[TSAR, Parallel, Parallel] Add ParallelItem class to represent the result of parallelization.

We also add classes to represent some of the DVMH directives.
We split the parallelization process into two steps.
In the first step, parallel directives will be attached to basic blocks.
This allows us to implement the optimization of a parallel program in further commits.
In the second step, DVMH directives should be inserted into the source code.

Author: kaniandr

include/tsar/Support/Directives.td

@@ -100,9 +100,13 @@ def Assert     : Directive<"assert">;
 def Region     : Directive<"region">;
 def Metadata   : Directive<"metadata">;
 
-def DvmTemplate: Directive<"template", Dvm>;
-def DvmArray   : Directive<"array", Dvm>;
-def DvmInherit : Directive<"inherit", Dvm>;
+def DvmTemplate  : Directive<"template", Dvm>;
+def DvmArray     : Directive<"array", Dvm>;
+def DvmInherit   : Directive<"inherit", Dvm>;
+def DvmRegion    : Directive<"region", Dvm>;
+def DvmParallel  : Directive<"parallel", Dvm>;
+def DvmActual    : Directive<"actual", Dvm>;
+def DvmGetActual : Directive<"get_actual", Dvm>;
 
 // Define one clause.
 class Clause<string name, Directive parent, list<Expr> expr_list = []> {