Explain expected sections-diff differences - #44
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sections-diff now reads sections-divergences.toml, the same way config-diff and flags-diff read their files. A difference counts as explained when a rule covers every section name or site on both sides of it, and the build is clean when nothing is left unexplained and no object exists only in the other build.
The general rules cover sections each optimizer makes for itself (
.rodata.cst*,.rodata,.rodata.str*,.text.unlikely) and bug table sites only rucc has, which are checks gcc proved dead. Every bug table site only gcc has gets its own rule for one object, with the check named and the reason rucc could prove it false. I read each one against the source and its callers. One example is the cpupri.c WARN, where convert_prio has no default case, so every value it defines is below CPUPRI_NR_PRIORITIES.The report lists unexplained differences first, then the explained ones with their reasons.
On 7.2.8 defconfig built from scratch with rucc at ad3de85a1, 3112 objects compared, 200 differences, 200 explained, 0 not, and the command exits 0. config-diff, flags-diff, symvers-diff and vec-audit are also clean on the same pair.
Part of #3.