1 //===-- MipsISelLowering.cpp - Mips DAG Lowering Implementation -----------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by Bruno Cardoso Lopes and is distributed under the
6 // University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the interfaces that Mips uses to lower LLVM code into a
13 //===----------------------------------------------------------------------===//
15 #define DEBUG_TYPE "mips-lower"
17 #include "MipsISelLowering.h"
18 #include "MipsTargetMachine.h"
19 #include "llvm/DerivedTypes.h"
20 #include "llvm/Function.h"
21 #include "llvm/Intrinsics.h"
22 #include "llvm/CallingConv.h"
23 #include "llvm/ADT/VectorExtras.h"
24 #include "llvm/CodeGen/CallingConvLower.h"
25 #include "llvm/CodeGen/MachineFrameInfo.h"
26 #include "llvm/CodeGen/MachineFunction.h"
27 #include "llvm/CodeGen/MachineInstrBuilder.h"
28 #include "llvm/CodeGen/SelectionDAGISel.h"
29 #include "llvm/CodeGen/SSARegMap.h"
30 #include "llvm/CodeGen/ValueTypes.h"
31 #include "llvm/Support/Debug.h"
37 const char *MipsTargetLowering::
38 getTargetNodeName(unsigned Opcode) const
42 case MipsISD::JmpLink : return "MipsISD::JmpLink";
43 case MipsISD::Hi : return "MipsISD::Hi";
44 case MipsISD::Lo : return "MipsISD::Lo";
45 case MipsISD::Ret : return "MipsISD::Ret";
46 case MipsISD::Add : return "MipsISD::Add";
47 default : return NULL;
52 MipsTargetLowering(MipsTargetMachine &TM): TargetLowering(TM)
54 // Mips does not have i1 type, so use i32 for
55 // setcc operations results (slt, sgt, ...).
56 setSetCCResultType(MVT::i32);
57 setSetCCResultContents(ZeroOrOneSetCCResult);
59 // Set up the register classes
60 addRegisterClass(MVT::i32, Mips::CPURegsRegisterClass);
63 setOperationAction(ISD::GlobalAddress, MVT::i32, Custom);
64 setOperationAction(ISD::GlobalTLSAddress, MVT::i32, Custom);
65 setOperationAction(ISD::RET, MVT::Other, Custom);
67 // Load extented operations for i1 types must be promoted
68 setLoadXAction(ISD::EXTLOAD, MVT::i1, Promote);
69 setLoadXAction(ISD::ZEXTLOAD, MVT::i1, Promote);
70 setLoadXAction(ISD::SEXTLOAD, MVT::i1, Promote);
72 // Store operations for i1 types must be promoted
73 setStoreXAction(MVT::i1, Promote);
75 // Mips does not have these NodeTypes below.
76 setOperationAction(ISD::BR_JT, MVT::Other, Expand);
77 setOperationAction(ISD::BR_CC, MVT::Other, Expand);
78 setOperationAction(ISD::SELECT_CC, MVT::Other, Expand);
79 setOperationAction(ISD::SIGN_EXTEND_INREG, MVT::i1, Expand);
80 setOperationAction(ISD::SELECT, MVT::i32, Expand);
82 // Mips not supported intrinsics.
83 setOperationAction(ISD::MEMMOVE, MVT::Other, Expand);
84 setOperationAction(ISD::MEMSET, MVT::Other, Expand);
85 setOperationAction(ISD::MEMCPY, MVT::Other, Expand);
87 setOperationAction(ISD::CTPOP, MVT::i32, Expand);
88 setOperationAction(ISD::CTTZ , MVT::i32, Expand);
89 setOperationAction(ISD::CTLZ , MVT::i32, Expand);
90 setOperationAction(ISD::ROTL , MVT::i32, Expand);
91 setOperationAction(ISD::ROTR , MVT::i32, Expand);
92 setOperationAction(ISD::BSWAP, MVT::i32, Expand);
94 setOperationAction(ISD::SHL_PARTS, MVT::i32, Expand);
95 setOperationAction(ISD::SRA_PARTS, MVT::i32, Expand);
96 setOperationAction(ISD::SRL_PARTS, MVT::i32, Expand);
98 // We don't have line number support yet.
