1 //===-- Mips16ISelDAGToDAG.cpp - A Dag to Dag Inst Selector for Mips16 ----===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // Subclass of MipsDAGToDAGISel specialized for mips16.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #define DEBUG_TYPE "mips-isel"
15 #include "Mips16ISelDAGToDAG.h"
16 #include "Mips.h"
17 #include "MCTargetDesc/MipsBaseInfo.h"
18 #include "MipsAnalyzeImmediate.h"
19 #include "MipsMachineFunction.h"
20 #include "MipsRegisterInfo.h"
21 #include "llvm/CodeGen/MachineConstantPool.h"
22 #include "llvm/CodeGen/MachineFrameInfo.h"
23 #include "llvm/CodeGen/MachineFunction.h"
24 #include "llvm/CodeGen/MachineInstrBuilder.h"
25 #include "llvm/CodeGen/MachineRegisterInfo.h"
26 #include "llvm/CodeGen/SelectionDAGNodes.h"
27 #include "llvm/IR/GlobalValue.h"
28 #include "llvm/IR/Instructions.h"
29 #include "llvm/IR/Intrinsics.h"
30 #include "llvm/IR/Type.h"
31 #include "llvm/Support/CFG.h"
32 #include "llvm/Support/Debug.h"
33 #include "llvm/Support/ErrorHandling.h"
34 #include "llvm/Support/raw_ostream.h"
35 #include "llvm/Target/TargetMachine.h"
36 using namespace llvm;
37
runOnMachineFunction(MachineFunction & MF)38 bool Mips16DAGToDAGISel::runOnMachineFunction(MachineFunction &MF) {
39 if (!Subtarget.inMips16Mode())
40 return false;
41 return MipsDAGToDAGISel::runOnMachineFunction(MF);
42 }
43 /// Select multiply instructions.
44 std::pair<SDNode*, SDNode*>
selectMULT(SDNode * N,unsigned Opc,SDLoc DL,EVT Ty,bool HasLo,bool HasHi)45 Mips16DAGToDAGISel::selectMULT(SDNode *N, unsigned Opc, SDLoc DL, EVT Ty,
46 bool HasLo, bool HasHi) {
47 SDNode *Lo = 0, *Hi = 0;
48 SDNode *Mul = CurDAG->getMachineNode(Opc, DL, MVT::Glue, N->getOperand(0),
49 N->getOperand(1));
50 SDValue InFlag = SDValue(Mul, 0);
51
52 if (HasLo) {
53 unsigned Opcode = Mips::Mflo16;
54 Lo = CurDAG->getMachineNode(Opcode, DL, Ty, MVT::Glue, InFlag);
55 InFlag = SDValue(Lo, 1);
56 }
57 if (HasHi) {
58 unsigned Opcode = Mips::Mfhi16;
59 Hi = CurDAG->getMachineNode(Opcode, DL, Ty, InFlag);
60 }
61 return std::make_pair(Lo, Hi);
62 }
63
initGlobalBaseReg(MachineFunction & MF)64 void Mips16DAGToDAGISel::initGlobalBaseReg(MachineFunction &MF) {
65 MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
66
67 if (!MipsFI->globalBaseRegSet())
68 return;
69
70 MachineBasicBlock &MBB = MF.front();
71 MachineBasicBlock::iterator I = MBB.begin();
72 MachineRegisterInfo &RegInfo = MF.getRegInfo();
73 const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
74 DebugLoc DL = I != MBB.end() ? I->getDebugLoc() : DebugLoc();
75 unsigned V0, V1, V2, GlobalBaseReg = MipsFI->getGlobalBaseReg();
76 const TargetRegisterClass *RC =
77 (const TargetRegisterClass*)&Mips::CPU16RegsRegClass;
78
79 V0 = RegInfo.createVirtualRegister(RC);
80 V1 = RegInfo.createVirtualRegister(RC);
81 V2 = RegInfo.createVirtualRegister(RC);
82
83 BuildMI(MBB, I, DL, TII.get(Mips::LiRxImmX16), V0)
84 .addExternalSymbol("_gp_disp", MipsII::MO_ABS_HI);
85 BuildMI(MBB, I, DL, TII.get(Mips::AddiuRxPcImmX16), V1)
86 .addExternalSymbol("_gp_disp", MipsII::MO_ABS_LO);
87 BuildMI(MBB, I, DL, TII.get(Mips::SllX16), V2).addReg(V0).addImm(16);
88 BuildMI(MBB, I, DL, TII.get(Mips::AdduRxRyRz16), GlobalBaseReg)
89 .addReg(V1).addReg(V2);
90 }
91
92 // Insert instructions to initialize the Mips16 SP Alias register in the
93 // first MBB of the function.
