[OpenMP][OpenACC] Implement `ompx_hold` map type modifier extension in Clang (1/2)

This patch implements Clang support for an original OpenMP extension
we have developed to support OpenACC: the `ompx_hold` map type
modifier.  The next patch in this series, D106510, implements OpenMP
runtime support.

Consider the following example:

```
 #pragma omp target data map(ompx_hold, tofrom: x) // holds onto mapping of x
 {
   foo(); // might have map(delete: x)
   #pragma omp target map(present, alloc: x) // x is guaranteed to be present
   printf("%d\n", x);
 }
```

The `ompx_hold` map type modifier above specifies that the `target
data` directive holds onto the mapping for `x` throughout the
associated region regardless of any `target exit data` directives
executed during the call to `foo`.  Thus, the presence assertion for
`x` at the enclosed `target` construct cannot fail.  (As usual, the
standard OpenMP reference count for `x` must also reach zero before
the data is unmapped.)

Justification for inclusion in Clang and LLVM's OpenMP runtime:

* The `ompx_hold` modifier supports OpenACC functionality (structured
  reference count) that cannot be achieved in standard OpenMP, as of
  5.1.
* The runtime implementation for `ompx_hold` (next patch) will thus be
  used by Flang's OpenACC support.
* The Clang implementation for `ompx_hold` (this patch) as well as the
  runtime implementation are required for the Clang OpenACC support
  being developed as part of the ECP Clacc project, which translates
  OpenACC to OpenMP at the directive AST level.  These patches are the
  first step in upstreaming OpenACC functionality from Clacc.
* The Clang implementation for `ompx_hold` is also used by the tests
  in the runtime implementation.  That syntactic support makes the
  tests more readable than low-level runtime calls can.  Moreover,
  upstream Flang and Clang do not yet support OpenACC syntax
  sufficiently for writing the tests.
* More generally, the Clang implementation enables a clean separation
  of concerns between OpenACC and OpenMP development in LLVM.  That
  is, LLVM's OpenMP developers can discuss, modify, and debug LLVM's
  extended OpenMP implementation and test suite without directly
  considering OpenACC's language and execution model, which can be
  handled by LLVM's OpenACC developers.
* OpenMP users might find the `ompx_hold` modifier useful, as in the
  above example.

See new documentation introduced by this patch in `openmp/docs` for
more detail on the functionality of this extension and its
relationship with OpenACC.  For example, it explains how the runtime
must support two reference counts, as specified by OpenACC.

Clang recognizes `ompx_hold` unless `-fno-openmp-extensions`, a new
command-line option introduced by this patch, is specified.

Reviewed By: ABataev, jdoerfert, protze.joachim, grokos

Differential Revision: https://reviews.llvm.org/D106509

1 files changed, 23 insertions, 29 deletions

diff --git a/clang/lib/Parse/ParseOpenMP.cpp b/clang/lib/Parse/ParseOpenMP.cpp
index 18e43c3..a45168d 100644
--- a/clang/lib/Parse/ParseOpenMP.cpp
+++ b/clang/lib/Parse/ParseOpenMP.cpp
@@ -1651,7 +1651,7 @@ parseOpenMPSimpleClause(Parser &P, OpenMPClauseKind Kind) {
 
