[mips] Lower EH_RETURN.

Patch by Sasa Stankovic.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173862 91177308-0d34-0410-b5e6-96231b3b80d8

10 files changed, 184 insertions, 2 deletions

diff --git a/lib/Target/Mips/MipsISelLowering.cpp b/lib/Target/Mips/MipsISelLowering.cpp
index 7b8557d..cf8ed35 100644
--- a/lib/Target/Mips/MipsISelLowering.cpp
+++ b/lib/Target/Mips/MipsISelLowering.cpp
@@ -162,6 +162,7 @@ const char *MipsTargetLowering::getTargetNodeName(unsigned Opcode) const {
   case MipsISD::GPRel:             return "MipsISD::GPRel";
   case MipsISD::ThreadPointer:     return "MipsISD::ThreadPointer";
   case MipsISD::Ret:               return "MipsISD::Ret";
+  case MipsISD::EH_RETURN:         return "MipsISD::EH_RETURN";
   case MipsISD::FPBrcond:          return "MipsISD::FPBrcond";
   case MipsISD::FPCmp:             return "MipsISD::FPCmp";
   case MipsISD::CMovFP_T:          return "MipsISD::CMovFP_T";
@@ -445,6 +446,8 @@ MipsTargetLowering(MipsTargetMachine &TM)
   setOperationAction(ISD::EHSELECTION,       MVT::i32, Expand);
   setOperationAction(ISD::EHSELECTION,       MVT::i64, Expand);
 
+  setOperationAction(ISD::EH_RETURN, MVT::Other, Custom);
+
   setOperationAction(ISD::VAARG,             MVT::Other, Expand);
   setOperationAction(ISD::VACOPY,            MVT::Other, Expand);
   setOperationAction(ISD::VAEND,             MVT::Other, Expand);
@@ -1045,6 +1048,7 @@ LowerOperation(SDValue Op, SelectionDAG &DAG) const
     case ISD::FABS:               return LowerFABS(Op, DAG);
     case ISD::FRAMEADDR:          return LowerFRAMEADDR(Op, DAG);
     case ISD::RETURNADDR:         return LowerRETURNADDR(Op, DAG);
+    case ISD::EH_RETURN:          return LowerEH_RETURN(Op, DAG);
     case ISD::MEMBARRIER:         return LowerMEMBARRIER(Op, DAG);
     case ISD::ATOMIC_FENCE:       return LowerATOMIC_FENCE(Op, DAG);
     case ISD::SHL_PARTS:          return LowerShiftLeftParts(Op, DAG);
@@ -2228,6 +2232,34 @@ SDValue MipsTargetLowering::LowerRETURNADDR(SDValue Op,
   return DAG.getCopyFromReg(DAG.getEntryNode(), Op.getDebugLoc(), Reg, VT);
 }
 
+// An EH_RETURN is the result of lowering llvm.eh.return which in turn is
+// generated from __builtin_eh_return (offset, handler)
+// The effect of this is to adjust the stack pointer by "offset"
+// and then branch to "handler".
+SDValue MipsTargetLowering::LowerEH_RETURN(SDValue Op, SelectionDAG &DAG)
+                                                                     const {
+  MachineFunction &MF = DAG.getMachineFunction();
+  MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
+
+  MipsFI->setCallsEhReturn();
+  SDValue Chain     = Op.getOperand(0);
+  SDValue Offset    = Op.getOperand(1);
+  SDValue Handler   = Op.getOperand(2);
+  DebugLoc DL       = Op.getDebugLoc();
+  EVT Ty = IsN64 ? MVT::i64 : MVT::i32;
+
+  // Store stack offset in V1, store jump target in V0. Glue CopyToReg and
+  // EH_RETURN nodes, so that instructions are emitted back-to-back.
+  unsigned OffsetReg = IsN64 ? Mips::V1_64 : Mips::V1;
+  unsigned AddrReg = IsN64 ? Mips::V0_64 : Mips::V0;
+  Chain = DAG.getCopyToReg(Chain, DL, OffsetReg, Offset, SDValue());
+  Chain = DAG.getCopyToReg(Chain, DL, AddrReg, Handler, Chain.getValue(1));
+  return DAG.getNode(MipsISD::EH_RETURN, DL, MVT::Other, Chain,
+                     DAG.getRegister(OffsetReg, Ty),
+                     DAG.getRegister(AddrReg, getPointerTy()),
+                     Chain.getValue(1));
+}
+
 // TODO: set SType according to the desired memory barrier behavior.
 SDValue
 MipsTargetLowering::LowerMEMBARRIER(SDValue Op, SelectionDAG &DAG) const {
diff --git a/lib/Target/Mips/MipsISelLowering.h b/lib/Target/Mips/MipsISelLowering.h
index 053f8de..00aa282 100644
--- a/lib/Target/Mips/MipsISelLowering.h
+++ b/lib/Target/Mips/MipsISelLowering.h
@@ -65,6 +65,8 @@ namespace llvm {
       // Return
       Ret,
 
