target/hexagon: introduce new helper functions

target/hexagon: introduce new helper functions

These helpers will be employed by the idef-parser generated code, to
correctly implement instruction semantics. "Helper" functions, in the
context of this patch, refers to functions which provide a manual TCG
implementation of certain features.

Signed-off-by: Alessandro Di Federico <ale@rev.ng>
Signed-off-by: Niccolò Izzo <nizzo@rev.ng>
Signed-off-by: Anton Johansson <anjo@rev.ng>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Taylor Simpson <tsimpson@quicinc.com>
Message-Id: <20220923173831.227551-6-anjo@rev.ng>