From 242320399f791e62e06cd9fdd1154c0732bf1ee2 Mon Sep 17 00:00:00 2001
From: Alexey Samsonov <vonosmas@gmail.com>
Date: Wed, 20 Aug 2014 18:30:07 +0000
Subject: [PATCH] Fix undefined behavior (left shift by 64 bits) in
 ScaledNumber::toString().

This bug is reported by UBSan.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216116 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Support/ScaledNumber.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/Support/ScaledNumber.cpp b/lib/Support/ScaledNumber.cpp
index 3fe027ba331..fc6d4e7be43 100644
--- a/lib/Support/ScaledNumber.cpp
+++ b/lib/Support/ScaledNumber.cpp
@@ -220,6 +220,9 @@ std::string ScaledNumberBase::toString(uint64_t D, int16_t E, int Width,
   } else if (E > -64) {
     Above0 = D >> -E;
     Below0 = D << (64 + E);
+  } else if (E == -64) {
+    // Special case: shift by 64 bits is undefined behavior.
+    Below0 = D;
   } else if (E > -120) {
     Below0 = D >> (-E - 64);
     Extra = D << (128 + E);