1 //===- MCAsmLayout.h - Assembly Layout Object -------------------*- 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_MCASMLAYOUT_H 11 #define LLVM_MC_MCASMLAYOUT_H 12 13 #include "llvm/ADT/DenseMap.h" 14 #include "llvm/ADT/SmallVector.h" 15 16 namespace llvm { 17 class MCAssembler; 18 class MCFragment; 19 class MCSectionData; 20 class MCSymbol; 21 class MCSymbolData; 22 23 /// Encapsulates the layout of an assembly file at a particular point in time. 24 /// 25 /// Assembly may require computing multiple layouts for a particular assembly 26 /// file as part of the relaxation process. This class encapsulates the layout 27 /// at a single point in time in such a way that it is always possible to 28 /// efficiently compute the exact address of any symbol in the assembly file, 29 /// even during the relaxation process. 30 class MCAsmLayout { 31 public: 32 typedef llvm::SmallVectorImpl<MCSectionData*>::const_iterator const_iterator; 33 typedef llvm::SmallVectorImpl<MCSectionData*>::iterator iterator; 34 35 private: 36 MCAssembler &Assembler; 37 38 /// List of sections in layout order. 39 llvm::SmallVector<MCSectionData*, 16> SectionOrder; 40 41 /// The last fragment which was laid out, or 0 if nothing has been laid 42 /// out. Fragments are always laid out in order, so all fragments with a 43 /// lower ordinal will be valid. 44 mutable DenseMap<const MCSectionData*, MCFragment*> LastValidFragment; 45 46 /// \brief Make sure that the layout for the given fragment is valid, lazily 47 /// computing it if necessary. 48 void ensureValid(const MCFragment *F) const; 49 50 /// \brief Is the layout for this fragment valid? 51 bool isFragmentValid(const MCFragment *F) const; 52 53 /// \brief Compute the amount of padding required before this fragment to 54 /// obey bundling restrictions. 55 uint64_t computeBundlePadding(const MCFragment *F, 56 uint64_t FOffset, uint64_t FSize); 57 58 public: 59 MCAsmLayout(MCAssembler &_Assembler); 60 61 /// Get the assembler object this is a layout for. 62 MCAssembler &getAssembler() const { return Assembler; } 63 64 /// \brief Invalidate the fragments starting with F because it has been 65 /// resized. The fragment's size should have already been updated, but 66 /// its bundle padding will be recomputed. 67 void invalidateFragmentsFrom(MCFragment *F); 68 69 /// \brief Perform layout for a single fragment, assuming that the previous 70 /// fragment has already been laid out correctly, and the parent section has 71 /// been initialized. 72 void layoutFragment(MCFragment *Fragment); 73 74 /// @name Section Access (in layout order) 75 /// @{ 76 77 llvm::SmallVectorImpl<MCSectionData*> &getSectionOrder() { 78 return SectionOrder; 79 } 80 const llvm::SmallVectorImpl<MCSectionData*> &getSectionOrder() const { 81 return SectionOrder; 82 } 83 84 /// @} 85 /// @name Fragment Layout Data 86 /// @{ 87 88 /// \brief Get the offset of the given fragment inside its containing section. 89 uint64_t getFragmentOffset(const MCFragment *F) const; 90 91 /// @} 92 /// @name Utility Functions 93 /// @{ 94 95 /// \brief Get the address space size of the given section, as it effects 96 /// layout. This may differ from the size reported by \see getSectionSize() by 97 /// not including section tail padding. 98 uint64_t getSectionAddressSize(const MCSectionData *SD) const; 99 100 /// \brief Get the data size of the given section, as emitted to the object 101 /// file. This may include additional padding, or be 0 for virtual sections. 102 uint64_t getSectionFileSize(const MCSectionData *SD) const; 103 104 /// \brief Get the offset of the given symbol, as computed in the current 105 /// layout. 106 /// \result True on success. 107 bool getSymbolOffset(const MCSymbolData *SD, uint64_t &Val) const; 108 109 /// \brief Variant that reports a fatal error if the offset is not computable. 110 uint64_t getSymbolOffset(const MCSymbolData *SD) const; 111 112 /// \brief If this symbol is equivalent to A + Constant, return A. 113 const MCSymbol *getBaseSymbol(const MCSymbol &Symbol) const; 114 115 /// @} 116 }; 117 118 } // end namespace llvm 119 120 #endif 121
