xref: /freebsd/contrib/llvm-project/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCCodeEmitter.cpp (revision 770cf0a5f02dc8983a89c6568d741fbc25baa999)
1 //===-- PPCMCCodeEmitter.cpp - Convert PPC code to machine code -----------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements the PPCMCCodeEmitter class.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "PPCMCCodeEmitter.h"
14 #include "MCTargetDesc/PPCFixupKinds.h"
15 #include "PPCMCAsmInfo.h"
16 #include "PPCMCTargetDesc.h"
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/ADT/Statistic.h"
19 #include "llvm/MC/MCExpr.h"
20 #include "llvm/MC/MCFixup.h"
21 #include "llvm/MC/MCInstrDesc.h"
22 #include "llvm/MC/MCRegisterInfo.h"
23 #include "llvm/Support/Casting.h"
24 #include "llvm/Support/EndianStream.h"
25 #include "llvm/Support/ErrorHandling.h"
26 #include "llvm/Support/MathExtras.h"
27 #include "llvm/TargetParser/Triple.h"
28 #include <cassert>
29 #include <cstdint>
30 
31 using namespace llvm;
32 
33 #define DEBUG_TYPE "mccodeemitter"
34 
35 STATISTIC(MCNumEmitted, "Number of MC instructions emitted");
36 
37 MCCodeEmitter *llvm::createPPCMCCodeEmitter(const MCInstrInfo &MCII,
38                                             MCContext &Ctx) {
39   return new PPCMCCodeEmitter(MCII, Ctx);
40 }
41 
42 static void addFixup(SmallVectorImpl<MCFixup> &Fixups, uint32_t Offset,
43                      const MCExpr *Value, uint16_t Kind) {
44   bool PCRel = false;
45   switch (Kind) {
46   case PPC::fixup_ppc_br24:
47   case PPC::fixup_ppc_br24_notoc:
48   case PPC::fixup_ppc_brcond14:
49   case PPC::fixup_ppc_pcrel34:
50     PCRel = true;
51   }
52   Fixups.push_back(MCFixup::create(Offset, Value, Kind, PCRel));
53 }
54 
55 unsigned PPCMCCodeEmitter::
56 getDirectBrEncoding(const MCInst &MI, unsigned OpNo,
57                     SmallVectorImpl<MCFixup> &Fixups,
58                     const MCSubtargetInfo &STI) const {
59   const MCOperand &MO = MI.getOperand(OpNo);
60 
61   if (MO.isReg() || MO.isImm())
62     return getMachineOpValue(MI, MO, Fixups, STI);
63 
64   // Add a fixup for the branch target.
65   addFixup(
66       Fixups, 0, MO.getExpr(),
67       (isNoTOCCallInstr(MI) ? PPC::fixup_ppc_br24_notoc : PPC::fixup_ppc_br24));
68   return 0;
69 }
70 
71 /// Check if Opcode corresponds to a call instruction that should be marked
72 /// with the NOTOC relocation.
73 bool PPCMCCodeEmitter::isNoTOCCallInstr(const MCInst &MI) const {
74   unsigned Opcode = MI.getOpcode();
75   if (!MCII.get(Opcode).isCall())
76     return false;
77 
78   switch (Opcode) {
79   default:
80 #ifndef NDEBUG
81     llvm_unreachable("Unknown call opcode");
82 #endif
83     return false;
84   case PPC::BL8_NOTOC:
85   case PPC::BL8_NOTOC_TLS:
86   case PPC::BL8_NOTOC_RM:
87     return true;
88 #ifndef NDEBUG
89   case PPC::BL8:
90   case PPC::BL:
91   case PPC::BL8_TLS:
92   case PPC::BL_TLS:
93   case PPC::BLA8:
94   case PPC::BLA:
95   case PPC::BCCL:
96   case PPC::BCCLA:
97   case PPC::BCL:
98   case PPC::BCLn:
99   case PPC::BL8_NOP:
100   case PPC::BL_NOP:
101   case PPC::BL8_NOP_TLS:
102   case PPC::BLA8_NOP:
103   case PPC::BCTRL8:
104   case PPC::BCTRL:
105   case PPC::BCCCTRL8:
106   case PPC::BCCCTRL:
107   case PPC::BCCTRL8:
108   case PPC::BCCTRL:
109   case PPC::BCCTRL8n:
110   case PPC::BCCTRLn:
111   case PPC::BL8_RM:
112   case PPC::BLA8_RM:
113   case PPC::BL8_NOP_RM:
114   case PPC::BLA8_NOP_RM:
115   case PPC::BCTRL8_RM:
116   case PPC::BCTRL8_LDinto_toc:
117   case PPC::BCTRL8_LDinto_toc_RM:
