[flang-commits] [flang] [flang][openmp]Add UserReductionDetails and use in DECLARE REDUCTION (PR #131628)

[Kiran Chandramohan via flang-commits]

================
@@ -1748,14 +1749,75 @@ void OmpVisitor::ProcessMapperSpecifier(const parser::OmpMapperSpecifier &spec,
   PopScope();
 }
 
+parser::CharBlock MakeNameFromOperator(
+    const parser::DefinedOperator::IntrinsicOperator &op) {
+  switch (op) {
+  case parser::DefinedOperator::IntrinsicOperator::Multiply:
+    return parser::CharBlock{"op.*", 4};
+  case parser::DefinedOperator::IntrinsicOperator::Add:
+    return parser::CharBlock{"op.+", 4};
+  case parser::DefinedOperator::IntrinsicOperator::Subtract:
+    return parser::CharBlock{"op.-", 4};
+
+  case parser::DefinedOperator::IntrinsicOperator::AND:
+    return parser::CharBlock{"op.AND", 6};
+  case parser::DefinedOperator::IntrinsicOperator::OR:
+    return parser::CharBlock{"op.OR", 6};
+  case parser::DefinedOperator::IntrinsicOperator::EQV:
+    return parser::CharBlock{"op.EQV", 7};
+  case parser::DefinedOperator::IntrinsicOperator::NEQV:
+    return parser::CharBlock{"op.NEQV", 8};
+
+  default:
+    DIE("Unsupported operator...");
+    return parser::CharBlock{"op.?", 4};
+  }
+}
+
+parser::CharBlock MangleSpecialFunctions(const parser::CharBlock name) {
+  return llvm::StringSwitch<parser::CharBlock>(name.ToString())
+      .Case("max", {"op.max", 6})
+      .Case("min", {"op.min", 6})
+      .Case("iand", {"op.iand", 7})
+      .Case("ior", {"op.ior", 6})
+      .Case("ieor", {"op.ieor", 7})
+      .Default(name);
+}
+
 void OmpVisitor::ProcessReductionSpecifier(
     const parser::OmpReductionSpecifier &spec,
     const std::optional<parser::OmpClauseList> &clauses) {
+  const parser::Name *name{nullptr};
+  parser::Name mangledName;
+  UserReductionDetails reductionDetailsTemp;
   const auto &id{std::get<parser::OmpReductionIdentifier>(spec.t)};
   if (auto procDes{std::get_if<parser::ProcedureDesignator>(&id.u)}) {
-    if (auto *name{std::get_if<parser::Name>(&procDes->u)}) {
-      name->symbol =
-          &MakeSymbol(*name, MiscDetails{MiscDetails::Kind::ConstructName});
+    name = std::get_if<parser::Name>(&procDes->u);
+    if (name) {
+      mangledName.source = MangleSpecialFunctions(name->source);
+    }
+  } else {
+    const auto &defOp{std::get<parser::DefinedOperator>(id.u)};
+    mangledName.source = MakeNameFromOperator(
+        std::get<parser::DefinedOperator::IntrinsicOperator>(defOp.u));
+    name = &mangledName;
+  }
+
+  // Use reductionDetailsTemp if we can't find the symbol (this is
+  // the first, or only, instance with this name). The details then
+  // gets stored in the symbol when it's created.
+  UserReductionDetails *reductionDetails{&reductionDetailsTemp};
+  Symbol *symbol{FindSymbol(mangledName)};
+  if (symbol) {
+    // If we found a symbol, we append the type info to the
+    // existing reductionDetails.
+    reductionDetails = symbol->detailsIf<UserReductionDetails>();
+
+    if (!reductionDetails) {
+      context().Say(name->source,
+          "Duplicate defineition of '%s' in !$OMP DECLARE REDUCTION"_err_en_US,
----------------
kiranchandramohan wrote:

```suggestion
          "Duplicate definition of '%s' in DECLARE REDUCTION"_err_en_US,
```

https://github.com/llvm/llvm-project/pull/131628