Add an abstract backprop op type (#240)

* Start adding the backprop op type.

* More backprop ops.

* Finish the backprop op.

candle-core/src/op.rs

@@ -58,7 +58,7 @@ pub enum UnaryOp {
 }
 
 #[derive(Clone)]
-pub(crate) enum Op {
+pub enum Op {
     Binary(Tensor, Tensor, BinaryOp),
     Unary(Tensor, UnaryOp),
     Cmp(Tensor, CmpOp),
@@ -512,3 +512,63 @@ impl UnaryOpT for Relu {
         v
     }
 }
+
+/// `BackpropOp` is a wrapper around `Option<Op>`. The main goal is to ensure that dependencies are
+/// properly checked when creating a new value
+#[derive(Clone)]
+pub struct BackpropOp(Option<Op>);
+
+impl BackpropOp {
+    pub(crate) fn none() -> Self {
+        BackpropOp(None)
+    }
+
+    pub(crate) fn new1(arg: &Tensor, f: impl Fn(Tensor) -> Op) -> Self {
+        let op = if arg.track_op() {
+            Some(f(arg.clone()))
+        } else {
+            None
+        };
+        Self(op)
+    }
+
+    pub(crate) fn new2(arg1: &Tensor, arg2: &Tensor, f: impl Fn(Tensor, Tensor) -> Op) -> Self {
+        let op = if arg1.track_op() || arg2.track_op() {
+            Some(f(arg1.clone(), arg2.clone()))
+        } else {
+            None
+        };
+        Self(op)
+    }
+
+    pub(crate) fn new3(
+        arg1: &Tensor,
+        arg2: &Tensor,
+        arg3: &Tensor,
+        f: impl Fn(Tensor, Tensor, Tensor) -> Op,
+    ) -> Self {
+        let op = if arg1.track_op() || arg2.track_op() || arg3.track_op() {
+            Some(f(arg1.clone(), arg2.clone(), arg3.clone()))
+        } else {
+            None
+        };
+        Self(op)
+    }
+
+    pub(crate) fn new<A: AsRef<Tensor>>(args: &[A], f: impl Fn(Vec<Tensor>) -> Op) -> Self {
+        let op = if args.iter().any(|arg| arg.as_ref().track_op()) {
+            let args: Vec<Tensor> = args.iter().map(|arg| arg.as_ref().clone()).collect();
+            Some(f(args))
+        } else {
+            None
+        };
+        Self(op)
+    }
+}
+
+impl std::ops::Deref for BackpropOp {
+    type Target = Option<Op>;
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}

candle-core/src/tensor.rs

@@ -1,5 +1,7 @@
 use crate::backend::{BackendDevice, BackendStorage};
-use crate::op::{BinaryOp, CmpOp, CustomOp1, CustomOp2, CustomOp3, Op, ReduceOp, UnaryOp};
+use crate::op::{
+    BackpropOp, BinaryOp, CmpOp, CustomOp1, CustomOp2, CustomOp3, Op, ReduceOp, UnaryOp,
+};
 use crate::shape::{Dim, Dims};
 use crate::{storage::Storage, DType, Device, Error, Layout, Result, Shape};
 use std::sync::{Arc, RwLock};
@@ -33,7 +35,7 @@ pub struct Tensor_ {
     // that's tricky to encode in the current setup.
     storage: Arc<RwLock<Storage>>,
     layout: Layout,
-    op: Option<Op>,
+    op: BackpropOp,
     is_variable: bool,
     dtype: DType,
     device: Device,
@@ -79,11 +81,7 @@ macro_rules! unary_op {
             let storage = self
                 .storage()
                 .unary_impl::<crate::op::$op_name>(self.layout())?;
-            let op = if self.track_op() {
+            let op = BackpropOp::new1(self, |s| Op::Unary(s, UnaryOp::$op_name));
-                Some(Op::Unary(self.clone(), UnaryOp::$op_name))
-            } else {
-                None
-            };
             Ok(from_storage(storage, shape.clone(), op, false))
         }
     };
@@ -98,11 +96,7 @@ macro_rules! binary_op {
                 self.layout(),
                 rhs.layout(),
             )?;
-            let op = if self.track_op() || rhs.track_op() {
+            let op = BackpropOp::new2(self, rhs, |t1, t2| Op::Binary(t1, t2, BinaryOp::$op_name));
-                Some(Op::Binary(self.clone(), rhs.clone(), BinaryOp::$op_name))
-            } else {
-                None
-            };
             Ok(from_storage(storage, shape.clone(), op, false))
         }
     };
@@ -131,7 +125,7 @@ macro_rules! broadcast_binary_op {
 fn from_storage<S: Into<Shape>>(
     storage: Storage,
     shape: S,
-    op: Option<Op>,
+    op: BackpropOp,
     is_variable: bool,
 ) -> Tensor {
     let dtype = storage.dtype();
@@ -155,13 +149,14 @@ impl Tensor {
         device: &Device,
         is_variable: bool,
     ) -> Result<Self> {
+        let none = BackpropOp::none();
         if is_variable {
             let shape = shape.into();
             let storage = device.ones(&shape, dtype)?;
-            Ok(from_storage(storage, shape, None, is_variable))
+            Ok(from_storage(storage, shape, none, is_variable))
         } else {
             let storage = device.ones(&crate::shape::SCALAR, dtype)?;
-            from_storage(storage, crate::shape::SCALAR, None, is_variable).broadcast_as(shape)
+            from_storage(storage, crate::shape::SCALAR, none, is_variable).broadcast_as(shape)
         }
     }
 
