Re: [fpc-devel] x86_64 stabs info - patch (sort of)
Am 12.10.2010 01:04, schrieb 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 FUN0 18700408710 66408 fpc_raiseexception:F129 4944 RSYM 0 6250001 66432 OBJ:R129 4945 RSYM 0 6250002 66441 ANADDR:R4 4946 RSYM 0 625 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=1.18content-type=text/x-cvsweb-markupcvsroot=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! Afaik, stabs does not support x86-64 that's why it's probably never fixed/noticed. ___ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
Re: [fpc-devel] x86_64 stabs info - patch (sort of)
On 12 Oct 2010, at 09:25, Florian Klaempfl wrote: Afaik, stabs does not support x86-64 that's why it's probably never fixed/noticed. The problem is that for some reason, it's nevertheless the default for Win64. Jonas ___ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
RE: [fpc-devel] x86_64 stabs info - patch (sort of)
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! Afaik, stabs does not support x86-64 that's why it's probably never fixed/noticed. This is not true: I src/gdb/amd64-tdep.c you can see this (line 2419 on current CVS): /* The default register numbering scheme for AMD64 is referred to as the DWARF Register Number Mapping in the System V psABI. The preferred debugging format for all known AMD64 targets is actually DWARF2, and GCC doesn't seem to support DWARF (that is DWARF-1), but we provide the same mapping just in case. This mapping is also used for stabs, which GCC does support. */ set_gdbarch_stab_reg_to_regnum (gdbarch, amd64_dwarf_reg_to_regnum); set_gdbarch_dwarf2_reg_to_regnum (gdbarch, amd64_dwarf_reg_to_regnum); This means that indeed stabs and dwarf register number are equal, at least for GDB. The problem is that this means that we probably also need to distinguish between stabs32 and stabs64, as we already do for dwarf32 and dwarf64... unless we change the code that reads x86reg.dat to use dwarf64 indexes for amd64 stabs registers. Pierre ___ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
Re: [fpc-devel] x86_64 stabs info - patch (sort of)
On 12 Oct 2010, at 10:25, Pierre Free Pascal wrote: This means that indeed stabs and dwarf register number are equal, at least for GDB. The problem is that this means that we probably also need to distinguish between stabs32 and stabs64, as we already do for dwarf32 and dwarf64... There is no stabs64 format, afaik. See http://sourceware.org/bugzilla/show_bug.cgi?id=9327 Jonas ___ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
Re: [fpc-devel] x86_64 stabs info - patch (sort of)
Am 12.10.2010 09:51, schrieb Jonas Maebe:
There is no stabs64 format, afaik. See
http://sourceware.org/bugzilla/show_bug.cgi?id=9327
Just checked, this example is working fine on Win64:
PS C:\source\bugs\lokals gdb test.exe
GNU gdb (GDB) 7.2
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
http://gnu.org/licenses/gpl.html
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type show copying
and show warranty for details.
This GDB was configured as x86_64-w64-mingw32.
For bug reporting instructions, please see:
http://www.gnu.org/software/gdb/bugs/...
Reading symbols from C:\source\bugs\lokals/test.exe...done.
(gdb) break MAINPROC
Breakpoint 1 at 0x40140c: file test.pp, line 5.
(gdb) run
Starting program: C:\source\bugs\lokals/test.exe
[New Thread 8148.0x9a8]
Breakpoint 1, MAINPROC () at test.pp:5
5 x := 5;
(gdb) step
6 writeln('x=',x);
(gdb) print x
$1 = 5
(gdb)
In any case, register indices and offsets are different matters and as
it seems that DWARF indices are fine for stabs, I'd strongly vote for
fixing x86_64 stabs info.
