Add __builtin_setjmp/_longjmp supprt in X86 backend

- Besides used in SjLj exception handling, __builtin_setjmp/__longjmp is also
  used as a light-weight replacement of setjmp/longjmp which are used to
  implementation continuation, user-level threading, and etc. The support added
  in this patch ONLY addresses this usage and is NOT intended to support SjLj
  exception handling as zero-cost DWARF exception handling is used by default
  in X86.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165989 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 202 insertions, 0 deletions

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 7916ccdeb3..b2537c659d 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -457,6 +457,14 @@ X86TargetLowering::X86TargetLowering(X86TargetMachine &TM)
     setOperationAction(ISD::SETCC         , MVT::i64  , Custom);
   }
   setOperationAction(ISD::EH_RETURN       , MVT::Other, Custom);
+  // NOTE: EH_SJLJ_SETJMP/_LONGJMP supported here is NOT intened to support
+  // SjLj exception handling but a light-weight setjmp/longjmp replacement to
+  // support continuation, user-level threading, and etc.. As a result, not
+  // other SjLj exception interfaces are implemented and please don't build
+  // your own exception handling based on them.
+  // LLVM/Clang supports zero-cost DWARF exception handling.
+  setOperationAction(ISD::EH_SJLJ_SETJMP, MVT::i32, Custom);
+  setOperationAction(ISD::EH_SJLJ_LONGJMP, MVT::Other, Custom);
 
   // Darwin ABI issue.
   setOperationAction(ISD::ConstantPool    , MVT::i32  , Custom);
@@ -10351,6 +10359,21 @@ SDValue X86TargetLowering::LowerEH_RETURN(SDValue Op, SelectionDAG &DAG) const {
                      Chain, DAG.getRegister(StoreAddrReg, getPointerTy()));
 }
 
+SDValue X86TargetLowering::lowerEH_SJLJ_SETJMP(SDValue Op,
+                                               SelectionDAG &DAG) const {
+  DebugLoc DL = Op.getDebugLoc();
+  return DAG.getNode(X86ISD::EH_SJLJ_SETJMP, DL,
+                     DAG.getVTList(MVT::i32, MVT::Other),
+                     Op.getOperand(0), Op.getOperand(1));
+}
+
+SDValue X86TargetLowering::lowerEH_SJLJ_LONGJMP(SDValue Op,
+                                                SelectionDAG &DAG) const {
+  DebugLoc DL = Op.getDebugLoc();
+  return DAG.getNode(X86ISD::EH_SJLJ_LONGJMP, DL, MVT::Other,
+                     Op.getOperand(0), Op.getOperand(1));
+}
+
 static SDValue LowerADJUST_TRAMPOLINE(SDValue Op, SelectionDAG &DAG) {
   return Op.getOperand(0);
 }
@@ -11375,6 +11398,8 @@ SDValue X86TargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) const {
                                 return LowerFRAME_TO_ARGS_OFFSET(Op, DAG);
   case ISD::DYNAMIC_STACKALLOC: return LowerDYNAMIC_STACKALLOC(Op, DAG);
   case ISD::EH_RETURN:          return LowerEH_RETURN(Op, DAG);
+  case ISD::EH_SJLJ_SETJMP:     return lowerEH_SJLJ_SETJMP(Op, DAG);
+  case ISD::EH_SJLJ_LONGJMP:    return lowerEH_SJLJ_LONGJMP(Op, DAG);
   case ISD::INIT_TRAMPOLINE:    return LowerINIT_TRAMPOLINE(Op, DAG);
   case ISD::ADJUST_TRAMPOLINE:  return LowerADJUST_TRAMPOLINE(Op, DAG);
   case ISD::FLT_ROUNDS_:        return LowerFLT_ROUNDS_(Op, DAG);
@@ -11667,6 +11692,8 @@ const char *X86TargetLowering::getTargetNodeName(unsigned Opcode) const {
   case X86ISD::TLSADDR:            return "X86ISD::TLSADDR";
   case X86ISD::TLSBASEADDR:        return "X86ISD::TLSBASEADDR";
   case X86ISD::TLSCALL:            return "X86ISD::TLSCALL";
+  case X86ISD::EH_SJLJ_SETJMP:     return "X86ISD::EH_SJLJ_SETJMP";
+  case X86ISD::EH_SJLJ_LONGJMP:    return "X86ISD::EH_SJLJ_LONGJMP";
   case X86ISD::EH_RETURN:          return "X86ISD::EH_RETURN";
   case X86ISD::TC_RETURN:          return "X86ISD::TC_RETURN";
   case X86ISD::FNSTCW16m:          return "X86ISD::FNSTCW16m";
@@ -13213,6 +13240,173 @@ X86TargetLowering::EmitLoweredTLSCall(MachineInstr *MI,
 }
 
