[mips][microMIPS] Implement SWM16 and LWM16 instructions

[zoran.jovanovic]

Rebased.
Error handling changed.
Offset shift fixed.

[sstankovic]

lib/Target/Mips/AsmParser/MipsAsmParser.cpp

792

This method is never called. I think the problem is that you use parseRegisterList for parsing RegList16 operands. At the end of parseRegisterList, operand of k_RegList is created, which means that isRegList() will be called instead of isRegList16().

lib/Target/Mips/MicroMipsInstrInfo.td

215

You probably need RegListAsmOperand here.

[zoran.jovanovic]

Patch rebased and some unnecessary code removed.

[sstankovic]

For the following illegal instructions the error is not reported:

lwm16 $16, 8($sp)
lwm16 $16, $17, 8($sp)
lwm16 $16-$20, 8($sp)

Please include these instructions in the tests, to make sure the error is reported.

lib/Target/Mips/Disassembler/MipsDisassembler.cpp

348

You can put "unsigned Insn" on the previous line - it fits in 80 columns.

1422

Same here.

[zoran.jovanovic]

PredicateMethod added to check whether reglistoperand16 is valid.

[sstankovic]

LGTM, with two changes.

lib/Target/Mips/MicroMipsInstrInfo.td

374

This line is unaligned.

381

Same here.

Closed by commit rL222901 (authored by zjovanovic).

lib/Target/Mips/AsmParser/MipsAsmParser.cpp

public:
   bool isReg() const override {
     // As a special case until we sort out the definition of div/divu, pretend
     // that $0/$zero are k_PhysRegister so that MCK_ZERO works correctly.
     if (isGPRAsmReg() && RegIdx.Index == 0)
       return true;
 
     return Kind == k_PhysRegister;
   }
   bool isRegIdx() const { return Kind == k_RegisterIndex; }
   bool isImm() const override { return Kind == k_Immediate; }
   bool isConstantImm() const {
     return isImm() && dyn_cast<MCConstantExpr>(getImm());
   }
   bool isToken() const override {
     // Note: It's not possible to pretend that other operand kinds are tokens.
     // The matcher emitter checks tokens first.
     return Kind == k_Token;
   }
   bool isMem() const override { return Kind == k_Memory; }
   bool isConstantMemOff() const {
     return isMem() && dyn_cast<MCConstantExpr>(getMemOff());
   }
   template <unsigned Bits> bool isMemWithSimmOffset() const {
     return isMem() && isConstantMemOff() && isInt<Bits>(getConstantMemOff());
   }
   bool isMemWithGRPMM16Base() const {
     return isMem() && getMemBase()->isMM16AsmReg();
   }
+  template <unsigned Bits> bool isMemWithUimmOffsetSP() const {
+    return isMem() && isConstantMemOff() && isUInt<Bits>(getConstantMemOff())
+      && getMemBase()->isRegIdx() && (getMemBase()->getGPR32Reg() == Mips::SP);
+  }
+  bool isRegList16() const {
+    if (!isRegList())
+      return false;
+
+    int Size = RegList.List->size();
+    if (Size < 2 || Size > 5 || *RegList.List->begin() != Mips::S0 ||
+        RegList.List->back() != Mips::RA)
+      return false;
+
+    int PrevReg = *RegList.List->begin();
+    for (int i = 1; i < Size - 1; i++) {
+      int Reg = (*(RegList.List))[i];
+      if ( Reg != PrevReg + 1)
+        return false;
+      PrevReg = Reg;
+    }
+
+    return true;
+  }
   bool isInvNum() const { return Kind == k_Immediate; }
   bool isLSAImm() const {
     if (!isConstantImm())
       return false;
     int64_t Val = getConstantImm();
     return 1 <= Val && Val <= 4;
   }
   bool isRegList() const { return Kind == k_RegList; }

lib/Target/Mips/Disassembler/MipsDisassembler.cpp

 static DecodeStatus
 DecodeBgtzGroupBranch(MCInst &MI, InsnType insn, uint64_t Address,
                       const void *Decoder);
 
 template <typename InsnType>
 static DecodeStatus
 DecodeBlezGroupBranch(MCInst &MI, InsnType insn, uint64_t Address,
                        const void *Decoder);
 
 static DecodeStatus DecodeRegListOperand(MCInst &Inst, unsigned Insn,
                                          uint64_t Address,
                                          const void *Decoder);
 