99 setOperationAction(ISD::LOCATION, MVT::Other, Expand);
100 setOperationAction(ISD::DEBUG_LOC, MVT::Other, Expand);
101 setOperationAction(ISD::LABEL, MVT::Other, Expand);
103 // Use the default for now
104 setOperationAction(ISD::STACKSAVE, MVT::Other, Expand);
105 setOperationAction(ISD::STACKRESTORE, MVT::Other, Expand);
107 setOperationAction(ISD::ADJUST_TRAMP, MVT::i32, Expand);
109 setStackPointerRegisterToSaveRestore(Mips::SP);
110 computeRegisterProperties();
114 SDOperand MipsTargetLowering::
115 LowerOperation(SDOperand Op, SelectionDAG &DAG)
117 switch (Op.getOpcode())
119 case ISD::CALL: return LowerCALL(Op, DAG);
120 case ISD::FORMAL_ARGUMENTS: return LowerFORMAL_ARGUMENTS(Op, DAG);
121 case ISD::RET: return LowerRET(Op, DAG);
122 case ISD::GlobalAddress: return LowerGlobalAddress(Op, DAG);
123 case ISD::GlobalTLSAddress: return LowerGlobalTLSAddress(Op, DAG);
128 //===----------------------------------------------------------------------===//
129 // Lower helper functions
130 //===----------------------------------------------------------------------===//
132 // AddLiveIn - This helper function adds the specified physical register to the
133 // MachineFunction as a live in value. It also creates a corresponding
134 // virtual register for it.
136 AddLiveIn(MachineFunction &MF, unsigned PReg, TargetRegisterClass *RC)
138 assert(RC->contains(PReg) && "Not the correct regclass!");
139 unsigned VReg = MF.getSSARegMap()->createVirtualRegister(RC);
140 MF.addLiveIn(PReg, VReg);
144 //===----------------------------------------------------------------------===//
145 // Misc Lower Operation implementation
146 //===----------------------------------------------------------------------===//
147 SDOperand MipsTargetLowering::
148 LowerGlobalAddress(SDOperand Op, SelectionDAG &DAG)
150 GlobalValue *GV = cast<GlobalAddressSDNode>(Op)->getGlobal();
152 SDOperand GA = DAG.getTargetGlobalAddress(GV, MVT::i32);
154 const MVT::ValueType *VTs = DAG.getNodeValueTypes(MVT::i32, MVT::Flag);
155 SDOperand Ops[] = { GA };
157 SDOperand Hi = DAG.getNode(MipsISD::Hi, VTs, 2, Ops, 1);
158 SDOperand Lo = DAG.getNode(MipsISD::Lo, MVT::i32, GA);
160 SDOperand InFlag = Hi.getValue(1);
161 return DAG.getNode(MipsISD::Add, MVT::i32, Lo, Hi, InFlag);
164 SDOperand MipsTargetLowering::
165 LowerGlobalTLSAddress(SDOperand Op, SelectionDAG &DAG)
167 assert(0 && "TLS not implemented for MIPS.");
170 //===----------------------------------------------------------------------===//
171 // Calling Convention Implementation
173 // The lower operations present on calling convention works on this order:
174 // LowerCALL (virt regs --> phys regs, virt regs --> stack)
175 // LowerFORMAL_ARGUMENTS (phys --> virt regs, stack --> virt regs)
176 // LowerRET (virt regs --> phys regs)
177 // LowerCALL (phys regs --> virt regs)
179 //===----------------------------------------------------------------------===//
181 #include "MipsGenCallingConv.inc"
183 //===----------------------------------------------------------------------===//
184 // CALL Calling Convention Implementation
185 //===----------------------------------------------------------------------===//
187 /// Mips custom CALL implementation
188 SDOperand MipsTargetLowering::
189 LowerCALL(SDOperand Op, SelectionDAG &DAG)
191 unsigned CallingConv= cast<ConstantSDNode>(Op.getOperand(1))->getValue();
193 // By now, only CallingConv::C implemented
197 assert(0 && "Unsupported calling convention");
198 case CallingConv::Fast:
200 return LowerCCCCallTo(Op, DAG, CallingConv);
204 /// LowerCCCCallTo - functions arguments are copied from virtual
205 /// regs to (physical regs)/(stack frame), CALLSEQ_START and
206 /// CALLSEQ_END are emitted.