+      EH_RETURN,
+
       // MAdd/Sub nodes
       MAdd,
       MAddu,
@@ -275,6 +277,7 @@ namespace llvm {
     SDValue LowerFABS(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerFRAMEADDR(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerRETURNADDR(SDValue Op, SelectionDAG &DAG) const;
+    SDValue LowerEH_RETURN(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerMEMBARRIER(SDValue Op, SelectionDAG& DAG) const;
     SDValue LowerATOMIC_FENCE(SDValue Op, SelectionDAG& DAG) const;
     SDValue LowerShiftLeftParts(SDValue Op, SelectionDAG& DAG) const;
diff --git a/lib/Target/Mips/MipsInstrInfo.td b/lib/Target/Mips/MipsInstrInfo.td
index 74f3178..162ffb0 100644
--- a/lib/Target/Mips/MipsInstrInfo.td
+++ b/lib/Target/Mips/MipsInstrInfo.td
@@ -867,6 +867,27 @@ def TAILCALL_R : JumpFR<CPURegs, MipsTailCall>, MTLO_FM<8>, IsTailCall;
 
 def RET : RetBase<CPURegs>, MTLO_FM<8>;
 
+// Exception handling related node and instructions.
+// The conversion sequence is:
+// ISD::EH_RETURN -> MipsISD::EH_RETURN ->
+// MIPSeh_return -> (stack change + indirect branch)
+//
+// MIPSeh_return takes the place of regular return instruction
+// but takes two arguments (V1, V0) which are used for storing
+// the offset and return address respectively.
+def SDT_MipsEHRET : SDTypeProfile<0, 2, [SDTCisInt<0>, SDTCisPtrTy<1>]>;
+
+def MIPSehret : SDNode<"MipsISD::EH_RETURN", SDT_MipsEHRET,
+                      [SDNPHasChain, SDNPOptInGlue, SDNPVariadic]>;
+
+let Uses = [V0, V1], isTerminator = 1, isReturn = 1, isBarrier = 1 in {
+  def MIPSeh_return32 : MipsPseudo<(outs), (ins CPURegs:$spoff, CPURegs:$dst),
+                                [(MIPSehret CPURegs:$spoff, CPURegs:$dst)]>;
+  def MIPSeh_return64 : MipsPseudo<(outs), (ins CPU64Regs:$spoff,
+                                                CPU64Regs:$dst),
+                                [(MIPSehret CPU64Regs:$spoff, CPU64Regs:$dst)]>;
+}
+
 /// Multiply and Divide Instructions.
 def MULT  : Mult<"mult", IIImul, CPURegsOpnd, [HI, LO]>, MULT_FM<0, 0x18>;
 def MULTu : Mult<"multu", IIImul, CPURegsOpnd, [HI, LO]>, MULT_FM<0, 0x19>;
diff --git a/lib/Target/Mips/MipsMachineFunction.cpp b/lib/Target/Mips/MipsMachineFunction.cpp
index 0c71596..59b23f7 100644
--- a/lib/Target/Mips/MipsMachineFunction.cpp
+++ b/lib/Target/Mips/MipsMachineFunction.cpp
@@ -56,4 +56,20 @@ unsigned MipsFunctionInfo::getMips16SPAliasReg() {
   return Mips16SPAliasReg = MF.getRegInfo().createVirtualRegister(RC);
 }
 
