On Sat, Apr 7, 2012 at 21:45, Andrew Turner <and...@fubar.geek.nz> wrote: > On Sun, 8 Apr 2012 04:36:27 +0000 (UTC) > Andrew Turner <and...@freebsd.org> wrote: > >> Author: andrew >> Date: Sun Apr 8 04:36:27 2012 >> New Revision: 234014 >> URL: http://svn.freebsd.org/changeset/base/234014 >> >> Log: >> Unlike other functions __aeabi_read_tp function must preserve >> r1-r3. The currently generated code clobbers r3. Fix this by loading >> ARM_TP_ADDRESS using inline assembly. >> >> Approved by: imp (mentor) > > This fixes thread local storage on ARM in cases when the compiler loads > the offset of the variable in r3 before calling __aeabi_read_tp as has > been observed when the variable is in a shared library.
I don't believe this is safe unless you specify __attribute__ ((__naked__)) in the declaration — currently the compiler is free to clobber registers that the calling convention/ABI allows it to clobber. I don't see the benefit of implementing this in C over using an assembly file, that said, although GCC does have this attribute precisely to allow one to write assembly in a C source file without having to worry about unexpected behavior. How do you know GCC won't allocate r2 to be used as a temporary in between the assembly and the return? I tried to raise this concern on IRC previously, but hopefully it's clearer now. Thanks, Juli. _______________________________________________ svn-src-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"