On 04/21/2015 06:39 AM, Peter Bergner wrote:
On Tue, 2015-04-21 at 08:22 +0200, Jakub Jelinek wrote:
-#if defined(__powerpc__) || defined(__powerpc64__)
- // PCs are always 4 byte aligned.
- return pc - 4;
-#elif defined(__sparc__) || defined(__mips__)
- return pc - 8;
The SPARC/MIPS case is of course needed, because on these architectures
the call is followed by a delay slot. But I wonder why you need anything
special on any other architecture, why pc - 1 isn't good enough for those.
The point isn't to find a PC of the call instruction, on some targets that
is very hard and you need to disassemble, but to just find some byte in the
call instruction.
I wrote the "pc - 4" code for powerpc* and I guess I was just
being pedantic on returning the first address of the instruction.
If using "pc - 1" works, then I'm fine with that.
It works fine with the patch and produces sensible output
because the decremented address is only used to look up
the debug info and restored before it's output. Otherwise
(with the unpatched code) we'd end up with odd PC addresses
in the stack trace.
Martin
Peter