118   case PPC::BL8_TLS_:
119   case PPC::TCRETURNdi8:
120   case PPC::TCRETURNai8:
121   case PPC::TCRETURNri8:
122   case PPC::TAILBCTR8:
123   case PPC::TAILB8:
124   case PPC::TAILBA8:
125   case PPC::BCLalways:
126   case PPC::BLRL:
127   case PPC::BCCLRL:
128   case PPC::BCLRL:
129   case PPC::BCLRLn:
130   case PPC::BDZL:
131   case PPC::BDNZL:
132   case PPC::BDZLA:
133   case PPC::BDNZLA:
134   case PPC::BDZLp:
135   case PPC::BDNZLp:
136   case PPC::BDZLAp:
137   case PPC::BDNZLAp:
138   case PPC::BDZLm:
139   case PPC::BDNZLm:
140   case PPC::BDZLAm:
141   case PPC::BDNZLAm:
142   case PPC::BDZLRL:
143   case PPC::BDNZLRL:
144   case PPC::BDZLRLp:
145   case PPC::BDNZLRLp:
146   case PPC::BDZLRLm:
147   case PPC::BDNZLRLm:
148   case PPC::BL_RM:
149   case PPC::BLA_RM:
150   case PPC::BL_NOP_RM:
151   case PPC::BCTRL_RM:
152   case PPC::TCRETURNdi:
153   case PPC::TCRETURNai:
154   case PPC::TCRETURNri:
155   case PPC::BCTRL_LWZinto_toc:
156   case PPC::BCTRL_LWZinto_toc_RM:
157   case PPC::TAILBCTR:
158   case PPC::TAILB:
159   case PPC::TAILBA:
160     return false;
161 #endif
162   }
163 }
164 
165 unsigned PPCMCCodeEmitter::getCondBrEncoding(const MCInst &MI, unsigned OpNo,
166                                      SmallVectorImpl<MCFixup> &Fixups,
167                                      const MCSubtargetInfo &STI) const {
168   const MCOperand &MO = MI.getOperand(OpNo);
169   if (MO.isReg() || MO.isImm()) return getMachineOpValue(MI, MO, Fixups, STI);
170 
171   // Add a fixup for the branch target.
172   addFixup(Fixups, 0, MO.getExpr(), PPC::fixup_ppc_brcond14);
173   return 0;
174 }
175 
176 unsigned PPCMCCodeEmitter::
177 getAbsDirectBrEncoding(const MCInst &MI, unsigned OpNo,
178                        SmallVectorImpl<MCFixup> &Fixups,
179                        const MCSubtargetInfo &STI) const {
180   const MCOperand &MO = MI.getOperand(OpNo);
181   if (MO.isReg() || MO.isImm()) return getMachineOpValue(MI, MO, Fixups, STI);
182 
183   // Add a fixup for the branch target.
184   addFixup(Fixups, 0, MO.getExpr(), PPC::fixup_ppc_br24abs);
185   return 0;
186 }
187 
188 unsigned PPCMCCodeEmitter::
189 getAbsCondBrEncoding(const MCInst &MI, unsigned OpNo,
190                      SmallVectorImpl<MCFixup> &Fixups,
191                      const MCSubtargetInfo &STI) const {
192   const MCOperand &MO = MI.getOperand(OpNo);
193   if (MO.isReg() || MO.isImm()) return getMachineOpValue(MI, MO, Fixups, STI);
194 
195   // Add a fixup for the branch target.
196   addFixup(Fixups, 0, MO.getExpr(), PPC::fixup_ppc_brcond14abs);
197   return 0;
198 }
199 
200 unsigned
201 PPCMCCodeEmitter::getVSRpEvenEncoding(const MCInst &MI, unsigned OpNo,
202                                       SmallVectorImpl<MCFixup> &Fixups,
203                                       const MCSubtargetInfo &STI) const {
204   assert(MI.getOperand(OpNo).isReg() && "Operand should be a register");
205   unsigned RegBits = getMachineOpValue(MI, MI.getOperand(OpNo), Fixups, STI)
206                      << 1;
207   return RegBits;
208 }
209 
210 unsigned PPCMCCodeEmitter::getImm16Encoding(const MCInst &MI, unsigned OpNo,
211                                        SmallVectorImpl<MCFixup> &Fixups,
212                                        const MCSubtargetInfo &STI) const {
213   const MCOperand &MO = MI.getOperand(OpNo);
214   if (MO.isReg() || MO.isImm()) return getMachineOpValue(MI, MO, Fixups, STI);
215 
216   // Add a fixup for the immediate field.
