[llvm-branch-commits] [flang] [flang][OpenMP] Parsing context selectors for METADIRECTIVE (PR #121815)

[Kiran Chandramohan via llvm-branch-commits]

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@@ -3474,6 +3477,138 @@ WRAPPER_CLASS(OmpObjectList, std::list<OmpObject>);
 
 #define MODIFIERS() std::optional<std::list<Modifier>>
 
+inline namespace traits {
+// trait-property-name ->
+//    identifier | string-literal
+struct OmpTraitPropertyName {
+  CharBlock source;
+  WRAPPER_CLASS_BOILERPLATE(OmpTraitPropertyName, std::string);
+};
+
+// trait-score ->
+//    SCORE(non-negative-const-integer-expression)
+struct OmpTraitScore {
+  CharBlock source;
+  WRAPPER_CLASS_BOILERPLATE(OmpTraitScore, ScalarIntExpr);
+};
+
+// trait-property-extension ->
+//    trait-property-name (trait-property-value, ...)
+// trait-property-value ->
+//    trait-property-name |
+//    scalar-integer-expression |
+//    trait-property-extension
+//
+// The grammar in OpenMP 5.2+ spec is ambiguous, the above is a different
+// version (but equivalent) that doesn't have ambiguities.
+// The ambiguity is in
+//   trait-property:
+//      trait-property-name          <- (a)
+//      trait-property-clause
+//      trait-property-expression    <- (b)
+//      trait-property-extension     <- this conflicts with (a) and (b)
+//   trait-property-extension:
+//      trait-property-name          <- conflict with (a)
+//      identifier(trait-property-extension[, trait-property-extension[, ...]])
+//      constant integer expression  <- conflict with (b)
+//
+struct OmpTraitPropertyExtension {
+  CharBlock source;
+  TUPLE_CLASS_BOILERPLATE(OmpTraitPropertyExtension);
+  struct ExtensionValue {
+    CharBlock source;
+    UNION_CLASS_BOILERPLATE(ExtensionValue);
+    std::variant<OmpTraitPropertyName, ScalarExpr,
+        common::Indirection<OmpTraitPropertyExtension>>
+        u;
+  };
+  using ExtensionList = std::list<ExtensionValue>;
+  std::tuple<OmpTraitPropertyName, ExtensionList> t;
+};
+
+// trait-property ->
+//    trait-property-name | OmpClause |
+//    trait-property-expression | trait-property-extension
+// trait-property-expression ->
+//    scalar-logical-expression | scalar-integer-expression
+//
+// The parser for a logical expression will accept an integer expression,
+// and if it's not logical, it will flag an error later. The same thing
+// will happen if the scalar integer expression sees a logical expresion.
+// To avoid this, parse all expressions as scalar expressions.
+struct OmpTraitProperty {
+  CharBlock source;
+  UNION_CLASS_BOILERPLATE(OmpTraitProperty);
+  std::variant<OmpTraitPropertyName, common::Indirection<OmpClause>,
+      ScalarExpr, // trait-property-expresion
+      OmpTraitPropertyExtension>
+      u;
+};
+
+// trait-selector-name ->
+//    KIND |              DT       // name-list (host, nohost, +/add-def-doc)
+//    ISA |               DT       // name-list (isa_name, ... /impl-defined)
+//    ARCH |              DT       // name-list (arch_name, ... /impl-defined)
+//    directive-name |    C        // no properties
+//    SIMD |              C        // clause-list (from declare_simd)
+//                                 // (at least simdlen, inbranch/notinbranch)
+//    DEVICE_NUM |        T        // device-number
+//    UID |               T        // unique-string-id /impl-defined
+//    VENDOR |            I        // name-list (vendor-id /add-def-doc)
+//    EXTENSION |         I        // name-list (ext_name /impl-defined)
+//    ATOMIC_DEFAULT_MEM_ORDER I | // value of admo
+//    REQUIRES |          I        // clause-list (from requires)
+//    CONDITION           U        // logical-expr
+//
+// Trait-set-selectors:
+//    [D]evice, [T]arget_device, [C]onstruct, [I]mplementation, [U]ser.
+struct OmpTraitSelectorName {
+  CharBlock source;
+  UNION_CLASS_BOILERPLATE(OmpTraitSelectorName);
+  ENUM_CLASS(Value, Arch, Atomic_Default_Mem_Order, Condition, Device_Num,
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kiranchandramohan wrote:

Are underscores generally used in this file?

https://github.com/llvm/llvm-project/pull/121815