APInt has a method for determining whether a number is a power of 2
which is more efficient than countPopulation - use it.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124283 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index 5320fa0..aa7769e 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -656,7 +656,7 @@
 /// types and vectors of integers.
 bool llvm::isPowerOfTwo(Value *V, const TargetData *TD, unsigned Depth) {
   if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
-    return CI->getValue().countPopulation() == 1;
+    return CI->getValue().isPowerOf2();
   // TODO: Handle vector constants.
 
   // 1 << X is clearly a power of two if the one is not shifted off the end.  If