[Mlir-commits] [mlir] [mlir][ArmNeon] Add pack/mmt4d path to f32 linalg.matmul integration test (PR #225063)

[Federico Bruzzone]

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+// REQUIRES: target={{(aarch64|arm64).*}}
+
+// DEFINE: %{compile} = mlir-opt %s \
+// DEFINE:   -transform-interpreter -test-transform-dialect-erase-schedule \
+// DEFINE:   -cse -canonicalize -convert-vector-to-scf \
+// DEFINE:   -convert-vector-to-llvm="enable-arm-neon" -test-lower-to-llvm \
+// DEFINE:   -o %t
+
+// DEFINE: %{run} = %mcr_aarch64_cmd %t -e main -entry-point-result=void --march=aarch64 --mattr="+neon" \
+// DEFINE:    -shared-libs=%native_mlir_runner_utils,%native_mlir_c_runner_utils
+
+// RUN: rm -f %t && %{compile} && FileCheck %s --input-file=%t -check-prefix CHECK-IR && %{run} | FileCheck %s
+
+//===----------------------------------------------------------------------===//
+/// HIGH-LEVEL OVERVIEW
+///
+/// End-to-end test for computing matrix-multiplication (f32, accumulating to
+/// f32) using linalg.mmt4d. In particular, demonstrates how the following
+/// MLIR sequence (implemented in @matmul_via_mmt4d):
+///
+///   A_pack = linalg.pack A
+///   B_pack = linalg.pack B
+///   C_pack = linalg.pack C
+///   out_pack = linalg.mmt4d(A_pack, B_pack, C_pack)
+///
+/// is equivalent to:
+///
+///  linalg.matmul(A, B, C)
+///
+/// (implemented in @matmul).
+///
+/// NOTES ON IMPLEMENTATION
+/// 1. @matmul is only lowered via `-test-lower-to-llvm`, with no tiling or
+///    vectorization -- it's there to provide a reference check, not to
+///    demonstrate a lowering path.
+///
+/// 2. NEON has no instruction that multiplies two f32 matrices in one go, so
+///    the inner tile is (M0, N0, K0) = (4, 4, 1): every vector.contract is a
+///    rank-1 update, lowered to outer products, i.e. one `fmla` per row of
+///    the 4x4 accumulator tile.
+///
+/// 3. Packing is still worthwhile without a dedicated instruction: it gives
+///    the tiles a statically-known shape (no masking in the mmt4d loop) and
+///    makes them contiguous in memory.
----------------
FedericoBruzzone wrote:

I dropped it entirely :'D 
Also reworded the packing note to drop the same _without a dedicated instruction_ framing. 
Thanks.

https://github.com/llvm/llvm-project/pull/225063