perf: cache resolved zig command in wrapper scripts to skip per-invocation probes - #469
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…ation probes find_zig() ran on every compiler invocation and always spawned `python -m ziglang version` (paying Python interpreter startup just to fail on systems without the pip package) and then `zig version` for validation — ~40ms per zig cc call even though the toolchain was already resolved and validated when the wrapper was generated. Export the resolved command as CARGO_ZIGBUILD_ZIG_COMMAND(_ARGS) in the generated wrapper scripts and trust it in find_zig() when the path still exists, falling back to probing otherwise. Measured on macOS (zig 0.16.0): wrapper overhead vs raw zig cc drops from ~52ms to ~11ms per invocation (85ms -> 44ms total for a -### call). Fixes #244 Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01W1Kk6AucizDRZdBDVGipXF
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Summary
Addresses the per-invocation overhead measured in #244.
find_zig()runs on everycargo-zigbuild zig ccinvocation and always spawned two processes before doing any work:python -m ziglang version— paying full Python interpreter startup (~15ms) just to fail on systems without the pip package,zig version— ~31ms of zig startup for validation, even thoughCARGO_ZIGBUILD_ZIG_VERSIONalready carries the version.The toolchain was already resolved and validated when the wrapper script was generated, so re-probing per compile is pure waste — for C-heavy builds it's paid hundreds of times.
This exports the resolved command as
CARGO_ZIGBUILD_ZIG_COMMAND(+CARGO_ZIGBUILD_ZIG_COMMAND_ARGSfor thepython -m ziglangmode) in the generated sh and bat wrappers, and hasfind_zig()trust it when the path still exists — falling back to the normal probe order if it doesn't (e.g. zig was moved between builds; the next wrapper regeneration re-resolves).Numbers (macOS, zig 0.16.0, hyperfine, real-build env)
-###callzig cc -###The remaining ~11ms is sh + cargo-zigbuild binary startup and arg filtering.
Verified:
cargo test --libpasses; real builds foraarch64-apple-darwinandx86_64-unknown-linux-gnu.2.17regenerate wrappers with the new exports and build cleanly. Clippy warnings are pre-existing.🤖 Generated with Claude Code
https://claude.ai/code/session_01W1Kk6AucizDRZdBDVGipXF