Fix misleading comment for getOrEnforceKnownAlignment

It does not return 0 to indicate failure, and returns the known
alignment.

llvm-svn: 281350

llvm/lib/Transforms/Utils/Local.cpp

@@ -1001,10 +1001,6 @@ static unsigned enforceKnownAlignment(Value *V, unsigned Align,
   return Align;
 }
 
-/// getOrEnforceKnownAlignment - If the specified pointer has an alignment that
-/// we can determine, return it, otherwise return 0.  If PrefAlign is specified,
-/// and it is more than the alignment of the ultimate object, see if we can
-/// increase the alignment of the ultimate object, making this check succeed.
 unsigned llvm::getOrEnforceKnownAlignment(Value *V, unsigned PrefAlign,
                                           const DataLayout &DL,
                                           const Instruction *CxtI,