[Mlir-commits] [mlir] [mlir][ArmSME] Fix loop bounds of masked loads/stores (PR #78983)

[Cullen Rhodes]

================
@@ -47,99 +48,103 @@ void getMemrefIndices(ValueRange indices, unsigned rank, Value tileSliceIndex,
 
   if (rank == 2)
     outIndices.push_back(indices[1]);
-}
 
-/// Lower `arm_sme.tile_load` to a loop over the tile slices and load each slice
-/// using `arm_sme.load_tile_slice`.
-///
-///  BEFORE:
-///  ```mlir
-///  %tile = arm_sme.tile_load %src[%c0, %c0] :
-///    memref<?x?xi32>, vector<[4]x[4]xi32>
-///  ```
-///
-///  AFTER:
-///  ```mlir
-///  %ptrue_s = arith.constant dense<true> : vector<[4]xi1>
-///  %init_tile = arm_sme.get_tile : vector<[4]x[4]xi32>
-///  %vscale = vector.vscale
-///  %c0 = arith.constant 0 : index
-///  %c1 = arith.constant 1 : index
-///  %min_svl_s = arith.constant 4 : index
-///  %svl_s = arith.muli %min_svl_s, %vscale : index
-///  %tile = scf.for %tile_slice_idx = %c0 to %svl_s step %c1
-///                iter_args(%iter_tile = %init_tile) -> (vector<[4]x[4]xi32>) {
-///    %tile_update = arm_sme.load_tile_slice %src[%tile_slice_idx],
-///      %ptrue_s, %iter_tile, %tile_slice_idx
-///        : memref<?x?xi32>, vector<[4]xi1>, vector<[4]x[4]xi32>
-///    scf.yield %tile_update : vector<[4]x[4]xi32>
-///  }
-///  ```
-struct TileLoadOpConversion : public OpRewritePattern<arm_sme::TileLoadOp> {
-  using OpRewritePattern<arm_sme::TileLoadOp>::OpRewritePattern;
-
-  LogicalResult matchAndRewrite(arm_sme::TileLoadOp tileLoadOp,
-                                PatternRewriter &rewriter) const override {
-    if (tileLoadOp.getMask())
-      return rewriter.notifyMatchFailure(tileLoadOp,
-                                         "op has mask, apply masked patterns");
-
-    OpBuilder::InsertionGuard g(rewriter);
-    auto loc = tileLoadOp.getLoc();
-    auto tileType = tileLoadOp.getVectorType();
-    auto tileElementType = tileType.getElementType();
-
-    // Allocate a new SME tile.
-    auto initTile = tileLoadOp.createOpAndForwardTileId<arm_sme::GetTileOp>(
-        rewriter, loc, tileType);
+  return outIndices;
+}
 
-    // Create a loop that loads each ZA tile slice from memory.
-    auto step = rewriter.create<arith::ConstantIndexOp>(loc, 1);
-    auto minTileSlices = rewriter.create<arith::ConstantIndexOp>(
-        loc, arm_sme::getSMETileSliceMinNumElts(tileElementType));
-    auto vscale =
-        rewriter.create<vector::VectorScaleOp>(loc, rewriter.getIndexType());
-    auto lowerBound = rewriter.create<arith::ConstantIndexOp>(loc, 0);
-    // This describes both the number of ZA tile slices and the number of
-    // elements in a vector of SVL bits for a given element type (SVL_B, SVL_H,
-    // ..., SVL_Q).
-    auto numTileSlices =
-        rewriter.create<arith::MulIOp>(loc, minTileSlices, vscale);
-    auto forOp = rewriter.create<scf::ForOp>(loc, lowerBound, numTileSlices,
-                                             step, ValueRange{initTile});
+/// Creates an scf.for for the load/store of an ArmSME tile.
+FailureOr<scf::ForOp> createLoadStoreForOverTileSlices(
+    PatternRewriter &rewriter, Location loc, VectorType tileType,
----------------
c-rhodes wrote:

I came across [ImplicitLocOpBuilder](https://mlir.llvm.org/doxygen/classmlir_1_1ImplicitLocOpBuilder.html#a6b440b25bf12be7622e136c5111419d7) the other day which can be used to combine rewriter/loc which is pretty nice and could simplify the args a little, it's used like:
```
ImplicitLocOpBuilder b(getLoc(), rewriter);
```

https://github.com/llvm/llvm-project/pull/78983