[llvm] r303277 - [GISel]: Fix undefined behavior in IRTranslator

[Aditya Nandakumar via llvm-commits]

Author: aditya_nandakumar
Date: Wed May 17 12:41:55 2017
New Revision: 303277

URL: http://llvm.org/viewvc/llvm-project?rev=303277&view=rev
Log:
[GISel]: Fix undefined behavior in IRTranslator

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

Modified:
    llvm/trunk/lib/CodeGen/GlobalISel/IRTranslator.cpp

Modified: llvm/trunk/lib/CodeGen/GlobalISel/IRTranslator.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/GlobalISel/IRTranslator.cpp?rev=303277&r1=303276&r2=303277&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/GlobalISel/IRTranslator.cpp (original)
+++ llvm/trunk/lib/CodeGen/GlobalISel/IRTranslator.cpp Wed May 17 12:41:55 2017
@@ -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) {