1 //===-- ARMISelDAGToDAG.cpp - A dag to dag inst selector for ARM ----------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by Chris Lattner and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines an instruction selector for the ARM target.
12 //===----------------------------------------------------------------------===//
15 #include "ARMTargetMachine.h"
16 #include "llvm/CallingConv.h"
17 #include "llvm/DerivedTypes.h"
18 #include "llvm/Function.h"
19 #include "llvm/Intrinsics.h"
20 #include "llvm/CodeGen/MachineFrameInfo.h"
21 #include "llvm/CodeGen/MachineFunction.h"
22 #include "llvm/CodeGen/MachineInstrBuilder.h"
23 #include "llvm/CodeGen/SelectionDAG.h"
24 #include "llvm/CodeGen/SelectionDAGISel.h"
25 #include "llvm/CodeGen/SSARegMap.h"
26 #include "llvm/Target/TargetLowering.h"
27 #include "llvm/Support/Debug.h"
33 class ARMTargetLowering : public TargetLowering {
35 ARMTargetLowering(TargetMachine &TM);
36 virtual SDOperand LowerOperation(SDOperand Op, SelectionDAG &DAG);
37 virtual const char *getTargetNodeName(unsigned Opcode) const;
42 ARMTargetLowering::ARMTargetLowering(TargetMachine &TM)
43 : TargetLowering(TM) {
44 setOperationAction(ISD::RET, MVT::Other, Custom);
50 // Start the numbering where the builting ops and target ops leave off.
51 FIRST_NUMBER = ISD::BUILTIN_OP_END+ARM::INSTRUCTION_LIST_END,
52 /// CALL - A direct function call.
58 const char *ARMTargetLowering::getTargetNodeName(unsigned Opcode) const {
61 case ARMISD::CALL: return "ARMISD::CALL";
65 // This transforms a ISD::CALL node into a
66 // callseq_star <- ARMISD:CALL <- callseq_end
68 static SDOperand LowerCALL(SDOperand Op, SelectionDAG &DAG) {
69 SDOperand Chain = Op.getOperand(0);
70 unsigned CallConv = cast<ConstantSDNode>(Op.getOperand(1))->getValue();
71 assert(CallConv == CallingConv::C && "unknown calling convention");
72 bool isVarArg = cast<ConstantSDNode>(Op.getOperand(2))->getValue() != 0;
73 assert(isVarArg == false && "VarArg not supported");
74 bool isTailCall = cast<ConstantSDNode>(Op.getOperand(3))->getValue() != 0;
75 assert(isTailCall == false && "tail call not supported");
76 SDOperand Callee = Op.getOperand(4);
77 unsigned NumOps = (Op.getNumOperands() - 5) / 2;
79 // Count how many bytes are to be pushed on the stack. Initially
80 // only the link register.
81 unsigned NumBytes = 4;
83 assert(NumOps <= 4); //no args on the stack
85 // Adjust the stack pointer for the new arguments...
86 // These operations are automatically eliminated by the prolog/epilog pass
87 Chain = DAG.getCALLSEQ_START(Chain,
88 DAG.getConstant(NumBytes, MVT::i32));
90 static const unsigned regs[] = {
91 ARM::R0, ARM::R1, ARM::R2, ARM::R3
94 std::vector<std::pair<unsigned, SDOperand> > RegsToPass;
96 for (unsigned i = 0; i != NumOps; ++i) {
97 SDOperand Arg = Op.getOperand(5+2*i);
98 RegsToPass.push_back(std::make_pair(regs[i], Arg));
101 // Build a sequence of copy-to-reg nodes chained together with token chain
102 // and flag operands which copy the outgoing args into the appropriate regs.
