GitLab

This commit refines the Fragment creation process in the InferLayout method of ParallelOpNode. It removes the unnecessary forward_index array and utilizes default fragment indexing for consistency with other operations. Additionally, it binds the thread range to enhance comparability across different operations.

* [Refactor] Enhance CopyNode's IterVar Creation and Range Handling

This commit refines the `MakeIterVars` method in `CopyNode` to select base ranges based on memory scope levels, ensuring that the chosen ranges are not smaller than the original source ranges. Additionally, it updates the Python `copy` function to clarify range handling, including broadcasting logic and extent alignment. These changes improve the robustness and clarity of the copy operation's implementation.

* test fix

* feat: add fp8 variants; add placeholder for fp6/fp4 in meta

support ld with pack for fp32 dtype

add dump

add tempalte expand

remove unused dtype and change to rebased apis

* fix: when atom-m!=128, enable_ws

* fix: typo in tcgen05 meta; dispatch in gemm sm100

* Refactor GEMM and Reduce operations by moving NormalizeToBufferRegion and MakeAccessPtrFromRegion to utils.{h,cc} for better code organization and reuse.

* lint fix

* Refactor region handling by removing the RegionOp and updating NormalizeToBufferRegion to only accept BufferLoad and BufferRegion. This change improves code organization and simplifies the handling of memory regions across various operations.

* fix

* Refactor memory region handling by introducing `tl.region` calls across various operations, including GEMM and fill functions. This change enhances the consistency of region management and improves code organization by utilizing utility functions for buffer region conversions.

* fix

* fix

* test fix

* lint fix

* Refactor GEMM operations to improve memory region handling by replacing `mbarPtr_` with `mbarRegion_` and updating related logic in both C++ and Python implementations. This change enhances the clarity and consistency of buffer region management.

* fix

* lint fix

* fix

* fix

* test fix

* lint fix

* lint fix

* minor fix

* fix

---------
Co-authored-by: Zhiwen Mo <zm125@ic.ac.uk>

* [Fix] fix copy from or to local buffer (#1304)

* fix lint error

* minor fix testing script

* Refactor GEMM and Reduce operations by moving NormalizeToBufferRegion and MakeAccessPtrFromRegion to utils.{h,cc} for better code organization and reuse.

* lint fix

* [BugFix] Use BufferRegion in tl.cumsum to infer buffer shape

* remove debug lines

* remove rubbish

* Fix decorator syntax for atomic_different_memory_orders_program

---------
Co-authored-by: Lei Wang <34334180+LeiWang1999@users.noreply.github.com>

* [Feat] Support warp reduce

* lint

* add test

* lint

This reverts commit 0d101c11

.
Co-authored-by: Zhiwen Mo <zm125@ic.ac.uk>

* [Refactor] Update Vectorization Functions to Accept Analyzer Parameter

- Modified `VectorizeLoop` and related functions to accept an `arith::Analyzer` parameter, enhancing their capability to perform analysis during vectorization.
- Updated multiple instances in `copy.cc`, `fill.cc`, `parallel.cc`, and layout inference files to utilize the new analyzer parameter for improved performance and correctness.
- Ensured consistency across vectorization logic by integrating the analyzer into existing workflows, facilitating better optimization opportunities.

* [Fix] Corrected PostOrderVisit call in loop_vectorize.cc

- Updated the PostOrderVisit function to analyze the body of the loop node instead of the node itself, ensuring proper handling of nested loops during vectorization analysis.

* fix

* lint fix

* fix

support ld with pack for fp32 dtype

add dump

add tempalte expand

remove unused dtype and change to rebased apis

* [Refactor] Update buffer handling in copy and atomic operations

* Refactored the `copy` and `atomic_add` functions to use element-wise minimum for defining copy extents, ensuring correct handling of overlapping regions.
* Updated utility functions to create `BufferLoad` instances with explicit extents, improving memory management and clarity.
* Removed unused imports from `atomic.py` and `copy.py` to streamline the codebase.
* Adjusted logging in `copy.cc` to provide clearer warnings for fallback scenarios in bulk copy operations.