217   addFixup(Fixups, IsLittleEndian ? 0 : 2, MO.getExpr(), PPC::fixup_ppc_half16);
218   return 0;
219 }
220 
221 uint64_t PPCMCCodeEmitter::getImm34Encoding(const MCInst &MI, unsigned OpNo,
222                                             SmallVectorImpl<MCFixup> &Fixups,
223                                             const MCSubtargetInfo &STI,
224                                             MCFixupKind Fixup) const {
225   const MCOperand &MO = MI.getOperand(OpNo);
226   assert(!MO.isReg() && "Not expecting a register for this operand.");
227   if (MO.isImm())
228     return getMachineOpValue(MI, MO, Fixups, STI);
229 
230   // Add a fixup for the immediate field.
231   addFixup(Fixups, 0, MO.getExpr(), Fixup);
232   return 0;
233 }
234 
235 uint64_t
236 PPCMCCodeEmitter::getImm34EncodingNoPCRel(const MCInst &MI, unsigned OpNo,
237                                           SmallVectorImpl<MCFixup> &Fixups,
238                                           const MCSubtargetInfo &STI) const {
239   return getImm34Encoding(MI, OpNo, Fixups, STI, PPC::fixup_ppc_imm34);
240 }
241 
242 uint64_t
243 PPCMCCodeEmitter::getImm34EncodingPCRel(const MCInst &MI, unsigned OpNo,
244                                         SmallVectorImpl<MCFixup> &Fixups,
245                                         const MCSubtargetInfo &STI) const {
246   return getImm34Encoding(MI, OpNo, Fixups, STI, PPC::fixup_ppc_pcrel34);
247 }
248 
249 unsigned PPCMCCodeEmitter::getDispRIEncoding(const MCInst &MI, unsigned OpNo,
250                                              SmallVectorImpl<MCFixup> &Fixups,
251                                              const MCSubtargetInfo &STI) const {
252   const MCOperand &MO = MI.getOperand(OpNo);
253   if (MO.isImm())
254     return getMachineOpValue(MI, MO, Fixups, STI) & 0xFFFF;
255 
256   // Add a fixup for the displacement field.
257   addFixup(Fixups, IsLittleEndian ? 0 : 2, MO.getExpr(), PPC::fixup_ppc_half16);
258   return 0;
259 }
260 
261 unsigned
262 PPCMCCodeEmitter::getDispRIXEncoding(const MCInst &MI, unsigned OpNo,
263                                      SmallVectorImpl<MCFixup> &Fixups,
264                                      const MCSubtargetInfo &STI) const {
265   const MCOperand &MO = MI.getOperand(OpNo);
266   if (MO.isImm())
267     return ((getMachineOpValue(MI, MO, Fixups, STI) >> 2) & 0x3FFF);
268 
269   // Add a fixup for the displacement field.
270   addFixup(Fixups, IsLittleEndian ? 0 : 2, MO.getExpr(),
271            PPC::fixup_ppc_half16ds);
272   return 0;
273 }
274 
275 unsigned
276 PPCMCCodeEmitter::getDispRIX16Encoding(const MCInst &MI, unsigned OpNo,
277                                        SmallVectorImpl<MCFixup> &Fixups,
278                                        const MCSubtargetInfo &STI) const {
279   const MCOperand &MO = MI.getOperand(OpNo);
280   if (MO.isImm()) {
281     assert(!(MO.getImm() % 16) &&
282            "Expecting an immediate that is a multiple of 16");
283     return ((getMachineOpValue(MI, MO, Fixups, STI) >> 4) & 0xFFF);
284   }
285 
286   // Otherwise add a fixup for the displacement field.
