fix crash in my previous patch

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86987 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/ConstantRange.cpp b/lib/Support/ConstantRange.cpp
index 4593eb9..e427f82 100644
--- a/lib/Support/ConstantRange.cpp
+++ b/lib/Support/ConstantRange.cpp
@@ -618,7 +618,7 @@
   APInt max = getUnsignedMax() << Amount.getUnsignedMax();
 
   // there's no overflow!
-  APInt Zeros(sizeof(unsigned)*8, getUnsignedMax().countLeadingZeros());
+  APInt Zeros(getBitWidth(), getUnsignedMax().countLeadingZeros());
   if (Zeros.uge(Amount.getUnsignedMax()))
     return ConstantRange(min, max);