[fpc-devel] x86_64 stabs info - patch (sort of)

[Willibald Krenn]

Hi,

On my Win64 machine, gdb kept crashing whenever I tried to step into 
fpc_raiseexception with an error saying that the reg '-1' wasn't 
defined. And yes, stabs info showed:


4943   FUN    0      187    0000000000408710 66408  fpc_raiseexception:F129
4944   RSYM   0      625    0000000000000001 66432  OBJ:R129
4945   RSYM   0      625    0000000000000002 66441  ANADDR:R4
4946   RSYM   0      625    00000000ffffffff 66451  AFRAME:R4

(AFRAME should be 8, since it's passed in R8...)

So in the end I looked into x86reg.dat and was quite amazed that stabs 
index for all 'new' AMD64 regs is set to -1, which is wrong of course. 
Hacking along I changed the stabs-reg indices to match the dwarf64 index 
(see also here: 
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/amd64-tdep.h?rev=1.18&content-type=text/x-cvsweb-markup&cvsroot=src) 
and after bootstrapping the compiler, I can now step into raise as 
expected. (That said, I did not double-check whether dwarf64 index 
always matches stabs index...)

Notice: This fix is absolutely necessary if you are working with Lazarus 
on Win64, as Lazarus automatically sets a breakpoint in fpc_raise... 
which then crashes gdb, which in turn crashes any running debugging 
session - in case an exception is raised. Of course it affects also all 
methods/funs that take e.g. three params that can be passed in regs...

Perhaps someone with more knowledge of stabs and the x86reg.dat can do a 
proper fix? TIA!

Cheers,
  Willi