Re: [PATCH/RFC] Reduce call chain length in netfilter

[Patrick McHardy <kaber@xxxxxxxxx>]

David S. Miller wrote:

> In the generated asm on sparc64, invoke2() gets a tail-call
> whereas invoke() does not.  Hmmm...
Apparently support for indirect tail-calls was added to gcc 3.4.

gcc-3.3.5:
0x0000000000000000 <invoke+0>:  sub    $0x8,%rsp
0x0000000000000004 <invoke+4>:  callq  *%esi
0x0000000000000006 <invoke+6>:  add    $0x8,%rsp
0x000000000000000a <invoke+10>: retq  

gcc-3.4.4:
0x0000000000000000 <invoke+0>:  mov    %rsi,%r11
0x0000000000000003 <invoke+3>:  jmpq   *%r11d

Regards
Patrick