[all-commits] [llvm/llvm-project] 18fda8: [RISCV] Optimize scalable frame offset calculation...

[Philip Reames via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 18fda867f4777adbcb3ebfeaaeadeb46fc8c3157
      https://github.com/llvm/llvm-project/commit/18fda867f4777adbcb3ebfeaaeadeb46fc8c3157
  Author: Philip Reames <preames at rivosinc.com>
  Date:   2022-11-18 (Fri, 18 Nov 2022)

  Changed paths:
    M llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
    M llvm/test/CodeGen/RISCV/rvv/rv64-spill-vector-csr.ll

  Log Message:
  -----------
  [RISCV] Optimize scalable frame offset calculation when VLEN is precisely known

When we have a precisely known VLEN, we can replace runtime usage of VLENB with compile time constants. This converts offsets involving both fixed and scalable components into fixed offsets. The result is that we avoid the csr read of vlenb, and can often fold the multiply as well.

Differential Revision: https://reviews.llvm.org/D137591