MipsMCCodeEmitter.cpp revision d3107fbc54a5b5156f0aabc8788724f1469eb9df 
1//===-- MipsMCCodeEmitter.cpp - Convert Mips Code to Machine Code ---------===//
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// This file implements the MipsMCCodeEmitter class.
11//
12//===----------------------------------------------------------------------===//
13//
14#define DEBUG_TYPE "mccodeemitter"
15#include "MCTargetDesc/MipsBaseInfo.h"
16#include "MCTargetDesc/MipsDirectObjLower.h"
17#include "MCTargetDesc/MipsFixupKinds.h"
18#include "MCTargetDesc/MipsMCTargetDesc.h"
19#include "llvm/ADT/APFloat.h"
20#include "llvm/ADT/Statistic.h"
21#include "llvm/MC/MCCodeEmitter.h"
22#include "llvm/MC/MCContext.h"
23#include "llvm/MC/MCExpr.h"
24#include "llvm/MC/MCInst.h"
25#include "llvm/MC/MCInstrInfo.h"
26#include "llvm/MC/MCRegisterInfo.h"
27#include "llvm/MC/MCSubtargetInfo.h"
28#include "llvm/Support/raw_ostream.h"
29
30using namespace llvm;
31
32namespace {
33class MipsMCCodeEmitter : public MCCodeEmitter {
34  MipsMCCodeEmitter(const MipsMCCodeEmitter &) LLVM_DELETED_FUNCTION;
35  void operator=(const MipsMCCodeEmitter &) LLVM_DELETED_FUNCTION;
36  const MCInstrInfo &MCII;
37  MCContext &Ctx;
38  bool IsLittleEndian;
39
40public:
41  MipsMCCodeEmitter(const MCInstrInfo &mcii, MCContext &Ctx_,
42                    const MCSubtargetInfo &sti, bool IsLittle) :
43    MCII(mcii), Ctx(Ctx_), IsLittleEndian(IsLittle) {}
44
45  ~MipsMCCodeEmitter() {}
46
47  void EmitByte(unsigned char C, raw_ostream &OS) const {
48    OS << (char)C;
49  }
50
51  void EmitInstruction(uint64_t Val, unsigned Size, raw_ostream &OS) const {
52    // Output the instruction encoding in little endian byte order.
53    for (unsigned i = 0; i < Size; ++i) {
54      unsigned Shift = IsLittleEndian ? i * 8 : (Size - 1 - i) * 8;
55      EmitByte((Val >> Shift) & 0xff, OS);
56    }
57  }
58
59  void EncodeInstruction(const MCInst &MI, raw_ostream &OS,
60                         SmallVectorImpl<MCFixup> &Fixups) const;
61
62  // getBinaryCodeForInstr - TableGen'erated function for getting the
63  // binary encoding for an instruction.
64  uint64_t getBinaryCodeForInstr(const MCInst &MI,
65                                 SmallVectorImpl<MCFixup> &Fixups) const;
66
67  // getBranchJumpOpValue - Return binary encoding of the jump
68  // target operand. If the machine operand requires relocation,
69  // record the relocation and return zero.
70   unsigned getJumpTargetOpValue(const MCInst &MI, unsigned OpNo,
71                                 SmallVectorImpl<MCFixup> &Fixups) const;
72
73   // getBranchTargetOpValue - Return binary encoding of the branch
74   // target operand. If the machine operand requires relocation,
75   // record the relocation and return zero.
76  unsigned getBranchTargetOpValue(const MCInst &MI, unsigned OpNo,
77                                  SmallVectorImpl<MCFixup> &Fixups) const;
78
79   // getMachineOpValue - Return binary encoding of operand. If the machin
80   // operand requires relocation, record the relocation and return zero.
