This was originally left alone in order to allow functions without early return
to succeed, since in that case we would already emit the correct bytecode
despite not handling the HLSL_IR_JUMP_RETURN instruction.
Now that we lower return statements, however, any unhandled instructions are
either definitely going to result in invalid bytecode, or rare enough that it's
not worth returning success anyway.
SM1 dp2add doesn't map src swizzles to the dst writemask, also it
expects the last argument to have a replicate swizzle.
Before this patch we were writing the operation as:
```
dp2add r0.x, r1.x, r0.x, r2.x
```
and now it is:
```
dp2add r0.x, r1.xyxx, r0.xyxx, r2.x
```
dp2add now has its own function, write_sm1_dp2add(), since it seems to
be the only instruction with this structure.
Ideally we would be using the default swizzles for the first two src
arguments:
```
dp2add r0.x, r1, r0, r2.x
```
since, according to native's documentation, these are supported for all
sm < 4.
But this change -- along with following the convention of repeating the
last component of the swizzle when fewer than 4 components are to be
specified -- would require more global changes, probably in
hlsl_swizzle_from_writemask() and hlsl_map_swizzle().
Because of the change introduced in
f21693b2 vkd3d-shader/hlsl: Use reg_size as component count when allocating a single register.
SM1 scalars and vectors were not longer getting the correct writemask
when they are allocated.
This happened because they have to reserve the whole register even if
they only use some of its components, so their reg_size may differ from
the number of components.
This commit fixes that.
Prevent them from being ever looked up.
Our naming scheme for synthetic variables already effectively prevents this, but
this is better for clarity. We also will need to be able to move some named
variables into a dummy scope to account for complexities around function
definition and declarations.
In practice they never fail. If they fail, it means that there
is some underlying platform problem and there is little we can do
anyway. Under pthreads function prototypes allow returning failure,
but that's only used for "error checking" mutexes, which we
don't use.
On the other hand, error handling in vkd3d is rather inconsistent:
sometimes the errors are ignored, sometimes logged, sometimes
passed to the caller. It's hard to handle failures appropriately
if you can't even keep your state consistent, so I think it's
better to avoid trying, assume that synchronization primitives do
not fail and at least have consistent logging if something goes
wrong.
Vectors cannot be used as array indexes, however, single-component
swizzles (such as vec.x) can be used.
This suggests that single-component swizzles should actually be
scalars and not vectors of dimx = 1.
It is worth noting that the use of single-component swizzles on scalars
should still be allowed.