* Remove obsolete .git_commit.txt file

* Add unit test for dynamic copy extent handling in TileLang

* Introduced a new test file `test_tilelang_issue_1237.py` to verify that the `T.copy` function correctly manages dynamic extents during primitive function building.
* The test reproduces a specific issue related to dynamic slice lengths and static buffer sizes, ensuring robustness in the handling of such scenarios.
* The test does not require execution of the kernel, as building the primitive function is sufficient to validate the fix.

* lint fix

* fix

* Revert "fix"

This reverts commit 828b4c1e4de76a7d11e4d4092927303fbbe00097.

* Update TVM submodule and refactor atomic and copy functions

* Updated the TVM submodule to a dirty state.
* Refactored `atomic_add` and `copy` functions to pass extents explicitly to the `_to_region` helper, improving clarity and correctness in handling buffer regions.
* Commented out the main execution call in the test example for `cast` and added a new function call to better demonstrate the example usage.

* Enhance extent handling in atomic and copy functions

* Introduced `legalize_pairwise_extents` utility to align and broadcast extent lists for `atomic_add` and `copy` functions, ensuring compatibility and correctness in buffer operations.
* Updated both functions to utilize the new utility, improving clarity and robustness in handling dynamic and static extents.
* Added comments to clarify the extent handling logic.

* Enhance `legalize_pairwise_extents` function with early-exit rule

* Added an early-exit condition to the `legalize_pairwise_extents` function to return original extents if the number of non-1 dimensions in both source and destination extents is equal, improving performance by avoiding unnecessary adjustments.
* Updated the function's documentation to clarify the new behavior and maintain clarity in the extent handling logic.

* lint fix

* Update layout handling and introduce reshape functionality

- Updated the `LayoutNode` class to include a new `Reshape` method, allowing for dynamic reshaping of layouts based on input shapes.
- Enhanced the `OutputShape` method to provide better handling of cases where the analyzer cannot form an `IntervalSet`, implementing fallback mechanisms to ensure safe extents.
- Refactored the `ReduceOpNode` to utilize `BufferRegion` for improved memory handling during reduction operations.
- Added tests for reshaping functionality and layout transformations to ensure correctness and performance in various scenarios.

* lint fix

* Revert tvm submodule pointer to 1815c3e0b6ec4ead36370bbd1562025d8529017c; keep src unchanged

* Update tvm submodule to commit f0bbd3bf741413c35c389ba5dedd5be206000ad1

* Update tvm submodule to commit f0bbd3bf741413c35c389ba5dedd5be206000ad1

* remove useless prove

* remove comment

---------
Co-authored-by: tilelang-bot <bot@tilelang>

* Add kernel selection option for GEMM v1 in environment settings

- Introduced `TILELANG_USE_GEMM_V1` environment variable to control the selection of GEMM version.
- Added `use_gemm_v1` method in the `Environment` class to determine if GEMM v1 should be used based on the environment variable.
- Updated GEMM function assignment to default to v2, allowing for v1 to be forced via the new environment variable.

* bug fix

* Add kernel selection option for GEMM in environment settings

- Introduced `TILELANG_USE_GEMM_V1` environment variable to allow users to select between GEMM v1 and v2 implementations.
- Updated `gemm` function to default to v2 but switch to v1 if the environment variable is set to a truthy value.
- Added a method `use_gemm_v1` in the `Environment` class to facilitate this selection based on the environment variable.

* Refactor GEMM macro generator to use BufferRegion instead of Buffer

- Updated `wgmma` and `wgmma_rs` methods in `TensorCoreIntrinEmitter` to accept `BufferRegion` parameters instead of `Buffer`.
- Adjusted related calls in `GemmWGMMA` to ensure compatibility with the new parameter types.
- Simplified buffer access logic for better clarity and maintainability.

* Refactor GEMM functions to utilize BufferRegion for improved memory handling

- Updated `run_gemm`, `run_gemm_rs`, `run_gemm_sr`, and `run_gemm_rr` functions to set `num_stages` based on block dimensions, enhancing performance for larger matrices.
- Simplified calls to GEMM functions by removing redundant parameters and ensuring compatibility with BufferRegion.
- Introduced utility functions for converting between Buffer, BufferLoad, and BufferRegion, improving code clarity and maintainability.
- Enhanced error handling for full region checks in GEMM operations to ensure correctness in memory access.