+static DecodeStatus DecodeRegListOperand16(MCInst &Inst, unsigned Insn,
+                                           uint64_t Address,
+                                           const void *Decoder);
+
 namespace llvm {
 extern Target TheMipselTarget, TheMipsTarget, TheMips64Target,
               TheMips64elTarget;
 }
 
 static MCDisassembler *createMipsDisassembler(
                        const Target &T,
                        const MCSubtargetInfo &STI,
static DecodeStatus DecodeLSAImm(MCInst &Inst,
                                  uint64_t Address,
                                  const void *Decoder) {
   // We add one to the immediate field as it was encoded as 'imm - 1'.
   Inst.addOperand(MCOperand::CreateImm(Insn + 1));
   return MCDisassembler::Success;
 }
 
 static DecodeStatus DecodeInsSize(MCInst &Inst,
                                   unsigned Insn,
                                   uint64_t Address,
                                   const void *Decoder) {
   // First we need to grab the pos(lsb) from MCInst.
   int Pos = Inst.getOperand(2).getImm();
   int Size = (int) Insn - Pos + 1;
   Inst.addOperand(MCOperand::CreateImm(SignExtend32<16>(Size)));
   return MCDisassembler::Success;
 }
static DecodeStatus DecodeRegListOperand(MCInst &Inst,
   for (unsigned i = 0; i < RegNum; i++)
     Inst.addOperand(MCOperand::CreateReg(Regs[i]));
 
   if (RegLst & 0x10)
     Inst.addOperand(MCOperand::CreateReg(Mips::RA));
 
   return MCDisassembler::Success;
 }
+
+static DecodeStatus DecodeRegListOperand16(MCInst &Inst, unsigned Insn,
+                                           uint64_t Address,
+                                           const void *Decoder) {
+  unsigned Regs[] = {Mips::S0, Mips::S1, Mips::S2, Mips::S3};
+  unsigned RegNum;
+
+  unsigned RegLst = fieldFromInstruction(Insn, 4, 2);
+  // Empty register lists are not allowed.
+  if (RegLst == 0)
+    return MCDisassembler::Fail;
+
+  RegNum = RegLst & 0x3;
+  for (unsigned i = 0; i < RegNum - 1; i++)
+    Inst.addOperand(MCOperand::CreateReg(Regs[i]));
+
+  Inst.addOperand(MCOperand::CreateReg(Mips::RA));
+
+  return MCDisassembler::Success;
+}

lib/Target/Mips/InstPrinter/MipsInstPrinter.cpp

printMemOperand(const MCInst *MI, int opNum, raw_ostream &O) {
 
   // opNum can be invalid if instruction had reglist as operand.
   // MemOperand is always last operand of instruction (base + offset).
   switch (MI->getOpcode()) {
   default:
     break;
   case Mips::SWM32_MM:
   case Mips::LWM32_MM:
+  case Mips::SWM16_MM:
+  case Mips::LWM16_MM:
     opNum = MI->getNumOperands() - 2;
     break;
   }
 
   printOperand(MI, opNum+1, O);
   O << "(";
   printOperand(MI, opNum, O);
   O << ")";

lib/Target/Mips/MCTargetDesc/MipsMCCodeEmitter.h

unsigned getMemEncodingMMImm4Lsl1(const MCInst &MI, unsigned OpNo,
                                     SmallVectorImpl<MCFixup> &Fixups,
                                     const MCSubtargetInfo &STI) const;
   unsigned getMemEncodingMMImm4Lsl2(const MCInst &MI, unsigned OpNo,
                                     SmallVectorImpl<MCFixup> &Fixups,
                                     const MCSubtargetInfo &STI) const;
   unsigned getMemEncodingMMImm12(const MCInst &MI, unsigned OpNo,
                                  SmallVectorImpl<MCFixup> &Fixups,
                                  const MCSubtargetInfo &STI) const;
+  unsigned getMemEncodingMMImm4sp(const MCInst &MI, unsigned OpNo,
+                                  SmallVectorImpl<MCFixup> &Fixups,
+                                  const MCSubtargetInfo &STI) const;
   unsigned getSizeExtEncoding(const MCInst &MI, unsigned OpNo,
                               SmallVectorImpl<MCFixup> &Fixups,
                               const MCSubtargetInfo &STI) const;
   unsigned getSizeInsEncoding(const MCInst &MI, unsigned OpNo,
                               SmallVectorImpl<MCFixup> &Fixups,
                               const MCSubtargetInfo &STI) const;
 
