LLVM  3.7.0
PPCAsmBackend.cpp
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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 
12 #include "llvm/MC/MCAsmBackend.h"
13 #include "llvm/MC/MCAssembler.h"
17 #include "llvm/MC/MCObjectWriter.h"
18 #include "llvm/MC/MCSectionMachO.h"
19 #include "llvm/MC/MCSymbolELF.h"
20 #include "llvm/MC/MCValue.h"
21 #include "llvm/Support/ELF.h"
23 #include "llvm/Support/MachO.h"
25 using namespace llvm;
26 
27 static uint64_t adjustFixupValue(unsigned Kind, uint64_t Value) {
28  switch (Kind) {
29  default:
30  llvm_unreachable("Unknown fixup kind!");
31  case FK_Data_1:
32  case FK_Data_2:
33  case FK_Data_4:
34  case FK_Data_8:
36  return Value;
39  return Value & 0xfffc;
42  return Value & 0x3fffffc;
44  return Value & 0xffff;
46  return Value & 0xfffc;
47  }
48 }
49 
50 static unsigned getFixupKindNumBytes(unsigned Kind) {
51  switch (Kind) {
52  default:
53  llvm_unreachable("Unknown fixup kind!");
54  case FK_Data_1:
55  return 1;
56  case FK_Data_2:
59  return 2;
60  case FK_Data_4:
65  return 4;
66  case FK_Data_8:
67  return 8;
69  return 0;
70  }
71 }
72 
73 namespace {
74 
75 class PPCAsmBackend : public MCAsmBackend {
76  const Target &TheTarget;
77  bool IsLittleEndian;
78 public:
79  PPCAsmBackend(const Target &T, bool isLittle) : MCAsmBackend(), TheTarget(T),
80  IsLittleEndian(isLittle) {}
81 
82  unsigned getNumFixupKinds() const override {
84  }
85 
86  const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override {
87  const static MCFixupKindInfo InfosBE[PPC::NumTargetFixupKinds] = {
88  // name offset bits flags
89  { "fixup_ppc_br24", 6, 24, MCFixupKindInfo::FKF_IsPCRel },
90  { "fixup_ppc_brcond14", 16, 14, MCFixupKindInfo::FKF_IsPCRel },
91  { "fixup_ppc_br24abs", 6, 24, 0 },
92  { "fixup_ppc_brcond14abs", 16, 14, 0 },
93  { "fixup_ppc_half16", 0, 16, 0 },
94  { "fixup_ppc_half16ds", 0, 14, 0 },
95  { "fixup_ppc_nofixup", 0, 0, 0 }
96  };
97  const static MCFixupKindInfo InfosLE[PPC::NumTargetFixupKinds] = {
98  // name offset bits flags
99  { "fixup_ppc_br24", 2, 24, MCFixupKindInfo::FKF_IsPCRel },
100  { "fixup_ppc_brcond14", 2, 14, MCFixupKindInfo::FKF_IsPCRel },
101  { "fixup_ppc_br24abs", 2, 24, 0 },
102  { "fixup_ppc_brcond14abs", 2, 14, 0 },
103  { "fixup_ppc_half16", 0, 16, 0 },
104  { "fixup_ppc_half16ds", 2, 14, 0 },
105  { "fixup_ppc_nofixup", 0, 0, 0 }
106  };
107 
108  if (Kind < FirstTargetFixupKind)
109  return MCAsmBackend::getFixupKindInfo(Kind);
110 
111  assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
112  "Invalid kind!");
113  return (IsLittleEndian? InfosLE : InfosBE)[Kind - FirstTargetFixupKind];
114  }
115 
116  void applyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
117  uint64_t Value, bool IsPCRel) const override {
118  Value = adjustFixupValue(Fixup.getKind(), Value);
119  if (!Value) return; // Doesn't change encoding.
120 
121  unsigned Offset = Fixup.getOffset();
122  unsigned NumBytes = getFixupKindNumBytes(Fixup.getKind());
123 
124  // For each byte of the fragment that the fixup touches, mask in the bits
125  // from the fixup value. The Value has been "split up" into the appropriate
126  // bitfields above.
