Re: GCC still getting a lot slower

[Nathanael Nerode <neroden at twcny dot rr dot com>]

Paul Jarc said:
>Nathanael Nerode <neroden@twcny.rr.com> wrote:
>> Frankly, I don't think we should look at bootstrap time.  A number of
>> the largest changes in B-I-B were necessary build process changes,  which
>> are quite likely to slow down the build *of* the compiler, but not the
>> performance of the compiler.  Or, in other words, "so what?". ;-)
>
>As someone else noted a while ago, bootstrap times are important
>because changes are tested by bootstrapping.  So slow bootstraps slow
>down all other progress.
Yeah.  But when I said 'necessary', I meant it; these changes have been 
on the TODO list forever, and they're correctness issues.

>> Can we test compile time change of some *fixed* piece of code, 
>>perhaps?
>
>That would also be useful, in its own way.

If on the other hand the bootstrap slowdown is due to changes in the way 
the compiler works -- which would be evidenced by compile time change in 
a fixed piece of code -- then it's likely to be a bad change which we 
*can* track down and fix by binary search on the b-i-b branch.  The 
changes made in this regard on B-I-B were fewer, smaller, and less invasive.

For instance, the change to every single C file on the tree was a 
build-process change which shouldn't have affected compiler behavior.
(If it did, that's another matter.)

--Nathanael