207 /// TODO: isVarArg, isTailCall, sret, GOT, linkage types.
208 SDOperand MipsTargetLowering::
209 LowerCCCCallTo(SDOperand Op, SelectionDAG &DAG, unsigned CC)
211 MachineFunction &MF = DAG.getMachineFunction();
212 unsigned StackReg = MF.getTarget().getRegisterInfo()->getFrameRegister(MF);
214 SDOperand Chain = Op.getOperand(0);
215 SDOperand Callee = Op.getOperand(4);
216 bool isVarArg = cast<ConstantSDNode>(Op.getOperand(2))->getValue() != 0;
218 MachineFrameInfo *MFI = MF.getFrameInfo();
220 // Analyze operands of the call, assigning locations to each operand.
221 SmallVector<CCValAssign, 16> ArgLocs;
222 CCState CCInfo(CC, isVarArg, getTargetMachine(), ArgLocs);
224 // To meet ABI, Mips must always allocate 16 bytes on
225 // the stack (even if less than 4 are used as arguments)
226 int VTsize = MVT::getSizeInBits(MVT::i32)/8;
227 MFI->CreateFixedObject(VTsize, -(VTsize*3));
229 CCInfo.AnalyzeCallOperands(Op.Val, CC_Mips);
231 // Get a count of how many bytes are to be pushed on the stack.
232 unsigned NumBytes = CCInfo.getNextStackOffset();
233 Chain = DAG.getCALLSEQ_START(Chain,DAG.getConstant(NumBytes,
236 SmallVector<std::pair<unsigned, SDOperand>, 8> RegsToPass;
237 SmallVector<SDOperand, 8> MemOpChains;
241 // Walk the register/memloc assignments, inserting copies/loads.
242 for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
243 CCValAssign &VA = ArgLocs[i];
245 // Arguments start after the 5 first operands of ISD::CALL
246 SDOperand Arg = Op.getOperand(5+2*VA.getValNo());
248 // Promote the value if needed.
249 switch (VA.getLocInfo()) {
250 default: assert(0 && "Unknown loc info!");
251 case CCValAssign::Full: break;
252 case CCValAssign::SExt:
253 Arg = DAG.getNode(ISD::SIGN_EXTEND, VA.getLocVT(), Arg);
255 case CCValAssign::ZExt:
256 Arg = DAG.getNode(ISD::ZERO_EXTEND, VA.getLocVT(), Arg);
258 case CCValAssign::AExt:
259 Arg = DAG.getNode(ISD::ANY_EXTEND, VA.getLocVT(), Arg);
263 // Arguments that can be passed on register,
264 // must be kept at RegsToPass vector
266 RegsToPass.push_back(std::make_pair(VA.getLocReg(), Arg));
269 assert(VA.isMemLoc());
271 if (StackPtr.Val == 0)
272 StackPtr = DAG.getRegister(StackReg, getPointerTy());
274 // Create the frame index object for this incoming parameter
275 // This guarantees that when allocating Local Area our room
276 // will not be overwritten.
277 int FI = MFI->CreateFixedObject(MVT::getSizeInBits(VA.getValVT())/8,
278 -(16 + VA.getLocMemOffset()) );
280 SDOperand PtrOff = DAG.getFrameIndex(FI,getPointerTy());
282 // emit ISD::STORE whichs stores the
283 // parameter value to a stack Location
284 MemOpChains.push_back(DAG.getStore(Chain, Arg, PtrOff, NULL, 0));
288 // Transform all store nodes into one single node because
289 // all store nodes are independent of each other.
290 if (!MemOpChains.empty())
291 Chain = DAG.getNode(ISD::TokenFactor, MVT::Other,
292 &MemOpChains[0], MemOpChains.size());
294 // Build a sequence of copy-to-reg nodes chained together with token
295 // chain and flag operands which copy the outgoing args into registers.
