[flang][openacc] Add clause validity tests for the update directive

Add couple of clause validity tests for the update directive and check for
the restriction where at least self, host or device clause must appear on the directive.

Reviewed By: sameeranjoshi

Differential Revision: https://reviews.llvm.org/D92447

flang/lib/Semantics/check-acc-structure.cpp

@@ -201,6 +201,8 @@ void AccStructureChecker::Leave(const parser::OpenACCStandaloneConstruct &x) {
     CheckRequireAtLeastOneOf();
     break;
   case llvm::acc::Directive::ACCD_update:
+    // Restriction - line 2636
+    CheckRequireAtLeastOneOf();
     // Restriction - 2301
     CheckOnlyAllowedAfter(llvm::acc::Clause::ACCC_device_type,
         updateOnlyAllowedAfterDeviceTypeClauses);

flang/test/Semantics/acc-clause-validity.f90

@@ -138,9 +138,37 @@ program openacc_clause_validity
   !ERROR: Unmatched PARALLEL directive
   !$acc end parallel
 
+  !ERROR: At least one of DEVICE, HOST, SELF clause must appear on the UPDATE directive
+  !$acc update
+
   !$acc update self(a, f) host(g) device(h)
 
-  !$acc update device(i) device_type(*) async
+  !$acc update host(aa) async(1)
+
+  !$acc update device(bb) async(async1)
+
+  !ERROR: At most one ASYNC clause can appear on the UPDATE directive
+  !$acc update host(aa, bb) async(1) async(2)
+
+  !$acc update self(bb, cc(:)) wait(1)
+
+  !$acc update device(aa, bb, cc) wait(wait1)
+
+  !$acc update host(aa) host(bb) device(cc) wait(1,2)
+
+  !$acc update device(aa, cc) wait(wait1, wait2)
+
+  !$acc update device(aa) device_type(*) async
+
+  !$acc update host(bb) device_type(*) wait
+
+  !$acc update self(cc) device_type(1,2) async device_type(3) wait
+
+  !ERROR: At most one IF clause can appear on the UPDATE directive
+  !$acc update device(aa) if(.true.) if(ifCondition)
+
+  !ERROR: At most one IF_PRESENT clause can appear on the UPDATE directive
+  !$acc update device(bb) if_present if_present
 
   !ERROR: Clause IF is not allowed after clause DEVICE_TYPE on the UPDATE directive
   !$acc update device(i) device_type(*) if(.TRUE.)