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Diffstat (limited to 'contrib/llvm/lib/MC/MCExpr.cpp')
| -rw-r--r-- | contrib/llvm/lib/MC/MCExpr.cpp | 819 |
1 files changed, 819 insertions, 0 deletions
diff --git a/contrib/llvm/lib/MC/MCExpr.cpp b/contrib/llvm/lib/MC/MCExpr.cpp new file mode 100644 index 0000000..0f26b38 --- /dev/null +++ b/contrib/llvm/lib/MC/MCExpr.cpp @@ -0,0 +1,819 @@ +//===- 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 MCAsmInfo *MAI) const { + switch (getKind()) { + case MCExpr::Target: + return cast<MCTargetExpr>(this)->printImpl(OS, MAI); + 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().size() && Sym.getName()[0] == '$'; + if (UseParens) { + OS << '('; + Sym.print(OS, MAI); + OS << ')'; + } else + Sym.print(OS, MAI); + + if (SRE.getKind() != MCSymbolRefExpr::VK_None) + SRE.printVariantKind(OS); + + 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; + } + UE.getSubExpr()->print(OS, MAI); + 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())) { + BE.getLHS()->print(OS, MAI); + } else { + OS << '('; + BE.getLHS()->print(OS, MAI); + OS << ')'; + } + + 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::AShr: 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::LShr: 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::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())) { + BE.getRHS()->print(OS, MAI); + } else { + OS << '('; + BE.getRHS()->print(OS, MAI); + OS << ')'; + } + return; + } + } + + llvm_unreachable("Invalid expression kind!"); +} + +#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) +void MCExpr::dump() const { + dbgs() << *this; + 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); +} + +/* *** */ + +MCSymbolRefExpr::MCSymbolRefExpr(const MCSymbol *Symbol, VariantKind Kind, + const MCAsmInfo *MAI) + : MCExpr(MCExpr::SymbolRef), Kind(Kind), + UseParensForSymbolVariant(MAI->useParensForSymbolVariant()), + HasSubsectionsViaSymbols(MAI->hasSubsectionsViaSymbols()), + Symbol(Symbol) { + assert(Symbol); +} + +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_SIZE: return "SIZE"; + case VK_WEAKREF: return "WEAKREF"; + case VK_ARM_NONE: return "none"; + case VK_ARM_GOT_PREL: return "GOT_PREL"; + case VK_ARM_TARGET1: return "target1"; + case VK_ARM_TARGET2: return "target2"; + case VK_ARM_PREL31: return "prel31"; + case VK_ARM_SBREL: return "sbrel"; + 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_PPC_LOCAL: return "local"; + 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_Mips_PCREL_HI16: return "PCREL_HI16"; + case VK_Mips_PCREL_LO16: return "PCREL_LO16"; + case VK_COFF_IMGREL32: return "IMGREL"; + case VK_Hexagon_PCREL: return "PCREL"; + case VK_Hexagon_LO16: return "LO16"; + case VK_Hexagon_HI16: return "HI16"; + case VK_Hexagon_GPREL: return "GPREL"; + case VK_Hexagon_GD_GOT: return "GDGOT"; + case VK_Hexagon_LD_GOT: return "LDGOT"; + case VK_Hexagon_GD_PLT: return "GDPLT"; + case VK_Hexagon_LD_PLT: return "LDPLT"; + case VK_Hexagon_IE: return "IE"; + case VK_Hexagon_IE_GOT: return "IEGOT"; + case VK_TPREL: return "tprel"; + case VK_DTPREL: return "dtprel"; + } + llvm_unreachable("Invalid variant