Tracing
rust-gpu has a lot of debug!
(or trace!) calls, which print out logging information at many points. These are very
useful to at least narrow down the location of a bug if not to find it entirely, or just
to orient yourself as to why the compiler backend is doing a particular thing.
To see the logs, you need to set the RUSTGPU_LOG environment variable to your log filter (note the "GPU" in the name). The full syntax of the log filters can be found in the rustdoc of tracing-subscriber.
Use RUSTGPU_LOG_FORMAT to control log output format ("tree", "flat", or "json") and RUSTGPU_LOG_COLOR to manage color output ("always", "never", or "auto").
To trace non-rust-gpu parts of the compiler, set the standard RUSTC_LOG environment variable.
Replacements for old codegen arguments
Before rust-gpu supported tracing, there were special codegen
arguments to aid observability. As of
PR#196 the they
have been removed and replaced with the following:
--specializer-debug→RUSTGPU_LOG=rustc_codegen_spirv::specializer=debug--print-zombie→RUSTGPU_LOG=print_zombie=debug--print-all-zombie→RUSTGPU_LOG=print_all_zombie=debug