Re: [Gcl-devel] Re: possible GCL/Windows compiler bug

[Camm Maguire]

Greetings!

Matt Kaufmann <address@hidden> writes:

> Hi --
> 
> Thanks very much for the quick reply!  I have some questions.
> 
> When I tried gdb on ACL2/linux saved_acl2.gcl (built with GCL 2.6.5), and 
> executed
> 
>   gdb linux-gcl-saved_acl2.gcl
> 
> then I got the following unfortunate result (where I edited out the pathname):
> 
>   GNU gdb 5.3
>   Copyright 2002 Free Software Foundation, Inc.
>   GDB is free software, covered by the GNU General Public License, and you are
>   welcome to change it and/or distribute copies of it under certain 
> conditions.
>   Type "show copying" to see the conditions.
>   There is absolutely no warranty for GDB.  Type "show warranty" for details.
>   This GDB was configured as "i686-pc-linux-gnu"...(no debugging symbols 
> found)...
>   (gdb) b fasload
>   Function "fasload" not defined.
>   (gdb) r
>   Starting program: .../linux-gcl-saved_acl2.gcl 
>   (no debugging symbols found)...(no debugging symbols found)...(no debugging 
> symbols found)...
>   Program received signal SIGSEGV, Segmentation fault.
>   0x400c5d45 in memset () from /lib/libc.so.6
>   (gdb) 
> 

Forgot you have sgc on.  Do 'handle SIGSEGV nostop noprint' here and
continue with 'c'

> Is it necessary to build ACL2 with some special settings somehow in order to
> get debug info?
> 

In general, yes, but we can save time by checking quickly if we can
pinpoint the error in the mentioned function.  In general, we build
gcl with --enable-debug, but you can also get part of the way by
setting compiler::*c-debug* to t.

BTW, looking at the C source, I noticed native gcl support for set-mv
and mv-ref.  Nice to see these two projects so closely linked.

If/when you rebuild, please also do so with compiler::*default-c-file*
set to t so we can keep the generated C source just in case.  I
strongly doubt it is any different than what I can generate under
Linux. 

> In 4), how do you submit a Lisp LOAD command inside gdb?  Also, in 2), how do

Once you type 'r', you will have a lisp prompt.

> we arrange that r will run the particular commands that triggered the break?
> 

Starting in 3) issue commands to lisp as normal to trigger the
error. 'r' just starts acl2.

> General issue:  Recall that when we re-compile the match-clause function, the
> error goes away.  Doesn't that suggest that your approach won't trigger the
> error in 8)?
> 

Missed this somehow.  If it does not trigger the error, then trigger
it from gdb running acl2/lisp as you know how, send the backtrace,
send objdump -d basis.o, find the address (printed) where basis.o was
loaded, find out the address where the fault occurs, and 'p/x *(char
*)<basis.o load address>@1024', 'p/x *((char *)<basis.o load
address>+1024)@1024', etc. until you print out the address of the
fault.  You may have difficulty locating the fault address with sgc
on.  See if you can retain the error with sgc turned off.  If not,
then 'b sgbc.c:1626' and 'cond 1 fault_count > 300' (assuming the
breakpoint just created was numbered 1, and 'b segmentation_catcher'.
You can then see the fault address in the backtrace (bt) printed under
gdb. 

