[Mlir-commits] [mlir] [NFC] Simplify the tiling implementation using cloning. (PR #72178)

[lorenzo chelini]

================
@@ -544,17 +554,56 @@ mlir::scf::tileAndFuseProducerOfSlice(RewriterBase &rewriter,
                                         loops);
   if (!fusableProducer)
     return std::nullopt;
+  unsigned resultNumber = fusableProducer.getResultNumber();
 
-  // 2. Generate the tiled implementation of the producer of the source
   OpBuilder::InsertionGuard g(rewriter);
   rewriter.setInsertionPoint(candidateSliceOp);
+
+  // 2. Clone the fused producer
+  // 2a. Compute the destination operands to use for the cloned operation.
+  SmallVector<Value> origDestinationTensors, clonedOpDestinationTensors;
+  Operation *fusableProducerOp = fusableProducer.getOwner();
+  if (isa<DestinationStyleOpInterface>(fusableProducerOp)) {
+    if (failed(tensor::getOrCreateDestinations(
+            rewriter, fusableProducerOp->getLoc(), fusableProducerOp,
+            origDestinationTensors))) {
+      return std::nullopt;
+    }
+  }
+  clonedOpDestinationTensors = origDestinationTensors;
+  if (destinationInitArg &&
+      isa<DestinationStyleOpInterface>(fusableProducerOp)) {
+    // 2b. If the producer is also destination style, then to maintain the
+    // destination passing style, update the destination of the producer to be
+    // the source of the slice.
+    clonedOpDestinationTensors[resultNumber] = candidateSliceOp.getSource();
+  }
+  // 2c. Clone the fused producer.
+  Operation *clonedProducerOp = cloneOpAndUpdateDestinationArgs(
+      rewriter, fusableProducerOp, clonedOpDestinationTensors);
+  // 2d. Update the source of the candidateSlice to be the cloned producer.
+  //     Easier to just clone the slice with different source since replacements
+  //     and DCE of cloned ops becomes easier
+  SmallVector<Value> candidateSliceOpOperands =
+      llvm::to_vector(candidateSliceOp->getOperands());
+  candidateSliceOpOperands[0] = clonedProducerOp->getResult(resultNumber);
+  tensor::ExtractSliceOp clonedCandidateSliceOp =
+      mlir::clone(rewriter, candidateSliceOp,
----------------
chelini wrote:

Is this a good way of cloning the op? My understanding was always to use the builder to signal the listener about IR mutation (@matthias-springer).

https://github.com/llvm/llvm-project/pull/72178