Cheers,
Willi
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RE: [fpc-devel] x86_64 stabs info - patch (sort of)
-Message d'origine- De : fpc-devel-boun...@lists.freepascal.org [mailto:fpc-devel- boun...@lists.freepascal.org] De la part de Jonas Maebe Envoyé : Tuesday, October 12, 2010 10:51 AM À : FPC developers' list Objet : Re: [fpc-devel] x86_64 stabs info - patch (sort of) On 12 Oct 2010, at 10:25, Pierre Free Pascal wrote: This means that indeed stabs and dwarf register number are equal, at least for GDB. The problem is that this means that we probably also need to distinguish between stabs32 and stabs64, as we already do for dwarf32 and dwarf64... There is no stabs64 format, afaik. See http://sourceware.org/bugzilla/show_bug.cgi?id=9327 I think that dwarf32 and dwarf64 here only refers to i386 32-bit registers versus amd64 64-bit registers. It is in that meaning that I said that we should use the dwarf64 column of x86reg.dat to implement the stabs register number for x86_64 CPU. Pierre ___ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
RE: [fpc-devel] x86_64 stabs info - patch (sort of)
-Message d'origine- De : fpc-devel-boun...@lists.freepascal.org [mailto:fpc-devel- boun...@lists.freepascal.org] De la part de Jonas Maebe Envoyé : Tuesday, October 12, 2010 10:00 AM À : FPC developers' list Objet : Re: [fpc-devel] x86_64 stabs info - patch (sort of) On 12 Oct 2010, at 09:25, Florian Klaempfl wrote: Afaik, stabs does not support x86-64 that's why it's probably never fixed/noticed. The problem is that for some reason, it's nevertheless the default for Win64. It currently is because dwarf debug information generation for x86_64 is still much more buggy than stabs generation. Pierre ___ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
Re: [fpc-devel] x86_64 stabs info - patch (sort of)
On 12 Oct 2010, at 11:49, Pierre Free Pascal wrote: -Message d'origine- De : fpc-devel-boun...@lists.freepascal.org [mailto:fpc-devel- boun...@lists.freepascal.org] De la part de Jonas Maebe Envoyé : Tuesday, October 12, 2010 10:00 AM À : FPC developers' list Objet : Re: [fpc-devel] x86_64 stabs info - patch (sort of) On 12 Oct 2010, at 09:25, Florian Klaempfl wrote: Afaik, stabs does not support x86-64 that's why it's probably never fixed/noticed. The problem is that for some reason, it's nevertheless the default for Win64. It currently is because dwarf debug information generation for x86_64 is still much more buggy than stabs generation. Is it? I use it all the time on Mac OS X/x86-64 and Linux/x86-64, and it works fine. Jonas___ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
RE: [fpc-devel] x86_64 stabs info - patch (sort of)
-Message d'origine- De : fpc-devel-boun...@lists.freepascal.org [mailto:fpc-devel- boun...@lists.freepascal.org] De la part de Jonas Maebe Envoyé : Tuesday, October 12, 2010 11:56 AM À : FPC developers' list Objet : Re: [fpc-devel] x86_64 stabs info - patch (sort of) On 12 Oct 2010, at 11:49, Pierre Free Pascal wrote: -Message d'origine- De : fpc-devel-boun...@lists.freepascal.org [mailto:fpc-devel- boun...@lists.freepascal.org] De la part de Jonas Maebe Envoyé : Tuesday, October 12, 2010 10:00 AM À : FPC developers' list Objet : Re: [fpc-devel] x86_64 stabs info - patch (sort of) On 12 Oct 2010, at 09:25, Florian Klaempfl wrote: Afaik, stabs does not support x86-64 that's why it's probably never fixed/noticed. The problem is that for some reason, it's nevertheless the default for Win64. It currently is because dwarf debug information generation for x86_64 is still much more buggy than stabs generation. Is it? I use it all the time on Mac OS X/x86-64 and Linux/x86-64, and it works fine. It might be specific to win64, especially the internal linker. I only tested win64 target, the others might be OK. Note that a recent fix by Willibald Krenn might have improved things a lot, but I didn't have much time to check it out yet. Pierre ___ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
RE: [fpc-devel] x86_64 stabs info - patch (sort of)
-Message d'origine- De : fpc-devel-boun...@lists.freepascal.org [mailto:fpc-devel- boun...@lists.freepascal.org] De la part de Jonas Maebe Envoyé : Tuesday, October 12, 2010 10:51 AM À : FPC developers' list Objet : Re: [fpc-devel] x86_64 stabs info - patch (sort of) On 12 Oct 2010, at 10:25, Pierre Free Pascal wrote: This means that indeed stabs and dwarf register number are equal, at least for GDB. The problem is that this means that we probably also need to distinguish between stabs32 and stabs64, as we already do for dwarf32 and dwarf64... There is no stabs64 format, afaik. See http://sourceware.org/bugzilla/show_bug.cgi?id=9327 This is also not totally true: I heard recently that Apple has a 64-bit extension of the stabs debug format in bfd/mach-o.c:bfd_mach_o_read_symtab_symbol and gdb/machoread.c:macho_symtab_read (this doesn't use dbxread.c) Pierre ___ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
