LCOV - code coverage report
Current view: top level - include/llvm/MC - MCAssembler.h (source / functions) Hit Total Coverage
Test: llvm-toolchain.info Lines: 35 35 100.0 %
Date: 2017-09-14 15:23:50 Functions: 2 2 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : //===- MCAssembler.h - Object File Generation -------------------*- C++ -*-===//
       2             : //
       3             : //                     The LLVM Compiler Infrastructure
       4             : //
       5             : // This file is distributed under the University of Illinois Open Source
       6             : // License. See LICENSE.TXT for details.
       7             : //
       8             : //===----------------------------------------------------------------------===//
       9             : 
      10             : #ifndef LLVM_MC_MCASSEMBLER_H
      11             : #define LLVM_MC_MCASSEMBLER_H
      12             : 
      13             : #include "llvm/ADT/ArrayRef.h"
      14             : #include "llvm/ADT/STLExtras.h"
      15             : #include "llvm/ADT/SmallPtrSet.h"
      16             : #include "llvm/ADT/StringRef.h"
      17             : #include "llvm/ADT/iterator.h"
      18             : #include "llvm/ADT/iterator_range.h"
      19             : #include "llvm/MC/MCDirectives.h"
      20             : #include "llvm/MC/MCDwarf.h"
      21             : #include "llvm/MC/MCFixup.h"
      22             : #include "llvm/MC/MCFragment.h"
      23             : #include "llvm/MC/MCLinkerOptimizationHint.h"
      24             : #include "llvm/MC/MCSymbol.h"
      25             : #include <cassert>
      26             : #include <cstddef>
      27             : #include <cstdint>
      28             : #include <string>
      29             : #include <utility>
      30             : #include <vector>
      31             : 
      32             : namespace llvm {
      33             : 
      34             : class MCAsmBackend;
      35             : class MCAsmLayout;
      36             : class MCContext;
      37             : class MCCodeEmitter;
      38             : class MCFragment;
      39             : class MCObjectWriter;
      40             : class MCSection;
      41             : class MCValue;
      42             : 
      43             : // FIXME: This really doesn't belong here. See comments below.
      44             : struct IndirectSymbolData {
      45             :   MCSymbol *Symbol;
      46             :   MCSection *Section;
      47             : };
      48             : 
      49             : // FIXME: Ditto this. Purely so the Streamer and the ObjectWriter can talk
      50             : // to one another.
      51             : struct DataRegionData {
      52             :   // This enum should be kept in sync w/ the mach-o definition in
      53             :   // llvm/Object/MachOFormat.h.
      54             :   enum KindTy { Data = 1, JumpTable8, JumpTable16, JumpTable32 } Kind;
      55             :   MCSymbol *Start;
      56             :   MCSymbol *End;
      57             : };
      58             : 
      59       28847 : class MCAssembler {
      60             :   friend class MCAsmLayout;
      61             : 
      62             : public:
      63             :   using SectionListType = std::vector<MCSection *>;
      64             :   using SymbolDataListType = std::vector<const MCSymbol *>;
      65             : 
      66             :   using const_iterator = pointee_iterator<SectionListType::const_iterator>;
      67             :   using iterator = pointee_iterator<SectionListType::iterator>;
      68             : 
      69             :   using const_symbol_iterator =
      70             :       pointee_iterator<SymbolDataListType::const_iterator>;
      71             :   using symbol_iterator = pointee_iterator<SymbolDataListType::iterator>;
      72             : 
      73             :   using symbol_range = iterator_range<symbol_iterator>;
      74             :   using const_symbol_range = iterator_range<const_symbol_iterator>;
      75             : 
      76             :   using const_indirect_symbol_iterator =
      77             :       std::vector<IndirectSymbolData>::const_iterator;
      78             :   using indirect_symbol_iterator = std::vector<IndirectSymbolData>::iterator;
      79             : 
      80             :   using const_data_region_iterator =
      81             :       std::vector<DataRegionData>::const_iterator;
      82             :   using data_region_iterator = std::vector<DataRegionData>::iterator;
      83             : 
      84             :   /// MachO specific deployment target version info.
