On 2/22/19 4:29 AM, Richard Biener wrote: > > GCC builds are currently not reproducible because for one the checksum > we compute for PCH purposes (by genchecksum) nowaways includes checksums > of archives (since we switched from checksumming a dummy executable > to checksumming object files). That includes dates (unless built with > -D which we don't do). > > Then later we switched to do thin archives so for example libbackend.a > we checksum doesn't contain the actual code anymore... > > A pragmatic approach to "fix" things would be to just checksum > gtype-desc.o which should have enough state to cover PCH dependences > if I understand the workings correctly (patch below - a single > checksum would suffice so more simplifications are possible). > > Another solution working on ELF systems with build-id support is > simply forgo checksumming anything and rely on the executable > build-id instead (pat^whack below as well). > > Does anybody think that just checksumming gtype-desc.o is a > degradation over the current state (which checksums thin archives)? > > Thanks, > Richard. > > 2019-02-22 Richard Biener <rguent...@suse.de> > > c/ > * Make-lang.in (cc1-checksum.c): Checksum only gtype-desc.o. > > cp/ > * Make-lang.in (cc1plus-checksum.c): Checksum only gtype-desc.o. > > objc/ > * Make-lang.in (cc1obj-checksum.c): Checksum only gtype-desc.o. > > objcp/ > * Make-lang.in (cc1objplus-checksum.c): Checksum only gtype-desc.o. ISTM that gtype-desc effectively describes the structure of all the GC data.
Given we're summing the thin-archives, we're already missing things like a change in static data. So I don't think your patch is a degradation over the current state. I'm not 100% sure the current state is correct though :-) jeff
