[mips] Interrupt attribute support for mips32r2+.

[sdardis]

Summary

This patch adds support for using the "interrupt" attribute on Mips
for interrupt handling functions. At this time only mips32r2+ with the
o32 ABI with the static relocation model is supported. Unsupported
configurations will be rejected

[sdardis]

Fix for MipsInstrInfo.td which wasn't tested properly.

[vkalintiris]

I added some comments and few minor nits.

Also, I suppose that functions with the "interrupt" attribute should not take any arguments. If this is the case then we should report an error.

lib/Target/Mips/MipsAsmPrinter.cpp

200–203 ↗

(On Diff #28664)

We don't need this special case if we derive the ERet def from the PseudoInstExpansion class too.

lib/Target/Mips/MipsAsmPrinter.h

50 ↗

(On Diff #28664)

Nit: Fix indentation.

lib/Target/Mips/MipsMachineFunction.h

148 ↗

(On Diff #28664)

Nit: Rename ISR to IsISR.

lib/Target/Mips/MipsRegisterInfo.cpp

90–98 ↗

(On Diff #28664)

Nit: Can we replace nested if/else with ternary operator?

lib/Target/Mips/MipsSEFrameLowering.cpp

528–529 ↗

(On Diff #28664)

Nit: Fix indentation (You'll have to consult clang-format for that).

532–535 ↗

(On Diff #28664)

If you don't use the sub-classed MipsSEInstrInfo, then the casts are unnecessary (likewise for emitInterruptEpilogueStub).

546–550 ↗

(On Diff #28664)

We are in the StandardEncoding (SE) sub-class. STI.inMips16Mode() will always return false. Also, in the commit message you mention that we support the interrupt attribute for MIPS32. However, here you test for MIPS32R2.

606–627 ↗

(On Diff #28664)

We can use StringSwitch here and just assert on InsSize's value.

738–739 ↗

(On Diff #28664)

Nit: Missing new line.

768–785 ↗

(On Diff #28664)

We can avoid the duplicate BuildMIs by figuring out the opcode and the register first. We can use MipsABIInfo's API here too.

lib/Target/Mips/MipsSEInstrInfo.cpp

192–204 ↗

(On Diff #28664)

It would be nice if we could find a test that hits this code path.

Also, I believe that the "interrupt" attribute check and the BuildMIs, should happen below (lines 233-240), in order to keep the function's "form" consistent.

258 ↗

(On Diff #28664)

Nit: reqIndirectLoad -> ReqIndirectLoad

258–260 ↗

(On Diff #28664)

Nit: clang-format places the logical operators && and || at the end of the line.

303–314 ↗

(On Diff #28664)

We can simplify this by using MipsABIInfo::ArePtrs64bit().

504 ↗

(On Diff #28664)

Nit: Fix indentation.

lib/Target/Mips/MipsSERegisterInfo.cpp

129 ↗

(On Diff #28664)

Nit: Rename ISRRegFI -> IsISRRegFI.

test/CodeGen/Mips/interrupt-attr-fail.ll

1 ↗

(On Diff #28664)

The default prefix is CHECK. You don't have to specify it explicitly (likewise for interrupt-attr.ll).

test/CodeGen/Mips/interrupt-attr.ll

3–4 ↗

(On Diff #28664)

Use CHECK-LABEL at the entry point of each function.

5–11 ↗

(On Diff #28664)

We should match the offsets of the store instructions in the prologue with the offsets of the load instructions in the epilogue (at least for the interrupt-specific registers).

[sdardis]

Comments addressed.

Now errors out for mips16 and when functions with the interrupt attribute have arguments. Additional XFAIL test for mips64r6.

The codepath for saving/restoring hi/lo is tested with interrupt-attr.ll, specifically the isr_sw0 function.

Thanks.

[vkalintiris]

This LGTM. However, we need to clang-format the patch. Do you have commit access? If not then I can format it and commit it by myself.

[sdardis]

I don't have commit access. Thanks.

llvm/trunk/lib/Target/Mips/MipsCallingConv.td

 
 def CSR_N64 : CalleeSavedRegs<(add (sequence "D%u_64", 31, 24), RA_64, FP_64,
                                    GP_64, (sequence "S%u_64", 7, 0))>;
 
 def CSR_Mips16RetHelper :
   CalleeSavedRegs<(add V0, V1, FP,
                    (sequence "A%u", 3, 0), (sequence "S%u", 7, 0),
                    (sequence "D%u", 15, 10))>;
+
+def CSR_Interrupt_32R6 : CalleeSavedRegs<(add (sequence "A%u", 3, 0),
+                                              (sequence "S%u", 7, 0),
+                                              (sequence "V%u", 1, 0),
+                                              (sequence "T%u", 9, 0),
+                                              RA, FP, GP, AT)>;
+
+def CSR_Interrupt_32 : CalleeSavedRegs<(add (sequence "A%u", 3, 0),
+                                            (sequence "S%u", 7, 0),
+                                            (sequence "V%u", 1, 0),
+                                            (sequence "T%u", 9, 0),
+                                            RA, FP, GP, AT, LO0, HI0)>;
+
+def CSR_Interrupt_64R6 : CalleeSavedRegs<(add (sequence "A%u_64", 3, 0),
+                                              (sequence "V%u_64", 1, 0),
+                                              (sequence "S%u_64", 7, 0),
+                                              (sequence "T%u_64", 9, 0),
+                                              RA_64, FP_64, GP_64, AT_64)>;
+
+def CSR_Interrupt_64 : CalleeSavedRegs<(add (sequence "A%u_64", 3, 0),
+                                            (sequence "S%u_64", 7, 0),
+                                            (sequence "T%u_64", 9, 0),
+                                            (sequence "V%u_64", 1, 0),
+                                            RA_64, FP_64, GP_64, AT_64,
+                                            LO0_64, HI0_64)>;

llvm/trunk/lib/Target/Mips/MipsISelLowering.h

enum NodeType : unsigned {
       CMovFP_F,
 
       // FP-to-int truncation node.
       TruncIntFP,
 
       // Return
       Ret,
 
+      // Interrupt, exception, error trap Return
+      ERet,
+
+      // Software Exception Return.
       EH_RETURN,
 
       // Node used to extract integer from accumulator.
       MFHI,
       MFLO,
 
       // Node used to insert integers to accumulator.
       MTLOHI,
bool CanLowerReturn(CallingConv::ID CallConv, MachineFunction &MF,
                         LLVMContext &Context) const override;
 
     SDValue LowerReturn(SDValue Chain,
                         CallingConv::ID CallConv, bool isVarArg,
                         const SmallVectorImpl<ISD::OutputArg> &Outs,
                         const SmallVectorImpl<SDValue> &OutVals,
                         SDLoc dl, SelectionDAG &DAG) const override;
 
+    SDValue LowerInterruptReturn(SmallVectorImpl<SDValue> &RetOps, SDLoc DL,
+                                 SelectionDAG &DAG) const;
+
     bool shouldSignExtendTypeInLibCall(EVT Type, bool IsSigned) const override;
 
     // Inline asm support
     ConstraintType getConstraintType(StringRef Constraint) const override;
 
