From e725c11b63a32c8a40136f627117d9339d97312b Mon Sep 17 00:00:00 2001
From: David Carlier <devnexen@gmail.com>
Date: Tue, 18 Sep 2018 10:31:10 +0000
Subject: [PATCH] [Xray] llvm-xray fix possible segfault

top argument when superior to the instrumentated code list capacity can lead to a segfault.

Reviewers: dberris

Reviewed By: dberris

Differential Revision: https://reviews.llvm.org/D52224


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@342461 91177308-0d34-0410-b5e6-96231b3b80d8
---
 tools/llvm-xray/xray-account.cpp | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/llvm-xray/xray-account.cpp b/tools/llvm-xray/xray-account.cpp
index 2776a888848..77de1de496f 100644
--- a/tools/llvm-xray/xray-account.cpp
+++ b/tools/llvm-xray/xray-account.cpp
@@ -358,8 +358,11 @@ void LatencyAccountant::exportStats(const XRayFileHeader &Header, F Fn) const {
     break;
   }
 
-  if (AccountTop > 0)
-    Results.erase(Results.begin() + AccountTop.getValue(), Results.end());
+  if (AccountTop > 0) {
+    auto MaxTop =
+        std::min(AccountTop.getValue(), static_cast<int>(Results.size()));
+    Results.erase(Results.begin() + MaxTop, Results.end());
+  }
 
   for (const auto &R : Results)
     Fn(std::get<0>(R), std::get<1>(R), std::get<2>(R));
-- 
2.11.0