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e696f5c180
coverage: Dismantle `map_data.rs` by moving its responsibilities elsewhere This is a series of incremental changes that combine to let us get rid of `coverageinfo/map_data.rs`, by moving all of its responsibilities into more appropriate places. Some of the notable consequences are: - We once again build the per-CGU file table on the fly while preparing individual covfun records, instead of building the whole table up-front. The up-front approach was introduced by #117042 to work around various other problems in generating the covmap/covfun records, but subsequent cleanups have made that approach no longer necessary. - Expression conversion and mapping-region conversion are now performed directly in `mapgen::covfun`, which should make future changes easier. - We no longer insert unused function instances into the same map that is also used to track used function instances. This helps to decouple the handling of used vs unused functions. --- There should be no meaningful change to compiler output. The file table is no longer sorted, because reordering it would invalidate the file indices stored in individual covfun records, but the table order should still be deterministic (albeit arbitrary). There are some subsequent cleanups that I intend to investigate, but this is enough change for one PR.
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 bothcoverage-mapandcoverage-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.