https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70841
Bug ID: 70841
Summary: reassoc fails to handle FP division
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: rguenth at gcc dot gnu.org
Target Milestone: ---
reassoc fails to handle
float foo (float x, float y)
{
return x * y / x;
}
with -freciprocal-math (at least) it could handle this as
x * y * (1/x)
and simplify ops accordingly (with -funsafe-math-opts or maybe already
with -ffp-contract=fast). Implementation-wise this could be
handled similar to how we handle minus for plus reassoc. OTOH
it would be better to rewrite that with a flag on the op "negate"
and division could be handled with a flag "invert".
