[PATCH] [LCSSA] Handle PHI insertion in disjoint loops

[Bruno Cardoso Lopes]

Hi chandlerc, hfinkel,

Take two disjoint Loops L1 and L2.

LoopSimplify skips to simplify some loops (e.g. when indirect branches are involved). In such situations, it can happen that an exit for L1 is the header of L2. Thus, when we create PHIs in one of such exits we are also inserting PHIs in L2 header.

This could break LCSSA form for L2 because these inserted PHIs can also have uses in L2 exits, which are never handled in the current implementation. Provide a fix for this corner case and test that we don't assert/crash on that.

REPOSITORY
  rL LLVM

http://reviews.llvm.org/D6624

Files:
  include/llvm/Transforms/Utils/LoopUtils.h
  lib/Transforms/Scalar/LICM.cpp
  lib/Transforms/Utils/LCSSA.cpp
  lib/Transforms/Utils/LoopUnroll.cpp
  test/Transforms/LCSSA/indirectbr.ll

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