104 for (unsigned i = 0, e = RegsToPass.size(); i != e; ++i) {
105 Chain = DAG.getCopyToReg(Chain, RegsToPass[i].first, RegsToPass[i].second,
107 InFlag = Chain.getValue(1);
110 std::vector<MVT::ValueType> NodeTys;
111 NodeTys.push_back(MVT::Other); // Returns a chain
112 NodeTys.push_back(MVT::Flag); // Returns a flag for retval copy to use.
114 // If the callee is a GlobalAddress/ExternalSymbol node (quite common, every
115 // direct call is) turn it into a TargetGlobalAddress/TargetExternalSymbol
116 // node so that legalize doesn't hack it.
117 if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee))
118 Callee = DAG.getTargetGlobalAddress(G->getGlobal(), Callee.getValueType());
120 // If this is a direct call, pass the chain and the callee.
122 std::vector<SDOperand> Ops;
123 Ops.push_back(Chain);
124 Ops.push_back(Callee);
126 unsigned CallOpc = ARMISD::CALL;
128 Ops.push_back(InFlag);
129 Chain = DAG.getNode(CallOpc, NodeTys, Ops);
130 InFlag = Chain.getValue(1);
132 std::vector<SDOperand> ResultVals;
135 // If the call has results, copy the values out of the ret val registers.
136 switch (Op.Val->getValueType(0)) {
137 default: assert(0 && "Unexpected ret value!");
141 Chain = DAG.getCopyFromReg(Chain, ARM::R0, MVT::i32, InFlag).getValue(1);
142 ResultVals.push_back(Chain.getValue(0));
143 NodeTys.push_back(MVT::i32);
146 Chain = DAG.getNode(ISD::CALLSEQ_END, MVT::Other, Chain,
147 DAG.getConstant(NumBytes, MVT::i32));
148 NodeTys.push_back(MVT::Other);
150 if (ResultVals.empty())
153 ResultVals.push_back(Chain);
154 SDOperand Res = DAG.getNode(ISD::MERGE_VALUES, NodeTys, ResultVals);
155 return Res.getValue(Op.ResNo);
158 static SDOperand LowerRET(SDOperand Op, SelectionDAG &DAG) {
160 SDOperand Chain = Op.getOperand(0);
161 switch(Op.getNumOperands()) {
163 assert(0 && "Do not know how to return this many arguments!");
166 SDOperand LR = DAG.getRegister(ARM::R14, MVT::i32);
167 return DAG.getNode(ISD::BRIND, MVT::Other, Chain, LR);
170 Copy = DAG.getCopyToReg(Chain, ARM::R0, Op.getOperand(1), SDOperand());
171 if (DAG.getMachineFunction().liveout_empty())
172 DAG.getMachineFunction().addLiveOut(ARM::R0);
176 SDOperand LR = DAG.getRegister(ARM::R14, MVT::i32);
178 //bug: the copy and branch should be linked with a flag so that the
179 //scheduller can't move an instruction that destroys R0 in between them
180 //return DAG.getNode(ISD::BRIND, MVT::Other, Copy, LR, Copy.getValue(1));
182 return DAG.getNode(ISD::BRIND, MVT::Other, Copy, LR);
185 static SDOperand LowerFORMAL_ARGUMENT(SDOperand Op, SelectionDAG &DAG,
187 MachineFunction &MF = DAG.getMachineFunction();
188 MVT::ValueType ObjectVT = Op.getValue(ArgNo).getValueType();
189 assert (ObjectVT == MVT::i32);
190 SDOperand Root = Op.getOperand(0);
191 SSARegMap *RegMap = MF.getSSARegMap();
193 unsigned num_regs = 4;
194 static const unsigned REGS[] = {
195 ARM::R0, ARM::R1, ARM::R2, ARM::R3
198 if(ArgNo < num_regs) {
199 unsigned VReg = RegMap->createVirtualRegister(&ARM::IntRegsRegClass);
200 MF.addLiveIn(REGS[ArgNo], VReg);
201 return DAG.getCopyFromReg(Root, VReg, MVT::i32);
203 // If the argument is actually used, emit a load from the right stack
205 if (!Op.Val->hasNUsesOfValue(0, ArgNo)) {
206 unsigned ArgOffset = (ArgNo - num_regs) * 4;
208 MachineFrameInfo *MFI = MF.getFrameInfo();
209 unsigned ObjSize = MVT::getSizeInBits(ObjectVT)/8;
210 int FI = MFI->CreateFixedObject(ObjSize, ArgOffset);
211 SDOperand FIN = DAG.getFrameIndex(FI, MVT::i32);
212 return DAG.getLoad(ObjectVT, Root, FIN,
213 DAG.getSrcValue(NULL));
215 // Don't emit a dead load.
