1 //===-- SIMCCodeEmitter.cpp - SI Code Emitter -----------------------------===//
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 /// \file
10 /// The SI code emitter produces machine code that can be executed
11 /// directly on the GPU device.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "MCTargetDesc/AMDGPUFixupKinds.h"
16 #include "MCTargetDesc/AMDGPUMCCodeEmitter.h"
17 #include "MCTargetDesc/AMDGPUMCTargetDesc.h"
18 #include "SIDefines.h"
19 #include "Utils/AMDGPUBaseInfo.h"
20 #include "llvm/MC/MCContext.h"
21 #include "llvm/MC/MCExpr.h"
22 #include "llvm/MC/MCInstrInfo.h"
23 #include "llvm/MC/MCRegisterInfo.h"
24 #include "llvm/MC/MCSubtargetInfo.h"
25 #include "llvm/MC/SubtargetFeature.h"
26 #include "llvm/Support/Casting.h"
27 
28 using namespace llvm;
29 
30 namespace {
31 
32 class SIMCCodeEmitter : public  AMDGPUMCCodeEmitter {
33   const MCRegisterInfo &MRI;
34 
35   /// Encode an fp or int literal
36   uint32_t getLitEncoding(const MCOperand &MO, const MCOperandInfo &OpInfo,
37                           const MCSubtargetInfo &STI) const;
38 
39 public:
40   SIMCCodeEmitter(const MCInstrInfo &mcii, const MCRegisterInfo &mri,
41                   MCContext &ctx)
42       : AMDGPUMCCodeEmitter(mcii), MRI(mri) {}
43   SIMCCodeEmitter(const SIMCCodeEmitter &) = delete;
44   SIMCCodeEmitter &operator=(const SIMCCodeEmitter &) = delete;
45 
46   /// Encode the instruction and write it to the OS.
47   void encodeInstruction(const MCInst &MI, raw_ostream &OS,
48                          SmallVectorImpl<MCFixup> &Fixups,
49                          const MCSubtargetInfo &STI) const override;
50 
51   /// \returns the encoding for an MCOperand.
52   uint64_t getMachineOpValue(const MCInst &MI, const MCOperand &MO,
53                              SmallVectorImpl<MCFixup> &Fixups,
54                              const MCSubtargetInfo &STI) const override;
55 
56   /// Use a fixup to encode the simm16 field for SOPP branch
57   ///        instructions.
58   unsigned getSOPPBrEncoding(const MCInst &MI, unsigned OpNo,
59                              SmallVectorImpl<MCFixup> &Fixups,
60                              const MCSubtargetInfo &STI) const override;
61 
62   unsigned getSMEMOffsetEncoding(const MCInst &MI, unsigned OpNo,
63                                  SmallVectorImpl<MCFixup> &Fixups,
64                                  const MCSubtargetInfo &STI) const override;
65 
66   unsigned getSDWASrcEncoding(const MCInst &MI, unsigned OpNo,
67                               SmallVectorImpl<MCFixup> &Fixups,
68                               const MCSubtargetInfo &STI) const override;
69 
70   unsigned getSDWAVopcDstEncoding(const MCInst &MI, unsigned OpNo,
71                                   SmallVectorImpl<MCFixup> &Fixups,
72                                   const MCSubtargetInfo &STI) const override;
73 
74   unsigned getAVOperandEncoding(const MCInst &MI, unsigned OpNo,
75                                 SmallVectorImpl<MCFixup> &Fixups,
76                                 const MCSubtargetInfo &STI) const override;
77 
78 private:
79   uint64_t getImplicitOpSelHiEncoding(int Opcode) const;
80 };
81 
82 } // end anonymous namespace
83 
84 MCCodeEmitter *llvm::createSIMCCodeEmitter(const MCInstrInfo &MCII,
85                                            const MCRegisterInfo &MRI,
86                                            MCContext &Ctx) {
87   return new SIMCCodeEmitter(MCII, MRI, Ctx);
88 }
89 
90 // Returns the encoding value to use if the given integer is an integer inline
91 // immediate value, or 0 if it is not.