      85             :   // A Major version of 0 indicates that no version information was supplied
      86             :   // and so the corresponding load command should not be emitted.
      87             :   using VersionMinInfoType = struct {
      88             :     MCVersionMinType Kind;
      89             :     unsigned Major;
      90             :     unsigned Minor;
      91             :     unsigned Update;
      92             :   };
      93             : 
      94             : private:
      95             :   MCContext &Context;
      96             : 
      97             :   MCAsmBackend &Backend;
      98             : 
      99             :   MCCodeEmitter &Emitter;
     100             : 
     101             :   MCObjectWriter &Writer;
     102             : 
     103             :   SectionListType Sections;
     104             : 
     105             :   SymbolDataListType Symbols;
     106             : 
     107             :   std::vector<IndirectSymbolData> IndirectSymbols;
     108             : 
     109             :   std::vector<DataRegionData> DataRegions;
     110             : 
     111             :   /// The list of linker options to propagate into the object file.
     112             :   std::vector<std::vector<std::string>> LinkerOptions;
     113             : 
     114             :   /// List of declared file names
     115             :   std::vector<std::string> FileNames;
     116             : 
     117             :   MCDwarfLineTableParams LTParams;
     118             : 
     119             :   /// The set of function symbols for which a .thumb_func directive has
     120             :   /// been seen.
     121             :   //
     122             :   // FIXME: We really would like this in target specific code rather than
     123             :   // here. Maybe when the relocation stuff moves to target specific,
     124             :   // this can go with it? The streamer would need some target specific
     125             :   // refactoring too.
     126             :   mutable SmallPtrSet<const MCSymbol *, 32> ThumbFuncs;
     127             : 
     128             :   /// \brief The bundle alignment size currently set in the assembler.
     129             :   ///
     130             :   /// By default it's 0, which means bundling is disabled.
     131             :   unsigned BundleAlignSize;
     132             : 
     133             :   bool RelaxAll : 1;
     134             :   bool SubsectionsViaSymbols : 1;
     135             :   bool IncrementalLinkerCompatible : 1;
     136             : 
     137             :   /// ELF specific e_header flags
     138             :   // It would be good if there were an MCELFAssembler class to hold this.
     139             :   // ELF header flags are used both by the integrated and standalone assemblers.
     140             :   // Access to the flags is necessary in cases where assembler directives affect
     141             :   // which flags to be set.
     142             :   unsigned ELFHeaderEFlags;
     143             : 
     144             :   /// Used to communicate Linker Optimization Hint information between
     145             :   /// the Streamer and the .o writer
     146             :   MCLOHContainer LOHContainer;
     147             : 
     148             :   VersionMinInfoType VersionMinInfo;
     149             : 
     150             :   /// Evaluate a fixup to a relocatable expression and the value which should be
     151             :   /// placed into the fixup.
     152             :   ///
     153             :   /// \param Layout The layout to use for evaluation.
     154             :   /// \param Fixup The fixup to evaluate.
     155             :   /// \param DF The fragment the fixup is inside.
     156             :   /// \param Target [out] On return, the relocatable expression the fixup
     157             :   /// evaluates to.
     158             :   /// \param Value [out] On return, the value of the fixup as currently laid
     159             :   /// out.
     160             :   /// \return Whether the fixup value was fully resolved. This is true if the
     161             :   /// \p Value result is fixed, otherwise the value may change due to
     162             :   /// relocation.
     163             :   bool evaluateFixup(const MCAsmLayout &Layout, const MCFixup &Fixup,
     164             :                      const MCFragment *DF, MCValue &Target,
     165             :                      uint64_t &Value) const;
     166             : 
     167             :   /// Check whether a fixup can be satisfied, or whether it needs to be relaxed
     168             :   /// (increased in size, in order to hold its value correctly).
     169             :   bool fixupNeedsRelaxation(const MCFixup &Fixup, const MCRelaxableFragment *DF,
     170             :                             const MCAsmLayout &Layout) const;
     171             : 
     172             :   /// Check whether the given fragment needs relaxation.
     173             :   bool fragmentNeedsRelaxation(const MCRelaxableFragment *IF,
     174             :                                const MCAsmLayout &Layout) const;
     175             : 
     176             :   /// \brief Perform one layout iteration and return true if any offsets
     177             :   /// were adjusted.
