include/llvm/MC/MCLinkerOptimizationHint.h

   1 //===- MCLinkerOptimizationHint.h - LOH interface ---------------*- C++ -*-===//
   2 //
   3 //
   4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   5 // See https://llvm.org/LICENSE.txt for license information.
   6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file declares some helpers classes to handle Linker Optimization Hint
  11 // (LOH).
  12 //
  13 // FIXME: LOH interface supports only MachO format at the moment.
  14 //===----------------------------------------------------------------------===//
  15
  16 #ifndef LLVM_MC_MCLINKEROPTIMIZATIONHINT_H
  17 #define LLVM_MC_MCLINKEROPTIMIZATIONHINT_H
  18
  19 #include "llvm/ADT/SmallVector.h"
  20 #include "llvm/ADT/StringRef.h"
  21 #include "llvm/ADT/StringSwitch.h"
  22 #include "llvm/Support/raw_ostream.h"
  23 #include <cassert>
  24 #include <cstdint>
  25
  26 namespace llvm {
  27
  28 class MachObjectWriter;
  29 class MCAsmLayout;
  30 class MCSymbol;
  31
  32 /// Linker Optimization Hint Type.
  33 enum MCLOHType {
  34   MCLOH_AdrpAdrp = 0x1u,      ///< Adrp xY, _v1@PAGE -> Adrp xY, _v2@PAGE.
  35   MCLOH_AdrpLdr = 0x2u,       ///< Adrp _v@PAGE -> Ldr _v@PAGEOFF.
  36   MCLOH_AdrpAddLdr = 0x3u,    ///< Adrp _v@PAGE -> Add _v@PAGEOFF -> Ldr.
  37   MCLOH_AdrpLdrGotLdr = 0x4u, ///< Adrp _v@GOTPAGE -> Ldr _v@GOTPAGEOFF -> Ldr.
  38   MCLOH_AdrpAddStr = 0x5u,    ///< Adrp _v@PAGE -> Add _v@PAGEOFF -> Str.
  39   MCLOH_AdrpLdrGotStr = 0x6u, ///< Adrp _v@GOTPAGE -> Ldr _v@GOTPAGEOFF -> Str.
  40   MCLOH_AdrpAdd = 0x7u,       ///< Adrp _v@PAGE -> Add _v@PAGEOFF.
  41   MCLOH_AdrpLdrGot = 0x8u     ///< Adrp _v@GOTPAGE -> Ldr _v@GOTPAGEOFF.
  42 };
  43
  44 static inline StringRef MCLOHDirectiveName() {
  45   return StringRef(".loh");
  46 }
  47
  48 static inline bool isValidMCLOHType(unsigned Kind) {
  49   return Kind >= MCLOH_AdrpAdrp && Kind <= MCLOH_AdrpLdrGot;
  50 }
  51
  52 static inline int MCLOHNameToId(StringRef Name) {
  53 #define MCLOHCaseNameToId(Name)     .Case(#Name, MCLOH_ ## Name)
  54   return StringSwitch<int>(Name)
  55     MCLOHCaseNameToId(AdrpAdrp)
  56     MCLOHCaseNameToId(AdrpLdr)
  57     MCLOHCaseNameToId(AdrpAddLdr)
  58     MCLOHCaseNameToId(AdrpLdrGotLdr)
  59     MCLOHCaseNameToId(AdrpAddStr)
  60     MCLOHCaseNameToId(AdrpLdrGotStr)
  61     MCLOHCaseNameToId(AdrpAdd)
  62     MCLOHCaseNameToId(AdrpLdrGot)
  63     .Default(-1);
  64 #undef MCLOHCaseNameToId
  65 }
  66
  67 static inline StringRef MCLOHIdToName(MCLOHType Kind) {
  68 #define MCLOHCaseIdToName(Name)      case MCLOH_ ## Name: return StringRef(#Name);
  69   switch (Kind) {
  70     MCLOHCaseIdToName(AdrpAdrp);
  71     MCLOHCaseIdToName(AdrpLdr);
  72     MCLOHCaseIdToName(AdrpAddLdr);
  73     MCLOHCaseIdToName(AdrpLdrGotLdr);
  74     MCLOHCaseIdToName(AdrpAddStr);
  75     MCLOHCaseIdToName(AdrpLdrGotStr);
  76     MCLOHCaseIdToName(AdrpAdd);
  77     MCLOHCaseIdToName(AdrpLdrGot);
  78   }
  79   return StringRef();
  80 #undef MCLOHCaseIdToName
  81 }
  82
  83 static inline int MCLOHIdToNbArgs(MCLOHType Kind) {
  84   switch (Kind) {
  85     // LOH with two arguments
  86   case MCLOH_AdrpAdrp:
  87   case MCLOH_AdrpLdr:
  88   case MCLOH_AdrpAdd:
  89   case MCLOH_AdrpLdrGot:
  90     return 2;
  91     // LOH with three arguments
  92   case MCLOH_AdrpAddLdr:
  93   case MCLOH_AdrpLdrGotLdr:
  94   case MCLOH_AdrpAddStr:
  95   case MCLOH_AdrpLdrGotStr:
  96     return 3;
  97   }
  98   return -1;
  99 }
 100
 101 /// Store Linker Optimization Hint information (LOH).