92 template <typename IntTy>
93 static uint32_t getIntInlineImmEncoding(IntTy Imm) {
94   if (Imm >= 0 && Imm <= 64)
95     return 128 + Imm;
96 
97   if (Imm >= -16 && Imm <= -1)
98     return 192 + std::abs(Imm);
99 
100   return 0;
101 }
102 
103 static uint32_t getLit16IntEncoding(uint16_t Val, const MCSubtargetInfo &STI) {
104   uint16_t IntImm = getIntInlineImmEncoding(static_cast<int16_t>(Val));
105   return IntImm == 0 ? 255 : IntImm;
106 }
107 
108 static uint32_t getLit16Encoding(uint16_t Val, const MCSubtargetInfo &STI) {
109   uint16_t IntImm = getIntInlineImmEncoding(static_cast<int16_t>(Val));
110   if (IntImm != 0)
111     return IntImm;
112 
113   if (Val == 0x3800) // 0.5
114     return 240;
115 
116   if (Val == 0xB800) // -0.5
117     return 241;
118 
119   if (Val == 0x3C00) // 1.0
120     return 242;
121 
122   if (Val == 0xBC00) // -1.0
123     return 243;
124 
125   if (Val == 0x4000) // 2.0
126     return 244;
127 
128   if (Val == 0xC000) // -2.0
129     return 245;
130 
131   if (Val == 0x4400) // 4.0
132     return 246;
133 
134   if (Val == 0xC400) // -4.0
135     return 247;
136 
137   if (Val == 0x3118 && // 1.0 / (2.0 * pi)
138       STI.getFeatureBits()[AMDGPU::FeatureInv2PiInlineImm])
139     return 248;
140 
141   return 255;
142 }
143 
144 static uint32_t getLit32Encoding(uint32_t Val, const MCSubtargetInfo &STI) {
145   uint32_t IntImm = getIntInlineImmEncoding(static_cast<int32_t>(Val));
146   if (IntImm != 0)
147     return IntImm;
148 
149   if (Val == FloatToBits(0.5f))
150     return 240;
151 
152   if (Val == FloatToBits(-0.5f))
153     return 241;
154 
155   if (Val == FloatToBits(1.0f))
156     return 242;
157 
158   if (Val == FloatToBits(-1.0f))
159     return 243;
160 
161   if (Val == FloatToBits(2.0f))
162     return 244;
163 
164   if (Val == FloatToBits(-2.0f))
165     return 245;
166 
167   if (Val == FloatToBits(4.0f))
168     return 246;
169 
170   if (Val == FloatToBits(-4.0f))
171     return 247;
172 
173   if (Val == 0x3e22f983 && // 1.0 / (2.0 * pi)
174       STI.getFeatureBits()[AMDGPU::FeatureInv2PiInlineImm])
175     return 248;
176 
177   return 255;
178 }
179 
180 static uint32_t getLit64Encoding(uint64_t Val, const MCSubtargetInfo &STI) {
181   uint32_t IntImm = getIntInlineImmEncoding(static_cast<int64_t>(Val));
182   if (IntImm != 0)
183     return IntImm;
184 
185   if (Val == DoubleToBits(0.5))
186     return 240;
187 
188   if (Val == DoubleToBits(-0.5))
189     return 241;
190 
191   if (Val == DoubleToBits(1.0))
192     return 242;
193 
194   if (Val == DoubleToBits(-1.0))
195     return 243;
196 
197   if (Val == DoubleToBits(2.0))
198     return 244;
199 
200   if (Val == DoubleToBits(-2.0))
201     return 245;
202 
203   if (Val == DoubleToBits(4.0))
204     return 246;
205 
206   if (Val == DoubleToBits(-4.0))
207     return 247;
208 
209   if (Val == 0x3fc45f306dc9c882 && // 1.0 / (2.0 * pi)
210       STI.getFeatureBits()[AMDGPU::FeatureInv2PiInlineImm])
211     return 248;
212 
213   return 255;
214 }
215 
216 uint32_t SIMCCodeEmitter::getLitEncoding(const MCOperand &MO,
217                                          const MCOperandInfo &OpInfo,
218                                          const MCSubtargetInfo &STI) const {
219   int64_t Imm;
220   if (MO.isExpr()) {
221     const auto *C = dyn_cast<MCConstantExpr>(MO.getExpr());
222     if (!C)
223       return 255;
224 
225     Imm = C->getValue();
226   } else {
227 
228     assert(!MO.isDFPImm());
229 
230     if (!MO.isImm())
231       return ~0;
232 
233     Imm = MO.getImm();
234   }
235 
236   switch (OpInfo.OperandType) {