     178             :   bool layoutOnce(MCAsmLayout &Layout);
     179             : 
     180             :   /// \brief Perform one layout iteration of the given section and return true
     181             :   /// if any offsets were adjusted.
     182             :   bool layoutSectionOnce(MCAsmLayout &Layout, MCSection &Sec);
     183             : 
     184             :   bool relaxInstruction(MCAsmLayout &Layout, MCRelaxableFragment &IF);
     185             : 
     186             :   bool relaxLEB(MCAsmLayout &Layout, MCLEBFragment &IF);
     187             : 
     188             :   bool relaxDwarfLineAddr(MCAsmLayout &Layout, MCDwarfLineAddrFragment &DF);
     189             :   bool relaxDwarfCallFrameFragment(MCAsmLayout &Layout,
     190             :                                    MCDwarfCallFrameFragment &DF);
     191             :   bool relaxCVInlineLineTable(MCAsmLayout &Layout,
     192             :                               MCCVInlineLineTableFragment &DF);
     193             :   bool relaxCVDefRange(MCAsmLayout &Layout, MCCVDefRangeFragment &DF);
     194             : 
     195             :   /// finishLayout - Finalize a layout, including fragment lowering.
     196             :   void finishLayout(MCAsmLayout &Layout);
     197             : 
     198             :   std::tuple<MCValue, uint64_t, bool>
     199             :   handleFixup(const MCAsmLayout &Layout, MCFragment &F, const MCFixup &Fixup);
     200             : 
     201             : public:
     202             :   /// Construct a new assembler instance.
     203             :   //
     204             :   // FIXME: How are we going to parameterize this? Two obvious options are stay
     205             :   // concrete and require clients to pass in a target like object. The other
     206             :   // option is to make this abstract, and have targets provide concrete
     207             :   // implementations as we do with AsmParser.
     208             :   MCAssembler(MCContext &Context, MCAsmBackend &Backend,
     209             :               MCCodeEmitter &Emitter, MCObjectWriter &Writer);
     210             :   MCAssembler(const MCAssembler &) = delete;
     211             :   MCAssembler &operator=(const MCAssembler &) = delete;
     212             :   ~MCAssembler();
     213             : 
     214             :   /// Compute the effective fragment size assuming it is laid out at the given
     215             :   /// \p SectionAddress and \p FragmentOffset.
     216             :   uint64_t computeFragmentSize(const MCAsmLayout &Layout,
     217             :                                const MCFragment &F) const;
     218             : 
     219             :   /// Find the symbol which defines the atom containing the given symbol, or
     220             :   /// null if there is no such symbol.
     221             :   const MCSymbol *getAtom(const MCSymbol &S) const;
     222             : 
     223             :   /// Check whether a particular symbol is visible to the linker and is required
     224             :   /// in the symbol table, or whether it can be discarded by the assembler. This
     225             :   /// also effects whether the assembler treats the label as potentially
     226             :   /// defining a separate atom.
     227             :   bool isSymbolLinkerVisible(const MCSymbol &SD) const;
     228             : 
     229             :   /// Emit the section contents using the given object writer.
     230             :   void writeSectionData(const MCSection *Section,
     231             :                         const MCAsmLayout &Layout) const;
     232             : 
     233             :   /// Check whether a given symbol has been flagged with .thumb_func.
     234             :   bool isThumbFunc(const MCSymbol *Func) const;
     235             : 
     236             :   /// Flag a function symbol as the target of a .thumb_func directive.
     237         684 :   void setIsThumbFunc(const MCSymbol *Func) { ThumbFuncs.insert(Func); }
     238             : 
     239             :   /// ELF e_header flags
     240             :   unsigned getELFHeaderEFlags() const { return ELFHeaderEFlags; }
     241        1939 :   void setELFHeaderEFlags(unsigned Flags) { ELFHeaderEFlags = Flags; }
     242             : 
     243             :   /// MachO deployment target version information.
