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Detect dead code #22
Description
The basic idea is to write a clang plugin which is able to detect if a function in an uncovered file is called (directly or via a call to another function) by an other function in a covered file.
That would avoid manual inspection and give the files with a high probability to be dead.
Activity
[-]shipit_code_coverage: detect dead code[/-][+]Detect dead code[/+]marco-c commentedon Dec 19, 2018
@choller mentioned a similar idea recently.
choller commentedon Dec 19, 2018
It might be that we don't even need a Clang plugin for this because we already have extensive data being generated for searchfox. In fact, I am working on a prototype based on this already and will probably also have this as a Q1 goal to evaluate. I can provide you with the first results once I have them. The first target I am looking at is
intl/because I suspect major amounts of dead code there. Unfortunately it is also one of the uglier targets because it uses weird macro magic to rename several entrypoints on the fly.marco-c commentedon Jan 21, 2019
@choller implemented the solution in https://github.com/MozillaSecurity/reachable.
We could extract the analysis code in a library (that we will share between our project and the
reachableproject), and use it to add another column to our zero coverage report: 'Is Reachable'.marco-c commentedon Jan 21, 2019
I've created a temporary lib at https://github.com/marco-c/reachablelib, which we could move to either mozilla or MozillaSecurity org at some point.
Rename ccov build from opt to debug. Fixes mozilla#22
marco-c commentedon Oct 25, 2019
Wrongly closed, as 5a9c01b was imported from another repo.