[clisp-list] Re: CVS head - Crash dump on Mac OS X 10.4.3

[Johan L. <jo...@li...>]

On Nov 21, 2005, at 19:22, Sam Steingold wrote:

> SUMMARY:
>
> segfault on startup in closed_buffered() when built with "gcc -O2"
>
> Exception:  EXC_BAD_ACCESS (0x0001)
> Codes:      KERN_PROTECTION_FAILURE (0x0002) at 0x19fb6130
>
> Thread 0 Crashed:
> 0   lisp.run 	0x0006f8b4 closed_buffered + 48 (crt.c:355)
> 1   lisp.run 	0x0007850c closed_all_files + 108 (crt.c:355)
> 2   lisp.run 	0x000289ac loadmem_from_handle + 3168 (crt.c:355)
> 3   lisp.run 	0x00028c68 loadmem + 128 (crt.c:355)
> 4   lisp.run 	0x00029058 init_memory + 888 (crt.c:355)
> 5   lisp.run 	0x0002b610 main + 3940 (crt.c:355)
> 6   lisp.run 	0x00002878 _start + 340 (crt.c:272)
> 7   lisp.run 	0x00002720 start + 60
>
> no segfault when built with "gcc -g"
>
> is this correct?

Correct, but see below.


> my current conjecture is that this is a GCC bug.

I think you may be right; I recently upgraded to Apples Xcode Tools  
2.2, which includes GCC 4.0.1. Before (this thread) I have been using  
GCC 4.0.0.

I now also recompiled CLISP 2.35 using GCC 4.0.1, which also gives  
the segfault (sorry for not figuring that out earlier).

> gcc --version

powerpc-apple-darwin8-gcc-4.0.1 (GCC) 4.0.1 (Apple Computer, Inc.  
build 5247)

> uname -a

Darwin Johans-Computer.local 8.3.0 Darwin Kernel Version 8.3.0: Mon  
Oct  3 20:04:04 PDT 2005; root:xnu-792.6.22.obj~2/RELEASE_PPC Power  
Macintosh powerpc


> could you please figure out which optimization switch causes this?
> you will need to
> 1. configure as usual (no "--with-debug")
> 2. build, make sure that you get the crash.
> 3. edit build/Makefile and change CFLAGS, removing some optimization
>    flags
> 4. build again and see if you get the crash.
>
> when you find the specific optimization flag that causes the crash,
> please report it here so that makemake will omit it on macos.

The "-DSAFETY=3" seems to do the trick. Adding this flag to the  
original CFLAGS gives a build that does not crash.

The CFLAGS that works for me looks like:

CFLAGS = -W -Wswitch -Wcomment -Wpointer-arith -Wimplicit -Wreturn- 
type -Wmissing-declarations -Wno-sign-compare -O2 -DSAFETY=3 - 
DUNIX_BINARY_DISTRIB -DUNICODE -DDYNAMIC_FFI -I.


I also tried all the combinations below, and they all segfault:

* "gcc -O"
* "gcc" (no optimaztion)
* "gcc -falign-functions=4" (no optimization)
* "gcc -falign-functions=4 -g"


-- 
Johan Liseborn