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Re: GCSE store motion


Roger,

	There is no argument that GCSE store motion and store merging can
be useful.  The only question is whether the current implementation is
effective.

	We all concede that the current GCSE store-motion implementation
does have an effect on a store in your example from glibc.  We are asking
that GCSE store motion show demonstrable improvement in macroscopic
performance of code produced by GCC.

	Maybe we should rearrange the disabling so that toplev.c defaults
flag_gcse_sm to 0 instead of disabling the optimization in gcse.c itself.
Then this file in glibc could be compiled with -fgcse-sm in the one
instance it has been shown to be useful.

	When store motion shows performance improvement across a wider
range of applications, then we can enable that optimization by default.

David


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