[LLVMdev] [MC] Removing relaxation control

[Chris Lattner]

On Feb 25, 2011, at 11:38 AM, Rafael Avila de Espindola wrote:

>>> Can someone else try to reproduce this?
> 
> I tried gcc.c from 
> http://people.csail.mit.edu/smcc/projects/single-file-programs/ and the 
> difference is a bit more noticeable:
> 
> -O0 -mno-relax-all
> 
> real	0m13.182s
> user	0m12.690s
> sys	0m0.450s
> 
> -O0
> 
> gcc.o is 10932968 bytes.
> 
> real	0m12.969s
> user	0m12.520s
> sys	0m0.410s
> 
> gcc.o is 11410552 bytes
> 
> IMHO it would still be reasonable to switch to no-relax-all, but I am 
> probably not the best one to make the call.

That looks like a 1.5% speedup in realtime and 10% speedup in system time (though I'm not sure I believe that).  I think it should stay on for -O0 for C files.  Turning it off at -O0 for .s files makes perfect sense to me though.

-Chris