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Re: [PATCH] Fix PR26898, 2nd try
On Fri, 31 Mar 2006, Richard Guenther wrote:
> On 3/31/06, Joseph S. Myers <joseph@codesourcery.com> wrote:
> > I take it that at this point in folding it is guaranteed that the
> > constants are non-negative, i.e. you don't have to deal with "X + -1" or
> > "X - -1"?
>
> Hmm I thought they were canonicalized - but now I verified they are not.
> *sigh* Are there any problems with treating X - -1 as X + 1?
No, though you can't fold X + INT_MIN or X - INT_MIN that way. (But
the optimization is still valid as applied to X + INT_MIN CMP Y - INT_MAX
converted to X - 1 CMP Y.)
--
Joseph S. Myers http://www.srcf.ucam.org/~jsm28/gcc/
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