Fix pathological complexity explosion for certain shaders. #1594
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Certain shaders where functions have a *ton* of merging control flow will end up with exponential time complexity to figure out parameter preservation semantics. The trivial fix to make it O(1) again is to terminate recursive traversal early if we've seen the path before. Simple oversight :(
This was referenced Jan 19, 2021
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1163: Bump gfx to latest master r=kvark a=mkeeter **Connections** - This bumps `gfx` to [#3610](gfx-rs/gfx#3610), and also includes [#3608](gfx-rs/gfx#3608) and [#3609](gfx-rs/gfx#3608) - [Here](gfx-rs/wgpu-native#66) is a draft PR to `wgpu-native` - `wgpu-rs` requires a one-line fix to the `texture_view_drop` call (which now takes a boolean); I can PR this next. **Description** This fixes [pathological shader complexity in SPIRV-Cross](KhronosGroup/SPIRV-Cross#1594), as well as a few other `gfx` PRs. **Testing** I updated `wgpu-native` to use this branch, then updated my [toy raytracer](https://github.com/mkeeter/rayray) to use the resulting `dylibs` and confirmed that it no longer takes forever to compile the pathological shader. In addition, I updated `wgpu-rs` and went through the examples; nothing seems out of place. Co-authored-by: Matt Keeter <matt.j.keeter@gmail.com>
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Certain shaders where functions have a ton of merging control flow
will end up with exponential time complexity to figure out parameter
preservation semantics.
The trivial fix to make it O(1) again is to terminate recursive traversal early if we've seen
the path before. Simple oversight :(
Fix #1591.