[all-commits] [llvm/llvm-project] 9b8d7f: [Transforms] Refactor CreateControlFlowHub

[Sameer Sahasrabuddhe via All-commits]

  Branch: refs/heads/users/ssahasra/control-flow-hub
  Home:   https://github.com/llvm/llvm-project
  Commit: 9b8d7f65680155f04bc754aebd4d820bad743581
      https://github.com/llvm/llvm-project/commit/9b8d7f65680155f04bc754aebd4d820bad743581
  Author: Sameer Sahasrabuddhe <sameer.sahasrabuddhe at amd.com>
  Date:   2024-08-13 (Tue, 13 Aug 2024)

  Changed paths:
    M llvm/include/llvm/Transforms/Utils/BasicBlockUtils.h
    A llvm/include/llvm/Transforms/Utils/ControlFlowUtils.h
    M llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
    M llvm/lib/Transforms/Utils/CMakeLists.txt
    A llvm/lib/Transforms/Utils/ControlFlowUtils.cpp
    M llvm/lib/Transforms/Utils/FixIrreducible.cpp
    M llvm/lib/Transforms/Utils/UnifyLoopExits.cpp
    M llvm/test/CodeGen/AMDGPU/local-atomicrmw-fadd.ll
    M llvm/test/Transforms/FixIrreducible/basic.ll
    M llvm/test/Transforms/FixIrreducible/bug45623.ll
    M llvm/test/Transforms/FixIrreducible/nested.ll
    M llvm/test/Transforms/FixIrreducible/switch.ll
    M llvm/test/Transforms/FixIrreducible/unreachable.ll

  Log Message:
  -----------
  [Transforms] Refactor CreateControlFlowHub

CreateControlFlowHub is a method that redirects control flow edges from a set of
incoming blocks to a set of outgoing blocks through a new set of "guard" blocks.
This is now refactored into a separate file with one enhancement: The input to
the method is now a set of branches rather than two sets of blocks.

The original implementation reroutes every edge from incoming blocks to outgoing
blocks. But it is possible that for some incoming block InBB, some successor S
might be in the set of outgoing blocks, but that particular edge should not be
rerouted. The new implementation makes this possible by allowing the user to
specify the targets of each branch that need to be rerouted.

This is needed when improving the implementation of FixIrreducible #101386. Current
uses in FixIrreducible and UnifyLoopExits do not demonstrate this finer control
over the edges being rerouted.



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