     /// Examine constraint string and operand type and determine a weight value.
     /// The operand object must already have been set up with the operand type.
     ConstraintWeight getSingleConstraintMatchWeight(

llvm/trunk/lib/Target/Mips/MipsISelLowering.cpp

const char *MipsTargetLowering::getTargetNodeName(unsigned Opcode) const {
   case MipsISD::FIRST_NUMBER:      break;
   case MipsISD::JmpLink:           return "MipsISD::JmpLink";
   case MipsISD::TailCall:          return "MipsISD::TailCall";
   case MipsISD::Hi:                return "MipsISD::Hi";
   case MipsISD::Lo:                return "MipsISD::Lo";
   case MipsISD::GPRel:             return "MipsISD::GPRel";
   case MipsISD::ThreadPointer:     return "MipsISD::ThreadPointer";
   case MipsISD::Ret:               return "MipsISD::Ret";
+  case MipsISD::ERet:              return "MipsISD::ERet";
   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";
   case MipsISD::CMovFP_F:          return "MipsISD::CMovFP_F";
   case MipsISD::TruncIntFP:        return "MipsISD::TruncIntFP";
   case MipsISD::MFHI:              return "MipsISD::MFHI";
   case MipsISD::MFLO:              return "MipsISD::MFLO";
MipsTargetLowering::LowerFormalArguments(SDValue Chain,
   // Used with vargs to acumulate store chains.
   std::vector<SDValue> OutChains;
 
   // Assign locations to all of the incoming arguments.
   SmallVector<CCValAssign, 16> ArgLocs;
   MipsCCState CCInfo(CallConv, IsVarArg, DAG.getMachineFunction(), ArgLocs,
                      *DAG.getContext());
   CCInfo.AllocateStack(ABI.GetCalleeAllocdArgSizeInBytes(CallConv), 1);
-  Function::const_arg_iterator FuncArg =
-    DAG.getMachineFunction().getFunction()->arg_begin();
+  const Function *Func = DAG.getMachineFunction().getFunction();
+  Function::const_arg_iterator FuncArg = Func->arg_begin();
+
+  if (Func->hasFnAttribute("interrupt"))
+    assert(Func->arg_empty() &&
+           "Functions with the interrupt attribute cannot have arguments!");
 
   CCInfo.AnalyzeFormalArguments(Ins, CC_Mips_FixedArg);
   MipsFI->setFormalArgInfo(CCInfo.getNextStackOffset(),
                            CCInfo.getInRegsParamsCount() > 0);
 
   unsigned CurArgIdx = 0;
   CCInfo.rewindByValRegsInfo();
 
MipsTargetLowering::shouldSignExtendTypeInLibCall(EVT Type, bool IsSigned) const {
   if (Subtarget.hasMips3() && Subtarget.useSoftFloat()) {
     if (Type == MVT::i32)
       return true;
   }
   return IsSigned;
 }
 
 SDValue
-MipsTargetLowering::LowerReturn(SDValue Chain,
-                                CallingConv::ID CallConv, bool IsVarArg,
+MipsTargetLowering::LowerInterruptReturn(SmallVectorImpl<SDValue> &RetOps,
+                                         SDLoc DL, SelectionDAG &DAG) const {
+
+  MachineFunction &MF = DAG.getMachineFunction();
+  MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
+
+  MipsFI->setISR();
+
+  return DAG.getNode(MipsISD::ERet, DL, MVT::Other, RetOps);
+}
+
+SDValue
+MipsTargetLowering::LowerReturn(SDValue Chain, CallingConv::ID CallConv,
+                                bool IsVarArg,
                                 const SmallVectorImpl<ISD::OutputArg> &Outs,
                                 const SmallVectorImpl<SDValue> &OutVals,
                                 SDLoc DL, SelectionDAG &DAG) const {
   // CCValAssign - represent the assignment of
   // the return value to a location
   SmallVector<CCValAssign, 16> RVLocs;
   MachineFunction &MF = DAG.getMachineFunction();
 
MipsTargetLowering::LowerReturn(SDValue Chain, CallingConv::ID CallConv,
   }
 
   RetOps[0] = Chain;  // Update chain.
 
   // Add the flag if we have it.
   if (Flag.getNode())
     RetOps.push_back(Flag);
 
-  // Return on Mips is always a "jr $ra"
+  // ISRs must use "eret".
+  if (DAG.getMachineFunction().getFunction()->hasFnAttribute("interrupt"))
+    return LowerInterruptReturn(RetOps, DL, DAG);
+
+  // Standard return on Mips is a "jr $ra"
   return DAG.getNode(MipsISD::Ret, DL, MVT::Other, RetOps);
 }
 
 //===----------------------------------------------------------------------===//
 //                           Mips Inline Assembly Support
 //===----------------------------------------------------------------------===//
 
 /// getConstraintType - Given a constraint letter, return the type of

llvm/trunk/lib/Target/Mips/MipsInstrInfo.td

 
 // Thread pointer
 def MipsThreadPointer: SDNode<"MipsISD::ThreadPointer", SDT_MipsThreadPointer>;
 
 // Return
 def MipsRet : SDNode<"MipsISD::Ret", SDTNone,
                      [SDNPHasChain, SDNPOptInGlue, SDNPVariadic]>;
 
+def MipsERet : SDNode<"MipsISD::ERet", SDTNone,
+                      [SDNPHasChain, SDNPOptInGlue, SDNPSideEffect]>;
+
 // These are target-independent nodes, but have target-specific formats.
 def callseq_start : SDNode<"ISD::CALLSEQ_START", SDT_MipsCallSeqStart,
                            [SDNPHasChain, SDNPSideEffect, SDNPOutGlue]>;
 def callseq_end   : SDNode<"ISD::CALLSEQ_END", SDT_MipsCallSeqEnd,
                            [SDNPHasChain, SDNPSideEffect,
                             SDNPOptInGlue, SDNPOutGlue]>;
 
 // Nodes used to extract LO/HI registers.

 //===----------------------------------------------------------------------===//
 // Pseudo instructions
 //===----------------------------------------------------------------------===//
 
 // Return RA.
 let isReturn=1, isTerminator=1, hasDelaySlot=1, isBarrier=1, hasCtrlDep=1 in
 def RetRA : PseudoSE<(outs), (ins), [(MipsRet)]>;
 
+let isReturn=1, isTerminator=1, isBarrier=1, hasCtrlDep=1, hasSideEffects=1 in
+def ERet : PseudoSE<(outs), (ins), [(MipsERet)]>;
+
 let Defs = [SP], Uses = [SP], hasSideEffects = 1 in {
 def ADJCALLSTACKDOWN : MipsPseudo<(outs), (ins i32imm:$amt),
                                   [(callseq_start timm:$amt)]>;
 def ADJCALLSTACKUP   : MipsPseudo<(outs), (ins i32imm:$amt1, i32imm:$amt2),
                                   [(callseq_end timm:$amt1, timm:$amt2)]>;
 }
 
 let usesCustomInserter = 1 in {

llvm/trunk/lib/Target/Mips/MipsMachineFunction.h

 namespace llvm {
 
 /// MipsFunctionInfo - This class is derived from MachineFunction private
 /// Mips target-specific information for each MachineFunction.
 class MipsFunctionInfo : public MachineFunctionInfo {
 public:
   MipsFunctionInfo(MachineFunction &MF)
       : MF(MF), SRetReturnReg(0), GlobalBaseReg(0), Mips16SPAliasReg(0),
-        VarArgsFrameIndex(0), CallsEhReturn(false), SaveS2(false),
+        VarArgsFrameIndex(0), CallsEhReturn(false), IsISR(false), SaveS2(false),
         MoveF64ViaSpillFI(-1) {}
 
