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

From: Matt Kaufmann
Subject: Re: [Gcl-devel] Re: possible GCL/Windows compiler bug
Date: Tue, 12 Oct 2004 14:44:59 -0500

Here is some additional information that I think will affect how you want to

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

(in-package "ACL2")

               (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

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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   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 
   >   gdb linux-gcl-saved_acl2.gcl
   > then I got the following unfortunate result (where I edited out the 
   >   GNU gdb 5.3
   >   Copyright 2002 Free Software Foundation, Inc.
   >   GDB is free software, covered by the GNU General Public License, and you 
   >   welcome to change it and/or distribute copies of it under certain 
   >   Type "show copying" to see the conditions.
   >   There is absolutely no warranty for GDB.  Type "show warranty" for 
   >   This GDB was configured as "i686-pc-linux-gnu"...(no debugging symbols 
   >   (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 
   > 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

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

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

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

   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, 
   > 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

   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 
   >    > 
   >    > 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 
   >    > 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 
   >    > 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 
   >    > functions are run interpreted (but this doesn't avoid the error since 
   >    > 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 
   >    > mechanism causes a call of ACL2_*1*_ACL2::MATCH-CLAUSE-LIST, which 
   >    > ACL2_*1*_ACL2::MATCH-CLAUSE.
   >    > 
   >    > Also by the way, even if you leave off the compile form below but you 
   >    > (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
   >    >    (COND
   >    >      (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."  --  
   > _______________________________________________
   > Gcl-devel mailing list
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   > http://lists.gnu.org/mailman/listinfo/gcl-devel

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

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