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 "PPC.h"
16 #include "PPCSubtarget.h"
17 #include "MCTargetDesc/PPCMCExpr.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/IR/GlobalValue.h"
24 #include "llvm/MC/MCAsmInfo.h"
25 #include "llvm/MC/MCExpr.h"
26 #include "llvm/MC/MCInst.h"
27 #include "llvm/Target/Mangler.h"
28 #include "llvm/Target/TargetMachine.h"
29 using namespace llvm;
30 
31 static MachineModuleInfoMachO &getMachOMMI(AsmPrinter &AP) {
32   return AP.MMI->getObjFileInfo<MachineModuleInfoMachO>();
33 }
34 
35 
36 static MCSymbol *GetSymbolFromOperand(const MachineOperand &MO, AsmPrinter &AP){
37   const TargetMachine &TM = AP.TM;
38   MCContext &Ctx = AP.OutContext;
39   bool isDarwin = TM.getSubtarget<PPCSubtarget>().isDarwin();
40 
41   SmallString<128> Name;
42   if (!MO.isGlobal()) {
43     assert(MO.isSymbol() && "Isn't a symbol reference");
44     Name += AP.MAI->getGlobalPrefix();
45     Name += MO.getSymbolName();
46   } else {
47     const GlobalValue *GV = MO.getGlobal();
48     bool isImplicitlyPrivate = false;
49     if (MO.getTargetFlags() == PPCII::MO_PLT_OR_STUB ||
50         (MO.getTargetFlags() & PPCII::MO_NLP_FLAG))
51       isImplicitlyPrivate = true;
52 
53     AP.Mang->getNameWithPrefix(Name, GV, isImplicitlyPrivate);
54   }
55 
56   // If the target flags on the operand changes the name of the symbol, do that
57   // before we return the symbol.
58   if (MO.getTargetFlags() == PPCII::MO_PLT_OR_STUB && isDarwin) {
59     Name += "$stub";
60     const char *PGP = AP.MAI->getPrivateGlobalPrefix();
61     const char *Prefix = "";
62     if (!Name.startswith(PGP)) {
63       // http://llvm.org/bugs/show_bug.cgi?id=15763
64       // all stubs and lazy_ptrs should be local symbols, which need leading 'L'
65       Prefix = PGP;
66     }
67     MCSymbol *Sym = Ctx.GetOrCreateSymbol(Twine(Prefix) + Twine(Name));
68     MachineModuleInfoImpl::StubValueTy &StubSym =
69       getMachOMMI(AP).getFnStubEntry(Sym);
70     if (StubSym.getPointer())
71       return Sym;
72 
73     if (MO.isGlobal()) {
74       StubSym =
75       MachineModuleInfoImpl::
76       StubValueTy(AP.getSymbol(MO.getGlobal()),
77                   !MO.getGlobal()->hasInternalLinkage());
78     } else {
79       Name.erase(Name.end()-5, Name.end());
80       StubSym =
81       MachineModuleInfoImpl::
82       StubValueTy(Ctx.GetOrCreateSymbol(Name.str()), false);
83     }
84     return Sym;
85   }
86 
87   // If the symbol reference is actually to a non_lazy_ptr, not to the symbol,
88   // then add the suffix.
89   if (MO.getTargetFlags() & PPCII::MO_NLP_FLAG) {
90     Name += "$non_lazy_ptr";
91     MCSymbol *Sym = Ctx.GetOrCreateSymbol(Name.str());
92 
93     MachineModuleInfoMachO &MachO = getMachOMMI(AP);
94 
95     MachineModuleInfoImpl::StubValueTy &StubSym =
96       (MO.getTargetFlags() & PPCII::MO_NLP_HIDDEN_FLAG) ?
