Re: Faster compilation speed

[Stan Shebs <shebs at apple dot com>]

Tim Josling wrote:

> This is consistent with my tests; I found that a simplistic allocation which
> put everything on the same page, but which never freed anything, actually
> bootstrapped GCC faster than the standard GC.
Not too surprising actually; GCC's own sources aren't the hard cases for GC.

> The GC was never supposed to make GCC faster, it was supposed to reduce
> workload by getting rid of memory problems. But I doubt it achieves that
> objective. Certainly, keeping track of all the attempts to 'fix' GC has burned
> a lot of my time.
The original rationale that I remember was to deal with hairy C++ code
where the compiler would literally exhaust available VM when doing
function-at-a-time compilation.  If that's still the case, then memory
reclamation is a correctness issue.  But it's worth tinkering with the
heuristics; we got a little improvement on Darwin by bumping
GGC_MIN_EXPAND_FOR_GC from 1.3 to 2.0 (it was a while back, don't
have the comparative numbers).

Stan