1 //===-- RISCVMCExpr.cpp - RISC-V 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 RISC-V 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/MCAssembler.h" 19 #include "llvm/MC/MCContext.h" 20 #include "llvm/MC/MCStreamer.h" 21 #include "llvm/MC/MCSymbolELF.h" 22 #include "llvm/MC/MCValue.h" 23 #include "llvm/Support/Casting.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 (HasVariant) 44 OS << ')'; 45 } 46 47 const MCFixup *RISCVMCExpr::getPCRelHiFixup(const MCFragment **DFOut) const { 48 MCValue AUIPCLoc; 49 if (!getSubExpr()->evaluateAsRelocatable(AUIPCLoc, nullptr, nullptr)) 50 return nullptr; 51 52 const MCSymbolRefExpr *AUIPCSRE = AUIPCLoc.getSymA(); 53 if (!AUIPCSRE) 54 return nullptr; 55 56 const MCSymbol *AUIPCSymbol = &AUIPCSRE->getSymbol(); 57 const auto *DF = dyn_cast_or_null<MCDataFragment>(AUIPCSymbol->getFragment()); 58 59 if (!DF) 60 return nullptr; 61 62 uint64_t Offset = AUIPCSymbol->getOffset(); 63 if (DF->getContents().size() == Offset) { 64 DF = dyn_cast_or_null<MCDataFragment>(DF->getNext()); 65 if (!DF) 66 return nullptr; 67 Offset = 0; 68 } 69 70 for (const MCFixup &F : DF->getFixups()) { 71 if (F.getOffset() != Offset) 72 continue; 73 74 switch ((unsigned)F.getKind()) { 75 default: 76 continue; 77 case RISCV::fixup_riscv_got_hi20: 78 case RISCV::fixup_riscv_tls_got_hi20: 79 case RISCV::fixup_riscv_tls_gd_hi20: 80 case RISCV::fixup_riscv_pcrel_hi20: 81 case RISCV::fixup_riscv_tlsdesc_hi20: 82 if (DFOut) 83 *DFOut = DF; 84 return &F; 85 } 86 } 87 88 return nullptr; 89 } 90 91 bool RISCVMCExpr::evaluateAsRelocatableImpl(MCValue &Res, 92 const MCAssembler *Asm, 93 const MCFixup *Fixup) const { 94 // Explicitly drop the layout and assembler to prevent any symbolic folding in 95 // the expression handling. This is required to preserve symbolic difference 96 // expressions to emit the paired relocations. 97 if (!getSubExpr()->evaluateAsRelocatable(Res, nullptr, nullptr)) 98 return false; 99 100 Res = 101 MCValue::get(Res.getSymA(), Res.getSymB(), Res.getConstant(), getKind()); 102 // Custom fixup types are not valid with symbol difference expressions. 103 return Res.getSymB() ? getKind() == VK_RISCV_None : true; 104 } 105 106 void RISCVMCExpr::visitUsedExpr(MCStreamer &Streamer) const { 107 Streamer.visitUsedExpr(*getSubExpr()); 108 } 109 110 RISCVMCExpr::VariantKind RISCVMCExpr::getVariantKindForName(StringRef name) { 111 return StringSwitch<RISCVMCExpr::VariantKind>(name) 112 .Case("lo", VK_RISCV_LO) 113 .Case("hi", VK_RISCV_HI) 114 .Case("pcrel_lo", VK_RISCV_PCREL_LO) 115 .Case("pcrel_hi", VK_RISCV_PCREL_HI) 116 .Case("got_pcrel_hi", VK_RISCV_GOT_HI) 117 .Case("tprel_lo", VK_RISCV_TPREL_LO) 118 .Case("tprel_hi", VK_RISCV_TPREL_HI) 119 .Case("tprel_add", VK_RISCV_TPREL_ADD) 120 .Case("tls_ie_pcrel_hi", VK_RISCV_TLS_GOT_HI) 121 .Case("tls_gd_pcrel_hi", VK_RISCV_TLS_GD_HI) 122 .Case("tlsdesc_hi", VK_RISCV_TLSDESC_HI) 123 .Case("tlsdesc_load_lo", VK_RISCV_TLSDESC_LOAD_LO) 124 .Case("tlsdesc_add_lo", VK_RISCV_TLSDESC_ADD_LO) 125 .Case("tlsdesc_call", VK_RISCV_TLSDESC_CALL) 126 .Default(VK_RISCV_Invalid); 127 } 128 129 StringRef RISCVMCExpr::getVariantKindName(VariantKind Kind) { 130 switch (Kind) { 131 case VK_RISCV_Invalid: 132 case VK_RISCV_None: 133 llvm_unreachable("Invalid ELF symbol kind"); 134 case