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thirdparty/clang/include/llvm/CodeGen/MachineRelocation.h

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+//===-- llvm/CodeGen/MachineRelocation.h - Target Relocation ----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the MachineRelocation class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_MACHINERELOCATION_H
+#define LLVM_CODEGEN_MACHINERELOCATION_H
+
+#include "llvm/Support/DataTypes.h"
+#include <cassert>
+
+namespace llvm {
+class GlobalValue;
+class MachineBasicBlock;
+
+/// MachineRelocation - This represents a target-specific relocation value,
+/// produced by the code emitter.  This relocation is resolved after the has
+/// been emitted, either to an object file or to memory, when the target of the
+/// relocation can be resolved.
+///
+/// A relocation is made up of the following logical portions:
+///   1. An offset in the machine code buffer, the location to modify.
+///   2. A target specific relocation type (a number from 0 to 63).
+///   3. A symbol being referenced, either as a GlobalValue* or as a string.
+///   4. An optional constant value to be added to the reference.
+///   5. A bit, CanRewrite, which indicates to the JIT that a function stub is
+///      not needed for the relocation.
+///   6. An index into the GOT, if the target uses a GOT
+///
+class MachineRelocation {
+  enum AddressType {
+    isResult,         // Relocation has be transformed into its result pointer.
+    isGV,             // The Target.GV field is valid.
+    isIndirectSym,    // Relocation of an indirect symbol.
+    isBB,             // Relocation of BB address.
+    isExtSym,         // The Target.ExtSym field is valid.
+    isConstPool,      // Relocation of constant pool address.
+    isJumpTable,      // Relocation of jump table address.
+    isGOTIndex        // The Target.GOTIndex field is valid.
+  };
+  
+  /// Offset - This is the offset from the start of the code buffer of the
+  /// relocation to perform.
+  uintptr_t Offset;
+  
+  /// ConstantVal - A field that may be used by the target relocation type.
+  intptr_t ConstantVal;
+
+  union {
+    void *Result;           // If this has been resolved to a resolved pointer
+    GlobalValue *GV;        // If this is a pointer to a GV or an indirect ref.
+    MachineBasicBlock *MBB; // If this is a pointer to a LLVM BB
+    const char *ExtSym;     // If this is a pointer to a named symbol
+    unsigned Index;         // Constant pool / jump table index
+    unsigned GOTIndex;      // Index in the GOT of this symbol/global
+  } Target;
+
+  unsigned TargetReloType : 6; // The target relocation ID
+  AddressType AddrType    : 4; // The field of Target to use
+  bool MayNeedFarStub     : 1; // True if this relocation may require a far-stub
+  bool GOTRelative        : 1; // Should this relocation be relative to the GOT?
+  bool TargetResolve      : 1; // True if target should resolve the address
+
+public:
+ // Relocation types used in a generic implementation.  Currently, relocation
+ // entries for all things use the generic VANILLA type until they are refined
+ // into target relocation types.
+  enum RelocationType {
+    VANILLA
+  };
+  
+  /// MachineRelocation::getGV - Return a relocation entry for a GlobalValue.
+  ///
+  static MachineRelocation getGV(uintptr_t offset, unsigned RelocationType, 
+                                 GlobalValue *GV, intptr_t cst = 0,
+                                 bool MayNeedFarStub = 0,
+                                 bool GOTrelative = 0) {
+    assert((RelocationType & ~63) == 0 && "Relocation type too large!");
+    MachineRelocation Result;
+    Result.Offset = offset;
+    Result.ConstantVal = cst;
+    Result.TargetReloType = RelocationType;
+    Result.AddrType = isGV;
+    Result.MayNeedFarStub = MayNeedFarStub;
+    Result.GOTRelative = GOTrelative;
+    Result.TargetResolve = false;
+    Result.Target.GV = GV;
+    return Result;
+  }
+
+  /// MachineRelocation::getIndirectSymbol - Return a relocation entry for an
+  /// indirect symbol.
