https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64164
--- Comment #20 from Alexandre Oliva <aoliva at gcc dot gnu.org> --- (In reply to Alexandre Oliva from comment #18) > No, we don't even *consider* the coalescing performed in the -DOPT case, > because, as noted in comment 13, the SSA names ended up with different base > names, because copyrename wouldn't give them the same base name. > > (In reply to Richard Biener from comment #17) > > To add to all this - IMHO copyrename should go > > That's fine with me. > > > Yes, out-of-SSA coalescing could be changed to allow coalescing of SSA names > > with a user-DECL and anonymous SSA names (or SSA names with a DECL_IGNORED_P > > decl). But that will make the conflict graph much larger(?). Not only that: unless we allow also coalescing between different SSA names in out-of-ssa, we'll lose optimizations that copyrename would have enabled out-of-SSA to make, because the removed copyrename won't have assigned the same base name to otherwise unrelated SSA names that out-of-SSA won't even consider for coalescing. Now *this* might make the conflict graph explode in size.
