[AArch64] Optimize floating point materialization

This patch changes isFPImmLegal to return if the value can be enconded
as the immediate operand of a logical instruction besides checking if
for immediate field for fmov.

This optimizes some floating point materization, inclusive values
used on isinf lowering.

Reviewed By: rengolin, efriedma, evandro

Differential Revision: https://reviews.llvm.org/D57044


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@352866 91177308-0d34-0410-b5e6-96231b3b80d8
9 files changed