+  static MachineRelocation getIndirectSymbol(uintptr_t offset,
+                                             unsigned RelocationType, 
+                                             GlobalValue *GV, intptr_t cst = 0,
+                                             bool MayNeedFarStub = 0,
+                                             bool GOTrelative = 0) {
+    assert((RelocationType & ~63) == 0 && "Relocation type too large!");
+    MachineRelocation Result;
+    Result.Offset = offset;
+    Result.ConstantVal = cst;
+    Result.TargetReloType = RelocationType;
+    Result.AddrType = isIndirectSym;
+    Result.MayNeedFarStub = MayNeedFarStub;
+    Result.GOTRelative = GOTrelative;
+    Result.TargetResolve = false;
+    Result.Target.GV = GV;
+    return Result;
+  }
+
+  /// MachineRelocation::getBB - Return a relocation entry for a BB.
+  ///
+  static MachineRelocation getBB(uintptr_t offset,unsigned RelocationType,
+                                 MachineBasicBlock *MBB, intptr_t cst = 0) {
+    assert((RelocationType & ~63) == 0 && "Relocation type too large!");
+    MachineRelocation Result;
+    Result.Offset = offset;
+    Result.ConstantVal = cst;
+    Result.TargetReloType = RelocationType;
+    Result.AddrType = isBB;
+    Result.MayNeedFarStub = false;
+    Result.GOTRelative = false;
+    Result.TargetResolve = false;
+    Result.Target.MBB = MBB;
+    return Result;
+  }
+
+  /// MachineRelocation::getExtSym - Return a relocation entry for an external
+  /// symbol, like "free".
+  ///
+  static MachineRelocation getExtSym(uintptr_t offset, unsigned RelocationType, 
+                                     const char *ES, intptr_t cst = 0,
+                                     bool GOTrelative = 0,
+                                     bool NeedStub = true) {
+    assert((RelocationType & ~63) == 0 && "Relocation type too large!");
+    MachineRelocation Result;
+    Result.Offset = offset;
+    Result.ConstantVal = cst;
+    Result.TargetReloType = RelocationType;
+    Result.AddrType = isExtSym;
+    Result.MayNeedFarStub = NeedStub;
+    Result.GOTRelative = GOTrelative;
+    Result.TargetResolve = false;
+    Result.Target.ExtSym = ES;
+    return Result;
+  }
+
+  /// MachineRelocation::getConstPool - Return a relocation entry for a constant
+  /// pool entry.
+  ///
+  static MachineRelocation getConstPool(uintptr_t offset,unsigned RelocationType,
+                                        unsigned CPI, intptr_t cst = 0,
+                                        bool letTargetResolve = false) {
+    assert((RelocationType & ~63) == 0 && "Relocation type too large!");
+    MachineRelocation Result;
+    Result.Offset = offset;
+    Result.ConstantVal = cst;
+    Result.TargetReloType = RelocationType;
+    Result.AddrType = isConstPool;
+    Result.MayNeedFarStub = false;
+    Result.GOTRelative = false;
+    Result.TargetResolve = letTargetResolve;
+    Result.Target.Index = CPI;
+    return Result;
+  }
+
+  /// MachineRelocation::getJumpTable - Return a relocation entry for a jump
+  /// table entry.
+  ///
+  static MachineRelocation getJumpTable(uintptr_t offset,unsigned RelocationType,
+                                        unsigned JTI, intptr_t cst = 0,
+                                        bool letTargetResolve = false) {
+    assert((RelocationType & ~63) == 0 && "Relocation type too large!");
+    MachineRelocation Result;
+    Result.Offset = offset;
+    Result.ConstantVal = cst;
+    Result.TargetReloType = RelocationType;
+    Result.AddrType = isJumpTable;
+    Result.MayNeedFarStub = false;
+    Result.GOTRelative = false;
+    Result.TargetResolve = letTargetResolve;
+    Result.Target.Index = JTI;
+    return Result;
+  }
+
+  /// getMachineCodeOffset - Return the offset into the code buffer that the
+  /// relocation should be performed.
+  intptr_t getMachineCodeOffset() const {
+    return Offset;
+  }
+
+  /// getRelocationType - Return the target-specific relocation ID for this
+  /// relocation.
+  unsigned getRelocationType() const {
+    return TargetReloType;
+  }
+
+  /// getConstantVal - Get the constant value associated with this relocation.
+  /// This is often an offset from the symbol.
+  ///
+  intptr_t getConstantVal() const {
+    return ConstantVal;
+  }
+
+  /// setConstantVal - Set the constant value associated with this relocation.
+  /// This is often an offset from the symbol.