296 // The InFlag in necessary since all emited instructions must be
299 for (unsigned i = 0, e = RegsToPass.size(); i != e; ++i) {
300 Chain = DAG.getCopyToReg(Chain, RegsToPass[i].first,
301 RegsToPass[i].second, InFlag);
302 InFlag = Chain.getValue(1);
305 // If the callee is a GlobalAddress node (quite common, every direct
306 // call is) turn it into a TargetGlobalAddress node so that legalize
308 if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee)) {
309 Callee = DAG.getTargetGlobalAddress(G->getGlobal(), getPointerTy());
311 if (ExternalSymbolSDNode *S = dyn_cast<ExternalSymbolSDNode>(Callee))
312 Callee = DAG.getTargetExternalSymbol(S->getSymbol(), getPointerTy());
314 // MipsJmpLink = #chain, #target_address, #opt_in_flags...
315 // = Chain, Callee, Reg#1, Reg#2, ...
317 // Returns a chain & a flag for retval copy to use.
318 SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Flag);
319 SmallVector<SDOperand, 8> Ops;
320 Ops.push_back(Chain);
321 Ops.push_back(Callee);
323 // Add argument registers to the end of the list so that they are
324 // known live into the call.
325 for (unsigned i = 0, e = RegsToPass.size(); i != e; ++i)
326 Ops.push_back(DAG.getRegister(RegsToPass[i].first,
327 RegsToPass[i].second.getValueType()));
330 Ops.push_back(InFlag);
332 Chain = DAG.getNode(MipsISD::JmpLink, NodeTys, &Ops[0], Ops.size());
333 InFlag = Chain.getValue(1);
335 // Create the CALLSEQ_END node.
336 NodeTys = DAG.getVTList(MVT::Other, MVT::Flag);
338 Ops.push_back(Chain);
339 Ops.push_back(DAG.getConstant(NumBytes, getPointerTy()));
340 Ops.push_back(InFlag);
341 Chain = DAG.getNode(ISD::CALLSEQ_END, NodeTys, &Ops[0], Ops.size());
342 InFlag = Chain.getValue(1);
344 // Handle result values, copying them out of physregs into vregs that we
346 return SDOperand(LowerCallResult(Chain, InFlag, Op.Val, CC, DAG), Op.ResNo);
349 /// LowerCallResult - Lower the result values of an ISD::CALL into the
350 /// appropriate copies out of appropriate physical registers. This assumes that
351 /// Chain/InFlag are the input chain/flag to use, and that TheCall is the call
352 /// being lowered. Returns a SDNode with the same number of values as the
354 SDNode *MipsTargetLowering::
355 LowerCallResult(SDOperand Chain, SDOperand InFlag, SDNode *TheCall,
356 unsigned CallingConv, SelectionDAG &DAG) {
358 bool isVarArg = cast<ConstantSDNode>(TheCall->getOperand(2))->getValue() != 0;
360 // Assign locations to each value returned by this call.
361 SmallVector<CCValAssign, 16> RVLocs;
362 CCState CCInfo(CallingConv, isVarArg, getTargetMachine(), RVLocs);
364 CCInfo.AnalyzeCallResult(TheCall, RetCC_Mips);
365 SmallVector<SDOperand, 8> ResultVals;
368 //if (!RVLocs.size())
371 // Copy all of the result registers out of their specified physreg.
372 for (unsigned i = 0; i != RVLocs.size(); ++i) {
373 Chain = DAG.getCopyFromReg(Chain, RVLocs[i].getLocReg(),
374 RVLocs[i].getValVT(), InFlag).getValue(1);
375 InFlag = Chain.getValue(2);
376 ResultVals.push_back(Chain.getValue(0));
379 // Merge everything together with a MERGE_VALUES node.
380 ResultVals.push_back(Chain);
381 return DAG.getNode(ISD::MERGE_VALUES, TheCall->getVTList(),
382 &ResultVals[0], ResultVals.size()).Val;
385 //===----------------------------------------------------------------------===//
386 // FORMAL_ARGUMENTS Calling Convention Implementation
387 //===----------------------------------------------------------------------===//
389 /// Mips custom FORMAL_ARGUMENTS implementation
390 SDOperand MipsTargetLowering::
391 LowerFORMAL_ARGUMENTS(SDOperand Op, SelectionDAG &DAG)
393 unsigned CC = cast<ConstantSDNode>(Op.getOperand(1))->getValue();
397 assert(0 && "Unsupported calling convention");
399 return LowerCCCArguments(Op, DAG);
403 /// LowerCCCArguments - transform physical registers into
404 /// virtual registers and generate load operations for
405 /// arguments places on the stack.