237   case AMDGPU::OPERAND_REG_IMM_INT32:
238   case AMDGPU::OPERAND_REG_IMM_FP32:
239   case AMDGPU::OPERAND_REG_IMM_FP32_DEFERRED:
240   case AMDGPU::OPERAND_REG_INLINE_C_INT32:
241   case AMDGPU::OPERAND_REG_INLINE_C_FP32:
242   case AMDGPU::OPERAND_REG_INLINE_AC_INT32:
243   case AMDGPU::OPERAND_REG_INLINE_AC_FP32:
244   case AMDGPU::OPERAND_REG_IMM_V2INT32:
245   case AMDGPU::OPERAND_REG_IMM_V2FP32:
246   case AMDGPU::OPERAND_REG_INLINE_C_V2INT32:
247   case AMDGPU::OPERAND_REG_INLINE_C_V2FP32:
248     return getLit32Encoding(static_cast<uint32_t>(Imm), STI);
249 
250   case AMDGPU::OPERAND_REG_IMM_INT64:
251   case AMDGPU::OPERAND_REG_IMM_FP64:
252   case AMDGPU::OPERAND_REG_INLINE_C_INT64:
253   case AMDGPU::OPERAND_REG_INLINE_C_FP64:
254   case AMDGPU::OPERAND_REG_INLINE_AC_FP64:
255     return getLit64Encoding(static_cast<uint64_t>(Imm), STI);
256 
257   case AMDGPU::OPERAND_REG_IMM_INT16:
258   case AMDGPU::OPERAND_REG_INLINE_C_INT16:
259   case AMDGPU::OPERAND_REG_INLINE_AC_INT16:
260     return getLit16IntEncoding(static_cast<uint16_t>(Imm), STI);
261   case AMDGPU::OPERAND_REG_IMM_FP16:
262   case AMDGPU::OPERAND_REG_IMM_FP16_DEFERRED:
263   case AMDGPU::OPERAND_REG_INLINE_C_FP16:
264   case AMDGPU::OPERAND_REG_INLINE_AC_FP16:
265     // FIXME Is this correct? What do inline immediates do on SI for f16 src
266     // which does not have f16 support?
267     return getLit16Encoding(static_cast<uint16_t>(Imm), STI);
268   case AMDGPU::OPERAND_REG_IMM_V2INT16:
269   case AMDGPU::OPERAND_REG_IMM_V2FP16: {
270     if (!isUInt<16>(Imm) && STI.getFeatureBits()[AMDGPU::FeatureVOP3Literal])
271       return getLit32Encoding(static_cast<uint32_t>(Imm), STI);
272     if (OpInfo.OperandType == AMDGPU::OPERAND_REG_IMM_V2FP16)
273       return getLit16Encoding(static_cast<uint16_t>(Imm), STI);
274     LLVM_FALLTHROUGH;
275   }
276   case AMDGPU::OPERAND_REG_INLINE_C_V2INT16:
277   case AMDGPU::OPERAND_REG_INLINE_AC_V2INT16:
278     return getLit16IntEncoding(static_cast<uint16_t>(Imm), STI);
279   case AMDGPU::OPERAND_REG_INLINE_C_V2FP16:
280   case AMDGPU::OPERAND_REG_INLINE_AC_V2FP16: {
281     uint16_t Lo16 = static_cast<uint16_t>(Imm);
282     uint32_t Encoding = getLit16Encoding(Lo16, STI);
283     return Encoding;
284   }
285   case AMDGPU::OPERAND_KIMM32:
286   case AMDGPU::OPERAND_KIMM16:
287     return MO.getImm();
288   default:
289     llvm_unreachable("invalid operand size");
290   }
291 }
292 
293 uint64_t SIMCCodeEmitter::getImplicitOpSelHiEncoding(int Opcode) const {
294   using namespace AMDGPU::VOP3PEncoding;
295   using namespace AMDGPU::OpName;
296 
297   if (AMDGPU::getNamedOperandIdx(Opcode, op_sel_hi) != -1) {
298     if (AMDGPU::getNamedOperandIdx(Opcode, src2) != -1)
299       return 0;
300     if (AMDGPU::getNamedOperandIdx(Opcode, src1) != -1)
301       return OP_SEL_HI_2;
302     if (AMDGPU::getNamedOperandIdx(Opcode, src0) != -1)
303       return OP_SEL_HI_1 | OP_SEL_HI_2;
304   }
305   return OP_SEL_HI_0 | OP_SEL_HI_1 | OP_SEL_HI_2;
306 }
307 
308 void SIMCCodeEmitter::encodeInstruction(const MCInst &MI, raw_ostream &OS,
309                                        SmallVectorImpl<MCFixup> &Fixups,
310                                        const MCSubtargetInfo &STI) const {
311   verifyInstructionPredicates(MI,
312                               computeAvailableFeatures(STI.getFeatureBits()));
313 
314   int Opcode = MI.getOpcode();
315   uint64_t Encoding = getBinaryCodeForInstr(MI, Fixups, STI);
316   const MCInstrDesc &Desc = MCII.get(Opcode);
317   unsigned bytes = Desc.getSize();
318 
319   // Set unused op_sel_hi bits to 1 for VOP3P and MAI instructions.
