-O1 single optimization parameter

[Andrew Haley]

massimiliano cialdi wrote:
> I use gcc 4.2.2 and I tried both -O0 and -O1.
> If I use -O1 I can see that use of stack is better.
> In gcc manual (http://gcc.gnu.org/onlinedocs/gcc-4.2.4/gcc/Optimize-Options.html#Optimize-Options)
> is reported that -O1 activate
> -fdefer-pop
> -fdelayed-branch
> -fguess-branch-probability
> -fcprop-registers
> -fif-conversion
> -fif-conversion2
> -ftree-ccp
> -ftree-dce
> -ftree-dominator-opts
> -ftree-dse
> -ftree-ter
> -ftree-lrs
> -ftree-sra
> -ftree-copyrename
> -ftree-fre
> -ftree-ch
> -funit-at-a-time
> -fmerge-constants
> 
> so in gcc command line I have replaced -O1 with all these parameters,
> but I obtain a larger binary and a worst stack usage. Is the same
> thing of -O0.

Right.

> How can I reproduce -O1 behaviour using simple command line parameter?

You can't have optimization without -O.

Andrew.