I just pushed what I have right now. It's on branch gcc-ddc on my github. Should I post a patch here?
2017-11-21 0:16 GMT+01:00 Gábor Boskovits <boskov...@gmail.com>: > The only problematic one seems to be standard_libexec_prefix, because that > is used in line 3654 of gcc/gcc.c in a real assignment. > It is also used in line 64 of gcc/gcc-ar.c. > > Other uses of all these other symbols could be calculated as compile time > realitve paths, and if we can live with these paths staying in the same > store directory, then it would be ok. > > This problematic use pattern is in the from: > > x=make_relative_prefix(y,standard_exec_prefix,standard_libexec_prefix); > if(!x) x=standard_libexec_prefix; > > Code of make_relative_prefix is in libiberty/make-relative-prefix.c. > > Assuming sane values (not nulls, existing program name, valid > GCC_EXEC_PREFIX) we get null in the following cases: > 1. GCC_EXEC_PREFIX(or the program name directory component)==standard_exec_ > prefix > 2. if the path present in standard_exec_prefix and standard_libexec_prefix > has no common directories(starting from the beginning) > 3. in case of allocation failure. > > We can safely assume that case 2 does not happen, as we at least have > /gnu/store there, I think. > Nothing can be done about case 3, I don't think we get too far in that > case anyway... > > So, when this happens we simply have case 1: we are not relocated. > > In gcc/gcc.c this pattern is guarded by if(gcc_exec_prefix) basically.(it > is in an else block) > It is not so in gcc/gcc-ar.c. > > This is how far I could get with it by now. > > 2017-11-20 23:14 GMT+01:00 Ricardo Wurmus <rek...@elephly.net>: > >> >> Jan Nieuwenhuizen <jann...@gnu.org> writes: >> >> > Gábor Boskovits writes: >> > >> > Hey Gábor! >> > >> > [cc: guix-devel] >> > >> >> I'm definietly making progress on this. Now I have a working debug >> build of gcc. >> >> Identified the critical symbols, they are: >> > >> >> static const char *const standard_exec_prefix = STANDARD_EXEC_PREFIX; >> >> static const char *const standard_libexec_prefix = >> STANDARD_LIBEXEC_PREFIX; >> >> static const char *const standard_bindir_prefix = >> STANDARD_BINDIR_PREFIX; >> > >> > Oh nice! >> > >> >> The problem fundamentally is that they are calculated from prefix >> passed to configure. >> >> I've checked, that that is the store location. >> > >> > Right. >> > >> >> How should we go on with this? >> >> >> >> Is it possible to pass other value as prefix, or should we keep prefix >> as is, and patch the makefile? >> >> It is set from line 2092 in gcc/Makefile.in by the way. >> > >> > Good question. I think we should try patching the Makefile.in. >> >> I’m just throwing this in, even though I suspect that it is a terrible >> idea: we could replace these symbols with calls to getenv and provide >> the values at runtime with a separate wrapper that would be excluded in >> the comparison. >> >> -- >> Ricardo >> >> GPG: BCA6 89B6 3655 3801 C3C6 2150 197A 5888 235F ACAC >> https://elephly.net >> >> >> >