* Refactor GEMM code for improved readability and consistency

- Cleaned up formatting and spacing in GEMM-related files for better readability.
- Standardized comments and code structure across various GEMM functions and macros.
- Enhanced error messages for clarity in buffer region checks.
- Removed redundant lines and improved overall code maintainability.

* Update GEMM correctness evaluation and macro generator for improved functionality

- Modified `N_VALUES` in `correctness_evaluation_sm70.py` to include only relevant sizes for tests.
- Updated test function call in `correctness_evaluation.py` to use `test_gemm_false_true` for better accuracy in testing.
- Refactored buffer handling in `mma_sm70_macro_generator.py` to improve clarity and consistency in shared buffer access.
- Enhanced `gemm_mma_sm70.py` to ensure full region checks for input and output buffers, improving correctness in GEMM operations.

* Refactor GEMM and intrinsic files for improved clarity and functionality

- Removed unused variable `A_stride_last` in `mma_sm70_macro_generator.py` to streamline code.
- Adjusted function signature formatting in `swizzle.py` for better readability.
- Restored the return of `GemmWGMMA` in `__init__.py` for correct GEMM instantiation.
- Removed unused variable `B_buf` in `gemm_mma_sm70.py` to enhance code cleanliness.
- Improved function signature formatting in `language.py` for consistency.

* Enhance GEMM and MMA functionality for FP64 support

- Refactored `GemmNode` to streamline the decision-making process for GEMM instruction selection.
- Added support for FP64 inputs in the MMA dispatcher, enabling new tensor operations.
- Introduced a new layout function for FP64 in `mma_layout.py` to facilitate shared memory storage.
- Updated `TensorCoreIntrinEmitter` to handle FP64 data types, including adjustments for micro tile dimensions and loading mechanisms.
- Enhanced utility functions to accommodate FP64 index mapping for shared memory operations.

* lint fix

* Refactor GEMM correctness evaluation and shared memory alignment handling

- Reverted the GEMM function call in `correctness_evaluation.py` to the original implementation for consistency.
- Added a helper function in `merge_shared_memory_allocations.cc` to streamline the marking of shared variables under alignment scope.
- Enhanced the `VisitExpr_` methods to ensure proper handling of shared memory alignment for `BufferLoadNode` and `VarNode` types.
- Cleaned up commented-out test code in `correctness_evaluation.py` for better readability.

* Enhance GEMM and MMA implementations with region-based memory handling

- Updated GEMM and MMA classes to utilize BufferRegion for input and output buffers, improving memory management and supporting strided GEMM operations.
- Added checks to ensure full region compliance for input buffers, enhancing correctness in matrix multiplication.
- Implemented clear accumulation functionality to reset output buffers before accumulation, ensuring accurate results in GEMM operations.

* Refactor test_tilelang_example_deepseek_v32.py to improve import structure and function calls

- Updated import statements to directly reference modules instead of individual test functions, enhancing clarity.
- Modified function calls to use the new module structure for better organization and maintainability in testing examples.

* Enhance OnArrayDeclaration method to handle repeated buffer declarations

- Updated the OnArrayDeclaration method to merge metadata for buffers that may appear in multiple Allocate statements, improving robustness against upstream transformations.
- Added logic to prefer concrete element data types and record extents when previously unknown, enhancing the handling of buffer declarations.

* Add abbreviation for bfloat16 data type in mfma_macro_generator.py

- Introduced a new abbreviation "bf16" for the bfloat16 data type in the mfma_macro_generator.py file, enhancing clarity and consistency in data type representation.

* Refactor CodeGenTileLangHIP to enhance dtype handling and mfma call generation

- Introduced a mapping function to normalize input data types to their corresponding scalar types, improving compatibility with MfmaTraits.
- Updated the mfma call generation to utilize the new mapping, streamlining the code and enhancing clarity.
- Removed outdated dtype mapping and replaced it with a more flexible approach to support additional data types like FP8.

* lint fix

* Enhance backend configuration in CMakeLists.txt and improve dtype handling in CodeGenTileLangHIP

- Introduced a macro to define backend options for CUDA, ROCM, and Metal, allowing user overrides and caching of settings.
- Updated logic to track user-selected backends and conditionally enable defaults based on environment variables.
- Refactored dtype handling in CodeGenTileLangHIP to streamline mfma call generation and improve clarity.
- Added support for bfloat16 in the mfma_macro_generator.py, enhancing data type representation consistency.