   // getLSAImmEncoding - Return binary encoding of LSA immediate.
unsigned getUImm4AndValue(const MCInst &MI, unsigned OpNo,
                             const MCSubtargetInfo &STI) const;
 
   unsigned getExprOpValue(const MCExpr *Expr, SmallVectorImpl<MCFixup> &Fixups,
                           const MCSubtargetInfo &STI) const;
 
   unsigned getRegisterListOpValue(const MCInst &MI, unsigned OpNo,
                                   SmallVectorImpl<MCFixup> &Fixups,
                                   const MCSubtargetInfo &STI) const;
+
+  unsigned getRegisterListOpValue16(const MCInst &MI, unsigned OpNo,
+                                    SmallVectorImpl<MCFixup> &Fixups,
+                                    const MCSubtargetInfo &STI) const;
 }; // class MipsMCCodeEmitter
 } // namespace llvm.
 
 #endif

lib/Target/Mips/MCTargetDesc/MipsMCCodeEmitter.cpp

getMemEncodingMMImm12(const MCInst &MI, unsigned OpNo,
   // Base register is encoded in bits 20-16, offset is encoded in bits 11-0.
   assert(MI.getOperand(OpNo).isReg());
   unsigned RegBits = getMachineOpValue(MI, MI.getOperand(OpNo), Fixups, STI) << 16;
   unsigned OffBits = getMachineOpValue(MI, MI.getOperand(OpNo+1), Fixups, STI);
 
   return (OffBits & 0x0FFF) | RegBits;
 }
 
+unsigned MipsMCCodeEmitter::
+getMemEncodingMMImm4sp(const MCInst &MI, unsigned OpNo,
+                       SmallVectorImpl<MCFixup> &Fixups,
+                       const MCSubtargetInfo &STI) const {
+  // opNum can be invalid if instruction had reglist as operand
+  // MemOperand is always last operand of instruction (base + offset)
+  switch (MI.getOpcode()) {
+  default:
+    break;
+  case Mips::SWM16_MM:
+  case Mips::LWM16_MM:
+    OpNo = MI.getNumOperands() - 2;
+    break;
+  }
+
+  // Offset is encoded in bits 4-0.
+  assert(MI.getOperand(OpNo).isReg());
+  // Base register is always SP - thus it is not encoded.
+  assert(MI.getOperand(OpNo+1).isImm());
+  unsigned OffBits = getMachineOpValue(MI, MI.getOperand(OpNo+1), Fixups, STI);
+
+  return ((OffBits >> 2) & 0x0F);
+}
+
 unsigned
 MipsMCCodeEmitter::getSizeExtEncoding(const MCInst &MI, unsigned OpNo,
                                       SmallVectorImpl<MCFixup> &Fixups,
                                       const MCSubtargetInfo &STI) const {
   assert(MI.getOperand(OpNo).isImm());
   unsigned SizeEncoding = getMachineOpValue(MI, MI.getOperand(OpNo), Fixups, STI);
   return SizeEncoding - 1;
 }
for (unsigned I = OpNo, E = MI.getNumOperands() - 2; I < E; ++I) {
     if (RegNo != 31)
       res++;
     else
       res |= 0x10;
   }
   return res;
 }
 
