We're explicitly replacing zero with one in the only place where the
plane count being zero or one makes a difference. It also make sense:
UNKNOWN is used for buffers, which for all intents and purposes have one
plane.
Uncovered by the ininf() test in the next commit. This is why we insist
on test coverage; unfortunately this one slipped through in
fd1beedc07becc7e5e49b64273f7bde7f9a8b2a0.
Vertex shaders do not have CMP, so we use SLT and MAD.
For example, this vertex shader:
uniform float4 f;
void main(inout float4 pos : position, out float4 t1 : TEXCOORD1)
{
t1 = (int4)f;
}
results in:
vs_2_0
dcl_position v0
slt r0, c0, -c0
frc r1, c0
add r2, -r1, c0
slt r1, -r1, r1
mad oT1, r0, r1, r2
mov oPos, v0
while we have the lower_cmp() pass, each time it is applied many
instructions are generated, so this patch introduces a specialized
version of the cast-to-int lowering for efficiency.
Turns out we are not doing this correctly in SM1, because the rounding
should be to the number that is closer to zero and lower_casts_to_int()
doesn't do that.
A vertex shader test is added since in SM1 they must rely on the SLT
operation instead of the CMP operation.
fxc compiles this method even without the backcompat option.
Furthermore, it even does it on ps_2_0 despite the fact that it maps to
a texldd instruction, which is not available on plain ps_2_0, nor ps_2_b,
only on ps_2_a and ps_3_0 according to documentation.
It is worth mentioning that the additional offset parameter is not
supported when lowering.
