Given a floating point store from an extracted vector, with an integer
VGETLANE that already exists, storing the existing VGETLANEu directly
can be better for performance. As the value is known to already be in an
integer registers, this can help reduce fp register pressure, removed
the need for the fp extract and allows use of more integer post-inc
stores not available with vstr.
This can be a bit narrow in scope, but helps with certain biquad kernels
that store shuffled vector elements.
Differential Revision: https://reviews.llvm.org/D96159
Because we mark all operations as expand for v2f64, scalar_to_vector
would end up lowering through a stack store/reload. But it is pretty
simple to implement, only inserting a D reg into an undef vector. This
helps clear up some inefficient codegen from soft calling conventions.
Differential Revision: https://reviews.llvm.org/D96153
David Green