+unsigned
+MipsMCCodeEmitter::getRegisterListOpValue16(const MCInst &MI, unsigned OpNo,
+                                            SmallVectorImpl<MCFixup> &Fixups,
+                                            const MCSubtargetInfo &STI) const {
+  return (MI.getNumOperands() - 4);
+}
+
 #include "MipsGenMCCodeEmitter.inc"

lib/Target/Mips/MicroMipsInstrFormats.td

class LWM_FM_MM<bits<4> funct> : MMArch {
   bits<32> Inst;
 
   let Inst{31-26} = 0x8;
   let Inst{25-21} = rt;
   let Inst{20-16} = addr{20-16};
   let Inst{15-12} = funct;
   let Inst{11-0}  = addr{11-0};
 }
+
+class LWM_FM_MM16<bits<4> funct> : MMArch {
+  bits<2> rt;
+  bits<4> addr;
+
+  bits<16> Inst;
+
+  let Inst{15-10} = 0x11;
+  let Inst{9-6}   = funct;
+  let Inst{5-4}   = rt;
+  let Inst{3-0}   = addr;
+}

lib/Target/Mips/MicroMipsInstrInfo.td

 def mem_mm_12 : Operand<i32> {
   let PrintMethod = "printMemOperand";
   let MIOperandInfo = (ops GPR32, simm12);
   let EncoderMethod = "getMemEncodingMMImm12";
   let ParserMatchClass = MipsMemAsmOperand;
   let OperandType = "OPERAND_MEMORY";
 }
 
+def MipsMemUimm4AsmOperand : AsmOperandClass {
+  let Name = "MemOffsetUimm4";
+  let SuperClasses = [MipsMemAsmOperand];
+  let RenderMethod = "addMemOperands";
+  let ParserMethod = "parseMemOperand";
+  let PredicateMethod = "isMemWithUimmOffsetSP<6>";
+}
+
+def mem_mm_4sp : Operand<i32> {
+  let PrintMethod = "printMemOperand";
+  let MIOperandInfo = (ops GPR32, uimm8);
+  let EncoderMethod = "getMemEncodingMMImm4sp";
+  let ParserMatchClass = MipsMemUimm4AsmOperand;
+  let OperandType = "OPERAND_MEMORY";
+}
+
 def jmptarget_mm : Operand<OtherVT> {
   let EncoderMethod = "getJumpTargetOpValueMM";
 }
 
 def calltarget_mm : Operand<iPTR> {
   let EncoderMethod = "getJumpTargetOpValueMM";
 }
 

 }
 
 class StoreMM16<string opstr, DAGOperand RTOpnd, DAGOperand RO,
                 SDPatternOperator OpNode, InstrItinClass Itin,
                 Operand MemOpnd> :
   MicroMipsInst16<(outs), (ins RTOpnd:$rt, MemOpnd:$addr),
                   !strconcat(opstr, "\t$rt, $addr"), [], Itin, FrmI> {
   let mayStore = 1;
 }
 
 class AddImmUR2<string opstr, RegisterOperand RO> :
   MicroMipsInst16<(outs RO:$rd), (ins RO:$rs, simm3_lsa2:$imm),
                   !strconcat(opstr, "\t$rd, $rs, $imm"),
                   [], NoItinerary, FrmR> {
   let isCommutable = 1;
 }
 

 
 def reglist : Operand<i32> {
   let EncoderMethod = "getRegisterListOpValue";
   let ParserMatchClass = RegListAsmOperand;
   let PrintMethod = "printRegisterList";
   let DecoderMethod = "DecodeRegListOperand";
 }
 
+def RegList16AsmOperand : AsmOperandClass {
+  let Name = "RegList16";
+  let ParserMethod = "parseRegisterList";
+  let PredicateMethod = "isRegList16";
+  let RenderMethod = "addRegListOperands";
+}
+
+def reglist16 : Operand<i32> {
+  let EncoderMethod = "getRegisterListOpValue16";
+  let DecoderMethod = "DecodeRegListOperand16";
+  let PrintMethod = "printRegisterList";
+  let ParserMatchClass = RegList16AsmOperand;
+}
+
 class StoreMultMM<string opstr,
             InstrItinClass Itin = NoItinerary, ComplexPattern Addr = addr> :
   InstSE<(outs), (ins reglist:$rt, mem_mm_12:$addr),
          !strconcat(opstr, "\t$rt, $addr"), [], Itin, FrmI, opstr> {
   let DecoderMethod = "DecodeMemMMImm12";
   let mayStore = 1;
 }
 
 class LoadMultMM<string opstr,
             InstrItinClass Itin = NoItinerary, ComplexPattern Addr = addr> :
   InstSE<(outs reglist:$rt), (ins mem_mm_12:$addr),
           !strconcat(opstr, "\t$rt, $addr"), [], Itin, FrmI, opstr> {
   let DecoderMethod = "DecodeMemMMImm12";
   let mayLoad = 1;
 }
 
