https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61871
--- Comment #2 from Uroš Bizjak <ubizjak at gmail dot com> --- The backtrace mentions "malloc/free - deadlock" and the segmentation fault happens later: Program received signal SIGSEGV, Segmentation fault. [Switching to Thread 0x200011d3270 (LWP 18336)] 0x0000020000e8bbac in memmove () from /lib/libc.so.6.1 (gdb) bt #0 0x0000020000e8bbac in memmove () from /lib/libc.so.6.1 #1 0x00000200005b3a84 in gwrite (v=0x200009372f0, n=19) at /home/uros/gcc-svn/trunk/libgo/runtime/print.c:38 #2 0x00000200005b4868 in runtime_printf (s=0x200008eab4c <regexp_syntax.rune.pN22_regexp_syntax.compiler+204> ">") at /home/uros/gcc-svn/trunk/libgo/runtime/print.c:96 #3 0x00000200005b3014 in runtime_startpanic () at /home/uros/gcc-svn/trunk/libgo/runtime/panic.c:97 #4 0x00000200005b3160 in runtime_throw (s=0x2000093820c "malloc/free - deadlock") at /home/uros/gcc-svn/trunk/libgo/runtime/panic.c:189 #5 0x00000200005c01d4 in runtime_mallocgc (size=40, typ=0, flag=0) at /home/uros/gcc-svn/trunk/libgo/runtime/malloc.goc:116 #6 0x00000200005a4b30 in __go_new (size=2199032605516) at /home/uros/gcc-svn/trunk/libgo/runtime/go-new.c:15 #7 0x00000200008e9a34 in regexp_syntax.inst.pN22_regexp_syntax.compiler (c=0x200009372f0, op=19 '\023') at /home/uros/gcc-svn/trunk/libgo/go/regexp/syntax/compile.go:173 #8 0x00000200008eaadc in regexp_syntax.rune.pN22_regexp_syntax.compiler (c=0x200009372f0, r=..., flags=212) at /home/uros/gcc-svn/trunk/libgo/go/regexp/syntax/compile.go:267 #9 0x00000200008eaf20 in regexp_syntax.compile.pN22_regexp_syntax.compiler (c=0xc208c1a988, re=0xc208b7fce0) at /home/uros/gcc-svn/trunk/libgo/go/regexp/syntax/compile.go:110 #10 0x00000200008eb628 in regexp_syntax.compile.pN22_regexp_syntax.compiler (c=0xc208c1a988, re=<optimized out>) at /home/uros/gcc-svn/trunk/libgo/go/regexp/syntax/compile.go:154 #11 0x00000200008eb2f0 in regexp_syntax.compile.pN22_regexp_syntax.compiler (c=0xc208c1a988, re=0xc208bb0f50) at /home/uros/gcc-svn/trunk/libgo/go/regexp/syntax/compile.go:146 #12 0x00000200008eb444 in regexp_syntax.compile.pN22_regexp_syntax.compiler (c=0xc208c1a988, re=<optimized out>) at /home/uros/gcc-svn/trunk/libgo/go/regexp/syntax/compile.go:156 #13 0x00000200008eb2f0 in regexp_syntax.compile.pN22_regexp_syntax.compiler (c=0xc208c1a988, re=0xc208bb1030) at /home/uros/gcc-svn/trunk/libgo/go/regexp/syntax/compile.go:146 #14 0x00000200008eb444 in regexp_syntax.compile.pN22_regexp_syntax.compiler (c=0xc208c1a988, re=<optimized out>) at /home/uros/gcc-svn/trunk/libgo/go/regexp/syntax/compile.go:156 #15 0x00000200008eb2f0 in regexp_syntax.compile.pN22_regexp_syntax.compiler (c=0xc208c1a988, re=0xc208bb1110) at /home/uros/gcc-svn/trunk/libgo/go/regexp/syntax/compile.go:146 ... #3822 0x00000200008eb444 in regexp_syntax.compile.pN22_regexp_syntax.compiler (c=0xc208c1a988, re=<optimized out>) at /home/uros/gcc-svn/trunk/libgo/go/regexp/syntax/compile.go:156 #3823 0x00000200008eb2f0 in regexp_syntax.compile.pN22_regexp_syntax.compiler (c=0xc208c1a988, re=0xc208c2d650) at /home/uros/gcc-svn/trunk/libgo/go/regexp/syntax/compile.go:146 #3824 0x00000200008eb444 in regexp_syntax.compile.pN22_regexp_syntax.compiler (c=0xc208c1a988, re=<optimized out>) at /home/uros/gcc-svn/trunk/libgo/go/regexp/syntax/compile.go:156 #3825 0x00000200008eb444 in regexp_syntax.compile.pN22_regexp_syntax.compiler (c=0xc208c1a988, re=<optimized out>) at /home/uros/gcc-svn/trunk/libgo/go/regexp/syntax/compile.go:156 #3826 0x00000200008eb700 in regexp_syntax.Compile (re=0xc208c2d6c0) at /home/uros/gcc-svn/trunk/libgo/go/regexp/syntax/compile.go:83 #3827 0x0000000120021584 in regexp.compile (expr=..., mode=<optimized out>, longest=<optimized out>) at regexp.go:161 #3828 0x00000001200213dc in regexp.Compile (expr=...) at regexp.go:118 #3829 0x0000000120021f18 in regexp.MustCompile (str=...) at regexp.go:219 #3830 0x000000012000fa14 in regexp.TestOnePassCutoff (t=<optimized out>) at all_test.go:478 #3831 0x00000200006a96ac in testing.tRunner (test=0xc20844f288, param=<optimized out>) at /home/uros/gcc-svn/trunk/libgo/go/testing/testing.go:422 #3832 testing.$thunk15 (__go_thunk_parameter=<optimized out>) at /home/uros/gcc-svn/trunk/libgo/go/testing/testing.go:504 #3833 0x00000200005b774c in kickoff () at /home/uros/gcc-svn/trunk/libgo/runtime/proc.c:229 #3834 0x0000020000e42264 in ?? () from /lib/libc.so.6.1 There is quite some recursion, maybe this is the reason for a deadlock.