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