+class StoreMultMM16<string opstr,
+            InstrItinClass Itin = NoItinerary, ComplexPattern Addr = addr> :
+  MicroMipsInst16<(outs), (ins reglist16:$rt, mem_mm_4sp:$addr),
+                  !strconcat(opstr, "\t$rt, $addr"), [], Itin, FrmI> {
+  let mayStore = 1;
+}
+
+class LoadMultMM16<string opstr,
+            InstrItinClass Itin = NoItinerary, ComplexPattern Addr = addr> :
+  MicroMipsInst16<(outs reglist16:$rt), (ins mem_mm_4sp:$addr),
+                  !strconcat(opstr, "\t$rt, $addr"), [], Itin, FrmI> {
+  let mayLoad = 1;
+}
+
 def ADDU16_MM : ArithRMM16<"addu16", GPRMM16Opnd, 1, II_ADDU, add>,
                 ARITH_FM_MM16<0>;
 def SUBU16_MM : ArithRMM16<"subu16", GPRMM16Opnd, 0, II_SUBU, sub>,
                 ARITH_FM_MM16<1>;
 def ANDI16_MM : AndImmMM16<"andi16", GPRMM16Opnd, II_AND>, ANDI_FM_MM16<0x0b>;
 def AND16_MM : LogicRMM16<"and16", GPRMM16Opnd, II_AND, and>,
                LOGIC_FM_MM16<0x2>;
 def OR16_MM  : LogicRMM16<"or16", GPRMM16Opnd, II_OR, or>,
let DecoderNamespace = "MicroMips", Predicates = [InMicroMips] in {
   def SWL_MM : StoreLeftRightMM<"swl", MipsSWL, GPR32Opnd, mem_mm_12>,
                LWL_FM_MM<0x8>;
   def SWR_MM : StoreLeftRightMM<"swr", MipsSWR, GPR32Opnd, mem_mm_12>,
                LWL_FM_MM<0x9>;
 
   /// Load and Store Instructions - multiple
   def SWM32_MM  : StoreMultMM<"swm32">, LWM_FM_MM<0xd>;
   def LWM32_MM  : LoadMultMM<"lwm32">, LWM_FM_MM<0x5>;
+  def SWM16_MM : StoreMultMM16<"swm16">, LWM_FM_MM16<0x5>;
+  def LWM16_MM : LoadMultMM16<"lwm16">, LWM_FM_MM16<0x4>;
 
   /// Move Conditional
   def MOVZ_I_MM : MMRel, CMov_I_I_FT<"movz", GPR32Opnd, GPR32Opnd,
                   NoItinerary>, ADD_FM_MM<0, 0x58>;
   def MOVN_I_MM : MMRel, CMov_I_I_FT<"movn", GPR32Opnd, GPR32Opnd,
                   NoItinerary>, ADD_FM_MM<0, 0x18>;
   def MOVT_I_MM : MMRel, CMov_F_I_FT<"movt", GPR32Opnd, II_MOVT>,
                   CMov_F_I_FM_MM<0x25>;

