[PATCH 1/8] Document signaling for min, max and ltgt operations

[Segher Boessenkool]

On Tue, Aug 20, 2019 at 06:13:00PM +0200, Ilya Leoshkevich wrote:
> > Am 20.08.2019 um 17:50 schrieb Segher Boessenkool <segher@kernel.crashing.org>:
> > There is currently no way to say (in trees or gimple or rtl) whether
> > comparisons are signaling ("ordered", generate a trap on an unordered
> > result).  I am working on this, but :-)
> 
> Isn't there?  This whole series is based on the following assumption:
> LT, LE, GT, GE are definitely signaling; LTGT is most likely signaling
> as well; the rest are not signaling.  This is based on gccint 11.6.3:
> Unary and Binary Expressions.

There is currently no way to implement, say, iseqsig.  And whether an
operation is signaling should be determined by the language frontend,
not separately by each backend!

(There should be a signaling and a non-signaling version of every float
comparison that can be unordered).


Segher