   ~MipsFunctionInfo();
 
   unsigned getSRetReturnReg() const { return SRetReturnReg; }
   void setSRetReturnReg(unsigned Reg) { SRetReturnReg = Reg; }
 
   bool globalBaseRegSet() const;
public:
   void createEhDataRegsFI();
   int getEhDataRegFI(unsigned Reg) const { return EhDataRegFI[Reg]; }
   bool isEhDataRegFI(int FI) const;
 
   /// Create a MachinePointerInfo that has an ExternalSymbolPseudoSourceValue
   /// object representing a GOT entry for an external function.
   MachinePointerInfo callPtrInfo(const char *ES);
 
+  // Functions with the "interrupt" attribute require special prologues,
+  // epilogues and additional spill slots.
+  bool isISR() const { return IsISR; }
+  void setISR() { IsISR = true; }
+  void createISRRegFI();
+  int getISRRegFI(unsigned Reg) const { return ISRDataRegFI[Reg]; }
+  bool isISRRegFI(int FI) const;
+
   /// Create a MachinePointerInfo that has a GlobalValuePseudoSourceValue object
   /// representing a GOT entry for a global function.
   MachinePointerInfo callPtrInfo(const GlobalValue *GV);
 
   void setSaveS2() { SaveS2 = true; }
   bool hasSaveS2() const { return SaveS2; }
 
   int getMoveF64ViaSpillFI(const TargetRegisterClass *RC);
private:
   unsigned IncomingArgSize;
 
   /// CallsEhReturn - Whether the function calls llvm.eh.return.
   bool CallsEhReturn;
 
   /// Frame objects for spilling eh data registers.
   int EhDataRegFI[4];
 
+  /// ISR - Whether the function is an Interrupt Service Routine.
+  bool IsISR;
+
+  /// Frame objects for spilling C0_STATUS, C0_EPC
+  int ISRDataRegFI[2];
+
   // saveS2
   bool SaveS2;
 
   /// FrameIndex for expanding BuildPairF64 nodes to spill and reload when the
   /// O32 FPXX ABI is enabled. -1 is used to denote invalid index.
   int MoveF64ViaSpillFI;
 };
 
 } // end of namespace llvm
 
 #endif

llvm/trunk/lib/Target/Mips/MipsMachineFunction.cpp

const TargetRegisterClass *RC =
             ? &Mips::GPR64RegClass
             : &Mips::GPR32RegClass;
 
     EhDataRegFI[I] = MF.getFrameInfo()->CreateStackObject(RC->getSize(),
         RC->getAlignment(), false);
   }
 }
 
+void MipsFunctionInfo::createISRRegFI() {
+  // ISRs require spill slots for Status & ErrorPC Coprocessor 0 registers.
+  // The current implementation only supports Mips32r2+ not Mips64rX. Status
+  // is always 32 bits, ErrorPC is 32 or 64 bits dependant on architecture,
+  // however Mips32r2+ is the supported architecture.
+  const TargetRegisterClass *RC = &Mips::GPR32RegClass;
+
+  for (int I = 0; I < 2; ++I)
+    ISRDataRegFI[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]);
 }
 
+bool MipsFunctionInfo::isISRRegFI(int FI) const {
+  return IsISR && (FI == ISRDataRegFI[0] || FI == ISRDataRegFI[1]);
+}
 MachinePointerInfo MipsFunctionInfo::callPtrInfo(const char *ES) {
   return MachinePointerInfo(MF.getPSVManager().getExternalSymbolCallEntry(ES));
 }
 
 MachinePointerInfo MipsFunctionInfo::callPtrInfo(const GlobalValue *GV) {
   return MachinePointerInfo(MF.getPSVManager().getGlobalValueCallEntry(GV));
 }
 

llvm/trunk/lib/Target/Mips/MipsRegisterInfo.cpp

 //===----------------------------------------------------------------------===//
 // Callee Saved Registers methods
 //===----------------------------------------------------------------------===//
 
 /// Mips Callee Saved Registers
 const MCPhysReg *
 MipsRegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
   const MipsSubtarget &Subtarget = MF->getSubtarget<MipsSubtarget>();
+  const Function *F = MF->getFunction();
+  if (F->hasFnAttribute("interrupt")) {
+    if (Subtarget.hasMips64())
+      return Subtarget.hasMips64r6() ? CSR_Interrupt_64R6_SaveList
+                                     : CSR_Interrupt_64_SaveList;
+    else
+      return Subtarget.hasMips32r6() ? CSR_Interrupt_32R6_SaveList
+                                     : CSR_Interrupt_32_SaveList;
+  }
+
   if (Subtarget.isSingleFloat())
     return CSR_SingleFloatOnly_SaveList;
 
   if (Subtarget.isABI_N64())
     return CSR_N64_SaveList;
 
   if (Subtarget.isABI_N32())
     return CSR_N32_SaveList;

llvm/trunk/lib/Target/Mips/MipsSEFrameLowering.h

bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
                                  const std::vector<CalleeSavedInfo> &CSI,
                                  const TargetRegisterInfo *TRI) const override;
 
   bool hasReservedCallFrame(const MachineFunction &MF) const override;
 
   void determineCalleeSaves(MachineFunction &MF, BitVector &SavedRegs,
                             RegScavenger *RS) const override;
   unsigned ehDataReg(unsigned I) const;
-};
 
+private:
+  void emitInterruptEpilogueStub(MachineFunction &MF,
+                                 MachineBasicBlock &MBB) const;
+  void emitInterruptPrologueStub(MachineFunction &MF,
+                                 MachineBasicBlock &MBB) const;
+};
 } // End llvm namespace
 
 #endif

llvm/trunk/lib/Target/Mips/MipsSEFrameLowering.cpp

 //===----------------------------------------------------------------------===//
 
 #include "MipsSEFrameLowering.h"
 #include "MCTargetDesc/MipsBaseInfo.h"
 #include "MipsAnalyzeImmediate.h"
 #include "MipsMachineFunction.h"
 #include "MipsSEInstrInfo.h"
 #include "MipsSubtarget.h"
+#include "llvm/ADT/StringSwitch.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/RegisterScavenging.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/Function.h"
void MipsSEFrameLowering::emitPrologue(MachineFunction &MF,
   TII.adjustStackPtr(SP, -StackSize, MBB, MBBI);
 
   // emit ".cfi_def_cfa_offset StackSize"
   unsigned CFIIndex = MMI.addFrameInst(
       MCCFIInstruction::createDefCfaOffset(nullptr, -StackSize));
   BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
       .addCFIIndex(CFIIndex);
 
+  if (MF.getFunction()->hasFnAttribute("interrupt"))
+    emitInterruptPrologueStub(MF, MBB);
+
   const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
 
   if (CSI.size()) {
     // Find the instruction past the last instruction that saves a callee-saved
     // register to the stack.
     for (unsigned i = 0; i < CSI.size(); ++i)
       ++MBBI;
 
if (RegInfo.needsStackRealignment(MF)) {
         BuildMI(MBB, MBBI, dl, TII.get(MOVE), BP)
           .addReg(SP)
           .addReg(ZERO);
       }
     }
   }
 }
 