test/MC/Mips/micromips-invalid.s

# RUN: FileCheck %s < %t1
   sll16   $1, $16, 5 # CHECK: :[[@LINE]]:{{[0-9]+}}: error: invalid operand for instruction
   srl16   $4, $9, 6  # CHECK: :[[@LINE]]:{{[0-9]+}}: error: invalid operand for instruction
   sll16   $3, $16, 9 # CHECK: :[[@LINE]]:{{[0-9]+}}: error: immediate operand value out of range
   srl16   $4, $5, 15 # CHECK: :[[@LINE]]:{{[0-9]+}}: error: immediate operand value out of range
   li16  $8, -1 # CHECK: :[[@LINE]]:{{[0-9]+}}: error: invalid operand for instruction
   li16  $4, -2 # CHECK: :[[@LINE]]:{{[0-9]+}}: error: immediate operand value out of range
   addiur2 $9, $7, -1 # CHECK: :[[@LINE]]:{{[0-9]+}}: error: invalid operand for instruction
   addiur2 $6, $7, 10 # CHECK: :[[@LINE]]:{{[0-9]+}}: error: immediate operand value out of range
+  lwm16   $5, $6, $ra, 8($sp)    # CHECK: :[[@LINE]]:{{[0-9]+}}: error: $16 or $31 expected
+  lwm16   $16, $19, $ra, 8($sp)  # CHECK: :[[@LINE]]:{{[0-9]+}}: error: consecutive register numbers expected
+  lwm16   $16-$25, $ra, 8($sp)   # CHECK: :[[@LINE]]:{{[0-9]+}}: error: invalid register operand
+  lwm16   $16, 8($sp)            # CHECK: :[[@LINE]]:{{[0-9]+}}: error: invalid operand for instruction
+  lwm16   $16, $17, 8($sp)       # CHECK: :[[@LINE]]:{{[0-9]+}}: error: invalid operand for instruction
+  lwm16   $16-$20, 8($sp)        # CHECK: :[[@LINE]]:{{[0-9]+}}: error: invalid operand for instruction
+  swm16   $5, $6, $ra, 8($sp)    # CHECK: :[[@LINE]]:{{[0-9]+}}: error: $16 or $31 expected
+  swm16   $16, $19, $ra, 8($sp)  # CHECK: :[[@LINE]]:{{[0-9]+}}: error: consecutive register numbers expected
+  swm16   $16-$25, $ra, 8($sp)   # CHECK: :[[@LINE]]:{{[0-9]+}}: error: invalid register operand
   lwm32   $5, $6, 8($4)    # CHECK: :[[@LINE]]:{{[0-9]+}}: error: $16 or $31 expected
   lwm32   $16, $19, 8($4)  # CHECK: :[[@LINE]]:{{[0-9]+}}: error: consecutive register numbers expected
   lwm32   $16-$25, 8($4)   # CHECK: :[[@LINE]]:{{[0-9]+}}: error: invalid register operand
   swm32   $5, $6, 8($4)    # CHECK: :[[@LINE]]:{{[0-9]+}}: error: $16 or $31 expected
   swm32   $16, $19, 8($4)  # CHECK: :[[@LINE]]:{{[0-9]+}}: error: consecutive register numbers expected
   swm32   $16-$25, 8($4)   # CHECK: :[[@LINE]]:{{[0-9]+}}: error: invalid register operand
   lwm32 $16, $17, $18, $19, $20, $21, $22, $23, $24, 8($4) # CHECK: :[[@LINE]]:{{[0-9]+}}: error: invalid register operand
   lbu16 $9, 8($16) # CHECK: :[[@LINE]]:{{[0-9]+}}: error: invalid operand for instruction

