On Thu, 20 Aug 2015, Hurugalawadi, Naveen wrote:
The following testcase does not generate "x" as needed.
====================
double t (double x)
{
x = sqrt (x) * sqrt (x);
return x;
}
====================
With -fno-math-errno, we CSE the calls to sqrt, so I would expect this to
match:
(mult (SQRT@1 @0) @1)
Without the flag, I expect that one will apply
(simplify
(mult (SQRT:s @0) (SQRT:s @1))
(SQRT (mult @0 @1)))
and then maybe we have something converting sqrt(x*x) to abs(x) or maybe
not.
I wonder if all the unsafe math optimizations are really ok without
-fno-math-errno...
--
Marc Glisse