287   addFixup(Fixups, IsLittleEndian ? 0 : 2, MO.getExpr(),
288            PPC::fixup_ppc_half16dq);
289   return 0;
290 }
291 
292 unsigned
293 PPCMCCodeEmitter::getDispRIHashEncoding(const MCInst &MI, unsigned OpNo,
294                                         SmallVectorImpl<MCFixup> &Fixups,
295                                         const MCSubtargetInfo &STI) const {
296   // Encode imm for the hash load/store to stack for the ROP Protection
297   // instructions.
298   const MCOperand &MO = MI.getOperand(OpNo);
299 
300   assert(MO.isImm() && "Expecting an immediate operand.");
301   assert(!(MO.getImm() % 8) && "Expecting offset to be 8 byte aligned.");
302 
303   unsigned DX = (MO.getImm() >> 3) & 0x3F;
304   return DX;
305 }
306 
307 uint64_t
308 PPCMCCodeEmitter::getDispRI34PCRelEncoding(const MCInst &MI, unsigned OpNo,
309                                            SmallVectorImpl<MCFixup> &Fixups,
310                                            const MCSubtargetInfo &STI) const {
311   // Encode the displacement part of pc-relative memri34, which is an imm34.
312   // The 34 bit immediate can fall into one of three cases:
313   // 1) It is a relocation to be filled in by the linker represented as:
314   //    (MCExpr::SymbolRef)
315   // 2) It is a relocation + SignedOffset represented as:
316   //    (MCExpr::Binary(MCExpr::SymbolRef + MCExpr::Constant))
317   // 3) It is a known value at compile time.
318 
319   // If this is not a MCExpr then we are in case 3) and we are dealing with
320   // a value known at compile time, not a relocation.
321   const MCOperand &MO = MI.getOperand(OpNo);
322   if (!MO.isExpr())
323     return (getMachineOpValue(MI, MO, Fixups, STI)) & 0x3FFFFFFFFUL;
324 
325   // At this point in the function it is known that MO is of type MCExpr.
326   // Therefore we are dealing with either case 1) a symbol ref or
327   // case 2) a symbol ref plus a constant.
328   const MCExpr *Expr = MO.getExpr();
329   switch (Expr->getKind()) {
330   default:
331     llvm_unreachable("Unsupported MCExpr for getMemRI34PCRelEncoding.");
332   case MCExpr::SymbolRef: {
333     // Relocation alone.
334     const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(Expr);
335     (void)SRE;
336     // Currently these are the only valid PCRelative Relocations.
337     assert(is_contained({PPC::S_PCREL, PPC::S_GOT_PCREL, PPC::S_GOT_TLSGD_PCREL,
338                          PPC::S_GOT_TLSLD_PCREL, PPC::S_GOT_TPREL_PCREL},
339                         SRE->getSpecifier()) &&
340            "specifier must be S_PCREL, S_GOT_PCREL, S_GOT_TLSGD_PCREL, "
341            "S_GOT_TLSLD_PCREL, or S_GOT_TPREL_PCREL");
342     // Generate the fixup for the relocation.
343     addFixup(Fixups, 0, Expr, PPC::fixup_ppc_pcrel34);
344     // Put zero in the location of the immediate. The linker will fill in the
345     // correct value based on the relocation.
346     return 0;
347   }
348   case MCExpr::Binary: {
349     // Relocation plus some offset.
350     const MCBinaryExpr *BE = cast<MCBinaryExpr>(Expr);
351     assert(BE->getOpcode() == MCBinaryExpr::Add &&
352            "Binary expression opcode must be an add.");
353 
354     const MCExpr *LHS = BE->getLHS();
355     const MCExpr *RHS = BE->getRHS();
356 
357     // Need to check in both directions. Reloc+Offset and Offset+Reloc.
358     if (LHS->getKind() != MCExpr::SymbolRef)
359       std::swap(LHS, RHS);
360 
361     if (LHS->getKind() != MCExpr::SymbolRef ||
362         RHS->getKind() != MCExpr::Constant)
363       llvm_unreachable("Expecting to have one constant and one relocation.");
364 
365     const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(LHS);
366     (void)SRE;
367     assert(isInt<34>(cast<MCConstantExpr>(RHS)->getValue()) &&
368            "Value must fit in 34 bits.");
369 
370     // Currently these are the only valid PCRelative Relocations.
371     assert((getSpecifier(SRE) == PPC::S_PCREL ||
372             getSpecifier(SRE) == PPC::S_GOT_PCREL) &&
373            "VariantKind must be VK_PCREL or VK_GOT_PCREL");
374     // Generate the fixup for the relocation.
