Pekka Enberg wrote: > Tomasz Grabiec wrote: > >>>> Tomek Grabiec wrote: > >>>>> The function was setting elem to the init_stack_trace_elem_current()'s > >>>>> frame which is error prone because after function returns its stack > >>>>> frame might be overriden by another function calls done from the > >>>>> caller. > >>>>> > >>>>> A fix for that is to make init_stack_trace_elem_current() set elem to > >>>>> the caller's frame. We must make it a macro becasue we can't rely on > >>>>> __builtin_frame_address(1) because of gcc optimizations. > >>>> We still have few instances of __builtin_frame_address() in the code. I > >>>> guess we need to fix those up as well? > >>> We must only be carefull about __builtin_frame_address(x) when x > 0. > >>> It is safe to call __builtin_frame_address(0). It is also safe to > >>> call __builtin_frame_address(x) for x>0 when it's used inside a function > >>> which is directly called from JIT and from JIT only. > >> Yeah, I meant that we have few instances of __builtin_frame_address(1) > >> that probably need fixing. > > > > I went through __builtin_frame_address() uses, and the only one that > > seems invalid to me is the one in trace_magic_trampoline() in > > jit/trace-jit.c. Is there another use you're worried about? > > Oh, I didn't look too carefully but the one in throw_from_signal_bh() > looks suspicious. Is it really safe to use __builtin_frame_address(2)? >
It is safe, provided that it is called the way that is shown in the comment, which is: jit_method -> signal_bh_trampoline -> signal_bottom_half_handler -> throw_from_signal_bh macro It is safe because signal_bh_trampoline and signal_bottom_half_handler calls are not subject to call optimization. That's because we perform those calls by getting function address with & operator and then perform the call using that address (in assembly). Gcc have no way to figure out if call optimization is possible when it returns function address for & operator, so it must return a pointer to non-call-optimized version). Tomek ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Jatovm-devel mailing list Jatovm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/jatovm-devel