     244             :   const VersionMinInfoType &getVersionMinInfo() const { return VersionMinInfo; }
     245             :   void setVersionMinInfo(MCVersionMinType Kind, unsigned Major, unsigned Minor,
     246             :                          unsigned Update) {
     247         266 :     VersionMinInfo.Kind = Kind;
     248         266 :     VersionMinInfo.Major = Major;
     249         266 :     VersionMinInfo.Minor = Minor;
     250         266 :     VersionMinInfo.Update = Update;
     251             :   }
     252             : 
     253             :   /// Reuse an assembler instance
     254             :   ///
     255             :   void reset();
     256             : 
     257             :   MCContext &getContext() const { return Context; }
     258             : 
     259             :   MCAsmBackend &getBackend() const { return Backend; }
     260             : 
     261             :   MCCodeEmitter &getEmitter() const { return Emitter; }
     262             : 
     263             :   MCObjectWriter &getWriter() const { return Writer; }
     264             : 
     265      533522 :   MCDwarfLineTableParams getDWARFLinetableParams() const { return LTParams; }
     266             :   void setDWARFLinetableParams(MCDwarfLineTableParams P) { LTParams = P; }
     267             : 
     268             :   /// Finish - Do final processing and write the object to the output stream.
     269             :   /// \p Writer is used for custom object writer (as the MCJIT does),
     270             :   /// if not specified it is automatically created from backend.
     271             :   void Finish();
     272             : 
     273             :   // Layout all section and prepare them for emission.
     274             :   void layout(MCAsmLayout &Layout);
     275             : 
     276             :   // FIXME: This does not belong here.
     277         547 :   bool getSubsectionsViaSymbols() const { return SubsectionsViaSymbols; }
     278         283 :   void setSubsectionsViaSymbols(bool Value) { SubsectionsViaSymbols = Value; }
     279             : 
     280             :   bool isIncrementalLinkerCompatible() const {
     281        2752 :     return IncrementalLinkerCompatible;
     282             :   }
     283             :   void setIncrementalLinkerCompatible(bool Value) {
     284         283 :     IncrementalLinkerCompatible = Value;
     285             :   }
     286             : 
     287      134311 :   bool getRelaxAll() const { return RelaxAll; }
     288         293 :   void setRelaxAll(bool Value) { RelaxAll = Value; }
     289             : 
     290             :   bool isBundlingEnabled() const { return BundleAlignSize != 0; }
     291             : 
     292             :   unsigned getBundleAlignSize() const { return BundleAlignSize; }
     293             : 
     294             :   void setBundleAlignSize(unsigned Size) {
     295             :     assert((Size == 0 || !(Size & (Size - 1))) &&
     296             :            "Expect a power-of-two bundle align size");
     297          38 :     BundleAlignSize = Size;
     298             :   }
     299             : 
     300             :   /// \name Section List Access
     301             :   /// @{
     302             : 
     303       85287 :   iterator begin() { return Sections.begin(); }
     304             :   const_iterator begin() const { return Sections.begin(); }
     305             : 
     306       85287 :   iterator end() { return Sections.end(); }
     307             :   const_iterator end() const { return Sections.end(); }
     308             : 
     309         498 :   size_t size() const { return Sections.size(); }
     310             : 
     311             :   /// @}
     312             :   /// \name Symbol List Access
     313             :   /// @{
     314       26559 :   symbol_iterator symbol_begin() { return Symbols.begin(); }
     315             :   const_symbol_iterator symbol_begin() const { return Symbols.begin(); }
     316             : 
     317       26559 :   symbol_iterator symbol_end() { return Symbols.end(); }
     318             :   const_symbol_iterator symbol_end() const { return Symbols.end(); }
     319             : 
     320       26559 :   symbol_range symbols() { return make_range(symbol_begin(), symbol_end()); }
     321             :   const_symbol_range symbols() const {
     322             :     return make_range(symbol_begin(), symbol_end());
     323             :   }
     324             : 
     325             :   size_t symbol_size() const { return Symbols.size(); }
     326             : 
     327             :   /// @}
     328             :   /// \name Indirect Symbol List Access
     329             :   /// @{
     330             : 
     331             :   // FIXME: This is a total hack, this should not be here. Once things are
     332             :   // factored so that the streamer has direct access to the .o writer, it can
     333             :   // disappear.
