lib/Target/Mips/MCTargetDesc/MipsMCExpr.cpp

   1 //===-- MipsMCExpr.cpp - Mips specific MC expression classes --------------===//
   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 #include "MipsMCExpr.h"
  10 #include "llvm/BinaryFormat/ELF.h"
  11 #include "llvm/MC/MCAsmInfo.h"
  12 #include "llvm/MC/MCAssembler.h"
  13 #include "llvm/MC/MCContext.h"
  14 #include "llvm/MC/MCStreamer.h"
  15 #include "llvm/MC/MCSymbolELF.h"
  16 #include "llvm/MC/MCValue.h"
  17 #include "llvm/Support/Casting.h"
  18 #include "llvm/Support/ErrorHandling.h"
  19 #include "llvm/Support/MathExtras.h"
  20 #include "llvm/Support/raw_ostream.h"
  21 #include <cstdint>
  22
  23 using namespace llvm;
  24
  25 #define DEBUG_TYPE "mipsmcexpr"
  26
  27 const MipsMCExpr *MipsMCExpr::create(MipsMCExpr::MipsExprKind Kind,
  28                                      const MCExpr *Expr, MCContext &Ctx) {
  29   return new (Ctx) MipsMCExpr(Kind, Expr);
  30 }
  31
  32 const MipsMCExpr *MipsMCExpr::createGpOff(MipsMCExpr::MipsExprKind Kind,
  33                                           const MCExpr *Expr, MCContext &Ctx) {
  34   return create(Kind, create(MEK_NEG, create(MEK_GPREL, Expr, Ctx), Ctx), Ctx);
  35 }
  36
  37 void MipsMCExpr::printImpl(raw_ostream &OS, const MCAsmInfo *MAI) const {
  38   int64_t AbsVal;
  39
  40   switch (Kind) {
  41   case MEK_None:
  42   case MEK_Special:
  43     llvm_unreachable("MEK_None and MEK_Special are invalid");
  44     break;
  45   case MEK_DTPREL:
  46     // MEK_DTPREL is used for marking TLS DIEExpr only
  47     // and contains a regular sub-expression.
  48     getSubExpr()->print(OS, MAI, true);
  49     return;
  50   case MEK_CALL_HI16:
  51     OS << "%call_hi";
  52     break;
  53   case MEK_CALL_LO16:
  54     OS << "%call_lo";
  55     break;
  56   case MEK_DTPREL_HI:
  57     OS << "%dtprel_hi";
  58     break;
  59   case MEK_DTPREL_LO:
  60     OS << "%dtprel_lo";
  61     break;
  62   case MEK_GOT:
  63     OS << "%got";
  64     break;
  65   case MEK_GOTTPREL:
  66     OS << "%gottprel";
  67     break;
  68   case MEK_GOT_CALL:
  69     OS << "%call16";
  70     break;
  71   case MEK_GOT_DISP:
  72     OS << "%got_disp";
  73     break;
  74   case MEK_GOT_HI16:
  75     OS << "%got_hi";
  76     break;
  77   case MEK_GOT_LO16:
  78     OS << "%got_lo";
  79     break;
  80   case MEK_GOT_PAGE:
  81     OS << "%got_page";
  82     break;
  83   case MEK_GOT_OFST:
  84     OS << "%got_ofst";
  85     break;
  86   case MEK_GPREL:
  87     OS << "%gp_rel";
  88     break;
  89   case MEK_HI:
  90     OS << "%hi";
  91     break;
  92   case MEK_HIGHER:
  93     OS << "%higher";
  94     break;
  95   case MEK_HIGHEST:
  96     OS << "%highest";
  97     break;
  98   case MEK_LO:
  99     OS << "%lo";
 100     break;
 101   case MEK_NEG:
 102     OS << "%neg";
 103     break;
 104   case MEK_PCREL_HI16:
 105     OS << "%pcrel_hi";
 106     break;
 107   case MEK_PCREL_LO16:
 108     OS << "%pcrel_lo";
 109     break;
 110   case MEK_TLSGD:
 111     OS << "%tlsgd";
 112     break;
 113   case MEK_TLSLDM:
 114     OS << "%tlsldm";
 115     break;
 116   case MEK_TPREL_HI:
 117     OS << "%tprel_hi";
 118     break;
 119   case MEK_TPREL_LO:
 120     OS << "%tprel_lo";
 121     break;
 122   }
 123
 124   OS << '(';
 125   if (Expr->evaluateAsAbsolute(AbsVal))
 126     OS << AbsVal;
 127   else
 128     Expr->print(OS, MAI, true);
 129   OS << ')';
 130 }
 131
 132 bool
 133 MipsMCExpr::evaluateAsRelocatableImpl(MCValue &Res,
 134                                       const MCAsmLayout *Layout,
 135                                       const MCFixup *Fixup) const {
 136   // Look for the %hi(%neg(%gp_rel(X))) and %lo(%neg(%gp_rel(X))) special cases.