+void MipsFunctionInfo::createEhDataRegsFI() {
+  for (int I = 0; I < 4; ++I) {
+    const MipsSubtarget &ST = MF.getTarget().getSubtarget<MipsSubtarget>();
+    const TargetRegisterClass *RC = ST.isABI_N64() ?
+        &Mips::CPU64RegsRegClass : &Mips::CPURegsRegClass;
+
+    EhDataRegFI[I] = MF.getFrameInfo()->CreateStackObject(RC->getSize(),
+        RC->getAlignment(), false);
+  }
+}
+
+bool MipsFunctionInfo::isEhDataRegFI(int FI) const {
+  return CallsEhReturn && (FI == EhDataRegFI[0] || FI == EhDataRegFI[1]
+                        || FI == EhDataRegFI[2] || FI == EhDataRegFI[3]);
+}
+
 void MipsFunctionInfo::anchor() { }
diff --git a/lib/Target/Mips/MipsMachineFunction.h b/lib/Target/Mips/MipsMachineFunction.h
index eb6e1cf..b05b348 100644
--- a/lib/Target/Mips/MipsMachineFunction.h
+++ b/lib/Target/Mips/MipsMachineFunction.h
@@ -53,10 +53,16 @@ class MipsFunctionInfo : public MachineFunctionInfo {
   /// Size of incoming argument area.
   unsigned IncomingArgSize;
 
+  /// CallsEhReturn - Whether the function calls llvm.eh.return.
+  bool CallsEhReturn;
+
+  /// Frame objects for spilling eh data registers.
+  int EhDataRegFI[4];
+
 public:
   MipsFunctionInfo(MachineFunction& MF)
    : MF(MF), SRetReturnReg(0), GlobalBaseReg(0), Mips16SPAliasReg(0),
-     VarArgsFrameIndex(0)
+     VarArgsFrameIndex(0), CallsEhReturn(false)
   {}
 
   unsigned getSRetReturnReg() const { return SRetReturnReg; }
@@ -78,6 +84,14 @@ public:
   }
 
   unsigned getIncomingArgSize() const { return IncomingArgSize; }
+
+  bool callsEhReturn() const { return CallsEhReturn; }
+  void setCallsEhReturn() { CallsEhReturn = true; }
+
+  void createEhDataRegsFI();
+  int getEhDataRegFI(unsigned Reg) const { return EhDataRegFI[Reg]; }
+  bool isEhDataRegFI(int FI) const;
+
 };
 
 } // end of namespace llvm
diff --git a/lib/Target/Mips/MipsSEFrameLowering.cpp b/lib/Target/Mips/MipsSEFrameLowering.cpp
index 60b1233..e5ecf2c 100644
--- a/lib/Target/Mips/MipsSEFrameLowering.cpp
+++ b/lib/Target/Mips/MipsSEFrameLowering.cpp
@@ -29,9 +29,21 @@
 
 using namespace llvm;
 
+unsigned MipsSEFrameLowering::ehDataReg(unsigned I) const {
+  static const unsigned EhDataReg[] = {
+    Mips::A0, Mips::A1, Mips::A2, Mips::A3
+  };
+  static const unsigned EhDataReg64[] = {
+    Mips::A0_64, Mips::A1_64, Mips::A2_64, Mips::A3_64
+  };
+
+  return STI.isABI_N64() ? EhDataReg64[I] : EhDataReg[I];
+}
+
 void MipsSEFrameLowering::emitPrologue(MachineFunction &MF) const {
   MachineBasicBlock &MBB   = MF.front();
   MachineFrameInfo *MFI    = MF.getFrameInfo();
+  MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
   const MipsRegisterInfo *RegInfo =
     static_cast<const MipsRegisterInfo*>(MF.getTarget().getRegisterInfo());
   const MipsSEInstrInfo &TII =
@@ -105,6 +117,30 @@ void MipsSEFrameLowering::emitPrologue(MachineFunction &MF) const {
     }
   }
 
