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