[Relay][OP] Add reverse_reshape (#2503)

* Enable reverse in reshape

* Fix lint and typo

* Put reverse_reshape into a separate op

* Fix pylint

docs/langref/relay_op.rst

@@ -149,6 +149,7 @@ This level support backpropagation of broadcast operators. It is temporary.
    tvm.relay.layout_transform
    tvm.relay.device_copy
    tvm.relay.annotation.on_device
+   tvm.relay.reverse_reshape
 
 
 Level 1 Definitions
@@ -257,4 +258,5 @@ Level 10 Definitions
 .. autofunction:: tvm.relay.slice_like
 .. autofunction:: tvm.relay.layout_transform
 .. autofunction:: tvm.relay.device_copy
-.. autofunction:: tvm.relay.annotation.on_device
\ No newline at end of file
+.. autofunction:: tvm.relay.annotation.on_device
+.. autofunction:: tvm.relay.reverse_reshape

include/tvm/relay/attrs/transform.h

@@ -63,9 +63,13 @@ struct TransposeAttrs : public tvm::AttrsNode<TransposeAttrs> {
 /*! \brief Attributes used in reshape operators */
 struct ReshapeAttrs : public tvm::AttrsNode<ReshapeAttrs> {
   Array<Integer> newshape;
+  bool reverse;
   TVM_DECLARE_ATTRS(ReshapeAttrs, "relay.attrs.ReshapeAttrs") {
     TVM_ATTR_FIELD(newshape)
         .describe("The new shape. Should be compatible with the original shape.");
+    TVM_ATTR_FIELD(reverse)
+        .describe("Infer the special values from right to left if true")
+        .set_default(false);
   }
 };  // struct ReshapeAttrs
 

python/tvm/relay/frontend/nnvm_common.py

@@ -22,9 +22,10 @@ def _rename(new_op):
 
 
 def _reshape(inputs, attrs):
-    if attrs.get_bool("reverse", False):
-        raise RuntimeError("reshape do not support option reverse")
     shape = attrs.get_int_tuple("shape")
+    reverse = attrs.get_bool("reverse", False)
+    if reverse:
+        return _op.reverse_reshape(inputs[0], newshape=shape)
     return _op.reshape(inputs[0], newshape=shape)
 
 

python/tvm/relay/op/_transform.py

@@ -26,6 +26,7 @@ _reg.register_schedule("split", schedule_injective)
 _reg.register_schedule("take", schedule_injective)
 _reg.register_schedule("transpose", schedule_injective)
 _reg.register_schedule("where", schedule_broadcast)
+_reg.register_schedule("_contrib_reverse_reshape", schedule_injective)
 
 # layout_transform
 _reg.register_schedule("layout_transform", schedule_injective)

python/tvm/relay/op/transform.py

@@ -141,7 +141,7 @@ def reshape(data, newshape):
 
     Example::
 
-    - data.shape = (2,3,4), newshape = (-4,1,2,-2), result.shape =(1,2,3,4)
+    - data.shape = (2,3,4), newshape = (-4,1,2,-2), result.shape = (1,2,3,4)
     - data.shape = (2,3,4), newshape = (2,-4,-1,3,-2), result.shape = (2,1,3,4)
 
     Parameters
@@ -449,3 +449,34 @@ def layout_transform(data, src_layout, dst_layout):
         The transformed tensor.
     """
     return _make.layout_transform(data, src_layout, dst_layout)
+
+
+def reverse_reshape(data, newshape):
+    """Reshapes the input array where the special values are inferred from
+    right to left.
+
+    Example::
+
+    The special values have the same semantics as :py:class:`tvm.relay.reshape`.
+    The difference is that special values are inferred from right to left. It
+    can be explained in the example below::
+
+    - data.shape = (10,5,4), newshape = (-1,0), reshape results in (40,5)
+    - data.shape = (10,5,4), newshape = (-1,0), reverse_reshape results in (40,5)
+
+    Parameters
+    ----------
+    data : relay.Expr
+        The input data to the operator.
+
+    newshape : Union[int, Tuple[int], List[int]]
+        The new shape. Should be compatible with the original shape.
+
+    Returns
+    -------
+    result : relay.Expr
+        The reshaped result.
+    """
+    if isinstance(newshape, int):
+        newshape = [newshape]
+    return _make._contrib_reverse_reshape(data, list(newshape))

