I already had the texture's wrapping set up to use different behavior for
nearest or linear, so we just needed to saturate the coordinates in linear
mode to get the "proper" blend between the edge and border values.
A bit of spec text suggested that (like vc4) condition codes should be
used for discards, and the simulator was fine with it, but the 7268
disagrees and you have to use SETMSF instead or the color comes through.
Fixes glsl-fs-discard-01 and many of the interpolation-with-clipping
tests.
In order to keep early-Z from writing early in a discard shader, you need
to set the "modifies Z" bit in the shader state (which the new
prog_data.discards will indicate). Then, in the shader we do a TLB write
to make Z passthrough happen (the QPU result is ignored, so we use a NULL
source).
This is a pretty straightforward fork of VC4's NIR compiler to VC5. The
condition codes, registers, and I/O have all changed, making the backend
hard to share, though their heritage is still recognizable.
v2: Move to src/broadcom/compiler to match intel's layout, rename more
"vc5" to "v3d", rename QIR to VIR ("V3D IR") to avoid symbol conflicts
with vc4, use new v3d_debug header, add compiler init/free functions,
do texture swizzling in NIR to allow optimization.
