[all-commits] [llvm/llvm-project] 860c62: [RISCV] Refine known bits for READ_VLENB

[Philip Reames via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 860c62f53cb245a8c93725cc45de54a8a3f92f25
      https://github.com/llvm/llvm-project/commit/860c62f53cb245a8c93725cc45de54a8a3f92f25
  Author: Philip Reames <preames at rivosinc.com>
  Date:   2022-06-28 (Tue, 28 Jun 2022)

  Changed paths:
    M llvm/lib/Target/RISCV/RISCVISelLowering.cpp
    M llvm/test/CodeGen/RISCV/rvv/rvv-vscale.i64.ll

  Log Message:
  -----------
  [RISCV] Refine known bits for READ_VLENB

This implements known bits for READ_VALUE using any information known about minimum and maximum VLEN. There's an additional assumption that VLEN is a power of two.

The motivation here is mostly to remove the last use of getMinVLen, but while I was here, I decided to also fix the bug for VLEN < 128 and handle max from command line generically too.

Differential Revision: https://reviews.llvm.org/D128758