What makes a difference in the resulting compiler's speed when building gcc?

[Marc Glisse]

On Thu, 27 Oct 2016, Sven C. Dack wrote:

> I've been installing private copies of gcc for a while now, but only recently 
> did I notice that my distro's gcc (Debian testing) is doing much better when 
> comparing compile times than any of my copies. For instance does it take 230s 
> for my copy to compile a linux kernel, but only 163s for my distro's gcc, 
> which is almost a minute in difference for something that doesn't take more 
> than 3-4 minutes to compile.
>
> What makes this noteworthy for me is that I've compiled my copy with 
> profiledbootstrap and LTO enabled and also optimized it for my CPU, whereas 
> the distro's compiler won't have been optimized quite that much, but yet is 
> it so much faster in speed. I don't know how exactly my distro's gcc has been 
> set up, because the Debian build rules are rather complex and include their 
> own set of patches. So I thought I start with asking here first.
>
> What is that can make such a huge difference in compile speed for two copies 
> of gcc, both version 6.2, using the same options, on the same source? Or are 
> any of the configure options know to have a huge impact on the resulting 
> compiler's speed?

--enable-checking=release would be the first thing to check.

-- 
Marc Glisse