llvm/lib/Target/AArch64/AArch64MCInstLower.cpp

   1 //==-- AArch64MCInstLower.cpp - Convert AArch64 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 AArch64 MachineInstrs to their corresponding
  10 // MCInst records.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "AArch64MCInstLower.h"
  15 #include "MCTargetDesc/AArch64MCExpr.h"
  16 #include "Utils/AArch64BaseInfo.h"
  17 #include "llvm/CodeGen/AsmPrinter.h"
  18 #include "llvm/CodeGen/MachineBasicBlock.h"
  19 #include "llvm/CodeGen/MachineInstr.h"
  20 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
  21 #include "llvm/IR/Mangler.h"
  22 #include "llvm/MC/MCContext.h"
  23 #include "llvm/MC/MCExpr.h"
  24 #include "llvm/MC/MCInst.h"
  25 #include "llvm/Support/CodeGen.h"
  26 #include "llvm/Support/CommandLine.h"
  27 #include "llvm/Target/TargetLoweringObjectFile.h"
  28 #include "llvm/Target/TargetMachine.h"
  29 using namespace llvm;
  30
  31 extern cl::opt<bool> EnableAArch64ELFLocalDynamicTLSGeneration;
  32
  33 AArch64MCInstLower::AArch64MCInstLower(MCContext &ctx, AsmPrinter &printer)
  34     : Ctx(ctx), Printer(printer) {}
  35
  36 MCSymbol *
  37 AArch64MCInstLower::GetGlobalAddressSymbol(const MachineOperand &MO) const {
  38   const GlobalValue *GV = MO.getGlobal();
  39   unsigned TargetFlags = MO.getTargetFlags();
  40   const Triple &TheTriple = Printer.TM.getTargetTriple();
  41   if (!TheTriple.isOSBinFormatCOFF())
  42     return Printer.getSymbolPreferLocal(*GV);
  43
  44   assert(TheTriple.isOSWindows() &&
  45          "Windows is the only supported COFF target");
  46
  47   bool IsIndirect = (TargetFlags & (AArch64II::MO_DLLIMPORT | AArch64II::MO_COFFSTUB));
  48   if (!IsIndirect)
  49     return Printer.getSymbol(GV);
  50
  51   SmallString<128> Name;
  52   if (TargetFlags & AArch64II::MO_DLLIMPORT)
  53     Name = "__imp_";
  54   else if (TargetFlags & AArch64II::MO_COFFSTUB)
  55     Name = ".refptr.";
  56   Printer.TM.getNameWithPrefix(Name, GV,
  57                                Printer.getObjFileLowering().getMangler());
  58
  59   MCSymbol *MCSym = Ctx.getOrCreateSymbol(Name);
  60
  61   if (TargetFlags & AArch64II::MO_COFFSTUB) {
  62     MachineModuleInfoCOFF &MMICOFF =
  63         Printer.MMI->getObjFileInfo<MachineModuleInfoCOFF>();
  64     MachineModuleInfoImpl::StubValueTy &StubSym =
  65         MMICOFF.getGVStubEntry(MCSym);
  66
  67     if (!StubSym.getPointer())
  68       StubSym = MachineModuleInfoImpl::StubValueTy(Printer.getSymbol(GV), true);
  69   }
  70
  71   return MCSym;
  72 }
  73
  74 MCSymbol *
  75 AArch64MCInstLower::GetExternalSymbolSymbol(const MachineOperand &MO) const {
  76   return Printer.GetExternalSymbolSymbol(MO.getSymbolName());
  77 }
  78
  79 MCOperand AArch64MCInstLower::lowerSymbolOperandDarwin(const MachineOperand &MO,
  80                                                        MCSymbol *Sym) const {
  81   // FIXME: We would like an efficient form for this, so we don't have to do a
  82   // lot of extra uniquing.
