[PATCH] SimplifyCFG: recognise and simplify more no-op resumes.

[Duncan Sands]

  Hi Peter,

  > This is specifically targeted to identify the BB structure used
  > by DragonEgg but it also resulted in a small (~4KB) decrease in
  > binary size for a Clang-built Clang compiled with exceptions.
  >
  > http://llvm-reviews.chandlerc.com/D563
  >
  > Files:
  >    lib/Transforms/Utils/SimplifyCFG.cpp
  >    test/Transforms/SimplifyCFG/TrivialLPads.ll

  it looks like it would be helpful if dragonegg didn't decompose the
  exception pointer/filter pair and recompose them at the end; instead
  it could pass them around as a pair and extract an element only when
  it needs to be used individually.  For example, the pair would be passed
  to the resume as a pair, rather than first reconstructing the pair from
  its elements.  What do you think?

  Ciao, Duncan.

http://llvm-reviews.chandlerc.com/D563