From 846909e2ab0bd279ae2a8ec86074521f59c49eb3 Mon Sep 17 00:00:00 2001
From: Jan Kratochvil <jan.kratochvil@redhat.com>
Date: Fri, 5 Jun 2020 11:59:26 +0200
Subject: [PATCH] [lldb] Fix UBSan regression in GetSLEB128

It regressed recently by my: https://reviews.llvm.org/D81119
---
 lldb/source/Utility/DataExtractor.cpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lldb/source/Utility/DataExtractor.cpp b/lldb/source/Utility/DataExtractor.cpp
index 5f4abb8..023190b 100644
--- a/lldb/source/Utility/DataExtractor.cpp
+++ b/lldb/source/Utility/DataExtractor.cpp
@@ -930,8 +930,10 @@ int64_t DataExtractor::GetSLEB128(offset_t *offset_ptr) const {
     }
 
     // Sign bit of byte is 2nd high order bit (0x40)
-    if (shift < size && (byte & 0x40))
-      result |= -(static_cast<int64_t>(1) << shift);
+    if (shift < size && (byte & 0x40)) {
+      // -(static_cast<int64_t>(1) << 63) errors on the negation with UBSan.
+      result |= -(static_cast<uint64_t>(1) << shift);
+    }
 
     *offset_ptr += bytecount;
     return result;
-- 
2.7.4