[PATCH] D112696: CycleInfo: Introduce cycles as a generalization of loops

[Sameer Sahasrabuddhe via Phabricator via llvm-commits]

sameerds created this revision.
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LLVM loops cannot represent irreducible structures in the CFG. This
change introduce the concept of cycles as a generalization loops,
along with a CycleInfo analysis that discover a nested
hierarchy of such cycles. This is based on Havlak (1997), Nesting of
Reducible and Irreducible Loops.

The cycle analysis is implemented as a generic template and then
instatiated for LLVM IR and Machine IR. The template relies on a new
GenericSsaContext template which must be specialized when used for
each IR.

This review is a restart of an older review request:
https://reviews.llvm.org/D83094

Original implementation by Nicolai Hähnle <nicolai.haehnle at amd.com>,
with recent refactoring by Sameer Sahasrabuddhe <sameer.sahasrabuddhe at amd.com>


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D112696

Files:
  llvm/docs/CycleTerminology.rst
  llvm/docs/UserGuides.rst
  llvm/include/llvm/ADT/GenericCycleImpl.h
  llvm/include/llvm/ADT/GenericCycleInfo.h
  llvm/include/llvm/ADT/GenericSsaContext.h
  llvm/include/llvm/Analysis/CycleAnalysis.h
  llvm/include/llvm/CodeGen/MachineCycleAnalysis.h
  llvm/include/llvm/CodeGen/MachinePassRegistry.def
  llvm/include/llvm/CodeGen/MachineSsaContext.h
  llvm/include/llvm/IR/SsaContext.h
  llvm/include/llvm/InitializePasses.h
  llvm/lib/Analysis/Analysis.cpp
  llvm/lib/Analysis/CMakeLists.txt
  llvm/lib/Analysis/CycleAnalysis.cpp
  llvm/lib/CodeGen/CMakeLists.txt
  llvm/lib/CodeGen/CodeGen.cpp
  llvm/lib/CodeGen/MachineCycleAnalysis.cpp
  llvm/lib/CodeGen/MachineSsaContext.cpp
  llvm/lib/IR/CMakeLists.txt
  llvm/lib/IR/SsaContext.cpp
  llvm/lib/Passes/PassBuilder.cpp
  llvm/lib/Passes/PassRegistry.def
  llvm/test/Analysis/CycleInfo/basic.ll
  llvm/test/CodeGen/X86/cycle-info.mir

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