From 526dfe3f4d33eea3d32cd8730e5dcbc1b9010d3f Mon Sep 17 00:00:00 2001
From: MaheshRavishankar <ravishankarm@google.com>
Date: Thu, 18 Nov 2021 09:27:27 -0800
Subject: [PATCH] [mlir][Linalg] Do not return failure when all tile sizes are
 zero.

Returning failure when tile sizes are all zero prevents the change in
the marker. This makes pattern rewriter run the pattern multiple times
only to exit when it hits a limit. Instead just clone the operation
(since tiling is essentially cloning in this case). Then the
transformation filter kicks in to avoid the pattern rewriter to be
invoked many times.

Differential Revision: https://reviews.llvm.org/D113949
---
 mlir/lib/Dialect/Linalg/Transforms/Tiling.cpp |  9 +++++++--
 mlir/test/Dialect/Linalg/tile-zero.mlir       | 12 ++++++++++++
 2 files changed, 19 insertions(+), 2 deletions(-)
 create mode 100644 mlir/test/Dialect/Linalg/tile-zero.mlir

diff --git a/mlir/lib/Dialect/Linalg/Transforms/Tiling.cpp b/mlir/lib/Dialect/Linalg/Transforms/Tiling.cpp
index 8ccdb7f62246..0a4115366908 100644
--- a/mlir/lib/Dialect/Linalg/Transforms/Tiling.cpp
+++ b/mlir/lib/Dialect/Linalg/Transforms/Tiling.cpp
@@ -159,8 +159,13 @@ tileLinalgOpImpl(OpBuilder &b, LinalgOp op, ValueRange tileSizes,
   // Initial tile sizes may be too big, only take the first nLoops.
   tileSizes = tileSizes.take_front(nLoops);
 
-  if (llvm::all_of(tileSizes, isZero))
-    return failure();
+  if (llvm::all_of(tileSizes, isZero)) {
+    TiledLinalgOp tiledOp;
+    tiledOp.op = cast<LinalgOp>(b.clone(*op.getOperation()));
+    tiledOp.tensorResults.assign(tiledOp.op->result_begin(),
+                                 tiledOp.op->result_end());
+    return tiledOp;
+  }
 
   // 1. Build the tiled loop ranges.
   auto allShapeSizes = op.createFlatListOfOperandDims(b, op.getLoc());
diff --git a/mlir/test/Dialect/Linalg/tile-zero.mlir b/mlir/test/Dialect/Linalg/tile-zero.mlir
new file mode 100644
index 000000000000..1a09906e52ce
--- /dev/null
+++ b/mlir/test/Dialect/Linalg/tile-zero.mlir
@@ -0,0 +1,12 @@
+// RUN: mlir-opt -test-linalg-transform-patterns=test-tile-pattern %s | FileCheck %s
+
+func @matmul_zero_tile(
+  %arg0: tensor<?x?xf32>, %arg1 : tensor<?x?xf32>, %arg2 : tensor<?x?xf32>) -> tensor<?x?xf32> {
+  %0 = linalg.matmul {__internal_linalg_transform__ = "tile"}
+      ins(%arg0, %arg1 : tensor<?x?xf32>, tensor<?x?xf32>)
+      outs(%arg2 : tensor<?x?xf32>) -> tensor<?x?xf32>
+  return %0 : tensor<?x?xf32>
+}
+// CHECK-LABEL: matmul_zero_tile
+//       CHECK:   linalg.matmul
+//   CHECK-NOT:   __internal_linalg_transform__