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Re: A question about integer promotion in GCC


Joseph S. Myers wrote:
On Mon, 6 Sep 2004, Nathan Sidwell wrote:


IMO when to tackle this is after the next release branches, and the
way to do is implement fe-fold-constant-expr (tree, flags) first, and then
make a fold-const optimizer pass from the remnants.


That seems a plausible approach. (With the interface for folding true constants then getting adapted so it can pass overflow information back other than by TREE_OVERFLOW etc., with a view to removing those overflow
yay!

flags from constants.) Splitting fold that way, with the subsequent pass running just before gimplification, should be straightforward. (I don't
I'd suspect we don't want it to run once just there.  It should be cheap
enough to run multiple times on gimple form.

know what performance impact there might be, though gains from smaller footprint while parsing the whole file before optimising any of it are possible.) The hard bit would be creating a fold parse for GIMPLE that does everything fold currently does.
sure, but that's a goal that can be incrementally acheived.

nathan
--
Nathan Sidwell    ::   http://www.codesourcery.com   ::     CodeSourcery LLC
nathan@codesourcery.com    ::     http://www.planetfall.pwp.blueyonder.co.uk



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