1 //===-- Mips16ISelDAGToDAG.cpp - A Dag to Dag Inst Selector for Mips16 ----===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // Subclass of MipsDAGToDAGISel specialized for mips16.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "Mips16ISelDAGToDAG.h"
14 #include "MCTargetDesc/MipsBaseInfo.h"
15 #include "Mips.h"
16 #include "MipsMachineFunction.h"
17 #include "MipsRegisterInfo.h"
18 #include "llvm/CodeGen/MachineConstantPool.h"
19 #include "llvm/CodeGen/MachineFrameInfo.h"
20 #include "llvm/CodeGen/MachineFunction.h"
21 #include "llvm/CodeGen/MachineInstrBuilder.h"
22 #include "llvm/CodeGen/MachineRegisterInfo.h"
23 #include "llvm/CodeGen/SelectionDAGNodes.h"
24 #include "llvm/IR/CFG.h"
25 #include "llvm/IR/GlobalValue.h"
26 #include "llvm/IR/Instructions.h"
27 #include "llvm/IR/Intrinsics.h"
28 #include "llvm/IR/Type.h"
29 #include "llvm/Support/Debug.h"
30 #include "llvm/Support/ErrorHandling.h"
31 #include "llvm/Support/raw_ostream.h"
32 #include "llvm/Target/TargetMachine.h"
33 using namespace llvm;
34
35 #define DEBUG_TYPE "mips-isel"
36
runOnMachineFunction(MachineFunction & MF)37 bool Mips16DAGToDAGISel::runOnMachineFunction(MachineFunction &MF) {
38 Subtarget = &MF.getSubtarget<MipsSubtarget>();
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,const SDLoc & DL,EVT Ty,bool HasLo,bool HasHi)45 Mips16DAGToDAGISel::selectMULT(SDNode *N, unsigned Opc, const SDLoc &DL, EVT Ty,
46 bool HasLo, bool HasHi) {
47 SDNode *Lo = nullptr, *Hi = nullptr;
48 SDNode *Mul = CurDAG->getMachineNode(Opc, DL, MVT::Glue, N->getOperand(0),
49 N->getOperand(1));
50 SDValue InGlue = SDValue(Mul, 0);
51
52 if (HasLo) {
53 unsigned Opcode = Mips::Mflo16;
54 Lo = CurDAG->getMachineNode(Opcode, DL, Ty, MVT::Glue, InGlue);
55 InGlue = SDValue(Lo, 1);
56 }
57 if (HasHi) {
58 unsigned Opcode = Mips::Mfhi16;
59 Hi = CurDAG->getMachineNode(Opcode, DL, Ty, InGlue);
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 = *Subtarget->getInstrInfo();
74 DebugLoc DL;
75 Register V0, V1, V2, GlobalBaseReg = MipsFI->getGlobalBaseReg(MF);
76 const TargetRegisterClass *RC = &Mips::CPU16RegsRegClass;
77
78 V0 = RegInfo.createVirtualRegister(RC);
79 V1 = RegInfo.createVirtualRegister(RC);
80 V2 = RegInfo.createVirtualRegister(RC);
81
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
88 BuildMI(MBB, I, DL, TII.get(Mips::SllX16), V2).addReg(V0).addImm(16);
89 BuildMI(MBB, I, DL, TII.get(Mips::AdduRxRyRz16), GlobalBaseReg)
90 .addReg(V1)
91 .addReg(V2);
92 }
93
processFunctionAfterISel(MachineFunction & MF)94 void Mips16DAGToDAGISel::processFunctionAfterISel(MachineFunction &MF) {
95 initGlobalBaseReg(MF);
96 }
97
selectAddr(bool SPAllowed,SDValue Addr,SDValue & Base,SDValue & Offset)98 bool Mips16DAGToDAGISel::selectAddr(bool SPAllowed, SDValue Addr, SDValue &Base,
99 SDValue &Offset) {
100 SDLoc DL(Addr);
101 EVT ValTy = Addr.getValueType();
102
103 // if Address is FI, get the TargetFrameIndex.
104 if (SPAllowed) {
105 if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>(Addr)) {
106 Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), ValTy);
107 Offset = CurDAG->getTargetConstant(0, DL, ValTy);
108 return true;
109 }
110 }
111 // on PIC code Load GA
112 if (Addr.getOpcode() == MipsISD::Wrapper) {
113 Base = Addr.getOperand(0);
114 Offset = Addr.getOperand(1);
115 return true;
116 }
117 if (!TM.isPositionIndependent()) {
118 if ((Addr.getOpcode() == ISD::TargetExternalSymbol ||
119 Addr.getOpcode() == ISD::TargetGlobalAddress))
120 return false;
121 }
122 // Addresses of the form FI+const or FI|const
123 if (CurDAG->isBaseWithConstantOffset(Addr)) {
124 auto *CN = cast<ConstantSDNode>(Addr.getOperand(1));
125 if (isInt<16>(CN->getSExtValue())) {
126 // If the first operand is a FI, get the TargetFI Node
127 if (SPAllowed) {
128 if (FrameIndexSDNode *FIN =
129 dyn_cast<FrameIndexSDNode>(Addr.getOperand(0))) {
130 Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), ValTy);
131 Offset = CurDAG->getTargetConstant(CN->getZExtValue(), DL, ValTy);
132 return true;
133 }
134 }
135
136 Base = Addr.getOperand(0);
137 Offset = CurDAG->getTargetConstant(CN->getZExtValue(), DL, ValTy);
138 return true;
139 }
140 }
141 // Operand is a result from an ADD.
