[all-commits] [llvm/llvm-project] a33f60: [RISCV] Add test case showing suboptimal BUILD_VEC...

[Fraser Cormack via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: a33f60db39836d94a79557b147515d42d30ecba3
      https://github.com/llvm/llvm-project/commit/a33f60db39836d94a79557b147515d42d30ecba3
  Author: Fraser Cormack <fraser at codeplay.com>
  Date:   2021-07-29 (Thu, 29 Jul 2021)

  Changed paths:
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-fp-buildvec.ll

  Log Message:
  -----------
  [RISCV] Add test case showing suboptimal BUILD_VECTOR lowering

The second test case added here was pointed out to me by @craig.topper
and shows how we "optimize" a two-element BUILD_VECTOR from being one
load from the constant pool to two loads from the constant pool.

The first test case shows that since materialization for the
floating-point +0.0 value is cheap and doesn't involve a load, the
optimization is more clearly beneficial here.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D106962