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Re: GCSE store motion



> I am completely for disabling optimizations on the mainline that do
> nothing but waste time in their current state (though even a 1%
> improvement might be arguably worth it).

Hi Dan,

You'll also be aware of the "Store merging" section of the "Optimizer
inadequecies" page, http://gcc.gnu.org/projects/optimize.html#storemerge
Although store motion isn't particularly functional at the moment, it
provides a framework for further GCC improvements in the future.

I'd agree that perhaps is should be in -fexpensive-optimizations, but
I'm not convinced that its broken.  As you point out in your commentary
of its deficiencies, it pessimizes const/pure functions etc..., but
these don't affect the correctness of the code, just decrease the number
of places this optimization is applicable.

Roger
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