widechar-enabled libedit problem on amd64

[Matthias Drochner <M.Drochner%fz-juelich.de@localhost>]

Hi -
a -current libedit crashes for me on amd64 if I attempt
tabcompletion, the stacktrace is:

#0  0x00007f7f00000000 in ?? ()
#1  0x00007f7ffd81738b in fn_complete (el=0x7f7ffdb22800,
    complet_func=0x7f7ffd817630 <fn_filename_completion_function>,
    attempted_completion_function=0, word_break=<value optimized out>,
    special_prefixes=<value optimized out>, app_func=0x7f7f00000000,
    query_items=100, completion_type=0x0, over=0x0, point=0x0, end=0x0)
    at /home/drochner/src/lib/libedit/filecomplete.c:473
#2  0x00007f7ffd817420 in _el_fn_complete (el=0x7f7ffdb03100,
    ch=<value optimized out>)
    at /home/drochner/src/lib/libedit/filecomplete.c:544
#3  0x00007f7ffd81a876 in el_wgets (el=0x7f7ffdb22800, nread=0x621b1c)
    at /home/drochner/src/lib/libedit/read.c:619
#4  0x00007f7ffd81ace2 in el_gets (el=0x7f7ffdb03100, nread=0x7f7ffdb030ed)
    at /home/drochner/src/lib/libedit/eln.c:76
#5  0x000000000040ba7e in preadbuffer ()
#6  0x00000000004129c1 in xxreadtoken ()
#7  0x0000000000412bc4 in readtoken ()
#8  0x0000000000412e57 in parsecmd ()
#9  0x000000000040e32a in cmdloop ()
#10 0x000000000040e6b9 in main ()

Note the app_func argument to fn_complete -- it should be NULL.
This looks like a compiler bug, see:

(gdb) x/20i _el_fn_complete
0x7f7ffd8173da <_el_fn_complete>:       sub    $0x28,%rsp
0x7f7ffd8173de <_el_fn_complete+4>:     movq   $0x0,0x20(%rsp)
0x7f7ffd8173e7 <_el_fn_complete+13>:    movq   $0x0,0x18(%rsp)
0x7f7ffd8173f0 <_el_fn_complete+22>:    movq   $0x0,0x10(%rsp)
0x7f7ffd8173f9 <_el_fn_complete+31>:    movq   $0x0,0x8(%rsp)
0x7f7ffd817402 <_el_fn_complete+40>:    movq   $0x64,(%rsp)
0x7f7ffd81740a <_el_fn_complete+48>:    xor    %r9d,%r9d
0x7f7ffd81740d <_el_fn_complete+51>:    xor    %r8d,%r8d
0x7f7ffd817410 <_el_fn_complete+54>:
    lea    2178057(%rip),%rcx        # 0x7f7ffda2b020
<rl_deprep_term_function+6
4>
0x7f7ffd817417 <_el_fn_complete+61>:    xor    %edx,%edx
0x7f7ffd817419 <_el_fn_complete+63>:    xor    %esi,%esi
0x7f7ffd81741b <_el_fn_complete+65>:    callq  0x7f7ffd808434 <fn_complete@plt>

The xor to registers clears only the lower 32 bits (in particular of r9).

Don't know what to do yet -- it doesn't crash if compiled without WIDECHAR,
or with -O0, although the generated code still looks as wrong as above.

best regards
Matthias



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