[PATCH] D131606: [Loop Fusion] Sink/hoist memory instructions between loop fusion candidates

[Aaron K via Phabricator via llvm-commits]

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Currently, instructions in the preheader of the second of two fusion candidates are sunk and hoisted whenever possible, to try to allow the loops to fuse. Memory instructions are skipped, and are never sunk or hoisted. This change adds memory instructions for sinking/hoisting consideration.

This change uses DependenceAnalysis to check if a mem inst in the preheader of FC1 depends on an instruction in FC0's header, across which it will be hoisted, or FC1's header, across which it will be sunk. We reject cases where the dependency is a data hazard.


https://reviews.llvm.org/D131606

Files:
  llvm/lib/Transforms/Scalar/LoopFuse.cpp
  llvm/test/Transforms/LoopFusion/no_sink_hoist_load.ll
  llvm/test/Transforms/LoopFusion/no_sink_hoist_store.ll
  llvm/test/Transforms/LoopFusion/no_sink_hoist_unknown_function.ll
  llvm/test/Transforms/LoopFusion/simple.ll
  llvm/test/Transforms/LoopFusion/sink_load.ll
  llvm/test/Transforms/LoopFusion/sink_store.ll

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