1 //===- MCAsmLayout.h - Assembly Layout Object -------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #ifndef LLVM_MC_MCASMLAYOUT_H
11 #define LLVM_MC_MCASMLAYOUT_H
13 #include "llvm/ADT/DenseMap.h"
14 #include "llvm/ADT/SmallVector.h"
22 /// Encapsulates the layout of an assembly file at a particular point in time.
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.
30 MCAssembler &Assembler;
32 /// List of sections in layout order.
33 llvm::SmallVector<MCSection *, 16> SectionOrder;
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;
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;
44 /// \brief Is the layout for this fragment valid?
45 bool isFragmentValid(const MCFragment *F) const;
48 MCAsmLayout(MCAssembler &Assembler);
50 /// Get the assembler object this is a layout for.
51 MCAssembler &getAssembler() const { return Assembler; }
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);
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
61 void layoutFragment(MCFragment *Fragment);
63 /// \name Section Access (in layout order)
66 llvm::SmallVectorImpl<MCSection *> &getSectionOrder() { return SectionOrder; }
67 const llvm::SmallVectorImpl<MCSection *> &getSectionOrder() const {
72 /// \name Fragment Layout Data
75 /// \brief Get the offset of the given fragment inside its containing section.
76 uint64_t getFragmentOffset(const MCFragment *F) const;
79 /// \name Utility Functions
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;
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;
91 /// \brief Get the offset of the given symbol, as computed in the current
93 /// \return True on success.
94 bool getSymbolOffset(const MCSymbol &S, uint64_t &Val) const;
96 /// \brief Variant that reports a fatal error if the offset is not computable.
97 uint64_t getSymbolOffset(const MCSymbol &S) const;
99 /// \brief If this symbol is equivalent to A + Constant, return A.
100 const MCSymbol *getBaseSymbol(const MCSymbol &Symbol) const;
105 } // end namespace llvm