builtin_return_addr vs frame_pointer_needed vs -O3

[Richard Henderson]

On Wed, Jun 26, 2002 at 05:42:10PM +0930, Ian Dall wrote:
> The problem is, test4a() uses __builtin_return_address(1). Turning of
> FRAME_POINTER_REQUIRED for the current function if it accesses a
> previous frame does not work for __builtin_return_address(n) when n
> greater than 1. To do that, you need to ensure that there are frame
> pointers in all the intervening frames, not just the current frame.

True, but so what?

> It is not practical (or maybe even determinable) to work out all the
> functions which could be in the stack trace, so I think a better
> solution would be for RETURN_ADDR_RTX to do something like:
> 
>  ((COUNT > 0 && flag_omit_frame_pointer) ? NULL_RTX: GEN_RTX (...))

*shrug* Perhaps.  My thought had been that just because this
translation unit uses flag_omit_frame_pointer doesn't mean 
that the calling translation unit did.  But on the other hand
I suppose it's a relatively safe assumption that the entire
application is compiled with the same cflags.


r~