  83   MCSymbolRefExpr::VariantKind RefKind = MCSymbolRefExpr::VK_None;
  84   if ((MO.getTargetFlags() & AArch64II::MO_GOT) != 0) {
  85     if ((MO.getTargetFlags() & AArch64II::MO_FRAGMENT) == AArch64II::MO_PAGE)
  86       RefKind = MCSymbolRefExpr::VK_GOTPAGE;
  87     else if ((MO.getTargetFlags() & AArch64II::MO_FRAGMENT) ==
  88              AArch64II::MO_PAGEOFF)
  89       RefKind = MCSymbolRefExpr::VK_GOTPAGEOFF;
  90     else
  91       llvm_unreachable("Unexpected target flags with MO_GOT on GV operand");
  92   } else if ((MO.getTargetFlags() & AArch64II::MO_TLS) != 0) {
  93     if ((MO.getTargetFlags() & AArch64II::MO_FRAGMENT) == AArch64II::MO_PAGE)
  94       RefKind = MCSymbolRefExpr::VK_TLVPPAGE;
  95     else if ((MO.getTargetFlags() & AArch64II::MO_FRAGMENT) ==
  96              AArch64II::MO_PAGEOFF)
  97       RefKind = MCSymbolRefExpr::VK_TLVPPAGEOFF;
  98     else
  99       llvm_unreachable("Unexpected target flags with MO_TLS on GV operand");
 100   } else {
 101     if ((MO.getTargetFlags() & AArch64II::MO_FRAGMENT) == AArch64II::MO_PAGE)
 102       RefKind = MCSymbolRefExpr::VK_PAGE;
 103     else if ((MO.getTargetFlags() & AArch64II::MO_FRAGMENT) ==
 104              AArch64II::MO_PAGEOFF)
 105       RefKind = MCSymbolRefExpr::VK_PAGEOFF;
 106   }
 107   const MCExpr *Expr = MCSymbolRefExpr::create(Sym, RefKind, Ctx);
 108   if (!MO.isJTI() && MO.getOffset())
 109     Expr = MCBinaryExpr::createAdd(
 110         Expr, MCConstantExpr::create(MO.getOffset(), Ctx), Ctx);
 111   return MCOperand::createExpr(Expr);
 112 }
 113
 114 MCOperand AArch64MCInstLower::lowerSymbolOperandELF(const MachineOperand &MO,
 115                                                     MCSymbol *Sym) const {
 116   uint32_t RefFlags = 0;
 117
 118   if (MO.getTargetFlags() & AArch64II::MO_GOT)
 119     RefFlags |= AArch64MCExpr::VK_GOT;
 120   else if (MO.getTargetFlags() & AArch64II::MO_TLS) {
 121     TLSModel::Model Model;
 122     if (MO.isGlobal()) {
 123       const GlobalValue *GV = MO.getGlobal();
 124       Model = Printer.TM.getTLSModel(GV);
 125       if (!EnableAArch64ELFLocalDynamicTLSGeneration &&
 126           Model == TLSModel::LocalDynamic)
 127         Model = TLSModel::GeneralDynamic;
 128
 129     } else {
 130       assert(MO.isSymbol() &&
 131              StringRef(MO.getSymbolName()) == "_TLS_MODULE_BASE_" &&
 132              "unexpected external TLS symbol");
 133       // The general dynamic access sequence is used to get the
 134       // address of _TLS_MODULE_BASE_.
 135       Model = TLSModel::GeneralDynamic;
 136     }
 137     switch (Model) {
 138     case TLSModel::InitialExec:
 139       RefFlags |= AArch64MCExpr::VK_GOTTPREL;
 140       break;
 141     case TLSModel::LocalExec:
 142       RefFlags |= AArch64MCExpr::VK_TPREL;
 143       break;
 144     case TLSModel::LocalDynamic:
 145       RefFlags |= AArch64MCExpr::VK_DTPREL;
 146       break;
 147     case TLSModel::GeneralDynamic:
 148       RefFlags |= AArch64MCExpr::VK_TLSDESC;
 149       break;
 150     }
 151   } else if (MO.getTargetFlags() & AArch64II::MO_PREL) {
 152     RefFlags |= AArch64MCExpr::VK_PREL;
 153   } else {
 154     // No modifier means this is a generic reference, classified as absolute for
 155     // the cases where it matters (:abs_g0: etc).
