Re: [GCC 3.0] Bad regression, binary size

[Daniel Berlin <dan at cgsoftware dot com>]

Phil Edwards <pedwards@disaster.jaj.com> writes:

> On Mon, Jul 09, 2001 at 02:54:21PM -0700, Justin Guyett wrote:
>> I dunno about the 1minute+ helloworld compile time someone just suggested,
>> but this is disturbing:
>> (v2.95) g++ -o hello hello.cc  0.15s user 0.03s system 96% cpu 0.186 total
>> (v3.0)  g++ -o hello hello.cc  2.04s user 0.06s system 99% cpu 2.102 total
>> 
>> if there's a 2 second loading overhead for g++v3, that's 2 seconds * (#
>> files) which can be quite a lot in large trees.  Is this simply from
>> linking in the new libstdc++?
> 
> Parsing the libstdc++ headers takes time, mostly because nearly all the
> code is in the headers.  Once we have 'export' this should be
> better.

This isn't the trouble, it's the inlining.
We expand something from 300 insns to 15k insns, which itself takes
time, memory, and then the backend has to deal with a lot more.

Parsing took < 5 seconds on my example.
It was the rest of compilation that took > 30 seconds.
Without inlining, it took 5 seconds at -O3 total.
There must be a happy medium.

 
> 
> Phil
> 
> -- 
> Would I had phrases that are not known, utterances that are strange, in
> new language that has not been used, free from repetition, not an utterance
> which has grown stale, which men of old have spoken.
>                                      - anonymous Egyptian scribe, c.1700 BC

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