[PATCH] D32212: Create some helpers for generating bit masks

[Adrian McCarthy via Phabricator via llvm-commits]

amccarth added inline comments.


================
Comment at: llvm/trunk/include/llvm/Support/MathExtras.h:207
+  assert(N <= Bits && "Invalid bit index");
+  return -T(N != 0) & (T(-1) >> (Bits - N));
+}
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Be aware that this can lead to compiler warnings, at least in MSVC, if T is an unsigned type:

 [[ https://msdn.microsoft.com/en-us/library/4kh09110.aspx |  C4146: unary minus operator applied to unsigned type, result still unsigned ]]

Depending on the specific details, this can be a level 2 or level 3 warning.  I'm surprised the tests aren't triggering it.  We must disable this warning somewhere.




Repository:
  rL LLVM

https://reviews.llvm.org/D32212