375     addFixup(Fixups, 0, Expr, PPC::fixup_ppc_pcrel34);
376     // Put zero in the location of the immediate. The linker will fill in the
377     // correct value based on the relocation.
378     return 0;
379     }
380   }
381 }
382 
383 uint64_t
384 PPCMCCodeEmitter::getDispRI34Encoding(const MCInst &MI, unsigned OpNo,
385                                       SmallVectorImpl<MCFixup> &Fixups,
386                                       const MCSubtargetInfo &STI) const {
387   // Encode the displacement part of a memri34.
388   const MCOperand &MO = MI.getOperand(OpNo);
389   return (getMachineOpValue(MI, MO, Fixups, STI)) & 0x3FFFFFFFFUL;
390 }
391 
392 unsigned
393 PPCMCCodeEmitter::getDispSPE8Encoding(const MCInst &MI, unsigned OpNo,
394                                       SmallVectorImpl<MCFixup> &Fixups,
395                                       const MCSubtargetInfo &STI) const {
396   // Encode imm as a dispSPE8, which has the low 5-bits of (imm / 8).
397   const MCOperand &MO = MI.getOperand(OpNo);
398   assert(MO.isImm());
399   return getMachineOpValue(MI, MO, Fixups, STI) >> 3;
400 }
401 
402 unsigned
403 PPCMCCodeEmitter::getDispSPE4Encoding(const MCInst &MI, unsigned OpNo,
404                                       SmallVectorImpl<MCFixup> &Fixups,
405                                       const MCSubtargetInfo &STI) const {
406   // Encode imm as a dispSPE8, which has the low 5-bits of (imm / 4).
407   const MCOperand &MO = MI.getOperand(OpNo);
408   assert(MO.isImm());
409   return getMachineOpValue(MI, MO, Fixups, STI) >> 2;
410 }
411 
412 unsigned
413 PPCMCCodeEmitter::getDispSPE2Encoding(const MCInst &MI, unsigned OpNo,
414                                       SmallVectorImpl<MCFixup> &Fixups,
415                                       const MCSubtargetInfo &STI) const {
416   // Encode imm as a dispSPE8, which has the low 5-bits of (imm / 2).
417   const MCOperand &MO = MI.getOperand(OpNo);
418   assert(MO.isImm());
419   return getMachineOpValue(MI, MO, Fixups, STI) >> 1;
420 }
421 
422 unsigned PPCMCCodeEmitter::getTLSRegEncoding(const MCInst &MI, unsigned OpNo,
423                                        SmallVectorImpl<MCFixup> &Fixups,
424                                        const MCSubtargetInfo &STI) const {
425   const MCOperand &MO = MI.getOperand(OpNo);
426   if (MO.isReg()) return getMachineOpValue(MI, MO, Fixups, STI);
427 
428   // Add a fixup for the TLS register, which simply provides a relocation
429   // hint to the linker that this statement is part of a relocation sequence.
430   // Return the thread-pointer register's encoding. Add a one byte displacement
431   // if using PC relative memops.
432   const MCExpr *Expr = MO.getExpr();
433   const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(Expr);
434   bool IsPCRel = getSpecifier(SRE) == PPC::S_TLS_PCREL;
435   addFixup(Fixups, IsPCRel ? 1 : 0, Expr, PPC::fixup_ppc_nofixup);
436   const Triple &TT = STI.getTargetTriple();
437   bool isPPC64 = TT.isPPC64();
438   return CTX.getRegisterInfo()->getEncodingValue(isPPC64 ? PPC::X13 : PPC::R2);
439 }
440 
441 unsigned PPCMCCodeEmitter::getTLSCallEncoding(const MCInst &MI, unsigned OpNo,
442                                        SmallVectorImpl<MCFixup> &Fixups,
443                                        const MCSubtargetInfo &STI) const {
444   // For special TLS calls, we need two fixups; one for the branch target
445   // (__tls_get_addr), which we create via getDirectBrEncoding as usual,
446   // and one for the TLSGD or TLSLD symbol, which is emitted here.