+  ///
+  void setConstantVal(intptr_t val) {
+    ConstantVal = val;
+  }
+
+  /// isGlobalValue - Return true if this relocation is a GlobalValue, as
+  /// opposed to a constant string.
+  bool isGlobalValue() const {
+    return AddrType == isGV;
+  }
+
+  /// isIndirectSymbol - Return true if this relocation is the address an
+  /// indirect symbol
+  bool isIndirectSymbol() const {
+    return AddrType == isIndirectSym;
+  }
+
+  /// isBasicBlock - Return true if this relocation is a basic block reference.
+  ///
+  bool isBasicBlock() const {
+    return AddrType == isBB;
+  }
+
+  /// isExternalSymbol - Return true if this is a constant string.
+  ///
+  bool isExternalSymbol() const {
+    return AddrType == isExtSym;
+  }
+
+  /// isConstantPoolIndex - Return true if this is a constant pool reference.
+  ///
+  bool isConstantPoolIndex() const {
+    return AddrType == isConstPool;
+  }
+
+  /// isJumpTableIndex - Return true if this is a jump table reference.
+  ///
+  bool isJumpTableIndex() const {
+    return AddrType == isJumpTable;
+  }
+
+  /// isGOTRelative - Return true the target wants the index into the GOT of
+  /// the symbol rather than the address of the symbol.
+  bool isGOTRelative() const {
+    return GOTRelative;
+  }
+
+  /// mayNeedFarStub - This function returns true if the JIT for this target may
+  /// need either a stub function or an indirect global-variable load to handle
+  /// the relocated GlobalValue reference.  For example, the x86-64 call
+  /// instruction can only call functions within +/-2GB of the call site.
+  /// Anything farther away needs a longer mov+call sequence, which can't just
+  /// be written on top of the existing call.
+  bool mayNeedFarStub() const {
+    return MayNeedFarStub;
+  }
+
+  /// letTargetResolve - Return true if the target JITInfo is usually
+  /// responsible for resolving the address of this relocation.
+  bool letTargetResolve() const {
+    return TargetResolve;
+  }
+
+  /// getGlobalValue - If this is a global value reference, return the
+  /// referenced global.
+  GlobalValue *getGlobalValue() const {
+    assert((isGlobalValue() || isIndirectSymbol()) &&
+           "This is not a global value reference!");
+    return Target.GV;
+  }
+
+  MachineBasicBlock *getBasicBlock() const {
+    assert(isBasicBlock() && "This is not a basic block reference!");
+    return Target.MBB;
+  }
+
+  /// getString - If this is a string value, return the string reference.
+  ///
+  const char *getExternalSymbol() const {
+    assert(isExternalSymbol() && "This is not an external symbol reference!");
+    return Target.ExtSym;
+  }
+
+  /// getConstantPoolIndex - If this is a const pool reference, return
+  /// the index into the constant pool.
+  unsigned getConstantPoolIndex() const {
+    assert(isConstantPoolIndex() && "This is not a constant pool reference!");
+    return Target.Index;
+  }
+
+  /// getJumpTableIndex - If this is a jump table reference, return
+  /// the index into the jump table.
+  unsigned getJumpTableIndex() const {
+    assert(isJumpTableIndex() && "This is not a jump table reference!");
+    return Target.Index;
+  }
+
+  /// getResultPointer - Once this has been resolved to point to an actual
+  /// address, this returns the pointer.
+  void *getResultPointer() const {
+    assert(AddrType == isResult && "Result pointer isn't set yet!");
+    return Target.Result;
+  }
+
+  /// setResultPointer - Set the result to the specified pointer value.
+  ///
+  void setResultPointer(void *Ptr) {
+    Target.Result = Ptr;
+    AddrType = isResult;
+  }
+
+  /// setGOTIndex - Set the GOT index to a specific value.
+  void setGOTIndex(unsigned idx) {
+    AddrType = isGOTIndex;
+    Target.GOTIndex = idx;
+  }
+
+  /// getGOTIndex - Once this has been resolved to an entry in the GOT,
+  /// this returns that index.  The index is from the lowest address entry
+  /// in the GOT.
+  unsigned getGOTIndex() const {
+    assert(AddrType == isGOTIndex);
+    return Target.GOTIndex;
+  }
+};
+}
+
+#endif