//===- MCExpr.cpp - Assembly Level Expression Implementation --------------===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// #include "llvm/MC/MCExpr.h" #include "llvm/ADT/Statistic.h" #include "llvm/ADT/StringSwitch.h" #include "llvm/MC/MCAsmInfo.h" #include "llvm/MC/MCAsmLayout.h" #include "llvm/MC/MCAssembler.h" #include "llvm/MC/MCContext.h" #include "llvm/MC/MCObjectWriter.h" #include "llvm/MC/MCSymbol.h" #include "llvm/MC/MCValue.h" #include "llvm/Support/Debug.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/raw_ostream.h" using namespace llvm; #define DEBUG_TYPE "mcexpr" namespace { namespace stats { STATISTIC(MCExprEvaluate, "Number of MCExpr evaluations"); } } void MCExpr::print(raw_ostream &OS) const { switch (getKind()) { case MCExpr::Target: return cast<MCTargetExpr>(this)->PrintImpl(OS); case MCExpr::Constant: OS << cast<MCConstantExpr>(*this).getValue(); return; case MCExpr::SymbolRef: { const MCSymbolRefExpr &SRE = cast<MCSymbolRefExpr>(*this); const MCSymbol &Sym = SRE.getSymbol(); // Parenthesize names that start with $ so that they don't look like // absolute names. bool UseParens = Sym.getName()[0] == '$'; if (UseParens) OS << '(' << Sym << ')'; else OS << Sym; if (SRE.getKind() != MCSymbolRefExpr::VK_None) { if (SRE.getMCAsmInfo().useParensForSymbolVariant()) OS << '(' << MCSymbolRefExpr::getVariantKindName(SRE.getKind()) << ')'; else OS << '@' << MCSymbolRefExpr::getVariantKindName(SRE.getKind()); } return; } case MCExpr::Unary: { const MCUnaryExpr &UE = cast<MCUnaryExpr>(*this); switch (UE.getOpcode()) { case MCUnaryExpr::LNot: OS << '!'; break; case MCUnaryExpr::Minus: OS << '-'; break; case MCUnaryExpr::Not: OS << '~'; break; case MCUnaryExpr::Plus: OS << '+'; break; } OS << *UE.getSubExpr(); return; } case MCExpr::Binary: { const MCBinaryExpr &BE = cast<MCBinaryExpr>(*this); // Only print parens around the LHS if it is non-trivial. if (isa<MCConstantExpr>(BE.getLHS()) || isa<MCSymbolRefExpr>(BE.getLHS())) { OS << *BE.getLHS(); } else { OS << '(' << *BE.getLHS() << ')'; } switch (BE.getOpcode()) { case MCBinaryExpr::Add: // Print "X-42" instead of "X+-42". if (const MCConstantExpr *RHSC = dyn_cast<MCConstantExpr>(BE.getRHS())) { if (RHSC->getValue() < 0) { OS << RHSC->getValue(); return; } } OS << '+'; break; case MCBinaryExpr::And: OS << '&'; break; case MCBinaryExpr::Div: OS << '/'; break; case MCBinaryExpr::EQ: OS << "=="; break; case MCBinaryExpr::GT: OS << '>'; break; case MCBinaryExpr::GTE: OS << ">="; break; case MCBinaryExpr::LAnd: OS << "&&"; break; case MCBinaryExpr::LOr: OS << "||"; break; case MCBinaryExpr::LT: OS << '<'; break; case MCBinaryExpr::LTE: OS << "<="; break; case MCBinaryExpr::Mod: OS << '%'; break; case MCBinaryExpr::Mul: OS << '*'; break; case MCBinaryExpr::NE: OS << "!