447   const MCOperand &MO = MI.getOperand(OpNo+1);
448   addFixup(Fixups, 0, MO.getExpr(), PPC::fixup_ppc_nofixup);
449   return getDirectBrEncoding(MI, OpNo, Fixups, STI);
450 }
451 
452 unsigned PPCMCCodeEmitter::
453 get_crbitm_encoding(const MCInst &MI, unsigned OpNo,
454                     SmallVectorImpl<MCFixup> &Fixups,
455                     const MCSubtargetInfo &STI) const {
456   const MCOperand &MO = MI.getOperand(OpNo);
457   assert((MI.getOpcode() == PPC::MTOCRF || MI.getOpcode() == PPC::MTOCRF8 ||
458           MI.getOpcode() == PPC::MFOCRF || MI.getOpcode() == PPC::MFOCRF8) &&
459          (MO.getReg() >= PPC::CR0 && MO.getReg() <= PPC::CR7));
460   return 0x80 >> CTX.getRegisterInfo()->getEncodingValue(MO.getReg());
461 }
462 
463 // Get the index for this operand in this instruction. This is needed for
464 // computing the register number in PPC::getRegNumForOperand() for
465 // any instructions that use a different numbering scheme for registers in
466 // different operands.
467 static unsigned getOpIdxForMO(const MCInst &MI, const MCOperand &MO) {
468   for (unsigned i = 0; i < MI.getNumOperands(); i++) {
469     const MCOperand &Op = MI.getOperand(i);
470     if (&Op == &MO)
471       return i;
472   }
473   llvm_unreachable("This operand is not part of this instruction");
474   return ~0U; // Silence any warnings about no return.
475 }
476 
477 uint64_t PPCMCCodeEmitter::
478 getMachineOpValue(const MCInst &MI, const MCOperand &MO,
479                   SmallVectorImpl<MCFixup> &Fixups,
480                   const MCSubtargetInfo &STI) const {
481   if (MO.isReg()) {
482     // MTOCRF/MFOCRF should go through get_crbitm_encoding for the CR operand.
483     // The GPR operand should come through here though.
484     assert((MI.getOpcode() != PPC::MTOCRF && MI.getOpcode() != PPC::MTOCRF8 &&
485             MI.getOpcode() != PPC::MFOCRF && MI.getOpcode() != PPC::MFOCRF8) ||
486            MO.getReg() < PPC::CR0 || MO.getReg() > PPC::CR7);
487     unsigned OpNo = getOpIdxForMO(MI, MO);
488     MCRegister Reg =
489         PPC::getRegNumForOperand(MCII.get(MI.getOpcode()), MO.getReg(), OpNo);
490     return CTX.getRegisterInfo()->getEncodingValue(Reg);
491   }
492 
493   assert(MO.isImm() &&
494          "Relocation required in an instruction that we cannot encode!");
495   return MO.getImm();
496 }
497 
498 void PPCMCCodeEmitter::encodeInstruction(const MCInst &MI,
499                                          SmallVectorImpl<char> &CB,
500                                          SmallVectorImpl<MCFixup> &Fixups,
501                                          const MCSubtargetInfo &STI) const {
502   uint64_t Bits = getBinaryCodeForInstr(MI, Fixups, STI);
503 
504   // Output the constant in big/little endian byte order.
505   unsigned Size = getInstSizeInBytes(MI);
506   llvm::endianness E =
507       IsLittleEndian ? llvm::endianness::little : llvm::endianness::big;
508   switch (Size) {
509   case 0:
510     break;
511   case 4:
512     support::endian::write<uint32_t>(CB, Bits, E);
513     break;
514   case 8:
515     // If we emit a pair of instructions, the first one is
516     // always in the top 32 bits, even on little-endian.
517     support::endian::write<uint32_t>(CB, Bits >> 32, E);
518     support::endian::write<uint32_t>(CB, Bits, E);
519     break;
520   default:
521     llvm_unreachable("Invalid instruction size");
522   }
523 
524   ++MCNumEmitted; // Keep track of the # of mi's emitted.
525 }
526 
527 // Get the number of bytes used to encode the given MCInst.
528 unsigned PPCMCCodeEmitter::getInstSizeInBytes(const MCInst &MI) const {
529   unsigned Opcode = MI.getOpcode();
530   const MCInstrDesc &Desc = MCII.get(Opcode);
531   return Desc.getSize();
532 }
533 
534 bool PPCMCCodeEmitter::isPrefixedInstruction(const MCInst &MI) const {
535   return MCII.get(MI.getOpcode()).TSFlags & PPCII::Prefixed;
536 }
537 
538 #include "PPCGenMCCodeEmitter.inc"
539