94 //
initMips16SPAliasReg(MachineFunction & MF)95 void Mips16DAGToDAGISel::initMips16SPAliasReg(MachineFunction &MF) {
96 MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
97
98 if (!MipsFI->mips16SPAliasRegSet())
99 return;
100
101 MachineBasicBlock &MBB = MF.front();
102 MachineBasicBlock::iterator I = MBB.begin();
103 const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
104 DebugLoc DL = I != MBB.end() ? I->getDebugLoc() : DebugLoc();
105 unsigned Mips16SPAliasReg = MipsFI->getMips16SPAliasReg();
106
107 BuildMI(MBB, I, DL, TII.get(Mips::MoveR3216), Mips16SPAliasReg)
108 .addReg(Mips::SP);
109 }
110
processFunctionAfterISel(MachineFunction & MF)111 void Mips16DAGToDAGISel::processFunctionAfterISel(MachineFunction &MF) {
112 initGlobalBaseReg(MF);
113 initMips16SPAliasReg(MF);
114 }
115
116 /// getMips16SPAliasReg - Output the instructions required to put the
117 /// SP into a Mips16 accessible aliased register.
getMips16SPAliasReg()118 SDValue Mips16DAGToDAGISel::getMips16SPAliasReg() {
119 unsigned Mips16SPAliasReg =
120 MF->getInfo<MipsFunctionInfo>()->getMips16SPAliasReg();
121 return CurDAG->getRegister(Mips16SPAliasReg,
122 getTargetLowering()->getPointerTy());
123 }
124
getMips16SPRefReg(SDNode * Parent,SDValue & AliasReg)125 void Mips16DAGToDAGISel::getMips16SPRefReg(SDNode *Parent, SDValue &AliasReg) {
126 SDValue AliasFPReg = CurDAG->getRegister(Mips::S0,
127 getTargetLowering()->getPointerTy());
128 if (Parent) {
129 switch (Parent->getOpcode()) {
130 case ISD::LOAD: {
131 LoadSDNode *SD = dyn_cast<LoadSDNode>(Parent);
132 switch (SD->getMemoryVT().getSizeInBits()) {
133 case 8:
134 case 16:
135 AliasReg = TM.getFrameLowering()->hasFP(*MF)?
136 AliasFPReg: getMips16SPAliasReg();
137 return;
138 }
139 break;
140 }
141 case ISD::STORE: {
142 StoreSDNode *SD = dyn_cast<StoreSDNode>(Parent);
143 switch (SD->getMemoryVT().getSizeInBits()) {
144 case 8:
145 case 16:
146 AliasReg = TM.getFrameLowering()->hasFP(*MF)?
147 AliasFPReg: getMips16SPAliasReg();
148 return;
149 }
150 break;
151 }
152 }
153 }
154 AliasReg = CurDAG->getRegister(Mips::SP, getTargetLowering()->getPointerTy());
155 return;
156
157 }
158
selectAddr16(SDNode * Parent,SDValue Addr,SDValue & Base,SDValue & Offset,SDValue & Alias)159 bool Mips16DAGToDAGISel::selectAddr16(
160 SDNode *Parent, SDValue Addr, SDValue &Base, SDValue &Offset,
161 SDValue &Alias) {
162 EVT ValTy = Addr.getValueType();
163
164 Alias = CurDAG->getTargetConstant(0, ValTy);
165
166 // if Address is FI, get the TargetFrameIndex.
167 if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>(Addr)) {
168 Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), ValTy);
169 Offset = CurDAG->getTargetConstant(0, ValTy);
170 getMips16SPRefReg(Parent, Alias);
171 return true;
172 }
173 // on PIC code Load GA
174 if (Addr.getOpcode() == MipsISD::Wrapper) {
175 Base = Addr.getOperand(0);
176 Offset = Addr.getOperand(1);
177 return true;
178 }
179 if (TM.getRelocationModel() != Reloc::PIC_) {
180 if ((Addr.getOpcode() == ISD::TargetExternalSymbol ||
181 Addr.getOpcode() == ISD::TargetGlobalAddress))
182 return false;
183 }
184 // Addresses of the form FI+const or FI|const
185 if (CurDAG->isBaseWithConstantOffset(Addr)) {
186 ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr.getOperand(1));
187 if (isInt<16>(CN->getSExtValue())) {
188
189 // If the first operand is a FI, get the TargetFI Node
190 if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>
191 (Addr.getOperand(0))) {
192 Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), ValTy);
193 getMips16SPRefReg(Parent, Alias);
194 }
195 else
196 Base = Addr.getOperand(0);
197
198 Offset = CurDAG->getTargetConstant(CN->getZExtValue(), ValTy);
199 return true;
200 }
201 }
202 // Operand is a result from an ADD.
