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 "llvm/ADT/SmallString.h"
17 #include "llvm/ADT/Twine.h"
18 #include "llvm/CodeGen/AsmPrinter.h"
19 #include "llvm/CodeGen/MachineFunction.h"
20 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
21 #include "llvm/IR/GlobalValue.h"
22 #include "llvm/MC/MCAsmInfo.h"
23 #include "llvm/MC/MCExpr.h"
24 #include "llvm/MC/MCInst.h"
25 #include "llvm/Target/Mangler.h"
26 using namespace llvm;
27 
28 static MachineModuleInfoMachO &getMachOMMI(AsmPrinter &AP) {
29   return AP.MMI->getObjFileInfo<MachineModuleInfoMachO>();
30 }
31 
32 
33 static MCSymbol *GetSymbolFromOperand(const MachineOperand &MO, AsmPrinter &AP){
34   MCContext &Ctx = AP.OutContext;
35 
36   SmallString<128> Name;
37   if (!MO.isGlobal()) {
38     assert(MO.isSymbol() && "Isn't a symbol reference");
39     Name += AP.MAI->getGlobalPrefix();
40     Name += MO.getSymbolName();
41   } else {
42     const GlobalValue *GV = MO.getGlobal();
43     bool isImplicitlyPrivate = false;
44     if (MO.getTargetFlags() == PPCII::MO_DARWIN_STUB ||
45         (MO.getTargetFlags() & PPCII::MO_NLP_FLAG))
46       isImplicitlyPrivate = true;
47 
48     AP.Mang->getNameWithPrefix(Name, GV, isImplicitlyPrivate);
49   }
50 
51   // If the target flags on the operand changes the name of the symbol, do that
52   // before we return the symbol.
53   if (MO.getTargetFlags() == PPCII::MO_DARWIN_STUB) {
54     Name += "$stub";
55     const char *PGP = AP.MAI->getPrivateGlobalPrefix();
56     const char *Prefix = "";
57     if (!Name.startswith(PGP)) {
58       // http://llvm.org/bugs/show_bug.cgi?id=15763
59       // all stubs and lazy_ptrs should be local symbols, which need leading 'L'
60       Prefix = PGP;
61     }
62     MCSymbol *Sym = Ctx.GetOrCreateSymbol(Twine(Prefix) + Twine(Name));
63     MachineModuleInfoImpl::StubValueTy &StubSym =
64       getMachOMMI(AP).getFnStubEntry(Sym);
65     if (StubSym.getPointer())
66       return Sym;
67 
68     if (MO.isGlobal()) {
69       StubSym =
70       MachineModuleInfoImpl::
71       StubValueTy(AP.Mang->getSymbol(MO.getGlobal()),
72                   !MO.getGlobal()->hasInternalLinkage());
73     } else {
74       Name.erase(Name.end()-5, Name.end());
75       StubSym =
76       MachineModuleInfoImpl::
77       StubValueTy(Ctx.GetOrCreateSymbol(Name.str()), false);
78     }
79     return Sym;
80   }
81 
82   // If the symbol reference is actually to a non_lazy_ptr, not to the symbol,
83   // then add the suffix.
84   if (MO.getTargetFlags() & PPCII::MO_NLP_FLAG) {
85     Name += "$non_lazy_ptr";
86     MCSymbol *Sym = Ctx.GetOrCreateSymbol(Name.str());
87 
88     MachineModuleInfoMachO &MachO = getMachOMMI(AP);
89 
90     MachineModuleInfoImpl::StubValueTy &StubSym =
91       (MO.getTargetFlags() & PPCII::MO_NLP_HIDDEN_FLAG) ?
92          MachO.getHiddenGVStubEntry(Sym) : MachO.getGVStubEntry(Sym);
93 
94     if (StubSym.getPointer() == 0) {
95       assert(MO.isGlobal() && "Extern symbol not handled yet");
96       StubSym = MachineModuleInfoImpl::
97                    StubValueTy(AP.Mang->getSymbol(MO.getGlobal()),
98                                !MO.getGlobal()->hasInternalLinkage());
99     }
100     return Sym;
101   }
102 
103   return Ctx.GetOrCreateSymbol(Name.str());
104 }
105 
106 static MCOperand GetSymbolRef(const MachineOperand &MO, const MCSymbol *Symbol,
107                               AsmPrinter &Printer, bool isDarwin) {
108   MCContext &Ctx = Printer.OutContext;
109   MCSymbolRefExpr::VariantKind RefKind = MCSymbolRefExpr::VK_None;
110 
111   unsigned access = MO.getTargetFlags() & PPCII::MO_ACCESS_MASK;
112 
113   switch (access) {
114     case PPCII::MO_HA16: RefKind = isDarwin ?
