[all-commits] [llvm/llvm-project] 964c92: [RISCV][InsertVSETVLI] Eliminate the AVLIsIgnored ...

[Philip Reames via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 964c92d04f039a205327cb47c75919096f9fca94
      https://github.com/llvm/llvm-project/commit/964c92d04f039a205327cb47c75919096f9fca94
  Author: Philip Reames <preames at rivosinc.com>
  Date:   2024-06-17 (Mon, 17 Jun 2024)

  Changed paths:
    M llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-expandload-fp.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-expandload-int.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-llrint.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-lrint.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-masked-gather.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-masked-scatter.ll
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-unaligned.ll
    M llvm/test/CodeGen/RISCV/rvv/vsetvli-insert-crossbb.mir

  Log Message:
  -----------
  [RISCV][InsertVSETVLI] Eliminate the AVLIsIgnored state (#94658)

As noted in one of the existing comments, the job AVLIsIgnored was
filing was really more of a demanded field role. Since we recently
realized we can use the values of VL on MI even in the backwards pass,
let's exploit that to improve demanded fields, and delete AVLIsIgnored.

Note that the test change is a real regression, but only incidental to
this patch. The backwards pass doesn't have the information that the VL
following a VL-preserving vtype is non-zero. This is an existing
problem, this patch just adds a few more cases where we prove
vl-preserving is legal.



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