GNU C++ 4.0.1/4.1.0 cache misses on MICO sources.

[Karel Gardas]

On Mon, 23 May 2005, Mark Mitchell wrote:

> Mike Stump wrote:
>> On May 17, 2005, at 3:16 PM, Karel Gardas wrote:
>> 
>>> 1) the most expensive seems to be comptypes -- at least from data L2
>>>    refill point of view (~17%)
>>> 
>>> 2) comptypes is also the most CPU intensive operation since the most
>>>    of time is spent there
>> 
>> 
>> I think comptypes can be sped up by canonicalizing types better, and  also 
>> adding a conservative hash and checking it first.
>
> We've researched this in detail.
>
> Speeding up comptypes can best be done by calling it less often.  One of the 
> primary uses is the template machinery, which works very hard to work out 
> whether it already has an existing specialization.  The first step is to 
> insert canonicalizations and other speedups there; that would reduce the 
> number of calls to comptypes dramatically.  There are also places in the 
> front end that make redundant calls to comptypes; for example, during 
> declaration processing we sometimes check whether or not two declarations 
> match more than once.
>
> The changes you suggest might still be helpful, but I'd prefer to see the 
> bigger algorithms fixed first, as those changes will have secondary benefits 
> beyond comptypes as well.

Mark,

shall I put some RFE to bugzilla to have it recordered somewhere, or is 
this already on your company or team TODO list?

Thanks!
Karel
--
Karel Gardas                  kgardas@objectsecurity.com
ObjectSecurity Ltd.           http://www.objectsecurity.com