115                            MCSymbolRefExpr::VK_PPC_DARWIN_HA16 :
116                            MCSymbolRefExpr::VK_PPC_GAS_HA16;
117                          break;
118     case PPCII::MO_LO16: RefKind = isDarwin ?
119                            MCSymbolRefExpr::VK_PPC_DARWIN_LO16 :
120                            MCSymbolRefExpr::VK_PPC_GAS_LO16;
121                          break;
122     case PPCII::MO_TPREL16_HA: RefKind = MCSymbolRefExpr::VK_PPC_TPREL16_HA;
123                                break;
124     case PPCII::MO_TPREL16_LO: RefKind = MCSymbolRefExpr::VK_PPC_TPREL16_LO;
125                                break;
126     case PPCII::MO_DTPREL16_LO: RefKind = MCSymbolRefExpr::VK_PPC_DTPREL16_LO;
127                                 break;
128     case PPCII::MO_TLSLD16_LO: RefKind = MCSymbolRefExpr::VK_PPC_GOT_TLSLD16_LO;
129                                break;
130     case PPCII::MO_TOC16_LO: RefKind = MCSymbolRefExpr::VK_PPC_TOC16_LO;
131                              break;
132    }
133 
134   // FIXME: This isn't right, but we don't have a good way to express this in
135   // the MC Level, see below.
136   if (MO.getTargetFlags() & PPCII::MO_PIC_FLAG)
137     RefKind = MCSymbolRefExpr::VK_None;
138 
139   const MCExpr *Expr = MCSymbolRefExpr::Create(Symbol, RefKind, Ctx);
140 
141   if (!MO.isJTI() && MO.getOffset())
142     Expr = MCBinaryExpr::CreateAdd(Expr,
143                                    MCConstantExpr::Create(MO.getOffset(), Ctx),
144                                    Ctx);
145 
146   // Subtract off the PIC base if required.
147   if (MO.getTargetFlags() & PPCII::MO_PIC_FLAG) {
148     const MachineFunction *MF = MO.getParent()->getParent()->getParent();
149 
150     const MCExpr *PB = MCSymbolRefExpr::Create(MF->getPICBaseSymbol(), Ctx);
151     Expr = MCBinaryExpr::CreateSub(Expr, PB, Ctx);
152     // FIXME: We have no way to make the result be VK_PPC_LO16/VK_PPC_HA16,
153     // since it is not a symbol!
154   }
155 
156   return MCOperand::CreateExpr(Expr);
157 }
158 
159 void llvm::LowerPPCMachineInstrToMCInst(const MachineInstr *MI, MCInst &OutMI,
160                                         AsmPrinter &AP, bool isDarwin) {
161   OutMI.setOpcode(MI->getOpcode());
162 
163   for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
164     const MachineOperand &MO = MI->getOperand(i);
165 
166     MCOperand MCOp;
167     switch (MO.getType()) {
168     default:
169       MI->dump();
170       llvm_unreachable("unknown operand type");
171     case MachineOperand::MO_Register:
172       assert(!MO.getSubReg() && "Subregs should be eliminated!");
173       MCOp = MCOperand::CreateReg(MO.getReg());
174       break;
175     case MachineOperand::MO_Immediate:
176       MCOp = MCOperand::CreateImm(MO.getImm());
177       break;
178     case MachineOperand::MO_MachineBasicBlock:
179       MCOp = MCOperand::CreateExpr(MCSymbolRefExpr::Create(
180                                       MO.getMBB()->getSymbol(), AP.OutContext));
181       break;
182     case MachineOperand::MO_GlobalAddress:
183     case MachineOperand::MO_ExternalSymbol:
184       MCOp = GetSymbolRef(MO, GetSymbolFromOperand(MO, AP), AP, isDarwin);
185       break;
186     case MachineOperand::MO_JumpTableIndex:
187       MCOp = GetSymbolRef(MO, AP.GetJTISymbol(MO.getIndex()), AP, isDarwin);
188       break;
189     case MachineOperand::MO_ConstantPoolIndex:
190       MCOp = GetSymbolRef(MO, AP.GetCPISymbol(MO.getIndex()), AP, isDarwin);
191       break;
192     case MachineOperand::MO_BlockAddress:
193       MCOp = GetSymbolRef(MO,AP.GetBlockAddressSymbol(MO.getBlockAddress()),AP,
194                           isDarwin);
195       break;
196     case MachineOperand::MO_RegisterMask:
197       continue;
198     }
199 
200     OutMI.addOperand(MCOp);
201   }
202 }
203