include/llvm/MC/MCSection.h

   1 //===- MCSection.h - Machine Code Sections ----------------------*- 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 // This file declares the MCSection class.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #ifndef LLVM_MC_MCSECTION_H
  14 #define LLVM_MC_MCSECTION_H
  15
  16 #include "llvm/ADT/SmallVector.h"
  17 #include "llvm/ADT/ilist.h"
  18 #include "llvm/MC/MCFragment.h"
  19 #include "llvm/MC/SectionKind.h"
  20 #include <cassert>
  21 #include <utility>
  22
  23 namespace llvm {
  24
  25 class MCAsmInfo;
  26 class MCContext;
  27 class MCExpr;
  28 class MCSymbol;
  29 class raw_ostream;
  30 class Triple;
  31
  32 template <> struct ilist_alloc_traits<MCFragment> {
  33   static void deleteNode(MCFragment *V);
  34 };
  35
  36 /// Instances of this class represent a uniqued identifier for a section in the
  37 /// current translation unit.  The MCContext class uniques and creates these.
  38 class MCSection {
  39 public:
  40   enum SectionVariant { SV_COFF = 0, SV_ELF, SV_MachO, SV_Wasm, SV_XCOFF };
  41
  42   /// Express the state of bundle locked groups while emitting code.
  43   enum BundleLockStateType {
  44     NotBundleLocked,
  45     BundleLocked,
  46     BundleLockedAlignToEnd
  47   };
  48
  49   using FragmentListType = iplist<MCFragment>;
  50
  51   using const_iterator = FragmentListType::const_iterator;
  52   using iterator = FragmentListType::iterator;
  53
  54   using const_reverse_iterator = FragmentListType::const_reverse_iterator;
  55   using reverse_iterator = FragmentListType::reverse_iterator;
  56
  57 private:
  58   MCSymbol *Begin;
  59   MCSymbol *End = nullptr;
  60   /// The alignment requirement of this section.
  61   unsigned Alignment = 1;
  62   /// The section index in the assemblers section list.
  63   unsigned Ordinal = 0;
  64   /// The index of this section in the layout order.
  65   unsigned LayoutOrder;
  66
  67   /// Keeping track of bundle-locked state.
  68   BundleLockStateType BundleLockState = NotBundleLocked;
  69
  70   /// Current nesting depth of bundle_lock directives.
  71   unsigned BundleLockNestingDepth = 0;
  72
  73   /// We've seen a bundle_lock directive but not its first instruction
  74   /// yet.
  75   bool BundleGroupBeforeFirstInst : 1;
  76
  77   /// Whether this section has had instructions emitted into it.
  78   bool HasInstructions : 1;
  79
  80   /// Whether this section has had data emitted into it.
  81   /// Right now this is only used by the ARM backend.
  82   bool HasData : 1;
  83
  84   bool IsRegistered : 1;
  85
  86   MCDummyFragment DummyFragment;
  87
  88   FragmentListType Fragments;
  89
  90   /// Mapping from subsection number to insertion point for subsection numbers
  91   /// below that number.
  92   SmallVector<std::pair<unsigned, MCFragment *>, 1> SubsectionFragmentMap;
  93
  94 protected:
  95   SectionVariant Variant;
  96   SectionKind Kind;
  97
  98   MCSection(SectionVariant V, SectionKind K, MCSymbol *Begin);
  99   ~MCSection();
 100
 101 public:
 102   MCSection(const MCSection &) = delete;
 103   MCSection &operator=(const MCSection &) = delete;
 104
 105   SectionKind getKind() const { return Kind; }
 106
 107   SectionVariant getVariant() const { return Variant; }
 108
 109   MCSymbol *getBeginSymbol() { return Begin; }
 110   const MCSymbol *getBeginSymbol() const {
 111     return const_cast<MCSection *>(this)->getBeginSymbol();
 112   }
 113   void setBeginSymbol(MCSymbol *Sym) {
 114     assert(!Begin);
 115     Begin = Sym;
 116   }
 117   MCSymbol *getEndSymbol(MCContext &Ctx);
 118   bool hasEnded() const;
 119
 120   unsigned getAlignment() const { return Alignment; }
 121   void setAlignment(unsigned Value) { Alignment = Value; }
 122
 123   unsigned getOrdinal() const { return Ordinal; }
 124   void setOrdinal(unsigned Value) { Ordinal = Value; }
 125
 126   unsigned getLayoutOrder() const { return LayoutOrder; }
 127   void setLayoutOrder(unsigned Value) { LayoutOrder = Value; }
 128
 129   BundleLockStateType getBundleLockState() const { return BundleLockState; }
 130   void setBundleLockState(BundleLockStateType NewState);
 131   bool isBundleLocked() const { return BundleLockState != NotBundleLocked; }
 132
 133   bool isBundleGroupBeforeFirstInst() const {
 134     return BundleGroupBeforeFirstInst;
 135   }
 136   void setBundleGroupBeforeFirstInst(bool IsFirst) {
 137     BundleGroupBeforeFirstInst = IsFirst;
 138   }
 139
 140   bool hasInstructions() const { return HasInstructions; }
 141   void setHasInstructions(bool Value) { HasInstructions = Value; }
 142
 143   bool hasData() const { return HasData; }
 144   void setHasData(bool Value) { HasData = Value; }
 145
 146   bool isRegistered() const { return IsRegistered; }
 147   void setIsRegistered(bool Value) { IsRegistered = Value; }
 148
 149   MCSection::FragmentListType &getFragmentList() { return Fragments; }
 150   const MCSection::FragmentListType &getFragmentList() const {
 151     return const_cast<MCSection *>(this)->getFragmentList();
 152   }
 153
 154   /// Support for MCFragment::getNextNode().
 155   static FragmentListType MCSection::*getSublistAccess(MCFragment *) {
 156     return &MCSection::Fragments;
 157   }
 158
 159   const MCDummyFragment &getDummyFragment() const { return DummyFragment; }
 160   MCDummyFragment &getDummyFragment() { return DummyFragment; }
 161
 162   iterator begin() { return Fragments.begin(); }
 163   const_iterator begin() const { return Fragments.begin(); }
 164
 165   iterator end() { return Fragments.end(); }
 166   const_iterator end() const { return Fragments.end(); }
 167
 168   reverse_iterator rbegin() { return Fragments.rbegin(); }
 169   const_reverse_iterator rbegin() const { return Fragments.rbegin(); }
 170
 171   reverse_iterator rend() { return Fragments.rend(); }
 172   const_reverse_iterator rend() const  { return Fragments.rend(); }
 173
 174   MCSection::iterator getSubsectionInsertionPoint(unsigned Subsection);
 175
 176   void dump() const;
 177
 178   virtual void PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
 179                                     raw_ostream &OS,
 180                                     const MCExpr *Subsection) const = 0;
 181
 182   /// Return true if a .align directive should use "optimized nops" to fill
 183   /// instead of 0s.
 184   virtual bool UseCodeAlign() const = 0;
 185
 186   /// Check whether this section is "virtual", that is has no actual object
 187   /// file contents.
 188   virtual bool isVirtualSection() const = 0;
 189 };
 190
 191 } // end namespace llvm
 192
 193 #endif // LLVM_MC_MCSECTION_H