97          MachO.getHiddenGVStubEntry(Sym) : MachO.getGVStubEntry(Sym);
98 
99     if (StubSym.getPointer() == 0) {
100       assert(MO.isGlobal() && "Extern symbol not handled yet");
101       StubSym = MachineModuleInfoImpl::
102                    StubValueTy(AP.getSymbol(MO.getGlobal()),
103                                !MO.getGlobal()->hasInternalLinkage());
104     }
105     return Sym;
106   }
107 
108   return Ctx.GetOrCreateSymbol(Name.str());
109 }
110 
111 static MCOperand GetSymbolRef(const MachineOperand &MO, const MCSymbol *Symbol,
112                               AsmPrinter &Printer, bool isDarwin) {
113   MCContext &Ctx = Printer.OutContext;
114   MCSymbolRefExpr::VariantKind RefKind = MCSymbolRefExpr::VK_None;
115 
116   unsigned access = MO.getTargetFlags() & PPCII::MO_ACCESS_MASK;
117 
118   switch (access) {
119     case PPCII::MO_TPREL_LO:
120       RefKind = MCSymbolRefExpr::VK_PPC_TPREL_LO;
121       break;
122     case PPCII::MO_TPREL_HA:
123       RefKind = MCSymbolRefExpr::VK_PPC_TPREL_HA;
124       break;
125     case PPCII::MO_DTPREL_LO:
126       RefKind = MCSymbolRefExpr::VK_PPC_DTPREL_LO;
127       break;
128     case PPCII::MO_TLSLD_LO:
129       RefKind = MCSymbolRefExpr::VK_PPC_GOT_TLSLD_LO;
130       break;
131     case PPCII::MO_TOC_LO:
132       RefKind = MCSymbolRefExpr::VK_PPC_TOC_LO;
133       break;
134     case PPCII::MO_TLS:
135       RefKind = MCSymbolRefExpr::VK_PPC_TLS;
136       break;
137   }
138 
139   if (MO.getTargetFlags() == PPCII::MO_PLT_OR_STUB && !isDarwin)
140     RefKind = MCSymbolRefExpr::VK_PLT;
141 
142   const MCExpr *Expr = MCSymbolRefExpr::Create(Symbol, RefKind, Ctx);
143 
144   if (!MO.isJTI() && MO.getOffset())
145     Expr = MCBinaryExpr::CreateAdd(Expr,
146                                    MCConstantExpr::Create(MO.getOffset(), Ctx),
147                                    Ctx);
148 
149   // Subtract off the PIC base if required.
150   if (MO.getTargetFlags() & PPCII::MO_PIC_FLAG) {
151     const MachineFunction *MF = MO.getParent()->getParent()->getParent();
152 
153     const MCExpr *PB = MCSymbolRefExpr::Create(MF->getPICBaseSymbol(), Ctx);
154     Expr = MCBinaryExpr::CreateSub(Expr, PB, Ctx);
155   }
156 
157   // Add ha16() / lo16() markers if required.
158   switch (access) {
159     case PPCII::MO_LO:
160       Expr = PPCMCExpr::CreateLo(Expr, isDarwin, Ctx);
161       break;
162     case PPCII::MO_HA:
163       Expr = PPCMCExpr::CreateHa(Expr, isDarwin, Ctx);
164       break;
165   }
166 
167   return MCOperand::CreateExpr(Expr);
168 }
169 
170 void llvm::LowerPPCMachineInstrToMCInst(const MachineInstr *MI, MCInst &OutMI,
171                                         AsmPrinter &AP, bool isDarwin) {
172   OutMI.setOpcode(MI->getOpcode());
173 
174   for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
175     const MachineOperand &MO = MI->getOperand(i);
176 
177     MCOperand MCOp;
178     switch (MO.getType()) {
179     default:
180       MI->dump();
181       llvm_unreachable("unknown operand type");
182     case MachineOperand::MO_Register:
183       assert(!MO.getSubReg() && "Subregs should be eliminated!");
184       MCOp = MCOperand::CreateReg(MO.getReg());
185       break;
186     case MachineOperand::MO_Immediate:
187       MCOp = MCOperand::CreateImm(MO.getImm());
188       break;
189     case MachineOperand::MO_MachineBasicBlock:
190       MCOp = MCOperand::CreateExpr(MCSymbolRefExpr::Create(
191                                       MO.getMBB()->getSymbol(), AP.OutContext));
192       break;
193     case MachineOperand::MO_GlobalAddress:
194     case MachineOperand::MO_ExternalSymbol:
195       MCOp = GetSymbolRef(MO, GetSymbolFromOperand(MO, AP), AP, isDarwin);
196       break;
197     case MachineOperand::MO_JumpTableIndex:
198       MCOp = GetSymbolRef(MO, AP.GetJTISymbol(MO.getIndex()), AP, isDarwin);
199       break;
200     case MachineOperand::MO_ConstantPoolIndex:
201       MCOp = GetSymbolRef(MO, AP.GetCPISymbol(MO.getIndex()), AP, isDarwin);
202       break;
203     case MachineOperand::MO_BlockAddress:
204       MCOp = GetSymbolRef(MO,AP.GetBlockAddressSymbol(MO.getBlockAddress()),AP,
205                           isDarwin);
206       break;
207     case MachineOperand::MO_RegisterMask:
208       continue;
209     }
210 
211     OutMI.addOperand(MCOp);
212   }
213 }
214