 MachineBasicBlock *
+X86TargetLowering::emitEHSjLjSetJmp(MachineInstr *MI,
+                                    MachineBasicBlock *MBB) const {
+  DebugLoc DL = MI->getDebugLoc();
+  const TargetInstrInfo *TII = getTargetMachine().getInstrInfo();
+
+  MachineFunction *MF = MBB->getParent();
+  MachineRegisterInfo &MRI = MF->getRegInfo();
+
+  const BasicBlock *BB = MBB->getBasicBlock();
+  MachineFunction::iterator I = MBB;
+  ++I;
+
+  // Memory Reference
+  MachineInstr::mmo_iterator MMOBegin = MI->memoperands_begin();
+  MachineInstr::mmo_iterator MMOEnd = MI->memoperands_end();
+
+  unsigned DstReg;
+  unsigned MemOpndSlot = 0;
+
+  unsigned CurOp = 0;
+
+  DstReg = MI->getOperand(CurOp++).getReg();
+  const TargetRegisterClass *RC = MRI.getRegClass(DstReg);
+  assert(RC->hasType(MVT::i32) && "Invalid destination!");
+  unsigned mainDstReg = MRI.createVirtualRegister(RC);
+  unsigned restoreDstReg = MRI.createVirtualRegister(RC);
+
+  MemOpndSlot = CurOp;
+
+  MVT PVT = getPointerTy();
+  assert((PVT == MVT::i64 || PVT == MVT::i32) &&
+         "Invalid Pointer Size!");
+
+  // For v = setjmp(buf), we generate
+  //
+  // thisMBB:
+  //  buf[Label_Offset] = ljMBB
+  //  SjLjSetup restoreMBB
+  //
+  // mainMBB:
+  //  v_main = 0
+  //
+  // sinkMBB:
+  //  v = phi(main, restore)
+  //
+  // restoreMBB:
+  //  v_restore = 1
+
+  MachineBasicBlock *thisMBB = MBB;
+  MachineBasicBlock *mainMBB = MF->CreateMachineBasicBlock(BB);
+  MachineBasicBlock *sinkMBB = MF->CreateMachineBasicBlock(BB);
+  MachineBasicBlock *restoreMBB = MF->CreateMachineBasicBlock(BB);
+  MF->insert(I, mainMBB);
+  MF->insert(I, sinkMBB);
+  MF->push_back(restoreMBB);
+
+  MachineInstrBuilder MIB;
+
+  // Transfer the remainder of BB and its successor edges to sinkMBB.
+  sinkMBB->splice(sinkMBB->begin(), MBB,
+                  llvm::next(MachineBasicBlock::iterator(MI)), MBB->end());
+  sinkMBB->transferSuccessorsAndUpdatePHIs(MBB);
+
+  // thisMBB:
+  unsigned PtrImmStoreOpc = (PVT == MVT::i64) ? X86::MOV64mi32 : X86::MOV32mi;
+  const int64_t Label_Offset = 1 * PVT.getStoreSize();
+
+  // Store IP
+  MIB = BuildMI(*thisMBB, MI, DL, TII->get(PtrImmStoreOpc));
+  for (unsigned i = 0; i < X86::AddrNumOperands; ++i) {
+    if (i == X86::AddrDisp)
+      MIB.addDisp(MI->getOperand(MemOpndSlot + i), Label_Offset);
+    else
+      MIB.addOperand(MI->getOperand(MemOpndSlot + i));
+  }
+  MIB.addMBB(restoreMBB);
+  MIB.setMemRefs(MMOBegin, MMOEnd);
+  // Setup
+  MIB = BuildMI(*thisMBB, MI, DL, TII->get(X86::EH_SjLj_Setup))
+          .addMBB(restoreMBB);
+  MIB.addRegMask(RegInfo->getNoPreservedMask());
+  thisMBB->addSuccessor(mainMBB);
+  thisMBB->addSuccessor(restoreMBB);
+
+  // mainMBB:
+  //  EAX = 0
+  BuildMI(mainMBB, DL, TII->get(X86::MOV32r0), mainDstReg);
+  mainMBB->addSuccessor(sinkMBB);
+
+  // sinkMBB:
+  BuildMI(*sinkMBB, sinkMBB->begin(), DL,
+          TII->get(X86::PHI), DstReg)
+    .addReg(mainDstReg).addMBB(mainMBB)
+    .addReg(restoreDstReg).addMBB(restoreMBB);
