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//===-- X86ELFRelocationInfo.cpp ----------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "MCTargetDesc/X86MCTargetDesc.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCRelocationInfo.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Object/ELFObjectFile.h"
#include "llvm/Support/ELF.h"
using namespace llvm;
using namespace object;
using namespace ELF;
namespace {
class X86_64ELFRelocationInfo : public MCRelocationInfo {
public:
X86_64ELFRelocationInfo(MCContext &Ctx) : MCRelocationInfo(Ctx) {}
const MCExpr *createExprForRelocation(RelocationRef Rel) override {
uint64_t RelType; Rel.getType(RelType);
symbol_iterator SymI = Rel.getSymbol();
StringRef SymName; SymI->getName(SymName);
uint64_t SymAddr; SymI->getAddress(SymAddr);
uint64_t SymSize = SymI->getSize();
auto *Obj = cast<ELFObjectFileBase>(Rel.getObjectFile());
int64_t Addend = *Obj->getRelocationAddend(Rel.getRawDataRefImpl());
MCSymbol *Sym = Ctx.getOrCreateSymbol(SymName);
// FIXME: check that the value is actually the same.
if (!Sym->isVariable())
Sym->setVariableValue(MCConstantExpr::create(SymAddr, Ctx));
const MCExpr *Expr = nullptr;
// If hasAddend is true, then we need to add Addend (r_addend) to Expr.
bool hasAddend = false;
// The AMD64 SysV ABI says:
// A: the addend used to compute the value of the relocatable field.
// B: the base address at which a shared object has been loaded into memory
// during execution. Generally, a shared object is built with a 0 base
// virtual address, but the execution address will be different.
// G: the offset into the global offset table at which the relocation
// entry's symbol will reside during execution.
// GOT: the address of the global offset table.
// L: the place (section offset or address) of the Procedure Linkage Table
// entry for a symbol.
// P: the place (section offset or address) of the storage unit being
// relocated (computed using r_offset).
// S: the value of the symbol whose index resides in the relocation entry.
// Z: the size of the symbol whose index resides in the relocation entry.
switch(RelType) {
case R_X86_64_NONE:
case R_X86_64_COPY:
// none
break;
case R_X86_64_64:
case R_X86_64_16:
case R_X86_64_8:
// S + A
case R_X86_64_32:
case R_X86_64_32S:
// S + A (We don't care about the result not fitting in 32 bits.)
case R_X86_64_PC32:
case R_X86_64_PC16:
case R_X86_64_PC8:
case R_X86_64_PC64:
// S + A - P (P/pcrel is implicit)
hasAddend = true;
Expr = MCSymbolRefExpr::create(Sym, Ctx);
break;
case R_X86_64_GOT32:
case R_X86_64_GOT64:
case R_X86_64_GOTPC32:
case R_X86_64_GOTPC64:
case R_X86_64_GOTPLT64:
// G + A
hasAddend = true;
Expr = MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOT, Ctx);
break;
case R_X86_64_PLT32:
// L + A - P -> S@PLT + A
hasAddend = true;
Expr = MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_PLT, Ctx);
break;
case R_X86_64_GLOB_DAT:
case R_X86_64_JUMP_SLOT:
// S
Expr = MCSymbolRefExpr::create(Sym, Ctx);
break;
case R_X86_64_GOTPCREL:
case R_X86_64_GOTPCREL64:
// G + GOT + A - P -> S@GOTPCREL + A
hasAddend = true;
Expr = MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOTPCREL, Ctx);
break;
case R_X86_64_GOTOFF64:
// S + A - GOT
Expr = MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOTOFF, Ctx);
break;
case R_X86_64_PLTOFF64:
// L + A - GOT
break;
case R_X86_64_SIZE32:
case R_X86_64_SIZE64:
// Z + A
Expr = MCConstantExpr::create(SymSize, Ctx);
break;
default:
Expr = MCSymbolRefExpr::create(Sym, Ctx);
break;
}
if (Expr && hasAddend && Addend != 0)
Expr = MCBinaryExpr::createAdd(Expr,
MCConstantExpr::create(Addend, Ctx),
Ctx);
return Expr;
}
};
} // End unnamed namespace
/// createX86ELFRelocationInfo - Construct an X86 Mach-O RelocationInfo.
MCRelocationInfo *llvm::createX86_64ELFRelocationInfo(MCContext &Ctx) {
// We only handle x86-64 for now.
return new X86_64ELFRelocationInfo(Ctx);
}
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