[OPENMP] Codegen for 'atomic update' construct.

Adds atomic update codegen for the following forms of expressions:

x binop= expr;
x++;
++x;
x--;
--x;
x = x binop expr;
x = expr binop x;
If x and expr are integer and binop is associative or x is a LHS in a RHS of the assignment expression, and atomics are allowed for type of x on the target platform atomicrmw instruction is emitted.
Otherwise compare-and-swap sequence is emitted:

bb:
...
atomic load <x>
cont:
<expected> = phi [ <x>, label %bb ], [ <new_failed>, %cont ]
<desired> = <expected> binop <expr>
<res> = cmpxchg atomic &<x>, desired, expected
<new_failed> = <res>.field1;
br <res>field2, label %exit, label %cont
exit:
...

Differential Revision: http://reviews.llvm.org/D8536

llvm-svn: 233513
diff --git a/clang/lib/AST/Stmt.cpp b/clang/lib/AST/Stmt.cpp
index 8c76009..4262dc3 100644
--- a/clang/lib/AST/Stmt.cpp
+++ b/clang/lib/AST/Stmt.cpp
@@ -2010,21 +2010,21 @@
 OMPAtomicDirective *
 OMPAtomicDirective::Create(const ASTContext &C, SourceLocation StartLoc,
                            SourceLocation EndLoc, ArrayRef<OMPClause *> Clauses,
-                           Stmt *AssociatedStmt, BinaryOperatorKind OpKind,
-                           Expr *X, Expr *XRVal, Expr *V, Expr *E) {
+                           Stmt *AssociatedStmt, Expr *X, Expr *V, Expr *E,
+                           Expr *UE, bool IsXLHSInRHSPart) {
   unsigned Size = llvm::RoundUpToAlignment(sizeof(OMPAtomicDirective),
                                            llvm::alignOf<OMPClause *>());
   void *Mem = C.Allocate(Size + sizeof(OMPClause *) * Clauses.size() +
                          5 * sizeof(Stmt *));
   OMPAtomicDirective *Dir =
       new (Mem) OMPAtomicDirective(StartLoc, EndLoc, Clauses.size());
-  Dir->setOpKind(OpKind);
   Dir->setClauses(Clauses);
   Dir->setAssociatedStmt(AssociatedStmt);
   Dir->setX(X);
-  Dir->setXRVal(X);
   Dir->setV(V);
   Dir->setExpr(E);
+  Dir->setUpdateExpr(UE);
+  Dir->IsXLHSInRHSPart = IsXLHSInRHSPart;
   return Dir;
 }