406 /// TODO: isVarArg, sret
407 SDOperand MipsTargetLowering::
408 LowerCCCArguments(SDOperand Op, SelectionDAG &DAG)
410 SDOperand Root = Op.getOperand(0);
411 MachineFunction &MF = DAG.getMachineFunction();
412 MachineFrameInfo *MFI = MF.getFrameInfo();
414 bool isVarArg = cast<ConstantSDNode>(Op.getOperand(2))->getValue() != 0;
415 unsigned CC = DAG.getMachineFunction().getFunction()->getCallingConv();
417 unsigned StackReg = MF.getTarget().getRegisterInfo()->getFrameRegister(MF);
419 // Assign locations to all of the incoming arguments.
420 SmallVector<CCValAssign, 16> ArgLocs;
421 CCState CCInfo(CC, isVarArg, getTargetMachine(), ArgLocs);
423 CCInfo.AnalyzeFormalArguments(Op.Val, CC_Mips);
424 SmallVector<SDOperand, 8> ArgValues;
427 for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
429 CCValAssign &VA = ArgLocs[i];
431 // Arguments stored on registers
433 MVT::ValueType RegVT = VA.getLocVT();
434 TargetRegisterClass *RC;
436 if (RegVT == MVT::i32)
437 RC = Mips::CPURegsRegisterClass;
439 assert(0 && "support only Mips::CPURegsRegisterClass");
442 // Transform the arguments stored on
443 // physical registers into virtual ones
444 unsigned Reg = AddLiveIn(DAG.getMachineFunction(), VA.getLocReg(), RC);
445 SDOperand ArgValue = DAG.getCopyFromReg(Root, Reg, RegVT);
447 // If this is an 8 or 16-bit value, it is really passed promoted
448 // to 32 bits. Insert an assert[sz]ext to capture this, then
449 // truncate to the right size.
450 if (VA.getLocInfo() == CCValAssign::SExt)
451 ArgValue = DAG.getNode(ISD::AssertSext, RegVT, ArgValue,
452 DAG.getValueType(VA.getValVT()));
453 else if (VA.getLocInfo() == CCValAssign::ZExt)
454 ArgValue = DAG.getNode(ISD::AssertZext, RegVT, ArgValue,
455 DAG.getValueType(VA.getValVT()));
457 if (VA.getLocInfo() != CCValAssign::Full)
458 ArgValue = DAG.getNode(ISD::TRUNCATE, VA.getValVT(), ArgValue);
460 ArgValues.push_back(ArgValue);
462 // To meet ABI, when VARARGS are passed on registers, the registers
463 // containt must be written to the their always reserved home location
467 if (StackPtr.Val == 0)
468 StackPtr = DAG.getRegister(StackReg, getPointerTy());
470 // Create the frame index object for this incoming parameter
471 // The first 16 bytes are reserved.
472 int FI = MFI->CreateFixedObject(MVT::getSizeInBits(VA.getValVT())/8,
474 SDOperand PtrOff = DAG.getFrameIndex(FI, getPointerTy());
476 // emit ISD::STORE whichs stores the
477 // parameter value to a stack Location
478 ArgValues.push_back(DAG.getStore(Root, ArgValue, PtrOff, NULL, 0));
483 assert(VA.isMemLoc());
485 // Create the frame index object for this incoming parameter...
486 int FI = MFI->CreateFixedObject(MVT::getSizeInBits(VA.getValVT())/8,
487 (16 + VA.getLocMemOffset()));
489 // Create load nodes to retrieve arguments from the stack
490 SDOperand FIN = DAG.getFrameIndex(FI, getPointerTy());
491 ArgValues.push_back(DAG.getLoad(VA.getValVT(), Root, FIN, NULL, 0));
494 ArgValues.push_back(Root);
496 // Return the new list of results.
