT]] : !cir.complex<!s32i>, !cir.ptr<!cir.complex<!s32i>>
 
 // LLVM: %[[INIT:.*]] = alloca { i32, i32 }, i64 1, align 4
@@ -741,7 +741,7 @@ void foo29() {
 }
 
 // CIR: %[[INIT:.*]] = cir.alloca !cir.complex<!s32i>, !cir.ptr<!cir.complex<!s32i>>, ["a", init]
-// CIR: %[[COMPLEX:.*]] = cir.const #cir.const_complex<#cir.int<0> : !s32i, #cir.int<0> : !s32i> : !cir.complex<!s32i>
+// CIR: %[[COMPLEX:.*]] = cir.const #cir.zero : !cir.complex<!s32i>
 // CIR: cir.store{{.*}} %[[COMPLEX]], %[[INIT]] : !cir.complex<!s32i>, !cir.ptr<!cir.complex<!s32i>>
 
 // LLVM: %[[INIT:.*]] = alloca { i32, i32 }, i64 1, align 4