1 //===- ARCRegisterInfo.cpp - ARC Register Information -----------*- C++ -*-===//
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 // This file contains the ARC implementation of the MRegisterInfo class.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "ARCRegisterInfo.h"
14 #include "ARC.h"
15 #include "ARCInstrInfo.h"
16 #include "ARCMachineFunctionInfo.h"
17 #include "ARCSubtarget.h"
18 #include "llvm/ADT/BitVector.h"
19 #include "llvm/CodeGen/MachineFrameInfo.h"
20 #include "llvm/CodeGen/MachineFunction.h"
21 #include "llvm/CodeGen/MachineInstrBuilder.h"
22 #include "llvm/CodeGen/MachineModuleInfo.h"
23 #include "llvm/CodeGen/MachineRegisterInfo.h"
24 #include "llvm/CodeGen/RegisterScavenging.h"
25 #include "llvm/CodeGen/TargetFrameLowering.h"
26 #include "llvm/IR/Function.h"
27 #include "llvm/Support/Debug.h"
28 #include "llvm/Target/TargetMachine.h"
29 #include "llvm/Target/TargetOptions.h"
30 
31 using namespace llvm;
32 
33 #define DEBUG_TYPE "arc-reg-info"
34 
35 #define GET_REGINFO_TARGET_DESC
36 #include "ARCGenRegisterInfo.inc"
37 
38 static void replaceFrameIndex(MachineBasicBlock::iterator II,
39                               const ARCInstrInfo &TII, unsigned Reg,
40                               unsigned FrameReg, int Offset, int StackSize,
41                               int ObjSize, RegScavenger *RS, int SPAdj) {
42   assert(RS && "Need register scavenger.");
43   MachineInstr &MI = *II;
44   MachineBasicBlock &MBB = *MI.getParent();
45   DebugLoc DL = MI.getDebugLoc();
46   unsigned BaseReg = FrameReg;
47   unsigned KillState = 0;
48   if (MI.getOpcode() == ARC::LD_rs9 && (Offset >= 256 || Offset < -256)) {
49     // Loads can always be reached with LD_rlimm.
50     BuildMI(MBB, II, DL, TII.get(ARC::LD_rlimm), Reg)
51         .addReg(BaseReg)
52         .addImm(Offset)
53         .addMemOperand(*MI.memoperands_begin());
54     MBB.erase(II);
55     return;
56   }
57 
58   if (MI.getOpcode() != ARC::GETFI && (Offset >= 256 || Offset < -256)) {
59     // We need to use a scratch register to reach the far-away frame indexes.
60     BaseReg = RS->FindUnusedReg(&ARC::GPR32RegClass);
61     if (!BaseReg) {
62       // We can be sure that the scavenged-register slot is within the range
63       // of the load offset.
64       const TargetRegisterInfo *TRI =
65           MBB.getParent()->getSubtarget().getRegisterInfo();
66       BaseReg = RS->scavengeRegister(&ARC::GPR32RegClass, II, SPAdj);
67       assert(BaseReg && "Register scavenging failed.");
68       LLVM_DEBUG(dbgs() << "Scavenged register " << printReg(BaseReg, TRI)
69                         << " for FrameReg=" << printReg(FrameReg, TRI)
70                         << "+Offset=" << Offset << "\n");
71       (void)TRI;
72       RS->setRegUsed(BaseReg);
73     }
74     unsigned AddOpc = isUInt<6>(Offset) ? ARC::ADD_rru6 : ARC::ADD_rrlimm;
75     BuildMI(MBB, II, DL, TII.get(AddOpc))
76         .addReg(BaseReg, RegState::Define)
77         .addReg(FrameReg)
78         .addImm(Offset);
79     Offset = 0;
80     KillState = RegState::Kill;
81   }
82   switch (MI.getOpcode()) {
83   case ARC::LD_rs9:
84     assert((Offset % 4 == 0) && "LD needs 4 byte alignment.");
85     [[fallthrough]];
86   case ARC::LDH_rs9:
87   case ARC::LDH_X_rs9:
88     assert((Offset % 2 == 0) && "LDH needs 2 byte alignment.");
89     [[fallthrough]];
90   case ARC::LDB_rs9:
91   case ARC::LDB_X_rs9:
92     LLVM_DEBUG(dbgs() << "Building LDFI\n");
93     BuildMI(MBB, II, DL, TII.get(MI.getOpcode()), Reg)
94         .addReg(BaseReg, KillState)
95         .addImm(Offset)
96         .addMemOperand(*MI.memoperands_begin());
97     break;
98   case ARC::ST_rs9:
99     assert((Offset % 4 == 0) && "ST needs 4 byte alignment.");
100     [[fallthrough]];
101   case ARC::STH_rs9:
102     assert((Offset % 2 == 0) && "STH needs 2 byte alignment.");
103     [[fallthrough]];
104   case ARC::STB_rs9:
105     LLVM_DEBUG(dbgs() << "Building STFI\n");
106     BuildMI(MBB, II, DL, TII.get(MI.getOpcode()))
107         .addReg(Reg, getKillRegState(MI.getOperand(0).isKill()))
108         .addReg(BaseReg, KillState)
109         .addImm(Offset)
110         .addMemOperand(*MI.memoperands_begin());
111     break;
112   case ARC::GETFI:
113     LLVM_DEBUG(dbgs() << "Building GETFI\n");
114     BuildMI(MBB, II, DL,
115             TII.get(isUInt<6>(Offset) ? ARC::ADD_rru6 : ARC::ADD_rrlimm))
116         .addReg(Reg, RegState::Define)
117         .addReg(FrameReg)
118         .addImm(Offset);
119     break;
120   default:
121     llvm_unreachable("Unhandled opcode.");
122   }
123 
124   // Erase old instruction.