+
+  // restoreMBB:
+  BuildMI(restoreMBB, DL, TII->get(X86::MOV32ri), restoreDstReg).addImm(1);
+  BuildMI(restoreMBB, DL, TII->get(X86::JMP_4)).addMBB(sinkMBB);
+  restoreMBB->addSuccessor(sinkMBB);
+
+  MI->eraseFromParent();
+  return sinkMBB;
+}
+
+MachineBasicBlock *
+X86TargetLowering::emitEHSjLjLongJmp(MachineInstr *MI,
+                                     MachineBasicBlock *MBB) const {
+  DebugLoc DL = MI->getDebugLoc();
+  const TargetInstrInfo *TII = getTargetMachine().getInstrInfo();
+
+  MachineFunction *MF = MBB->getParent();
+  MachineRegisterInfo &MRI = MF->getRegInfo();
+
+  // Memory Reference
+  MachineInstr::mmo_iterator MMOBegin = MI->memoperands_begin();
+  MachineInstr::mmo_iterator MMOEnd = MI->memoperands_end();
+
+  MVT PVT = getPointerTy();
+  assert((PVT == MVT::i64 || PVT == MVT::i32) &&
+         "Invalid Pointer Size!");
+
+  const TargetRegisterClass *RC =
+    (PVT == MVT::i64) ? &X86::GR64RegClass : &X86::GR32RegClass;
+  unsigned Tmp = MRI.createVirtualRegister(RC);
+  // Since FP is only updated here but NOT referenced, it's treated as GPR.
+  unsigned FP = (PVT == MVT::i64) ? X86::RBP : X86::EBP;
+  unsigned SP = RegInfo->getStackRegister();
+
+  MachineInstrBuilder MIB;
+
+  const int64_t Label_Offset = 1 * PVT.getStoreSize();
+  const int64_t SP_Offset = 2 * PVT.getStoreSize();
+
+  unsigned PtrLoadOpc = (PVT == MVT::i64) ? X86::MOV64rm : X86::MOV32rm;
+  unsigned IJmpOpc = (PVT == MVT::i64) ? X86::JMP64r : X86::JMP32r;
+
+  // Reload FP
+  MIB = BuildMI(*MBB, MI, DL, TII->get(PtrLoadOpc), FP);
+  for (unsigned i = 0; i < X86::AddrNumOperands; ++i)
+    MIB.addOperand(MI->getOperand(i));
+  MIB.setMemRefs(MMOBegin, MMOEnd);
+  // Reload IP
+  MIB = BuildMI(*MBB, MI, DL, TII->get(PtrLoadOpc), Tmp);
+  for (unsigned i = 0; i < X86::AddrNumOperands; ++i) {
+    if (i == X86::AddrDisp)
+      MIB.addDisp(MI->getOperand(i), Label_Offset);
+    else
+      MIB.addOperand(MI->getOperand(i));
+  }
+  MIB.setMemRefs(MMOBegin, MMOEnd);
+  // Reload SP
+  MIB = BuildMI(*MBB, MI, DL, TII->get(PtrLoadOpc), SP);
+  for (unsigned i = 0; i < X86::AddrNumOperands; ++i) {
+    if (i == X86::AddrDisp)
+      MIB.addDisp(MI->getOperand(i), SP_Offset);
+    else
+      MIB.addOperand(MI->getOperand(i));
+  }
+  MIB.setMemRefs(MMOBegin, MMOEnd);
+  // Jump
+  BuildMI(*MBB, MI, DL, TII->get(IJmpOpc)).addReg(Tmp);
+
+  MI->eraseFromParent();
+  return MBB;
+}
+
+MachineBasicBlock *
 X86TargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI,
                                                MachineBasicBlock *BB) const {
   switch (MI->getOpcode()) {
@@ -13427,6 +13621,14 @@ X86TargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI,
 
   case X86::VAARG_64:
     return EmitVAARG64WithCustomInserter(MI, BB);
+
+  case X86::EH_SjLj_SetJmp32:
+  case X86::EH_SjLj_SetJmp64:
+    return emitEHSjLjSetJmp(MI, BB);
+
+  case X86::EH_SjLj_LongJmp32:
+  case X86::EH_SjLj_LongJmp64:
+    return emitEHSjLjLongJmp(MI, BB);
   }
 }