81  unsigned getMachineOpValue(const MCInst &MI,const MCOperand &MO,
82                             SmallVectorImpl<MCFixup> &Fixups) const;
83
84  unsigned getMemEncoding(const MCInst &MI, unsigned OpNo,
85                          SmallVectorImpl<MCFixup> &Fixups) const;
86  unsigned getSizeExtEncoding(const MCInst &MI, unsigned OpNo,
87                              SmallVectorImpl<MCFixup> &Fixups) const;
88  unsigned getSizeInsEncoding(const MCInst &MI, unsigned OpNo,
89                              SmallVectorImpl<MCFixup> &Fixups) const;
90
91}; // class MipsMCCodeEmitter
92}  // namespace
93
94MCCodeEmitter *llvm::createMipsMCCodeEmitterEB(const MCInstrInfo &MCII,
95                                               const MCRegisterInfo &MRI,
96                                               const MCSubtargetInfo &STI,
97                                               MCContext &Ctx)
98{
99  return new MipsMCCodeEmitter(MCII, Ctx, STI, false);
100}
101
102MCCodeEmitter *llvm::createMipsMCCodeEmitterEL(const MCInstrInfo &MCII,
103                                               const MCRegisterInfo &MRI,
104                                               const MCSubtargetInfo &STI,
105                                               MCContext &Ctx)
106{
107  return new MipsMCCodeEmitter(MCII, Ctx, STI, true);
108}
109
110/// EncodeInstruction - Emit the instruction.
111/// Size the instruction (currently only 4 bytes
112void MipsMCCodeEmitter::
113EncodeInstruction(const MCInst &MI, raw_ostream &OS,
114                  SmallVectorImpl<MCFixup> &Fixups) const
115{
116
117  // Non-pseudo instructions that get changed for direct object
118  // only based on operand values.
119  // If this list of instructions get much longer we will move
120  // the check to a function call. Until then, this is more efficient.
121  MCInst TmpInst = MI;
122  switch (MI.getOpcode()) {
123  // If shift amount is >= 32 it the inst needs to be lowered further
124  case Mips::DSLL:
125  case Mips::DSRL:
126  case Mips::DSRA:
127    Mips::LowerLargeShift(TmpInst);
128    break;
129    // Double extract instruction is chosen by pos and size operands
130  case Mips::DEXT:
131  case Mips::DINS:
132    Mips::LowerDextDins(TmpInst);
133  }
134
135  uint32_t Binary = getBinaryCodeForInstr(TmpInst, Fixups);
136
137  // Check for unimplemented opcodes.
138  // Unfortunately in MIPS both NOP and SLL will come in with Binary == 0
139  // so we have to special check for them.
140  unsigned Opcode = TmpInst.getOpcode();
141  if ((Opcode != Mips::NOP) && (Opcode != Mips::SLL) && !Binary)
142    llvm_unreachable("unimplemented opcode in EncodeInstruction()");
143
144  const MCInstrDesc &Desc = MCII.get(TmpInst.getOpcode());
145
146  // Get byte count of instruction
147  unsigned Size = Desc.getSize();
148  if (!Size)
149    llvm_unreachable("Desc.getSize() returns 0");
150
151  EmitInstruction(Binary, Size, OS);
152}
153
154/// getBranchTargetOpValue - Return binary encoding of the branch
155/// target operand. If the machine operand requires relocation,
156/// record the relocation and return zero.
157unsigned MipsMCCodeEmitter::
158getBranchTargetOpValue(const MCInst &MI, unsigned OpNo,
159                       SmallVectorImpl<MCFixup> &Fixups) const {
160
161  const MCOperand &MO = MI.getOperand(OpNo);
162
163  // If the destination is an immediate, divide by 4.
164  if (MO.isImm()) return MO.getImm() >> 2;
165
166  assert(MO.isExpr() &&
167         "getBranchTargetOpValue expects only expressions or immediates");
168
169  const MCExpr *Expr = MO.getExpr();
170  Fixups.push_back(MCFixup::Create(0, Expr,
171                                   MCFixupKind(Mips::fixup_Mips_PC16)));
172  return 0;
173}
174
175/// getJumpTargetOpValue - Return binary encoding of the jump
176/// target operand. If the machine operand requires relocation,
177/// record the relocation and return zero.