src/relay/op/tensor/transform.cc

@@ -382,20 +382,29 @@ bool ReshapeRel(const Array<Type>& types,
   }
 
   const auto* param = attrs.as<ReshapeAttrs>();
+  Array<IndexExpr> data_shape;
+  Array<Integer> newshape;
+  if (param->reverse) {
+    data_shape.assign(data->shape.rbegin(), data->shape.rend());
+    newshape.assign(param->newshape.rbegin(), param->newshape.rend());
+  } else {
+    data_shape = data->shape;
+    newshape = param->newshape;
+  }
   Array<IndexExpr> oshape;
   size_t src_idx = 0;
   int infer_idx = -1;
 
-  for (size_t i = 0; i < param->newshape.size(); ++i) {
-    int svalue = param->newshape[i]->value;
+  for (size_t i = 0; i < newshape.size(); ++i) {
+    int svalue = newshape[i]->value;
     // special flag handling for shape inference.
     if (svalue > 0) {
-      oshape.push_back(param->newshape[i]);
+      oshape.push_back(newshape[i]);
       ++src_idx;
     } else if (svalue == 0) {
       // keep same
-      CHECK_LT(src_idx, data->shape.size());
-      oshape.push_back(data->shape[src_idx++]);
+      CHECK_LT(src_idx, data_shape.size());
+      oshape.push_back(data_shape[src_idx++]);
     } else if (svalue == -1) {
       // inference based on rest
       CHECK_LT(infer_idx, 0)
@@ -405,42 +414,51 @@ bool ReshapeRel(const Array<Type>& types,
       ++src_idx;
     } else if (svalue == -2) {
       // copy all remaining dims from source
-      while (src_idx < data->shape.size()) {
-        oshape.push_back(data->shape[src_idx++]);
+      while (src_idx < data_shape.size()) {
+        oshape.push_back(data_shape[src_idx++]);
       }
     } else if (svalue == -3) {
       // merge two dims from source
-      CHECK_LT(src_idx + 1, data->shape.size());
-      IndexExpr d1 = data->shape[src_idx++];
-      IndexExpr d2 = data->shape[src_idx++];
+      CHECK_LT(src_idx + 1, data_shape.size());
+      IndexExpr d1 = data_shape[src_idx++];
+      IndexExpr d2 = data_shape[src_idx++];
       oshape.push_back(d1 * d2);
     } else if (svalue == -4) {
       // split the source dim s into two dims
       // read the left dim and then the right dim (either can be -1)
-      CHECK_LT(i + 2, param->newshape.size());
-      CHECK_LT(src_idx, data->shape.size());
-      IndexExpr d0 = data->shape[src_idx++];
-      Integer d1 = param->newshape[++i];
-      Integer d2 = param->newshape[++i];
+      CHECK_LT(i + 2, newshape.size());
+      CHECK_LT(src_idx, data_shape.size());
+      IndexExpr d0 = data_shape[src_idx++];
+      Integer d1 = newshape[++i];
+      Integer d2 = newshape[++i];
       if (d1->value == -1) {
         CHECK(d2->value != -1)
             << "Split dims cannot both be -1.";
         oshape.push_back(d0 / d2);
         oshape.push_back(d2);
       } else {
-        CHECK_EQ(d2->value, -1);
         oshape.push_back(d1);
-        oshape.push_back(d0 / d1);
+        if (d2->value == -1) {
+          oshape.push_back(d0 / d1);
+        } else {
+          oshape.push_back(d2);
+        }
       }
     }
   }
 