+  if (MipsFI->callsEhReturn()) {
+    const TargetRegisterClass *RC = STI.isABI_N64() ?
+        &Mips::CPU64RegsRegClass : &Mips::CPURegsRegClass;
+
+    // Insert instructions that spill eh data registers.
+    for (int I = 0; I < 4; ++I) {
+      if (!MBB.isLiveIn(ehDataReg(I)))
+        MBB.addLiveIn(ehDataReg(I));
+      TII.storeRegToStackSlot(MBB, MBBI, ehDataReg(I), false,
+                              MipsFI->getEhDataRegFI(I), RC, RegInfo);
+    }
+
+    // Emit .cfi_offset directives for eh data registers.
+    MCSymbol *CSLabel2 = MMI.getContext().CreateTempSymbol();
+    BuildMI(MBB, MBBI, dl,
+            TII.get(TargetOpcode::PROLOG_LABEL)).addSym(CSLabel2);
+    for (int I = 0; I < 4; ++I) {
+      int64_t Offset = MFI->getObjectOffset(MipsFI->getEhDataRegFI(I));
+      DstML = MachineLocation(MachineLocation::VirtualFP, Offset);
+      SrcML = MachineLocation(ehDataReg(I));
+      Moves.push_back(MachineMove(CSLabel2, DstML, SrcML));
+    }
+  }
+
   // if framepointer enabled, set it to point to the stack pointer.
   if (hasFP(MF)) {
     // Insert instruction "move $fp, $sp" at this location.
@@ -124,6 +160,9 @@ void MipsSEFrameLowering::emitEpilogue(MachineFunction &MF,
                                        MachineBasicBlock &MBB) const {
   MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
   MachineFrameInfo *MFI            = MF.getFrameInfo();
+  MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
+  const MipsRegisterInfo *RegInfo =
+    static_cast<const MipsRegisterInfo*>(MF.getTarget().getRegisterInfo());
   const MipsSEInstrInfo &TII =
     *static_cast<const MipsSEInstrInfo*>(MF.getTarget().getInstrInfo());
   DebugLoc dl = MBBI->getDebugLoc();
@@ -144,6 +183,22 @@ void MipsSEFrameLowering::emitEpilogue(MachineFunction &MF,
     BuildMI(MBB, I, dl, TII.get(ADDu), SP).addReg(FP).addReg(ZERO);
   }
 
+  if (MipsFI->callsEhReturn()) {
+    const TargetRegisterClass *RC = STI.isABI_N64() ?
+        &Mips::CPU64RegsRegClass : &Mips::CPURegsRegClass;
+
+    // Find first instruction that restores a callee-saved register.
+    MachineBasicBlock::iterator I = MBBI;
+    for (unsigned i = 0; i < MFI->getCalleeSavedInfo().size(); ++i)
+      --I;
+
+    // Insert instructions that restore eh data registers.
+    for (int J = 0; J < 4; ++J) {
+      TII.loadRegFromStackSlot(MBB, I, ehDataReg(J), MipsFI->getEhDataRegFI(J),
+                               RC, RegInfo);
+    }
+  }
+
   // Get the number of bytes from FrameInfo
   uint64_t StackSize = MFI->getStackSize();
 
@@ -198,12 +253,17 @@ void MipsSEFrameLowering::
 processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
                                      RegScavenger *RS) const {
   MachineRegisterInfo &MRI = MF.getRegInfo();
+  MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
   unsigned FP = STI.isABI_N64() ? Mips::FP_64 : Mips::FP;
 
   // Mark $fp as used if function has dedicated frame pointer.
   if (hasFP(MF))
     MRI.setPhysRegUsed(FP);
 
+  // Create spill slots for eh data registers if function calls eh_return.
+  if (MipsFI->callsEhReturn())
+    MipsFI->createEhDataRegsFI();
+
   // Set scavenging frame index if necessary.
   uint64_t MaxSPOffset = MF.getInfo<MipsFunctionInfo>()->getIncomingArgSize() +
     estimateStackSize(MF);
diff --git a/lib/Target/Mips/MipsSEFrameLowering.h b/lib/Target/Mips/MipsSEFrameLowering.h
index 6481a0a..9b04ee9 100644
--- a/lib/Target/Mips/MipsSEFrameLowering.h
+++ b/lib/Target/Mips/MipsSEFrameLowering.h
@@ -37,6 +37,7 @@ public:
 
   void processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
                                             RegScavenger *RS) const;
+  unsigned ehDataReg(unsigned I) const;
 };
 
 } // End llvm namespace
diff --git a/lib/Target/Mips/MipsSEInstrInfo.cpp b/lib/Target/Mips/MipsSEInstrInfo.cpp
index cd8f9f4..a9809ef 100644
--- a/lib/Target/Mips/MipsSEInstrInfo.cpp
+++ b/lib/Target/Mips/MipsSEInstrInfo.cpp
@@ -220,6 +220,10 @@ bool MipsSEInstrInfo::expandPostRAPseudo(MachineBasicBlock::iterator MI) const {
   case Mips::ExtractElementF64:
     ExpandExtractElementF64(MBB, MI);
     break;
+  case Mips::MIPSeh_return32:
+  case Mips::MIPSeh_return64:
+    ExpandEhReturn(MBB, MI);
+    break;
   }
 
   MBB.erase(MI);
@@ -356,6 +360,31 @@ void MipsSEInstrInfo::ExpandBuildPairF64(MachineBasicBlock &MBB,
     .addReg(HiReg);
 }
 
