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