[LLVM][OpenMP] Add "version" parameter to getOpenMPDirectiveName (#139114)

Some OpenMP directives have different spellings in different versions of
the OpenMP spec. To use the proper spelling for a given spec version
pass "version" as a parameter to getOpenMPDirectiveName.

This parameter won't be used at the moment, and will have a default
value to allow callers not to pass it, for gradual adoption in various
components.

RFC:
https://discourse.llvm.org/t/rfc-alternative-spellings-of-openmp-directives/85507

Author: kparzysz

llvm/include/llvm/Frontend/OpenMP/OMP.h

@@ -47,6 +47,7 @@ static constexpr inline bool canHaveIterator(Clause C) {
   }
 }
 
+static constexpr unsigned FallbackVersion = 52;
 ArrayRef<unsigned> getOpenMPVersions();
 
 /// Create a nicer version of a function name for humans to look at.

llvm/unittests/Frontend/OpenMPDecompositionTest.cpp

@@ -188,7 +188,7 @@ struct StringifyClause {
   }
 
   static std::string to_str(llvm::omp::Directive D) {
-    return getOpenMPDirectiveName(D).str();
+    return getOpenMPDirectiveName(D, llvm::omp::FallbackVersion).str();
   }
   static std::string to_str(llvm::omp::Clause C) {
     return getOpenMPClauseName(C).str();
@@ -279,7 +279,7 @@ struct StringifyClause {
 std::string stringify(const omp::DirectiveWithClauses &DWC) {
   std::stringstream Stream;
 
-  Stream << getOpenMPDirectiveName(DWC.id).str();
+  Stream << getOpenMPDirectiveName(DWC.id, llvm::omp::FallbackVersion).str();
   for (const omp::Clause &C : DWC.clauses)
     Stream << ' ' << StringifyClause(C).Str;
 

llvm/unittests/Frontend/OpenMPParsingTest.cpp

@@ -23,11 +23,11 @@ TEST(OpenMPParsingTest, OpenMPDirectiveKind) {
 }
 
 TEST(OpenMPParsingTest, getOpenMPDirectiveName) {
-  EXPECT_EQ(getOpenMPDirectiveName(OMPD_unknown), "unknown");
+  EXPECT_EQ(getOpenMPDirectiveName(OMPD_unknown, FallbackVersion), "unknown");
 
-  EXPECT_EQ(getOpenMPDirectiveName(OMPD_for), "for");
-  EXPECT_EQ(getOpenMPDirectiveName(OMPD_simd), "simd");
-  EXPECT_EQ(getOpenMPDirectiveName(OMPD_for_simd), "for simd");
+  EXPECT_EQ(getOpenMPDirectiveName(OMPD_for, FallbackVersion), "for");
+  EXPECT_EQ(getOpenMPDirectiveName(OMPD_simd, FallbackVersion), "simd");
+  EXPECT_EQ(getOpenMPDirectiveName(OMPD_for_simd, FallbackVersion), "for simd");
 }
 
 TEST(OpenMPParsingTest, getOpenMPClauseKind) {

llvm/utils/TableGen/Basic/DirectiveEmitter.cpp

@@ -244,8 +244,13 @@ static void emitDirectivesDecl(const RecordKeeper &Records, raw_ostream &OS) {
   OS << "LLVM_ABI Directive get" << DirLang.getName()
      << "DirectiveKind(llvm::StringRef Str);\n";
   OS << "\n";
+  // For OpenMP the signature is
+  //   getOpenMPDirectiveName(Directive D, unsigned V)
   OS << "LLVM_ABI llvm::StringRef get" << DirLang.getName()
-     << "DirectiveName(Directive D);\n";
+     << "DirectiveName(Directive D";
+  if (DirLang.getCppNamespace() == "omp")
+    OS << ", unsigned = 0";
+  OS << ");\n";
   OS << "\n";
   OS << "LLVM_ABI Clause get" << DirLang.getName()
      << "ClauseKind(llvm::StringRef Str);\n";
@@ -280,9 +285,14 @@ static void emitDirectivesDecl(const RecordKeeper &Records, raw_ostream &OS) {
 static void generateGetName(ArrayRef<const Record *> Records, raw_ostream &OS,
                             StringRef Enum, const DirectiveLanguage &DirLang,
                             StringRef Prefix) {
+  // For OpenMP the "Directive" signature is
+  //   getOpenMPDirectiveName(Directive D, unsigned V)
   OS << "\n";
   OS << "llvm::StringRef llvm::" << DirLang.getCppNamespace() << "::get"
-     << DirLang.getName() << Enum << "Name(" << Enum << " Kind) {\n";
+     << DirLang.getName() << Enum << "Name(" << Enum << " Kind";
+  if (DirLang.getCppNamespace() == "omp" && Enum == "Directive")
+    OS << ", unsigned";
+  OS << ") {\n";
   OS << "  switch (Kind) {\n";
   for (const BaseRecord Rec : Records) {
     OS << "    case " << Prefix << Rec.getFormattedName() << ":\n";