Re: [fpc-devel] x86_64 stabs info - patch (sort of)
On 12 Oct 2010, at 12:14, Pierre Free Pascal wrote: There is no stabs64 format, afaik. See http://sourceware.org/bugzilla/show_bug.cgi?id=9327 This is also not totally true: I heard recently that Apple has a 64-bit extension of the stabs debug format in bfd/mach-o.c:bfd_mach_o_read_symtab_symbol and gdb/machoread.c:macho_symtab_read (this doesn't use dbxread.c) That's true, but a) afaik it's only supported on Mac OS X b) our Stabs writer does not support those extensions (I initially tried using Stabs on Mac OS X 64 bit because back then DWARF support in FPC was not very good, but changing the Stabs writer seemed more work than improving the DWARF support) Jonas ___ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
Re: [fpc-devel] x86_64 stabs info - patch (sort of)
Am 12.10.2010 10:55, schrieb Jonas Maebe: It currently is because dwarf debug information generation for x86_64 is still much more buggy than stabs generation. Is it? I use it all the time on Mac OS X/x86-64 and Linux/x86-64, and it works fine. DWARF does not work on Win64: while dwarf3 produces an internal error (2010092801, sounds familiar ;-)), dwarf2 debug information seems to be broken too. At least gdb 7.2 reports invalid offsets. Hence for the time being, stabs is the only option and better than nothing. Therefore I'd really love to see the register indices changed. Thanks, Willi ___ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
Re: [fpc-devel] x86_64 stabs info - patch (sort of)
On 12 Oct 2010, at 21:26, Willibald Krenn wrote: Am 12.10.2010 10:55, schrieb Jonas Maebe: It currently is because dwarf debug information generation for x86_64 is still much more buggy than stabs generation. Is it? I use it all the time on Mac OS X/x86-64 and Linux/x86-64, and it works fine. DWARF does not work on Win64: while dwarf3 produces an internal error (2010092801, sounds familiar ;-)), DWARF3 is not yet really tested. dwarf2 debug information seems to be broken too. Keep this in mind: http://bugs.freepascal.org/view.php?id=15692 You may also want to try with the external linker (-Xe). Jonas___ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
Re: [fpc-devel] x86_64 stabs info - patch (sort of)
Am 12.10.2010 20:33, schrieb Jonas Maebe: dwarf2 debug information seems to be broken too. Keep this in mind: http://bugs.freepascal.org/view.php?id=15692 I don't know exactly what to conclude from this discussion. Are 32 bit pointers enough for WinPE? Then stabs would be fine anyways. You may also want to try with the external linker (-Xe). Hmm, -Xe does not seem to work on my system. So, stabs remains the only thing that is working. (Even if it has limitations it is better than 0.) Cheers, Willi ___ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
Re: [fpc-devel] x86_64 stabs info - patch (sort of)
On 12 Oct 2010, at 21:55, Willibald Krenn wrote: Am 12.10.2010 20:33, schrieb Jonas Maebe: dwarf2 debug information seems to be broken too. Keep this in mind: http://bugs.freepascal.org/view.php?id=15692 I don't know exactly what to conclude from this discussion. Try using the -WB004 command line option. Are 32 bit pointers enough for WinPE? Then stabs would be fine anyways. The problem is that GDB (at least in the past) zero-extends all offsets in the stabs debug information. That means that a local variable at location ebp-16 is interpreted as being at location ebp+4294967280. There are probably more such small problems, because Stabs was never designed nor implemented to be used for 64 bit platforms within the GNU tool chain. You may also want to try with the external linker (-Xe). Hmm, -Xe does not seem to work on my system. What does not work mean? So, stabs remains the only thing that is working. (Even if it has limitations it is better than 0.) I'm not opposed to committing that change, it's just that Stabs is a dead end and since no compiler I know of uses it for generating 64 bit debug information (other than a few older Mac OS X compilers, but Mac OS X uses its own fork of GDB), it's probably also very badly tested within GDB itself. Jonas___ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
Re: [fpc-devel] x86_64 stabs info - patch (sort of)
Am 12.10.2010 21:02, schrieb Jonas Maebe:
I don't know exactly what to conclude from this discussion.
