bug#45214: guile segfaults on 32-bit big-endian targets

Hello!

As reported in [1], guile segfaults on 32-bit big-endian targets with:

guild compile --target="hppa-unknown-linux-gnu"                \
          -W0 -O1              \
  -L "/<<PKGBUILDDIR>>/module"                         \
  -L "/<<PKGBUILDDIR>>/guile-readline"			\
  -o "language/tree-il/eta-expand.go" "../module/language/tree-il/eta-expand.scm"
make[4]: *** [Makefile:1927: language/tree-il/eta-expand.go] Segmentation fault
make[4]: *** Waiting for unfinished jobs....
make[4]: *** [Makefile:1927: language/tree-il/debug.go] Segmentation fault
make[4]: *** [Makefile:1927: language/tree-il/analyze.go] Segmentation fault
still going
make[4]: *** [Makefile:1927: language/tree-il/effects.go] Segmentation fault
make[4]: Leaving directory '/<<PKGBUILDDIR>>/bootstrap'
make[3]: *** [Makefile:1851: all-recursive] Error 1
make[3]: Leaving directory '/<<PKGBUILDDIR>>'
make[2]: *** [Makefile:1737: all] Error 2
make[2]: Leaving directory '/<<PKGBUILDDIR>>'
make[1]: *** [debian/rules:192: override_dh_auto_build] Error 2
make[1]: Leaving directory '/<<PKGBUILDDIR>>'
make: *** [debian/rules:104: build-arch] Error 2
dpkg-buildpackage: error: debian/rules build-arch subprocess returned exit status 2

Full build log in [2]. This affects hppa, m68k and powerpc (32-bit).

Backtrace:

#0  0x006e3e9c in scm_sum (x=x@entry=0x0, y=0x6) at numbers.c:7569
7569      else if (SCM_BIGP (x))
[Current thread is 1 (Thread 0xf7c34480 (LWP 529732))]
(gdb) bt
#0  0x006e3e9c in scm_sum (x=x@entry=0x0, y=0x6) at numbers.c:7569
#1  0x006cd498 in add_immediate (a=0x0, b=<optimized out>) at intrinsics.c:80
#2  0x00749818 in vm_regular_engine (thread=0xf7971e00) at vm-engine.c:1583
#3  0x0074c2f4 in scm_call_n (proc=proc@entry=0xeffbf148, argv=argv@entry=0x0, 
nargs=nargs@entry=0) at vm.c:1608
#4  0x006a70fc in scm_call_0 (proc=proc@entry=0xeffbf148) at eval.c:490
#5  0x006d39d8 in scm_primitive_load_path (args=<optimized out>) at load.c:1259
#6  0x006d3f28 in scm_c_primitive_load_path (filename=filename@entry=0x776458 
"ice-9/boot-9") at load.c:1275
#7  0x006c9310 in scm_load_startup_files () at init.c:222
#8  0x006c96a8 in scm_i_init_guile (base=base@entry=0xffecfb18) at init.c:505
#9  0x0073b858 in scm_i_init_thread_for_guile (base=base@entry=0xffecfb18, 
dynamic_state=dynamic_state@entry=0x0) at threads.c:570
#10 0x0073ba1c in scm_i_init_thread_for_guile (dynamic_state=0x0, 
base=0xffecfb18) at threads.c:677
#11 with_guile (base=0xffecfb18, data=0xffecfb38) at threads.c:638
#12 0x003e17e4 in GC_call_with_stack_base () from 
/usr/lib/powerpc-linux-gnu/libgc.so.1
#13 0x0073bfb8 in scm_i_with_guile (dynamic_state=<optimized out>, 
data=0xffecfb28, func=0x6c90c0 <invoke_main_func>) at threads.c:688
#14 scm_with_guile (func=func@entry=0x6c90c0 <invoke_main_func>, 
data=data@entry=0xffecfb58) at threads.c:694
#15 0x006c93c8 in scm_boot_guile (argc=argc@entry=16, 
argv=argv@entry=0xffecfe14, main_func=main_func@entry=0x800950 <inner_main>, 
closure=closure@entry=0x0) at init.c:290
#16 0x00800754 in main (argc=16, argv=0xffecfe14) at guile.c:95
(gdb)

I assume the crash has got something to do how values are packed and unpacked
into the SCM object type. I have not been able to find the problem yet myself,
unfortunately which is why I am reporting this issue here.

For anyone willing to debug this, access to a fast POWER machine running a
big-endian Debian unstable can be obtained through the GCC compile farm [3].

Thanks,
Adrian

> [1] https://lists.gnu.org/archive/html/guile-devel/2020-12/msg00003.html
> [2] https://buildd.debian.org/status/fetch.php?pkg=guile-3.0&arch=hppa&ver=3.0.4-3&stamp=1607546304&raw=0
> [3] https://gcc.gnu.org/wiki/CompileFarm

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - [email protected]
`. `'   Freie Universitaet Berlin - [email protected]
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913