riscv_fmv_rv128

Fix: Remove RV128-only fmv instructions

• Status: Merged for 2.39
• Branch: riscv-remove-fmv-rv128
• Tracking PR: none
• Mailing List:
  • PATCH v1 (2022-05-20)

Issue Fixed

There are two RV128-only instructions enabled on RV64!

1. fmv.x.q
2. fmv.q.x

Those instructions will be RV128-only instructions that transfer 128-bit floating point values between a GPR and a FPR. As RV64 only has 64-bit general purpose registers, they should not be valid (64-bit transfer instructions, fmv.x.d and fmv.d.x are, on the other hand, valid).

This patchset is simple. It just removes those instructions and makes sure that they are invalid on RV64.