mirror of
https://gitlab.winehq.org/wine/vkd3d.git
synced 2024-11-21 16:46:41 -08:00
51f13391e6
The structurizer is implemented along the lines of what is usually called the "structured program theorem": the control flow is completely virtualized by mean of an additional TEMP register which stores the block index which is currently running. The whole program is then converted to a huge switch construction enclosed in a loop, executing at each iteration the appropriate block and updating the register depending on block jump instruction. The algorithm's generality is also its major weakness: it accepts any input program, even if its CFG is not reducible, but the output program lacks any useful convergence information. It satisfies the letter of the SPIR-V requirements, but it is expected that it will be very inefficient to run on a GPU (unless a downstream compiler is able to devirtualize the control flow and do a proper convergence analysis pass). The algorithm is however very simple, and good enough to at least pass tests, enabling further development. A better alternative is expected to be upstreamed incrementally. Side note: the structured program theorem is often called the Böhm-Jacopini theorem; Böhm and Jacopini did indeed prove a variation of it, but their algorithm is different from what is commontly attributed to them and implemented here, so I opted for not using their name.
47 lines
749 B
Plaintext
47 lines
749 B
Plaintext
% The ternary operator works differently in sm6.
|
|
% It now shortcuts, and is no longer per-component.
|
|
|
|
[require]
|
|
shader model >= 6.0
|
|
|
|
[pixel shader]
|
|
uniform float4 x;
|
|
|
|
float4 main() : sv_target
|
|
{
|
|
return x.x ? x : x - 1;
|
|
}
|
|
|
|
[test]
|
|
uniform 0 float4 2.0 3.0 4.0 5.0
|
|
draw quad
|
|
probe all rgba (2.0, 3.0, 4.0, 5.0)
|
|
uniform 0 float4 0.0 10.0 11.0 12.0
|
|
draw quad
|
|
probe all rgba (-1.0, 9.0, 10.0, 11.0)
|
|
|
|
|
|
[pixel shader]
|
|
float4 f;
|
|
|
|
float4 main() : sv_target
|
|
{
|
|
float f1 = 0.1, f2 = 0.2, f3;
|
|
f3 = f.x ? (f1 = 0.5) + 0.2 : (f2 = 0.6);
|
|
return float4(f1, f2, f3, 0.0);
|
|
}
|
|
|
|
[test]
|
|
uniform 0 float4 1.0 0.0 0.0 0.0
|
|
draw quad
|
|
probe all rgba (0.5, 0.2, 0.7, 0.0)
|
|
|
|
|
|
[pixel shader fail]
|
|
float4 x, y, z;
|
|
|
|
float4 main() : sv_target
|
|
{
|
|
return x ? y : z;
|
|
}
|