This patch introduces the function GetConstant(), which is used by
expr compute function and UDFs to access query constants. There is a
corresponding GetIrConstant() function that returns the IR versions of
the same constants. Currently the only implemented constants are the
expr's return type and argument types, but other constants can be
easily be added to these functions. Interpreted expr functions run
normally, but cross-compiled functions can be passed to
InlineConstants(), which looks for calls to GetConstant() and replaces
them with the result of calling GetIrConstant().
I used this technique in the decimal functions that previously were
not switching on the type at all. The performance of LeastGreatest()
after this patch is the same as it was before it switched on the type.
Change-Id: I8b55744551830d894318a7bab6b6f045fb8bed41
Reviewed-on: http://gerrit.cloudera.org:8080/352
Reviewed-by: Skye Wanderman-Milne <skye@cloudera.com>
Tested-by: Internal Jenkins
7801aa499f