Hi!
On Thu, Aug 26, 2021 at 11:53:24AM -0300, Raphael Moreira Zinsly wrote:
> Without dwarf2 unwind tables available _Unwind_Backtrace() is not
> able to return the full backtrace.
> This patch adds a fallback function on powerpc to get the backtrace
> by doing a backchain, this code was originally at glibc.
Okay, the backchain as fallback if other (better!) methods cannot work.
> * config/rs6000/linux-unwind.h (struct rt_sigframe): Move it to
> outside of get_regs() in order to use it in another function,
> this is done twice: for __powerpc64__ and for !__powerpc64__.
> (struct trace_arg): New struct.
> (struct layout): New struct.
> (ppc_backchain_fallback): New function.
> * unwind.inc (_Unwind_Backtrace): Look for _URC_NORMAL_STOP
> code state and call MD_BACKCHAIN_FALLBACK.
Changelog lines wrap at 80 chars, not 70 or so. The emails from commits
(to bugzilla) are a bit malformed (it counts the number of columns for
leading tabs wrong it seems), but the actual commits are just fine.
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/unwind-backchain.c
> @@ -0,0 +1,22 @@
> +/* { dg-do run { target { powerpc*-*-linux* } } } */
Don't say such targets in gcc.target/powerpc/ tests please. Everything
in gcc.target is for powerpc*-*-* already, so if you really want to
limit to powerpc*-*-linux* just write *-*-linux*. But there are better
ways to get what you want, like, testing for the actual feature you want
(which is if backtrace() works?) But such an improvement can be done
later (and needs more testing etc).
But please write some simple comment saying why you need -linux* in the
test.
> +void
> +test_backtrace()
> +{
> + int addresses;
> + void *buffer[10];
> +
> + addresses = backtrace(buffer, 10);
> + if(addresses != 4)
> + __builtin_abort();
> +}
Does that work?! Has this been tested on all powerpc*-linux configs?
Importantly also BE and 32-bit.
Okay for trunk with the testcase fix, if all testing works out. Thanks!
Segher
