[PATCH][C++] Improve PR15855 (compile-time/memory hog)

[Daniel Berlin]

On Fri, 23 Sep 2005, Jeffrey A Law wrote:

> On Fri, 2005-09-23 at 11:33 -0700, Mark Mitchell wrote:
>> Richard Guenther wrote:
>>
>>> After some sleep and coffee I re-structured the thing even a little
>>> more and came up with the following patch, which looks reasonably
>>> easy to follow.
>>
>> This version is OK for mainline.  After it's baked in for a week or so,
>> and assuming the 4.0.2 release has gone out, please apply it to the 4.0
>> branch for 4.0.3 as well.
> Cool.
>
> Now if someone wants to make another huge improvement to 15855, they
> should probably look at how we're handling SFTs and how they're
> exploding in the incremental SSA updates -- there's something like
> 5 million mappings for SFTs for one of the incremental SSA updates.
> We may have algorithmic issues with that many mappings and we may
> be doing some stupid stuff in creating that many to begin with.

We don't create SFT's for structures with more than x (where x 
is defaulting to 5) unless they are direct uses (ie not through pointers, 
or anything like that).

I sincerely doubt we actually have 5 million SFT's.  I'd be *incredibly* 
surprised.

:)