   if (infer_idx >= 0) {
     IndexExpr new_size = arith::ComputeReduce<tvm::ir::Mul>(oshape, 1);
-    IndexExpr old_size = arith::ComputeReduce<tvm::ir::Mul>(data->shape, 1);
+    IndexExpr old_size = arith::ComputeReduce<tvm::ir::Mul>(data_shape, 1);
     oshape.Set(infer_idx, old_size / new_size);
   }
-  reporter->Assign(types[1], TensorTypeNode::make(oshape, data->dtype));
+
+  if (param->reverse) {
+    reporter->Assign(types[1], TensorTypeNode::make(
+        Array<IndexExpr>(oshape.rbegin(), oshape.rend()), data->dtype));
+  } else {
+    reporter->Assign(types[1], TensorTypeNode::make(oshape, data->dtype));
+  }
   return true;
 }
 
@@ -457,6 +475,7 @@ Expr MakeReshape(Expr data,
                  Array<Integer> newshape) {
   auto attrs = make_node<ReshapeAttrs>();
   attrs->newshape = std::move(newshape);
+  attrs->reverse = false;
   static const Op& op = Op::Get("reshape");
   return CallNode::make(op, {data}, Attrs(attrs), {});
 }
@@ -1699,5 +1718,43 @@ the input array by output[n, c, h, w, C] = data[n, C*16+c, h, w]
 .set_support_level(5)
 .set_attr<FTVMCompute>("FTVMCompute", LayoutTransformCompute);
 
+
+/* relay._contrib_reverse_reshape */
+Expr MakeReverseReshape(Expr data,
+                        Array<Integer> newshape) {
+  auto attrs = make_node<ReshapeAttrs>();
+  attrs->newshape = std::move(newshape);
+  attrs->reverse = true;
+  static const Op& op = Op::Get("_contrib_reverse_reshape");
+  return CallNode::make(op, {data}, Attrs(attrs), {});
+}
+
+TVM_REGISTER_API("relay.op._make._contrib_reverse_reshape")
+.set_body([](const TVMArgs& args, TVMRetValue* rv) {
+    runtime::detail::unpack_call<Expr, 2>(MakeReverseReshape, args, rv);
+});
+
+RELAY_REGISTER_OP("_contrib_reverse_reshape")
+.describe(R"code(Reshapes the input array where the special values are inferred from
+right to left.
+
+Example::
+
+The special values have the same semantics as reshape. The difference is that
+special values are inferred from right to left. It can be explained in the
+example below::
+
+- data.shape = (10,5,4), newshape = (-1,0), reshape results in (40,5)
+- data.shape = (10,5,4), newshape = (-1,0), reverse_reshape results in (40,5)
+
+)code" TVM_ADD_FILELINE)
+.set_num_inputs(1)
+.set_attrs_type_key("relay.attrs.ReshapeAttrs")
+.add_argument("data", "Tensor", "The input tensor.")
+.set_support_level(10)
+.add_type_rel("Reshape", ReshapeRel)
+.set_attr<FTVMCompute>("FTVMCompute", ReshapeCompute)
+.set_attr<TOpPattern>("TOpPattern", kInjective);
+
 }  // namespace relay
 }  // namespace tvm

tests/python/relay/test_op_level10.py

@@ -121,8 +121,31 @@ def test_slice_like():
                       axes=(2, 3),
                       output=(1, 3, 112, 112))
 