* Update bfloat16 handling in CodeGenTileLangHIP and mfma_macro_generator.py

- Changed the representation of bfloat16 in CodeGenTileLangHIP from "bfloat16x4" to "bfloat16x4_vec" for improved clarity.
- Adjusted the mfma_suffix generation in mfma_macro_generator.py to remove the underscore before "bf16", aligning with HIP intrinsic requirements.

* Change logging level from WARNING to DLOG in LegalizeNegativeIndex for non-negative index checks to reduce log verbosity.

* Refactor attention sink examples to simplify index calculations

- Updated index handling in `example_gqa_sink_bwd_bhsd.py` and `example_mha_sink_bwd_bhsd.py` to eliminate unnecessary local allocations and streamline logic for determining start and end indices.
- Improved readability by using direct calculations instead of local variables for index bounds in pipelined loops.

* Refactor attention sink examples to streamline index calculations

- Simplified index handling in `example_gqa_sink_bwd_bhsd.py`, `example_gqa_sink_fwd_bhsd_wgmma_pipelined.py`, `example_mha_sink_bwd_bhsd.py`, `example_mha_sink_fwd_bhsd_wgmma_pipelined.py`, and `example_mha_sink_fwd_bhsd.py` by removing unnecessary local allocations for start and end indices.
- Enhanced readability by directly calculating index bounds for pipelined loops, improving overall code clarity.

* lint fix

* bugfix

* Refactor reduce operation handling in CUDA and Python

- Removed outdated shared memory reduction logic from `reduce.cc`.
- Introduced fragment allocation and improved buffer handling in `reduce.py` to support shared and fragment scopes.
- Updated CUDA header to define a wider accumulator type for better numerical accuracy.
- Enhanced error handling for buffer scope validation in the reduction process.

* Fix ReduceOpNode to correctly compute AbsMax by using absolute values of inputs

* Enhance unit loop handling by refining annotation checks

- Updated the condition for identifying effectively empty annotations in unit loops to include cases where only the `pragma_unroll_explicit` hint is present.
- Introduced a new method, `IsEffectivelyEmptyAnnotation`, to encapsulate this logic, improving code clarity and maintainability.

* clean clode

* fix

* Fix logging level in LayoutNode::InverseWithLevel method from WARNING to DLOG for symbolic layout fallback.

* lint fix

---------
Co-authored-by: Zhiwen Mo <zm125@ic.ac.uk>

* [Enhancement] Add thread count validation for ReduceOp fragment layout inference

* Introduced a check to ensure that the thread count is divisible by the replicate extent during layout inference in ReduceOpNode. This validation prevents layout inference failures and provides detailed error messages to guide users in resolving issues related to thread block sizes and fragment layouts.
* Updated tests to remove unsupported configurations that could lead to layout inference errors, ensuring more robust testing scenarios.

* lint fix

* [Refactor] Update ReduceOpNode to use absolute values in Max computation and remove unused shared memory reduction logic

* Changed Max computation for AbsMax type to use absolute values of lhs and rhs.
* Removed unused shared memory reduction logic and related checks for buffer dimensions and thread extents, simplifying the Lower method.
* Added a fatal log for unsupported buffer scope reductions.

* reduce fix

* [Fix] Update type check for eval value in Builder class

* Changed the type check for eval values to raise a TypeError for unsupported types, specifically excluding instances of tvm.tir.Buffer. This improves error handling and clarity in the Builder class.

* [Enhancement] Improve iterator handling in layout utilities and parallel operations

* Added a new function, DivideUnusedIterators, to detect per-iterator gaps in fused index expressions, enhancing the accuracy of unused iterator detection.
* Updated CompleteBufferFragment to prefer direct inversion for bijective index mappings and introduced a fallback mechanism for non-bijective cases, improving layout inversion robustness.
* Added a new test for layout inference in fused kernels to ensure correct compilation and execution without layout inversion failures.

* lint fix

* [Feature] Add support for SM70 tensor core MMA instructions

- Introduced new intrinsic `ptx_mma_sm70` for Volta GPUs, enabling m16n16k4 shape with FP16 inputs and FP16/FP32 accumulation.
- Added `GemmMMASm70` class for handling GEMM operations specific to SM70 architecture.
- Implemented layout functions for Volta swizzled layouts and updated existing GEMM layout inference logic.
- Updated `requirements-dev.txt` to include `apache-tvm-ffi` dependency.
- Added correctness evaluation script for testing GEMM operations on SM70.