127  for (unsigned i = 0; i != NumBytes; ++i) {
128  unsigned Idx = IsLittleEndian ? i : (NumBytes - 1 - i);
129  Data[Offset + i] |= uint8_t((Value >> (Idx * 8)) & 0xff);
130  }
131  }
132 
133  void processFixupValue(const MCAssembler &Asm, const MCAsmLayout &Layout,
134  const MCFixup &Fixup, const MCFragment *DF,
135  const MCValue &Target, uint64_t &Value,
136  bool &IsResolved) override {
137  switch ((PPC::Fixups)Fixup.getKind()) {
138  default: break;
139  case PPC::fixup_ppc_br24:
141  // If the target symbol has a local entry point we must not attempt
142  // to resolve the fixup directly. Emit a relocation and leave
143  // resolution of the final target address to the linker.
144  if (const MCSymbolRefExpr *A = Target.getSymA()) {
145  if (const auto *S = dyn_cast<MCSymbolELF>(&A->getSymbol())) {
146  // The "other" values are stored in the last 6 bits of the second
147  // byte. The traditional defines for STO values assume the full byte
148  // and thus the shift to pack it.
149  unsigned Other = S->getOther() << 2;
150  if ((Other & ELF::STO_PPC64_LOCAL_MASK) != 0)
151  IsResolved = false;
152  }
153  }
154  break;
155  }
156  }
157 
158  bool mayNeedRelaxation(const MCInst &Inst) const override {
159  // FIXME.
160  return false;
161  }
162 
163  bool fixupNeedsRelaxation(const MCFixup &Fixup,
164  uint64_t Value,
165  const MCRelaxableFragment *DF,
166  const MCAsmLayout &Layout) const override {
167  // FIXME.
168  llvm_unreachable("relaxInstruction() unimplemented");
169  }
170 
171 
172  void relaxInstruction(const MCInst &Inst, MCInst &Res) const override {
173  // FIXME.
174  llvm_unreachable("relaxInstruction() unimplemented");
175  }
176 
177  bool writeNopData(uint64_t Count, MCObjectWriter *OW) const override {
178  uint64_t NumNops = Count / 4;
179  for (uint64_t i = 0; i != NumNops; ++i)
180  OW->write32(0x60000000);
181 
182  OW->WriteZeros(Count % 4);
183 
184  return true;
185  }
186 
187  unsigned getPointerSize() const {
188  StringRef Name = TheTarget.getName();
189  if (Name == "ppc64" || Name == "ppc64le") return 8;
190  assert(Name == "ppc32" && "Unknown target name!");
191  return 4;
192  }
193 
194  bool isLittleEndian() const {
195  return IsLittleEndian;
196  }
197 };
198 } // end anonymous namespace
199 
200 
201 // FIXME: This should be in a separate file.
202 namespace {
203  class DarwinPPCAsmBackend : public PPCAsmBackend {
204  public:
205  DarwinPPCAsmBackend(const Target &T) : PPCAsmBackend(T, false) { }
206 
207  MCObjectWriter *createObjectWriter(raw_pwrite_stream &OS) const override {
208  bool is64 = getPointerSize() == 8;
210  OS,
211  /*Is64Bit=*/is64,
214  }
215  };
216 
217  class ELFPPCAsmBackend : public PPCAsmBackend {
218  uint8_t OSABI;
219  public:
220  ELFPPCAsmBackend(const Target &T, bool IsLittleEndian, uint8_t OSABI) :
221  PPCAsmBackend(T, IsLittleEndian), OSABI(OSABI) { }
222 
223  MCObjectWriter *createObjectWriter(raw_pwrite_stream &OS) const override {
224  bool is64 = getPointerSize() == 8;
225  return createPPCELFObjectWriter(OS, is64, isLittleEndian(), OSABI);
226  }
227  };
228 
229 } // end anonymous namespace
230 
232  const MCRegisterInfo &MRI,
233  const Triple &TT, StringRef CPU) {
234  if (TT.isOSDarwin())
235  return new DarwinPPCAsmBackend(T);
236 
237  uint8_t OSABI = MCELFObjectTargetWriter::getOSABI(TT.getOS());
238  bool IsLittleEndian = TT.getArch() == Triple::ppc64le;
239  return new ELFPPCAsmBackend(T, IsLittleEndian, OSABI);
240 }
OSType getOS() const
getOS - Get the parsed operating system type of this triple.
