1 //===-- RISCVMCExpr.cpp - RISCV 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 // This file contains the implementation of the assembly expression modifiers 10 // accepted by the RISCV architecture (e.g. ":lo12:", ":gottprel_g1:", ...). 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "RISCVMCExpr.h" 15 #include "MCTargetDesc/RISCVAsmBackend.h" 16 #include "RISCVFixupKinds.h" 17 #include "llvm/BinaryFormat/ELF.h" 18 #include "llvm/MC/MCAsmLayout.h" 19 #include "llvm/MC/MCAssembler.h" 20 #include "llvm/MC/MCContext.h" 21 #include "llvm/MC/MCStreamer.h" 22 #include "llvm/MC/MCSymbolELF.h" 23 #include "llvm/MC/MCValue.h" 24 #include "llvm/Support/ErrorHandling.h" 25 26 using namespace llvm; 27 28 #define DEBUG_TYPE "riscvmcexpr" 29 30 const RISCVMCExpr *RISCVMCExpr::create(const MCExpr *Expr, VariantKind Kind, 31 MCContext &Ctx) { 32 return new (Ctx) RISCVMCExpr(Expr, Kind); 33 } 34 35 void RISCVMCExpr::printImpl(raw_ostream &OS, const MCAsmInfo *MAI) const { 36 VariantKind Kind = getKind(); 37 bool HasVariant = ((Kind != VK_RISCV_None) && (Kind != VK_RISCV_CALL) && 38 (Kind != VK_RISCV_CALL_PLT)); 39 40 if (HasVariant) 41 OS << '%' << getVariantKindName(getKind()) << '('; 42 Expr->print(OS, MAI); 43 if (Kind == VK_RISCV_CALL_PLT) 44 OS << "@plt"; 45 if (HasVariant) 46 OS << ')'; 47 } 48 49 const MCFixup *RISCVMCExpr::getPCRelHiFixup(const MCFragment **DFOut) const { 50 MCValue AUIPCLoc; 51 if (!getSubExpr()->evaluateAsRelocatable(AUIPCLoc, nullptr, nullptr)) 52 return nullptr; 53 54 const MCSymbolRefExpr *AUIPCSRE = AUIPCLoc.getSymA(); 55 if (!AUIPCSRE) 56 return nullptr; 57 58 const MCSymbol *AUIPCSymbol = &AUIPCSRE->getSymbol(); 59 const auto *DF = dyn_cast_or_null<MCDataFragment>(AUIPCSymbol->getFragment()); 60 61 if (!DF) 62 return nullptr; 63 64 uint64_t Offset = AUIPCSymbol->getOffset(); 65 if (DF->getContents().size() == Offset) { 66 DF = dyn_cast_or_null<MCDataFragment>(DF->getNextNode()); 67 if (!DF) 68 return nullptr; 69 Offset = 0; 70 } 71 72 for (const MCFixup &F : DF->getFixups()) { 73 if (F.getOffset() != Offset) 74 continue; 75 76 switch ((unsigned)F.getKind()) { 77 default: 78 continue; 79 case RISCV::fixup_riscv_got_hi20: 80 case RISCV::fixup_riscv_tls_got_hi20: 81 case RISCV::fixup_riscv_tls_gd_hi20: 82 case RISCV::fixup_riscv_pcrel_hi20: 83 if (DFOut) 84 *DFOut = DF; 85 return &F; 86 } 87 } 88 89 return nullptr; 90 } 91 92 bool RISCVMCExpr::evaluateAsRelocatableImpl(MCValue &Res, 93 const MCAsmLayout *Layout, 94 const MCFixup *Fixup) const { 95 if (!getSubExpr()->evaluateAsRelocatable(Res, Layout, Fixup)) 96 return false; 97 98 // Some custom fixup types are not valid with symbol difference expressions 99 if (Res.getSymA() && Res.getSymB()) { 100 switch (getKind()) { 101 default: 102 return true; 103 case VK_RISCV_LO: 104 case VK_RISCV_HI: 105 case VK_RISCV_PCREL_LO: 106 case VK_RISCV_PCREL_HI: 107 case VK_RISCV_GOT_HI: 108 case VK_RISCV_TPREL_LO: 109 case VK_RISCV_TPREL_HI: 110 case VK_RISCV_TPREL_ADD: 111 case VK_RISCV_TLS_GOT_HI: 112 case VK_RISCV_TLS_GD_HI: 113 return false; 114 } 115 } 116 117 return true; 118 } 119 120 void RISCVMCExpr::visitUsedExpr(MCStreamer &Streamer) const { 121 Streamer.visitUsedExpr(*getSubExpr()); 122 } 123 124 RISCVMCExpr::VariantKind RISCVMCExpr::getVariantKindForName(StringRef name) { 125 return StringSwitch<RISCVMCExpr::VariantKind>(name) 126 .Case("lo", VK_RISCV_LO) 127 .Case("hi", VK_RISCV_HI) 128 .Case("pcrel_lo", VK_RISCV_PCREL_LO) 129 .Case("pcrel_hi", VK_RISCV_PCREL_HI) 130 .Case("got_pcrel_hi", VK_RISCV_GOT_HI) 131 .Case("tprel_lo", VK_RISCV_TPREL_LO) 132 .Case("tprel_hi", VK_RISCV_TPREL_HI) 133 .Case("tprel_add", VK_RISCV_TPREL_ADD) 134 .Case("tls_ie_pcrel_hi", VK_RISCV_TLS_GOT_HI) 135 .Case("tls_gd_pcrel_hi", VK_RISCV_TLS_GD_HI) 136 .Default(VK_RISCV_Invalid); 137 } 138 139 StringRef RISCVMCExpr::getVariantKindName(VariantKind Kind) { 140 switch (Kind) { 141 case VK_RISCV_Invalid: 142 case VK_RISCV_None: 143 llvm_unreachable("Invalid ELF symbol kind"); 144 case VK_RISCV_LO: 145 return "lo"; 146 case VK_RISCV_HI: 147 return "hi"; 148 case VK_RISCV_PCREL_LO: 149 return "pcrel_lo"; 150 case VK_RISCV_PCREL_HI: 151 return "pcrel_hi"; 152 case VK_RISCV_GOT_HI: 153 return "got_pcrel_hi"; 154 case VK_RISCV_TPREL_LO: 155 return "tprel_lo"; 156 case VK_RISCV_TPREL_HI: 157 return "tprel_hi"; 158 case VK_RISCV_TPREL_ADD: 159 return "tprel_add"; 160 case VK_RISCV_TLS_GOT_HI: 161 return "tls_ie_pcrel_hi"; 162 case VK_RISCV_TLS_GD_HI: 163 return "tls_gd_pcrel_hi"; 164 case VK_RISCV_CALL: 165 return "call"; 166 case VK_RISCV_CALL_PLT: 167 return "call_plt"; 168 case VK_RISCV_32_PCREL: 169 return "32_pcrel"; 170 } 171 llvm_unreachable("Invalid ELF symbol kind"); 172 } 173 174 static void fixELFSymbolsInTLSFixupsImpl(const MCExpr *Expr, MCAssembler &Asm) { 175 switch (Expr->getKind()) { 176 case MCExpr::Target: 177 llvm_unreachable("Can't handle nested target expression"); 178 break; 179 case MCExpr::Constant: 180 break; 181 182 case MCExpr::Binary: { 183 const MCBinaryExpr *BE = cast<MCBinaryExpr>(Expr); 184 fixELFSymbolsInTLSFixupsImpl(BE->getLHS(), Asm); 185 fixELFSymbolsInTLSFixupsImpl(BE->getRHS(), Asm); 186 break; 187 } 188 189 case MCExpr::SymbolRef: { 190 // We're known to be under a TLS fixup, so any symbol should be 191 // modified. There should be only one. 192 const MCSymbolRefExpr &SymRef = *cast<MCSymbolRefExpr>(Expr); 193 cast<MCSymbolELF>(SymRef.getSymbol()).setType(ELF::STT_TLS); 194 break; 195 } 196 197 case MCExpr::Unary: 198 fixELFSymbolsInTLSFixupsImpl(cast<MCUnaryExpr>(Expr)->getSubExpr(), Asm); 199 break; 200 } 201 } 202 203 void RISCVMCExpr::fixELFSymbolsInTLSFixups(MCAssembler &Asm) const { 204 switch (getKind()) { 205 default: 206 return; 207 case VK_RISCV_TPREL_HI: 208 case VK_RISCV_TLS_GOT_HI: 209 case VK_RISCV_TLS_GD_HI: 210 break; 211 } 212 213 fixELFSymbolsInTLSFixupsImpl(getSubExpr(), Asm); 214 } 215 216 bool RISCVMCExpr::evaluateAsConstant(int64_t &Res) const { 217 MCValue Value; 218 219 if (Kind == VK_RISCV_PCREL_HI || Kind == VK_RISCV_PCREL_LO || 220 Kind == VK_RISCV_GOT_HI || Kind == VK_RISCV_TPREL_HI || 221 Kind == VK_RISCV_TPREL_LO || Kind == VK_RISCV_TPREL_ADD || 222 Kind == VK_RISCV_TLS_GOT_HI || Kind == VK_RISCV_TLS_GD_HI || 223 Kind == VK_RISCV_CALL || Kind == VK_RISCV_CALL_PLT) 224 return false; 225 226 if (!getSubExpr()->evaluateAsRelocatable(Value, nullptr, nullptr)) 227 return false; 228 229 if (!Value.isAbsolute()) 230 return false; 231 232 Res = evaluateAsInt64(Value.getConstant()); 233 return true; 234 } 235 236 int64_t RISCVMCExpr::evaluateAsInt64(int64_t Value) const { 237 switch (Kind) { 238 default: 239 llvm_unreachable("Invalid kind"); 240 case VK_RISCV_LO: 241 return SignExtend64<12>(Value); 242 case VK_RISCV_HI: 243 // Add 1 if bit 11 is 1, to compensate for low 12 bits being negative. 244 return ((Value + 0x800) >> 12) & 0xfffff; 245 } 246 } 247