Remove legacy bindings by rdspring1 · Pull Request #5917 · NVIDIA/Fuser

rdspring1 · 2026-02-03T21:59:51Z

This PR removes the nvfuser python module, corresponding pybind11 CPP bindings, and any references from csrc. Version is bumped to 0.2.36.

github-actions · 2026-02-03T22:01:44Z

Review updated until commit d21881d

Description

Remove legacy nvfuser python module and bindings completely
Keep only nvfuser_direct module as the supported Python interface
Update build system to only compile nvfuser_direct extension
Fix LaunchParams initialization to avoid CUDA context creation on import
Update documentation and test references to use nvfuser_direct
Add NVF_API visibility annotations for proper symbol export

Changes walkthrough

Relevant files

Enhancement

7 files

version.txt `Bump version from 0.2.35 to 0.2.36`	+1/-1
CMakeLists.txt `Remove nvfuser python library build, keep only nvfuser_direct`	+3/-141
utils.py `Remove nvfuser._C extension handling, keep only nvfuser_direct`	+2/-7
check_symbol_visibility.sh `Remove nvfuser extension checks, keep only nvfuser_direct`	+1/-17
runtime.cpp `Use std::optional for LaunchParams to avoid CUDA context on import`	+13/-6
type.h `Add NVF_API visibility annotations for operator<< functions`	+2/-2
utils.h `Add NVF_API visibility annotation for getShardedLogicalAxis`	+2/-1

Documentation

5 files

autotune_inner_reduction.py `Add TODO comment to update script to use nvfuser_direct`	+2/-0
autotune_pointwise.py `Add TODO comment to update script to use nvfuser_direct`	+2/-0
autotune_matmul.py `Add TODO comment to update script to use nvfuser_direct`	+2/-0
profile_matmul.py `Add TODO comment to update script to use nvfuser_direct`	+1/-0
Serde.md `Update documentation about serialization being disabled`	+3/-1

Miscellaneous

1 files

fusion_segmenter.cpp `Update test reference URL in comment`	+1/-1

Additional files

36 files

options.cpp	+0/-2
options.h	+0/-2
fusion_kernel_runtime.cpp	+0/-12
fusion_record.cpp	+0/-952
fusion_record.h	+0/-124
README.md	+0/-210
__init__.py	+0/-649
__init__.pyi	+0/-4
benchmark_utils.py	+0/-160
__init__.py	+0/-9
__init__.py	+0/-13
normalization.py	+0/-725
nvfuser_version.py	+0/-69
pytorch_utils.py	+0/-190
fusion_cache.cpp	+0/-953
fusion_cache.h	+0/-320
fusion_definition.cpp	+0/-769
fusion_definition.h	+0/-389
fusion_record.h	+0/-3675
fusion_state.cpp	+0/-297
fusion_state.h	+0/-143
multidevice_bindings.cpp	+0/-103
python_bindings.cpp	+0/-4196
python_bindings.h	+0/-27
python_bindings_extension.cpp	+0/-18
schedule_bindings.cpp	+0/-517
segmentation.cpp	+0/-369
segmentation.h	+0/-246
translation.cpp	+0/-1484
translation.h	+0/-20
translation_utils.cpp	+0/-80
translation_utils.h	+0/-300
test_import.py	+0/-17
__init__.py	+0/-6
utils.py	+0/-358
env_options.yaml	+0/-12

PR Reviewer Guide

Here are some key observations to aid the review process:

🧪 PR contains tests
🔒 No security concerns identified
⚡ Recommended focus areas for review
API Signature Changes The KernelExecutor compile() and run() methods have been modified to make launch_constraints optional with default values. This is a breaking API change that could affect existing code using these methods. Ensure that all calling code has been updated accordingly and that this change is properly documented. py::arg("group_id") = 0) .def( "compile", [](KernelExecutor& self, Fusion* fusion, const py::iterable& args, std::optional<LaunchParams> launch_constraints, const CompileParams& compile_params, SchedulerType scheduler_type) { // launch_constraints is optional to avoid creating default // LaunchParams when importing shared library. self.compile( fusion, from_pyiterable(args), launch_constraints.value_or(LaunchParams()), compile_params, scheduler_type); }, Build Configuration Logic The build_extension method now only handles nvfuser_direct._C_DIRECT extension, removing the conditional logic for the legacy nvfuser._C extension. This appears correct given the PR goal, but verify that no other build configurations depend on the removed logic. def build_extension(self, ext): if ext.name == "nvfuser_direct._C_DIRECT": self.copy_library(ext, "libnvfuser_direct") self.copy_shared_library("libnvfuser_codegen.so") else: super().build_extension(ext) Symbol Visibility The getShardedLogicalAxis function declaration was moved and now has NVF_API visibility annotation. This change in symbol visibility could affect linking and should be verified to ensure proper symbol export. NVF_API int64_t getShardedLogicalAxis(const TensorView* tv, ParallelType parallel_type);

greptile-apps · 2026-02-03T22:03:38Z

Greptile Summary

This PR removes the legacy nvfuser Python module, its entire python_frontend C++ binding layer (~17,500 lines deleted), and related references from csrc. It retains the newer nvfuser_direct module as the sole Python API. Version is bumped to 0.2.36.

Key changes:

Deletes the entire python/nvfuser/ package and python/python_frontend/ directory
Removes the nvfuser CMake build target and associated build configuration
Removes csrc/serde/fusion_record.{cpp,h} which supported legacy serialization
Removes PythonDefinitionSegments and PythonFrontendDebug debug dump options from csrc/options.{h,cpp} and fusion_kernel_runtime.cpp
Removes legacy test utilities (tests/python/utils/) and import-conflict tests
Moves python_common sources (distributed_tensor, python_utils, translation_names) into the nvfuser_direct build target
Adds NVF_API visibility annotations to UnaryOpType, TernaryOpType operators and getShardedLogicalAxis needed by nvfuser_direct
Changes LaunchParams default argument in runtime.cpp to std::optional to avoid construction at import time
Cleans up tools/check_symbol_visibility.sh and tools/env-config/env_options.yaml

Remaining items to address:

doc/dev/python_scheduling/ scripts (autotune_utils.py, autotune_persistent.py, autotune_inner_reduction.py, autotune_matmul.py, autotune_pointwise.py, profile_matmul.py) still have unconditional from nvfuser import ... statements and will fail at runtime. TODOs were added to four of them but the imports were not updated.
python/utils.py still includes include/nvfuser/python_frontend/*.h in nvfuser_common_package_data, but those headers no longer exist.

Confidence Score: 4/5

This PR is a large but straightforward deletion with minor leftover references that need cleanup.
The core removal is clean and thorough — all legacy C++ bindings, Python modules, CMake targets, and debug options are consistently removed. The nvfuser_direct build correctly picks up the formerly shared python_common sources. The LaunchParams optional change is a sound approach. Score is 4 instead of 5 because several doc/dev scripts remain broken with stale nvfuser imports, and there's a stale package_data glob.
doc/dev/python_scheduling/ scripts (autotune_utils.py, autotune_persistent.py not in changeset) and python/utils.py (stale python_frontend package data glob)

