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//===-- PPCMachOWriter.cpp - Emit a Mach-O file for the PowerPC backend ---===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Nate Begeman and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements a Mach-O writer for the PowerPC backend. The public
// interface to this file is the createPPCMachOObjectWriterPass function.
//
//===----------------------------------------------------------------------===//
#include "PPCRelocations.h"
#include "PPCTargetMachine.h"
#include "llvm/PassManager.h"
#include "llvm/CodeGen/MachOWriter.h"
#include "llvm/Support/Compiler.h"
using namespace llvm;
namespace {
class VISIBILITY_HIDDEN PPCMachOWriter : public MachOWriter {
public:
PPCMachOWriter(std::ostream &O, PPCTargetMachine &TM) : MachOWriter(O, TM) {
if (TM.getTargetData()->getPointerSizeInBits() == 64) {
Header.cputype = MachOHeader::CPU_TYPE_POWERPC64;
} else {
Header.cputype = MachOHeader::CPU_TYPE_POWERPC;
}
Header.cpusubtype = MachOHeader::CPU_SUBTYPE_POWERPC_ALL;
}
virtual void GetTargetRelocation(MachOSection &MOS, MachineRelocation &MR,
uint64_t Addr);
// Constants for the relocation r_type field.
// see <mach-o/ppc/reloc.h>
enum { PPC_RELOC_VANILLA, // generic relocation
PPC_RELOC_PAIR, // the second relocation entry of a pair
PPC_RELOC_BR14, // 14 bit branch displacement to word address
PPC_RELOC_BR24, // 24 bit branch displacement to word address
PPC_RELOC_HI16, // a PAIR follows with the low 16 bits
PPC_RELOC_LO16, // a PAIR follows with the high 16 bits
PPC_RELOC_HA16, // a PAIR follows, which is sign extended to 32b
PPC_RELOC_LO14 // LO16 with low 2 bits implicitly zero
};
};
}
/// addPPCMachOObjectWriterPass - Returns a pass that outputs the generated code
/// as a Mach-O object file.
///
void llvm::addPPCMachOObjectWriterPass(FunctionPassManager &FPM,
std::ostream &O, PPCTargetMachine &TM) {
PPCMachOWriter *EW = new PPCMachOWriter(O, TM);
FPM.add(EW);
FPM.add(createPPCCodeEmitterPass(TM, EW->getMachineCodeEmitter()));
}
/// GetTargetRelocation - For the MachineRelocation MR, convert it to one or
/// more PowerPC MachORelocation(s), add the new relocations to the
/// MachOSection, and rewrite the instruction at the section offset if required
/// by that relocation type.
void PPCMachOWriter::GetTargetRelocation(MachOSection &MOS,
MachineRelocation &MR,
uint64_t Addr) {
// Keep track of whether or not this is an externally defined relocation.
uint32_t index = MOS.Index;
bool isExtern = false;
// Get the address of the instruction to rewrite
unsigned char *RelocPos = &MOS.SectionData[0] + MR.getMachineCodeOffset();
// Get the address of whatever it is we're relocating, if possible.
if (MR.isGlobalValue()) {
// determine whether or not its external and then figure out what section
// we put it in if it's a locally defined symbol.
} else if (MR.isString()) {
// lookup in global values?
} else {
assert((MR.isConstantPoolIndex() || MR.isJumpTableIndex()) &&
"Unhandled MachineRelocation type!");
}
switch ((PPC::RelocationType)MR.getRelocationType()) {
default: assert(0 && "Unknown PPC relocation type!");
case PPC::reloc_pcrel_bx:
case PPC::reloc_pcrel_bcx:
case PPC::reloc_absolute_low_ix:
assert(0 && "Unhandled PPC relocation type!");
break;
case PPC::reloc_absolute_high:
{
MachORelocation HA16(MR.getMachineCodeOffset(), index, false, 2, isExtern,
PPC_RELOC_HA16);
MachORelocation PAIR(Addr & 0xFFFF, 0xFFFFFF, false, 2, isExtern,
PPC_RELOC_PAIR);
outword(RelocBuffer, HA16.r_address);
outword(RelocBuffer, HA16.getPackedFields());
outword(RelocBuffer, PAIR.r_address);
outword(RelocBuffer, PAIR.getPackedFields());
}
MOS.nreloc += 2;
Addr += 0x8000;
*(unsigned *)RelocPos &= 0xFFFF0000;
*(unsigned *)RelocPos |= ((Addr >> 16) & 0xFFFF);
break;
case PPC::reloc_absolute_low:
{
MachORelocation LO16(MR.getMachineCodeOffset(), index, false, 2, isExtern,
PPC_RELOC_LO16);
MachORelocation PAIR(Addr >> 16, 0xFFFFFF, false, 2, isExtern,
PPC_RELOC_PAIR);
outword(RelocBuffer, LO16.r_address);
outword(RelocBuffer, LO16.getPackedFields());
outword(RelocBuffer, PAIR.r_address);
outword(RelocBuffer, PAIR.getPackedFields());
}
MOS.nreloc += 2;
*(unsigned *)RelocPos &= 0xFFFF0000;
*(unsigned *)RelocPos |= (Addr & 0xFFFF);
break;
}
}
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