From 1531f30ccc28b21915902a00be8792c39d35410a Mon Sep 17 00:00:00 2001
From: Sebastian Pop <sebpop@gmail.com>
Date: Thu, 22 Sep 2016 17:22:58 +0000
Subject: GVN-hoist: do not dereference null pointers

there may be basic blocks without memory accesses, in which case the
list of accesses is a null pointer.

llvm-svn: 282175
---
 llvm/lib/Transforms/Scalar/GVNHoist.cpp | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'llvm/lib/Transforms')

diff --git a/llvm/lib/Transforms/Scalar/GVNHoist.cpp b/llvm/lib/Transforms/Scalar/GVNHoist.cpp
index 3c2ac6fcd5f..03fd4872a0a 100644
--- a/llvm/lib/Transforms/Scalar/GVNHoist.cpp
+++ b/llvm/lib/Transforms/Scalar/GVNHoist.cpp
@@ -338,6 +338,9 @@ private:
     bool ReachedNewPt = false;
     MemoryLocation DefLoc = MemoryLocation::get(OldPt);
     const MemorySSA::AccessList *Acc = MSSA->getBlockAccesses(BB);
+    if (!Acc)
+      return false;
+
     for (const MemoryAccess &MA : *Acc) {
       auto *MU = dyn_cast<MemoryUse>(&MA);
       if (!MU)
-- 
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