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Logging ​

warpo’s logging is intentionally lightweight and split into two layers:

  • Always-on user-facing output: diagnostics, errors, and high-level progress printed by the driver / tools.
  • Opt-in debug logs: verbose internal traces intended for pass development and investigations.

This page focuses on the opt-in layer, especially how to filter pass logs using environment variables.

Debug logging via environment variables ​

Debug logging is controlled by these environment variables:

  • WARPO_DEBUG=1

    • Enables all debug logs unconditionally.
    • If this is set, the pass/function filters below are ignored.

  • WARPO_DEBUG_PASSES=...

    • Enables debug logs only for specific passes.
    • Value is a semicolon-separated list of exact pass names.
    • Matching is case-sensitive.

  • WARPO_DEBUG_FUNCTIONS=...

    • Enables debug logs only for specific functions (for code paths that provide a function name).
    • Value is a semicolon-separated list of exact function names.
    • Matching is case-sensitive.

Important behavior:

  • The environment is read once (on first use) and cached for the process lifetime.

Filtering pass logs ​

Most pass-level debug prints are guarded by warpo::support::isDebug(PASS_NAME) (or the function-aware overload). That means you can reduce noise by enabling logs only for the pass(es) you care about.

Enable logs for a single pass ​

bash
export 'WARPO_DEBUG_PASSES=AdvancedInlining'

Enable logs for multiple passes ​

bash
export 'WARPO_DEBUG_PASSES=AdvancedInlining;ImmutableLoadEliminating'

Combine pass + function filtering ​

If you set both WARPO_DEBUG_PASSES and WARPO_DEBUG_FUNCTIONS, a log site guarded by isDebug(passName, functionName) will only emit when both match.

bash
export 'WARPO_DEBUG_PASSES=AdvancedInlining'
export 'WARPO_DEBUG_FUNCTIONS=foo;bar'

Notes:

  • If a particular log site uses only isDebug(PASS_NAME) (no function name), then WARPO_DEBUG_FUNCTIONS has no effect.
  • If you set only WARPO_DEBUG_FUNCTIONS, then function-aware log sites can emit regardless of pass name.

How to find the pass names ​

WARPO_DEBUG_PASSES matches the pass name string used in code.