Re: RFC: implement typed DWARF stack

[Tom Tromey <tromey@redhat.com>]

>>>>> "Tom" == Tom Tromey <tromey@redhat.com> writes:

Tom> I would appreciate comments on this.  In the absence of comments I am
Tom> going to check it in.

Tom> Jakub recently implemented Cary Coutant's typed DWARF stack proposal in
Tom> GCC.

I had a couple notes I wanted to make that I forgot about when I was
actually writing the email.

First, look at the dwarf2_get_die_type addition in dwarf2read.c.
I am not extremely pleased with this code.  I think due to DIE cache
flushing it may create new types from time to time.

I am not sure what to do about this.  One idea I had was that perhaps
read_type_die_1 could intern base types (meaning we would have to
re-read the DIEs but we would not instantiate new types all the time).
Another idea was to permanently cache base types by DIE -- but this
seemed like too much overhead for a reasonably obscure feature.


The other issue is that you might be wondering why I didn't update the
DWARF->AX compiler in dwarf2loc.c.  The reason is simply that this
extension is, IIUC, mostly useful for floating point and decimal
floating point, and AX cannot express those.

Maybe this can also be used for wider-than-address-sized integral types.
I will look; maybe the AX compiler does need an update for this.

Tom