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Re: Revisiting the TYPE_IS_SIZETYPE issue

Richard Guenther wrote:
On Mon, May 26, 2008 at 12:23 PM, Paolo Bonzini <bonzini@gnu.org> wrote: 
So my idea (I have this for some time now, but there's always lack
of time to implement it ...) is to make the existing tree codes
'may overflow' operations and introduce new tree code variants
with the 'does not overflow' semantics.  This way we conservatively
preserve 'may overflow' in legacy code.

That seems extremely ugly, especially to make fold-const.c aware of that.
 It would be better to make the "overflow definition" a flag for a single
PLUS_EXPR node (or PLUS rtl).


That obviously doesn't work.  As fold operates on "destructed" trees
you have no way of placing the flag somewhere.

I'm definitely rusty. I guess modifying fold to add an argument does not make sense, but changing all x == PLUS_EXPR to PLUS_EXPR_P (x) is also a nightmare.

Paolo

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