pytorch/torch/csrc/jit/codegen/cuda/arith.h
Christian Sarofeen 6d24f8fe21 Infrastructure for a new CUDA Fuser (#34785)
Summary:
**Summary:** This PR contains the infrastructure of a new CUDA fuser. This CUDA fuser is based on many of the same principles of TensorExpressions and Halide, however the implementation is ground up. The fusion pass itself is similar to the default CUDA fuser, however, it has undergone some refactoring and is using the new code generation infrastructure. For those who are interested in how the code generation in this PR works, I would recommend reviewing _test/cpp/jit/test_gpu_fusion.cpp_ as well as the long comment section at the beginning of _torch/csrc/jit/codegen/cuda/transform_replay.h_  One of the largest differences between our approach and that of TVM/Halide, is the concept of "TensorView". TensorView from a high level should be thought of similarly to how we think of working with Tensors in PyTorch. It's an N-D object which can undergo transformations that change its dimensionality. Dimensionality changes are done through the operations split/merge/reorder/computeAt. These transformations are similar to split/fuse/reorder/compute_at of TVM, they modify how a tensor is iterated over to generate GPU code. Interestingly, in our scheme these transformations are applied to tensors and only impact how that tensor is generated.

**Warning:** This PR is purposefully not feature complete with the current fuser. We wanted to separate out the infrastructure from the fusion capabilities. Once in, smaller incremental PRs will be submitted to expand capabilities of the fuser.

**Short term goals:**

Parity with current CUDA fuser (including performance):
- Dynamic shapes (no recompilation)
- Implicit handling of braodcast (broadcasted tensors are treated as tensors of the braodcasted size in the generated code)
- Dropout

**Mid-term goals:**

- Transposes fused with pointwise operations where transpose involves only 2 axes (across the fused operation).
- 1-D reductions fused with pointwise operations
Pull Request resolved: https://github.com/pytorch/pytorch/pull/34785

Reviewed By: ZolotukhinM

Differential Revision: D20650977

Pulled By: soumith

fbshipit-source-id: ee39c95a880e1b9822e874ed4cc180971572bf63
2020-04-02 09:22:42 -07:00

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1.5 KiB
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#pragma once
#include <torch/csrc/WindowsTorchApiMacro.h>
#include <torch/csrc/jit/codegen/cuda/ir_interface_nodes.h>
#include <torch/csrc/jit/codegen/cuda/type.h>
struct Val;
/*
* The operations defined in this header is intended as user facing functions.
* Generally users should not directly instantiate temporary TensorViews they
* should instead use the functions below which will automatically create IR
* nodes, and return a resulting TensorView of correctly tracked shapes.
*/
namespace torch {
namespace jit {
namespace fuser {
// Promotion logic between two values, returns a new val from resulting type
// promotion.
TORCH_CUDA_API Val* promoteNew(Val* v1, Val* v2);
// Insertion of casting op to dtype, returns new resulting val
TORCH_CUDA_API Val* castOp(DataType dtype, Val* v1);
// Perform unary op type and return the output
TORCH_CUDA_API Val* unaryOp(UnaryOpType type, Val* v1);
// Perform binary op type on v1 and v2 and return a type promoted output.
// Mod, CeilDiv, and LT are considered Int only output operations for now.
TORCH_CUDA_API Val* binaryOp(BinaryOpType type, Val* v1, Val* v2);
TORCH_CUDA_API Val* add(Val* v1, Val* v2);
TORCH_CUDA_API Val* sub(Val* v1, Val* v2);
TORCH_CUDA_API Val* mul(Val* v1, Val* v2);
TORCH_CUDA_API Val* div(Val* v1, Val* v2);
TORCH_CUDA_API Val* mod(Val* v1, Val* v2);
TORCH_CUDA_API Val* lt(Val* v1, Val* v2);
TORCH_CUDA_API Val* ceilDiv(Val* v1, Val* v2);
} // namespace fuser
} // namespace jit
} // namespace torch