kind"); +} + +MCSymbolRefExpr::VariantKind +MCSymbolRefExpr::getVariantKindForName(StringRef Name) { + return StringSwitch<VariantKind>(Name.lower()) + .Case("got", VK_GOT) + .Case("gotoff", VK_GOTOFF) + .Case("gotpcrel", VK_GOTPCREL) + .Case("gottpoff", VK_GOTTPOFF) + .Case("indntpoff", VK_INDNTPOFF) + .Case("ntpoff", VK_NTPOFF) + .Case("gotntpoff", VK_GOTNTPOFF) + .Case("plt", VK_PLT) + .Case("tlsgd", VK_TLSGD) + .Case("tlsld", VK_TLSLD) + .Case("tlsldm", VK_TLSLDM) + .Case("tpoff", VK_TPOFF) + .Case("dtpoff", VK_DTPOFF) + .Case("tlvp", VK_TLVP) + .Case("tlvppage", VK_TLVPPAGE) + .Case("tlvppageoff", VK_TLVPPAGEOFF) + .Case("page", VK_PAGE) + .Case("pageoff", VK_PAGEOFF) + .Case("gotpage", VK_GOTPAGE) + .Case("gotpageoff", VK_GOTPAGEOFF) + .Case("imgrel", VK_COFF_IMGREL32) + .Case("secrel32", VK_SECREL) + .Case("size", VK_SIZE) + .Case("l", VK_PPC_LO) + .Case("h", VK_PPC_HI) + .Case("ha", VK_PPC_HA) + .Case("higher", VK_PPC_HIGHER) + .Case("highera", VK_PPC_HIGHERA) + .Case("highest", VK_PPC_HIGHEST) + .Case("highesta", VK_PPC_HIGHESTA) + .Case("got@l", VK_PPC_GOT_LO) + .Case("got@h", VK_PPC_GOT_HI) + .Case("got@ha", VK_PPC_GOT_HA) + .Case("local", VK_PPC_LOCAL) + .Case("tocbase", VK_PPC_TOCBASE) + .Case("toc", VK_PPC_TOC) + .Case("toc@l", VK_PPC_TOC_LO) + .Case("toc@h", VK_PPC_TOC_HI) + .Case("toc@ha", VK_PPC_TOC_HA) + .Case("tls", VK_PPC_TLS) + .Case("dtpmod", VK_PPC_DTPMOD) + .Case("tprel", VK_PPC_TPREL) + .Case("tprel@l", VK_PPC_TPREL_LO) + .Case("tprel@h", VK_PPC_TPREL_HI) + .Case("tprel@ha", VK_PPC_TPREL_HA) + .Case("tprel@higher", VK_PPC_TPREL_HIGHER) + .Case("tprel@highera", VK_PPC_TPREL_HIGHERA) + .Case("tprel@highest", VK_PPC_TPREL_HIGHEST) + .Case("tprel@highesta", VK_PPC_TPREL_HIGHESTA) + .Case("dtprel", VK_PPC_DTPREL) + .Case("dtprel@l", VK_PPC_DTPREL_LO) + .Case("dtprel@h", VK_PPC_DTPREL_HI) + .Case("dtprel@ha", VK_PPC_DTPREL_HA) + .Case("dtprel@higher", VK_PPC_DTPREL_HIGHER) + .Case("dtprel@highera", VK_PPC_DTPREL_HIGHERA) + .Case("dtprel@highest", VK_PPC_DTPREL_HIGHEST) + .Case("dtprel@highesta", VK_PPC_DTPREL_HIGHESTA) + .Case("got@tprel", VK_PPC_GOT_TPREL) + .Case("got@tprel@l", VK_PPC_GOT_TPREL_LO) + .Case("got@tprel@h", VK_PPC_GOT_TPREL_HI) + .Case("got@tprel@ha", VK_PPC_GOT_TPREL_HA) + .Case("got@dtprel", VK_PPC_GOT_DTPREL) + .Case("got@dtprel@l", VK_PPC_GOT_DTPREL_LO) + .Case("got@dtprel@h", VK_PPC_GOT_DTPREL_HI) + .Case("got@dtprel@ha", VK_PPC_GOT_DTPREL_HA) + .Case("got@tlsgd", VK_PPC_GOT_TLSGD) + .Case("got@tlsgd@l", VK_PPC_GOT_TLSGD_LO) + .Case("got@tlsgd@h", VK_PPC_GOT_TLSGD_HI) + .Case("got@tlsgd@ha", VK_PPC_GOT_TLSGD_HA) + .Case("got@tlsld", VK_PPC_GOT_TLSLD) + .Case("got@tlsld@l", VK_PPC_GOT_TLSLD_LO) + .Case("got@tlsld@h", VK_PPC_GOT_TLSLD_HI) + .Case("got@tlsld@ha", VK_PPC_GOT_TLSLD_HA) + .Case("gdgot", VK_Hexagon_GD_GOT) + .Case("gdplt", VK_Hexagon_GD_PLT) + .Case("iegot", VK_Hexagon_IE_GOT) + .Case("ie", VK_Hexagon_IE) + .Case("ldgot", VK_Hexagon_LD_GOT) + .Case("ldplt", VK_Hexagon_LD_PLT) + .Case("pcrel", VK_Hexagon_PCREL) + .Case("none", VK_ARM_NONE) + .Case("got_prel", VK_ARM_GOT_PREL) + .Case("target1", VK_ARM_TARGET1) + .Case("target2", VK_ARM_TARGET2) + .Case("prel31", VK_ARM_PREL31) + .Case("sbrel", VK_ARM_SBREL) + .Case("tlsldo", VK_ARM_TLSLDO) + .Case("tlscall", VK_ARM_TLSCALL) + .Case("tlsdesc", VK_ARM_TLSDESC) + .Default(VK_Invalid); +} + +void