Zalathar 2e6f4a5922 coverage: Re-land "Enlarge empty spans during MIR instrumentation"
This allows us to assume that coverage spans will only be discarded during
codegen in very unusual situations.
2025-07-30 13:17:05 +10:00
..

The tests in this directory are shared by two different test modes, and can be run in multiple different ways:

  • ./x.py test coverage-map (compiles to LLVM IR and checks coverage mappings)
  • ./x.py test coverage-run (runs a test binary and checks its coverage report)
  • ./x.py test coverage (runs both coverage-map and coverage-run)

Maintenance note

These tests can be sensitive to small changes in MIR spans or MIR control flow, especially in HIR-to-MIR lowering or MIR optimizations.

If you haven't touched the coverage code directly, and the tests still pass in coverage-run mode, then it should usually be OK to just re-bless the mappings as necessary with ./x.py test coverage-map --bless, without worrying too much about the exact changes.