[PATCH] Document a bunch of expression tree codes

[Richard Henderson]

On Tue, May 25, 2004 at 09:03:23PM -0600, Roger Sayle wrote:
> 	NOT_EXPR (UNORDERED_EXPR (x, y)) => ORDERED_EXPR (x, y)
> 	NOT_EXPR (ORDERED_EXPR (x, y)) => UNORDERED_EXPR (x, y)

Yes, we already do this at the rtl level.

> 	UNORDERED (x, x) => isnan (x)
> 	ORDERED (x, x) => NOT_EXPR (isnan (x))

Definitely the other way around.

> And if -fno-trapping-math,
> 
> 	NOT_EXPR (UNLT_EXPR (x, y)) => GE_EXPR (x, y)

Also done at rtl level.

> And if -fno-trapping-math and HONOR_NANS (mode),
> 
> 	NOT_EXPR (GE_EXPR (x, y)) => UNLT_EXPR (x, y)

Sure.


r~