hg: panama/dev: Some fine-tunes for AArch64 reduce_add operations

[yang.zhang at arm.com]

Changeset: 4f41d86e85af
Author:    yzhang
Date:      2019-11-21 15:32 +0800
URL:       https://hg.openjdk.java.net/panama/dev/rev/4f41d86e85af

Some fine-tunes for AArch64 reduce_add operations
As reduce_add operation can be applied to signed values, we should use
sign-extension when possible. And using addp/faddp instead of add/fadd can
reduce one instruction.

Contributed-by: qi.feng at arm.com

! src/hotspot/cpu/aarch64/aarch64.ad
! src/hotspot/cpu/aarch64/assembler_aarch64.hpp