[PATCH] D76491: [ARM,MVE] Add ACLE intrinsics for the vaddv/vaddlv family.

[Simon Tatham via Phabricator via cfe-commits]

simon_tatham created this revision.
simon_tatham added reviewers: dmgreen, MarkMurrayARM, miyuki, ostannard.
Herald added subscribers: cfe-commits, danielkiss, hiraditya, kristof.beyls.
Herald added a project: clang.

I've implemented them as target-specific IR intrinsics rather than
using `@llvm.experimental.vector.reduce.add`, on the grounds that the
'experimental' intrinsic doesn't currently have much code generation
benefit, and my replacements encapsulate the sign- or zero-extension
so that you don't expose the illegal MVE vector type (`<4 x i64>`) in
IR.

The machine instructions come in two versions: with and without an
input accumulator. My new IR intrinsics, like the 'experimental' one,
don't take an accumulator parameter: we represent that by just adding
on the input value using an ordinary i32 or i64 add. So if you write
the `vaddvaq` C-language intrinsic with an input accumulator of zero,
it can be optimised to VADDV, and conversely, if you write something
like `x += vaddvq(y)` then that can be combined into VADDVA.

Most of this is achieved in isel lowering, by converting these IR
intrinsics into the existing `ARMISD::VADDV` family of custom SDNode
types. For the difficult case (64-bit accumulators), isel lowering
already implements the optimization of folding an addition into a
VADDLV to make a VADDLVA; so once we've made a VADDLV, our job is
already done, except that I had to introduce a parallel set of ARMISD
nodes for the //predicated// forms of VADDLV.

For the simpler VADDV, we handle the predicated form by just leaving
the IR intrinsic alone and matching it in an ordinary dag pattern.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D76491

Files:
  clang/include/clang/Basic/arm_mve.td
  clang/test/CodeGen/arm-mve-intrinsics/vaddv.c
  llvm/include/llvm/IR/IntrinsicsARM.td
  llvm/lib/Target/ARM/ARMISelLowering.cpp
  llvm/lib/Target/ARM/ARMISelLowering.h
  llvm/lib/Target/ARM/ARMInstrMVE.td
  llvm/test/CodeGen/Thumb2/mve-intrinsics/vaddv.ll

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