When a type is aliased, the alias has two type chains: the simple type
chain with all other aliases stripped, and the full type chain. There
are still plenty of bugs in it, but having the clean type chain takes
care of the major issue that was in the previous attempt as only the
head of the type-chain needs to be skipped for type comparison.
Most of the bugs are in finding the locations where the head needs to be
skipped.
It proved to be too fragile in its current implementation. It broke
pointers to incomplete structs and switch enum checking, and getting it
to work for other things was overly invasive. I still want the encoding,
but need to come up with something more robust.a
I was originally going to put it in the debug syms file, but I realized
that the data persistence code would need access to both def type and
certainly correct def offsets for defs in far data.
This far better reflects the actual meaning. It is very likely that
ty_none is a holdover from long before there was full type encoding and
it meant that the union in qfcc's type_t had no data. This is still
true for basic types, but only if not a function, field or pointer type.
If the type was function, field or pointer, it was not true, so it was
misnamed pretty much from the start.
The encoding is 3:5 giving 3 bits for alignment (log2) and 5 bits for
size, with alignment in the 3 most significant bits. This keeps the
format backwards compatible as until doubles were added, all types were
aligned to 1 word which gets encoded as 0, and the size is unaffected.
I plan on adding doubles, and so it's necessary to ensure that attempts
to align doubles in local or far data spaces remain aligned after final
linking.
After messing with SIMD stuff for a little, I think I now understand why
the industry went with xyzw instead of the mathematical wxyz. Anyway, this
will make for less pain in the future (assuming I got everything).
It is necessary to know if a def is a function parameter so it can be
treated as initialized by the flow analyzer. The support for the flag in
object files is, at this stage, purely for debugging purposes.
First, the class def needed to be created before the class type, then the
def space indices had to be set early, otherwise the relocs wound up with
space 0 instead of the correct space.
The base of the type encodings block is given by the .type_encodings def.
The block begins with a "null" type (4 words of 0), followed by the first
type encoding.
At some stage, I will need to add information for extended def information
(32 bit offset, type encoding, other?), but this is good for initial
testing.
The debug info expects local defs to be 0 based, so once relocations in
the progs data have been completed, undo the local def offset relocation
so that the correct offsets will be written to the debug info.