   unsigned Type = getOpenMPSimpleClauseType(
       Kind, Tok.isAnnotation() ? "" : P.getPreprocessor().getSpelling(Tok),
-      P.getLangOpts().OpenMP);
+      P.getLangOpts());
   SourceLocation TypeLoc = Tok.getLocation();
   if (Tok.isNot(tok::r_paren) && Tok.isNot(tok::comma) &&
       Tok.isNot(tok::annot_pragma_openmp_end))
@@ -3310,8 +3310,7 @@ OMPClause *Parser::ParseOpenMPSingleExprWithArgClause(OpenMPDirectiveKind DKind,
     Arg[Modifier2] = OMPC_SCHEDULE_MODIFIER_unknown;
     Arg[ScheduleKind] = OMPC_SCHEDULE_unknown;
     unsigned KindModifier = getOpenMPSimpleClauseType(
-        Kind, Tok.isAnnotation() ? "" : PP.getSpelling(Tok),
-        getLangOpts().OpenMP);
+        Kind, Tok.isAnnotation() ? "" : PP.getSpelling(Tok), getLangOpts());
     if (KindModifier > OMPC_SCHEDULE_unknown) {
       // Parse 'modifier'
       Arg[Modifier1] = KindModifier;
@@ -3323,8 +3322,7 @@ OMPClause *Parser::ParseOpenMPSingleExprWithArgClause(OpenMPDirectiveKind DKind,
         // Parse ',' 'modifier'
         ConsumeAnyToken();
         KindModifier = getOpenMPSimpleClauseType(
-            Kind, Tok.isAnnotation() ? "" : PP.getSpelling(Tok),
-            getLangOpts().OpenMP);
+            Kind, Tok.isAnnotation() ? "" : PP.getSpelling(Tok), getLangOpts());
         Arg[Modifier2] = KindModifier > OMPC_SCHEDULE_unknown
                              ? KindModifier
                              : (unsigned)OMPC_SCHEDULE_unknown;
@@ -3339,8 +3337,7 @@ OMPClause *Parser::ParseOpenMPSingleExprWithArgClause(OpenMPDirectiveKind DKind,
       else
         Diag(Tok, diag::warn_pragma_expected_colon) << "schedule modifier";
       KindModifier = getOpenMPSimpleClauseType(
-          Kind, Tok.isAnnotation() ? "" : PP.getSpelling(Tok),
-          getLangOpts().OpenMP);
+          Kind, Tok.isAnnotation() ? "" : PP.getSpelling(Tok), getLangOpts());
     }
     Arg[ScheduleKind] = KindModifier;
     KLoc[ScheduleKind] = Tok.getLocation();
@@ -3354,8 +3351,7 @@ OMPClause *Parser::ParseOpenMPSingleExprWithArgClause(OpenMPDirectiveKind DKind,
       DelimLoc = ConsumeAnyToken();
   } else if (Kind == OMPC_dist_schedule) {
     Arg.push_back(getOpenMPSimpleClauseType(
-        Kind, Tok.isAnnotation() ? "" : PP.getSpelling(Tok),
-        getLangOpts().OpenMP));
+        Kind, Tok.isAnnotation() ? "" : PP.getSpelling(Tok), getLangOpts()));
     KLoc.push_back(Tok.getLocation());
     if (Tok.isNot(tok::r_paren) && Tok.isNot(tok::comma) &&
         Tok.isNot(tok::annot_pragma_openmp_end))
@@ -3365,8 +3361,7 @@ OMPClause *Parser::ParseOpenMPSingleExprWithArgClause(OpenMPDirectiveKind DKind,
   } else if (Kind == OMPC_defaultmap) {
     // Get a defaultmap modifier
     unsigned Modifier = getOpenMPSimpleClauseType(
-        Kind, Tok.isAnnotation() ? "" : PP.getSpelling(Tok),
-        getLangOpts().OpenMP);
+        Kind, Tok.isAnnotation() ? "" : PP.getSpelling(Tok), getLangOpts());
     // Set defaultmap modifier to unknown if it is either scalar, aggregate, or
     // pointer
     if (Modifier < OMPC_DEFAULTMAP_MODIFIER_unknown)
@@ -3384,8 +3379,7 @@ OMPClause *Parser::ParseOpenMPSingleExprWithArgClause(OpenMPDirectiveKind DKind,
         Diag(Tok, diag::warn_pragma_expected_colon) << "defaultmap modifier";
       // Get a defaultmap kind
       Arg.push_back(getOpenMPSimpleClauseType(
-          Kind, Tok.isAnnotation() ? "" : PP.getSpelling(Tok),
-          getLangOpts().OpenMP));
+          Kind, Tok.isAnnotation() ? "" : PP.getSpelling(Tok), getLangOpts()));
       KLoc.push_back(Tok.getLocation());
       if (Tok.isNot(tok::r_paren) && Tok.isNot(tok::comma) &&
           Tok.isNot(tok::annot_pragma_openmp_end))
@@ -3400,8 +3394,7 @@ OMPClause *Parser::ParseOpenMPSingleExprWithArgClause(OpenMPDirectiveKind DKind,
         NextToken().is(tok::colon)) {
       // Parse optional <device modifier> ':'
       Arg.push_back(getOpenMPSimpleClauseType(
-          Kind, Tok.isAnnotation() ? "" : PP.getSpelling(Tok),
-          getLangOpts().OpenMP));
+          Kind, Tok.isAnnotation() ? "" : PP.getSpelling(Tok), getLangOpts()));
       KLoc.push_back(Tok.getLocation());
       ConsumeAnyToken();
       // Parse ':'
@@ -3512,7 +3505,7 @@ static OpenMPMapModifierKind isMapModifier(Parser &P) {
   Preprocessor &PP = P.getPreprocessor();
   OpenMPMapModifierKind TypeModifier =
       static_cast<OpenMPMapModifierKind>(getOpenMPSimpleClauseType(
-          OMPC_map, PP.getSpelling(Tok), P.getLangOpts().OpenMP));
+          OMPC_map, PP.getSpelling(Tok), P.getLangOpts()));
   return TypeModifier;
 }
 