 156     RefFlags |= AArch64MCExpr::VK_ABS;
 157   }
 158
 159   if ((MO.getTargetFlags() & AArch64II::MO_FRAGMENT) == AArch64II::MO_PAGE)
 160     RefFlags |= AArch64MCExpr::VK_PAGE;
 161   else if ((MO.getTargetFlags() & AArch64II::MO_FRAGMENT) ==
 162            AArch64II::MO_PAGEOFF)
 163     RefFlags |= AArch64MCExpr::VK_PAGEOFF;
 164   else if ((MO.getTargetFlags() & AArch64II::MO_FRAGMENT) == AArch64II::MO_G3)
 165     RefFlags |= AArch64MCExpr::VK_G3;
 166   else if ((MO.getTargetFlags() & AArch64II::MO_FRAGMENT) == AArch64II::MO_G2)
 167     RefFlags |= AArch64MCExpr::VK_G2;
 168   else if ((MO.getTargetFlags() & AArch64II::MO_FRAGMENT) == AArch64II::MO_G1)
 169     RefFlags |= AArch64MCExpr::VK_G1;
 170   else if ((MO.getTargetFlags() & AArch64II::MO_FRAGMENT) == AArch64II::MO_G0)
 171     RefFlags |= AArch64MCExpr::VK_G0;
 172   else if ((MO.getTargetFlags() & AArch64II::MO_FRAGMENT) == AArch64II::MO_HI12)
 173     RefFlags |= AArch64MCExpr::VK_HI12;
 174
 175   if (MO.getTargetFlags() & AArch64II::MO_NC)
 176     RefFlags |= AArch64MCExpr::VK_NC;
 177
 178   const MCExpr *Expr =
 179       MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_None, Ctx);
 180   if (!MO.isJTI() && MO.getOffset())
 181     Expr = MCBinaryExpr::createAdd(
 182         Expr, MCConstantExpr::create(MO.getOffset(), Ctx), Ctx);
 183
 184   AArch64MCExpr::VariantKind RefKind;
 185   RefKind = static_cast<AArch64MCExpr::VariantKind>(RefFlags);
 186   Expr = AArch64MCExpr::create(Expr, RefKind, Ctx);
 187
 188   return MCOperand::createExpr(Expr);
 189 }
 190
 191 MCOperand AArch64MCInstLower::lowerSymbolOperandCOFF(const MachineOperand &MO,
 192                                                      MCSymbol *Sym) const {
 193   uint32_t RefFlags = 0;
 194
 195   if (MO.getTargetFlags() & AArch64II::MO_TLS) {
 196     if ((MO.getTargetFlags() & AArch64II::MO_FRAGMENT) == AArch64II::MO_PAGEOFF)
 197       RefFlags |= AArch64MCExpr::VK_SECREL_LO12;
 198     else if ((MO.getTargetFlags() & AArch64II::MO_FRAGMENT) ==
 199              AArch64II::MO_HI12)
 200       RefFlags |= AArch64MCExpr::VK_SECREL_HI12;
 201
 202   } else if (MO.getTargetFlags() & AArch64II::MO_S) {
 203     RefFlags |= AArch64MCExpr::VK_SABS;
 204   } else {
 205     RefFlags |= AArch64MCExpr::VK_ABS;
 206
 207     if ((MO.getTargetFlags() & AArch64II::MO_FRAGMENT) == AArch64II::MO_PAGE)
 208       RefFlags |= AArch64MCExpr::VK_PAGE;
 209     else if ((MO.getTargetFlags() & AArch64II::MO_FRAGMENT) ==
 210              AArch64II::MO_PAGEOFF)
 211       RefFlags |= AArch64MCExpr::VK_PAGEOFF | AArch64MCExpr::VK_NC;
 212   }
 213
 214   if ((MO.getTargetFlags() & AArch64II::MO_FRAGMENT) == AArch64II::MO_G3)
 215     RefFlags |= AArch64MCExpr::VK_G3;
 216   else if ((MO.getTargetFlags() & AArch64II::MO_FRAGMENT) == AArch64II::MO_G2)
 217     RefFlags |= AArch64MCExpr::VK_G2;
 218   else if ((MO.getTargetFlags() & AArch64II::MO_FRAGMENT) == AArch64II::MO_G1)
 219     RefFlags |= AArch64MCExpr::VK_G1;
 220   else if ((MO.getTargetFlags() & AArch64II::MO_FRAGMENT) == AArch64II::MO_G0)
 221     RefFlags |= AArch64MCExpr::VK_G0;
 222
 223   // FIXME: Currently we only set VK_NC for MO_G3/MO_G2/MO_G1/MO_G0. This is
 224   // because setting VK_NC for others would mean setting their respective
 225   // RefFlags correctly.  We should do this in a separate patch.