MCSymbolRefExpr::printVariantKind(raw_ostream &OS) const { + if (UseParensForSymbolVariant) + OS << '(' << MCSymbolRefExpr::getVariantKindName(getKind()) << ')'; + else + OS << '@' << MCSymbolRefExpr::getVariantKindName(getKind()); +} + +/* *** */ + +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::evaluateKnownAbsolute(int64_t &Res, + const MCAsmLayout &Layout) const { + return evaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, nullptr, + true); +} + +bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm, + const MCAsmLayout *Layout, + const SectionAddrMap *Addrs) const { + // 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. + return evaluateAsAbsolute(Res, Asm, Layout, Addrs, Addrs); +} + +bool MCExpr::evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm, + const MCAsmLayout *Layout, + const SectionAddrMap *Addrs, bool InSet) const { + MCValue Value; + + // Fast path constants. + if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(this)) { + Res = CE->getValue(); + return true; + } + + bool IsRelocatable = + evaluateAsRelocatableImpl(Value, Asm, Layout, nullptr, Addrs, InSet); + + // 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; + + if (SA.getFragment() == SB.getFragment() && !SA.isVariable() && + !SB.isVariable()) { + Addend += (SA.getOffset() - SB.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 MCSection &SecA = *SA.getFragment()->getParent(); + const MCSection &SecB = *SB.getFragment()->getParent(); + + if ((&SecA != &SecB) && !Addrs) + return; + + // Eagerly evaluate. + Addend += Layout->getSymbolOffset(A->getSymbol()) - + Layout->getSymbolOffset(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; + + Res = MCValue::get(A, B, Result_Cst); + return true; +} + +bool MCExpr::evaluateAsRelocatable(MCValue &Res, + const MCAsmLayout *Layout, + const MCFixup *Fixup) const { + MCAssembler *Assembler = Layout ? &Layout->getAssembler() : nullptr; + return evaluateAsRelocatableImpl(Res, Assembler, Layout, Fixup, nullptr, + false); +} + +bool MCExpr::evaluateAsValue(MCValue &Res, const MCAsmLayout &Layout) const { + MCAssembler *Assembler = &Layout.getAssembler(); + return evaluateAsRelocatableImpl(Res, Assembler, &Layout, nullptr, nullptr, + true); +} + +static bool canExpand(const MCSymbol &Sym, bool InSet) { + const MCExpr *Expr = Sym.getVariableValue(); + const auto *Inner = dyn_cast<MCSymbolRefExpr>(Expr); + if (Inner) { + if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF) + return false; + } + + if (InSet) + return true; + return !Sym.isInSection(); +} + +bool MCExpr::evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm, + const MCAsmLayout *Layout, + const MCFixup *Fixup, + const SectionAddrMap *Addrs, + bool InSet) const { + ++stats::MCExprEvaluate; + + switch (getKind()) { + case Target: + return cast<MCTargetExpr>(this)->evaluateAsRelocatableImpl(Res, Layout, + Fixup); + + case Constant: + Res = MCValue::get(cast<MCConstantExpr>(this)->getValue()); + return