+void MipsSEInstrInfo::ExpandEhReturn(MachineBasicBlock &MBB,
+                                     MachineBasicBlock::iterator I) const {
+  // This pseudo instruction is generated as part of the lowering of
+  // ISD::EH_RETURN. We convert it to a stack increment by OffsetReg, and
+  // indirect jump to TargetReg
+  const MipsSubtarget &STI = TM.getSubtarget<MipsSubtarget>();
+  unsigned ADDU = STI.isABI_N64() ? Mips::DADDu : Mips::ADDu;
+  unsigned OR = STI.isABI_N64() ? Mips::OR64 : Mips::OR;
+  unsigned JR = STI.isABI_N64() ? Mips::JR64 : Mips::JR;
+  unsigned SP = STI.isABI_N64() ? Mips::SP_64 : Mips::SP;
+  unsigned RA = STI.isABI_N64() ? Mips::RA_64 : Mips::RA;
+  unsigned ZERO = STI.isABI_N64() ? Mips::ZERO_64 : Mips::ZERO;
+  unsigned OffsetReg = I->getOperand(0).getReg();
+  unsigned TargetReg = I->getOperand(1).getReg();
+
+  // or   $ra, $v0, $zero
+  // addu $sp, $sp, $v1
+  // jr   $ra
+  BuildMI(MBB, I, I->getDebugLoc(), TM.getInstrInfo()->get(OR), RA)
+      .addReg(TargetReg).addReg(ZERO);
+  BuildMI(MBB, I, I->getDebugLoc(), TM.getInstrInfo()->get(ADDU), SP)
+      .addReg(SP).addReg(OffsetReg);
+  BuildMI(MBB, I, I->getDebugLoc(), TM.getInstrInfo()->get(JR)).addReg(RA);
+}
+
 const MipsInstrInfo *llvm::createMipsSEInstrInfo(MipsTargetMachine &TM) {
   return new MipsSEInstrInfo(TM);
 }
diff --git a/lib/Target/Mips/MipsSEInstrInfo.h b/lib/Target/Mips/MipsSEInstrInfo.h
index 55b78b2..3e22b33 100644
--- a/lib/Target/Mips/MipsSEInstrInfo.h
+++ b/lib/Target/Mips/MipsSEInstrInfo.h
@@ -85,6 +85,8 @@ private:
                                MachineBasicBlock::iterator I) const;
   void ExpandBuildPairF64(MachineBasicBlock &MBB,
                           MachineBasicBlock::iterator I) const;
+  void ExpandEhReturn(MachineBasicBlock &MBB,
+                      MachineBasicBlock::iterator I) const;
 };
 
 }
diff --git a/lib/Target/Mips/MipsSERegisterInfo.cpp b/lib/Target/Mips/MipsSERegisterInfo.cpp
index abeab7b..0c0a1a3 100644
--- a/lib/Target/Mips/MipsSERegisterInfo.cpp
+++ b/lib/Target/Mips/MipsSERegisterInfo.cpp
@@ -83,6 +83,7 @@ void MipsSERegisterInfo::eliminateFI(MachineBasicBlock::iterator II,
   MachineInstr &MI = *II;
   MachineFunction &MF = *MI.getParent()->getParent();
   MachineFrameInfo *MFI = MF.getFrameInfo();
+  MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
 
   const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
   int MinCSFI = 0;
@@ -93,15 +94,18 @@ void MipsSERegisterInfo::eliminateFI(MachineBasicBlock::iterator II,
     MaxCSFI = CSI[CSI.size() - 1].getFrameIdx();
   }
 
+  bool EhDataRegFI = MipsFI->isEhDataRegFI(FrameIndex);
+
   // The following stack frame objects are always referenced relative to $sp:
   //  1. Outgoing arguments.
   //  2. Pointer to dynamically allocated stack space.
   //  3. Locations for callee-saved registers.
+  //  4. Locations for eh data registers.
   // Everything else is referenced relative to whatever register
   // getFrameRegister() returns.
   unsigned FrameReg;
 
-  if (FrameIndex >= MinCSFI && FrameIndex <= MaxCSFI)
+  if ((FrameIndex >= MinCSFI && FrameIndex <= MaxCSFI) || EhDataRegFI)
     FrameReg = Subtarget.isABI_N64() ? Mips::SP_64 : Mips::SP;
   else
     FrameReg = getFrameRegister(MF);