llvm-project

70742589 - [llvm-dwarfdump][LineCov 2/3] Add coverage baseline comparison and line table coverage in isolation (#183790)

[llvm-dwarfdump][LineCov 2/3] Add coverage baseline comparison and line table coverage in isolation (#183790) Patch 2 of 3 to add to llvm-dwarfdump the ability to measure DWARF coverage of local variables in terms of source lines, as discussed in [this RFC](https://discourse.llvm.org/t/rfc-debug-info-coverage-tool-v2/83266). This patch adds the ability to compare a variable’s coverage against a baseline, e.g. an unoptimised compilation of the same code. This is provided using the optional `--coverage-baseline` argument. When a baseline is provided, the output also includes a per-variable measure of the line table’s coverage (`LT`, `LTRatio`), distinct from the variable’s coverage proper. See section 2.2 of the RFC for details on this metric.