Definition: Triple.h:251
void WriteZeros(unsigned N)
This represents an "assembler immediate".
Definition: MCValue.h:44
fixup_ppc_brcond14abs - 14-bit absolute relocation for conditional branches.
Definition: PPCFixupKinds.h:34
Defines the object file and target independent interfaces used by the assembler backend to write nati...
Encode information on a single operation to perform on a byte sequence (e.g., an encoded instruction)...
Definition: MCFixup.h:62
Is this fixup kind PCrelative? This is used by the assembler backend to evaluate fixup values in a ta...
fixup_ppc_half16 - A 16-bit fixup corresponding to lo16(_foo) or ha16(_foo) for instrs like 'li' or '...
Definition: PPCFixupKinds.h:38
fixup_ppc_br24abs - 24-bit absolute relocation for direct branches like 'ba' and 'bla'.
Definition: PPCFixupKinds.h:30
Encapsulates the layout of an assembly file at a particular point in time.
Definition: MCAsmLayout.h:29
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
Definition: ErrorHandling.h:98
fixup_ppc_nofixup - Not a true fixup, but ties a symbol to a call to __tls_get_addr for the TLS gener...
Definition: PPCFixupKinds.h:47
Represent a reference to a symbol from inside an expression.
Definition: MCExpr.h:159
#define false
Definition: ConvertUTF.c:65
ELFYAML::ELF_STO Other
Definition: ELFYAML.cpp:591
A four-byte fixup.
Definition: MCFixup.h:26
MCObjectWriter * createPPCELFObjectWriter(raw_pwrite_stream &OS, bool Is64Bit, bool IsLittleEndian, uint8_t OSABI)
Construct an PPC ELF object writer.
static uint64_t getPointerSize(const Value *V, const DataLayout &DL, const TargetLibraryInfo *TLI)
static unsigned getFixupKindNumBytes(unsigned Kind)
ArchType getArch() const
getArch - Get the parsed architecture type of this triple.
Definition: Triple.h:242
uint32_t getOffset() const
Definition: MCFixup.h:91
Instances of this class represent a single low-level machine instruction.
Definition: MCInst.h:150
MCRegisterInfo base class - We assume that the target defines a static array of MCRegisterDesc object...
A relaxable fragment holds on to its MCInst, since it may need to be relaxed during the assembler lay...
Definition: MCAssembler.h:259
void write32(uint32_t Value)
MCAsmBackend * createPPCAsmBackend(const Target &T, const MCRegisterInfo &MRI, const Triple &TT, StringRef CPU)
MCFixupKind
Extensible enumeration to represent the type of a fixup.
Definition: MCFixup.h:23
MCFixupKind getKind() const
Definition: MCFixup.h:89
A one-byte fixup.
Definition: MCFixup.h:24
Triple - Helper class for working with autoconf configuration names.
Definition: Triple.h:44
MCObjectWriter * createPPCMachObjectWriter(raw_pwrite_stream &OS, bool Is64Bit, uint32_t CPUType, uint32_t CPUSubtype)
Construct a PPC Mach-O object writer.
PowerPC TLS Dynamic Call Fixup
bool isOSDarwin() const
isOSDarwin - Is this a "Darwin" OS (OS X or iOS).
Definition: Triple.h:404
const MCSymbolRefExpr * getSymA() const
Definition: MCValue.h:51
Target - Wrapper for Target specific information.
fixup_ppc_half16ds - A 14-bit fixup corresponding to lo16(_foo) with implied 2 zero bits for instrs l...
Definition: PPCFixupKinds.h:42
A eight-byte fixup.
Definition: MCFixup.h:27
Target independent information on a fixup kind.
An abstract base class for streams implementations that also support a pwrite operation.
Definition: raw_ostream.h:321
const ARM::ArchExtKind Kind
LLVM Value Representation.
Definition: Value.h:69
Generic interface to target specific assembler backends.
Definition: MCAsmBackend.h:34
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:40
static uint64_t adjustFixupValue(unsigned Kind, uint64_t Value)
fixup_ppc_brcond14 - 14-bit PC relative relocation for conditional branches.
Definition: PPCFixupKinds.h:26
virtual const MCFixupKindInfo & getFixupKindInfo(MCFixupKind Kind) const
Get information on a fixup kind.
A two-byte fixup.
Definition: MCFixup.h:25