test/MC/Mips/micromips-loadstore-instructions.s

 # CHECK-EL: lwm32  $16, $17, 8($4)            # encoding: [0x44,0x20,0x08,0x50]
 # CHECK-EL: lwm32  $16, $17, $18, $19, 8($4)  # encoding: [0x84,0x20,0x08,0x50]
 # CHECK-EL: lwm32  $16, $17, $18, $19, $20, $21, $22, $23, $fp, 8($4)      # encoding: [0x24,0x21,0x08,0x50]
 # CHECK-EL: lwm32  $16, $17, $18, $19, $ra, 8($4)                          # encoding: [0x84,0x22,0x08,0x50]
 # CHECK-EL: lwm32  $16, $17, $18, $19, $20, $21, $22, $23, $fp, $ra, 8($4) # encoding: [0x24,0x23,0x08,0x50]
 # CHECK-EL: lwm32  $16, $17, $18, $19, $20, $21, $22, $23, $fp, $ra, 8($4) # encoding: [0x24,0x23,0x08,0x50]
 # CHECK-EL: swm32  $16, $17, 8($4)            # encoding: [0x44,0x20,0x08,0xd0]
 # CHECK-EL: swm32  $16, $17, $18, $19, 8($4)  # encoding: [0x84,0x20,0x08,0xd0]
+# CHECK-EL: lwm16  $16, $17, $ra, 8($sp)      # encoding: [0x12,0x45]
+# CHECK-EL: swm16  $16, $17, $ra, 8($sp)      # encoding: [0x52,0x45]
 #------------------------------------------------------------------------------
 # Big endian
 #------------------------------------------------------------------------------
 # CHECK-EB: lb     $5, 8($4)                 # encoding: [0x1c,0xa4,0x00,0x08]
 # CHECK-EB: lbu    $6, 8($4)                 # encoding: [0x14,0xc4,0x00,0x08]
 # CHECK-EB: lh     $2, 8($4)                 # encoding: [0x3c,0x44,0x00,0x08]
 # CHECK-EB: lhu    $4, 8($2)                 # encoding: [0x34,0x82,0x00,0x08]
 # CHECK-EB: lw     $6, 4($5)                 # encoding: [0xfc,0xc5,0x00,0x04]
 # CHECK-EB: sb     $5, 8($4)                 # encoding: [0x18,0xa4,0x00,0x08]
 # CHECK-EB: sh     $2, 8($4)                 # encoding: [0x38,0x44,0x00,0x08]
 # CHECK-EB: sw     $5, 4($6)                 # encoding: [0xf8,0xa6,0x00,0x04]
 # CHECK-EB: ll     $2, 8($4)                 # encoding: [0x60,0x44,0x30,0x08]
 # CHECK-EB: sc     $2, 8($4)                 # encoding: [0x60,0x44,0xb0,0x08]
 # CHECK-EB: lwu    $2, 8($4)                 # encoding: [0x60,0x44,0xe0,0x08]
 # CHECK-EB: lwxs   $2, $3($4)                # encoding: [0x00,0x64,0x11,0x18]
 # CHECK-EB: lwm32  $16, $17, 8($4)           # encoding: [0x20,0x44,0x50,0x08]
 # CHECK-EB: lwm32  $16, $17, $18, $19, 8($4) # encoding: [0x20,0x84,0x50,0x08]
 # CHECK-EB: lwm32  $16, $17, $18, $19, $20, $21, $22, $23, $fp, 8($4)      # encoding: [0x21,0x24,0x50,0x08]
 # CHECK-EB: lwm32  $16, $17, $18, $19, $ra, 8($4)                          # encoding: [0x22,0x84,0x50,0x08]
 # CHECK-EB: lwm32  $16, $17, $18, $19, $20, $21, $22, $23, $fp, $ra, 8($4) # encoding: [0x23,0x24,0x50,0x08]
 # CHECK-EB: lwm32  $16, $17, $18, $19, $20, $21, $22, $23, $fp, $ra, 8($4) # encoding: [0x23,0x24,0x50,0x08]
 # CHECK-EB: swm32  $16, $17, 8($4)           # encoding: [0x20,0x44,0xd0,0x08]
 # CHECK-EB: swm32  $16, $17, $18, $19, 8($4) # encoding: [0x20,0x84,0xd0,0x08]
+# CHECK-EB: lwm16  $16, $17, $ra, 8($sp)     # encoding: [0x45,0x12]
+# CHECK-EB: swm16  $16, $17, $ra, 8($sp)     # encoding: [0x45,0x52]
      lb     $5, 8($4)
      lbu    $6, 8($4)
      lh     $2, 8($4)
      lhu    $4, 8($2)
      lw     $6, 4($5)
      sb     $5, 8($4)
      sh     $2, 8($4)
      sw     $5, 4($6)
      ll     $2, 8($4)
      sc     $2, 8($4)
      lwu    $2, 8($4)
      lwxs   $2, $3($4)
      lwm32  $16, $17, 8($4)
      lwm32  $16 - $19, 8($4)
      lwm32  $16-$23, $30, 8($4)
      lwm32  $16-$19, $31, 8($4)
      lwm32  $16-$23, $30, $31, 8($4)
      lwm32  $16-$23, $30 - $31, 8($4)
      swm32  $16, $17, 8($4)
      swm32  $16 - $19, 8($4)
+     lwm16  $16, $17, $ra, 8($sp)
+     swm16  $16, $17, $ra, 8($sp)