 137   if (isGpOff()) {
 138     const MCExpr *SubExpr =
 139         cast<MipsMCExpr>(cast<MipsMCExpr>(getSubExpr())->getSubExpr())
 140             ->getSubExpr();
 141     if (!SubExpr->evaluateAsRelocatable(Res, Layout, Fixup))
 142       return false;
 143
 144     Res = MCValue::get(Res.getSymA(), Res.getSymB(), Res.getConstant(),
 145                        MEK_Special);
 146     return true;
 147   }
 148
 149   if (!getSubExpr()->evaluateAsRelocatable(Res, Layout, Fixup))
 150     return false;
 151
 152   if (Res.getRefKind() != MCSymbolRefExpr::VK_None)
 153     return false;
 154
 155   // evaluateAsAbsolute() and evaluateAsValue() require that we evaluate the
 156   // %hi/%lo/etc. here. Fixup is a null pointer when either of these is the
 157   // caller.
 158   if (Res.isAbsolute() && Fixup == nullptr) {
 159     int64_t AbsVal = Res.getConstant();
 160     switch (Kind) {
 161     case MEK_None:
 162     case MEK_Special:
 163       llvm_unreachable("MEK_None and MEK_Special are invalid");
 164     case MEK_DTPREL:
 165       // MEK_DTPREL is used for marking TLS DIEExpr only
 166       // and contains a regular sub-expression.
 167       return getSubExpr()->evaluateAsRelocatable(Res, Layout, Fixup);
 168     case MEK_DTPREL_HI:
 169     case MEK_DTPREL_LO:
 170     case MEK_GOT:
 171     case MEK_GOTTPREL:
 172     case MEK_GOT_CALL:
 173     case MEK_GOT_DISP:
 174     case MEK_GOT_HI16:
 175     case MEK_GOT_LO16:
 176     case MEK_GOT_OFST:
 177     case MEK_GOT_PAGE:
 178     case MEK_GPREL:
 179     case MEK_PCREL_HI16:
 180     case MEK_PCREL_LO16:
 181     case MEK_TLSGD:
 182     case MEK_TLSLDM:
 183     case MEK_TPREL_HI:
 184     case MEK_TPREL_LO:
 185       return false;
 186     case MEK_LO:
 187     case MEK_CALL_LO16:
 188       AbsVal = SignExtend64<16>(AbsVal);
 189       break;
 190     case MEK_CALL_HI16:
 191     case MEK_HI:
 192       AbsVal = SignExtend64<16>((AbsVal + 0x8000) >> 16);
 193       break;
 194     case MEK_HIGHER:
 195       AbsVal = SignExtend64<16>((AbsVal + 0x80008000LL) >> 32);
 196       break;
 197     case MEK_HIGHEST:
 198       AbsVal = SignExtend64<16>((AbsVal + 0x800080008000LL) >> 48);
 199       break;
 200     case MEK_NEG:
 201       AbsVal = -AbsVal;
 202       break;
 203     }
 204     Res = MCValue::get(AbsVal);
 205     return true;
 206   }
 207
 208   // We want to defer it for relocatable expressions since the constant is
 209   // applied to the whole symbol value.
 210   //
 211   // The value of getKind() that is given to MCValue is only intended to aid
 212   // debugging when inspecting MCValue objects. It shouldn't be relied upon
 213   // for decision making.
