Revisiting the TYPE_IS_SIZETYPE issue

[Paolo Bonzini]

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