[PATCH] D30525: [APInt] Add setLowBits/setHighBits methods to APInt.

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.

There are quite a few places in the code base that do something like the following to set the high or low bits in an APInt.

KnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - 1);

For BitWidths larger than 64 this creates a short lived APInt with malloced storage. I think it might even call malloc twice. Its better to just provide methods that can set the necessary bits without the temporary APInt.

I'll update usages that benefit in a separate patch.


https://reviews.llvm.org/D30525

Files:
  include/llvm/ADT/APInt.h
  lib/Support/APInt.cpp
  unittests/ADT/APIntTest.cpp

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