="; break; case MCBinaryExpr::Or: OS << '|'; break; case MCBinaryExpr::Shl: OS << "<<"; break; case MCBinaryExpr::Shr: OS << ">>"; break; case MCBinaryExpr::Sub: OS << '-'; break; case MCBinaryExpr::Xor: OS << '^'; break; } // Only print parens around the LHS if it is non-trivial. if (isa<MCConstantExpr>(BE.getRHS()) || isa<MCSymbolRefExpr>(BE.getRHS())) { OS << *BE.getRHS(); } else { OS << '(' << *BE.getRHS() << ')'; } return; } } llvm_unreachable("Invalid expression kind!"); } #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) void MCExpr::dump() const { print(dbgs()); dbgs() << '\n'; } #endif /* *** */ const MCBinaryExpr *MCBinaryExpr::Create(Opcode Opc, const MCExpr *LHS, const MCExpr *RHS, MCContext &Ctx) { return new (Ctx) MCBinaryExpr(Opc, LHS, RHS); } const MCUnaryExpr *MCUnaryExpr::Create(Opcode Opc, const MCExpr *Expr, MCContext &Ctx) { return new (Ctx) MCUnaryExpr(Opc, Expr); } const MCConstantExpr *MCConstantExpr::Create(int64_t Value, MCContext &Ctx) { return new (Ctx) MCConstantExpr(Value); } /* *** */ const MCSymbolRefExpr *MCSymbolRefExpr::Create(const MCSymbol *Sym, VariantKind Kind, MCContext &Ctx) { return new (Ctx) MCSymbolRefExpr(Sym, Kind, Ctx.getAsmInfo()); } const MCSymbolRefExpr *MCSymbolRefExpr::Create(StringRef Name, VariantKind Kind, MCContext &Ctx) { return Create(Ctx.GetOrCreateSymbol(Name), Kind, Ctx); } StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) { switch (Kind) { case VK_Invalid: return "<<invalid>>"; case VK_None: return "<<none>>"; case VK_GOT: return "GOT"; case VK_GOTOFF: return "GOTOFF"; case VK_GOTPCREL: return "GOTPCREL"; case VK_GOTTPOFF: return "GOTTPOFF"; case VK_INDNTPOFF: return "INDNTPOFF"; case VK_NTPOFF: return "NTPOFF"; case VK_GOTNTPOFF: return "GOTNTPOFF"; case VK_PLT: return "PLT"; case VK_TLSGD: return "TLSGD"; case VK_TLSLD: return "TLSLD"; case VK_TLSLDM: return "TLSLDM"; case VK_TPOFF: return "TPOFF"; case VK_DTPOFF: return "DTPOFF"; case VK_TLVP: return "TLVP"; case VK_TLVPPAGE: return "TLVPPAGE"; case VK_TLVPPAGEOFF: return "TLVPPAGEOFF"; case VK_PAGE: return "PAGE"; case VK_PAGEOFF: return "PAGEOFF"; case VK_GOTPAGE: return "GOTPAGE"; case VK_GOTPAGEOFF: return "GOTPAGEOFF"; case VK_SECREL: return "SECREL32"; case VK_WEAKREF: return "WEAKREF"; case VK_ARM_NONE: return "none"; case VK_ARM_TARGET1: return "target1"; case VK_ARM_TARGET2: return "target2"; case VK_ARM_PREL31: return "prel31"; case VK_ARM_TLSLDO: return "tlsldo"; case VK_ARM_TLSCALL: return "tlscall"; case VK_ARM_TLSDESC: return "tlsdesc"; case VK_ARM_TLSDESCSEQ: return "tlsdescseq"; case VK_PPC_LO: return "l"; case VK_PPC_HI: return "h"; case VK_PPC_HA: return "ha"; case VK_PPC_HIGHER: return "higher"; case VK_PPC_HIGHERA: return "highera"; case VK_PPC_HIGHEST: return "highest"; case VK_PPC_HIGHESTA: return "highesta"; case VK_PPC_GOT_LO: return "got@l"; case VK_PPC_GOT_HI: return "got@h"; case VK_PPC_GOT_HA: return "got@ha"; case VK_PPC_TOCBASE: return "tocbase"; case VK_PPC_TOC: return "toc"; case VK_PPC_TOC_LO: return "toc@l"; case VK_PPC_TOC_HI: return "toc@h"; case VK_PPC_TOC_HA: return "toc@ha"; case VK_PPC_DTPMOD: return "dtpmod"; case VK_PPC_TPREL: return "tprel"; case VK_PPC_TPREL_LO: return "tprel@l"; case VK_PPC_TPREL_HI: return "tprel@h"; case VK_PPC_TPREL_HA: return "tprel@ha"; case VK_PPC_TPREL_HIGHER: return "tprel@higher"; case VK_PPC_TPREL_HIGHERA: return "tprel@highera"; case VK_PPC_TPREL_HIGHEST: return "tprel@highest"; case VK_PPC_TPREL_HIGHESTA: return "tprel@highesta"; case VK_PPC_DTPREL: return "dtprel"; case VK_PPC_DTPREL_LO: return "dtprel@l"; case VK_PPC_DTPREL_HI: return "dtprel@h"; case VK_PPC_DTPREL_HA: return "dtprel@ha"; case VK_PPC_DTPREL_HIGHER: return "dtprel@higher"; case VK_PPC_DTPREL_HIGHERA: return "dtprel@highera"; case VK_PPC_DTPREL_HIGHEST: return "dtprel@highest"; case VK_PPC_DTPREL_HIGHESTA: return "dtprel@highesta"; case VK_PPC_GOT_TPREL: return "got@tprel"; case VK_PPC_GOT_TPREL_LO: return "got@tprel@l"; case VK_PPC_GOT_TPREL_HI: return "got@tprel@h"; case VK_PPC_GOT_TPREL_HA: return "got@tprel@ha"; case VK_PPC_GOT_DTPREL: return "got@dtprel"; case VK_PPC_GOT_DTPREL_LO: return "got@dtprel@l"; case VK_PPC_GOT_DTPREL_HI: return "got@dtprel@h"; case VK_PPC_GOT_DTPREL_HA: return "got@dtprel@ha"; case VK_PPC_TLS: return "tls"; case VK_PPC_GOT_TLSGD: return "got@tlsgd"; case VK_PPC_GOT_TLSGD_LO: return "got@tlsgd@l"; case VK_PPC_GOT_TLSGD_HI: return "got@tlsgd@h"; case VK_PPC_GOT_TLSGD_HA: return "got@tlsgd@ha"; case VK_PPC_TLSGD: return "tlsgd"; case VK_PPC_GOT_TLSLD: return "got@tlsld"; case VK_PPC_GOT_TLSLD_LO: return "got@tlsld@l"; case VK_PPC_GOT_TLSLD_HI: return "got@tlsld@h"; case VK_PPC_GOT_TLSLD_HA: return "got@tlsld@ha"; case VK_PPC_TLSLD: return "tlsld"; case VK_Mips_GPREL: return "GPREL"; case VK_Mips_GOT_CALL: return "GOT_CALL"; case VK_Mips_GOT16: return "GOT16"; case VK_Mips_GOT: return "GOT"; case VK_Mips_ABS_HI: return "ABS_HI"; case VK_Mips_ABS_LO: return "ABS_LO"; case VK_Mips_TLSGD: return "TLSGD"; case VK_Mips_TLSLDM: return "TLSLDM"; case VK_Mips_DTPREL_HI: return "DTPREL_HI"; case VK_Mips_DTPREL_LO: return "DTPREL_LO"; case VK_Mips_GOTTPREL: return "GOTTPREL"; case VK_Mips_TPREL_HI: return "TPREL_HI"; case VK_Mips_TPREL_LO: return "TPREL_LO"; case VK_Mips_GPOFF_HI: return "GPOFF_HI"; case VK_Mips_GPOFF_LO: return "GPOFF_LO"; case VK_Mips_GOT_DISP: return "GOT_DISP"; case VK_Mips_GOT_PAGE: return "GOT_PAGE"; case VK_Mips_GOT_OFST: return "GOT_OFST"; case VK_Mips_HIGHER: return "HIGHER"; case VK_Mips_HIGHEST: return "HIGHEST"; case VK_Mips_GOT_HI16: return "GOT_HI16"; case VK_Mips_GOT_LO16: return "GOT_LO16"; case VK_Mips_CALL_HI16: return "CALL_HI16"; case VK_Mips_CALL_LO16: return "CALL_LO16"; case VK_COFF_IMGREL32: return "IMGREL32"; } llvm_unreachable("Invalid variant kind"); } MCSymbolRefExpr::VariantKind MCSymbolRefExpr::getVariantKindForName(StringRef Name) { return StringSwitch<VariantKind>(Name) .Case("GOT", VK_GOT) .Case("got", VK_GOT) .Case("GOTOFF", VK_GOTOFF) .Case("gotoff", VK_GOTOFF) .Case("GOTPCREL", VK_GOTPCREL) .Case("gotpcrel", VK_GOTPCREL) .Case("GOT_PREL", VK_GOTPCREL) .Case("got_prel", VK_GOTPCREL) .Case("GOTTPOFF", VK_GOTTPOFF) .Case("gottpoff", VK_GOTTPOFF) .Case("INDNTPOFF", VK_INDNTPOFF) .Case("indntpoff", VK_INDNTPOFF) .Case("NTPOFF", VK_NTPOFF) .Case("ntpoff", VK_NTPOFF) .Case("GOTNTPOFF", VK_GOTNTPOFF) .Case("gotntpoff", VK_GOTNTPOFF) .Case("PLT", VK_PLT) .Case("plt", VK_PLT) .Case("TLSGD", VK_TLSGD) .Case("tlsgd", VK_TLSGD) .Case("TLSLD", VK_TLSLD) .Case("tlsld", VK_TLSLD) .Case("TLSLDM", VK_TLSLDM) .Case("tlsldm", VK_TLSLDM) .Case("TPOFF", VK_TPOFF) .Case("tpoff", VK_TPOFF) .Case("DTPOFF", VK_DTPOFF) .Case("dtpoff", VK_DTPOFF) .Case("TLVP", VK_TLVP) .Case("tlvp", VK_TLVP) .Case("TLVPPAGE", VK_TLVPPAGE) .Case("tlvppage", VK_TLVPPAGE) .Case("TLVPPAGEOFF", VK_TLVPPAGEOFF) .Case("tlvppageoff", VK_TLVPPAGEOFF) .Case("PAGE", VK_PAGE) .Case("page", VK_PAGE) .Case("PAGEOFF", VK_PAGEOFF) .Case("pageoff", VK_PAGEOFF) .Case("GOTPAGE", VK_GOTPAGE) .Case("gotpage", VK_GOTPAGE) .Case("GOTPAGEOFF", VK_GOTPAGEOFF) .Case("gotpageoff", VK_GOTPAGEOFF) .Case("IMGREL", VK_COFF_IMGREL32) .Case("imgrel", VK_COFF_IMGREL32) .Case("SECREL32", VK_SECREL) .Case("secrel32", VK_SECREL) .Case("L", VK_PPC_LO) .Case("l", VK_PPC_LO) .Case("H", VK_PPC_HI) .Case("h", VK_PPC_HI) .Case("HA", VK_PPC_HA) .Case("ha", VK_PPC_HA) .Case("HIGHER", VK_PPC_HIGHER) .Case("higher", VK_PPC_HIGHER) .Case("HIGHERA", VK_PPC_HIGHERA) .Case("highera", VK_PPC_HIGHERA) .Case("HIGHEST", VK_PPC_HIGHEST) .Case("highest", VK_PPC_HIGHEST) .Case("HIGHESTA", VK_PPC_HIGHESTA) .Case("highesta", VK_PPC_HIGHESTA) .Case("GOT@L", VK_PPC_GOT_LO) .Case("got@l", VK_PPC_GOT_LO) .Case("GOT@H", VK_PPC_GOT_HI) .Case("got@h", VK_PPC_GOT_HI) .Case("GOT@HA", VK_PPC_GOT_HA) .Case("got@ha", VK_PPC_GOT_HA) .Case("TOCBASE", VK_PPC_TOCBASE) .Case("tocbase", VK_PPC_TOCBASE) .Case("TOC", VK_PPC_TOC) .Case("toc", VK_PPC_TOC) .Case("TOC@L", VK_PPC_TOC_LO) .Case("toc@l", VK_PPC_TOC_LO) .Case("TOC@H", VK_PPC_TOC_HI) .Case("toc@h", VK_PPC_TOC_HI) .Case("TOC@HA", VK_PPC_TOC_HA) .Case("toc@ha", VK_PPC_TOC_HA) .Case("TLS", VK_PPC_TLS) .Case("tls", VK_PPC_TLS) .Case("DTPMOD", VK_PPC_DTPMOD) .Case("dtpmod", VK_PPC_DTPMOD) .Case("TPREL", VK_PPC_TPREL) .Case("tprel", VK_PPC_TPREL) .Case("TPREL@L", VK_PPC_TPREL_LO) .Case("tprel@l", VK_PPC_TPREL_LO) .Case("TPREL@H", VK_PPC_TPREL_HI) .Case("tprel@h", VK_PPC_TPREL_HI) .Case("TPREL@HA", VK_PPC_TPREL_HA) .Case("tprel@ha", VK_PPC_TPREL_HA) .Case("TPREL@HIGHER", VK_PPC_TPREL_HIGHER) .Case("tprel@higher", VK_PPC_TPREL_HIGHER) .Case("TPREL@HIGHERA", VK_PPC_TPREL_HIGHERA) .Case("tprel@highera", VK_PPC_TPREL_HIGHERA) .Case("TPREL@HIGHEST", VK_PPC_TPREL_HIGHEST) .Case("tprel@highest", VK_PPC_TPREL_HIGHEST) .Case("TPREL@HIGHESTA", VK_PPC_TPREL_HIGHESTA) .Case("tprel@highesta", VK_PPC_TPREL_HIGHESTA) .Case("DTPREL", VK_PPC_DTPREL) .Case("dtprel", VK_PPC_DTPREL) .Case("DTPREL@L", VK_PPC_DTPREL_LO) .Case("dtprel@l", VK_PPC_DTPREL_LO) .Case("DTPREL@H", VK_PPC_DTPREL_HI) .Case("dtprel@h", VK_PPC_DTPREL_HI) .Case("DTPREL@HA", VK_PPC_DTPREL_HA) .Case("dtprel@ha", VK_PPC_DTPREL_HA) .Case("DTPREL@HIGHER", VK_PPC_DTPREL_HIGHER) .Case("dtprel@higher", VK_PPC_DTPREL_HIGHER) .Case("DTPREL@HIGHERA", VK_PPC_DTPREL_HIGHERA) .Case("dtprel@highera", VK_PPC_DTPREL_HIGHERA) .Case("DTPREL@HIGHEST", VK_PPC_DTPREL_HIGHEST) .Case("dtprel@highest", VK_PPC_DTPREL_HIGHEST) .Case("DTPREL@HIGHESTA", VK_PPC_DTPREL_HIGHESTA) .Case("dtprel@highesta", VK_PPC_DTPREL_HIGHESTA) .Case("GOT@TPREL", VK_PPC_GOT_TPREL) .Case("got@tprel", VK_PPC_GOT_TPREL) .Case("GOT@TPREL@L", VK_PPC_GOT_TPREL_LO) .Case("got@tprel@l", VK_PPC_GOT_TPREL_LO) .Case("GOT@TPREL@H", VK_PPC_GOT_TPREL_HI) .Case("got@tprel@h", VK_PPC_GOT_TPREL_HI) .Case("GOT@TPREL@HA", VK_PPC_GOT_TPREL_HA) .Case("got@tprel@ha", VK_PPC_GOT_TPREL_HA) .Case("GOT@DTPREL", VK_PPC_GOT_DTPREL) .Case("got@dtprel", VK_PPC_GOT_DTPREL) .Case("GOT@DTPREL@L", VK_PPC_GOT_DTPREL_LO) .Case("got@dtprel@l", VK_PPC_GOT_DTPREL_LO) .Case("GOT@DTPREL@H", VK_PPC_GOT_DTPREL_HI) .Case("got@dtprel@h", VK_PPC_GOT_DTPREL_HI) .Case("GOT@DTPREL@HA", VK_PPC_GOT_DTPREL_HA) .Case("got@dtprel@ha", VK_PPC_GOT_DTPREL_HA) .Case("GOT@TLSGD", VK_PPC_GOT_TLSGD) .Case("got@tlsgd", VK_PPC_GOT_TLSGD) .Case("GOT@TLSGD@L", VK_PPC_GOT_TLSGD_LO) .Case("got@tlsgd@l", VK_PPC_GOT_TLSGD_LO) .Case("GOT@TLSGD@H", VK_PPC_GOT_TLSGD_HI) .Case("got@tlsgd@h", VK_PPC_GOT_TLSGD_HI) .Case("GOT@TLSGD@HA", VK_PPC_GOT_TLSGD_HA) .Case("got@tlsgd@ha", VK_PPC_GOT_TLSGD_HA) .Case("GOT@TLSLD", VK_PPC_GOT_TLSLD) .Case("got@tlsld", VK_PPC_GOT_TLSLD) .Case("GOT@TLSLD@L", VK_PPC_GOT_TLSLD_LO) .Case("got@tlsld@l", VK_PPC_GOT_TLSLD_LO) .Case("GOT@TLSLD@H", VK_PPC_GOT_TLSLD_HI) .Case("got@tlsld@h", VK_PPC_GOT_TLSLD_HI) .Case("GOT@TLSLD@HA", VK_PPC_GOT_TLSLD_HA) .Case("got@tlsld@ha", VK_PPC_GOT_TLSLD_HA) .Case("NONE", VK_ARM_NONE) .Case("none", VK_ARM_NONE) .Case("TARGET1", VK_ARM_TARGET1) .Case("target1", VK_ARM_TARGET1) .Case("TARGET2", VK_ARM_TARGET2) .Case("target2", VK_ARM_TARGET2) .Case("PREL31", VK_ARM_PREL31) .Case("prel31", VK_ARM_PREL31) .Case("TLSLDO", VK_ARM_TLSLDO) .Case("tlsldo", VK_ARM_TLSLDO) .Case("TLSCALL", VK_ARM_TLSCALL) .Case("tlscall", VK_ARM_TLSCALL) .Case("TLSDESC", VK_ARM_TLSDESC) .Case("tlsdesc", VK_ARM_TLSDESC) .Default(VK_Invalid); } /* *** */ void MCTargetExpr::anchor() {} /* *** */ bool MCExpr::EvaluateAsAbsolute(int64_t &Res) const { return EvaluateAsAbsolute(Res, nullptr, nullptr, nullptr); } bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAsmLayout &Layout) const { return EvaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr); } bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAsmLayout &Layout, const SectionAddrMap &Addrs) const { return EvaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, &Addrs); } bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const { return EvaluateAsAbsolute(Res, &Asm, nullptr, nullptr); } bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm, const MCAsmLayout *Layout, const SectionAddrMap *Addrs) const { MCValue Value; // Fast path constants. if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(this)) { Res = CE->getValue(); return true; } // FIXME: The use if InSet = Addrs is a hack. Setting InSet causes us // absolutize differences across sections and that is what the MachO writer // uses Addrs for. bool IsRelocatable = EvaluateAsRelocatableImpl(Value, Asm, Layout, Addrs, /*InSet*/ Addrs, /*ForceVarExpansion*/ false); // Record the current value. Res = Value.getConstant(); return IsRelocatable && Value.isAbsolute(); } /// \brief Helper method for \see EvaluateSymbolAdd(). static void AttemptToFoldSymbolOffsetDifference(const MCAssembler *Asm, const MCAsmLayout *Layout, const SectionAddrMap *Addrs, bool InSet, const MCSymbolRefExpr *&A, const MCSymbolRefExpr *&B, int64_t &Addend) { if (!A || !B) return; const MCSymbol &SA = A->getSymbol(); const MCSymbol &SB = B->getSymbol(); if (SA.isUndefined() || SB.isUndefined()) return; if (!Asm->getWriter().IsSymbolRefDifferenceFullyResolved(*Asm, A, B, InSet)) return; const MCSymbolData &AD = Asm->getSymbolData(SA); const MCSymbolData &BD = Asm->getSymbolData(SB); if (AD.getFragment() == BD.getFragment()) { Addend += (AD.getOffset() - BD.getOffset()); // Pointers to Thumb symbols need to have their low-bit set to allow // for interworking. if (Asm->isThumbFunc(&SA)) Addend |= 1; // Clear the symbol expr pointers to indicate we have folded these // operands. A = B = nullptr; return; } if (!Layout) return; const MCSectionData &SecA = *AD.getFragment()->getParent(); const MCSectionData &SecB = *BD.getFragment()->getParent(); if ((&SecA != &SecB) && !Addrs) return; // Eagerly evaluate. Addend += (Layout->getSymbolOffset(&Asm->getSymbolData(A->getSymbol())) - Layout->getSymbolOffset(&Asm->getSymbolData(B->getSymbol()))); if (Addrs && (&SecA != &SecB)) Addend += (Addrs->lookup(&SecA) - Addrs->lookup(&SecB)); // Pointers to Thumb symbols need to have their low-bit set to allow // for interworking. if (Asm->isThumbFunc(&SA)) Addend |= 1; // Clear the symbol expr pointers to indicate we have folded these // operands. A = B = nullptr; } /// \brief Evaluate the result of an add between (conceptually) two MCValues. /// /// This routine conceptually attempts to construct an MCValue: /// Result = (Result_A - Result_B + Result_Cst) /// from two MCValue's LHS and RHS where /// Result = LHS + RHS /// and /// Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst). /// /// This routine attempts to aggresively fold the operands such that the result /// is representable in an MCValue, but may not always succeed. /// /// \returns True on success, false if the result is not representable in an /// MCValue. /// NOTE: It is really important to have both the Asm and Layout arguments. /// They might look redundant, but this function can be used before layout /// is done (see the object streamer for example) and having the Asm argument /// lets us avoid relaxations early. static bool EvaluateSymbolicAdd(const MCAssembler *Asm, const MCAsmLayout *Layout, const SectionAddrMap *Addrs, bool InSet, const MCValue &LHS,const MCSymbolRefExpr *RHS_A, const MCSymbolRefExpr *RHS_B, int64_t RHS_Cst, MCValue &Res) { // FIXME: This routine (and other evaluation parts) are *incredibly* sloppy // about dealing with modifiers. This will ultimately bite us, one day. const MCSymbolRefExpr *LHS_A = LHS.getSymA(); const MCSymbolRefExpr *LHS_B = LHS.getSymB(); int64_t LHS_Cst = LHS.getConstant(); // Fold the result constant immediately. int64_t Result_Cst = LHS_Cst + RHS_Cst; assert((!Layout || Asm) && "Must have an assembler object if layout is given!"); // If we have a layout, we can fold resolved differences. if (Asm) { // First, fold out any differences which are fully resolved. By // reassociating terms in // Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst). // we have the four possible differences: // (LHS_A - LHS_B), // (LHS_A - RHS_B), // (RHS_A - LHS_B), // (RHS_A - RHS_B). // Since we are attempting to be as aggressive as possible about folding, we // attempt to evaluate each possible alternative. AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, LHS_B, Result_Cst); AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, RHS_B, Result_Cst); AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, LHS_B, Result_Cst); AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, RHS_B, Result_Cst); } // We