From 1b45675424ee28a72775b2b6928f3bb615b91f02 Mon Sep 17 00:00:00 2001
From: Aditya Nandakumar <aditya_nandakumar@apple.com>
Date: Wed, 17 May 2017 17:41:55 +0000
Subject: [PATCH] [GISel]: Fix undefined behavior in IRTranslator

Make sure IRTranslator->MachineIRBuilder->DebugLoc doesn't
outlive the DILocation. Clear it at the end of
IRTranslator::runOnMachineFunction

llvm-svn: 303277
---
 lib/CodeGen/GlobalISel/IRTranslator.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/CodeGen/GlobalISel/IRTranslator.cpp b/lib/CodeGen/GlobalISel/IRTranslator.cpp
index 811858f136e..77dfb13ac1f 100644
--- a/lib/CodeGen/GlobalISel/IRTranslator.cpp
+++ b/lib/CodeGen/GlobalISel/IRTranslator.cpp
@@ -1129,6 +1129,11 @@ void IRTranslator::finalizeFunction() {
   ValToVReg.clear();
   FrameIndices.clear();
   MachinePreds.clear();
+  // MachineIRBuilder::DebugLoc can outlive the DILocation it holds. Clear it
+  // to avoid accessing free’d memory (in runOnMachineFunction) and to avoid
+  // destroying it twice (in ~IRTranslator() and ~LLVMContext())
+  EntryBuilder = MachineIRBuilder();
+  CurBuilder = MachineIRBuilder();
 }
 
 bool IRTranslator::runOnMachineFunction(MachineFunction &CurMF) {