In the default case, there's a special case with a few conditions.
Prefer the cheapest conditions first, so we can take advantage of
short-circuiting.
Effect is a small but still significant reduce in shader compilation
times, as can be seen by:
- Fossil replay for Rise of the Tomb Raider
```
Difference at 95.0% confidence
-0.433333 +/- 0.028609
-1.42556% +/- 0.0941163%
(Student's t, pooled s = 0.0337886)
```
- Fossil replay for Batman Arkham City
```
Difference at 95.0% confidence
-8.84 +/- 0.146083
-1.65932% +/- 0.0274207%
(Student's t, pooled s = 0.125423)
```
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Emma Anholt <emma@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25549>
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