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 MCSection; 20 class MCSymbol; 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 MCAssembler &Assembler; 31 32 /// List of sections in layout order. 33 llvm::SmallVector<MCSection *, 16> SectionOrder; 34 35 /// The last fragment which was laid out, or 0 if nothing has been laid 36 /// out. Fragments are always laid out in order, so all fragments with a 37 /// lower ordinal will be valid. 38 mutable DenseMap<const MCSection *, MCFragment *> LastValidFragment; 39 40 /// \brief Make sure that the layout for the given fragment is valid, lazily 41 /// computing it if necessary. 42 void ensureValid(const MCFragment *F) const; 43 44 /// \brief Is the layout for this fragment valid? 45 bool isFragmentValid(const MCFragment *F) const; 46 47 public: 48 MCAsmLayout(MCAssembler &Assembler); 49 50 /// Get the assembler object this is a layout for. 51 MCAssembler &getAssembler() const { return Assembler; } 52 53 /// \brief Invalidate the fragments starting with F because it has been 54 /// resized. The fragment's size should have already been updated, but 55 /// its bundle padding will be recomputed. 56 void invalidateFragmentsFrom(MCFragment *F); 57 58 /// \brief Perform layout for a single fragment, assuming that the previous 59 /// fragment has already been laid out correctly, and the parent section has 60 /// been initialized. 61 void layoutFragment(MCFragment *Fragment); 62 63 /// \name Section Access (in layout order) 64 /// @{ 65 66 llvm::SmallVectorImpl<MCSection *> &getSectionOrder() { return SectionOrder; } 67 const llvm::SmallVectorImpl<MCSection *> &getSectionOrder() const { 68 return SectionOrder; 69 } 70 71 /// @} 72 /// \name Fragment Layout Data 73 /// @{ 74 75 /// \brief Get the offset of the given fragment inside its containing section. 76 uint64_t getFragmentOffset(const MCFragment *F) const; 77 78 /// @} 79 /// \name Utility Functions 80 /// @{ 81 82 /// \brief Get the address space size of the given section, as it effects 83 /// layout. This may differ from the size reported by \see getSectionSize() by 84 /// not including section tail padding. 85 uint64_t getSectionAddressSize(const MCSection *Sec) const; 86 87 /// \brief Get the data size of the given section, as emitted to the object 88 /// file. This may include additional padding, or be 0 for virtual sections. 89 uint64_t getSectionFileSize(const MCSection *Sec) const; 90 91 /// \brief Get the offset of the given symbol, as computed in the current 92 /// layout. 93 /// \return True on success. 94 bool getSymbolOffset(const MCSymbol &S, uint64_t &Val) const; 95 96 /// \brief Variant that reports a fatal error if the offset is not computable. 97 uint64_t getSymbolOffset(const MCSymbol &S) const; 98 99 /// \brief If this symbol is equivalent to A + Constant, return A. 100 const MCSymbol *getBaseSymbol(const MCSymbol &Symbol) const; 101 102 /// @} 103 }; 104 105 } // end namespace llvm 106 107 #endif 108