497 return DAG.getNode(ISD::MERGE_VALUES, Op.Val->getVTList(),
498 &ArgValues[0], ArgValues.size()).getValue(Op.ResNo);
501 //===----------------------------------------------------------------------===//
502 // Return Value Calling Convention Implementation
503 //===----------------------------------------------------------------------===//
505 SDOperand MipsTargetLowering::
506 LowerRET(SDOperand Op, SelectionDAG &DAG)
508 // CCValAssign - represent the assignment of
509 // the return value to a location
510 SmallVector<CCValAssign, 16> RVLocs;
511 unsigned CC = DAG.getMachineFunction().getFunction()->getCallingConv();
512 bool isVarArg = DAG.getMachineFunction().getFunction()->isVarArg();
514 // CCState - Info about the registers and stack slot.
515 CCState CCInfo(CC, isVarArg, getTargetMachine(), RVLocs);
517 // Analize return values of ISD::RET
518 CCInfo.AnalyzeReturn(Op.Val, RetCC_Mips);
520 // If this is the first return lowered for this function, add
521 // the regs to the liveout set for the function.
522 if (DAG.getMachineFunction().liveout_empty()) {
523 for (unsigned i = 0; i != RVLocs.size(); ++i)
524 if (RVLocs[i].isRegLoc())
525 DAG.getMachineFunction().addLiveOut(RVLocs[i].getLocReg());
528 // The chain is always operand #0
529 SDOperand Chain = Op.getOperand(0);
532 // Copy the result values into the output registers.
533 for (unsigned i = 0; i != RVLocs.size(); ++i) {
534 CCValAssign &VA = RVLocs[i];
535 assert(VA.isRegLoc() && "Can only return in registers!");
537 // ISD::RET => ret chain, (regnum1,val1), ...
538 // So i*2+1 index only the regnums
539 Chain = DAG.getCopyToReg(Chain, VA.getLocReg(),
540 Op.getOperand(i*2+1), Flag);
542 // guarantee that all emitted copies are
543 // stuck together, avoiding something bad
544 Flag = Chain.getValue(1);
547 // Return on Mips is always a "jr $ra"
549 return DAG.getNode(MipsISD::Ret, MVT::Other,
550 Chain, DAG.getRegister(Mips::RA, MVT::i32), Flag);
552 return DAG.getNode(MipsISD::Ret, MVT::Other,
553 Chain, DAG.getRegister(Mips::RA, MVT::i32));
556 //===----------------------------------------------------------------------===//
557 // Mips Inline Assembly Support
558 //===----------------------------------------------------------------------===//
560 /// getConstraintType - Given a constraint letter, return the type of
561 /// constraint it is for this target.
562 MipsTargetLowering::ConstraintType MipsTargetLowering::
563 getConstraintType(const std::string &Constraint) const
565 if (Constraint.size() == 1) {
566 // Mips specific constrainy
567 // GCC config/mips/constraints.md
569 // 'd' : An address register. Equivalent to r
570 // unless generating MIPS16 code.
571 // 'y' : Equivalent to r; retained for
572 // backwards compatibility.
574 switch (Constraint[0]) {
578 return C_RegisterClass;
582 return TargetLowering::getConstraintType(Constraint);
585 std::pair<unsigned, const TargetRegisterClass*> MipsTargetLowering::
586 getRegForInlineAsmConstraint(const std::string &Constraint,
587 MVT::ValueType VT) const
589 if (Constraint.size() == 1) {
590 switch (Constraint[0]) {
592 return std::make_pair(0U, Mips::CPURegsRegisterClass);
596 return TargetLowering::getRegForInlineAsmConstraint(Constraint, VT);
599 std::vector<unsigned> MipsTargetLowering::
600 getRegClassForInlineAsmConstraint(const std::string &Constraint,
601 MVT::ValueType VT) const
603 if (Constraint.size() != 1)
604 return std::vector<unsigned>();
606 switch (Constraint[0]) {
609 // GCC Mips Constraint Letters
612 return make_vector<unsigned>(Mips::V0, Mips::V1, Mips::A0,
613 Mips::A1, Mips::A2, Mips::A3,
614 Mips::T0, Mips::T1, Mips::T2,
615 Mips::T3, Mips::T4, Mips::T5,
616 Mips::T6, Mips::T7, Mips::S0,
617 Mips::S1, Mips::S2, Mips::S3,
618 Mips::S4, Mips::S5, Mips::S6,
619 Mips::S7, Mips::T8, Mips::T9, 0);
622 return std::vector<unsigned>();