@@ -3554,7 +3547,8 @@ bool Parser::parseMapTypeModifiers(OpenMPVarListDataTy &Data) {
     OpenMPMapModifierKind TypeModifier = isMapModifier(*this);
     if (TypeModifier == OMPC_MAP_MODIFIER_always ||
         TypeModifier == OMPC_MAP_MODIFIER_close ||
-        TypeModifier == OMPC_MAP_MODIFIER_present) {
+        TypeModifier == OMPC_MAP_MODIFIER_present ||
+        TypeModifier == OMPC_MAP_MODIFIER_ompx_hold) {
       Data.MapTypeModifiers.push_back(TypeModifier);
       Data.MapTypeModifiersLoc.push_back(Tok.getLocation());
       ConsumeToken();
@@ -3577,7 +3571,8 @@ bool Parser::parseMapTypeModifiers(OpenMPVarListDataTy &Data) {
       if (PP.LookAhead(0).is(tok::colon))
         return false;
       Diag(Tok, diag::err_omp_unknown_map_type_modifier)
-          << (getLangOpts().OpenMP >= 51 ? 1 : 0);
+          << (getLangOpts().OpenMP >= 51 ? 1 : 0)
+          << getLangOpts().OpenMPExtensions;
       ConsumeToken();
     }
     if (getCurToken().is(tok::comma))
@@ -3596,7 +3591,7 @@ static OpenMPMapClauseKind isMapType(Parser &P) {
   Preprocessor &PP = P.getPreprocessor();
   OpenMPMapClauseKind MapType =
       static_cast<OpenMPMapClauseKind>(getOpenMPSimpleClauseType(
-          OMPC_map, PP.getSpelling(Tok), P.getLangOpts().OpenMP));
+          OMPC_map, PP.getSpelling(Tok), P.getLangOpts()));
   return MapType;
 }
 
@@ -3749,8 +3744,8 @@ bool Parser::ParseOpenMPVarList(OpenMPDirectiveKind DKind,
         (Tok.is(tok::identifier) || Tok.is(tok::kw_default)) &&
         NextToken().is(tok::comma)) {
       // Parse optional reduction modifier.
-      Data.ExtraModifier = getOpenMPSimpleClauseType(Kind, PP.getSpelling(Tok),
-                                                     getLangOpts().OpenMP);
+      Data.ExtraModifier =
+          getOpenMPSimpleClauseType(Kind, PP.getSpelling(Tok), getLangOpts());
       Data.ExtraModifierLoc = Tok.getLocation();
       ConsumeToken();
       assert(Tok.is(tok::comma) && "Expected comma.");
@@ -3796,7 +3791,7 @@ bool Parser::ParseOpenMPVarList(OpenMPDirectiveKind DKind,
     ColonProtectionRAIIObject ColonRAII(*this);
     Data.ExtraModifier = getOpenMPSimpleClauseType(
         Kind, Tok.is(tok::identifier) ? PP.getSpelling(Tok) : "",
-        getLangOpts().OpenMP);
+        getLangOpts());
     Data.ExtraModifierLoc = Tok.getLocation();
     if (Data.ExtraModifier == OMPC_DEPEND_unknown) {
       SkipUntil(tok::colon, tok::r_paren, tok::annot_pragma_openmp_end,
@@ -3821,8 +3816,8 @@ bool Parser::ParseOpenMPVarList(OpenMPDirectiveKind DKind,
     // Try to parse modifier if any.
     Data.ExtraModifier = OMPC_LINEAR_val;
     if (Tok.is(tok::identifier) && PP.LookAhead(0).is(tok::l_paren)) {
-      Data.ExtraModifier = getOpenMPSimpleClauseType(Kind, PP.getSpelling(Tok),
-                                                     getLangOpts().OpenMP);
+      Data.ExtraModifier =
+          getOpenMPSimpleClauseType(Kind, PP.getSpelling(Tok), getLangOpts());
       Data.ExtraModifierLoc = ConsumeToken();
       LinearT.consumeOpen();
       NeedRParenForLinear = true;
@@ -3835,8 +3830,8 @@ bool Parser::ParseOpenMPVarList(OpenMPDirectiveKind DKind,
     if ((getLangOpts().OpenMP >= 50 && !isOpenMPDistributeDirective(DKind) &&
          !isOpenMPTaskLoopDirective(DKind)) &&
         Tok.is(tok::identifier) && PP.LookAhead(0).is(tok::colon)) {
-      Data.ExtraModifier = getOpenMPSimpleClauseType(Kind, PP.getSpelling(Tok),
-                                                     getLangOpts().OpenMP);
+      Data.ExtraModifier =
+          getOpenMPSimpleClauseType(Kind, PP.getSpelling(Tok), getLangOpts());
       Data.ExtraModifierLoc = Tok.getLocation();
       ConsumeToken();
       assert(Tok.is(tok::colon) && "Expected colon.");
@@ -3879,9 +3874,8 @@ bool Parser::ParseOpenMPVarList(OpenMPDirectiveKind DKind,
       Data.ColonLoc = ConsumeToken();
   } else if (Kind == OMPC_to || Kind == OMPC_from) {
     while (Tok.is(tok::identifier)) {
-      auto Modifier =
-          static_cast<OpenMPMotionModifierKind>(getOpenMPSimpleClauseType(
-              Kind, PP.getSpelling(Tok), getLangOpts().OpenMP));
+      auto Modifier = static_cast<OpenMPMotionModifierKind>(
+          getOpenMPSimpleClauseType(Kind, PP.getSpelling(Tok), getLangOpts()));
       if (Modifier == OMPC_MOTION_MODIFIER_unknown)
         break;
       Data.MotionModifiers.push_back(Modifier);