125   MBB.erase(II);
126 }
127 
128 ARCRegisterInfo::ARCRegisterInfo(const ARCSubtarget &ST)
129     : ARCGenRegisterInfo(ARC::BLINK), ST(ST) {}
130 
131 bool ARCRegisterInfo::needsFrameMoves(const MachineFunction &MF) {
132   return MF.needsFrameMoves();
133 }
134 
135 const MCPhysReg *
136 ARCRegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
137   return CSR_ARC_SaveList;
138 }
139 
140 BitVector ARCRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
141   BitVector Reserved(getNumRegs());
142 
143   Reserved.set(ARC::ILINK);
144   Reserved.set(ARC::SP);
145   Reserved.set(ARC::GP);
146   Reserved.set(ARC::R25);
147   Reserved.set(ARC::BLINK);
148   Reserved.set(ARC::FP);
149 
150   return Reserved;
151 }
152 
153 bool ARCRegisterInfo::requiresRegisterScavenging(
154     const MachineFunction &MF) const {
155   return true;
156 }
157 
158 bool ARCRegisterInfo::useFPForScavengingIndex(const MachineFunction &MF) const {
159   return true;
160 }
161 
162 bool ARCRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
163                                           int SPAdj, unsigned FIOperandNum,
164                                           RegScavenger *RS) const {
165   assert(SPAdj == 0 && "Unexpected");
166   MachineInstr &MI = *II;
167   MachineOperand &FrameOp = MI.getOperand(FIOperandNum);
168   int FrameIndex = FrameOp.getIndex();
169 
170   MachineFunction &MF = *MI.getParent()->getParent();
171   const ARCInstrInfo &TII = *MF.getSubtarget<ARCSubtarget>().getInstrInfo();
172   const ARCFrameLowering *TFI = getFrameLowering(MF);
173   int Offset = MF.getFrameInfo().getObjectOffset(FrameIndex);
174   int ObjSize = MF.getFrameInfo().getObjectSize(FrameIndex);
175   int StackSize = MF.getFrameInfo().getStackSize();
176   int LocalFrameSize = MF.getFrameInfo().getLocalFrameSize();
177 
178   LLVM_DEBUG(dbgs() << "\nFunction         : " << MF.getName() << "\n");
179   LLVM_DEBUG(dbgs() << "<--------->\n");
180   LLVM_DEBUG(dbgs() << MI << "\n");
181   LLVM_DEBUG(dbgs() << "FrameIndex         : " << FrameIndex << "\n");
182   LLVM_DEBUG(dbgs() << "ObjSize            : " << ObjSize << "\n");
183   LLVM_DEBUG(dbgs() << "FrameOffset        : " << Offset << "\n");
184   LLVM_DEBUG(dbgs() << "StackSize          : " << StackSize << "\n");
185   LLVM_DEBUG(dbgs() << "LocalFrameSize     : " << LocalFrameSize << "\n");
186   (void)LocalFrameSize;
187 
188   // Special handling of DBG_VALUE instructions.
189   if (MI.isDebugValue()) {
190     Register FrameReg = getFrameRegister(MF);
191     MI.getOperand(FIOperandNum).ChangeToRegister(FrameReg, false /*isDef*/);
192     MI.getOperand(FIOperandNum + 1).ChangeToImmediate(Offset);
193     return false;
194   }
195 
196   // fold constant into offset.
197   Offset += MI.getOperand(FIOperandNum + 1).getImm();
198 
199   // TODO: assert based on the load type:
200   // ldb needs no alignment,
201   // ldh needs 2 byte alignment
202   // ld needs 4 byte alignment
203   LLVM_DEBUG(dbgs() << "Offset             : " << Offset << "\n"
204                     << "<--------->\n");
205 
206   Register Reg = MI.getOperand(0).getReg();
207   assert(ARC::GPR32RegClass.contains(Reg) && "Unexpected register operand");
208 
209   if (!TFI->hasFP(MF)) {
210     Offset = StackSize + Offset;
211     if (FrameIndex >= 0)
212       assert((Offset >= 0 && Offset < StackSize) && "SP Offset not in bounds.");
213   } else {
214     if (FrameIndex >= 0) {
215       assert((Offset < 0 && -Offset <= StackSize) &&
216              "FP Offset not in bounds.");
217     }
218   }
219   replaceFrameIndex(II, TII, Reg, getFrameRegister(MF), Offset, StackSize,
220                     ObjSize, RS, SPAdj);
221   return true;
222 }
223 
224 Register ARCRegisterInfo::getFrameRegister(const MachineFunction &MF) const {
225   const ARCFrameLowering *TFI = getFrameLowering(MF);
226   return TFI->hasFP(MF) ? ARC::FP : ARC::SP;
227 }
228 
229 const uint32_t *
230 ARCRegisterInfo::getCallPreservedMask(const MachineFunction &MF,
231                                       CallingConv::ID CC) const {
232   return CSR_ARC_RegMask;
233 }
234