Important Files Changed

Filename	Overview
CMakeLists.txt	Removes nvfuser legacy Python library build target and related cmake config; moves python_common sources into nvfuser_direct build. Clean removal.
csrc/multidevice/utils.h	Adds NVF_API visibility annotation to getShardedLogicalAxis, needed now that nvfuser_direct links against codegen directly.
csrc/options.h	Removes PythonDefinitionSegments and PythonFrontendDebug enum values from DebugDumpOption.
csrc/runtime/fusion_kernel_runtime.cpp	Removes includes and debug-dump code for PythonDefinitionSegments that used the now-removed python_frontend translation. Clean removal.
csrc/serde/Serde.md	Adds a note that serialization is disabled but the rest of the document still describes removed python_frontend code (FusionCache, RecordFunctor, Trie, etc.).
csrc/type.h	Adds NVF_API to UnaryOpType and TernaryOpType operator<< for symbol visibility in nvfuser_direct.
doc/dev/python_scheduling/autotune_inner_reduction.py	Adds TODO comment but still imports from removed nvfuser module - script will fail at runtime.
doc/dev/python_scheduling/autotune_matmul.py	Adds TODO comment but still imports from removed nvfuser module - script will fail at runtime.
doc/dev/python_scheduling/autotune_pointwise.py	Adds TODO comment but still imports from removed nvfuser module - script will fail at runtime.
doc/dev/python_scheduling/profile_matmul.py	Adds TODO comment but still imports from removed nvfuser module - script will fail at runtime.
python/python_direct/runtime.cpp	Changes LaunchParams default argument to std::optional to avoid creating default LaunchParams at import time. Clean workaround.
python/utils.py	Removes nvfuser._C extension module build; keeps nvfuser_direct._C_DIRECT only. Contains a stale include path for python_frontend headers in package_data.
tests/python/direct/test_import.py	Removes test_import_conflict_direct_then_nvfuser test that tested legacy nvfuser vs nvfuser_direct import conflict. Keeps test_import_correct for nvfuser_direct.
tools/check_symbol_visibility.sh	Removes all nvfuser extension symbol checking, keeping only nvfuser_direct. Clean removal.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    subgraph "Before (Removed)"
        A[python/nvfuser/ package] --> B[python_frontend/ C++ bindings]
        B --> C[libnvfuser.so]
        C --> D[libnvfuser_codegen.so]
        E[csrc/serde/fusion_record.cpp] --> B
    end
    subgraph "After (Retained)"
        F[python/nvfuser_direct/ package] --> G[python_direct/ C++ bindings]
        G --> H[libnvfuser_direct.so]
        H --> I[libnvfuser_codegen.so]
        J[python_common/ sources] --> H
    end
    style A fill:#f99,stroke:#c33
    style B fill:#f99,stroke:#c33
    style C fill:#f99,stroke:#c33
    style E fill:#f99,stroke:#c33
    style F fill:#9f9,stroke:#3c3
    style G fill:#9f9,stroke:#3c3
    style H fill:#9f9,stroke:#3c3
    style I fill:#9f9,stroke:#3c3
    style J fill:#9f9,stroke:#3c3

_{Last reviewed commit: d21881d}

greptile-apps

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greptile-apps · 2026-02-03T22:03:49Z

Additional Comments (2)

python/utils.py
stale reference to removed python_frontend directory

tools/env-config/env_options.yaml
stale entries for removed debug options python_definition_segments and python_frontend_debug should be removed

greptile-apps

_{8 files reviewed, 1 comment}

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greptile-apps · 2026-02-03T23:49:33Z

Additional Comments (1)

python/utils.py
outdated comment references nvfuser._C which was removed in this PR

    # "nvfuser_codegen" into "./nvfuser_direct/lib", and the former will be "nvfuser_direct._C_DIRECT".

greptile-apps

_{8 files reviewed, 1 comment}

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python/utils.py

greptile-apps

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greptile-apps · 2026-02-04T06:20:54Z

Additional Comments (7)

tests/python/utils/utils.py
The nvfuser module has been removed in this PR. Update to import from nvfuser_direct instead:

from nvfuser_direct import FusionCache, FusionDefinition, DataType, clone, Tensor

doc/dev/python_scheduling/autotune_utils.py
The nvfuser module has been removed. Update to import from nvfuser_direct:

from nvfuser_direct import FusionCache, FusionDefinition

doc/dev/python_scheduling/autotune_pointwise.py
Update to use nvfuser_direct instead of removed nvfuser module:

from nvfuser_direct import FusionDefinition, SchedulerType, DataType

doc/dev/python_scheduling/autotune_inner_reduction.py
Update to use nvfuser_direct:

from nvfuser_direct import FusionDefinition, SchedulerType, DataType, ParallelType

