From 35c79da3f890c28dabedbe1be3880972f706e105 Mon Sep 17 00:00:00 2001
From: Nick Kledzik <kledzik@apple.com>
Date: Tue, 2 Oct 2012 20:01:48 +0000
Subject: [PATCH] Improve overflow detection in
 StringRef::getAsUnsignedInteger().

llvm-svn: 165038
---
 llvm/lib/Support/StringRef.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/llvm/lib/Support/StringRef.cpp b/llvm/lib/Support/StringRef.cpp
index 8aab4b2..f8e9208 100644
--- a/llvm/lib/Support/StringRef.cpp
+++ b/llvm/lib/Support/StringRef.cpp
@@ -350,8 +350,8 @@ bool llvm::getAsUnsignedInteger(StringRef Str, unsigned Radix,
     unsigned long long PrevResult = Result;
     Result = Result*Radix+CharVal;
 
-    // Check for overflow.
-    if (Result < PrevResult)
+    // Check for overflow by shifting back and seeing if bits were lost.
+    if (Result/Radix < PrevResult)
       return true;
 
     Str = Str.substr(1);
-- 
2.7.4