216 return DAG.getNode(ISD::UNDEF, ObjectVT);
221 static SDOperand LowerFORMAL_ARGUMENTS(SDOperand Op, SelectionDAG &DAG) {
222 std::vector<SDOperand> ArgValues;
223 SDOperand Root = Op.getOperand(0);
225 for (unsigned ArgNo = 0, e = Op.Val->getNumValues()-1; ArgNo != e; ++ArgNo) {
226 SDOperand ArgVal = LowerFORMAL_ARGUMENT(Op, DAG, ArgNo);
228 ArgValues.push_back(ArgVal);
231 bool isVarArg = cast<ConstantSDNode>(Op.getOperand(2))->getValue() != 0;
234 ArgValues.push_back(Root);
236 // Return the new list of results.
237 std::vector<MVT::ValueType> RetVT(Op.Val->value_begin(),
238 Op.Val->value_end());
239 return DAG.getNode(ISD::MERGE_VALUES, RetVT, ArgValues);
242 SDOperand ARMTargetLowering::LowerOperation(SDOperand Op, SelectionDAG &DAG) {
243 switch (Op.getOpcode()) {
245 assert(0 && "Should not custom lower this!");
247 case ISD::FORMAL_ARGUMENTS:
248 return LowerFORMAL_ARGUMENTS(Op, DAG);
250 return LowerCALL(Op, DAG);
252 return LowerRET(Op, DAG);
256 //===----------------------------------------------------------------------===//
257 // Instruction Selector Implementation
258 //===----------------------------------------------------------------------===//
260 //===--------------------------------------------------------------------===//
261 /// ARMDAGToDAGISel - ARM specific code to select ARM machine
262 /// instructions for SelectionDAG operations.
265 class ARMDAGToDAGISel : public SelectionDAGISel {
266 ARMTargetLowering Lowering;
269 ARMDAGToDAGISel(TargetMachine &TM)
270 : SelectionDAGISel(Lowering), Lowering(TM) {
273 void Select(SDOperand &Result, SDOperand Op);
274 virtual void InstructionSelectBasicBlock(SelectionDAG &DAG);
275 bool SelectAddrRegImm(SDOperand N, SDOperand &Offset, SDOperand &Base);
277 // Include the pieces autogenerated from the target description.
278 #include "ARMGenDAGISel.inc"
281 void ARMDAGToDAGISel::InstructionSelectBasicBlock(SelectionDAG &DAG) {
284 DAG.setRoot(SelectRoot(DAG.getRoot()));
285 assert(InFlightSet.empty() && "ISel InFlightSet has not been emptied!");
289 DAG.RemoveDeadNodes();
291 ScheduleAndEmitDAG(DAG);
294 //register plus/minus 12 bit offset
295 bool ARMDAGToDAGISel::SelectAddrRegImm(SDOperand N, SDOperand &Offset,
297 Offset = CurDAG->getTargetConstant(0, MVT::i32);
298 if (FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(N)) {
299 Base = CurDAG->getTargetFrameIndex(FI->getIndex(), N.getValueType());
303 return true; //any address fits in a register
306 void ARMDAGToDAGISel::Select(SDOperand &Result, SDOperand Op) {
309 switch (N->getOpcode()) {
311 SelectCode(Result, Op);
316 } // end anonymous namespace
318 /// createARMISelDag - This pass converts a legalized DAG into a
319 /// ARM-specific DAG, ready for instruction scheduling.
321 FunctionPass *llvm::createARMISelDag(TargetMachine &TM) {
322 return new ARMDAGToDAGISel(TM);