+void MipsSEFrameLowering::emitInterruptPrologueStub(
+    MachineFunction &MF, MachineBasicBlock &MBB) const {
+
+  MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
+  MachineBasicBlock::iterator MBBI = MBB.begin();
+  DebugLoc DL = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
+
+  // Report an error the target doesn't support Mips32r2 or later.
+  // The epilogue relies on the use of the "ehb" to clear execution
+  // hazards. Pre R2 Mips relies on an implementation defined number
+  // of "ssnop"s to clear the execution hazard. Support for ssnop hazard
+  // clearing is not provided so reject that configuration.
+  if (!STI.hasMips32r2())
+    report_fatal_error(
+        "\"interrupt\" attribute is not supported on pre-r2 MIPS or"
+        "Mips16 targets.");
+
+  // The GP register contains the "user" value, so we cannot perform
+  // any gp relative loads until we restore the "kernel" or "system" gp
+  // value. Until support is written we shall only accept the static
+  // relocation model.
+  if ((STI.getRelocationModel() != Reloc::Static))
+    report_fatal_error("\"interrupt\" attribute is only supported for the "
+                       "static relocation model on MIPS at the present time.");
+
+  if (!STI.isABI_O32() || STI.hasMips64())
+    report_fatal_error("\"interrupt\" attribute is only supported for the "
+                       "O32 ABI on MIPS32r2+ at the present time.");
+
+  // Perform ISR handling like GCC
+  StringRef IntKind =
+      MF.getFunction()->getFnAttribute("interrupt").getValueAsString();
+  const TargetRegisterClass *PtrRC = &Mips::GPR32RegClass;
+
+  // EIC interrupt handling needs to read the Cause register to disable
+  // interrupts.
+  if (IntKind == "eic") {
+    // Coprocessor registers are always live per se.
+    MBB.addLiveIn(Mips::COP013);
+    BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::MFC0), Mips::K0)
+        .addReg(Mips::COP013)
+        .addImm(0)
+        .setMIFlag(MachineInstr::FrameSetup);
+
+    BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::EXT), Mips::K0)
+        .addReg(Mips::K0)
+        .addImm(10)
+        .addImm(6)
+        .setMIFlag(MachineInstr::FrameSetup);
+  }
+
+  // Fetch and spill EPC
+  MBB.addLiveIn(Mips::COP014);
+  BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::MFC0), Mips::K1)
+      .addReg(Mips::COP014)
+      .addImm(0)
+      .setMIFlag(MachineInstr::FrameSetup);
+
+  STI.getInstrInfo()->storeRegToStack(MBB, MBBI, Mips::K1, false,
+                                      MipsFI->getISRRegFI(0), PtrRC,
+                                      STI.getRegisterInfo(), 0);
+
+  // Fetch and Spill Status
+  MBB.addLiveIn(Mips::COP012);
+  BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::MFC0), Mips::K1)
+      .addReg(Mips::COP012)
+      .addImm(0)
+      .setMIFlag(MachineInstr::FrameSetup);
+
+  STI.getInstrInfo()->storeRegToStack(MBB, MBBI, Mips::K1, false,
+                                      MipsFI->getISRRegFI(1), PtrRC,
+                                      STI.getRegisterInfo(), 0);
+
+  // Build the configuration for disabling lower priority interrupts. Non EIC
+  // interrupts need to be masked off with zero, EIC from the Cause register.
+  unsigned InsPosition = 8;
+  unsigned InsSize = 0;
+  unsigned SrcReg = Mips::ZERO;
+
+  // If the interrupt we're tied to is the EIC, switch the source for the
+  // masking off interrupts to the cause register.
+  if (IntKind == "eic") {
+    SrcReg = Mips::K0;
+    InsPosition = 10;
+    InsSize = 6;
+  } else
+    InsSize = StringSwitch<unsigned>(IntKind)
+                  .Case("sw0", 1)
+                  .Case("sw1", 2)
+                  .Case("hw0", 3)
+                  .Case("hw1", 4)
+                  .Case("hw2", 5)
+                  .Case("hw3", 6)
+                  .Case("hw4", 7)
+                  .Case("hw5", 8)
+                  .Default(0);
+  assert(InsSize != 0 && "Unknown interrupt type!");
+
+  BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::INS), Mips::K1)
+      .addReg(SrcReg)
+      .addImm(InsPosition)
+      .addImm(InsSize)
+      .addReg(Mips::K1)
+      .setMIFlag(MachineInstr::FrameSetup);
+
+  // Mask off KSU, ERL, EXL
+  BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::INS), Mips::K1)
+      .addReg(Mips::ZERO)
+      .addImm(1)
+      .addImm(4)
+      .addReg(Mips::K1)
+      .setMIFlag(MachineInstr::FrameSetup);
+
+  // Disable the FPU as we are not spilling those register sets.
+  if (!STI.useSoftFloat())
+    BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::INS), Mips::K1)
+        .addReg(Mips::ZERO)
+        .addImm(29)
+        .addImm(1)
+        .addReg(Mips::K1)
+        .setMIFlag(MachineInstr::FrameSetup);
+
+  // Set the new status
+  BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::MTC0), Mips::COP012)
+      .addReg(Mips::K1)
+      .addImm(0)
+      .setMIFlag(MachineInstr::FrameSetup);
+}
+
 void MipsSEFrameLowering::emitEpilogue(MachineFunction &MF,
                                        MachineBasicBlock &MBB) const {
   MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
   MachineFrameInfo *MFI            = MF.getFrameInfo();
   MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
 
   const MipsSEInstrInfo &TII =
       *static_cast<const MipsSEInstrInfo *>(STI.getInstrInfo());
   const MipsRegisterInfo &RegInfo =
       *static_cast<const MipsRegisterInfo *>(STI.getRegisterInfo());
 
-  DebugLoc dl = MBBI->getDebugLoc();
+  DebugLoc DL = MBBI->getDebugLoc();
   MipsABIInfo ABI = STI.getABI();
   unsigned SP = ABI.GetStackPtr();
   unsigned FP = ABI.GetFramePtr();
   unsigned ZERO = ABI.GetNullPtr();
   unsigned MOVE = ABI.GetGPRMoveOp();
 
   // if framepointer enabled, restore the stack pointer.
   if (hasFP(MF)) {
     // Find the first instruction that restores a callee-saved register.
     MachineBasicBlock::iterator I = MBBI;
 
     for (unsigned i = 0; i < MFI->getCalleeSavedInfo().size(); ++i)
       --I;
 
     // Insert instruction "move $sp, $fp" at this location.
-    BuildMI(MBB, I, dl, TII.get(MOVE), SP).addReg(FP).addReg(ZERO);
+    BuildMI(MBB, I, DL, TII.get(MOVE), SP).addReg(FP).addReg(ZERO);
   }
 
   if (MipsFI->callsEhReturn()) {
     const TargetRegisterClass *RC =
         ABI.ArePtrs64bit() ? &Mips::GPR64RegClass : &Mips::GPR32RegClass;
 
     // 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, ABI.GetEhDataReg(J),
                                MipsFI->getEhDataRegFI(J), RC, &RegInfo);
     }
   }
 
+  if (MF.getFunction()->hasFnAttribute("interrupt"))
+    emitInterruptEpilogueStub(MF, MBB);
+
   // Get the number of bytes from FrameInfo
   uint64_t StackSize = MFI->getStackSize();
 
   if (!StackSize)
     return;
 
