[Clang][OpenMP][LoopTransformations] Implement "#pragma omp fuse" loop transformation directive and "looprange" clause (#139293)

This change implements the fuse directive, `#pragma omp fuse`, as specified in the OpenMP 6.0, along with the `looprange` clause in clang.

This change also adds minimal stubs so flang keeps compiling (a full implementation in flang of this directive is still pending).

---------

Co-authored-by: Roger Ferrer Ibanez <roger.ferrer@bsc.es>

1 files changed, 36 insertions, 0 deletions

diff --git a/clang/lib/Parse/ParseOpenMP.cpp b/clang/lib/Parse/ParseOpenMP.cpp
index 02f3f10..04f29c8 100644
--- a/clang/lib/Parse/ParseOpenMP.cpp
+++ b/clang/lib/Parse/ParseOpenMP.cpp
@@ -2968,6 +2968,39 @@ OMPClause *Parser::ParseOpenMPSizesClause() {
                                                  OpenLoc, CloseLoc);
 }
 
+OMPClause *Parser::ParseOpenMPLoopRangeClause() {
+  SourceLocation ClauseNameLoc = ConsumeToken();
+  SourceLocation FirstLoc, CountLoc;
+
+  BalancedDelimiterTracker T(*this, tok::l_paren, tok::annot_pragma_openmp_end);
+  if (T.consumeOpen()) {
+    Diag(Tok, diag::err_expected) << tok::l_paren;
+    return nullptr;
+  }
+
+  FirstLoc = Tok.getLocation();
+  ExprResult FirstVal = ParseConstantExpression();
+  if (!FirstVal.isUsable()) {
+    T.skipToEnd();
+    return nullptr;
+  }
+
+  ExpectAndConsume(tok::comma);
+
+  CountLoc = Tok.getLocation();
+  ExprResult CountVal = ParseConstantExpression();
+  if (!CountVal.isUsable()) {
+    T.skipToEnd();
+    return nullptr;
+  }
+
+  T.consumeClose();
+
+  return Actions.OpenMP().ActOnOpenMPLoopRangeClause(
+      FirstVal.get(), CountVal.get(), ClauseNameLoc, T.getOpenLocation(),
+      FirstLoc, CountLoc, T.getCloseLocation());
+}
+
 OMPClause *Parser::ParseOpenMPPermutationClause() {
   SourceLocation ClauseNameLoc, OpenLoc, CloseLoc;
   SmallVector<Expr *> ArgExprs;
@@ -3473,6 +3506,9 @@ OMPClause *Parser::ParseOpenMPClause(OpenMPDirectiveKind DKind,
     }
     Clause = ParseOpenMPClause(CKind, WrongDirective);
     break;
+  case OMPC_looprange:
+    Clause = ParseOpenMPLoopRangeClause();
+    break;
   default:
     break;
   }