178unsigned MipsMCCodeEmitter::
179getJumpTargetOpValue(const MCInst &MI, unsigned OpNo,
180                     SmallVectorImpl<MCFixup> &Fixups) const {
181
182  const MCOperand &MO = MI.getOperand(OpNo);
183  // If the destination is an immediate, divide by 4.
184  if (MO.isImm()) return MO.getImm()>>2;
185
186  assert(MO.isExpr() &&
187         "getJumpTargetOpValue expects only expressions or an immediate");
188
189  const MCExpr *Expr = MO.getExpr();
190  Fixups.push_back(MCFixup::Create(0, Expr,
191                                   MCFixupKind(Mips::fixup_Mips_26)));
192  return 0;
193}
194
195/// getMachineOpValue - Return binary encoding of operand. If the machine
196/// operand requires relocation, record the relocation and return zero.
197unsigned MipsMCCodeEmitter::
198getMachineOpValue(const MCInst &MI, const MCOperand &MO,
199                  SmallVectorImpl<MCFixup> &Fixups) const {
200  if (MO.isReg()) {
201    unsigned Reg = MO.getReg();
202    unsigned RegNo = Ctx.getRegisterInfo().getEncodingValue(Reg);
203    return RegNo;
204  } else if (MO.isImm()) {
205    return static_cast<unsigned>(MO.getImm());
206  } else if (MO.isFPImm()) {
207    return static_cast<unsigned>(APFloat(MO.getFPImm())
208        .bitcastToAPInt().getHiBits(32).getLimitedValue());
209  }
210
211  // MO must be an Expr.
212  assert(MO.isExpr());
213
214  const MCExpr *Expr = MO.getExpr();
215  MCExpr::ExprKind Kind = Expr->getKind();
216
217  if (Kind == MCExpr::Binary) {
218    Expr = static_cast<const MCBinaryExpr*>(Expr)->getLHS();
219    Kind = Expr->getKind();
220  }
221
222  assert (Kind == MCExpr::SymbolRef);
223
224  Mips::Fixups FixupKind = Mips::Fixups(0);
225
226  switch(cast<MCSymbolRefExpr>(Expr)->getKind()) {
227  default: llvm_unreachable("Unknown fixup kind!");
228    break;
229  case MCSymbolRefExpr::VK_Mips_GPOFF_HI :
230    FixupKind = Mips::fixup_Mips_GPOFF_HI;
231    break;
232  case MCSymbolRefExpr::VK_Mips_GPOFF_LO :
233    FixupKind = Mips::fixup_Mips_GPOFF_LO;
234    break;
235  case MCSymbolRefExpr::VK_Mips_GOT_PAGE :
236    FixupKind = Mips::fixup_Mips_GOT_PAGE;
237    break;
238  case MCSymbolRefExpr::VK_Mips_GOT_OFST :
239    FixupKind = Mips::fixup_Mips_GOT_OFST;
240    break;
241  case MCSymbolRefExpr::VK_Mips_GOT_DISP :
242    FixupKind = Mips::fixup_Mips_GOT_DISP;
243    break;
244  case MCSymbolRefExpr::VK_Mips_GPREL:
245    FixupKind = Mips::fixup_Mips_GPREL16;
246    break;
247  case MCSymbolRefExpr::VK_Mips_GOT_CALL:
248    FixupKind = Mips::fixup_Mips_CALL16;
249    break;
250  case MCSymbolRefExpr::VK_Mips_GOT16:
251    FixupKind = Mips::fixup_Mips_GOT_Global;
252    break;
253  case MCSymbolRefExpr::VK_Mips_GOT:
254    FixupKind = Mips::fixup_Mips_GOT_Local;
255    break;
256  case MCSymbolRefExpr::VK_Mips_ABS_HI:
257    FixupKind = Mips::fixup_Mips_HI16;
258    break;
259  case MCSymbolRefExpr::VK_Mips_ABS_LO:
260    FixupKind = Mips::fixup_Mips_LO16;
261    break;
262  case MCSymbolRefExpr::VK_Mips_TLSGD:
263    FixupKind = Mips::fixup_Mips_TLSGD;
264    break;
265  case MCSymbolRefExpr::VK_Mips_TLSLDM:
266    FixupKind = Mips::fixup_Mips_TLSLDM;
267    break;
268  case MCSymbolRefExpr::VK_Mips_DTPREL_HI:
269    FixupKind = Mips::fixup_Mips_DTPREL_HI;
270    break;
271  case MCSymbolRefExpr::VK_Mips_DTPREL_LO:
272    FixupKind = Mips::fixup_Mips_DTPREL_LO;
273    break;
274  case MCSymbolRefExpr::VK_Mips_GOTTPREL:
275    FixupKind = Mips::fixup_Mips_GOTTPREL;
276    break;
277  case MCSymbolRefExpr::VK_Mips_TPREL_HI:
278    FixupKind = Mips::fixup_Mips_TPREL_HI;
279    break;
280  case MCSymbolRefExpr::VK_Mips_TPREL_LO:
281    FixupKind = Mips::fixup_Mips_TPREL_LO;
282    break;
283  case MCSymbolRefExpr::VK_Mips_HIGHER:
284    FixupKind = Mips::fixup_Mips_HIGHER;
285    break;
286  case MCSymbolRefExpr::VK_Mips_HIGHEST:
287    FixupKind = Mips::fixup_Mips_HIGHEST;
288    break;
289  case MCSymbolRefExpr::VK_Mips_GOT_HI16:
290    FixupKind = Mips::fixup_Mips_GOT_HI16;
291    break;
292  case MCSymbolRefExpr::VK_Mips_GOT_LO16:
293    FixupKind = Mips::fixup_Mips_GOT_LO16;
294    break;
295  case MCSymbolRefExpr::VK_Mips_CALL_HI16:
296    FixupKind = Mips::fixup_Mips_CALL_HI16;
297    break;
298  case MCSymbolRefExpr::VK_Mips_CALL_LO16:
299    FixupKind = Mips::fixup_Mips_CALL_LO16;
300    break;
301  } // switch
302
303  Fixups.push_back(MCFixup::Create(0, MO.getExpr(), MCFixupKind(FixupKind)));
304
305  // All of the information is in the fixup.
306  return 0;
307}
308
309/// getMemEncoding - Return binary encoding of memory related operand.
310/// If the offset operand requires relocation, record the relocation.
311unsigned
312MipsMCCodeEmitter::getMemEncoding(const MCInst &MI, unsigned OpNo,
313                                  SmallVectorImpl<MCFixup> &Fixups) const {
314  // Base register is encoded in bits 20-16, offset is encoded in bits 15-0.
315  assert(MI.getOperand(OpNo).isReg());
316  unsigned RegBits = getMachineOpValue(MI, MI.getOperand(OpNo),Fixups) << 16;
317  unsigned OffBits = getMachineOpValue(MI, MI.getOperand(OpNo+1), Fixups);
318
319  return (OffBits & 0xFFFF) | RegBits;
320}
321
322unsigned
323MipsMCCodeEmitter::getSizeExtEncoding(const MCInst &MI, unsigned OpNo,
324                                      SmallVectorImpl<MCFixup> &Fixups) const {
325  assert(MI.getOperand(OpNo).isImm());
326  unsigned SizeEncoding = getMachineOpValue(MI, MI.getOperand(OpNo), Fixups);
327  return SizeEncoding - 1;
328}
329
330// FIXME: should be called getMSBEncoding
331//
332unsigned
333MipsMCCodeEmitter::getSizeInsEncoding(const MCInst &MI, unsigned OpNo,
334                                      SmallVectorImpl<MCFixup> &Fixups) const {
335  assert(MI.getOperand(OpNo-1).isImm());
336  assert(MI.getOperand(OpNo).isImm());
337  unsigned Position = getMachineOpValue(MI, MI.getOperand(OpNo-1), Fixups);
338  unsigned Size = getMachineOpValue(MI, MI.getOperand(OpNo), Fixups);
339
340  return Position + Size - 1;
341}
342
343#include "MipsGenMCCodeEmitter.inc"
344
345