From e229ec5bfcc937d629d7706416108d02cc103bb4 Mon Sep 17 00:00:00 2001
From: Alexey Samsonov <vonosmas@gmail.com>
Date: Wed, 20 Aug 2014 21:40:15 +0000
Subject: [PATCH] Fix null reference creation in SelectionDAG constructor.

Store TargetSelectionDAGInfo as a pointer instead of a reference:
getSelectionDAGInfo() may not be implemented for certain backends
(e.g. it's not currently implemented for R600).

This bug is reported by UBSan.

llvm-svn: 216129
---
 llvm/include/llvm/CodeGen/SelectionDAG.h       |  4 ++--
 llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp | 17 +++++++----------
 2 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/llvm/include/llvm/CodeGen/SelectionDAG.h b/llvm/include/llvm/CodeGen/SelectionDAG.h
index 48bffe672f8e..f7d21f9c53d2 100644
--- a/llvm/include/llvm/CodeGen/SelectionDAG.h
+++ b/llvm/include/llvm/CodeGen/SelectionDAG.h
@@ -168,7 +168,7 @@ void checkForCycles(const SelectionDAG *DAG, bool force = false);
 ///
 class SelectionDAG {
   const TargetMachine &TM;
-  const TargetSelectionDAGInfo &TSI;
+  const TargetSelectionDAGInfo *TSI;
   const TargetLowering *TLI;
   MachineFunction *MF;
   LLVMContext *Context;
@@ -279,7 +279,7 @@ public:
   const TargetMachine &getTarget() const { return TM; }
   const TargetSubtargetInfo &getSubtarget() const { return MF->getSubtarget(); }
   const TargetLowering &getTargetLoweringInfo() const { return *TLI; }
-  const TargetSelectionDAGInfo &getSelectionDAGInfo() const { return TSI; }
+  const TargetSelectionDAGInfo &getSelectionDAGInfo() const { return *TSI; }
   LLVMContext *getContext() const {return Context; }
 
   /// viewGraph - Pop up a GraphViz/gv window with the DAG rendered using 'dot'.
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index c15426771aff..4d8d43570d9f 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -907,7 +907,7 @@ unsigned SelectionDAG::getEVTAlignment(EVT VT) const {
 
 // EntryNode could meaningfully have debug info if we can find it...
 SelectionDAG::SelectionDAG(const TargetMachine &tm, CodeGenOpt::Level OL)
-    : TM(tm), TSI(*tm.getSubtargetImpl()->getSelectionDAGInfo()), TLI(nullptr),
+    : TM(tm), TSI(tm.getSubtargetImpl()->getSelectionDAGInfo()), TLI(nullptr),
       OptLevel(OL),
       EntryNode(ISD::EntryToken, 0, DebugLoc(), getVTList(MVT::Other)),
       Root(getEntryNode()), NewNodesMustHaveLegalTypes(false),
@@ -4228,9 +4228,8 @@ SDValue SelectionDAG::getMemcpy(SDValue Chain, SDLoc dl, SDValue Dst,
   // Then check to see if we should lower the memcpy with target-specific
   // code. If the target chooses to do this, this is the next best.
   SDValue Result =
-    TSI.EmitTargetCodeForMemcpy(*this, dl, Chain, Dst, Src, Size, Align,
-                                isVol, AlwaysInline,
-                                DstPtrInfo, SrcPtrInfo);
+      TSI->EmitTargetCodeForMemcpy(*this, dl, Chain, Dst, Src, Size, Align,
+                                   isVol, AlwaysInline, DstPtrInfo, SrcPtrInfo);
   if (Result.getNode())
     return Result;
 
@@ -4296,9 +4295,8 @@ SDValue SelectionDAG::getMemmove(SDValue Chain, SDLoc dl, SDValue Dst,
 
   // Then check to see if we should lower the memmove with target-specific
   // code. If the target chooses to do this, this is the next best.
-  SDValue Result =
-    TSI.EmitTargetCodeForMemmove(*this, dl, Chain, Dst, Src, Size, Align, isVol,
-                                 DstPtrInfo, SrcPtrInfo);
+  SDValue Result = TSI->EmitTargetCodeForMemmove(
+      *this, dl, Chain, Dst, Src, Size, Align, isVol, DstPtrInfo, SrcPtrInfo);
   if (Result.getNode())
     return Result;
 
@@ -4351,9 +4349,8 @@ SDValue SelectionDAG::getMemset(SDValue Chain, SDLoc dl, SDValue Dst,
 
   // Then check to see if we should lower the memset with target-specific
   // code. If the target chooses to do this, this is the next best.
-  SDValue Result =
-    TSI.EmitTargetCodeForMemset(*this, dl, Chain, Dst, Src, Size, Align, isVol,
-                                DstPtrInfo);
+  SDValue Result = TSI->EmitTargetCodeForMemset(*this, dl, Chain, Dst, Src,
+                                                Size, Align, isVol, DstPtrInfo);
   if (Result.getNode())
     return Result;