[Bug sanitizer/55739] asan doesn't work on common symbols

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55739

--- Comment #4 from H.J. Lu <hjl.tools at gmail dot com> 2012-12-19 16:58:34 UTC ---
The symbol size is always available at link-time or run-time.
We just never find a use for it in program itself.  We can add
relocations for "foo@BOUND", which resolve to original
calculation of symbol "foo" + size of "foo".