* [Refactor] Update formatting and installation commands in scripts

- Modified `format.sh` to install `pre-commit` and `clang-tidy` with the `--user` flag for user-specific installations.
- Improved readability in `correctness_evaluation_sm70.py` by adjusting the formatting of pytest parameters.
- Cleaned up spacing and formatting in various C++ source files for better consistency and readability.
- Removed unnecessary comments and improved layout function definitions in `mma_sm70_layout.py` and `mma_sm70_macro_generator.py` for clarity.
- Ensured consistent formatting in layout initialization and swizzle functions.

* typo fix

* Update dependency version for apache-tvm-ffi in pyproject.toml to fix CI

* [Math] Add `tl.infinity` operation and update Python interface for infinity handling

- Implemented `infinity_op` in C++ to return infinity values for supported data types.
- Registered new operation `tl.infinity` with appropriate attributes.
- Updated Python interface to call the new `tl.infinity` operation instead of the previous method.

* Add unit tests for `tl.infinity` operation in TileLang

- Introduced a new test file `test_tilelang_language_infinity.py` to validate the behavior of the `tl.infinity` operation across multiple data types (float16, bfloat16, float32, float64).
- Implemented a kernel to fill a tensor with infinity values and asserted the correctness of the output against PyTorch's `torch.inf`.

* lint

---------
Co-authored-by: Zhiwen Mo <zm125@ic.ac.uk>

* [Feature] Enhance fill operation to support various buffer types

- Added support for `BufferLoad` in the `fill` function to handle different buffer types.
- Updated `Fill` class to process region descriptors and buffer regions, improving flexibility in buffer handling.
- Introduced checks for static bounds in region definitions to ensure safety during operations.
- Refactored loop induction variable handling in `FillNode` to accommodate sliced regions.

* lint fix

* fix

* lint fix

* fix

* lint fix

* fix

* upd

* remove debug print

* pipeline fix

* use the correct buffer access scope

* rs support

* warp warpgroup_fence_operand

* fix

* fp8 dtype ptx enhance

* mma fix

* TCGEN05 Interface

* tcgen05 support

* rebase

* update

* Enhance TCGEN05 support by adding new intrinsic operations and descriptors. Introduced `ptx_tcgen05_mma_ts` for tensor-memory to shared-memory instructions and `tcgen05_mma_arrive` for signaling barrier completion. Updated existing descriptors and code generation logic to accommodate these changes, ensuring compatibility with new instruction sets. Refactored related allocation functions and improved handling of shared memory descriptors.

* lint fix

* Refactor buffer reference handling in CUDA code generation and update test execution in tilelang. Ensure default annotations for unrolling are set correctly in TIR IR module.

* wgmma fix

---------
Co-authored-by: Zhiwen Mo <zm125@ic.ac.uk>

* 3rdparty tvm bump

* bump tvm into v0.22.0

* lint fix

* rebase tvm

* Update submodule tvm to latest commit 3085bc4

* Refactor: Update configuration retrieval in CopyNode and adjust test registration in tilelang

* test fix

* add requirement

* atomic_fix

* atomic_fix

* phaseout py39

* optimize

* optimize

* lint fix

* do not clean cache

* do not clean cache

* [Minor] Minor update for Python versions and dependencies

* [Lint] fix lint for py39

* [Lint] fix lint for ROCm

* [Build][CI] Sync CI changes from upstream/sdist

* [Lint] fix lint for ROCm

* [Build][CI] Update `repair-wheel-command`

* [Minor] update abi3audit result format

* [Lint] fix lint for ROCm

* [BugFix] fix build

* [Lint] fix lint for ROCm

* [BugFix] set rpath for libtvm and libtvm_runtime

* [Deps] pin apache-tvm-ffi version

* [Build] set Python 3.9 Limited API for Cython target

* [Build] set Python 3.9 Limited API for Cython target

* [Deps] Restore Python 3.8 support

* [Build] use `apache-tvm-ffi`'s `libtvm_ffi`

* [BugFix] use `;` as delimiter for RPATH on macOS

* [BugFix] use `--ignore-missing-dependencies` for `delocate-wheel`

* [Build] support `sccache` if available

* [Build] add CIBW import test

* [Build][CI] enable ccache for CIBW on Linux

* [BugFix] set rpath for libtvm and libtvm_runtime

* Revert "[Build][CI] enable ccache for CIBW on Linux"

This reverts commit cd9ab57bb5ddd2572c60bcbbebde81480a658fd3.