_{Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!}

doc/dev/python_scheduling/autotune_persistent.py
Update imports to use nvfuser_direct:

from nvfuser_direct import FusionCache, FusionDefinition, SchedulerType, DataType
from nvfuser_direct.pytorch_utils import torch_dtype_to_nvfuser_dtype

_{Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!}

doc/dev/python_scheduling/autotune_matmul.py
Update to use nvfuser_direct:

from nvfuser_direct import FusionDefinition, SchedulerType

_{Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!}

doc/dev/python_scheduling/profile_matmul.py
Update imports to use nvfuser_direct instead of removed nvfuser module

greptile-apps

_{8 files reviewed, no comments}

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greptile-apps

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greptile-apps · 2026-02-04T19:28:45Z

doc/dev/python_scheduling/autotune_inner_reduction.py

+
+# TODO Update script to use nvfuser_direct module


TODO added but imports still reference removed nvfuser module - script will fail

Suggested change

# TODO Update script to use nvfuser_direct module

# TODO Update script to use nvfuser_direct module

from nvfuser_direct import FusionDefinition, SchedulerType, DataType, ParallelType

greptile-apps · 2026-02-04T19:28:46Z

doc/dev/python_scheduling/autotune_matmul.py

+
+# TODO Update script to use nvfuser_direct module


TODO added but imports still reference removed nvfuser module - script will fail

Suggested change

# TODO Update script to use nvfuser_direct module

# TODO Update script to use nvfuser_direct module

from nvfuser_direct import FusionDefinition, SchedulerType

greptile-apps · 2026-02-04T19:28:47Z

doc/dev/python_scheduling/autotune_pointwise.py

 import math
+


TODO added but imports still reference removed nvfuser module - script will fail

Suggested change

import math

# TODO Update script to use nvfuser_direct module

from nvfuser_direct import FusionDefinition, SchedulerType, DataType

greptile-apps · 2026-02-04T19:28:53Z

Additional Comments (3)

doc/dev/python_scheduling/autotune_utils.py
imports from removed nvfuser module will fail at runtime

from nvfuser_direct import FusionCache, FusionDefinition

doc/dev/python_scheduling/autotune_persistent.py
imports from removed nvfuser module will fail at runtime

from nvfuser_direct import FusionCache, FusionDefinition, SchedulerType, DataType
from nvfuser_direct.pytorch_utils import torch_dtype_to_nvfuser_dtype

doc/dev/python_scheduling/profile_matmul.py
TODO added but imports still reference removed nvfuser module - script will fail. All imports need updating to nvfuser_direct

greptile-apps

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greptile-apps · 2026-02-04T23:38:37Z

doc/dev/python_scheduling/autotune_inner_reduction.py

 import itertools
+
+# TODO Update script to use nvfuser_direct module
 from nvfuser import FusionDefinition, SchedulerType, DataType, ParallelType


Script imports from removed nvfuser module and will fail at runtime

Suggested change

from nvfuser import FusionDefinition, SchedulerType, DataType, ParallelType

from nvfuser_direct import FusionDefinition, SchedulerType, DataType, ParallelType

greptile-apps · 2026-02-04T23:38:41Z

doc/dev/python_scheduling/autotune_pointwise.py

@@ -6,6 +6,8 @@
 import torch
 import itertools
 import math


Script imports from removed nvfuser module and will fail at runtime

greptile-apps · 2026-02-04T23:38:46Z

Additional Comments (2)

doc/dev/python_scheduling/autotune_matmul.py
Script imports from removed nvfuser module and will fail at runtime

