[Flang][OpenMP] Use the ultimate symbol in a call to the IsPointer function

[kiranchandramohan]

Summary

The IsPointer check currently fails for host-associated symbols in OpenMP regions. This causes some failures in semantic checks for pointer association in an OpenMP region. Fix is to use the ultimate symbol in the call to the IsPointer function in CheckPointerAssignment
function in lib/Semantics/pointer-assignment.cpp.

This patch fixes the issue reported by Peixin in https://github.com/flang-compiler/f18-llvm-project/issues/1171#issuecomment-955180002.

[peixin]

Thanks @kiranchandramohan. LGTM. Please fix the code format warning.

BTW, this also fix the case when the pointer is in common block and the common block is in private clause.

Could you please cherry-pick this patch to fir-dev after merged? I need fix https://github.com/flang-compiler/f18-llvm-project/pull/1179 if this patch is merged since this patch affects the lowering of copying symbols in private clause.

[kiranchandramohan]

clang-format changes

[kiranchandramohan]

Use the ultimate symbol as argument to the IsPointer function in CheckPointerAssignment
function in lib/Semantics/pointer-assignment.cpp. As suggested by @klausler.

flang/lib/Semantics/pointer-assignment.cpp

 }
 
 bool CheckPointerAssignment(evaluate::FoldingContext &context,
     const SomeExpr &lhs, const SomeExpr &rhs, bool isBoundsRemapping) {
   const Symbol *pointer{GetLastSymbol(lhs)};
   if (!pointer) {
     return false; // error was reported
   }
-  if (!IsPointer(*pointer)) {
+  if (!IsPointer(pointer->GetUltimate())) {
     evaluate::SayWithDeclaration(context.messages(), *pointer,
         "'%s' is not a pointer"_err_en_US, pointer->name());
     return false;
   }
   if (pointer->has<ProcEntityDetails>() && evaluate::ExtractCoarrayRef(lhs)) {
     context.messages().Say( // C1027
         "Procedure pointer may not be a coindexed object"_err_en_US);
     return false;

flang/test/Semantics/omp-private-is-pointer-check.f90

+! RUN: %flang_fc1 -fopenmp -fsyntax-only %s
+
+subroutine s
+  integer, pointer :: p
+  integer, target :: t
+
+  !$omp parallel private(p)
+    p=>t
+  !$omp end parallel
+end subroutine