Comment # 9 on bug 1048861 from Richard Biener

(In reply to Jon Brightwell from comment #8)
> I maybe reading it wrong but rsi isn't 16b aligned
> 
>    ���0x7ffff785b360 <__strcmp_ssse3>         mov    %esi,%ecx                
> 
>    ���0x7ffff785b362 <__strcmp_ssse3+2>       mov    %edi,%eax                
> 
>    ���0x7ffff785b364 <__strcmp_ssse3+4>       and    $0x3f,%rcx               
> 
>    ���0x7ffff785b368 <__strcmp_ssse3+8>       and    $0x3f,%rax               
> 
>    ���0x7ffff785b36c <__strcmp_ssse3+12>      cmp    $0x30,%ecx               
> 
>    ���0x7ffff785b36f <__strcmp_ssse3+15>      ja     0x7ffff785b3b0
> <__strcmp_ssse3+80>                                                         
> 
>    ���0x7ffff785b371 <__strcmp_ssse3+17>      cmp    $0x30,%eax               
> 
>    ���0x7ffff785b374 <__strcmp_ssse3+20>      ja     0x7ffff785b3b0
> <__strcmp_ssse3+80>                                                         
> 
> b+>���0x7ffff785b376 <__strcmp_ssse3+22>      movlpd (%rdi),%xmm1             
> 
>    ���0x7ffff785b37a <__strcmp_ssse3+26>      movlpd (%rsi),%xmm2             
> 
>    ���0x7ffff785b37e <__strcmp_ssse3+30>      movhpd 0x8(%rdi),%xmm1          
> 
>    ���0x7ffff785b383 <__strcmp_ssse3+35>      movhpd 0x8(%rsi),%xmm2          
> 
>    ���0x7ffff785b388 <__strcmp_ssse3+40>      pxor   %xmm0,%xmm0
> 
> rax            0x0      0
> rbx            0x7fffffffb5d0   140737488336336
> rcx            0x0      0
> rdx            0x7fffffffb46c   140737488335980
> rsi            0x555556c12b40   93825016081216
> rdi            0x0      0
> rbp            0x7fffffffb46c   0x7fffffffb46c
> rsp            0x7fffffffb458   0x7fffffffb458
> r8             0x5555569b0550   93825013581136
> r9             0x7fffec1e12b8   140737154781880
> r10            0x848    2120
> r11            0x7ffff785b360   140737346122592
> r12            0x7fffbe81ddc0   140736389569984
> r13            0x0      0
> r14            0xffffffff       4294967295
> r15            0x7fffffffb668   140737488336488
> rip            0x7ffff785b376   0x7ffff785b376 <__strcmp_ssse3+22>
> eflags         0x10283  [ CF SF IF RF ]
> cs             0x33     51
> ss             0x2b     43
> ds             0x0      0
> es             0x0      0
> fs             0x0      0
> gs             0x0      0

rdi is 0 so this is a NULL pointer dereference rather than an alignment issue.
Something does strcmp (..., NULL).