From: Nick Kledzik <kledzik@apple.com>
Date: Tue, 2 Oct 2012 20:01:48 +0000 (+0000)
Subject: Improve overflow detection in StringRef::getAsUnsignedInteger().
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=6e033d6dcd374634a64825692342c555d2eff38f;p=oota-llvm.git

Improve overflow detection in StringRef::getAsUnsignedInteger().

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165038 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Support/StringRef.cpp b/lib/Support/StringRef.cpp
index 8aab4b2760e..f8e92084625 100644
--- a/lib/Support/StringRef.cpp
+++ b/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);