1 //===- MCAsmLayout.h - Assembly Layout Object -------------------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef LLVM_MC_MCASMLAYOUT_H 10 #define LLVM_MC_MCASMLAYOUT_H 11 12 #include "llvm/ADT/DenseMap.h" 13 #include "llvm/ADT/SmallVector.h" 14 15 namespace llvm { 16 class MCAssembler; 17 class MCFragment; 18 class MCSection; 19 class MCSymbol; 20 21 /// Encapsulates the layout of an assembly file at a particular point in time. 22 /// 23 /// Assembly may require computing multiple layouts for a particular assembly 24 /// file as part of the relaxation process. This class encapsulates the layout 25 /// at a single point in time in such a way that it is always possible to 26 /// efficiently compute the exact address of any symbol in the assembly file, 27 /// even during the relaxation process. 28 class MCAsmLayout { 29 MCAssembler &Assembler; 30 31 /// List of sections in layout order. 32 llvm::SmallVector<MCSection *, 16> SectionOrder; 33 34 /// The last fragment which was laid out, or 0 if nothing has been laid 35 /// out. Fragments are always laid out in order, so all fragments with a 36 /// lower ordinal will be valid. 37 mutable DenseMap<const MCSection *, MCFragment *> LastValidFragment; 38 39 /// Make sure that the layout for the given fragment is valid, lazily 40 /// computing it if necessary. 41 void ensureValid(const MCFragment *F) const; 42 43 /// Is the layout for this fragment valid? 44 bool isFragmentValid(const MCFragment *F) const; 45 46 public: 47 MCAsmLayout(MCAssembler &Assembler); 48 49 /// Get the assembler object this is a layout for. 50 MCAssembler &getAssembler() const { return Assembler; } 51 52 /// Invalidate the fragments starting with F because it has been 53 /// resized. The fragment's size should have already been updated, but 54 /// its bundle padding will be recomputed. 55 void invalidateFragmentsFrom(MCFragment *F); 56 57 /// Perform layout for a single fragment, assuming that the previous 58 /// fragment has already been laid out correctly, and the parent section has 59 /// been initialized. 60 void layoutFragment(MCFragment *Fragment); 61 62 /// \name Section Access (in layout order) 63 /// @{ 64 65 llvm::SmallVectorImpl<MCSection *> &getSectionOrder() { return SectionOrder; } 66 const llvm::SmallVectorImpl<MCSection *> &getSectionOrder() const { 67 return SectionOrder; 68 } 69 70 /// @} 71 /// \name Fragment Layout Data 72 /// @{ 73 74 /// Get the offset of the given fragment inside its containing section. 75 uint64_t getFragmentOffset(const MCFragment *F) const; 76 77 /// @} 78 /// \name Utility Functions 79 /// @{ 80 81 /// Get the address space size of the given section, as it effects 82 /// layout. This may differ from the size reported by \see getSectionSize() by 83 /// not including section tail padding. 84 uint64_t getSectionAddressSize(const MCSection *Sec) const; 85 86 /// Get the data size of the given section, as emitted to the object 87 /// file. This may include additional padding, or be 0 for virtual sections. 88 uint64_t getSectionFileSize(const MCSection *Sec) const; 89 90 /// Get the offset of the given symbol, as computed in the current 91 /// layout. 92 /// \return True on success. 93 bool getSymbolOffset(const MCSymbol &S, uint64_t &Val) const; 94 95 /// Variant that reports a fatal error if the offset is not computable. 96 uint64_t getSymbolOffset(const MCSymbol &S) const; 97 98 /// If this symbol is equivalent to A + Constant, return A. 99 const MCSymbol *getBaseSymbol(const MCSymbol &Symbol) const; 100 101 /// @} 102 }; 103 104 } // end namespace llvm 105 106 #endif 107