* [CI] fix perfbench bot

* [BugFix] use Python 3.9 to build wheel

* [Minor] update perfbench bot envs

* [BugFix] fix CIBW environment on Linux

* [CI] skip import test on CentOS 7

* [CI] use Python urllib to download file instead of Wget

---------
Co-authored-by: Xuehai Pan <XuehaiPan@pku.edu.cn>

* update

* Update codegen_cuda.cc

* [Enhancement] Add missing  primitive after mbarrier init

* lint

* [Refactor] Improve scalar handling in CopyNode and update loop partition dtype logic

* Refactored CopyNode::MakeSIMTLoop to handle scalar cases more efficiently by moving the scalar check to the end of the function.
* Updated loop_partition.cc to set a default DataType for thread and vector extents, ensuring compatibility when loop_vars_ is empty.

* lint fix

* remove debug print

* [Lint] Retire `format.sh` and add `clang-tidy` to GHA workflow

* chore: update clang-tidy settings

* chore: upgrade clang-format and clang-tidy version

* lint: resolve clang-tidy errors

* [Maint] restore format.sh

* [CI] pre-commit autoupdate

* [Minor] fix `command -v` usage

* - carry existing local-var initializer map into OpaqueBlockLower, reattach it to
    generated Allocates and the PrimFunc attrs
  - thread the map through FlattenBuffer and StorageRewrite so flattened/merged
    allocations keep their tl.local_var_init annotations
  - teach annotation handling to accept scalar initializers, resolve buffers, and merge
    with existing stat

* lint fix

* enhance

* lint fix

* lint fix

* • Enable configurable StorageRewrite inplace detection

  - Add kStorageRewriteDetectInplace constant and register the flag with PassContext so C++ code no longer hard-codes the key.
  - Wire StorageRewrite to include TileLang builtin constants and honor the new config toggle when deciding inplace reuse.
  - Document the flag across Python surfaces (PassConfigKey, JIT/autotuner docs) with usage guidance and simplified IR examples.

* lint fix

* add test

* lint fix

* [BugFix] Add memory order argument for non-vectorized atomic add

* [Lint]

* [BugFix] Memory order

* [Lint]

* [BugFix] Argument in cuda template

* [Lint]

* Support reduce ss

* lint fix

* test fix

* lint fix

* [Feature] Support Reduce operators for bitwise and/or/xor

* [Lint]

* [Refactor] Refactor Pass  to support recursive load/store rewrite

* lint

* recursive collect conds for call_extern

* fix name

* [Lint]: [pre-commit.ci] auto fixes [...]

* lint

* [Lint]: [pre-commit.ci] auto fixes [...]

* lint

* [Lint]: [pre-commit.ci] auto fixes [...]

* address comment

* rename pad_value to safe_value

* lint

* add oob store test

* [Lint]: [pre-commit.ci] auto fixes [...]

* fix

* fix

---------
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

* [Enhancement] Improve layout inference for local buffer handling in parallel operations

* Added logic to check if a loop only manipulates "local" buffers, which affects thread binding decisions.
* Updated the condition for determining parallel loop execution to account for local buffer stores.
* Cleaned up comments for clarity and future considerations.

* [Refactor] Clean up parallel loop condition formatting in layout inference

* Reformatted the condition for determining parallel loop execution for better readability.
* Maintained existing logic while enhancing code clarity for future modifications.

---------
Co-authored-by: Zhiwen Mo <zm125@ic.ac.uk>

* update

* format

* rabbit

* Expose CUDA warp/lane intrinsics in TileLang frontend

* generalize warp indexing intrinsics and add coverage

* [Lint]: [pre-commit.ci] auto fixes [...]

---------
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

* keep >> instead of /

* re think replicate

* lint fix

* handle const int buffers

* rep fix

---------
Co-authored-by: Zhiwen Mo <zm125@ic.ac.uk>