[PATCH] D21183: Better selection of common base address in constant hoisting

[Sjoerd Meijer via llvm-commits]

SjoerdMeijer created this revision.
SjoerdMeijer added reviewers: jmolloy, mcrosier, ributzka.
SjoerdMeijer added a subscriber: llvm-commits.
Herald added a subscriber: aemerson.

This implements a more optimal algorithm for selecting a base constant in constant hoisting. It not only takes into account the number of uses of constants, but now also the resulting integer range of the offsets. Thus, the algorithm maximizes the number of uses within an integer range that will enable more efficient code generation. On ARM, for example, this will enable code size optimisations because less negative offsets will be created. Negative offsets/immediates are not supported by Thumb1 thus preventing more compact instruction encoding.

http://reviews.llvm.org/D21183

Files:
  include/llvm/Analysis/TargetTransformInfo.h
  include/llvm/Analysis/TargetTransformInfoImpl.h
  lib/Analysis/TargetTransformInfo.cpp
  lib/Target/ARM/ARMTargetTransformInfo.cpp
  lib/Target/ARM/ARMTargetTransformInfo.h
  lib/Transforms/Scalar/ConstantHoisting.cpp
  test/Transforms/ConstantHoisting/ARM/const-addr-no-neg-offset.ll
  test/Transforms/ConstantHoisting/PowerPC/masks.ll
  test/Transforms/ConstantHoisting/X86/phi.ll

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