@@ -199,13 +194,14 @@ impl Tensor {
         device: &Device,
         is_variable: bool,
     ) -> Result<Self> {
+        let none = BackpropOp::none();
         if is_variable {
             let shape = shape.into();
             let storage = device.zeros(&shape, dtype)?;
-            Ok(from_storage(storage, shape, None, is_variable))
+            Ok(from_storage(storage, shape, none, is_variable))
         } else {
             let storage = device.zeros(&crate::shape::SCALAR, dtype)?;
-            from_storage(storage, crate::shape::SCALAR, None, is_variable).broadcast_as(shape)
+            from_storage(storage, crate::shape::SCALAR, none, is_variable).broadcast_as(shape)
         }
     }
 
@@ -246,7 +242,8 @@ impl Tensor {
     ) -> Result<Self> {
         let s = s.into();
         let storage = device.rand_uniform(&s, dtype, lo, up)?;
-        Ok(from_storage(storage, s, None, is_variable))
+        let none = BackpropOp::none();
+        Ok(from_storage(storage, s, none, is_variable))
     }
 
     /// Creates a new tensor initialized with values sampled uniformly between `lo` and `up`.
@@ -270,7 +267,8 @@ impl Tensor {
     ) -> Result<Self> {
         let s = s.into();
         let storage = device.rand_normal(&s, dtype, mean, std)?;
-        Ok(from_storage(storage, s, None, is_variable))
+        let none = BackpropOp::none();
+        Ok(from_storage(storage, s, none, is_variable))
     }
 
     /// Creates a new tensor initialized with values sampled from a normal distribution with the
@@ -297,7 +295,8 @@ impl Tensor {
             return Err(Error::ShapeMismatch { buffer_size, shape }.bt());
         }
         let storage = device.storage(array)?;
-        Ok(from_storage(storage, shape, None, is_variable))
+        let none = BackpropOp::none();
+        Ok(from_storage(storage, shape, none, is_variable))
     }
 
     /// Creates a new tensor on the specified device using the content and shape of the input.
@@ -352,7 +351,8 @@ impl Tensor {
             return Err(Error::ShapeMismatch { buffer_size, shape }.bt());
         }
         let storage = device.storage_owned(data)?;
-        Ok(from_storage(storage, shape, None, is_variable))
+        let none = BackpropOp::none();
+        Ok(from_storage(storage, shape, none, is_variable))
     }
 
     /// Creates a new tensor initialized with values from the input vector. The number of elements
@@ -500,26 +500,14 @@ impl Tensor {
     /// ```
     pub fn affine(&self, mul: f64, add: f64) -> Result<Self> {
         let storage = self.storage().affine(self.layout(), mul, add)?;
-        let op = if self.track_op() {
+        let op = BackpropOp::new1(self, |arg| Op::Affine { arg, mul, add });
-            Some(Op::Affine {
-                arg: self.clone(),
-                mul,
-                add,
-            })
-        } else {
-            None
-        };
         Ok(from_storage(storage, self.shape(), op, false))
     }
 
     /// Applies the Exponential Linear Unit (ELU) function on each element of the input tensor.
     pub fn elu(&self, alpha: f64) -> Result<Self> {
         let storage = self.storage().elu(self.layout(), alpha)?;
-        let op = if self.track_op() {
+        let op = BackpropOp::new1(self, |t| Op::Elu(t, alpha));
-            Some(Op::Elu(self.clone(), alpha))
-        } else {
-            None
-        };
         Ok(from_storage(storage, self.shape(), op, false))
     }
 
