Since all SSA values are immutable, no value copying is required for
any operations except those that load from or store to a variable;
those operations must do an aggregate copy, i.e., descend into struct
and array elements. All other calls to copyVal have been removed;
they were pieces of duct tape, as I had long suspected.
The descent must be based on the static type information, not the
"shape" of the dynamic value, since two reflect.Value structs may have
different internal shapes. We clobber the true definition of
reflect.Value's underlying type, replacing it with struct{interface{},
interface{}}, which is close enough to make the load/store functions
work.
+ Test
Change-Id: I5e239d91ed0cb2a669a9f75766024fe1f9a5c347
Reviewed-on: https://go-review.googlesource.com/7532
Reviewed-by: Robert Griesemer <gri@golang.org>
868c429971