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

[Camm Maguire]

Greetings!  Bugs like this are often elusive.  I suggest seeing if you
can reproduce simply with sgc off.  If so, rerun the error under gdb,
and send me the backtrace.  If not, leave sgc on in the gdb run, do
the 'handle SIGSEGV' to avoid stopping at every fault, then break 
at sgbc.c:1626 and segmentation_catcher, run, reproduce the error, and
send the backtrace.  Try to find the address of the fault, and if
possible, cross reference it with one of the addresses printed out on
object module load.

After this, to save time, try building acl2 again *somewhere else,
i.e. save this build*, with --enable-debug passed to gcl.  See if the
bug persists.  If so, more info will be available from the above when
run here.

Take care,

Matt Kaufmann <address@hidden> writes:

> Here is some additional information that I think will affect how you want to
> proceed.
> 
> First of all, the offending function, ACL2_*1*_ACL2::MATCH-CLAUSE, isn't
> defined in basis.lisp (unlike ACL2::MATCH-CLAUSE, which _is_ defined in
> basis.lisp).  Rather, the definition, def, of ACL2_*1*_ACL2::MATCH-CLAUSE is
> generated and compiled on the fly during the build, with (eval def) and
> (eval `(compile ',(cadr def))).
> 
> So, loading basis.o presumably won't help.  Instead, I hacked the build
> procedure so that for ACL2_*1*_ACL2::MATCH-CLAUSE, we write out a file
> my-debug.lisp:
> 
> ===============================================================================
> (in-package "ACL2")
> 
> (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))
> ===============================================================================
> 
> Instead of (eval `(compile ',(cadr def))), the hacked build code does the
> following during the build:
> 
> (compile-file "my-debug.lisp" :c-file t :h-file t)
> (load "my-debug")
> 
> I figured that this is what you'd need in order to carry out your plan.
> 
> Jared Davis graciously ran this experiment.  Unfortunately, with that small
> change in the build procedure the problem goes away.  (I suppose we could
> change ACL2 to do this for all functions, but it seems unfortunate to do all
> that unnecessary file io, and I wonder if that would mask some other issue.)
> 
> So, how would you like to proceed?
> 
> Thanks --
> -- Matt
>    Cc: address@hidden, address@hidden
>    From: Camm Maguire <address@hidden>
>    Date: 12 Oct 2004 11:59:34 -0400
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> 
>    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
> 
> 

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