   // Adjust stack.
   TII.adjustStackPtr(SP, StackSize, MBB, MBBI);
 }
 
+void MipsSEFrameLowering::emitInterruptEpilogueStub(
+    MachineFunction &MF, MachineBasicBlock &MBB) const {
+
+  MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
+  MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
+  DebugLoc DL = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
+
+  // Perform ISR handling like GCC
+  const TargetRegisterClass *PtrRC = &Mips::GPR32RegClass;
+
+  // Disable Interrupts.
+  BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::DI), Mips::ZERO);
+  BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::EHB));
+
+  // Restore EPC
+  STI.getInstrInfo()->loadRegFromStackSlot(MBB, MBBI, Mips::K1,
+                                           MipsFI->getISRRegFI(0), PtrRC,
+                                           STI.getRegisterInfo());
+  BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::MTC0), Mips::COP014)
+      .addReg(Mips::K1)
+      .addImm(0);
+
+  // Restore Status
+  STI.getInstrInfo()->loadRegFromStackSlot(MBB, MBBI, Mips::K1,
+                                           MipsFI->getISRRegFI(1), PtrRC,
+                                           STI.getRegisterInfo());
+  BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::MTC0), Mips::COP012)
+      .addReg(Mips::K1)
+      .addImm(0);
+}
+
 bool MipsSEFrameLowering::
 spillCalleeSavedRegisters(MachineBasicBlock &MBB,
                           MachineBasicBlock::iterator MI,
                           const std::vector<CalleeSavedInfo> &CSI,
                           const TargetRegisterInfo *TRI) const {
   MachineFunction *MF = MBB.getParent();
   MachineBasicBlock *EntryBlock = &MF->front();
   const TargetInstrInfo &TII = *STI.getInstrInfo();
 
   for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
     // Add the callee-saved register as live-in. Do not add if the register is
     // RA and return address is taken, because it has already been added in
     // method MipsTargetLowering::LowerRETURNADDR.
     // It's killed at the spill, unless the register is RA and return address
     // is taken.
     unsigned Reg = CSI[i].getReg();
     bool IsRAAndRetAddrIsTaken = (Reg == Mips::RA || Reg == Mips::RA_64)
         && MF->getFrameInfo()->isReturnAddressTaken();
     if (!IsRAAndRetAddrIsTaken)
       EntryBlock->addLiveIn(Reg);
 
+    // ISRs require HI/LO to be spilled into kernel registers to be then
+    // spilled to the stack frame.
+    bool IsLOHI = (Reg == Mips::LO0 || Reg == Mips::LO0_64 ||
+                   Reg == Mips::HI0 || Reg == Mips::HI0_64);
+    const Function *Func = MBB.getParent()->getFunction();
+    if (IsLOHI && Func->hasFnAttribute("interrupt")) {
+      DebugLoc DL = MI->getDebugLoc();
+
+      unsigned Op = 0;
+      if (!STI.getABI().ArePtrs64bit()) {
+        Op = (Reg == Mips::HI0) ? Mips::MFHI : Mips::MFLO;
+        Reg = Mips::K0;
+      } else {
+        Op = (Reg == Mips::HI0) ? Mips::MFHI64 : Mips::MFLO64;
+        Reg = Mips::K0_64;
+      }
+      BuildMI(MBB, MI, DL, TII.get(Op), Mips::K0)
+          .setMIFlag(MachineInstr::FrameSetup);
+    }
+
     // Insert the spill to the stack frame.
     bool IsKill = !IsRAAndRetAddrIsTaken;
     const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
     TII.storeRegToStackSlot(*EntryBlock, MI, Reg, IsKill,
                             CSI[i].getFrameIdx(), RC, TRI);
   }
 
   return true;
void MipsSEFrameLowering::determineCalleeSaves(MachineFunction &MF,
   // Mark $s7 as used if function has dedicated base pointer.
   if (hasBP(MF))
     setAliasRegs(MF, SavedRegs, BP);
 
   // Create spill slots for eh data registers if function calls eh_return.
   if (MipsFI->callsEhReturn())
     MipsFI->createEhDataRegsFI();
 
+  // Create spill slots for Coprocessor 0 registers if function is an ISR.
+  if (MipsFI->isISR())
+    MipsFI->createISRRegFI();
+
   // Expand pseudo instructions which load, store or copy accumulators.
   // Add an emergency spill slot if a pseudo was expanded.
   if (ExpandPseudo(MF).expand()) {
     // The spill slot should be half the size of the accumulator. If target is
     // mips64, it should be 64-bit, otherwise it should be 32-bt.
     const TargetRegisterClass *RC = STI.hasMips64() ?
       &Mips::GPR64RegClass : &Mips::GPR32RegClass;
     int FI = MF.getFrameInfo()->CreateStackObject(RC->getSize(),

llvm/trunk/lib/Target/Mips/MipsSEISelLowering.cpp

 }
 
 bool MipsSETargetLowering::isEligibleForTailCallOptimization(
     const CCState &CCInfo, unsigned NextStackOffset,
     const MipsFunctionInfo &FI) const {
   if (!EnableMipsTailCalls)
     return false;
 
+  // Exception has to be cleared with eret.
+  if (FI.isISR())
+    return false;
+
   // Return false if either the callee or caller has a byval argument.
   if (CCInfo.getInRegsParamsCount() > 0 || FI.hasByvalArg())
     return false;
 
   // Return true if the callee's argument area is no larger than the
   // caller's.
   return NextStackOffset <= FI.getIncomingArgSize();
 }

llvm/trunk/lib/Target/Mips/MipsSEInstrInfo.h

unsigned loadImmediate(int64_t Imm, MachineBasicBlock &MBB,
                          MachineBasicBlock::iterator II, DebugLoc DL,
                          unsigned *NewImm) const;
 
 private:
   unsigned getAnalyzableBrOpc(unsigned Opc) const override;
 
   void expandRetRA(MachineBasicBlock &MBB, MachineBasicBlock::iterator I) const;
 
+  void expandERet(MachineBasicBlock &MBB, MachineBasicBlock::iterator I) const;
+
   std::pair<bool, bool> compareOpndSize(unsigned Opc,
                                         const MachineFunction &MF) const;
 
   void expandPseudoMFHiLo(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
                           unsigned NewOpc) const;
 
   void expandPseudoMTLoHi(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
                           unsigned LoOpc, unsigned HiOpc,

