> > There are two problems here > > 1) We do not stream builtin decls and merge them outside lto-symtab (by > > just > > streaming references to builtins with their asm names). There is at > > least > > one extra PR related to this and on my TODO is to simply remove the > > code. > > 2) Aliases within single unit works only when both the alias and the > > target use > > asm name. This is because internally we store mangled > > DECL_ASSEMBLER_NAME and the > > alias_pair code. > > With LTO this breaks existing code simply because what used to be > > multiple units > > and thus safe is now single LTO unit. > > > > Dave Korn fixed part of the problem by introducing mangling code into > > lto-symtab > > His code solve similar problems with aliases from the asm code, but it > > did not solve the problem with aliases from LTO units, like here, > > simply > > because alias pair code bypass the lto-symtab. One of goals of the > > incorrect patch > > above is to make lto-symtab to do the merging and thus fix this issue > > (for now at > > all decls except for builtins). > > > > Still it would be good to solve the problem on non-LTO compilation, > > too. > > We discussed introduction of proper symbol table into GCC at the GCC > > gathering last > > weekend. It is where I am heading but it will take some time. > > > > Until that happens, I suggest fixing the testcase same was as we already > > fixed > > the memops-asm-lib.c in 4.6 timeframe. > > > > Bootstrapped/regtested x86_64-linux, OK? > > Ok. Hi, thanks! Could you, please, also consider the second two variants I sent? In general attribute used is needed when implementing libfuncs since we never know when folding will intoduce new libcall (like in memops-asm). However this particular case don't need use because the builtin is called directly. They also solve the problem of BLOCK lists being messed up.
In meantime I tested both variants and they pass. I will add a changelog, of course. Honza