320   // Note that accvgpr_read/write are MAI, have src0, but do not use op_sel.
321   if ((Desc.TSFlags & SIInstrFlags::VOP3P) ||
322       Opcode == AMDGPU::V_ACCVGPR_READ_B32_vi ||
323       Opcode == AMDGPU::V_ACCVGPR_WRITE_B32_vi) {
324     Encoding |= getImplicitOpSelHiEncoding(Opcode);
325   }
326 
327   for (unsigned i = 0; i < bytes; i++) {
328     OS.write((uint8_t) ((Encoding >> (8 * i)) & 0xff));
329   }
330 
331   // NSA encoding.
332   if (AMDGPU::isGFX10Plus(STI) && Desc.TSFlags & SIInstrFlags::MIMG) {
333     int vaddr0 = AMDGPU::getNamedOperandIdx(MI.getOpcode(),
334                                             AMDGPU::OpName::vaddr0);
335     int srsrc = AMDGPU::getNamedOperandIdx(MI.getOpcode(),
336                                            AMDGPU::OpName::srsrc);
337     assert(vaddr0 >= 0 && srsrc > vaddr0);
338     unsigned NumExtraAddrs = srsrc - vaddr0 - 1;
339     unsigned NumPadding = (-NumExtraAddrs) & 3;
340 
341     for (unsigned i = 0; i < NumExtraAddrs; ++i)
342       OS.write((uint8_t)getMachineOpValue(MI, MI.getOperand(vaddr0 + 1 + i),
343                                           Fixups, STI));
344     for (unsigned i = 0; i < NumPadding; ++i)
345       OS.write(0);
346   }
347 
348   if ((bytes > 8 && STI.getFeatureBits()[AMDGPU::FeatureVOP3Literal]) ||
349       (bytes > 4 && !STI.getFeatureBits()[AMDGPU::FeatureVOP3Literal]))
350     return;
351 
352   // Do not print literals from SISrc Operands for insts with mandatory literals
353   int ImmLitIdx =
354       AMDGPU::getNamedOperandIdx(MI.getOpcode(), AMDGPU::OpName::imm);
355   if (ImmLitIdx != -1)
356     return;
357 
358   // Check for additional literals
359   for (unsigned i = 0, e = Desc.getNumOperands(); i < e; ++i) {
360 
361     // Check if this operand should be encoded as [SV]Src
362     if (!AMDGPU::isSISrcOperand(Desc, i))
363       continue;
364 
365     // Is this operand a literal immediate?
366     const MCOperand &Op = MI.getOperand(i);
367     if (getLitEncoding(Op, Desc.OpInfo[i], STI) != 255)
368       continue;
369 
370     // Yes! Encode it
371     int64_t Imm = 0;
372 
373     if (Op.isImm())
374       Imm = Op.getImm();
375     else if (Op.isExpr()) {
376       if (const auto *C = dyn_cast<MCConstantExpr>(Op.getExpr()))
377         Imm = C->getValue();
378 
379     } else if (!Op.isExpr()) // Exprs will be replaced with a fixup value.