Take care,

> Thanks --
> -- Matt
>    Cc: address@hidden, "Mike Thomas" <address@hidden>,
>          address@hidden
>    From: Camm Maguire <address@hidden>
>    Date: 12 Oct 2004 10:40:23 -0400
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> 
>    Greetings!
> 
>    OK, my suspicion lies with a difficulty in the windows relocation
>    code, but I'm not yet certain.  Here is how to proceed:
> 
>    0) run saved_acl2 under gdb 
> 
>    1) b fasload
> 
>    2) r
> 
>    3) Put your match-clause function into a separate file, compile with
>       compiler::*c-debug* set to t
> 
>    4) (load "your_file.o")
> 
>    5) gdb will break -- type 'finish'
> 
>    6) Still at gdb prompt, look at start address printed by gcl to
>       screen.  Type 'add-symbol-file <your_file.o> <address>
> 
>    7) c
> 
>    8) trigger the error
> 
>    9) gdb will stop, print a backtrace with bt
> 
>    10) In gdb, type 'p/x *(char *)<address>@1024'
> 
>    11) In gdb, type 'shell', and then 'objdump -d your_file.o'
> 
>    12) Send me the results
> 
>    Take care,
> 
> 
>    Matt Kaufmann <address@hidden> writes:
> 
>    > [Resending -- I had a typo in the CC field that may have prevented 
> delivery.]
>    > 
>    > Hi --
>    > 
>    > Help!?  Sorry to bother you with this email, but I've gone about as far 
> as I
>    > know how with the problem described below (and I'll spare you the dead 
> ends),
>    > which I kind of suspect is a problem with GCL/Windows, but might instead 
> be a
>    > problem with ACL2.  This is a rather long email; please feel free to ask 
> for
>    > any clarification.
>    > 
>    > There appears to be a problem either with GCL on Windows or with ACL2.  
> I'll
>    > describe the symptom below.  This symptom doesn't occur on Linux or 
> Sun/Solaris
>    > for GCL, Allegro CL, CMUCL, or CLISP, and I also haven't seen it on 
> Linux with
>    > Lispworks or on a Macintosh with OpenMCL; I've only seen it on 
> GCL/Windows.
>    > But I realize that it still could be a subtle problem with ACL2, so I 
> think we
>    > need to wait on the ACL2 release until we determine whether or not it's a
>    > GCL/Windows problem.
>    > 
>    > Jared Davis was kind enough to submit the commands below (at the end of 
> this
>    > email) while standing in directory books/misc/ of the ACL2 distribution, 
> after
>    > building ACL2 on GCL/Windows 2.6.5.  The result is a hard Lisp error if 
> you do
>    > *NOT* submit the compile form below: for a transcript, see
>    > http://www.cs.utexas.edu/users/jared/test.log5 (or equivalently, on the 
> UTCS
>    > file system, /u/www/users/jared/test.log5).  But *with* the compile 
> form, the
>    > problem goes away (see test.log4 in the same directory).  We verified 
> that the
>    > definition being compiled is exactly the same as the one compiled when 
> building
>    > ACL2.  (I'll explain how if you're interested -- we could insert a call 
> of
>    > disassemble during the build if you think that would be helpful.)
>    > 
>    > You can see the result of :bt and :ihs on a failed run, where some source
>    > functions are run interpreted (but this doesn't avoid the error since the
>    > offending function ACL2_*1*_ACL2::MATCH-CLAUSE is still run compiled), in
>    > test.log in that same directory.  In a moment I'll forward you a related 
> log
>    > with that info (and also the result of :bl), in case you prefer to see 
> it by
>    > email.
>    > 
>    > By the way, all of the failures Jared came across during the regression 
> run
>    > were during macroexpansion of ACL2 macro case-match, which calls
>    > match-clause-list, which calls match-clause -- actually the ACL2 
> macroexpansion
>    > mechanism causes a call of ACL2_*1*_ACL2::MATCH-CLAUSE-LIST, which calls
>    > ACL2_*1*_ACL2::MATCH-CLAUSE.
>    > 
>    > Also by the way, even if you leave off the compile form below but you add
>    > (si::use-fast-links nil), the problem goes away.  That seems odd to me 
> so I
>    > thought I should mention it.
>    > 
>    > Here are the commands after starting up ACL2.  Again, omit the compile 
> form to
>    > see the error -- even though the compile form should be a no-op!
>    > 
>    > (rebuild "defpun.lisp" 'arbitrary-tail-recursive-encap)
>    > :q
>    > (compile
>    >  (DEFUN ACL2_*1*_ACL2::MATCH-CLAUSE (X PAT FORMS)
>    >    (COND
>    >     ((F-GET-GLOBAL 'SAFE-MODE *THE-LIVE-STATE*)
>    >      (RETURN-FROM
>    >       ACL2_*1*_ACL2::MATCH-CLAUSE
>    >       (MV-LET (TESTS BINDINGS)
>    >               (ACL2_*1*_ACL2::MATCH-TESTS-AND-BINDINGS X PAT NIL NIL)
>    >               (LIST (IF (ACL2_*1*_COMMON-LISP::NULL TESTS) T
>    >                         (CONS 'AND
>    >                               (ACL2_*1*_COMMON-LISP::REVERSE TESTS)))
>    >                     (CONS 'LET
>    >                           (CONS (ACL2_*1*_COMMON-LISP::REVERSE
>    >                                  BINDINGS)
>    >                                 FORMS)))))))
>    >    (MATCH-CLAUSE X PAT FORMS)))
>    > (lp)
>    > (defun remove-xargs-domain-and-measure (dcl)
>    >   (case-match dcl
>    >     (('declare ('xargs ':domain dom-expr
>    >                        ':measure measure-expr
>    >                        . rest))
>    >      (mv nil dom-expr measure-expr rest))
>    >     (('declare ('xargs ':gdomain dom-expr
>    >                        ':measure measure-expr
>    >                        . rest))
>    >      (mv t dom-expr measure-expr rest))
>    >     (& (mv nil nil 0 nil))))
>    > 
>    > Thanks much --
>    > -- Matt
>    > 
>    > 
>    > 
> 
>    -- 
>    Camm Maguire                                               address@hidden
>    ==========================================================================
>    "The earth is but one country, and mankind its citizens."  --  Baha'u'llah
> 
> 
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> 

-- 
Camm Maguire                                            address@hidden
==========================================================================
"The earth is but one country, and mankind its citizens."  --  Baha'u'llah