[llvm] r307430 - [APInt] Add a fastpath for the single word case of isOneValue to match isNullValue, isAllOnesValue, etc. NFCI

[Craig Topper via llvm-commits]

Author: ctopper
Date: Fri Jul  7 12:56:18 2017
New Revision: 307430

URL: http://llvm.org/viewvc/llvm-project?rev=307430&view=rev
Log:
[APInt] Add a fastpath for the single word case of isOneValue to match isNullValue, isAllOnesValue, etc. NFCI

Modified:
    llvm/trunk/include/llvm/ADT/APInt.h

Modified: llvm/trunk/include/llvm/ADT/APInt.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/APInt.h?rev=307430&r1=307429&r2=307430&view=diff
==============================================================================
--- llvm/trunk/include/llvm/ADT/APInt.h (original)
+++ llvm/trunk/include/llvm/ADT/APInt.h Fri Jul  7 12:56:18 2017
@@ -401,7 +401,11 @@ public:
   /// \brief Determine if this is a value of 1.
   ///
   /// This checks to see if the value of this APInt is one.
-  bool isOneValue() const { return getActiveBits() == 1; }
+  bool isOneValue() const {
+    if (isSingleWord())
+      return U.VAL == 1;
+    return countLeadingZerosSlowCase() == BitWidth - 1;
+  }
 
   /// \brief Determine if this is the largest unsigned value.
   ///