 214   Res = MCValue::get(Res.getSymA(), Res.getSymB(), Res.getConstant(), getKind());
 215
 216   return true;
 217 }
 218
 219 void MipsMCExpr::visitUsedExpr(MCStreamer &Streamer) const {
 220   Streamer.visitUsedExpr(*getSubExpr());
 221 }
 222
 223 static void fixELFSymbolsInTLSFixupsImpl(const MCExpr *Expr, MCAssembler &Asm) {
 224   switch (Expr->getKind()) {
 225   case MCExpr::Target:
 226     fixELFSymbolsInTLSFixupsImpl(cast<MipsMCExpr>(Expr)->getSubExpr(), Asm);
 227     break;
 228   case MCExpr::Constant:
 229     break;
 230   case MCExpr::Binary: {
 231     const MCBinaryExpr *BE = cast<MCBinaryExpr>(Expr);
 232     fixELFSymbolsInTLSFixupsImpl(BE->getLHS(), Asm);
 233     fixELFSymbolsInTLSFixupsImpl(BE->getRHS(), Asm);
 234     break;
 235   }
 236   case MCExpr::SymbolRef: {
 237     // We're known to be under a TLS fixup, so any symbol should be
 238     // modified. There should be only one.
 239     const MCSymbolRefExpr &SymRef = *cast<MCSymbolRefExpr>(Expr);
 240     cast<MCSymbolELF>(SymRef.getSymbol()).setType(ELF::STT_TLS);
 241     break;
 242   }
 243   case MCExpr::Unary:
 244     fixELFSymbolsInTLSFixupsImpl(cast<MCUnaryExpr>(Expr)->getSubExpr(), Asm);
 245     break;
 246   }
 247 }
 248
 249 void MipsMCExpr::fixELFSymbolsInTLSFixups(MCAssembler &Asm) const {
 250   switch (getKind()) {
 251   case MEK_None:
 252   case MEK_Special:
 253     llvm_unreachable("MEK_None and MEK_Special are invalid");
 254     break;
 255   case MEK_CALL_HI16:
 256   case MEK_CALL_LO16:
 257   case MEK_GOT:
 258   case MEK_GOT_CALL:
 259   case MEK_GOT_DISP:
 260   case MEK_GOT_HI16:
 261   case MEK_GOT_LO16:
 262   case MEK_GOT_OFST:
 263   case MEK_GOT_PAGE:
 264   case MEK_GPREL:
 265   case MEK_HI:
 266   case MEK_HIGHER:
 267   case MEK_HIGHEST:
 268   case MEK_LO:
 269   case MEK_NEG:
 270   case MEK_PCREL_HI16:
 271   case MEK_PCREL_LO16:
 272     // If we do have nested target-specific expressions, they will be in
 273     // a consecutive chain.
 274     if (const MipsMCExpr *E = dyn_cast<const MipsMCExpr>(getSubExpr()))
 275       E->fixELFSymbolsInTLSFixups(Asm);
 276     break;
 277   case MEK_DTPREL:
 278   case MEK_DTPREL_HI:
 279   case MEK_DTPREL_LO:
 280   case MEK_TLSLDM:
 281   case MEK_TLSGD:
 282   case MEK_GOTTPREL:
 283   case MEK_TPREL_HI:
 284   case MEK_TPREL_LO:
 285     fixELFSymbolsInTLSFixupsImpl(getSubExpr(), Asm);
 286     break;
 287   }
 288 }
 289
 290 bool MipsMCExpr::isGpOff(MipsExprKind &Kind) const {
 291   if (getKind() == MEK_HI || getKind() == MEK_LO) {
 292     if (const MipsMCExpr *S1 = dyn_cast<const MipsMCExpr>(getSubExpr())) {
 293       if (const MipsMCExpr *S2 = dyn_cast<const MipsMCExpr>(S1->getSubExpr())) {
 294         if (S1->getKind() == MEK_NEG && S2->getKind() == MEK_GPREL) {
 295           Kind = getKind();
 296           return true;
 297         }
 298       }
 299     }
 300   }
 301   return false;
 302 }