142 if (Addr.getOpcode() == ISD::ADD) {
143 // When loading from constant pools, load the lower address part in
144 // the instruction itself. Example, instead of:
145 // lui $2, %hi($CPI1_0)
146 // addiu $2, $2, %lo($CPI1_0)
147 // lwc1 $f0, 0($2)
148 // Generate:
149 // lui $2, %hi($CPI1_0)
150 // lwc1 $f0, %lo($CPI1_0)($2)
151 if (Addr.getOperand(1).getOpcode() == MipsISD::Lo ||
152 Addr.getOperand(1).getOpcode() == MipsISD::GPRel) {
153 SDValue Opnd0 = Addr.getOperand(1).getOperand(0);
154 if (isa<ConstantPoolSDNode>(Opnd0) || isa<GlobalAddressSDNode>(Opnd0) ||
155 isa<JumpTableSDNode>(Opnd0)) {
156 Base = Addr.getOperand(0);
157 Offset = Opnd0;
158 return true;
159 }
160 }
161 }
162 Base = Addr;
163 Offset = CurDAG->getTargetConstant(0, DL, ValTy);
164 return true;
165 }
166
selectAddr16(SDValue Addr,SDValue & Base,SDValue & Offset)167 bool Mips16DAGToDAGISel::selectAddr16(SDValue Addr, SDValue &Base,
168 SDValue &Offset) {
169 return selectAddr(false, Addr, Base, Offset);
170 }
171
selectAddr16SP(SDValue Addr,SDValue & Base,SDValue & Offset)172 bool Mips16DAGToDAGISel::selectAddr16SP(SDValue Addr, SDValue &Base,
173 SDValue &Offset) {
174 return selectAddr(true, Addr, Base, Offset);
175 }
176
177 /// Select instructions not customized! Used for
178 /// expanded, promoted and normal instructions
trySelect(SDNode * Node)179 bool Mips16DAGToDAGISel::trySelect(SDNode *Node) {
180 unsigned Opcode = Node->getOpcode();
181 SDLoc DL(Node);
182
183 ///
184 // Instruction Selection not handled by the auto-generated
185 // tablegen selection should be handled here.
186 ///
187 EVT NodeTy = Node->getValueType(0);
188 unsigned MultOpc;
189
190 switch (Opcode) {
191 default:
192 break;
193
194 /// Mul with two results
195 case ISD::SMUL_LOHI:
196 case ISD::UMUL_LOHI: {
197 MultOpc = (Opcode == ISD::UMUL_LOHI ? Mips::MultuRxRy16 : Mips::MultRxRy16);
198 std::pair<SDNode *, SDNode *> LoHi =
199 selectMULT(Node, MultOpc, DL, NodeTy, true, true);
200 if (!SDValue(Node, 0).use_empty())
201 ReplaceUses(SDValue(Node, 0), SDValue(LoHi.first, 0));
202
203 if (!SDValue(Node, 1).use_empty())
204 ReplaceUses(SDValue(Node, 1), SDValue(LoHi.second, 0));
205
206 CurDAG->RemoveDeadNode(Node);
207 return true;
208 }
209
210 case ISD::MULHS:
211 case ISD::MULHU: {
212 MultOpc = (Opcode == ISD::MULHU ? Mips::MultuRxRy16 : Mips::MultRxRy16);
213 auto LoHi = selectMULT(Node, MultOpc, DL, NodeTy, false, true);
214 ReplaceNode(Node, LoHi.second);
215 return true;
216 }
217 }
218
219 return false;
220 }
221
Mips16DAGToDAGISelLegacy(MipsTargetMachine & TM,CodeGenOptLevel OL)222 Mips16DAGToDAGISelLegacy::Mips16DAGToDAGISelLegacy(MipsTargetMachine &TM,
223 CodeGenOptLevel OL)
224 : MipsDAGToDAGISelLegacy(std::make_unique<Mips16DAGToDAGISel>(TM, OL)) {}
225
createMips16ISelDag(MipsTargetMachine & TM,CodeGenOptLevel OptLevel)226 FunctionPass *llvm::createMips16ISelDag(MipsTargetMachine &TM,
227 CodeGenOptLevel OptLevel) {
228 return new Mips16DAGToDAGISelLegacy(TM, OptLevel);
229 }
230