1 //===-- PPCMCInstLower.cpp - Convert PPC MachineInstr to an MCInst --------===//
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 code to lower PPC MachineInstrs to their corresponding
10 // MCInst records.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "MCTargetDesc/PPCMCExpr.h"
15 #include "PPC.h"
16 #include "PPCSubtarget.h"
17 #include "llvm/ADT/SmallString.h"
18 #include "llvm/ADT/Twine.h"
19 #include "llvm/CodeGen/AsmPrinter.h"
20 #include "llvm/CodeGen/MachineFunction.h"
21 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
22 #include "llvm/CodeGen/TargetLowering.h"
23 #include "llvm/IR/DataLayout.h"
24 #include "llvm/IR/GlobalValue.h"
25 #include "llvm/IR/Mangler.h"
26 #include "llvm/MC/MCAsmInfo.h"
27 #include "llvm/MC/MCExpr.h"
28 #include "llvm/MC/MCInst.h"
29 #include "llvm/Target/TargetLoweringObjectFile.h"
30 using namespace llvm;
31 
32 static MachineModuleInfoMachO &getMachOMMI(AsmPrinter &AP) {
33   return AP.MMI->getObjFileInfo<MachineModuleInfoMachO>();
34 }
35 
36 static MCSymbol *GetSymbolFromOperand(const MachineOperand &MO,
37                                       AsmPrinter &AP) {
38   const TargetMachine &TM = AP.TM;
39   Mangler &Mang = TM.getObjFileLowering()->getMangler();
40   const DataLayout &DL = AP.getDataLayout();
41   MCContext &Ctx = AP.OutContext;
42 
43   SmallString<128> Name;
44   StringRef Suffix;
45   if (MO.getTargetFlags() & PPCII::MO_NLP_FLAG)
46     Suffix = "$non_lazy_ptr";
47 
48   if (!Suffix.empty())
49     Name += DL.getPrivateGlobalPrefix();
50 
51   if (!MO.isGlobal()) {
52     assert(MO.isSymbol() && "Isn't a symbol reference");
53     Mangler::getNameWithPrefix(Name, MO.getSymbolName(), DL);
54   } else {
55     const GlobalValue *GV = MO.getGlobal();
56     TM.getNameWithPrefix(Name, GV, Mang);
57   }
58 
59   Name += Suffix;
60   MCSymbol *Sym = Ctx.getOrCreateSymbol(Name);
61 
62   // If the symbol reference is actually to a non_lazy_ptr, not to the symbol,
63   // then add the suffix.
64   if (MO.getTargetFlags() & PPCII::MO_NLP_FLAG) {
65     MachineModuleInfoMachO &MachO = getMachOMMI(AP);
66 
67     MachineModuleInfoImpl::StubValueTy &StubSym = MachO.getGVStubEntry(Sym);
68 
69     if (!StubSym.getPointer()) {
70       assert(MO.isGlobal() && "Extern symbol not handled yet");
71       StubSym = MachineModuleInfoImpl::
72                    StubValueTy(AP.getSymbol(MO.getGlobal()),
73                                !MO.getGlobal()->hasInternalLinkage());
74     }
75     return Sym;
76   }
77 
78   return Sym;
79 }
80 
81 static MCOperand GetSymbolRef(const MachineOperand &MO, const MCSymbol *Symbol,
82                               AsmPrinter &Printer, bool IsDarwin) {
83   MCContext &Ctx = Printer.OutContext;
84   MCSymbolRefExpr::VariantKind RefKind = MCSymbolRefExpr::VK_None;
85 
86   unsigned access = MO.getTargetFlags() & PPCII::MO_ACCESS_MASK;
87 
88   switch (access) {
89     case PPCII::MO_TPREL_LO:
90       RefKind = MCSymbolRefExpr::VK_PPC_TPREL_LO;
91       break;
92     case PPCII::MO_TPREL_HA:
93       RefKind = MCSymbolRefExpr::VK_PPC_TPREL_HA;
94       break;
95     case PPCII::MO_DTPREL_LO:
96       RefKind = MCSymbolRefExpr::VK_PPC_DTPREL_LO;
97       break;
98     case PPCII::MO_TLSLD_LO:
99       RefKind = MCSymbolRefExpr::VK_PPC_GOT_TLSLD_LO;
100       break;
101     case PPCII::MO_TOC_LO:
102       RefKind = MCSymbolRefExpr::VK_PPC_TOC_LO;
103       break;
104     case PPCII::MO_TLS:
105       RefKind = MCSymbolRefExpr::VK_PPC_TLS;
106       break;
107   }
108 
109  if (MO.getTargetFlags() == PPCII::MO_PLT)
110     RefKind = MCSymbolRefExpr::VK_PLT;
111 
112   const MachineFunction *MF = MO.getParent()->getParent()->getParent();
113   const Module *M = MF->getFunction().getParent();
114   const PPCSubtarget *Subtarget = &(MF->getSubtarget<PPCSubtarget>());
115   const TargetMachine &TM = Printer.TM;
116   const MCExpr *Expr = MCSymbolRefExpr::create(Symbol, RefKind, Ctx);
117   // If -msecure-plt -fPIC, add 32768 to symbol.
