pytorch/torch/csrc/jit/codegen/fuser
2025-05-28 08:44:58 +00:00
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cpu [Environment Variable][7/N] Use thread-safe getenv functions (#140211) 2025-04-24 01:06:29 +00:00
cuda Remove outdated CUDA 11 conditions (#154313) 2025-05-28 08:44:58 +00:00
arg_spec.h Remove cppcoreguidelines-pro-type-member-init_fix suppression (#148638) 2025-04-02 01:33:20 +00:00
codegen.cpp
codegen.h
compiler.cpp [Environment Variable][7/N] Use thread-safe getenv functions (#140211) 2025-04-24 01:06:29 +00:00
compiler.h [Lint] Update clang-format to 19.1.4 (#153889) 2025-05-20 14:12:46 +00:00
executor.cpp
executor.h
fallback.cpp [1/N] Use internal linkage in torch/csrc C++ files. (#150930) 2025-04-11 02:19:31 +00:00
fallback.h
fused_kernel.h
interface.cpp [1/N] Use internal linkage in torch/csrc C++ files. (#150930) 2025-04-11 02:19:31 +00:00
interface.h
kernel_cache.cpp
kernel_cache.h
kernel_spec.h Fix clang-tidy warnings in torch/jit (#146963) 2025-02-15 03:36:59 +00:00
partition_desc.h
README.md
tensor_desc.h
tensor_info.h

PyTorch Fuser

The fuser accepts subgraphs wrapped in "fusion nodes" and tries to execute them by just-in-time (JIT) compiling kernels that run all the graph operations.

Code Organization

The fuser is designed hierarchically with device-independent logic eventually deferring to device-specific logic and implementation. The device-specific code is (mostly) found in each devices' subdirectory. The device-independent logic has six components:

  • The Interface (interface.h/cpp) has functions to register and run fusions, interrogate fusion functionality, and perform debugging.
  • The Compiler (compiler.h/cpp) performs "upfront" and "runtime" compilation. When fusions are registered, upfront compilation produces fallback code and and performs some shape inference. When a fusion is run, runtime compilation invokes code generation and the device-specific compilation logic.
  • The Code Generator (codegen.h/cpp) produces the string to be compiled on the device.
  • The Executor (executor.h/cpp) runs requested fusions. It performs shape inference, expands tensors as necessary, determines the device to run on, acquires a cached compiled kernel or requests the Compiler produce a new one, invokes device-specific code to launch the kernel and updates the stack.
  • The Fallback (fallback.h/cpp) runs subgraphs that can't be fused because shape inference didn't determine a common tensor size or the device the tensors are on doesn't support fusion.
  • The Kernel Specification Cache (kernel_cache.h/cpp) is a thread-safe cache holding the device-independent specifications produced during upfront compilation. These specifications each have their own thread-safe stores of compiled kernels that the Executor checks before requesting runtime compilation.

The device-specific components have logic for compiling and running code in FusedKernelCPU (cpu/fused_kernel.h/cpp) and FusedKernelCUDA (cuda/fused_kernel.h/cpp).