Add MLIR generated kernel for Angle kernel.

This also requires a canonicalization pattern to remove a redundant dynamic
reshape from rank 1 to rank 1.

PiperOrigin-RevId: 355113135

lib/Dialect/mhlo/IR/hlo_ops.cc

@@ -1310,6 +1310,40 @@ class DynamicReshapeOpNotActuallyDynamic
   }
 };
 
+// Canonicalizes
+// %0 = some_op(%tensor)
+// %1 = "mhlo.dynamic_reshape"(%0, %shape)
+//      (tensor<?xT>, tensor<1xindex>) -> tensor<?xT>
+// ... uses of %1.
+//
+// into
+//
+// ... uses of %0.
+// This canonicalization is only correct if the input is correct!
+// TODO(b/178779691): Use a more sophisticated canonicalization that preserves
+// errors in input, and still allows us to get rid of redundant reshapes.
+class RemoveRedundantRank1DynamicReshape
+    : public OpRewritePattern<DynamicReshapeOp> {
+ public:
+  using OpRewritePattern::OpRewritePattern;
+  LogicalResult matchAndRewrite(DynamicReshapeOp op,
+                                PatternRewriter& rewriter) const override {
+    auto type = op.result().getType().dyn_cast<RankedTensorType>();
+    if (!type || type.getRank() != 1 || type.hasStaticShape()) {
+      return rewriter.notifyMatchFailure(
+          op, "requires rank 1 shape tensor with dynamic dimension");
+    }
+    auto operand_type = op.operand().getType().dyn_cast<RankedTensorType>();
+    if (!operand_type || operand_type.getRank() != 1 ||
+        operand_type.hasStaticShape()) {
+      return rewriter.notifyMatchFailure(
+          op, "requires rank 1 shape tensor with dynamic dimension");
+    }
+    rewriter.replaceOp(op, {op.operand()});
+    return success();
+  }
+};
+
 // Canonicalizes
 // %0 = "mhlo.dynamic_reshape"(%tensor, %shape)
 // %1 = same_operands_and_result_shape_op(%tensor)
@@ -1354,6 +1388,7 @@ void DynamicReshapeOp::getCanonicalizationPatterns(
       DynamicReshapeOpSameShapeOpResult,
       RemoveRedundantDynamicBroadcast,
       RemoveRedundantDynamicReshape,
+      RemoveRedundantRank1DynamicReshape,
       ShapeOfDynamicReshape
     >(context);
   // clang-format on

tests/canonicalize.mlir

@@ -594,12 +594,26 @@ func @shape_of_dynamic_reshape(%arg0: tensor<*xf32>, %shape: tensor<2xindex>) ->
   return %1 : tensor<2xindex>
 }
 
+// CHECK-LABEL: func @dynamic_reshape_rank_1_to_rank_1
+// CHECK-SAME: [[ARG0:%[a-zA-Z0-9]+]]
+func @dynamic_reshape_rank_1_to_rank_1(%arg0: tensor<?xcomplex<f32>>,
+    %shape: tensor<?xindex>) -> tensor<?xf32> {
+  // CHECK: [[RES:%[a-zA-Z0-9]+]] = "mhlo.real"([[ARG0]]) : (tensor<?xcomplex<f32>>) -> tensor<?xf32>
+  // CHECK: return [[RES]]
+  %0 = "mhlo.real"(%arg0): (tensor<?xcomplex<f32>>) -> tensor<?xf32>
+  %1 = shape.shape_of %arg0 : tensor<?xcomplex<f32>> -> tensor<1xindex>
+  %2 = shape.num_elements %1 : tensor<1xindex> -> index
+  %3 = tensor.from_elements %2 : tensor<1xindex>
+  %4 = "mhlo.dynamic_reshape"(%0, %3)
+    : (tensor<?xf32>, tensor<1xindex>) -> tensor<?xf32>
+  return %4 : tensor<?xf32>
+}
+
 // CHECK-LABEL: func @dynamic_reshape_of_dynamic_reshape
 // CHECK-SAME: [[ARG0:%[a-zA-Z0-9]+]]
 // CHECK-SAME: [[ARG1:%[a-zA-Z0-9]+]]
 func @dynamic_reshape_of_dynamic_reshape(%arg0: tensor<?xf16>, %shape: tensor<?xindex>) -> tensor<?xf16> {
-  // CHECK: [[RES:%[a-zA-Z0-9]+]] = "mhlo.dynamic_reshape"([[ARG0]], %{{[a-zA-Z0-9]+}}) : (tensor<?xf16>, tensor<1xindex>) -> tensor<?xf16>
+  // CHECK: return [[ARG0]]
-  // CHECK: return [[RES]]
   %0 = "mhlo.dynamic_reshape"(%arg0, %shape) : (tensor<?xf16>, tensor<?xindex>) -> tensor<*xf16>
   %1 = shape.shape_of %0 : tensor<*xf16> -> tensor<?xindex>
   %2 = shape.num_elements %1 : tensor<?xindex> -> index