compile time regressions (was: merging for 3.4)

[Mike Stump]

On Tuesday, December 10, 2002, at 02:23 PM, Neil Booth wrote:
>> No, no, you have it backwards...  PCH is going to expose all that slow
>> code that should be fast, that has to be fast, so that we can fix it.
>> By being 12x faster, or just 2x faster, there is _much_ less room to 
>> be
>> slow, not more, really.
>
> But slow code in things that PCH elides won't get exposed by the very
> nature of PCH.  e.g. drastic CPP slowdowns (not gonna happen!), or say
> the parser.

This is called pch build time.  It is important, just not that 
important.  In a 10 minute compile, it might be 20 seconds.  Also, by 
having cycle counter times in -freport-time, and measuring pch build 
time, one can speed that up, arbitrarily fast, if one wants.

You'll notice however, that more time is wasted reconsidering in 
cxx_finish_file however.

:-)