 102 class MCLOHDirective {
 103   MCLOHType Kind;
 104
 105   /// Arguments of this directive. Order matters.
 106   SmallVector<MCSymbol *, 3> Args;
 107
 108   /// Emit this directive in \p OutStream using the information available
 109   /// in the given \p ObjWriter and \p Layout to get the address of the
 110   /// arguments within the object file.
 111   void emit_impl(raw_ostream &OutStream, const MachObjectWriter &ObjWriter,
 112                  const MCAsmLayout &Layout) const;
 113
 114 public:
 115   using LOHArgs = SmallVectorImpl<MCSymbol *>;
 116
 117   MCLOHDirective(MCLOHType Kind, const LOHArgs &Args)
 118       : Kind(Kind), Args(Args.begin(), Args.end()) {
 119     assert(isValidMCLOHType(Kind) && "Invalid LOH directive type!");
 120   }
 121
 122   MCLOHType getKind() const { return Kind; }
 123
 124   const LOHArgs &getArgs() const { return Args; }
 125
 126   /// Emit this directive as:
 127   /// <kind, numArgs, addr1, ..., addrN>
 128   void emit(MachObjectWriter &ObjWriter, const MCAsmLayout &Layout) const;
 129
 130   /// Get the size in bytes of this directive if emitted in \p ObjWriter with
 131   /// the given \p Layout.
 132   uint64_t getEmitSize(const MachObjectWriter &ObjWriter,
 133                        const MCAsmLayout &Layout) const;
 134 };
 135
 136 class MCLOHContainer {
 137   /// Keep track of the emit size of all the LOHs.
 138   mutable uint64_t EmitSize = 0;
 139
 140   /// Keep track of all LOH directives.
 141   SmallVector<MCLOHDirective, 32> Directives;
 142
 143 public:
 144   using LOHDirectives = SmallVectorImpl<MCLOHDirective>;
 145
 146   MCLOHContainer() = default;
 147
 148   /// Const accessor to the directives.
 149   const LOHDirectives &getDirectives() const {
 150     return Directives;
 151   }
 152
 153   /// Add the directive of the given kind \p Kind with the given arguments
 154   /// \p Args to the container.
 155   void addDirective(MCLOHType Kind, const MCLOHDirective::LOHArgs &Args) {
 156     Directives.push_back(MCLOHDirective(Kind, Args));
 157   }
 158
 159   /// Get the size of the directives if emitted.
 160   uint64_t getEmitSize(const MachObjectWriter &ObjWriter,
 161                        const MCAsmLayout &Layout) const {
 162     if (!EmitSize) {
 163       for (const MCLOHDirective &D : Directives)
 164         EmitSize += D.getEmitSize(ObjWriter, Layout);
 165     }
 166     return EmitSize;
 167   }
 168
 169   /// Emit all Linker Optimization Hint in one big table.
 170   /// Each line of the table is emitted by LOHDirective::emit.
 171   void emit(MachObjectWriter &ObjWriter, const MCAsmLayout &Layout) const {
 172     for (const MCLOHDirective &D : Directives)
 173       D.emit(ObjWriter, Layout);
 174   }
 175
 176   void reset() {
 177     Directives.clear();
 178     EmitSize = 0;
 179   }
 180 };
 181
 182 // Add types for specialized template using MCSymbol.
 183 using MCLOHArgs = MCLOHDirective::LOHArgs;
 184 using MCLOHDirectives = MCLOHContainer::LOHDirectives;
 185
 186 } // end namespace llvm
 187
 188 #endif // LLVM_MC_MCLINKEROPTIMIZATIONHINT_H