include/llvm/MC/MCAsmLayout.h

   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