380       llvm_unreachable("Must be immediate or expr");
381 
382     for (unsigned j = 0; j < 4; j++) {
383       OS.write((uint8_t) ((Imm >> (8 * j)) & 0xff));
384     }
385 
386     // Only one literal value allowed
387     break;
388   }
389 }
390 
391 unsigned SIMCCodeEmitter::getSOPPBrEncoding(const MCInst &MI, unsigned OpNo,
392                                             SmallVectorImpl<MCFixup> &Fixups,
393                                             const MCSubtargetInfo &STI) const {
394   const MCOperand &MO = MI.getOperand(OpNo);
395 
396   if (MO.isExpr()) {
397     const MCExpr *Expr = MO.getExpr();
398     MCFixupKind Kind = (MCFixupKind)AMDGPU::fixup_si_sopp_br;
399     Fixups.push_back(MCFixup::create(0, Expr, Kind, MI.getLoc()));
400     return 0;
401   }
402 
403   return getMachineOpValue(MI, MO, Fixups, STI);
404 }
405 
406 unsigned SIMCCodeEmitter::getSMEMOffsetEncoding(const MCInst &MI, unsigned OpNo,
407                                                 SmallVectorImpl<MCFixup> &Fixups,
408                                                 const MCSubtargetInfo &STI) const {
409   auto Offset = MI.getOperand(OpNo).getImm();
410   // VI only supports 20-bit unsigned offsets.
411   assert(!AMDGPU::isVI(STI) || isUInt<20>(Offset));
412   return Offset;
413 }
414 
415 unsigned
416 SIMCCodeEmitter::getSDWASrcEncoding(const MCInst &MI, unsigned OpNo,
417                                     SmallVectorImpl<MCFixup> &Fixups,
418                                     const MCSubtargetInfo &STI) const {
419   using namespace AMDGPU::SDWA;
420 
421   uint64_t RegEnc = 0;
422 
423   const MCOperand &MO = MI.getOperand(OpNo);
424 
425   if (MO.isReg()) {
426     unsigned Reg = MO.getReg();
427     RegEnc |= MRI.getEncodingValue(Reg);
428     RegEnc &= SDWA9EncValues::SRC_VGPR_MASK;
429     if (AMDGPU::isSGPR(AMDGPU::mc2PseudoReg(Reg), &MRI)) {
430       RegEnc |= SDWA9EncValues::SRC_SGPR_MASK;
431     }
432     return RegEnc;
433   } else {
434     const MCInstrDesc &Desc = MCII.get(MI.getOpcode());
435     uint32_t Enc = getLitEncoding(MO, Desc.OpInfo[OpNo], STI);
436     if (Enc != ~0U && Enc != 255) {
437       return Enc | SDWA9EncValues::SRC_SGPR_MASK;
438     }
439   }
440 
441   llvm_unreachable("Unsupported operand kind");
442   return 0;
443 }
444 
445 unsigned
446 SIMCCodeEmitter::getSDWAVopcDstEncoding(const MCInst &MI, unsigned OpNo,
447                                         SmallVectorImpl<MCFixup> &Fixups,
448                                         const MCSubtargetInfo &STI) const {
449   using namespace AMDGPU::SDWA;
450 
451   uint64_t RegEnc = 0;
452 
453   const MCOperand &MO = MI.getOperand(OpNo);
454 
455   unsigned Reg = MO.getReg();
456   if (Reg != AMDGPU::VCC && Reg != AMDGPU::VCC_LO) {
457     RegEnc |= MRI.getEncodingValue(Reg);
458     RegEnc &= SDWA9EncValues::VOPC_DST_SGPR_MASK;
459     RegEnc |= SDWA9EncValues::VOPC_DST_VCC_MASK;
460   }
461   return RegEnc;
462 }
463 
464 unsigned
465 SIMCCodeEmitter::getAVOperandEncoding(const MCInst &MI, unsigned OpNo,
466                                       SmallVectorImpl<MCFixup> &Fixups,
467                                       const MCSubtargetInfo &STI) const {
468   unsigned Reg = MI.getOperand(OpNo).getReg();
469   uint64_t Enc = MRI.getEncodingValue(Reg);
470 
471   // VGPR and AGPR have the same encoding, but SrcA and SrcB operands of mfma
472   // instructions use acc[0:1] modifier bits to distinguish. These bits are
473   // encoded as a virtual 9th bit of the register for these operands.