true; + + case SymbolRef: { + const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this); + const MCSymbol &Sym = SRE->getSymbol(); + + // Evaluate recursively if this is a variable. + if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None && + canExpand(Sym, InSet)) { + bool IsMachO = SRE->hasSubsectionsViaSymbols(); + if (Sym.getVariableValue()->evaluateAsRelocatableImpl( + Res, Asm, Layout, Fixup, Addrs, InSet || IsMachO)) { + if (!IsMachO) + return true; + + const MCSymbolRefExpr *A = Res.getSymA(); + const MCSymbolRefExpr *B = Res.getSymB(); + // 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; + } + } + + 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, Fixup, + Addrs, InSet)) + 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, Fixup, + Addrs, InSet) || + !ABE->getRHS()->evaluateAsRelocatableImpl(RHSValue, Asm, Layout, Fixup, + Addrs, InSet)) + 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 differently from + // Apple as. + int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant(); + int64_t Result = 0; + switch (ABE->getOpcode()) { + case MCBinaryExpr::AShr: Result = LHS >> RHS; break; + case MCBinaryExpr::Add: Result = LHS + RHS; break; + case MCBinaryExpr::And: Result = LHS & RHS; break; + case MCBinaryExpr::Div: + // Handle division by zero. gas just emits a warning and keeps going, + // we try to be stricter. + // FIXME: Currently the caller of this function has no way to understand + // we're bailing out because of 'division by zero'. Therefore, it will + // emit a 'expected relocatable expression' error. It would be nice to + // change this code to emit a better diagnostic. + if (RHS == 0) + return false; + 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::LShr: Result = uint64_t(LHS) >> uint64_t(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 = uint64_t(LHS) << uint64_t(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!"); +} + +MCFragment *MCExpr::findAssociatedFragment() const { + switch (getKind()) { + case Target: + // We never look through target specific expressions. + return cast<MCTargetExpr>(this)->findAssociatedFragment(); + + case Constant: + return MCSymbol::AbsolutePseudoFragment; + + case SymbolRef: { + const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this); + const MCSymbol &Sym = SRE->getSymbol(); + return Sym.getFragment(); + } + + case Unary: + return cast<MCUnaryExpr>(this)->getSubExpr()->findAssociatedFragment(); + + case Binary: { + const MCBinaryExpr *BE = cast<MCBinaryExpr>(this); + MCFragment *LHS_F = BE->getLHS()->findAssociatedFragment(); + MCFragment *RHS_F = BE->getRHS()->findAssociatedFragment(); + + // If either is absolute, return the other. + if (LHS_F == MCSymbol::AbsolutePseudoFragment) + return RHS_F; + if (RHS_F == MCSymbol::AbsolutePseudoFragment) + return LHS_F; + + // Not always correct, but probably the best we can do without more context. + if (BE->getOpcode() == MCBinaryExpr::Sub) + return MCSymbol::AbsolutePseudoFragment; + + // Otherwise, return the first non-null fragment. + return LHS_F ? LHS_F : RHS_F; + } + } + + llvm_unreachable("Invalid assembly expression kind!"); +} |
