feat: implement Hyperblock Fusion optimization #243
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- Add HyperblockDependencyAnalysis for detecting RAW/WAR/WAW dependencies - Implement OptimizeTaskGraphPass with hyperblock fusion and dead hyperblock elimination - Handle SSA outputs by creating new hyperblock with combined result types - Support non-adjacent hyperblock fusion by checking all (i,j) pairs - Allow RAW dependencies since operation ordering is preserved - Add hyperblock-fusion.mlir, nested-fusion.mlir, and fusion-with-outputs.mlir tests - Fix relu_kernel.mlir deterministic checks for upstream compatibility - Update CMakeLists.txt and TaskflowPasses registration
guosran
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Pull request overview
This PR implements a Hyperblock Fusion optimization pass for the Taskflow dialect to reduce task scheduling overhead and improve CGRA resource utilization. The implementation includes dependency analysis, hyperblock fusion within tasks, and dead hyperblock elimination.
Changes:
- Adds hyperblock dependency analysis (RAW/WAR/WAW detection) to enable safe fusion decisions
- Implements hyperblock fusion optimization that merges compatible hyperblocks with identical counter structures
- Adds three test files demonstrating fusion in different scenarios (basic, nested, with different operations)
- Updates test expectations in
relu_kernel.mlirto reflect changes from the optimization pass
Reviewed changes
Copilot reviewed 12 out of 12 changed files in this pull request and generated 7 comments.
Show a summary per file
| File | Description |
|---|---|
include/TaskflowDialect/Analysis/HyperblockDependencyAnalysis.h |
Defines dependency analysis API for detecting memory dependencies between hyperblocks |
lib/TaskflowDialect/Analysis/HyperblockDependencyAnalysis.cpp |
Implements RAW/WAR/WAW dependency detection and fusion safety checks |
lib/TaskflowDialect/Transforms/OptimizeTaskGraphPass.cpp |
Core optimization pass implementing hyperblock fusion and dead code elimination |
lib/TaskflowDialect/Analysis/CMakeLists.txt |
Adds analysis library to build system |
lib/TaskflowDialect/Transforms/CMakeLists.txt |
Links optimization pass with analysis library |
lib/TaskflowDialect/CMakeLists.txt |
Adds Analysis subdirectory to build |
include/TaskflowDialect/TaskflowPasses.td |
Defines pass options and documentation |
include/TaskflowDialect/TaskflowPasses.h |
Adds pass creation function declaration |
test/multi-cgra/taskflow/optimization/hyperblock-fusion.mlir |
Tests basic hyperblock fusion scenario (currently tests non-fusion case) |
test/multi-cgra/taskflow/optimization/nested-fusion.mlir |
Tests fusion of nested loops within same task |
test/multi-cgra/taskflow/optimization/fusion-with-outputs.mlir |
Tests fusion with different operation types |
test/e2e/relu/relu_kernel.mlir |
Updates test expectations after optimization pass changes |
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- Complete fuseHyperblocksInTask function comment - Add null check for getDialect() in estimateHyperblockResources - Fix posA/posB swap in HyperblockDependencyAnalysis::canFuse - Fix enableTaskFusion default to false in TaskflowPasses.td - Update hyperblock-fusion.mlir test description for accuracy - Revert relu_kernel.mlir to main branch version
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Pull request overview
Copilot reviewed 12 out of 12 changed files in this pull request and generated 1 comment.
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tancheng
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Jan 19, 2026
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plz use snake_case variable naming
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Hi~ @guosran, I think a better start for I will determine our affine controller design today and I will sync with you so that you can start. |
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Summary
Implements the
OptimizeTaskGraphpass for the Taskflow dialect, enabling Hyperblock Fusion optimization to reduce task scheduling overhead and improve CGRA resource utilization.Changes
New Files
Core Features
Dependency Analysis (HyperblockDependencyGraph)
Hyperblock Fusion (fuseHyperblocks)
Dead Hyperblock Elimination
Future Work