can't represent the addition or subtraction of two symbols. if ((LHS_A && RHS_A) || (LHS_B && RHS_B)) return false; // At this point, we have at most one additive symbol and one subtractive // symbol -- find them. const MCSymbolRefExpr *A = LHS_A ? LHS_A : RHS_A; const MCSymbolRefExpr *B = LHS_B ? LHS_B : RHS_B; // If we have a negated symbol, then we must have also have a non-negated // symbol in order to encode the expression. if (B && !A) return false; Res = MCValue::get(A, B, Result_Cst); return true; } bool MCExpr::EvaluateAsRelocatable(MCValue &Res, const MCAsmLayout *Layout) const { MCAssembler *Assembler = Layout ? &Layout->getAssembler() : nullptr; return EvaluateAsRelocatableImpl(Res, Assembler, Layout, nullptr, false, /*ForceVarExpansion*/ false); } bool MCExpr::EvaluateAsValue(MCValue &Res, const MCAsmLayout *Layout) const { MCAssembler *Assembler = Layout ? &Layout->getAssembler() : nullptr; return EvaluateAsRelocatableImpl(Res, Assembler, Layout, nullptr, false, /*ForceVarExpansion*/ true); } bool MCExpr::EvaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm, const MCAsmLayout *Layout, const SectionAddrMap *Addrs, bool InSet, bool ForceVarExpansion) const { ++stats::MCExprEvaluate; switch (getKind()) { case Target: return cast<MCTargetExpr>(this)->EvaluateAsRelocatableImpl(Res, Layout); case Constant: Res = MCValue::get(cast<MCConstantExpr>(this)->getValue()); return true; case SymbolRef: { const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this); const MCSymbol &Sym = SRE->getSymbol(); const MCAsmInfo &MCAsmInfo = SRE->getMCAsmInfo(); // Evaluate recursively if this is a variable. if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None) { if (Sym.getVariableValue()->EvaluateAsRelocatableImpl( Res, Asm, Layout, Addrs, true, ForceVarExpansion)) { const MCSymbolRefExpr *A = Res.getSymA(); const MCSymbolRefExpr *B = Res.getSymB(); if (MCAsmInfo.hasSubsectionsViaSymbols()) { // FIXME: This is small hack. Given // a = b + 4 // .long a // the OS X assembler will completely drop the 4. We should probably // include it in the relocation or produce an error if that is not // possible. if (!A && !B) return true; } else { if (ForceVarExpansion) return true; bool IsSymbol = A && A->getSymbol().isDefined(); if (!IsSymbol) return true; } } } Res = MCValue::get(SRE, nullptr, 0); return true; } case Unary: { const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this); MCValue Value; if (!AUE->getSubExpr()->EvaluateAsRelocatableImpl(Value, Asm, Layout, Addrs, InSet, ForceVarExpansion)) return false; switch (AUE->getOpcode()) { case MCUnaryExpr::LNot: if (!Value.isAbsolute()) return false; Res = MCValue::get(!Value.getConstant()); break; case MCUnaryExpr::Minus: /// -(a - b + const) ==> (b - a - const) if (Value.getSymA() && !Value.getSymB()) return false; Res = MCValue::get(Value.getSymB(), Value.getSymA(), -Value.getConstant()); break; case MCUnaryExpr::Not: if (!Value.isAbsolute()) return false; Res = MCValue::get(~Value.getConstant()); break; case MCUnaryExpr::Plus: Res = Value; break; } return true; } case Binary: { const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this); MCValue LHSValue, RHSValue; if (!ABE->getLHS()->EvaluateAsRelocatableImpl(LHSValue, Asm, Layout, Addrs, InSet, ForceVarExpansion) || !ABE->getRHS()->EvaluateAsRelocatableImpl(RHSValue, Asm, Layout, Addrs, InSet, ForceVarExpansion)) return false; // We only support a few operations on non-constant expressions, handle // those first. if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) { switch (ABE->getOpcode()) { default: return false; case MCBinaryExpr::Sub: // Negate RHS and add. return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue, RHSValue.getSymB(), RHSValue.getSymA(), -RHSValue.getConstant(), Res); case MCBinaryExpr::Add: return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue, RHSValue.getSymA(), RHSValue.getSymB(), RHSValue.getConstant(), Res); } } // FIXME: We need target hooks for the evaluation. It may be limited in // width, and gas defines the result of comparisons and right shifts // differently from Apple as. int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant(); int64_t Result = 0; switch (ABE->getOpcode()) { case MCBinaryExpr::Add: Result = LHS + RHS; break; case MCBinaryExpr::And: Result = LHS & RHS; break; case MCBinaryExpr::Div: Result = LHS / RHS; break; case MCBinaryExpr::EQ: Result = LHS == RHS; break; case MCBinaryExpr::GT: Result = LHS > RHS; break; case MCBinaryExpr::GTE: Result = LHS >= RHS; break; case MCBinaryExpr::LAnd: Result = LHS && RHS; break; case MCBinaryExpr::LOr: Result = LHS || RHS; break; case MCBinaryExpr::LT: Result = LHS < RHS; break; case MCBinaryExpr::LTE: Result = LHS <= RHS; break; case MCBinaryExpr::Mod: Result = LHS % RHS; break; case MCBinaryExpr::Mul: Result = LHS * RHS; break; case MCBinaryExpr::NE: Result = LHS != RHS; break; case MCBinaryExpr::Or: Result = LHS | RHS; break; case MCBinaryExpr::Shl: Result = LHS << RHS; break; case MCBinaryExpr::Shr: Result = LHS >> RHS; break; case MCBinaryExpr::Sub: Result = LHS - RHS; break; case MCBinaryExpr::Xor: Result = LHS ^ RHS; break; } Res = MCValue::get(Result); return true; } } llvm_unreachable("Invalid assembly expression kind!"); } const MCSection *MCExpr::FindAssociatedSection() const { switch (getKind()) { case Target: // We never look through target specific expressions. return cast<MCTargetExpr>(this)->FindAssociatedSection(); case Constant: return MCSymbol::AbsolutePseudoSection; case SymbolRef: { const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this); const MCSymbol &Sym = SRE->getSymbol(); if (Sym.isDefined()) return &Sym.getSection(); return nullptr; } case Unary: return cast<MCUnaryExpr>(this)->getSubExpr()->FindAssociatedSection(); case Binary: { const MCBinaryExpr *BE = cast<MCBinaryExpr>(this); const MCSection *LHS_S = BE->getLHS()->FindAssociatedSection(); const MCSection *RHS_S = BE->getRHS()->FindAssociatedSection(); // If either section is absolute, return the other. if (LHS_S == MCSymbol::AbsolutePseudoSection) return RHS_S; if (RHS_S == MCSymbol::AbsolutePseudoSection) return LHS_S; // Otherwise, return the first non-null section. return LHS_S ? LHS_S : RHS_S; } } llvm_unreachable("Invalid assembly expression kind!"); }