Add the AST node kinds: the Stmt representing the #pragma, the clauses and Transform. The latter represents the semantic analysis result similar to an ImplicitCast. Moreover, the AnalysisTransform component constructs a loop nest tree to which transformations are applied to such that Sema can warn about inconsistencies, e.g. there is no inner or ambiguous loops for unrollandjam.
For a full description, see D69088.