1//===-- PPCAsmBackend.cpp - PPC Assembler Backend -------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10#include "MCTargetDesc/PPCMCTargetDesc.h"
11#include "MCTargetDesc/PPCFixupKinds.h"
12#include "llvm/MC/MCAsmBackend.h"
13#include "llvm/MC/MCELFObjectWriter.h"
14#include "llvm/MC/MCFixupKindInfo.h"
15#include "llvm/MC/MCMachObjectWriter.h"
16#include "llvm/MC/MCSectionMachO.h"
17#include "llvm/MC/MCObjectWriter.h"
18#include "llvm/MC/MCValue.h"
19#include "llvm/Object/MachOFormat.h"
20#include "llvm/Support/ELF.h"
21#include "llvm/Support/ErrorHandling.h"
22#include "llvm/Support/TargetRegistry.h"
23using namespace llvm;
24
25static unsigned adjustFixupValue(unsigned Kind, uint64_t Value) {
26  switch (Kind) {
27  default:
28    llvm_unreachable("Unknown fixup kind!");
29  case FK_Data_1:
30  case FK_Data_2:
31  case FK_Data_4:
32    return Value;
33  case PPC::fixup_ppc_brcond14:
34    return Value & 0x3ffc;
35  case PPC::fixup_ppc_br24:
36    return Value & 0x3fffffc;
37#if 0
38  case PPC::fixup_ppc_hi16:
39    return (Value >> 16) & 0xffff;
40#endif
41  case PPC::fixup_ppc_ha16:
42    return ((Value >> 16) + ((Value & 0x8000) ? 1 : 0)) & 0xffff;
43  case PPC::fixup_ppc_lo16:
44    return Value & 0xffff;
45  }
46}
47
48namespace {
49class PPCMachObjectWriter : public MCMachObjectTargetWriter {
50public:
51  PPCMachObjectWriter(bool Is64Bit, uint32_t CPUType,
52                      uint32_t CPUSubtype)
53    : MCMachObjectTargetWriter(Is64Bit, CPUType, CPUSubtype) {}
54
55  void RecordRelocation(MachObjectWriter *Writer,
56                        const MCAssembler &Asm, const MCAsmLayout &Layout,
57                        const MCFragment *Fragment, const MCFixup &Fixup,
58                        MCValue Target, uint64_t &FixedValue) {}
59};
60
61class PPCAsmBackend : public MCAsmBackend {
62const Target &TheTarget;
63public:
64  PPCAsmBackend(const Target &T) : MCAsmBackend(), TheTarget(T) {}
65
66  unsigned getNumFixupKinds() const { return PPC::NumTargetFixupKinds; }
67
68  const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const {
69    const static MCFixupKindInfo Infos[PPC::NumTargetFixupKinds] = {
70      // name                    offset  bits  flags
71      { "fixup_ppc_br24",        6,      24,   MCFixupKindInfo::FKF_IsPCRel },
72      { "fixup_ppc_brcond14",    16,     14,   MCFixupKindInfo::FKF_IsPCRel },
73      { "fixup_ppc_lo16",        16,     16,   0 },
74      { "fixup_ppc_ha16",        16,     16,   0 },
75      { "fixup_ppc_lo14",        16,     14,   0 }
76    };
77
78    if (Kind < FirstTargetFixupKind)
79      return MCAsmBackend::getFixupKindInfo(Kind);
80
81    assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
82           "Invalid kind!");
83    return Infos[Kind - FirstTargetFixupKind];
84  }
85
86  bool mayNeedRelaxation(const MCInst &Inst) const {
87    // FIXME.
88    return false;
89  }
90
91  bool fixupNeedsRelaxation(const MCFixup &Fixup,
92                            uint64_t Value,
93                            const MCInstFragment *DF,
94                            const MCAsmLayout &Layout) const {
95    // FIXME.
96    llvm_unreachable("relaxInstruction() unimplemented");
97  }
98
99
100  void relaxInstruction(const MCInst &Inst, MCInst &Res) const {
101    // FIXME.
102    llvm_unreachable("relaxInstruction() unimplemented");
103  }
104
105  bool writeNopData(uint64_t Count, MCObjectWriter *OW) const {
106    // FIXME: Zero fill for now. That's not right, but at least will get the
107    // section size right.
108    for (uint64_t i = 0; i != Count; ++i)
109      OW->Write8(0);
110    return true;
111  }
112
113  unsigned getPointerSize() const {
114    StringRef Name = TheTarget.getName();
115    if (Name == "ppc64") return 8;
116    assert(Name == "ppc32" && "Unknown target name!");
117    return 4;
118  }
119};
120} // end anonymous namespace
121
122
123// FIXME: This should be in a separate file.
124namespace {
125  class DarwinPPCAsmBackend : public PPCAsmBackend {
126  public:
127    DarwinPPCAsmBackend(const Target &T) : PPCAsmBackend(T) { }
128
129    void applyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
130                    uint64_t Value) const {
131      llvm_unreachable("UNIMP");
132    }
133
134    MCObjectWriter *createObjectWriter(raw_ostream &OS) const {
135      bool is64 = getPointerSize() == 8;
136      return createMachObjectWriter(new PPCMachObjectWriter(
137                                      /*Is64Bit=*/is64,
138                                      (is64 ? object::mach::CTM_PowerPC64 :
139                                       object::mach::CTM_PowerPC),
140                                      object::mach::CSPPC_ALL),
141                                    OS, /*IsLittleEndian=*/false);
142    }
143
144    virtual bool doesSectionRequireSymbols(const MCSection &Section) const {
145      return false;
146    }
147  };
148
149  class ELFPPCAsmBackend : public PPCAsmBackend {
150    uint8_t OSABI;
151  public:
152    ELFPPCAsmBackend(const Target &T, uint8_t OSABI) :
153      PPCAsmBackend(T), OSABI(OSABI) { }
154
155    void applyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
156                    uint64_t Value) const {
157      Value = adjustFixupValue(Fixup.getKind(), Value);
158      if (!Value) return;           // Doesn't change encoding.
159
160      unsigned Offset = Fixup.getOffset();
161
162      // For each byte of the fragment that the fixup touches, mask in the bits from
163      // the fixup value. The Value has been "split up" into the appropriate
164      // bitfields above.
165      for (unsigned i = 0; i != 4; ++i)
166        Data[Offset + i] |= uint8_t((Value >> ((4 - i - 1)*8)) & 0xff);
167    }
168
169    MCObjectWriter *createObjectWriter(raw_ostream &OS) const {
170      bool is64 = getPointerSize() == 8;
171      return createPPCELFObjectWriter(OS, is64, OSABI);
172    }
173
174    virtual bool doesSectionRequireSymbols(const MCSection &Section) const {
175      return false;
176    }
177  };
178
179} // end anonymous namespace
180
181
182
183
184MCAsmBackend *llvm::createPPCAsmBackend(const Target &T, StringRef TT, StringRef CPU) {
185  if (Triple(TT).isOSDarwin())
186    return new DarwinPPCAsmBackend(T);
187
188  uint8_t OSABI = MCELFObjectTargetWriter::getOSABI(Triple(TT).getOS());
189  return new ELFPPCAsmBackend(T, OSABI);
190}
191