llvm/trunk/lib/Target/Mips/MipsSEInstrInfo.cpp

storeRegToStack(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
   else if (RC->hasType(MVT::v16i8))
     Opc = Mips::ST_B;
   else if (RC->hasType(MVT::v8i16) || RC->hasType(MVT::v8f16))
     Opc = Mips::ST_H;
   else if (RC->hasType(MVT::v4i32) || RC->hasType(MVT::v4f32))
     Opc = Mips::ST_W;
   else if (RC->hasType(MVT::v2i64) || RC->hasType(MVT::v2f64))
     Opc = Mips::ST_D;
+  else if (Mips::LO32RegClass.hasSubClassEq(RC))
+    Opc = Mips::SW;
+  else if (Mips::LO64RegClass.hasSubClassEq(RC))
+    Opc = Mips::SD;
+  else if (Mips::HI32RegClass.hasSubClassEq(RC))
+    Opc = Mips::SW;
+  else if (Mips::HI64RegClass.hasSubClassEq(RC))
+    Opc = Mips::SD;
+
+  // Hi, Lo are normally caller save but they are callee save
+  // for interrupt handling.
+  const Function *Func = MBB.getParent()->getFunction();
+  if (Func->hasFnAttribute("interrupt")) {
+    if (Mips::HI32RegClass.hasSubClassEq(RC)) {
+      BuildMI(MBB, I, DL, get(Mips::MFHI), Mips::K0);
+      SrcReg = Mips::K0;
+    } else if (Mips::HI64RegClass.hasSubClassEq(RC)) {
+      BuildMI(MBB, I, DL, get(Mips::MFHI64), Mips::K0_64);
+      SrcReg = Mips::K0_64;
+    } else if (Mips::LO32RegClass.hasSubClassEq(RC)) {
+      BuildMI(MBB, I, DL, get(Mips::MFLO), Mips::K0);
+      SrcReg = Mips::K0;
+    } else if (Mips::LO64RegClass.hasSubClassEq(RC)) {
+      BuildMI(MBB, I, DL, get(Mips::MFLO64), Mips::K0_64);
+      SrcReg = Mips::K0_64;
+    }
+  }
 
   assert(Opc && "Register class not handled!");
   BuildMI(MBB, I, DL, get(Opc)).addReg(SrcReg, getKillRegState(isKill))
     .addFrameIndex(FI).addImm(Offset).addMemOperand(MMO);
 }
 
 void MipsSEInstrInfo::
 loadRegFromStack(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
                  unsigned DestReg, int FI, const TargetRegisterClass *RC,
                  const TargetRegisterInfo *TRI, int64_t Offset) const {
   DebugLoc DL;
   if (I != MBB.end()) DL = I->getDebugLoc();
   MachineMemOperand *MMO = GetMemOperand(MBB, FI, MachineMemOperand::MOLoad);
   unsigned Opc = 0;
 
+  const Function *Func = MBB.getParent()->getFunction();
+  bool ReqIndirectLoad = Func->hasFnAttribute("interrupt") &&
+                         (DestReg == Mips::LO0 || DestReg == Mips::LO0_64 ||
+                          DestReg == Mips::HI0 || DestReg == Mips::HI0_64);
+
   if (Mips::GPR32RegClass.hasSubClassEq(RC))
     Opc = Mips::LW;
   else if (Mips::GPR64RegClass.hasSubClassEq(RC))
     Opc = Mips::LD;
   else if (Mips::ACC64RegClass.hasSubClassEq(RC))
     Opc = Mips::LOAD_ACC64;
   else if (Mips::ACC64DSPRegClass.hasSubClassEq(RC))
     Opc = Mips::LOAD_ACC64DSP;
loadRegFromStack(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
   else if (RC->hasType(MVT::v16i8))
     Opc = Mips::LD_B;
   else if (RC->hasType(MVT::v8i16) || RC->hasType(MVT::v8f16))
     Opc = Mips::LD_H;
   else if (RC->hasType(MVT::v4i32) || RC->hasType(MVT::v4f32))
     Opc = Mips::LD_W;
   else if (RC->hasType(MVT::v2i64) || RC->hasType(MVT::v2f64))
     Opc = Mips::LD_D;
+  else if (Mips::HI32RegClass.hasSubClassEq(RC))
+    Opc = Mips::LW;
+  else if (Mips::HI64RegClass.hasSubClassEq(RC))
+    Opc = Mips::LD;
+  else if (Mips::LO32RegClass.hasSubClassEq(RC))
+    Opc = Mips::LW;
+  else if (Mips::LO64RegClass.hasSubClassEq(RC))
+    Opc = Mips::LD;
 
   assert(Opc && "Register class not handled!");
-  BuildMI(MBB, I, DL, get(Opc), DestReg).addFrameIndex(FI).addImm(Offset)
+
+  if (!ReqIndirectLoad)
+    BuildMI(MBB, I, DL, get(Opc), DestReg)
+        .addFrameIndex(FI)
+        .addImm(Offset)
         .addMemOperand(MMO);
+  else {
+    // Load HI/LO through K0. Notably the DestReg is encoded into the
+    // instruction itself.
+    unsigned Reg = Mips::K0;
+    unsigned LdOp = Mips::MTLO;
+    if (DestReg == Mips::HI0)
+      LdOp = Mips::MTHI;
+
+    if (Subtarget.getABI().ArePtrs64bit()) {
+      Reg = Mips::K0_64;
+      if (DestReg == Mips::HI0_64)
+        LdOp = Mips::MTHI64;
+      else
+        LdOp = Mips::MTLO64;
+    }
+
+    BuildMI(MBB, I, DL, get(Opc), Reg)
+        .addFrameIndex(FI)
+        .addImm(Offset)
+        .addMemOperand(MMO);
+    BuildMI(MBB, I, DL, get(LdOp)).addReg(Reg);
+  }
 }
 
 bool MipsSEInstrInfo::expandPostRAPseudo(MachineBasicBlock::iterator MI) const {
   MachineBasicBlock &MBB = *MI->getParent();
   bool isMicroMips = Subtarget.inMicroMipsMode();
   unsigned Opc;
 
   switch(MI->getDesc().getOpcode()) {
   default:
     return false;
   case Mips::RetRA:
     expandRetRA(MBB, MI);
     break;
+  case Mips::ERet:
+    expandERet(MBB, MI);
+    break;
   case Mips::PseudoMFHI:
     Opc = isMicroMips ? Mips::MFHI16_MM : Mips::MFHI;
     expandPseudoMFHiLo(MBB, MI, Opc);
     break;
   case Mips::PseudoMFLO:
     Opc = isMicroMips ? Mips::MFLO16_MM : Mips::MFLO;
     expandPseudoMFHiLo(MBB, MI, Opc);
     break;
void MipsSEInstrInfo::expandRetRA(MachineBasicBlock &MBB,
                                   MachineBasicBlock::iterator I) const {
   if (Subtarget.isGP64bit())
     BuildMI(MBB, I, I->getDebugLoc(), get(Mips::PseudoReturn64))
         .addReg(Mips::RA_64);
   else
     BuildMI(MBB, I, I->getDebugLoc(), get(Mips::PseudoReturn)).addReg(Mips::RA);
 }
 
+void MipsSEInstrInfo::expandERet(MachineBasicBlock &MBB,
+                                 MachineBasicBlock::iterator I) const {
+  BuildMI(MBB, I, I->getDebugLoc(), get(Mips::ERET));
+}
+
 std::pair<bool, bool>
 MipsSEInstrInfo::compareOpndSize(unsigned Opc,
                                  const MachineFunction &MF) const {
   const MCInstrDesc &Desc = get(Opc);
   assert(Desc.NumOperands == 2 && "Unary instruction expected.");
   const MipsRegisterInfo *RI = &getRegisterInfo();
   unsigned DstRegSize = getRegClass(Desc, 0, RI, MF)->getSize();
   unsigned SrcRegSize = getRegClass(Desc, 1, RI, MF)->getSize();

llvm/trunk/lib/Target/Mips/MipsSERegisterInfo.cpp

void MipsSERegisterInfo::eliminateFI(MachineBasicBlock::iterator II,
   int MaxCSFI = -1;
 
   if (CSI.size()) {
     MinCSFI = CSI[0].getFrameIdx();
     MaxCSFI = CSI[CSI.size() - 1].getFrameIdx();
   }
 
   bool EhDataRegFI = MipsFI->isEhDataRegFI(FrameIndex);
-
+  bool IsISRRegFI = MipsFI->isISRRegFI(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.
+  //  5. Locations for ISR saved Coprocessor 0 registers 12 & 14.
   // Everything else is referenced relative to whatever register
   // getFrameRegister() returns.
   unsigned FrameReg;
 
