Continuing d6072d37 (Add __builtin_frame_address(0)) implement
__builtin_frame_address for levels greater than zero, in order for
tinycc to be able to compile its own lib/bcheck.c after
cffb7af9 (lib/bcheck: Prevent __bound_local_new / __bound_local_delete
from being miscompiled).
I'm new to the internals, and used the most simple way to do it.
Generated code is not very good for levels >= 2, compare
gcc tcc
level=0 mov %ebp,%eax lea 0x0(%ebp),%eax
level=1 mov 0x0(%ebp),%eax mov 0x0(%ebp),%eax
level=2 mov 0x0(%ebp),%eax mov 0x0(%ebp),%eax
mov (%eax),%eax mov %eax,-0x10(%ebp)
mov -0x10(%ebp),%eax
mov (%eax),%eax
level=3 mov 0x0(%ebp),%eax mov 0x0(%ebp),%eax
mov (%eax),%eax mov (%eax),%ecx
mov (%eax),%eax mov (%ecx),%eax
But this is still an improvement and for bcheck we need level=1 for
which the code is good.
For the tests I had to force gcc use -O0 to not inline the functions.
And -fno-omit-frame-pointer just in case.
If someone knows how to improve the generated code - help is
appreciated.
Thanks,
Kirill
Cc: Michael Matz <matz@suse.de>
Cc: Shinichiro Hamaji <shinichiro.hamaji@gmail.com>
b2a02961b4