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Re: 100x perfomance regression between gcc 3.4.5 and gcc 4.X


On 3/13/06, tbp <tbptbp@gmail.com> wrote:
> On 3/13/06, Paolo Bonzini <paolo.bonzini@lu.unisi.ch> wrote:
> >Wait wait.  PR/21195 is about inlining
> > the SSE builtins.
> No. PR/21195 was really about inline heuristic going ballistic.
> Those intrinsics are thin wrappers around builtins, and ultimately
> resolve to a couple of operations. Typical C++ (accessors/ctors) also
> presents lots of such small functions.
> And guess what, same cause same symptom.

Starting with gcc 4.1.0 we have inline heuristics in place that will _always_
inline such simple "wrappers".  So, if this still happens, there is a bug in the
heuristics and that should be reported.  Before 4.1.0 the heuristics were bogus
and wrappers were not inlined all the time.

So, can you verify you are happy with the heuristics in 4.1.0 (not talking about
inlining of memcpy/memset that are really not function inlining, but
the SSE/altivec
inline function implementations).

Richard.


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