+def test_reverse_reshape():
+    def verify_reverse_reshape(shape, newshape, oshape):
+        x = relay.var("x", relay.TensorType(shape, "float32"))
+        z = relay.reverse_reshape(x, newshape=newshape)
+        zz = relay.ir_pass.infer_type(z)
+        print(zz.checked_type)
+        assert "newshape=" in z.astext()
+        assert zz.checked_type == relay.ty.TensorType(oshape, "float32")
+
+        func = relay.Function([x], z)
+        x_data = np.random.uniform(low=-1, high=1, size=shape).astype("float32")
+        ref_res = np.reshape(x_data, oshape)
+        for target, ctx in ctx_list():
+            for kind in ["graph", "debug"]:
+                intrp = relay.create_executor(kind, ctx=ctx, target=target)
+                op_res = intrp.evaluate(func)(x_data)
+                tvm.testing.assert_allclose(op_res.asnumpy(), ref_res, rtol=1e-5)
+    verify_reverse_reshape((2, 3, 4), (4, 0, 2), (4, 3, 2))
+    verify_reverse_reshape((2, 3, 4), (2, 0, 0), (2, 3, 4))
+    verify_reverse_reshape((2, 3, 4), (0, -1), (3, 8))
+    verify_reverse_reshape((2, 3, 4), (-1, 0), (6, 4))
+    verify_reverse_reshape((2, 3, 4), (0, -3), (2, 12))
 
 if __name__ == "__main__":
     test_collapse_sum_like()
     test_broadcast_to_like()
     test_slice_like()
+    test_reverse_reshape()

tests/python/relay/test_op_level3.py

@@ -152,25 +152,36 @@ def test_reshape_infer_type():
         (n, t, 2000), "float32")
 
 def test_reshape():
-    def verify_reshape(shape, oshape):
-        x_data = np.random.uniform(low=-1, high=1, size=shape).astype("float32")
-        ref_res = np.reshape(x_data, oshape)
-
+    def verify_reshape(shape, newshape, oshape):
         x = relay.var("x", relay.TensorType(shape, "float32"))
-        z = relay.reshape(x, newshape=ref_res.shape)
+        z = relay.reshape(x, newshape=newshape)
         zz = relay.ir_pass.infer_type(z)
         assert "newshape=" in z.astext()
         assert zz.checked_type == relay.ty.TensorType(oshape, "float32")
 
         func = relay.Function([x], z)
-
+        x_data = np.random.uniform(low=-1, high=1, size=shape).astype("float32")
+        ref_res = np.reshape(x_data, oshape)
         for target, ctx in ctx_list():
             for kind in ["graph", "debug"]:
                 intrp = relay.create_executor(kind, ctx=ctx, target=target)
                 op_res = intrp.evaluate(func)(x_data)
                 tvm.testing.assert_allclose(op_res.asnumpy(), ref_res, rtol=1e-5)
-    verify_reshape((2, 3, 4), (8, 3))
-    verify_reshape((4, 7), (2, 7, 2))
+    verify_reshape((2, 3, 4), (8, 3), (8, 3))
+    verify_reshape((4, 7), (2, 7, 2), (2, 7, 2))
+    verify_reshape((2, 3, 4), (4, 0, 2), (4, 3, 2))
+    verify_reshape((2, 3, 4), (2, 0, 0), (2, 3, 4))
+    verify_reshape((2, 3, 4), (0, -1), (2, 12))
+    verify_reshape((2, 3, 4), (-1, 0), (8, 3))
+    verify_reshape((2, 3, 4), (2, -2), (2, 3, 4))
+    verify_reshape((2, 3, 4), (-2, 1, 1), (2, 3, 4, 1, 1))
+    verify_reshape((2, 3, 4), (-3, 4), (6, 4))
+    verify_reshape((2, 3, 4, 5), (-3, -3), (6, 20))
+    verify_reshape((2, 3, 4), (0, -3), (2, 12))
+    verify_reshape((2, 3, 4), (-3, -2), (6, 4))
+    verify_reshape((2, 3, 4), (-4, 1, 2, -2), (1, 2, 3, 4))
+    verify_reshape((2, 3, 4), (2, -4, -1, 3, -2), (2, 1, 3, 4))
+
 
 def test_reshape_like_infer_type():
     # concrete shape