474   if (MRI.getRegClass(AMDGPU::AGPR_32RegClassID).contains(Reg) ||
475       MRI.getRegClass(AMDGPU::AReg_64RegClassID).contains(Reg) ||
476       MRI.getRegClass(AMDGPU::AReg_96RegClassID).contains(Reg) ||
477       MRI.getRegClass(AMDGPU::AReg_128RegClassID).contains(Reg) ||
478       MRI.getRegClass(AMDGPU::AReg_160RegClassID).contains(Reg) ||
479       MRI.getRegClass(AMDGPU::AReg_192RegClassID).contains(Reg) ||
480       MRI.getRegClass(AMDGPU::AReg_224RegClassID).contains(Reg) ||
481       MRI.getRegClass(AMDGPU::AReg_256RegClassID).contains(Reg) ||
482       MRI.getRegClass(AMDGPU::AGPR_LO16RegClassID).contains(Reg))
483     Enc |= 512;
484 
485   return Enc;
486 }
487 
488 static bool needsPCRel(const MCExpr *Expr) {
489   switch (Expr->getKind()) {
490   case MCExpr::SymbolRef: {
491     auto *SE = cast<MCSymbolRefExpr>(Expr);
492     MCSymbolRefExpr::VariantKind Kind = SE->getKind();
493     return Kind != MCSymbolRefExpr::VK_AMDGPU_ABS32_LO &&
494            Kind != MCSymbolRefExpr::VK_AMDGPU_ABS32_HI;
495   }
496   case MCExpr::Binary: {
497     auto *BE = cast<MCBinaryExpr>(Expr);
498     if (BE->getOpcode() == MCBinaryExpr::Sub)
499       return false;
500     return needsPCRel(BE->getLHS()) || needsPCRel(BE->getRHS());
501   }
502   case MCExpr::Unary:
503     return needsPCRel(cast<MCUnaryExpr>(Expr)->getSubExpr());
504   case MCExpr::Target:
505   case MCExpr::Constant:
506     return false;
507   }
508   llvm_unreachable("invalid kind");
509 }
510 
511 uint64_t SIMCCodeEmitter::getMachineOpValue(const MCInst &MI,
512                                             const MCOperand &MO,
513                                        SmallVectorImpl<MCFixup> &Fixups,
514                                        const MCSubtargetInfo &STI) const {
515   if (MO.isReg())
516     return MRI.getEncodingValue(MO.getReg());
517 
518   if (MO.isExpr() && MO.getExpr()->getKind() != MCExpr::Constant) {
519     // FIXME: If this is expression is PCRel or not should not depend on what
520     // the expression looks like. Given that this is just a general expression,
521     // it should probably be FK_Data_4 and whatever is producing
522     //
523     //    s_add_u32 s2, s2, (extern_const_addrspace+16
524     //
525     // And expecting a PCRel should instead produce
526     //
527     // .Ltmp1:
528     //   s_add_u32 s2, s2, (extern_const_addrspace+16)-.Ltmp1
529     MCFixupKind Kind;
530     if (needsPCRel(MO.getExpr()))
531       Kind = FK_PCRel_4;
532     else
533       Kind = FK_Data_4;
534 
535     const MCInstrDesc &Desc = MCII.get(MI.getOpcode());
536     uint32_t Offset = Desc.getSize();
537     assert(Offset == 4 || Offset == 8);
538 
539     Fixups.push_back(
540       MCFixup::create(Offset, MO.getExpr(), Kind, MI.getLoc()));
541   }
542 
543   // Figure out the operand number, needed for isSrcOperand check
544   unsigned OpNo = 0;
545   for (unsigned e = MI.getNumOperands(); OpNo < e; ++OpNo) {
546     if (&MO == &MI.getOperand(OpNo))
547       break;
548   }
549 
550   const MCInstrDesc &Desc = MCII.get(MI.getOpcode());
551   if (AMDGPU::isSISrcOperand(Desc, OpNo)) {
552     uint32_t Enc = getLitEncoding(MO, Desc.OpInfo[OpNo], STI);
553     if (Enc != ~0U)
554       return Enc;
555 
556   } else if (MO.isImm())
557     return MO.getImm();
558 
559   llvm_unreachable("Encoding of this operand type is not supported yet.");
560   return 0;
561 }
562 
563 #define ENABLE_INSTR_PREDICATE_VERIFIER
564 #include "AMDGPUGenMCCodeEmitter.inc"
565