As the newly added documentation describes, this reroll serves two purposes:
* to allow shader parameters to be used for any target type (which allows using
parameters for things like Direct3D 8-9 alpha test),
* to allow the union in struct vkd3d_shader_parameter to contain types larger
than 32 bits (by specifying them indirectly through a pointer).
An incoming can be undefined if the PHI result is not used if the
incoming's path was taken, or if the undefined value is consumed by
an instruction (dxc will compile such code without errors).
It is meant as generic pass to host all program changes to single
instructions that do not require keeping a global state, intstead
of having to loop through the whole program many times.
This is in preparation of handling more than one function (as
it happens for Hull Shaders), which will require having a single
row of declarations, but handling more than one CFG.
RADV converts temps to phi instructions, so converting phis to MOVC in
VSIR just translates back to phis feeding into a MOVC. This commit
eliminates the MOVC.
vsir_program_normalise() has function calls to basically everything in
ir.c, so it's useful to have it in an easily reachable place to
quickly jump to wherever you need using your favorite code editor's
features.
The label itself is certainly an unsigned integer, but the register
has no meaningful data type. It cannot be evaluated to anything.
The goal of this is to reduce cluttering in the internal ASM dumps.
The new structurizer therefore reaches feature parity with the
older simple one, except for a couple of points:
* the old structurizer accepts any CFG, without requiring reducibility;
however, the DXIL specification requires the CFG to be reducible
anyway, so we're not really losing anything;
* the new structurizer additionally requires that no block has two
incoming back arrows; AFAIK this is condition that can happen,
but in practice it seems to be rare; also, it's not hard to add
support for it, as soon as it is decided it is useful.
On the other hand, the new structurizer makes use of the merging
information that are reconstructed from the CFG, which is important
for downstream optimization and fundamental for correctly emitting
tangled instructions.
Taking these considerations into account, the old structurizer is
considered superseded and is therefore removed.