     334             :   std::vector<IndirectSymbolData> &getIndirectSymbols() {
     335          41 :     return IndirectSymbols;
     336             :   }
     337             : 
     338             :   indirect_symbol_iterator indirect_symbol_begin() {
     339        2922 :     return IndirectSymbols.begin();
     340             :   }
     341             :   const_indirect_symbol_iterator indirect_symbol_begin() const {
     342             :     return IndirectSymbols.begin();
     343             :   }
     344             : 
     345             :   indirect_symbol_iterator indirect_symbol_end() {
     346        2922 :     return IndirectSymbols.end();
     347             :   }
     348             :   const_indirect_symbol_iterator indirect_symbol_end() const {
     349             :     return IndirectSymbols.end();
     350             :   }
     351             : 
     352         413 :   size_t indirect_symbol_size() const { return IndirectSymbols.size(); }
     353             : 
     354             :   /// @}
     355             :   /// \name Linker Option List Access
     356             :   /// @{
     357             : 
     358             :   std::vector<std::vector<std::string>> &getLinkerOptions() {
     359           5 :     return LinkerOptions;
     360             :   }
     361             : 
     362             :   /// @}
     363             :   /// \name Data Region List Access
     364             :   /// @{
     365             : 
     366             :   // FIXME: This is a total hack, this should not be here. Once things are
     367             :   // factored so that the streamer has direct access to the .o writer, it can
     368             :   // disappear.
     369          47 :   std::vector<DataRegionData> &getDataRegions() { return DataRegions; }
     370             : 
     371         996 :   data_region_iterator data_region_begin() { return DataRegions.begin(); }
     372             :   const_data_region_iterator data_region_begin() const {
     373             :     return DataRegions.begin();
     374             :   }
     375             : 
     376         996 :   data_region_iterator data_region_end() { return DataRegions.end(); }
     377             :   const_data_region_iterator data_region_end() const {
     378             :     return DataRegions.end();
     379             :   }
     380             : 
     381             :   size_t data_region_size() const { return DataRegions.size(); }
     382             : 
     383             :   /// @}
     384             :   /// \name Data Region List Access
     385             :   /// @{
     386             : 
     387             :   // FIXME: This is a total hack, this should not be here. Once things are
     388             :   // factored so that the streamer has direct access to the .o writer, it can
     389             :   // disappear.
     390         499 :   MCLOHContainer &getLOHContainer() { return LOHContainer; }
     391             :   const MCLOHContainer &getLOHContainer() const {
     392             :     return const_cast<MCAssembler *>(this)->getLOHContainer();
     393             :   }
     394             :   /// @}
     395             :   /// \name Backend Data Access
     396             :   /// @{
     397             : 
     398             :   bool registerSection(MCSection &Section);
     399             : 
     400             :   void registerSymbol(const MCSymbol &Symbol, bool *Created = nullptr);
     401             : 
     402        7128 :   ArrayRef<std::string> getFileNames() { return FileNames; }
     403             : 
     404        1225 :   void addFileName(StringRef FileName) {
     405        2449 :     if (!is_contained(FileNames, FileName))
     406        4899 :       FileNames.push_back(FileName);
     407        1225 :   }
     408             : 
     409             :   /// \brief Write the necessary bundle padding to the given object writer.
     410             :   /// Expects a fragment \p F containing instructions and its size \p FSize.
     411             :   void writeFragmentPadding(const MCFragment &F, uint64_t FSize,
     412             :                             MCObjectWriter *OW) const;
     413             : 
     414             :   /// @}
     415             : 
     416             :   void dump() const;
     417             : };
     418             : 
     419             : /// \brief Compute the amount of padding required before the fragment \p F to
     420             : /// obey bundling restrictions, where \p FOffset is the fragment's offset in
     421             : /// its section and \p FSize is the fragment's size.
     422             : uint64_t computeBundlePadding(const MCAssembler &Assembler, const MCFragment *F,
     423             :                               uint64_t FOffset, uint64_t FSize);
     424             : 
     425             : } // end namespace llvm
     426             : 
     427             : #endif // LLVM_MC_MCASSEMBLER_H

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