Re: Question about JUMP and LINK

2012-03-19 Thread bill4carson


On 2012年03月16日 23:23, Dave Hylands wrote:
 Hi Bill,

 On Thu, Mar 15, 2012 at 11:52 PM, bill4carsonbill4car...@gmail.com  wrote:
 Hi, All

 The question is simple.

 func_a {

 call func_b
 }

 func_b {

 call func_c
 }

 func_c {

 return to func_a
 }


 The compiler I use let func_c to return func_a directly, IOW when func_b
 calls func_c, it use JUMP, other JUMP and LINK, and it's definitely not
 a question about inline or noinline.

 So can I ask why how to let the compiler use JUMP and LINK when func_b
 calls func_c?

 This is called Tail Optimization. See
 http://c2.com/cgi/wiki?TailCallOptimization

 gcc (I'm using 4.4.4) with -O3 does this.

Thanks for the information.


 If it's not the right place to post this, sorry for the noise.

 The kernel newbies list is probably not the right place (since this
 has nothing to do with the kernel). It also has nothing to do with
 binutils. It's a gcc optimization, so picking a gcc list would
 probably be more appropriate.


-- 
I am a slow learner
but I will keep trying to fight for my dreams!

--bill

___
Kernelnewbies mailing list
Kernelnewbies@kernelnewbies.org
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies


Question about JUMP and LINK

2012-03-16 Thread bill4carson
Hi, All

The question is simple.

func_a {

call func_b
}

func_b {

call func_c
}

func_c {

return to func_a
}


The compiler I use let func_c to return func_a directly, IOW when func_b
calls func_c, it use JUMP, other JUMP and LINK, and it's definitely not
a question about inline or noinline.

So can I ask why how to let the compiler use JUMP and LINK when func_b
calls func_c?

If it's not the right place to post this, sorry for the noise.

thanks

-- 
I am a slow learner
but I will keep trying to fight for my dreams!

--bill

___
Kernelnewbies mailing list
Kernelnewbies@kernelnewbies.org
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies