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 
GetSymbolFromOperand(const MachineOperand & MO,AsmPrinter & AP)32 static MCSymbol *GetSymbolFromOperand(const MachineOperand &MO,
33                                       AsmPrinter &AP) {
34   const TargetMachine &TM = AP.TM;
35   Mangler &Mang = TM.getObjFileLowering()->getMangler();
36   const DataLayout &DL = AP.getDataLayout();
37   MCContext &Ctx = AP.OutContext;
38 
39   SmallString<128> Name;
40   if (!MO.isGlobal()) {
41     assert(MO.isSymbol() && "Isn't a symbol reference");
42     Mangler::getNameWithPrefix(Name, MO.getSymbolName(), DL);
43   } else {
44     const GlobalValue *GV = MO.getGlobal();
45     TM.getNameWithPrefix(Name, GV, Mang);
46   }
47 
48   MCSymbol *Sym = Ctx.getOrCreateSymbol(Name);
49 
50   return Sym;
51 }
52 
GetSymbolRef(const MachineOperand & MO,const MCSymbol * Symbol,AsmPrinter & Printer)53 static MCOperand GetSymbolRef(const MachineOperand &MO, const MCSymbol *Symbol,
54                               AsmPrinter &Printer) {
55   MCContext &Ctx = Printer.OutContext;
56   MCSymbolRefExpr::VariantKind RefKind = MCSymbolRefExpr::VK_None;
57 
58   unsigned access = MO.getTargetFlags() & PPCII::MO_ACCESS_MASK;
59 
60   switch (access) {
61     case PPCII::MO_TPREL_LO:
62       RefKind = MCSymbolRefExpr::VK_PPC_TPREL_LO;
63       break;
64     case PPCII::MO_TPREL_HA:
65       RefKind = MCSymbolRefExpr::VK_PPC_TPREL_HA;
66       break;
67     case PPCII::MO_DTPREL_LO:
68       RefKind = MCSymbolRefExpr::VK_PPC_DTPREL_LO;
69       break;
70     case PPCII::MO_TLSLD_LO:
71       RefKind = MCSymbolRefExpr::VK_PPC_GOT_TLSLD_LO;
72       break;
73     case PPCII::MO_TOC_LO:
74       RefKind = MCSymbolRefExpr::VK_PPC_TOC_LO;
75       break;
76     case PPCII::MO_TLS:
77       bool IsPCRel = (MO.getTargetFlags() & ~access) == PPCII::MO_PCREL_FLAG;
78       RefKind = IsPCRel ? MCSymbolRefExpr::VK_PPC_TLS_PCREL
79                         : MCSymbolRefExpr::VK_PPC_TLS;
80       break;
81   }
82 
83   if (MO.getTargetFlags() == PPCII::MO_PLT)
84     RefKind = MCSymbolRefExpr::VK_PLT;
85   else if (MO.getTargetFlags() == PPCII::MO_PCREL_FLAG)
86     RefKind = MCSymbolRefExpr::VK_PCREL;
87   else if (MO.getTargetFlags() == (PPCII::MO_PCREL_FLAG | PPCII::MO_GOT_FLAG))
88     RefKind = MCSymbolRefExpr::VK_PPC_GOT_PCREL;
89   else if (MO.getTargetFlags() == (PPCII::MO_PCREL_FLAG | PPCII::MO_TPREL_FLAG))
90     RefKind = MCSymbolRefExpr::VK_TPREL;
91   else if (MO.getTargetFlags() == PPCII::MO_GOT_TLSGD_PCREL_FLAG)
92     RefKind = MCSymbolRefExpr::VK_PPC_GOT_TLSGD_PCREL;
93   else if (MO.getTargetFlags() == PPCII::MO_GOT_TLSLD_PCREL_FLAG)
94     RefKind = MCSymbolRefExpr::VK_PPC_GOT_TLSLD_PCREL;
95   else if (MO.getTargetFlags() == PPCII::MO_GOT_TPREL_PCREL_FLAG)
96     RefKind = MCSymbolRefExpr::VK_PPC_GOT_TPREL_PCREL;
97 
98   const MachineInstr *MI = MO.getParent();
99   const MachineFunction *MF = MI->getMF();
100   const Module *M = MF->getFunction().getParent();
101   const PPCSubtarget *Subtarget = &(MF->getSubtarget<PPCSubtarget>());
102   const TargetMachine &TM = Printer.TM;
103 
104   unsigned MIOpcode = MI->getOpcode();
105   assert((Subtarget->isUsingPCRelativeCalls() || MIOpcode != PPC::BL8_NOTOC) &&
106          "BL8_NOTOC is only valid when using PC Relative Calls.");
107   if (Subtarget->isUsingPCRelativeCalls()) {
108     if (MIOpcode == PPC::TAILB || MIOpcode == PPC::TAILB8 ||
109         MIOpcode == PPC::TCRETURNdi || MIOpcode == PPC::TCRETURNdi8 ||
110         MIOpcode == PPC::BL8_NOTOC || MIOpcode == PPC::BL8_NOTOC_RM) {
111       RefKind = MCSymbolRefExpr::VK_PPC_NOTOC;
112     }
113     if (MO.getTargetFlags() == PPCII::MO_PCREL_OPT_FLAG)
114       RefKind = MCSymbolRefExpr::VK_PPC_PCREL_OPT;
115   }
116 
117   const MCExpr *Expr = MCSymbolRefExpr::create(Symbol, RefKind, Ctx);
118   // If -msecure-plt -fPIC, add 32768 to symbol.
119   if (Subtarget->isSecurePlt() && TM.isPositionIndependent() &&
120       M->getPICLevel() == PICLevel::BigPIC &&
121       MO.getTargetFlags() == PPCII::MO_PLT)
122     Expr =
123         MCBinaryExpr::createAdd(Expr, MCConstantExpr::create(32768, Ctx), 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, Ctx);
142       break;
143     case PPCII::MO_HA:
144       Expr = PPCMCExpr::createHa(Expr, Ctx);
145       break;
146   }
147 
148   return MCOperand::createExpr(Expr);
149 }
150 
LowerPPCMachineInstrToMCInst(const MachineInstr * MI,MCInst & OutMI,AsmPrinter & AP)151 void llvm::LowerPPCMachineInstrToMCInst(const MachineInstr *MI, MCInst &OutMI,
152                                         AsmPrinter &AP) {
153   OutMI.setOpcode(MI->getOpcode());
154 
155   for (const MachineOperand &MO : MI->operands()) {
156     MCOperand MCOp;
157     if (LowerPPCMachineOperandToMCOperand(MO, MCOp, AP))
158       OutMI.addOperand(MCOp);
159   }
160 }
161 
LowerPPCMachineOperandToMCOperand(const MachineOperand & MO,MCOperand & OutMO,AsmPrinter & AP)162 bool llvm::LowerPPCMachineOperandToMCOperand(const MachineOperand &MO,
163                                              MCOperand &OutMO, AsmPrinter &AP) {
164   switch (MO.getType()) {
165   default:
166     llvm_unreachable("unknown operand type");
167   case MachineOperand::MO_Register:
168     assert(!MO.getSubReg() && "Subregs should be eliminated!");
169     assert(MO.getReg() > PPC::NoRegister &&
170            MO.getReg() < PPC::NUM_TARGET_REGS &&
171            "Invalid register for this target!");
172     // Ignore all implicit register operands.
173     if (MO.isImplicit())
174       return false;
175     OutMO = MCOperand::createReg(MO.getReg());
176     return true;
177   case MachineOperand::MO_Immediate:
178     OutMO = MCOperand::createImm(MO.getImm());
179     return true;
180   case MachineOperand::MO_MachineBasicBlock:
181     OutMO = MCOperand::createExpr(
182         MCSymbolRefExpr::create(MO.getMBB()->getSymbol(), AP.OutContext));
183     return true;
184   case MachineOperand::MO_GlobalAddress:
185   case MachineOperand::MO_ExternalSymbol:
186     OutMO = GetSymbolRef(MO, GetSymbolFromOperand(MO, AP), AP);
187     return true;
188   case MachineOperand::MO_JumpTableIndex:
189     OutMO = GetSymbolRef(MO, AP.GetJTISymbol(MO.getIndex()), AP);
190     return true;
191   case MachineOperand::MO_ConstantPoolIndex:
192     OutMO = GetSymbolRef(MO, AP.GetCPISymbol(MO.getIndex()), AP);
193     return true;
194   case MachineOperand::MO_BlockAddress:
195     OutMO =
196         GetSymbolRef(MO, AP.GetBlockAddressSymbol(MO.getBlockAddress()), AP);
197     return true;
198   case MachineOperand::MO_MCSymbol:
199     OutMO = GetSymbolRef(MO, MO.getMCSymbol(), AP);
200     return true;
201   case MachineOperand::MO_RegisterMask:
202     return false;
203   }
204 }
205