[PATCH] D152335: [Clang] Add check to Sema::AddAlignedAttr to verify active bits is not out of range

[Erich Keane via Phabricator via cfe-commits]

erichkeane added inline comments.


================
Comment at: clang/lib/Sema/SemaDeclAttr.cpp:4480
     MaximumAlignment = std::min(MaximumAlignment, uint64_t(8192));
-  if (AlignVal > MaximumAlignment) {
+  bool TooManyActiveBits = Alignment.getActiveBits() > llvm::APInt(64, MaximumAlignment).getActiveBits();
+
----------------
What is the purpose of using 'ActiveBits' here?  Why is this not a sub-set of the operator `>` from below?  That is, 'ActiveBits' allows for 0xFF when the 'MaxValue' is 0x80 (top bit set), but the operator > would have caught that anyway, right?  

Also, how does 'ActiveBits' work with negative numbers? 


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D152335/new/

https://reviews.llvm.org/D152335