[OPENMP 4.0] Initial support for 'omp declare reduction' construct.

Add parsing, sema analysis and serialization/deserialization for 'declare reduction' construct.
User-defined reductions are defined as

#pragma omp declare reduction( reduction-identifier : typename-list : combiner ) [initializer ( initializer-expr )]
These custom reductions may be used in 'reduction' clauses of OpenMP constructs. The combiner specifies how partial results can be combined into a single value. The
combiner can use the special variable identifiers omp_in and omp_out that are of the type of the variables being reduced with this reduction-identifier. Each of them will
denote one of the values to be combined before executing the combiner. It is assumed that the special omp_out identifier will refer to the storage that holds the resulting
combined value after executing the combiner.
As the initializer-expr value of a user-defined reduction is not known a priori the initializer-clause can be used to specify one. Then the contents of the initializer-clause
will be used as the initializer for private copies of reduction list items where the omp_priv identifier will refer to the storage to be initialized. The special identifier
omp_orig can also appear in the initializer-clause and it will refer to the storage of the original variable to be reduced.
Differential Revision: http://reviews.llvm.org/D11182

llvm-svn: 262582

1 files changed, 13 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 0ca5555e1da..b644ff215cd 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -376,6 +376,19 @@ bool Sema::DiagnoseUseOfDecl(NamedDecl *D, SourceLocation Loc,
         DeduceReturnType(FD, Loc))
       return true;
   }
+
+  // [OpenMP 4.0], 2.15 declare reduction Directive, Restrictions
+  // Only the variables omp_in and omp_out are allowed in the combiner.
+  // Only the variables omp_priv and omp_orig are allowed in the
+  // initializer-clause.
+  auto *DRD = dyn_cast<OMPDeclareReductionDecl>(CurContext);
+  if (LangOpts.OpenMP && DRD && !CurContext->containsDecl(D) &&
+      isa<VarDecl>(D)) {
+    Diag(Loc, diag::err_omp_wrong_var_in_declare_reduction)
+        << getCurFunction()->HasOMPDeclareReductionCombiner;
+    Diag(D->getLocation(), diag::note_entity_declared_at) << D;
+    return true;
+  }
   DiagnoseAvailabilityOfDecl(*this, D, Loc, UnknownObjCClass,
                              ObjCPropertyAccess);