[Flang][OpenMP] Consider renames when processing reduction intrinsics (#70822)

Fixes #68654

Depends on #70790

Author: kiranchandramohan

flang/lib/Lower/OpenMP.cpp

@@ -745,6 +745,9 @@ class ReductionProcessor {
       const Fortran::parser::ProcedureDesignator &pd) {
     const auto *name{Fortran::parser::Unwrap<Fortran::parser::Name>(pd)};
     assert(name && "Invalid Reduction Intrinsic.");
+    if (!name->symbol->GetUltimate().attrs().test(
+            Fortran::semantics::Attr::INTRINSIC))
+      return false;
     auto redType = llvm::StringSwitch<std::optional<IntrinsicProc>>(
                        getRealName(name).ToString())
                        .Case("max", IntrinsicProc::MAX)

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

@@ -2299,18 +2299,20 @@ bool OmpStructureChecker::CheckReductionOperators(
           },
           [&](const parser::ProcedureDesignator &procD) {
             const parser::Name *name{std::get_if<parser::Name>(&procD.u)};
-            if (name) {
-              if (name->source == "max" || name->source == "min" ||
-                  name->source == "iand" || name->source == "ior" ||
-                  name->source == "ieor") {
+            if (name && name->symbol) {
+              const SourceName &realName{name->symbol->GetUltimate().name()};
+              if (realName == "max" || realName == "min" ||
+                  realName == "iand" || realName == "ior" ||
+                  realName == "ieor") {
                 ok = true;
-              } else {
-                context_.Say(GetContext().clauseSource,
-                    "Invalid reduction identifier in REDUCTION "
-                    "clause."_err_en_US,
-                    ContextDirectiveAsFortran());
               }
             }
+            if (!ok) {
+              context_.Say(GetContext().clauseSource,
+                  "Invalid reduction identifier in REDUCTION "
+                  "clause."_err_en_US,
+                  ContextDirectiveAsFortran());
+            }
           },
       },
       definedOp.u);

flang/lib/Semantics/resolve-directives.cpp

@@ -481,21 +481,28 @@ class OmpAttributeVisitor : DirectiveAttributeVisitor<llvm::omp::Directive> {
   bool Pre(const parser::OmpClause::Reduction &x) {
     const parser::OmpReductionOperator &opr{
         std::get<parser::OmpReductionOperator>(x.v.t)};
+    auto createDummyProcSymbol = [&](const parser::Name *name) {
+      // If name resolution failed, create a dummy symbol
+      const auto namePair{
+          currScope().try_emplace(name->source, Attrs{}, ProcEntityDetails{})};
+      auto &newSymbol{*namePair.first->second};
+      name->symbol = &newSymbol;
+    };
     if (const auto *procD{parser::Unwrap<parser::ProcedureDesignator>(opr.u)}) {
       if (const auto *name{parser::Unwrap<parser::Name>(procD->u)}) {
         if (!name->symbol) {
-          const auto namePair{currScope().try_emplace(
-              name->source, Attrs{}, ProcEntityDetails{})};
-          auto &symbol{*namePair.first->second};
-          name->symbol = &symbol;
-          name->symbol->set(Symbol::Flag::OmpReduction);
-          AddToContextObjectWithDSA(*name->symbol, Symbol::Flag::OmpReduction);
+          if (!ResolveName(name)) {
+            createDummyProcSymbol(name);
+          }
         }
       }
       if (const auto *procRef{
               parser::Unwrap<parser::ProcComponentRef>(procD->u)}) {
-        ResolveOmp(*procRef->v.thing.component.symbol,
-            Symbol::Flag::OmpReduction, currScope());
+        if (!procRef->v.thing.component.symbol) {
+          if (!ResolveName(&procRef->v.thing.component)) {
+            createDummyProcSymbol(&procRef->v.thing.component);
+          }
+        }
       }
     }
     const auto &objList{std::get<parser::OmpObjectList>(x.v.t)};

flang/test/Lower/OpenMP/wsloop-reduction-max-2.f90

@@ -0,0 +1,19 @@
+! RUN: bbc -emit-hlfir -fopenmp -o - %s 2>&1 | FileCheck %s
+! RUN: %flang_fc1 -emit-hlfir -fopenmp -o - %s 2>&1 | FileCheck %s
+
+! CHECK: omp.wsloop reduction(@max_i_32
+! CHECK: omp.reduction
+
+module m1
+  intrinsic max
+end module m1
+program main
+  use m1, ren=>max
+  n=0
+  !$omp parallel do reduction(ren:n)
+  do i=1,100
+     n=max(n,i)
+  end do
+  if (n/=100) print *,101
+  print *,'pass'
+end program main