From 9f2d83ffdb574e2bccee264ca9de7c95fe32efbc Mon Sep 17 00:00:00 2001
From: Andrew Kaylor <andrew.kaylor@intel.com>
Date: Wed, 14 Dec 2016 19:30:18 +0000
Subject: [PATCH] [WinEH] Avoid holding references to BlockColor (DenseMap)
 entries while inserting new elements

Differential Revision: https://reviews.llvm.org/D27693

llvm-svn: 289694
---
 lib/CodeGen/WinEHPrepare.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/CodeGen/WinEHPrepare.cpp b/lib/CodeGen/WinEHPrepare.cpp
index 8b81a48a7b1..568720c66e5 100644
--- a/lib/CodeGen/WinEHPrepare.cpp
+++ b/lib/CodeGen/WinEHPrepare.cpp
@@ -1202,8 +1202,12 @@ void WinEHPrepare::replaceUseWithLoad(Value *V, Use &U, AllocaInst *&SpillSlot,
       Goto->setSuccessor(0, PHIBlock);
       CatchRet->setSuccessor(NewBlock);
       // Update the color mapping for the newly split edge.
+      // Grab a reference to the ColorVector to be inserted before getting the
+      // reference to the vector we are copying because inserting the new
+      // element in BlockColors might cause the map to be reallocated.
+      ColorVector &ColorsForNewBlock = BlockColors[NewBlock];
       ColorVector &ColorsForPHIBlock = BlockColors[PHIBlock];
-      BlockColors[NewBlock] = ColorsForPHIBlock;
+      ColorsForNewBlock = ColorsForPHIBlock;
       for (BasicBlock *FuncletPad : ColorsForPHIBlock)
         FuncletBlocks[FuncletPad].push_back(NewBlock);
       // Treat the new block as incoming for load insertion.