Try using the -WB004 command line option.
PS C:\source\bugs\exception del *.o
PS C:\source\bugs\exception del *.exe
PS C:\source\bugs\exception fpc -gw -WB004 .\project1.lpr
PS C:\source\bugs\exception gdb .\project1.exe
(gdb) list
invalid dwarf2 offset 504164
(gdb)
Are 32 bit pointers enough for WinPE? Then stabs would be fine anyways.
The problem is that GDB (at least in the past) zero-extends all offsets
in the stabs debug information. That means that a local variable at
location ebp-16 is interpreted as being at location ebp+4294967280.
There are probably more such small problems, because Stabs was never
designed nor implemented to be used for 64 bit platforms within the GNU
tool chain.
At least on my system, having stabs info like the following
58 FUN0 18 00401540 3216 RAISEEXCEPTION:F1
59 PSYM 0 20 fff8 3234 A:5
60 PSYM 0 21 fff0 3238 B:5
61 PSYM 0 22 ffe8 3242 C:5
62 PSYM 0 23 ff90 3246 D:6
63 PSYM 0 24 ff88 3250 E:7
64 SOL0 0 00401540 3254 project1.lpr
yields
Breakpoint 2, RAISEEXCEPTION () at project1.lpr:44
44raise EAbort.Create('test');
(gdb) info locals
A = 20
B = 1
C = 2
D = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
19, 20}
E = 0x42c150 'Hello World!'
which is quite ok ;-).
You may also want to try with the external linker (-Xe).
Hmm, -Xe does not seem to work on my system.
What does not work mean?
Sorry, I meant to say that it does not improve the situation.
PS C:\source\bugs\exception del *.o
PS C:\source\bugs\exception del *.exe
PS C:\source\bugs\exception fpc -gw -Xe .\project1.lpr
[0.578] Using util C:\source\mingw64\bin\ld.exe
PS C:\source\bugs\exception gdb .\project1.exe
(gdb) list
invalid dwarf2 offset 6439543
I'm not opposed to committing that change, it's just that Stabs is a
dead end and since no compiler I know of uses it for generating 64 bit
debug information (other than a few older Mac OS X compilers, but Mac OS
X uses its own fork of GDB), it's probably also very badly tested within
GDB itself.
Yes, I understand that stabs is a dead-end. But it's also very useful if
you want to work with the compiler on Win64 :)
Cheers,
Willi
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Re: [fpc-devel] x86_64 stabs info - patch (sort of)
On 12 Oct 2010, at 22:31, Willibald Krenn wrote: PS C:\source\bugs\exception del *.o PS C:\source\bugs\exception del *.exe PS C:\source\bugs\exception fpc -gw -WB004 .\project1.lpr PS C:\source\bugs\exception gdb .\project1.exe (gdb) list invalid dwarf2 offset 504164 That seems like this bug report: http://bugs.freepascal.org/view.php?id=16297 I can't help any further with that since I don't develop for/under Windows though. Jonas___ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
