[clang][OpenMP] 6.0: Add defaultmap implicit-behavior 'private'

Per OpenMP 6.0 specification, section 7.9.9

Argument keywords, page 291, L17
Semantics, page 292, L15-16
  The behavior of 'private' should be described in the same manner as that
  of 'firstprivate'

  15 ... If implicit-behavior is firstprivate, 16 the attribute is a
  data-sharing attribute of firstprivate.

  Relevant OpenMP 6.0 issues
    defaultmap clause new implicit-behavior 'private' should be documented
      OpenMP/spec#4571
    Issue 4571: Add missing sentence about private to defaultmap
      OpenMP/spec#4577

Testing:
  Updated 'defaultmap' error message and codegen LIT tests to verify
  behavior of 'private' in OpenMP 6.0.

Author: ddpagan

clang/docs/ReleaseNotes.rst

@@ -533,6 +533,7 @@ OpenMP Support
 - Properly handle array section/assumed-size array privatization in C/C++.
 - Added support for ``variable-category`` modifier in ``default clause``.
 - Added support for ``defaultmap`` directive implicit-behavior ``storage``.
+- Added support for ``defaultmap`` directive implicit-behavior ``private``.
 
 Improvements
 ^^^^^^^^^^^^

clang/include/clang/Basic/OpenMPKinds.def

@@ -138,6 +138,7 @@ OPENMP_DEFAULTMAP_MODIFIER(none)
 OPENMP_DEFAULTMAP_MODIFIER(default)
 OPENMP_DEFAULTMAP_MODIFIER(present)
 OPENMP_DEFAULTMAP_MODIFIER(storage)
+OPENMP_DEFAULTMAP_MODIFIER(private)
 
 // Static attributes for 'depend' clause.
 OPENMP_DEPEND_KIND(in)

clang/lib/Basic/OpenMPKinds.cpp

@@ -118,7 +118,8 @@ unsigned clang::getOpenMPSimpleClauseType(OpenMPClauseKind Kind, StringRef Str,
   .Case(#Name, static_cast<unsigned>(OMPC_DEFAULTMAP_MODIFIER_##Name))
 #include "clang/Basic/OpenMPKinds.def"
                         .Default(OMPC_DEFAULTMAP_unknown);
-    if (LangOpts.OpenMP < 60 && Type == OMPC_DEFAULTMAP_MODIFIER_storage)
+    if (LangOpts.OpenMP < 60 && (Type == OMPC_DEFAULTMAP_MODIFIER_storage ||
+                                 Type == OMPC_DEFAULTMAP_MODIFIER_private))
       return OMPC_DEFAULTMAP_MODIFIER_unknown;
     return Type;
   }

clang/lib/Sema/SemaOpenMP.cpp

@@ -3770,6 +3770,7 @@ getMapClauseKindFromModifier(OpenMPDefaultmapClauseModifier M,
     Kind = OMPC_MAP_alloc;
     break;
   case OMPC_DEFAULTMAP_MODIFIER_firstprivate:
+  case OMPC_DEFAULTMAP_MODIFIER_private:
   case OMPC_DEFAULTMAP_MODIFIER_last:
     llvm_unreachable("Unexpected defaultmap implicit behavior");
   case OMPC_DEFAULTMAP_MODIFIER_none:
@@ -4006,9 +4007,13 @@ class DSAAttrChecker final : public StmtVisitor<DSAAttrChecker, void> {
           } else {
             OpenMPDefaultmapClauseModifier M =
                 Stack->getDefaultmapModifier(ClauseKind);
-            OpenMPMapClauseKind Kind = getMapClauseKindFromModifier(
-                M, ClauseKind == OMPC_DEFAULTMAP_aggregate || Res);
-            ImpInfo.Mappings[ClauseKind][Kind].insert(E);
+            if (M == OMPC_DEFAULTMAP_MODIFIER_private) {
+              ImpInfo.Privates.insert(E);
+            } else {
+              OpenMPMapClauseKind Kind = getMapClauseKindFromModifier(
+                  M, ClauseKind == OMPC_DEFAULTMAP_aggregate || Res);
+              ImpInfo.Mappings[ClauseKind][Kind].insert(E);
+            }
           }
           return;
         }
@@ -23118,7 +23123,7 @@ OMPClause *SemaOpenMP::ActOnOpenMPDefaultmapClause(
                 ? "'alloc', 'from', 'to', 'tofrom', "
                   "'firstprivate', 'none', 'default', 'present'"
                 : "'storage', 'from', 'to', 'tofrom', "
-                  "'firstprivate', 'none', 'default', 'present'";
+                  "'firstprivate', 'private', 'none', 'default', 'present'";
         if (!isDefaultmapKind && isDefaultmapModifier) {
           Diag(KindLoc, diag::err_omp_unexpected_clause_value)
               << KindValue << getOpenMPClauseNameForDiag(OMPC_defaultmap);