118   if (Subtarget->isSecurePlt() && TM.isPositionIndependent() &&
119       M->getPICLevel() == PICLevel::BigPIC &&
120       MO.getTargetFlags() == PPCII::MO_PLT)
121     Expr =
122         MCBinaryExpr::createAdd(Expr, MCConstantExpr::create(32768, Ctx), Ctx);
123 
124   if (!MO.isJTI() && MO.getOffset())
125     Expr = MCBinaryExpr::createAdd(Expr,
126                                    MCConstantExpr::create(MO.getOffset(), Ctx),
127                                    Ctx);
128 
129   // Subtract off the PIC base if required.
130   if (MO.getTargetFlags() & PPCII::MO_PIC_FLAG) {
131     const MachineFunction *MF = MO.getParent()->getParent()->getParent();
132 
133     const MCExpr *PB = MCSymbolRefExpr::create(MF->getPICBaseSymbol(), Ctx);
134     Expr = MCBinaryExpr::createSub(Expr, PB, Ctx);
135   }
136 
137   // Add ha16() / lo16() markers if required.
138   switch (access) {
139     case PPCII::MO_LO:
140       Expr = PPCMCExpr::createLo(Expr, IsDarwin, Ctx);
141       break;
142     case PPCII::MO_HA:
143       Expr = PPCMCExpr::createHa(Expr, IsDarwin, Ctx);
144       break;
145   }
146 
147   return MCOperand::createExpr(Expr);
148 }
149 
150 void llvm::LowerPPCMachineInstrToMCInst(const MachineInstr *MI, MCInst &OutMI,
151                                         AsmPrinter &AP, bool IsDarwin) {
152   OutMI.setOpcode(MI->getOpcode());
153 
154   for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
155     MCOperand MCOp;
156     if (LowerPPCMachineOperandToMCOperand(MI->getOperand(i), MCOp, AP,
157                                           IsDarwin))
158       OutMI.addOperand(MCOp);
159   }
160 }
161 
162 bool llvm::LowerPPCMachineOperandToMCOperand(const MachineOperand &MO,
163                                              MCOperand &OutMO, AsmPrinter &AP,
164                                              bool IsDarwin) {
165   switch (MO.getType()) {
166   default:
167     llvm_unreachable("unknown operand type");
168   case MachineOperand::MO_Register:
169     assert(!MO.getSubReg() && "Subregs should be eliminated!");
170     assert(MO.getReg() > PPC::NoRegister &&
171            MO.getReg() < PPC::NUM_TARGET_REGS &&
172            "Invalid register for this target!");
173     OutMO = MCOperand::createReg(MO.getReg());
174     return true;
175   case MachineOperand::MO_Immediate:
176     OutMO = MCOperand::createImm(MO.getImm());
177     return true;
178   case MachineOperand::MO_MachineBasicBlock:
179     OutMO = MCOperand::createExpr(
180         MCSymbolRefExpr::create(MO.getMBB()->getSymbol(), AP.OutContext));
181     return true;
182   case MachineOperand::MO_GlobalAddress:
183   case MachineOperand::MO_ExternalSymbol:
184     OutMO = GetSymbolRef(MO, GetSymbolFromOperand(MO, AP), AP, IsDarwin);
185     return true;
186   case MachineOperand::MO_JumpTableIndex:
187     OutMO = GetSymbolRef(MO, AP.GetJTISymbol(MO.getIndex()), AP, IsDarwin);
188     return true;
189   case MachineOperand::MO_ConstantPoolIndex:
190     OutMO = GetSymbolRef(MO, AP.GetCPISymbol(MO.getIndex()), AP, IsDarwin);
191     return true;
192   case MachineOperand::MO_BlockAddress:
193     OutMO = GetSymbolRef(MO, AP.GetBlockAddressSymbol(MO.getBlockAddress()), AP,
194                          IsDarwin);
195     return true;
196   case MachineOperand::MO_MCSymbol:
197     OutMO = GetSymbolRef(MO, MO.getMCSymbol(), AP, IsDarwin);
198     return true;
199   case MachineOperand::MO_RegisterMask:
200     return false;
201   }
202 }
203