50 lines
2.3 KiB
Markdown
50 lines
2.3 KiB
Markdown
# Debugging Dawn
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## Toggles
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There are various debug-related Toggles that can help diagnose issues. Useful debug toggles:
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- `dump_shaders`: Log input WGSL shaders and translated backend shaders (MSL/ HLSL/DXBC/DXIL / SPIR-V).
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- `disable_symbol_renaming`: As much as possible, disable renaming of symbols (variables, function names, etc.). This can make dumped shaders more readable.
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- `emit_hlsl_debug_symbols`: Sets the D3DCOMPILE_SKIP_OPTIMIZATION and D3DCOMPILE_DEBUG compilation flags when compiling HLSL code.
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- `use_user_defined_labels_in_backend`: Forward object labels to the backend so that they can be seen in native debugging tools like RenderDoc, PIX, or Mac Instruments.
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Toggles may be enabled/disabled in different ways.
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- **In code:**
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Use extension struct `DawnTogglesDescriptor` chained on `DeviceDescriptor`.
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For example:
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```c++
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const char* const enabledToggles[] = {"dump_shaders", "disable_symbol_renaming"};
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wgpu::DawnTogglesDescriptor deviceTogglesDesc;
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deviceTogglesDesc.enabledToggles = enabledToggles;
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deviceTogglesDesc.enabledTogglesCount = 2;
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wgpu::DeviceDescriptor deviceDescriptor;
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deviceDescriptor.nextInChain = &deviceTogglesDesc;
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```
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- **Command-line for Chrome**
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Run Chrome with command line flags`--enable-dawn-features` and/or `--disable-dawn-features` to force enable/disable toggles. Toggles should be comma-delimited.
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For example:
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`--enable-dawn-features=dump_shaders,disable_symbol_renaming`
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- **Command-line for dawn_end2end_tests/dawn_unittests**
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Run Dawn test binaries with command line flags`--enable-toggles` and/or `--disable-toggles` to force enable/disable toggles. Toggles should be comma-delimited.
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For example:
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`dawn_end2end_tests --enable-toggles=dump_shaders,disable_symbol_renaming`
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## Environment Variables
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- `DAWN_DEBUG_BREAK_ON_ERROR`
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Errors in WebGPU are reported asynchronously which may make debugging difficult because at the time an error is reported, you can't easily create a breakpoint to inspect the callstack in your application.
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Setting `DAWN_DEBUG_BREAK_ON_ERROR` to a non-empty, non-zero value will execute a debug breakpoint
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instruction ([`dawn::Breakpoint()`](https://source.chromium.org/chromium/chromium/src/+/main:third_party/dawn/src/dawn/common/Assert.cpp?q=dawn::Breakpoint)) as soon as any type of error is generated.
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