This is reproducible with an i686 cross.
build/genextract ../../src-head/gcc/config/rs6000/rs6000.md \
insn-conditions.md > tmp-extract.c
*** glibc detected *** build/genextract: double free or corruption (fasttop):
0x081cc980 ***
======= Backtrace: =========
/lib/libc.so.6[0x9da124]
/lib/libc.so.6(__libc_free+0x77)[0x9da65f]
build/genextract[0x80499af]
/lib/libc.so.6(__libc_start_main+0xdf)[0x98bd5f]
build/genextract(free+0x91)[0x8048c39]
======= Memory map: ========
00959000-00973000 r-xp 00000000 fd:00 1081346 /lib/ld-2.3.5.so
00973000-00974000 r-xp 00019000 fd:00 1081346 /lib/ld-2.3.5.so
00974000-00975000 rwxp 0001a000 fd:00 1081346 /lib/ld-2.3.5.so
00977000-00a9a000 r-xp 00000000 fd:00 1081362 /lib/libc-2.3.5.so
00a9a000-00a9c000 r-xp 00123000 fd:00 1081362 /lib/libc-2.3.5.so
00a9c000-00a9e000 rwxp 00125000 fd:00 1081362 /lib/libc-2.3.5.so
00a9e000-00aa0000 rwxp 00a9e000 00:00 0
00c86000-00c87000 r-xp 00c86000 00:00 0 [vdso]
00df3000-00dfc000 r-xp 00000000 fd:00 1081381
/lib/libgcc_s-4.0.2-20051126.so.1
00dfc000-00dfd000 rwxp 00009000 fd:00 1081381
/lib/libgcc_s-4.0.2-20051126.so.1
08048000-08057000 r-xp 00000000 fd:01 10552009
/local/rth/gcc/bld-ppc/gcc/build/genextract
08057000-08058000 rw-p 0000e000 fd:01 10552009
/local/rth/gcc/bld-ppc/gcc/build/genextract
08058000-081da000 rw-p 08058000 00:00 0 [heap]
b7e00000-b7e21000 rw-p b7e00000 00:00 0
b7e21000-b7f00000 ---p b7e21000 00:00 0
b7ff1000-b7ff2000 rw-p b7ff1000 00:00 0
b7fff000-b8000000 rw-p b7fff000 00:00 0
bffea000-c0000000 rw-p bffea000 00:00 0 [stack]
/bin/sh: line 1: 26254 Aborted build/genextract
../../src-head/gcc/config/rs6000/rs6000.md insn-conditions.md >tmp-extract.c
#0 0x0fee6548 in free () from /lib/libc.so.6
#1 0x10001414 in VEC_locstr_heap_free (vec_=0xffe2d5d8)
at ../../src-head/gcc/genextract.c:77
#2 0x100012dc in gen_insn (insn=0x100f3ff0, insn_code_number=339)
at ../../src-head/gcc/genextract.c:179
#3 0x10002e60 in main (argc=3, argv=0xffe2d8e4)
at ../../src-head/gcc/genextract.c:418
r~
