2 files changed, 50 insertions, 6 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index a3e583588f0..b3d6ab81ed1 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1811,9 +1811,19 @@ void SelectionDAGBuilder::visitSPDescriptorParent(StackProtectorDescriptor &SPD,
 
   unsigned Align =
     TLI->getDataLayout()->getPrefTypeAlignment(IRGuard->getType());
-  SDValue Guard = DAG.getLoad(PtrTy, getCurSDLoc(), DAG.getEntryNode(),
-                              GuardPtr, MachinePointerInfo(IRGuard, 0),
-                              true, false, false, Align);
+
+  SDValue Guard;
+
+  // If useLoadStackGuardNode returns true, retrieve the guard value from
+  // the virtual register holding the value. Otherwise, emit a volatile load
+  // to retrieve the stack guard value.
+  if (TLI->useLoadStackGuardNode())
+    Guard = DAG.getCopyFromReg(DAG.getEntryNode(), getCurSDLoc(),
+                               SPD.getGuardReg(), PtrTy);
+  else
+    Guard = DAG.getLoad(PtrTy, getCurSDLoc(), DAG.getEntryNode(),
+                        GuardPtr, MachinePointerInfo(IRGuard, 0),
+                        true, false, false, Align);
 
   SDValue StackSlot = DAG.getLoad(PtrTy, getCurSDLoc(), DAG.getEntryNode(),
                                   StackSlotPtr,
@@ -5228,8 +5238,35 @@ SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I, unsigned Intrinsic) {
     MachineFunction &MF = DAG.getMachineFunction();
     MachineFrameInfo *MFI = MF.getFrameInfo();
     EVT PtrTy = TLI->getPointerTy();
+    SDValue Src, Chain = getRoot();
+
+    if (TLI->useLoadStackGuardNode()) {
+      // Emit a LOAD_STACK_GUARD node.
+      MachineSDNode *Node = DAG.getMachineNode(TargetOpcode::LOAD_STACK_GUARD,
+                                               sdl, PtrTy, Chain);
+      LoadInst *LI = cast<LoadInst>(I.getArgOperand(0));
+      MachinePointerInfo MPInfo(LI->getPointerOperand());
+      MachineInstr::mmo_iterator MemRefs = MF.allocateMemRefsArray(1);
+      unsigned Flags = MachineMemOperand::MOLoad |
+                       MachineMemOperand::MOInvariant;
+      *MemRefs = MF.getMachineMemOperand(MPInfo, Flags,
+                                         PtrTy.getSizeInBits() / 8,
+                                         DAG.getEVTAlignment(PtrTy));
+      Node->setMemRefs(MemRefs, MemRefs + 1);
+
+      // Copy the guard value to a virtual register so that it can be
+      // retrieved in the epilogue.
+      Src = SDValue(Node, 0);
+      const TargetRegisterClass *RC =
+          TLI->getRegClassFor(Src.getSimpleValueType());
+      unsigned Reg = MF.getRegInfo().createVirtualRegister(RC);
+
+      SPDescriptor.setGuardReg(Reg);
+      Chain = DAG.getCopyToReg(Chain, sdl, Reg, Src);
+    } else {
+      Src = getValue(I.getArgOperand(0));   // The guard's value.
+    }
 
-    SDValue Src = getValue(I.getArgOperand(0));   // The guard's value.
     AllocaInst *Slot = cast<AllocaInst>(I.getArgOperand(1));
 
     int FI = FuncInfo.StaticAllocaMap[Slot];
@@ -5238,7 +5275,7 @@ SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I, unsigned Intrinsic) {
     SDValue FIN = DAG.getFrameIndex(FI, PtrTy);
 
     // Store the stack protector onto the stack.
-    Res = DAG.getStore(getRoot(), sdl, Src, FIN,
+    Res = DAG.getStore(Chain, sdl, Src, FIN,
                        MachinePointerInfo::getFixedStack(FI),
                        true, false, 0);
     setValue(&I, Res);
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index 84679f98d84..cf0846f3430 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -397,7 +397,8 @@ private:
   class StackProtectorDescriptor {
   public:
     StackProtectorDescriptor() : ParentMBB(nullptr), SuccessMBB(nullptr),
-                                 FailureMBB(nullptr), Guard(nullptr) { }
+                                 FailureMBB(nullptr), Guard(nullptr),
+                                 GuardReg(0) { }
     ~StackProtectorDescriptor() { }
 
     /// Returns true if all fields of the stack protector descriptor are
@@ -455,6 +456,9 @@ private:
     MachineBasicBlock *getFailureMBB() { return FailureMBB; }
     const Value *getGuard() { return Guard; }
 
+    unsigned getGuardReg() const { return GuardReg; }
+    void setGuardReg(unsigned R) { GuardReg = R; }
+
   private:
     /// The basic block for which we are generating the stack protector.
     ///
@@ -477,6 +481,9 @@ private:
     /// stack protector stack slot.
     const Value *Guard;
 
+    /// The virtual register holding the stack guard value.
+    unsigned GuardReg;
+
     /// Add a successor machine basic block to ParentMBB. If the successor mbb
     /// has not been created yet (i.e. if SuccMBB = 0), then the machine basic
     /// block will be created.