@@ -554,11 +542,7 @@ impl Tensor {
         if start == 0 && dims[dim] == len {
             Ok(self.clone())
         } else {
-            let op = if self.track_op() {
+            let op = BackpropOp::new1(self, |t| Op::Narrow(t, dim, start, len));
-                Some(Op::Narrow(self.clone(), dim, start, len))
-            } else {
-                None
-            };
             let layout = self.layout().narrow(dim, start, len)?;
             let tensor_ = Tensor_ {
                 id: TensorId::new(),
@@ -602,11 +586,7 @@ impl Tensor {
             let mut storage = self.storage().unary_impl::<crate::op::Exp>(self.layout())?;
             // The resulting storage is contiguous.
             storage.divide_by_sum_over_dim(shape, dim)?;
-            let op = if self.track_op() {
+            let op = BackpropOp::new1(self, |arg| Op::Softmax(arg, dim));
-                Some(Op::Softmax(self.clone(), dim))
-            } else {
-                None
-            };
             Ok(from_storage(storage, shape.clone(), op, false))
         }
     }
@@ -638,11 +618,7 @@ impl Tensor {
         let storage = self.storage().reduce_op(op, self.layout(), &[dim])?;
         let mut dims = self.dims().to_vec();
         dims[dim] = 1;
-        let op = if self.track_op() {
+        let op = BackpropOp::new1(self, |arg| Op::Reduce(arg, op, dims.to_vec()));
-            Some(Op::Reduce(self.clone(), op, dims.to_vec()))
-        } else {
-            None
-        };
         let res = from_storage(storage, dims, op, false);
         if keepdim {
             Ok(res)
@@ -660,11 +636,7 @@ impl Tensor {
         for &sum_dim in sum_dims.iter() {
             dims[sum_dim] = 1
         }
-        let op = if self.track_op() {
+        let op = BackpropOp::new1(self, |a| Op::Reduce(a, ReduceOp::Sum, dims.to_vec()));
-            Some(Op::Reduce(self.clone(), ReduceOp::Sum, dims.to_vec()))
-        } else {
-            None
-        };
         let sum = from_storage(storage, dims, op, false);
         if keepdim {
             Ok(sum)
@@ -738,11 +710,7 @@ impl Tensor {
         let storage = self
             .storage()
             .cmp(op, &rhs.storage(), self.layout(), rhs.layout())?;
-        let op = if self.track_op() {
+        let op = BackpropOp::new1(self, |a| Op::Cmp(a, op));
-            Some(Op::Cmp(self.clone(), op))
-        } else {
-            None
-        };
         Ok(from_storage(storage, shape.dims(), op, false))
     }
 
@@ -807,16 +775,12 @@ impl Tensor {
         let storage =
             self.storage()
                 .conv1d(self.layout(), &kernel.storage(), kernel.layout(), &params)?;
-        let op = if self.track_op() || kernel.track_op() {
+        let op = BackpropOp::new2(self, kernel, |arg, kernel| Op::Conv1D {
-            Some(Op::Conv1D {
+            arg,
-                arg: self.clone(),
+            kernel,
-                kernel: kernel.clone(),
             padding,
             stride,
-            })
+        });
-        } else {
-            None
-        };
         let out_dims = params.out_dims();
         Ok(from_storage(storage, out_dims, op, false))
     }
@@ -867,11 +831,7 @@ impl Tensor {
             self.layout(),
             rhs.layout(),
         )?;
-        let op = if self.track_op() || rhs.track_op() {
+        let op = BackpropOp::new2(self, rhs, Op::Matmul);
-            Some(Op::Matmul(self.clone(), rhs.clone()))
-        } else {
-            None
-        };
         Ok(from_storage(storage, c_shape, op, false))
     }
 
@@ -888,15 +848,7 @@ impl Tensor {
             &on_false.storage(),
             on_false.layout(),
         )?;
-        let op = if self.track_op() || on_true.track_op() || on_false.track_op() {
+        let op = BackpropOp::new3(self, on_true, on_false, Op::WhereCond);
-            Some(Op::WhereCond(
-                self.clone(),
-                on_true.clone(),
-                on_false.clone(),
-            ))
-        } else {
-            None
-        };
         Ok(from_storage(storage, shape, op, false))
     }
 
