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       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             :   /// 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             :   /// 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           0 :   MCAssembler &getAssembler() const { return Assembler; }
      52             : 
      53             :   /// 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             :   /// 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             :   /// 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             :   /// 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             :   /// 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             :   /// 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             :   /// Variant that reports a fatal error if the offset is not computable.
      97             :   uint64_t getSymbolOffset(const MCSymbol &S) const;
      98             : 
      99             :   /// 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