https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65780
--- Comment #14 from H.J. Lu <hjl.tools at gmail dot com> --- (In reply to Jakub Jelinek from comment #10) > (In reply to H.J. Lu from comment #9) > > Created attachment 35327 [details] > > A different patch > > > > On x86, this issue only shows up with PIE. Here is a different > > patch to treat common symbol defined locally only if the backend > > passes true common_maybe_local. For x86-64, it is true only if > > HAVE_LD_PIE_COPYRELOC is 1. For i386, it is always false. If > > we aren't building PIE, common_maybe_local is true or false > > doesn't make a difference for x86 since the common symbol is > > always referenced normally with copy reloc. For PIE on x86-64, > > common symbol is local only if HAVE_LD_PIE_COPYRELOC is 1. > > + > + /* For common symbol, it is defined locally only if common_maybe_local > + is true. */ > + bool defined_locally = (!DECL_EXTERNAL (exp) > + && (!DECL_COMMON (exp) || common_maybe_local)); > > I think better would be: > bool uninited_common = (DECL_COMMON (exp) > && (DECL_INITIAL (exp) == NULL > || (!in_lto_p && DECL_INITIAL (exp) == > error_mark_node))); > /* For common symbol, it is defined locally only if common_maybe_local > is true. */ > bool defined_locally = (!DECL_EXTERNAL (exp) && (!uninited_common || > common_maybe_local)); > ... > and then use > /* Uninitialized COMMON variable may be unified with symbols > resolved from other modules. */ > if (uninited_common && !resolved_locally) > return false; What does initialized COMMON look like to linker? If it is marked as COMMON symbol to linker, it will be treated the same as uninitialized COMMON symbol.