-  if ((FrameIndex >= MinCSFI && FrameIndex <= MaxCSFI) || EhDataRegFI)
+  if ((FrameIndex >= MinCSFI && FrameIndex <= MaxCSFI) || EhDataRegFI ||
+      IsISRRegFI)
     FrameReg = ABI.GetStackPtr();
   else if (RegInfo->needsStackRealignment(MF)) {
     if (MFI->hasVarSizedObjects() && !MFI->isFixedObjectIndex(FrameIndex))
       FrameReg = ABI.GetBasePtr();
     else if (MFI->isFixedObjectIndex(FrameIndex))
       FrameReg = getFrameRegister(MF);
     else
       FrameReg = ABI.GetStackPtr();

llvm/trunk/test/CodeGen/Mips/interrupt-attr-64-fail.ll

+; RUN: llc -mcpu=mips64r6 -march=mipsel -relocation-model=static -o - %s | FileCheck %s
+; XFAIL: *
+
+define void @isr_sw0() #0 {
+  call void bitcast (void (...)* @write to void ()*)()
+}
+
+declare void @write(...)
+
+attributes #0 = { "interrupt"="sw0" }
+

llvm/trunk/test/CodeGen/Mips/interrupt-attr-args-fail.ll

+; RUN: llc -mcpu=mips32r2 -march=mipsel -relocation-model=static -o - %s | FileCheck %s
+; XFAIL: *
+
+define void @isr_sw0(i8 signext %n) #0 {
+  call void bitcast (void (...)* @write to void ()*)()
+}
+
+declare void @write(...)
+
+attributes #0 = { "interrupt"="sw0" }
+

llvm/trunk/test/CodeGen/Mips/interrupt-attr-fail.ll

+; RUN: llc -mcpu=mips32 -march=mipsel -relocation-model=static -o - %s | FileCheck %s
+; XFAIL: *
+
+define void @isr_sw0() #0 {
+  call void bitcast (void (...)* @write to void ()*)()
+}
+
+declare void @write(...)
+
+attributes #0 = { "interrupt"="sw0" }
+

