Pipeline states are created on compile threads, along with the shader
functions they need, which compile once on first use. Draws record a
handle to the pipeline state, and the render thread waits for it if it
gets there first, as with Vulkan, so the emu thread never waits for a
compile. Translation to MSL stays synchronous, as recording needs the
texture masks it produces.
Each game's shader IDs and pipeline keys are saved to a
<discID>.mtlshadercache, and recreated while the game boots. macOS's own
Metal cache then makes them quick: Wipeout Pure's 36 pipelines took
25 ms, or 260 ms with an empty Metal cache, instead of stalls during
play.
Cold Wipeout Pure, 5 emulated seconds from a savestate: 3.0 s before,
1.6 s with the background compiles alone.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