from nvfuser_direct import (
    FusionDefinition,
    SchedulerType,
    ClusterDims,
    MatMulTileOptions,
    GemmTile,
    MmaMacroEncode,
    MmaMacroArch,
    MatmulTileRasterizationOrder,

doc/dev/python_scheduling/profile_matmul.py
Script imports from removed nvfuser module and will fail at runtime

from nvfuser_direct import (
    FusionDefinition,
    SchedulerType,
    ClusterDims,
    MatMulTileOptions,
    GemmTile,
    MmaMacroEncode,
    MmaMacroArch,
    MatmulTileRasterizationOrder,
    MatmulCircularBufferingStrategy,
)

greptile-apps

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greptile-apps · 2026-02-18T17:12:01Z

tools/check_symbol_visibility.sh

Stale reference to removed nvfuser extension

This line references nvfuser_undefined_symbols.txt, but that file is never generated since the check_extension_symbols "$NVFUSER_EXT" "nvfuser" call was removed. Only nvfuser_direct_undefined_symbols.txt is produced now. This should be removed.

Suggested change

echo "- nvfuser_undefined_symbols.txt: Undefined symbols from nvfuser extension"

greptile-apps · 2026-02-18T17:12:02Z

csrc/serde/Serde.md


 # NvFuser Serialization

+## Serialization is disabled because legacy bindings are removed.


Stale documentation referencing removed code

The note on line 9 says serialization is "disabled," but the rest of the document (lines 14–421) still extensively describes FusionCache, RecordFunctor, the Trie structure, and the serde testing process — all of which rely on the now-removed python_frontend code. Consider either removing or archiving the bulk of this file, or at least adding a more prominent deprecation notice explaining which parts are still valid vs. obsolete.

_{Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!}

* LaunchParams is constructed when nvfuser_direct is loaded. * It uses at::cuda::getCurrentDeviceProperties(), which initializes Cuda context.

rdspring1 · 2026-02-18T21:18:22Z

!test --dev

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greptile-apps · 2026-02-18T21:22:51Z

Additional Comments (1)

python/utils.py
Stale package_data glob for removed directory

This glob pattern references include/nvfuser/python_frontend/*.h, but the entire python_frontend directory and its headers have been removed in this PR. The CMakeLists.txt no longer installs these headers either, so this glob will match nothing. It should be removed to keep the packaging config accurate.

rdspring1 added the Direct Bindings Python extension with direct mapping to NvFuser CPP objects. label Feb 3, 2026

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rdspring1 force-pushed the remove_legacy_bindings branch from 7d0a9ba to 904ab90 Compare February 4, 2026 05:13

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rdspring1 force-pushed the remove_legacy_bindings branch from 21cb6bd to 5107f26 Compare February 4, 2026 19:24

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rdspring1 added 2 commits February 18, 2026 09:05

Remove legacy bindings

d23b9e4

bump version

7ffc944

rdspring1 force-pushed the remove_legacy_bindings branch from aa333da to da9c5e0 Compare February 18, 2026 17:06

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rdspring1 added 2 commits February 18, 2026 13:17

Update tools/check_symbol_visibility.sh

fc7615c

Use std::optional instead of direct default argument for LaunchParams

d21881d

* LaunchParams is constructed when nvfuser_direct is loaded. * It uses at::cuda::getCurrentDeviceProperties(), which initializes Cuda context.

rdspring1 force-pushed the remove_legacy_bindings branch from da9c5e0 to d21881d Compare February 18, 2026 21:18

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View reviewed changes

	import math
	# TODO Update script to use nvfuser_direct module
	from nvfuser_direct import FusionDefinition, SchedulerType, DataType

	from nvfuser import FusionDefinition, SchedulerType, DataType, ParallelType
	from nvfuser_direct import FusionDefinition, SchedulerType, DataType, ParallelType


		# NvFuser Serialization

		## Serialization is disabled because legacy bindings are removed.

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Greptile Summary

Confidence Score: 4/5

Important Files Changed

Flowchart

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