//===-- 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