203 if (Addr.getOpcode() == ISD::ADD) {
204 // When loading from constant pools, load the lower address part in
205 // the instruction itself. Example, instead of:
206 // lui $2, %hi($CPI1_0)
207 // addiu $2, $2, %lo($CPI1_0)
208 // lwc1 $f0, 0($2)
209 // Generate:
210 // lui $2, %hi($CPI1_0)
211 // lwc1 $f0, %lo($CPI1_0)($2)
212 if (Addr.getOperand(1).getOpcode() == MipsISD::Lo ||
213 Addr.getOperand(1).getOpcode() == MipsISD::GPRel) {
214 SDValue Opnd0 = Addr.getOperand(1).getOperand(0);
215 if (isa<ConstantPoolSDNode>(Opnd0) || isa<GlobalAddressSDNode>(Opnd0) ||
216 isa<JumpTableSDNode>(Opnd0)) {
217 Base = Addr.getOperand(0);
218 Offset = Opnd0;
219 return true;
220 }
221 }
222
223 // If an indexed floating point load/store can be emitted, return false.
224 const LSBaseSDNode *LS = dyn_cast<LSBaseSDNode>(Parent);
225
226 if (LS &&
227 (LS->getMemoryVT() == MVT::f32 || LS->getMemoryVT() == MVT::f64) &&
228 Subtarget.hasFPIdx())
229 return false;
230 }
231 Base = Addr;
232 Offset = CurDAG->getTargetConstant(0, ValTy);
233 return true;
234 }
235
236 /// Select instructions not customized! Used for
237 /// expanded, promoted and normal instructions
selectNode(SDNode * Node)238 std::pair<bool, SDNode*> Mips16DAGToDAGISel::selectNode(SDNode *Node) {
239 unsigned Opcode = Node->getOpcode();
240 SDLoc DL(Node);
241
242 ///
243 // Instruction Selection not handled by the auto-generated
244 // tablegen selection should be handled here.
245 ///
246 EVT NodeTy = Node->getValueType(0);
247 unsigned MultOpc;
248
249 switch(Opcode) {
250 default: break;
251
252 case ISD::SUBE:
253 case ISD::ADDE: {
254 SDValue InFlag = Node->getOperand(2), CmpLHS;
255 unsigned Opc = InFlag.getOpcode(); (void)Opc;
256 assert(((Opc == ISD::ADDC || Opc == ISD::ADDE) ||
257 (Opc == ISD::SUBC || Opc == ISD::SUBE)) &&
258 "(ADD|SUB)E flag operand must come from (ADD|SUB)C/E insn");
259
260 unsigned MOp;
261 if (Opcode == ISD::ADDE) {
262 CmpLHS = InFlag.getValue(0);
263 MOp = Mips::AdduRxRyRz16;
264 } else {
265 CmpLHS = InFlag.getOperand(0);
266 MOp = Mips::SubuRxRyRz16;
267 }
268
269 SDValue Ops[] = { CmpLHS, InFlag.getOperand(1) };
270
271 SDValue LHS = Node->getOperand(0);
272 SDValue RHS = Node->getOperand(1);
273
274 EVT VT = LHS.getValueType();
275
276 unsigned Sltu_op = Mips::SltuRxRyRz16;
277 SDNode *Carry = CurDAG->getMachineNode(Sltu_op, DL, VT, Ops);
278 unsigned Addu_op = Mips::AdduRxRyRz16;
279 SDNode *AddCarry = CurDAG->getMachineNode(Addu_op, DL, VT,
280 SDValue(Carry,0), RHS);
281
282 SDNode *Result = CurDAG->SelectNodeTo(Node, MOp, VT, MVT::Glue, LHS,
283 SDValue(AddCarry,0));
284 return std::make_pair(true, Result);
285 }
286
287 /// Mul with two results
288 case ISD::SMUL_LOHI:
289 case ISD::UMUL_LOHI: {
290 MultOpc = (Opcode == ISD::UMUL_LOHI ? Mips::MultuRxRy16 : Mips::MultRxRy16);
291 std::pair<SDNode*, SDNode*> LoHi = selectMULT(Node, MultOpc, DL, NodeTy,
292 true, true);
293 if (!SDValue(Node, 0).use_empty())
294 ReplaceUses(SDValue(Node, 0), SDValue(LoHi.first, 0));
295
296 if (!SDValue(Node, 1).use_empty())
297 ReplaceUses(SDValue(Node, 1), SDValue(LoHi.second, 0));
298
299 return std::make_pair(true, (SDNode*)NULL);
300 }
301
302 case ISD::MULHS:
303 case ISD::MULHU: {
304 MultOpc = (Opcode == ISD::MULHU ? Mips::MultuRxRy16 : Mips::MultRxRy16);
305 SDNode *Result = selectMULT(Node, MultOpc, DL, NodeTy, false, true).second;
306 return std::make_pair(true, Result);
307 }
308 }
309
310 return std::make_pair(false, (SDNode*)NULL);
311 }
312
createMips16ISelDag(MipsTargetMachine & TM)313 FunctionPass *llvm::createMips16ISelDag(MipsTargetMachine &TM) {
314 return new Mips16DAGToDAGISel(TM);
315 }
316