Re: C++ compile-time regressions (was: GCC 3.0.1 Status Report)

[Gabriel Dos Reis <gdr at codesourcery dot com>]

Joe Buck <jbuck@synopsys.com> writes:

| > Joe Buck <jbuck@synopsys.COM> writes:
| > 
| > | > I'm rather sure, though, that g++ is not generating efficient code for
| > | > complicated, nested STL and STL-like structures in the presence of
| > | > libstdc++-v3 (iterators are now classes instead of pointers).
| > | 
| > | But the classes have one member, so we should still be getting equivalent
| > | code, provided that we get ADDRESSOF working as well as it did in 2.95.x.
| > 
| > Now that we have a branch for doing tree-based optimization, what do
| > you think about trying to implement "scalar replacement of aggregates"
| > optimization and see how good we can do with STL-like structures?
| 
| Yes!  This is very important, not just for STL-like structures, but for
| proxy objects (e.g. references to bits in a packed bit vector class).

Yes, I have similar concern with "small" classes like color, point,
vector classes in my personal scientific visualization applications.

| You'll find some good test cases in Boost, particularly the Boost Graph
| Library; our current compilers (2.95.x or 3.0.x) do poorly because many
| of the iterators and function results are classes with more than one data
| member.

Thanks.

-- Gaby
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