VK_RISCV_LO: 135 return "lo"; 136 case VK_RISCV_HI: 137 return "hi"; 138 case VK_RISCV_PCREL_LO: 139 return "pcrel_lo"; 140 case VK_RISCV_PCREL_HI: 141 return "pcrel_hi"; 142 case VK_RISCV_GOT_HI: 143 return "got_pcrel_hi"; 144 case VK_RISCV_TPREL_LO: 145 return "tprel_lo"; 146 case VK_RISCV_TPREL_HI: 147 return "tprel_hi"; 148 case VK_RISCV_TPREL_ADD: 149 return "tprel_add"; 150 case VK_RISCV_TLS_GOT_HI: 151 return "tls_ie_pcrel_hi"; 152 case VK_RISCV_TLSDESC_HI: 153 return "tlsdesc_hi"; 154 case VK_RISCV_TLSDESC_LOAD_LO: 155 return "tlsdesc_load_lo"; 156 case VK_RISCV_TLSDESC_ADD_LO: 157 return "tlsdesc_add_lo"; 158 case VK_RISCV_TLSDESC_CALL: 159 return "tlsdesc_call"; 160 case VK_RISCV_TLS_GD_HI: 161 return "tls_gd_pcrel_hi"; 162 case VK_RISCV_CALL: 163 return "call"; 164 case VK_RISCV_CALL_PLT: 165 return "call_plt"; 166 case VK_RISCV_32_PCREL: 167 return "32_pcrel"; 168 } 169 llvm_unreachable("Invalid ELF symbol kind"); 170 } 171 172 static void fixELFSymbolsInTLSFixupsImpl(const MCExpr *Expr, MCAssembler &Asm) { 173 switch (Expr->getKind()) { 174 case MCExpr::Target: 175 llvm_unreachable("Can't handle nested target expression"); 176 break; 177 case MCExpr::Constant: 178 break; 179 180 case MCExpr::Binary: { 181 const MCBinaryExpr *BE = cast<MCBinaryExpr>(Expr); 182 fixELFSymbolsInTLSFixupsImpl(BE->getLHS(), Asm); 183 fixELFSymbolsInTLSFixupsImpl(BE->getRHS(), Asm); 184 break; 185 } 186 187 case MCExpr::SymbolRef: { 188 // We're known to be under a TLS fixup, so any symbol should be 189 // modified. There should be only one. 190 const MCSymbolRefExpr &SymRef = *cast<MCSymbolRefExpr>(Expr); 191 cast<MCSymbolELF>(SymRef.getSymbol()).setType(ELF::STT_TLS); 192 break; 193 } 194 195 case MCExpr::Unary: 196 fixELFSymbolsInTLSFixupsImpl(cast<MCUnaryExpr>(Expr)->getSubExpr(), Asm); 197 break; 198 } 199 } 200 201 void RISCVMCExpr::fixELFSymbolsInTLSFixups(MCAssembler &Asm) const { 202 switch (getKind()) { 203 default: 204 return; 205 case VK_RISCV_TPREL_HI: 206 case VK_RISCV_TLS_GOT_HI: 207 case VK_RISCV_TLS_GD_HI: 208 case VK_RISCV_TLSDESC_HI: 209 break; 210 } 211 212 fixELFSymbolsInTLSFixupsImpl(getSubExpr(), Asm); 213 } 214 215 bool RISCVMCExpr::evaluateAsConstant(int64_t &Res) const { 216 MCValue Value; 217 218 if (Kind == VK_RISCV_PCREL_HI || Kind == VK_RISCV_PCREL_LO || 219 Kind == VK_RISCV_GOT_HI || Kind == VK_RISCV_TPREL_HI || 220 Kind == VK_RISCV_TPREL_LO || Kind == VK_RISCV_TPREL_ADD || 221 Kind == VK_RISCV_TLS_GOT_HI || Kind == VK_RISCV_TLS_GD_HI || 222 Kind == VK_RISCV_TLSDESC_HI || Kind == VK_RISCV_TLSDESC_LOAD_LO || 223 Kind == VK_RISCV_TLSDESC_ADD_LO || Kind == VK_RISCV_TLSDESC_CALL || 224 Kind == VK_RISCV_CALL || Kind == VK_RISCV_CALL_PLT) 225 return false; 226 227 if (!getSubExpr()->evaluateAsRelocatable(Value, nullptr, nullptr)) 228 return false; 229 230 if (!Value.isAbsolute()) 231 return false; 232 233 Res = evaluateAsInt64(Value.getConstant()); 234 return true; 235 } 236 237 int64_t RISCVMCExpr::evaluateAsInt64(int64_t Value) const { 238 switch (Kind) { 239 default: 240 llvm_unreachable("Invalid kind"); 241 case VK_RISCV_LO: 242 return SignExtend64<12>(Value); 243 case VK_RISCV_HI: 244 // Add 1 if bit 11 is 1, to compensate for low 12 bits being negative. 245 return ((Value + 0x800) >> 12) & 0xfffff; 246 } 247 } 248