[all-commits] [llvm/llvm-project] 78c1dc: [RISCV] Add a test showing incorrect VSETVLI inser...

[Fraser Cormack via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 78c1dcbf1bb989d97204c8637b6caee99bd97bca
      https://github.com/llvm/llvm-project/commit/78c1dcbf1bb989d97204c8637b6caee99bd97bca
  Author: Fraser Cormack <fraser at codeplay.com>
  Date:   2022-05-04 (Wed, 04 May 2022)

  Changed paths:
    M llvm/test/CodeGen/RISCV/rvv/vsetvli-insert-crossbb.mir

  Log Message:
  -----------
  [RISCV] Add a test showing incorrect VSETVLI insertion

This test shows incorrect cross-bb insertion. We'd expect to see
a SEW=8 vsetvli, something like:

        vsetvli zero, zero, e8, mf8, ta, mu
        vluxei64.v      v1, (a2), v8, v0.t

But instead the vsetvli is omitted and instead an inherited SEW=64
vsetvli is used:
        vmv1r.v v9, v1
        vsetvli a3, zero, e64, m1, ta, mu
        vmseq.vi        v9, v1, 0
        vmv1r.v v8, v0
        vmandn.mm       v0, v9, v2
        beqz    a0, .LBB0_2
    # %bb.1:
        vluxei64.v      v1, (a2), v8, v0.t
        vmv1r.v v3, v1

The "mask reg op" vmandn.mm in bb.1 appears to be confusing the insertion
process, as it is able to elide its own vsetvli as its VLMAX (SEW=8,
LMUL=MF8) is identical to the previous one (SEW=64, LMUL=1).

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D124089