[PATCH] D30416: [InstCombine] Redo reduceLoadOpStoreWidth in instcombine for bitfield store optimization.

[Wei Mi via Phabricator via llvm-commits]

wmi updated this revision to Diff 93018.
wmi added a reviewer: chandlerc.
wmi added a comment.
Herald added a subscriber: mgorny.

Revamp the patch.

- Extend bitfield store shrinking to handle and(or(and( ... or(load, C_1), MaskedVal_1), ..., C_N), MaskedVal_N))) pattern.
- Add bitfield load shrinking.
- Use memorySSA to do the safety check and maintain it on the fly.

With all these changes, llvm now can catch most of the shrinking opportunities for testcase http://lists.llvm.org/pipermail/llvm-commits/attachments/20170307/23ad5702/attachment-0001.cc, but still keep its bitfield coalescing ablity by putting the shrinking pass in the late pipeline.

I need to add testcases for bitfield load shrinking. Will send out patch update soon.


Repository:
  rL LLVM

https://reviews.llvm.org/D30416

Files:
  include/llvm/CodeGen/Passes.h
  include/llvm/IR/PatternMatch.h
  include/llvm/InitializePasses.h
  include/llvm/LinkAllPasses.h
  lib/CodeGen/CodeGen.cpp
  lib/CodeGen/TargetPassConfig.cpp
  lib/Transforms/Scalar/BitfieldShrinking.cpp
  lib/Transforms/Scalar/CMakeLists.txt
  test/CodeGen/ARM/bitfield-store.ll
  test/CodeGen/ARM/illegal-bitfield-loadstore.ll
  test/CodeGen/X86/bitfield-store.ll
  test/CodeGen/X86/illegal-bitfield-loadstore.ll
  tools/opt/opt.cpp

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