[all-commits] [llvm/llvm-project] 9c4108: [RISCV] Legalize fixed length (insert_subvector un...

[Craig Topper via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 9c410838d2bcaa087e867e9f8a353fe455588287
      https://github.com/llvm/llvm-project/commit/9c410838d2bcaa087e867e9f8a353fe455588287
  Author: Craig Topper <craig.topper at sifive.com>
  Date:   2022-01-17 (Mon, 17 Jan 2022)

  Changed paths:
    M llvm/lib/Target/RISCV/RISCVISelLowering.cpp
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-extload-truncstore.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-fp-conv.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-fp2i.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-i2fp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-insert-subvector.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-insert.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-int-exttrunc.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-masked-gather.ll

  Log Message:
  -----------
  [RISCV] Legalize fixed length (insert_subvector undef, X, 0) to a scalable insert.

We were considering this legal, but later the undef would become an all
zeros vector. This would cause us to need to re-legalize the insert later
into a vslideup with zero vector.

This patch catches the case and directly legalizes it to a scalable
insert.

Reviewed By: frasercrmck

Differential Revision: https://reviews.llvm.org/D117377