[all-commits] [llvm/llvm-project] d23de1: [RISCV] Add tests for concats of vectors that coul...

[Luke Lau via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: d23de1bd155bc9ab972dd19ed8c5a27b42bac5da
      https://github.com/llvm/llvm-project/commit/d23de1bd155bc9ab972dd19ed8c5a27b42bac5da
  Author: Luke Lau <luke at igalia.com>
  Date:   2023-04-19 (Wed, 19 Apr 2023)

  Changed paths:
    A llvm/test/CodeGen/RISCV/rvv/fixed-vectors-strided-load-combine.ll

  Log Message:
  -----------
  [RISCV] Add tests for concats of vectors that could become strided loads

These patterns of concat_vector nodes of loads can be combined into
widened vector loads or a strided vector loads.

Co-authored-by: Philip Reames <preames at rivosinc.com>

Differential Revision: https://reviews.llvm.org/D147712


  Commit: 18dc205112dfc411546272e3eb378088944620eb
      https://github.com/llvm/llvm-project/commit/18dc205112dfc411546272e3eb378088944620eb
  Author: Luke Lau <luke at igalia.com>
  Date:   2023-04-19 (Wed, 19 Apr 2023)

  Changed paths:
    M llvm/lib/Target/RISCV/RISCVISelLowering.cpp
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-strided-load-combine.ll

  Log Message:
  -----------
  [RISCV] Combine concat_vectors of loads into strided loads

If we're concatenating several smaller loads separated by a stride, we
can try and increase the element size and perform a strided load.
For example:

```
concat_vectors (load v4i8, p+0), (load v4i8, p+n), (load v4i8, p+n*2), (load v4i8, p+n*3)
=>
vlse32 p, stride=n, VL=4
```

This pattern can be produced by the SLP vectorizer.

A special case is when the stride is exactly equal to the width of the
vector, in which case it can be converted into a single consecutive
vector load. For example:

```
concat_vectors (load v4i8, p), (load v4i8, p+4), (load v4i8, p+8), (load v4i8, p+12)
=>
vle8 p, VL=16
```

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D147713


Compare: https://github.com/llvm/llvm-project/compare/107b307bd61e...18dc205112df