@@ -937,11 +889,7 @@ impl Tensor {
             .storage()
             .embedding(ids.layout(), &rhs.storage(), rhs.layout())?;
         let shape: Shape = (seq_len, hidden_size).into();
-        let op = if ids.track_op() || rhs.track_op() {
+        let op = BackpropOp::new2(ids, rhs, Op::Embedding);
-            Some(Op::Embedding(ids.clone(), rhs.clone()))
-        } else {
-            None
-        };
         Ok(from_storage(storage, shape, op, false))
     }
 
@@ -983,16 +931,9 @@ impl Tensor {
             source.layout(),
             dim,
         )?;
-        let op = if indexes.track_op() || self.track_op() {
+        let op = BackpropOp::new3(self, indexes, source, |t1, t2, t3| {
-            Some(Op::ScatterAdd(
+            Op::ScatterAdd(t1, t2, t3, dim)
-                self.clone(),
+        });
-                indexes.clone(),
-                source.clone(),
-                dim,
-            ))
-        } else {
-            None
-        };
         Ok(from_storage(storage, self.shape(), op, false))
     }
 
@@ -1038,16 +979,9 @@ impl Tensor {
             source.layout(),
             dim,
         )?;
-        let op = if indexes.track_op() || self.track_op() {
+        let op = BackpropOp::new3(self, indexes, source, |t1, t2, t3| {
-            Some(Op::IndexAdd(
+            Op::IndexAdd(t1, t2, t3, dim)
-                self.clone(),
+        });
-                indexes.clone(),
-                source.clone(),
-                dim,
-            ))
-        } else {
-            None
-        };
         Ok(from_storage(storage, self.shape(), op, false))
     }
 
@@ -1077,11 +1011,7 @@ impl Tensor {
         let storage =
             self.storage()
                 .gather(self.layout(), &indexes.storage(), indexes.layout(), dim)?;
-        let op = if indexes.track_op() || self.track_op() {
+        let op = BackpropOp::new2(self, indexes, |t1, t2| Op::Gather(t1, t2, dim));
-            Some(Op::Gather(self.clone(), indexes.clone(), dim))
-        } else {
-            None
-        };
         Ok(from_storage(storage, indexes.shape(), op, false))
     }
 
@@ -1104,11 +1034,7 @@ impl Tensor {
         )?;
         let mut dims = self.dims().to_vec();
         dims[dim] = indexes_len;
-        let op = if indexes.track_op() || self.track_op() {
+        let op = BackpropOp::new2(self, indexes, |t1, t2| Op::IndexSelect(t1, t2, dim));
-            Some(Op::IndexSelect(self.clone(), indexes.clone(), dim))
-        } else {
-            None
-        };
         Ok(from_storage(storage, dims, op, false))
     }
 