 226   if (MO.getTargetFlags() & AArch64II::MO_NC) {
 227     auto MOFrag = (MO.getTargetFlags() & AArch64II::MO_FRAGMENT);
 228     if (MOFrag == AArch64II::MO_G3 || MOFrag == AArch64II::MO_G2 ||
 229         MOFrag == AArch64II::MO_G1 || MOFrag == AArch64II::MO_G0)
 230       RefFlags |= AArch64MCExpr::VK_NC;
 231   }
 232
 233   const MCExpr *Expr =
 234       MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_None, Ctx);
 235   if (!MO.isJTI() && MO.getOffset())
 236     Expr = MCBinaryExpr::createAdd(
 237         Expr, MCConstantExpr::create(MO.getOffset(), Ctx), Ctx);
 238
 239   auto RefKind = static_cast<AArch64MCExpr::VariantKind>(RefFlags);
 240   assert(RefKind != AArch64MCExpr::VK_INVALID &&
 241          "Invalid relocation requested");
 242   Expr = AArch64MCExpr::create(Expr, RefKind, Ctx);
 243
 244   return MCOperand::createExpr(Expr);
 245 }
 246
 247 MCOperand AArch64MCInstLower::LowerSymbolOperand(const MachineOperand &MO,
 248                                                  MCSymbol *Sym) const {
 249   if (Printer.TM.getTargetTriple().isOSDarwin())
 250     return lowerSymbolOperandDarwin(MO, Sym);
 251   if (Printer.TM.getTargetTriple().isOSBinFormatCOFF())
 252     return lowerSymbolOperandCOFF(MO, Sym);
 253
 254   assert(Printer.TM.getTargetTriple().isOSBinFormatELF() && "Invalid target");
 255   return lowerSymbolOperandELF(MO, Sym);
 256 }
 257
 258 bool AArch64MCInstLower::lowerOperand(const MachineOperand &MO,
 259                                       MCOperand &MCOp) const {
 260   switch (MO.getType()) {
 261   default:
 262     llvm_unreachable("unknown operand type");
 263   case MachineOperand::MO_Register:
 264     // Ignore all implicit register operands.
 265     if (MO.isImplicit())
 266       return false;
 267     MCOp = MCOperand::createReg(MO.getReg());
 268     break;
 269   case MachineOperand::MO_RegisterMask:
 270     // Regmasks are like implicit defs.
 271     return false;
 272   case MachineOperand::MO_Immediate:
 273     MCOp = MCOperand::createImm(MO.getImm());
 274     break;
 275   case MachineOperand::MO_MachineBasicBlock:
 276     MCOp = MCOperand::createExpr(
 277         MCSymbolRefExpr::create(MO.getMBB()->getSymbol(), Ctx));
 278     break;
 279   case MachineOperand::MO_GlobalAddress:
 280     MCOp = LowerSymbolOperand(MO, GetGlobalAddressSymbol(MO));
 281     break;
 282   case MachineOperand::MO_ExternalSymbol:
 283     MCOp = LowerSymbolOperand(MO, GetExternalSymbolSymbol(MO));
 284     break;
 285   case MachineOperand::MO_MCSymbol:
 286     MCOp = LowerSymbolOperand(MO, MO.getMCSymbol());
 287     break;
 288   case MachineOperand::MO_JumpTableIndex:
 289     MCOp = LowerSymbolOperand(MO, Printer.GetJTISymbol(MO.getIndex()));
 290     break;
 291   case MachineOperand::MO_ConstantPoolIndex:
 292     MCOp = LowerSymbolOperand(MO, Printer.GetCPISymbol(MO.getIndex()));
 293     break;
 294   case MachineOperand::MO_BlockAddress:
 295     MCOp = LowerSymbolOperand(
 296         MO, Printer.GetBlockAddressSymbol(MO.getBlockAddress()));
 297     break;
 298   }
 299   return true;
 300 }
 301
 302 void AArch64MCInstLower::Lower(const MachineInstr *MI, MCInst &OutMI) const {
 303   OutMI.setOpcode(MI->getOpcode());
 304
 305   for (const MachineOperand &MO : MI->operands()) {
 306     MCOperand MCOp;
 307     if (lowerOperand(MO, MCOp))
 308       OutMI.addOperand(MCOp);
 309   }
 310
 311   switch (OutMI.getOpcode()) {
 312   case AArch64::CATCHRET:
 313     OutMI = MCInst();
 314     OutMI.setOpcode(AArch64::RET);
 315     OutMI.addOperand(MCOperand::createReg(AArch64::LR));
 316     break;
 317   case AArch64::CLEANUPRET:
 318     OutMI = MCInst();
 319     OutMI.setOpcode(AArch64::RET);
 320     OutMI.addOperand(MCOperand::createReg(AArch64::LR));
 321     break;
 322   }
 323 }