riscv64: use bitmanip extension, declare temp regs

This patch converts the VREG accessors to use
the denser SH2ADD from Zba, and converts some
common macros to declare their temporaries at
their call sites.

Test: Run these opcodes against all interpreter
tests on a Linux RISC-V VM.

(1) setup
  lunch aosp_riscv64-userdebug

  export ART_TEST_SSH_USER=ubuntu
  export ART_TEST_SSH_HOST=localhost
  export ART_TEST_SSH_PORT=10001
  export ART_TEST_ON_VM=true

  . art/tools/buildbot-utils.sh
  art/tools/buildbot-build.sh --target

  # Create, boot and configure the VM.
  art/tools/buildbot-vm.sh create
  art/tools/buildbot-vm.sh boot
  art/tools/buildbot-vm.sh setup-ssh  # password: 'ubuntu'

  art/tools/buildbot-cleanup-device.sh
  art/tools/buildbot-setup-device.sh
  art/tools/buildbot-sync.sh

(2) test
  art/test.py --target -r --no-prebuild --ndebug --64  -j 12 --cdex-none --interpreter

Bug: 283082047
Change-Id: Id37694761610b6a5bae54d6b244b4e75a4ea5a85
5 files changed