llvm/trunk/test/CodeGen/Mips/interrupt-attr.ll

+; RUN: llc -mcpu=mips32r2 -march=mipsel -relocation-model=static -o - %s | FileCheck %s
+
+define void @isr_sw0() #0 {
+; CHECK-LABEL: isr_sw0:
+; CHECK: mfc0   $27, $14, 0
+; CHECK: sw     $27, [[R1:[0-9]+]]($sp)
+; CHECK: mfc0   $27, $12, 0
+; CHECK: sw     $27, [[R2:[0-9]+]]($sp)
+; CHECK: ins    $27, $zero, 8, 1
+; CHECK: ins    $27, $zero, 1, 4
+; CHECK: ins    $27, $zero, 29, 1
+; CHECK: mtc0   $27, $12, 0
+  ; Must save all registers
+; CHECK: sw      $7, {{[0-9]+}}($sp)
+; CHECK: sw      $6, {{[0-9]+}}($sp)
+; CHECK: sw      $5, {{[0-9]+}}($sp)
+; CHECK: sw      $4, {{[0-9]+}}($sp)
+; CHECK: sw      $3, {{[0-9]+}}($sp)
+; CHECK: sw      $2, {{[0-9]+}}($sp)
+; CHECK: sw      $25, {{[0-9]+}}($sp)
+; CHECK: sw      $24, {{[0-9]+}}($sp)
+; CHECK: sw      $15, {{[0-9]+}}($sp)
+; CHECK: sw      $14, {{[0-9]+}}($sp)
+; CHECK: sw      $13, {{[0-9]+}}($sp)
+; CHECK: sw      $12, {{[0-9]+}}($sp)
+; CHECK: sw      $11, {{[0-9]+}}($sp)
+; CHECK: sw      $10, {{[0-9]+}}($sp)
+; CHECK: sw      $9, {{[0-9]+}}($sp)
+; CHECK: sw      $8, {{[0-9]+}}($sp)
+; CHECK: sw      $ra, [[R5:[0-9]+]]($sp)
+; CHECK: sw      $gp, {{[0-9]+}}($sp)
+; CHECK: sw      $1, {{[0-9]+}}($sp)
+; CHECK: mflo    $26
+; CHECK: sw      $26, [[R3:[0-9]+]]($sp)
+; CHECK: mfhi    $26
+; CHECK: sw      $26, [[R4:[0-9]+]]($sp)
+  call void bitcast (void (...)* @write to void ()*)()
+; CHECK: lw      $26, [[R4:[0-9]+]]($sp)
+; CHECK: mthi    $26
+; CHECK: lw      $26, [[R3:[0-9]+]]($sp)
+; CHECK: mtlo    $26
+; CHECK: lw      $1, {{[0-9]+}}($sp)
+; CHECK: lw      $gp, {{[0-9]+}}($sp)
+; CHECK: lw      $ra, [[R5:[0-9]+]]($sp)
+; CHECK: lw      $8, {{[0-9]+}}($sp)
+; CHECK: lw      $9, {{[0-9]+}}($sp)
+; CHECK: lw      $10, {{[0-9]+}}($sp)
+; CHECK: lw      $11, {{[0-9]+}}($sp)
+; CHECK: lw      $12, {{[0-9]+}}($sp)
+; CHECK: lw      $13, {{[0-9]+}}($sp)
+; CHECK: lw      $14, {{[0-9]+}}($sp)
+; CHECK: lw      $15, {{[0-9]+}}($sp)
+; CHECK: lw      $24, {{[0-9]+}}($sp)
+; CHECK: lw      $25, {{[0-9]+}}($sp)
+; CHECK: lw      $2, {{[0-9]+}}($sp)
+; CHECK: lw      $3, {{[0-9]+}}($sp)
+; CHECK: lw      $4, {{[0-9]+}}($sp)
+; CHECK: lw      $5, {{[0-9]+}}($sp)
+; CHECK: lw      $6, {{[0-9]+}}($sp)
+; CHECK: lw      $7, {{[0-9]+}}($sp)
+; CHECK: di
+; CHECK: ehb
+; CHECK: lw      $27, [[R2:[0-9]+]]($sp)
+; CHECK: mtc0    $27, $14, 0
+; CHECK: lw      $27, [[R1:[0-9]+]]($sp)
+; CHECK: mtc0    $27, $12, 0
+; CHECK: eret
+  ret void
+}
+
+declare void @write(...)
+
+define void @isr_sw1() #2 {
+; CHECK-LABEL: isr_sw1:
+; CHECK: mfc0   $27, $14, 0
+; CHECK: sw     $27, {{[0-9]+}}($sp)
+; CHECK: mfc0   $27, $12, 0
+; CHECK: sw     $27, {{[0-9]+}}($sp)
+; CHECK: ins    $27, $zero, 8, 2
+; CHECK: ins    $27, $zero, 1, 4
+; CHECK: ins    $27, $zero, 29, 1
+; CHECK: mtc0   $27, $12, 0
+  ret void
+; CHECK: di
+; CHECK: ehb
+; CHECK: lw      $27, {{[0-9]+}}($sp)
+; CHECK: mtc0    $27, $14, 0
+; CHECK: lw      $27, {{[0-9]+}}($sp)
+; CHECK: mtc0    $27, $12, 0
+; CHECK: eret
+ }
+
+define void @isr_hw0() #3 {
+; CHECK-LABEL: isr_hw0:
+; CHECK: mfc0   $27, $14, 0
+; CHECK: sw     $27, {{[0-9]+}}($sp)
+; CHECK: mfc0   $27, $12, 0
+; CHECK: sw     $27, {{[0-9]+}}($sp)
+; CHECK: ins    $27, $zero, 8, 3
+; CHECK: ins    $27, $zero, 1, 4
+; CHECK: ins    $27, $zero, 29, 1
+; CHECK: mtc0   $27, $12, 0
+  ret void
+; CHECK: di
+; CHECK: ehb
+; CHECK: lw      $27, {{[0-9]+}}($sp)
+; CHECK: mtc0    $27, $14, 0
+; CHECK: lw      $27, {{[0-9]+}}($sp)
+; CHECK: mtc0    $27, $12, 0
+; CHECK: eret
+ }
+
+define void @isr_hw1() #4 {
+; CHECK-LABEL: isr_hw1:
+; CHECK: mfc0   $27, $14, 0
+; CHECK: sw     $27, {{[0-9]+}}($sp)
+; CHECK: mfc0   $27, $12, 0
+; CHECK: sw     $27, {{[0-9]+}}($sp)
+; CHECK: ins    $27, $zero, 8, 4
+; CHECK: ins    $27, $zero, 1, 4
+; CHECK: ins    $27, $zero, 29, 1
+; CHECK: mtc0   $27, $12, 0
+  ret void
+; CHECK: di
+; CHECK: ehb
+; CHECK: lw      $27, {{[0-9]+}}($sp)
+; CHECK: mtc0    $27, $14, 0
+; CHECK: lw      $27, {{[0-9]+}}($sp)
+; CHECK: mtc0    $27, $12, 0
+; CHECK: eret
+ }
+
+
+define void @isr_hw2() #5 {
+; CHECK-LABEL: isr_hw2:
+; CHECK: mfc0   $27, $14, 0
+; CHECK: sw     $27, {{[0-9]+}}($sp)
+; CHECK: mfc0   $27, $12, 0
+; CHECK: sw     $27, {{[0-9]+}}($sp)
+; CHECK: ins    $27, $zero, 8, 5
+; CHECK: ins    $27, $zero, 1, 4
+; CHECK: ins    $27, $zero, 29, 1
+; CHECK: mtc0   $27, $12, 0
+  ret void
+; CHECK: di
+; CHECK: ehb
+; CHECK: lw      $27, {{[0-9]+}}($sp)
+; CHECK: mtc0    $27, $14, 0
+; CHECK: lw      $27, {{[0-9]+}}($sp)
+; CHECK: mtc0    $27, $12, 0
+; CHECK: eret
+ }
+
+define void @isr_hw3() #6 {
+; CHECK-LABEL: isr_hw3:
+; CHECK: mfc0   $27, $14, 0
+; CHECK: sw     $27, {{[0-9]+}}($sp)
+; CHECK: mfc0   $27, $12, 0
+; CHECK: sw     $27, {{[0-9]+}}($sp)
+; CHECK: ins    $27, $zero, 8, 6
+; CHECK: ins    $27, $zero, 1, 4
+; CHECK: ins    $27, $zero, 29, 1
+; CHECK: mtc0   $27, $12, 0
+  ret void
+; CHECK: di
+; CHECK: ehb
+; CHECK: lw      $27, {{[0-9]+}}($sp)
+; CHECK: mtc0    $27, $14, 0
+; CHECK: lw      $27, {{[0-9]+}}($sp)
+; CHECK: mtc0    $27, $12, 0
+; CHECK: eret
+ }
+
+define void @isr_hw4() #7 {
+; CHECK-LABEL: isr_hw4:
+; CHECK: mfc0   $27, $14, 0
+; CHECK: sw     $27, {{[0-9]+}}($sp)
+; CHECK: mfc0   $27, $12, 0
+; CHECK: sw     $27, {{[0-9]+}}($sp)
+; CHECK: ins    $27, $zero, 8, 7
+; CHECK: ins    $27, $zero, 1, 4
+; CHECK: ins    $27, $zero, 29, 1
+; CHECK: mtc0   $27, $12, 0
+  ret void
+; CHECK: di
+; CHECK: ehb
+; CHECK: lw      $27, {{[0-9]+}}($sp)
+; CHECK: mtc0    $27, $14, 0
+; CHECK: lw      $27, {{[0-9]+}}($sp)
+; CHECK: mtc0    $27, $12, 0
+; CHECK: eret
+ }
+
+define void @isr_hw5() #8 {
+; CHECK-LABEL: isr_hw5:
+; CHECK: mfc0   $27, $14, 0
+; CHECK: sw     $27, {{[0-9]+}}($sp)
+; CHECK: mfc0   $27, $12, 0
+; CHECK: sw     $27, {{[0-9]+}}($sp)
+; CHECK: ins    $27, $zero, 8, 8
+; CHECK: ins    $27, $zero, 1, 4
+; CHECK: ins    $27, $zero, 29, 1
+; CHECK: mtc0   $27, $12, 0
+  ret void
+; CHECK: di
+; CHECK: ehb
+; CHECK: lw      $27, {{[0-9]+}}($sp)
+; CHECK: mtc0    $27, $14, 0
+; CHECK: lw      $27, {{[0-9]+}}($sp)
+; CHECK: mtc0    $27, $12, 0
+; CHECK: eret
+ }
+
+define void @isr_eic() #9 {
+; CHECK-LABEL: isr_eic:
+; CHECK: mfc0   $26, $13, 0
+; CHECK: ext    $26, $26, 10, 6
+; CHECK: mfc0   $27, $14, 0
+; CHECK: sw     $27, {{[0-9]+}}($sp)
+; CHECK: mfc0   $27, $12, 0
+; CHECK: sw     $27, {{[0-9]+}}($sp)
+; CHECK: ins    $27, $26, 10, 6
+; CHECK: ins    $27, $zero, 1, 4
+; CHECK: ins    $27, $zero, 29, 1
+; CHECK: mtc0   $27, $12, 0
+  ret void
+; CHECK: di
+; CHECK: ehb
+; CHECK: lw      $27, {{[0-9]+}}($sp)
+; CHECK: mtc0    $27, $14, 0
+; CHECK: lw      $27, {{[0-9]+}}($sp)
+; CHECK: mtc0    $27, $12, 0
+; CHECK: eret
+ }
+
+attributes #0 = { "interrupt"="sw0" }
+attributes #2 = { "interrupt"="sw1" }
+attributes #3 = { "interrupt"="hw0" }
+attributes #4 = { "interrupt"="hw1" }
+attributes #5 = { "interrupt"="hw2" }
+attributes #6 = { "interrupt"="hw3" }
+attributes #7 = { "interrupt"="hw4" }
+attributes #8 = { "interrupt"="hw5" }
+attributes #9 = { "interrupt"="eic" }