@@ -1404,11 +1330,7 @@ impl Tensor {
     pub fn transpose<D1: Dim, D2: Dim>(&self, dim1: D1, dim2: D2) -> Result<Tensor> {
         let dim1 = dim1.to_index(self.shape(), "transpose")?;
         let dim2 = dim2.to_index(self.shape(), "transpose")?;
-        let op = if self.track_op() {
+        let op = BackpropOp::new1(self, |t| Op::Transpose(t, dim1, dim2));
-            Some(Op::Transpose(self.clone(), dim1, dim2))
-        } else {
-            None
-        };
         let tensor_ = Tensor_ {
             id: TensorId::new(),
             storage: self.storage.clone(),
@@ -1434,11 +1356,7 @@ impl Tensor {
     /// Compared to clone, this copies the actual storage but may fail because of running out of
     /// memory.
     pub fn copy(&self) -> Result<Tensor> {
-        let op = if self.track_op() {
+        let op = BackpropOp::new1(self, Op::Copy);
-            Some(Op::Copy(self.clone()))
-        } else {
-            None
-        };
         let tensor_ = Tensor_ {
             id: TensorId::new(),
             storage: Arc::new(RwLock::new(self.storage().try_clone(self.layout())?)),
@@ -1458,7 +1376,7 @@ impl Tensor {
             id: TensorId::new(),
             storage: self.storage.clone(),
             layout: self.layout.clone(),
-            op: None,
+            op: BackpropOp::none(),
             is_variable: false,
             dtype: self.dtype,
             device: self.device.clone(),
@@ -1484,11 +1402,7 @@ impl Tensor {
                 }
                 (Storage::Cpu(storage), Device::Cpu) => Storage::Cpu(storage.clone()),
             };
-            let op = if self.track_op() {
+            let op = BackpropOp::new1(self, Op::ToDevice);
-                Some(Op::ToDevice(self.clone()))
-            } else {
-                None
-            };
             let tensor_ = Tensor_ {
                 id: TensorId::new(),
                 storage: Arc::new(RwLock::new(storage)),
@@ -1519,16 +1433,11 @@ impl Tensor {
     /// any value, the dimension `t_a` must be equal to `i_a` if `i_a` is different from 1. If
     /// `i_a` is equal to 1, any value can be used.
     pub fn broadcast_as<S: Into<Shape>>(&self, shape: S) -> Result<Self> {
-        let op = if self.track_op() {
-            Some(Op::Broadcast(self.clone()))
-        } else {
-            None
-        };
         let tensor_ = Tensor_ {
             id: TensorId::new(),
             storage: self.storage.clone(),
             layout: self.layout.broadcast_as(shape)?,
-            op,
+            op: BackpropOp::new1(self, Op::Broadcast),
             is_variable: false,
             dtype: self.dtype,
             device: self.device.clone(),
@@ -1557,11 +1466,7 @@ impl Tensor {
         } else {
             let shape = self.shape();
             let storage = self.storage().to_dtype(self.layout(), dtype)?;
-            let op = if self.track_op() {
+            let op = BackpropOp::new1(self, Op::ToDType);
-                Some(Op::ToDType(self.clone()))
-            } else {
-                None
-            };
             Ok(from_storage(storage, shape.clone(), op, false))
         }
     }
@@ -1576,11 +1481,7 @@ impl Tensor {
             let mut storage = self.device().zeros(shape, self.dtype())?;
             self.storage()
                 .copy_strided_src(&mut storage, 0, self.layout())?;
-            let op = if self.track_op() {
+            let op = BackpropOp::new1(self, Op::Copy);
-                Some(Op::Copy(self.clone()))
-            } else {
-                None
-            };
             Ok(from_storage(storage, shape.clone(), op, false))
         }
     }
@@ -1612,11 +1513,7 @@ impl Tensor {
             }
             .bt());
         }
-        let op = if self.track_op() {
+        let op = BackpropOp::new1(self, Op::Reshape);
-            Some(Op::Reshape(self.clone()))
-        } else {
-            None
-        };
         if self.is_contiguous() {
             let tensor_ = Tensor_ {
                 id: TensorId::new(),
@@ -1820,12 +1717,7 @@ impl Tensor {
             offsets.push(next_offset);
         }
         let shape = Shape::from(cat_dims);
-        let op = if args.iter().any(|arg| arg.as_ref().track_op()) {
+        let op = BackpropOp::new(args, |args| Op::Cat(args, 0));
-            let args: Vec<Tensor> = args.iter().map(|arg| arg.as_ref().clone()).collect();
-            Some(Op::Cat(args, 0))
-        } else {
-            None
-        };
         let mut storage = device.zeros(&shape, dtype)?;
         for (arg, &offset) in args.iter().zip(offsets.iter()) {
             let arg = arg.as_ref();
@@ -1865,11 +1757,7 @@ impl Tensor {
         let (storage, shape) = self
             .storage()
             .custom_op1(self.layout(), c.as_ref().as_ref())?;
-        let op = if self.track_op() {
+        let op = BackpropOp::new1(self, |s| Op::CustomOp1(s, c.clone()));
-            Some(Op::CustomOp1(self.clone(), c))
-        } else {
-            None
-        };
         Ok(from_storage(storage, shape, op, false))
     }
 
@@ -1885,11 +1773,7 @@ impl Tensor {
             rhs.layout(),
             c.as_ref().as_ref(),
         )?;
-        let op = if self.track_op() {
+        let op = BackpropOp::new2(self, rhs, |t1, t2| Op::CustomOp2(t1, t2, c.clone()));
-            Some(Op::CustomOp2(self.clone(), rhs.clone(), c))
-        } else {
-            None
-        };
         Ok(from_storage(storage, shape, op, false))
     }
 
@@ -1907,11 +1791,9 @@ impl Tensor {
             t3.layout(),
             c.as_ref().as_ref(),
         )?;
-        let op = if self.track_op() {
+        let op = BackpropOp::new3(self, t2, t3, |t1, t2, t3| {
-            Some(Op::CustomOp3(self.clone(), t2.clone(), t3.clone(), c))
+            Op::CustomOp3(t1, t2, t3, c.clone())
-        } else {
+        });
-            None
-        };
         Ok(from_storage(storage, shape, op, false))
     }