address review comments

Author: javedabsar1

mlir/include/mlir/Dialect/Linalg/Passes.td

@@ -182,17 +182,17 @@ def LinalgConvertToDPSPass : Pass<"linalg-convert-to-dps"> {
     ```
     gets rewritten as:
     ```mlir
-       %c0 = arith.constant 0 : index
-       %dim = tensor.dim %arg0, %c0 : tensor<?xi32>
-       %0 = tensor.empty(%dim) : tensor<?xf32>
-       %1 = linalg.generic
-           {indexing_maps = [#map, #map], iterator_types = ["parallel"]}
-           ins(%arg0 : tensor<?xi32>) outs(%0 : tensor<?xf32>) {
+      %c0 = arith.constant 0 : index
+      %dim = tensor.dim %arg0, %c0 : tensor<?xi32>
+      %0 = tensor.empty(%dim) : tensor<?xf32>
+      %1 = linalg.generic
+             {indexing_maps = [#map, #map], iterator_types = ["parallel"]}
+             ins(%arg0 : tensor<?xi32>) outs(%0 : tensor<?xf32>) {
            ^bb0(%in: i32, %out: f32):
              %2 = arith.uitofp %in : i32 to f32
              linalg.yield %2 : f32
-       } -> tensor<?xf32>
-     ```
+      } -> tensor<?xf32>
+    ```
    }];
   let dependentDialects = ["linalg::LinalgDialect"];
 }

mlir/lib/Dialect/Linalg/TransformOps/LinalgTransformOps.cpp

@@ -58,10 +58,10 @@ using namespace mlir::transform;
 /// pattern failed to apply. Extra arguments are forwarded to the pattern
 /// constructor.
 template <typename PatternTy, typename... Args>
-static FailureOr<LinalgOp> tryApply(Operation *operation, Args &&... args) {
+static FailureOr<LinalgOp> tryApply(Operation *operation, Args &&...args) {
   // Check if the given operation has the type expected by the pattern.
-  using OpTy = typename llvm::function_traits<decltype(
-      &PatternTy::returningMatchAndRewrite)>::template arg_t<0>;
+  using OpTy = typename llvm::function_traits<
+      decltype(&PatternTy::returningMatchAndRewrite)>::template arg_t<0>;
   auto op = dyn_cast<OpTy>(operation);
   if (!op)
     return failure();

mlir/lib/Dialect/Linalg/Transforms/ConvertToDestinationStyle.cpp

@@ -31,8 +31,6 @@ namespace mlir {
 #include "mlir/Dialect/Linalg/Passes.h.inc"
 } // namespace mlir
 
-#define DEBUG_TYPE "linalg-convert-to-dps"
-
 using namespace mlir;
 using namespace mlir::tensor;
 
@@ -612,10 +610,23 @@ Value linalg::bufferizeToAllocation(
 }
 
 namespace {
+/// Rewrites an arith op operating on tensors, e.g.
+///  `%z = arith.addf %x, %y : tensor<5xf32>`
+/// into an equivalent linalg.generic in destination-passing-style.
+/// ```mlir
+/// %0 = tensor.empty() : tensor<5xf32>
+/// %1 = linalg.generic ...
+///        ins(%x, %y : tensor<5xf32>, tensor<5xf32>)
+///        outs(%0 : tensor<5xf32>) {
+///      ^bb0(%in: f32, %in_0: f32, %out: f32):
+///         %2 = arith.addf %in, %in_0 : f32
+///         linalg.yield %2 : f32
+///     } -> tensor<5xf32>
 template <typename OpTy>
 FailureOr<Operation *>
 rewriteArithInDestinationPassingStyle(RewriterBase &rewriter, OpTy op) {
-  // reject ops such as `arith.constant` and `arith.select`.
+  // Reject ops such as `arith.constant` and `arith.select`.
+  // constants don't need dps conversion and select is a a `todo`.
   auto numOperands = op->getNumOperands();
   if (numOperands == 0 || numOperands > 2)
     return failure();
@@ -630,8 +641,8 @@ rewriteArithInDestinationPassingStyle(RewriterBase &rewriter, OpTy op) {
   OpBuilder::InsertionGuard g(rewriter);
   auto dynSizes = reifyOrComputeDynamicSizes(rewriter, op->getOperand(0));
 
-  // Create tensor.empty.
-  Value empty = tensor::EmptyOp::create(rewriter, loc, resultType, dynSizes);
+  // Create tensor.empty for `outs` of destination-passing-style.
+  Value outs = tensor::EmptyOp::create(rewriter, loc, resultType, dynSizes);
 
   // Create linalg.generic
   auto rank = tensorType.getRank();
@@ -642,7 +653,7 @@ rewriteArithInDestinationPassingStyle(RewriterBase &rewriter, OpTy op) {
   auto genericOp = linalg::GenericOp::create(
       rewriter, loc, tensorType,
       op->getOperands(), // inputs
-      ValueRange{empty}, // outputs
+      ValueRange{outs}, // outputs
       indexingMaps, iteratorTypes,
       [&](OpBuilder &builder, Location loc, ValueRange args) {
         Value res;