Teach selectiondag how to handle the stackprotectorcheck intrinsic.

[oota-llvm.git] / lib / CodeGen / SelectionDAG / SelectionDAGISel.cpp

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 17ccdb2bd5cc4339a4c206df21be577e9781b7dc..597a72b6638961bd243512a7b1bdbf9935194b14 100644 (file)
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -1144,6 +1144,42 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
 
   delete FastIS;
   SDB->clearDanglingDebugInfo();
+  SDB->SPDescriptor.resetPerFunctionState();
+}
+
+/// Find the split point at which to splice the end of BB into its success stack
+/// protector check machine basic block.
+static MachineBasicBlock::iterator
+FindSplitPointForStackProtector(MachineBasicBlock *BB, DebugLoc DL) {
+  MachineFunction *MF = BB->getParent();
+  MachineRegisterInfo &MRI = MF->getRegInfo();
+  const TargetMachine &TM = MF->getTarget();
+  const TargetInstrInfo *TII = TM.getInstrInfo();
+  const TargetRegisterInfo *TRI = TM.getRegisterInfo();
+
+  MachineBasicBlock::iterator SplitPoint = BB->getFirstTerminator();
+  if (SplitPoint == BB->begin())
+    return SplitPoint;
+
+  MachineBasicBlock::iterator Start = BB->begin();
+  MachineBasicBlock::iterator Previous = SplitPoint;
+  --Previous;
+
+  while (Previous->isCopy() || Previous->isImplicitDef()) {
+    MachineInstr::mop_iterator OPI = Previous->operands_begin();
+
+    if (!OPI->isReg() || !OPI->isDef() ||
+        (!TargetRegisterInfo::isPhysicalRegister(OPI->getReg()) &&
+         !Previous->isImplicitDef()))
+      break;
+
+    SplitPoint = Previous;
+    if (Previous == Start)
+      break;
+    --Previous;
+  }
+
+  return SplitPoint;
 }
 
 void
@@ -1156,11 +1192,13 @@ SelectionDAGISel::FinishBasicBlock() {
                  << FuncInfo->PHINodesToUpdate[i].first
                  << ", " << FuncInfo->PHINodesToUpdate[i].second << ")\n");
 
+  const bool MustUpdatePHINodes = SDB->SwitchCases.empty() &&
+                                  SDB->JTCases.empty() &&
+                                  SDB->BitTestCases.empty();
+
   // Next, now that we know what the last MBB the LLVM BB expanded is, update
   // PHI nodes in successors.
-  if (SDB->SwitchCases.empty() &&
-      SDB->JTCases.empty() &&
-      SDB->BitTestCases.empty()) {
+  if (MustUpdatePHINodes) {
     for (unsigned i = 0, e = FuncInfo->PHINodesToUpdate.size(); i != e; ++i) {
       MachineInstrBuilder PHI(*MF, FuncInfo->PHINodesToUpdate[i].first);
       assert(PHI->isPHI() &&
@@ -1169,9 +1207,54 @@ SelectionDAGISel::FinishBasicBlock() {
         continue;
       PHI.addReg(FuncInfo->PHINodesToUpdate[i].second).addMBB(FuncInfo->MBB);
     }
-    return;
   }
 
+  // Handle stack protector.
+  if (SDB->SPDescriptor.shouldEmitStackProtector()) {
+    MachineBasicBlock *ParentMBB = SDB->SPDescriptor.getParentMBB();
+    MachineBasicBlock *SuccessMBB = SDB->SPDescriptor.getSuccessMBB();
+
+    // Find the split point to split the parent mbb. At the same time copy all
+    // physical registers used in the tail of parent mbb into virtual registers
+    // before the split point and back into physical registers after the split
+    // point. This prevents us needing to deal with Live-ins and many other
+    // register allocation issues caused by us splitting the parent mbb. The
+    // register allocator will clean up said virtual copies later on.
+    MachineBasicBlock::iterator SplitPoint =
+      FindSplitPointForStackProtector(ParentMBB, SDB->getCurDebugLoc());
+
+    // Splice the terminator of ParentMBB into SuccessMBB.
+    SuccessMBB->splice(SuccessMBB->end(), ParentMBB,
+                       SplitPoint,
+                       ParentMBB->end());
+
+    // Add compare/jump on neq/jump to the parent BB.
+    FuncInfo->MBB = ParentMBB;
+    FuncInfo->InsertPt = ParentMBB->end();
+    SDB->visitSPDescriptorParent(SDB->SPDescriptor, ParentMBB);
+    CurDAG->setRoot(SDB->getRoot());
+    SDB->clear();
+    CodeGenAndEmitDAG();
+
+    // CodeGen Failure MBB if we have not codegened it yet.
+    MachineBasicBlock *FailureMBB = SDB->SPDescriptor.getFailureMBB();
+    if (!FailureMBB->size()) {
+      FuncInfo->MBB = FailureMBB;
+      FuncInfo->InsertPt = FailureMBB->end();
+      SDB->visitSPDescriptorFailure(SDB->SPDescriptor);
+      CurDAG->setRoot(SDB->getRoot());
+      SDB->clear();
+      CodeGenAndEmitDAG();
+    }
+
+    // Clear the Per-BB State.
+    SDB->SPDescriptor.resetPerBBState();
+  }
+
+  // If we updated PHI Nodes, return early.
+  if (MustUpdatePHINodes)
+    return;
+
   for (unsigned i = 0, e = SDB->BitTestCases.size(); i != e; ++i) {
     // Lower header first, if it wasn't already lowered
     if (!SDB->BitTestCases[i].Emitted) {