Valgrind crashes with the following report: 
vex x86->IR: unhandled instruction bytes: 0xFF 0x69 0x38 0x90
==24487== valgrind: Unrecognised instruction at address 0x8059713.
==24487== Your program just tried to execute an instruction that Valgrind
...

The code looks like this: 
080596f8 <NaClSwitch>:
 80596f8:       58                      pop    %eax
 80596f9:       31 c9                   xor    %ecx,%ecx
 80596fb:       59                      pop    %ecx
 80596fc:       8b 51 30                mov    0x30(%ecx),%edx
 80596ff:       8b 69 14                mov    0x14(%ecx),%ebp
 8059702:       8b 79 08                mov    0x8(%ecx),%edi
 8059705:       8b 71 04                mov    0x4(%ecx),%esi
 8059708:       8b 19                   mov    (%ecx),%ebx
 805970a:       8e 69 2e                mov    0x2e(%ecx),%gs
 805970d:       8e 61 2c                mov    0x2c(%ecx),%fs
 8059710:       8e 41 2a                mov    0x2a(%ecx),%es
 8059713:       ff 69 38                ljmp   *0x38(%ecx)        <<<<<<<<<<<<<<<<<<<<<<
 8059716:       90                      nop
 8059717:       90                      nop