1 //===-- X86/X86MCCodeEmitter.cpp - Convert X86 code to machine code -------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the X86MCCodeEmitter class.
12 //===----------------------------------------------------------------------===//
14 #define DEBUG_TYPE "x86-emitter"
16 #include "X86InstrInfo.h"
17 #include "llvm/MC/MCCodeEmitter.h"
18 #include "llvm/MC/MCInst.h"
19 #include "llvm/Support/raw_ostream.h"
23 class X86MCCodeEmitter : public MCCodeEmitter {
24 X86MCCodeEmitter(const X86MCCodeEmitter &); // DO NOT IMPLEMENT
25 void operator=(const X86MCCodeEmitter &); // DO NOT IMPLEMENT
26 const TargetMachine &TM;
27 const TargetInstrInfo &TII;
30 X86MCCodeEmitter(TargetMachine &tm, bool is64Bit)
31 : TM(tm), TII(*TM.getInstrInfo()) {
32 Is64BitMode = is64Bit;
35 ~X86MCCodeEmitter() {}
37 static unsigned GetX86RegNum(const MCOperand &MO) {
38 return X86RegisterInfo::getX86RegNum(MO.getReg());
41 void EmitByte(unsigned char C, raw_ostream &OS) const {
45 void EmitConstant(uint64_t Val, unsigned Size, raw_ostream &OS) const {
46 // Output the constant in little endian byte order.
47 for (unsigned i = 0; i != Size; ++i) {
48 EmitByte(Val & 255, OS);
53 void EmitDisplacementField(const MCOperand *RelocOp, int DispVal,
54 int64_t Adj, bool IsPCRel, raw_ostream &OS) const;
56 inline static unsigned char ModRMByte(unsigned Mod, unsigned RegOpcode,
58 assert(Mod < 4 && RegOpcode < 8 && RM < 8 && "ModRM Fields out of range!");
59 return RM | (RegOpcode << 3) | (Mod << 6);
62 void EmitRegModRMByte(const MCOperand &ModRMReg, unsigned RegOpcodeFld,
63 raw_ostream &OS) const {
64 EmitByte(ModRMByte(3, RegOpcodeFld, GetX86RegNum(ModRMReg)), OS);
67 void EmitSIBByte(unsigned SS, unsigned Index, unsigned Base,
68 raw_ostream &OS) const {
69 // SIB byte is in the same format as the ModRMByte...
70 EmitByte(ModRMByte(SS, Index, Base), OS);
74 void EmitMemModRMByte(const MCInst &MI, unsigned Op,
75 unsigned RegOpcodeField, intptr_t PCAdj,
76 raw_ostream &OS) const;
78 void EncodeInstruction(const MCInst &MI, raw_ostream &OS) const;
82 } // end anonymous namespace
85 MCCodeEmitter *llvm::createX86_32MCCodeEmitter(const Target &,
87 return new X86MCCodeEmitter(TM, false);
90 MCCodeEmitter *llvm::createX86_64MCCodeEmitter(const Target &,
92 return new X86MCCodeEmitter(TM, true);
96 /// isDisp8 - Return true if this signed displacement fits in a 8-bit
97 /// sign-extended field.
98 static bool isDisp8(int Value) {
99 return Value == (signed char)Value;
102 void X86MCCodeEmitter::
103 EmitDisplacementField(const MCOperand *RelocOp, int DispVal,
104 int64_t Adj, bool IsPCRel, raw_ostream &OS) const {
105 // If this is a simple integer displacement that doesn't require a relocation,
108 EmitConstant(DispVal, 4, OS);
112 assert(0 && "Reloc not handled yet");
114 // Otherwise, this is something that requires a relocation. Emit it as such
116 unsigned RelocType = Is64BitMode ?
117 (IsPCRel ? X86::reloc_pcrel_word : X86::reloc_absolute_word_sext)
118 : (IsPIC ? X86::reloc_picrel_word : X86::reloc_absolute_word);
119 if (RelocOp->isGlobal()) {
120 // In 64-bit static small code model, we could potentially emit absolute.
121 // But it's probably not beneficial. If the MCE supports using RIP directly
122 // do it, otherwise fallback to absolute (this is determined by IsPCRel).
123 // 89 05 00 00 00 00 mov %eax,0(%rip) # PC-relative
124 // 89 04 25 00 00 00 00 mov %eax,0x0 # Absolute
125 bool Indirect = gvNeedsNonLazyPtr(*RelocOp, TM);
126 emitGlobalAddress(RelocOp->getGlobal(), RelocType, RelocOp->getOffset(),
128 } else if (RelocOp->isSymbol()) {
129 emitExternalSymbolAddress(RelocOp->getSymbolName(), RelocType);
130 } else if (RelocOp->isCPI()) {
131 emitConstPoolAddress(RelocOp->getIndex(), RelocType,
132 RelocOp->getOffset(), Adj);
134 assert(RelocOp->isJTI() && "Unexpected machine operand!");
135 emitJumpTableAddress(RelocOp->getIndex(), RelocType, Adj);
141 void X86MCCodeEmitter::EmitMemModRMByte(const MCInst &MI, unsigned Op,
142 unsigned RegOpcodeField,
144 raw_ostream &OS) const {
145 const MCOperand &Op3 = MI.getOperand(Op+3);
147 const MCOperand *DispForReloc = 0;
149 // Figure out what sort of displacement we have to handle here.
151 DispVal = Op3.getImm();
153 assert(0 && "relocatable operand");
155 if (Op3.isGlobal()) {
157 } else if (Op3.isSymbol()) {
159 } else if (Op3.isCPI()) {
160 if (!MCE.earlyResolveAddresses() || Is64BitMode || IsPIC) {
163 DispVal += MCE.getConstantPoolEntryAddress(Op3.getIndex());
164 DispVal += Op3.getOffset();
168 if (!MCE.earlyResolveAddresses() || Is64BitMode || IsPIC) {
171 DispVal += MCE.getJumpTableEntryAddress(Op3.getIndex());
176 const MCOperand &Base = MI.getOperand(Op);
177 const MCOperand &Scale = MI.getOperand(Op+1);
178 const MCOperand &IndexReg = MI.getOperand(Op+2);
179 unsigned BaseReg = Base.getReg();
182 bool IsPCRel = false;
184 // Determine whether a SIB byte is needed.
185 // If no BaseReg, issue a RIP relative instruction only if the MCE can
186 // resolve addresses on-the-fly, otherwise use SIB (Intel Manual 2A, table
187 // 2-7) and absolute references.
188 if (// The SIB byte must be used if there is an index register.
189 IndexReg.getReg() == 0 &&
190 // The SIB byte must be used if the base is ESP/RSP.
191 BaseReg != X86::ESP && BaseReg != X86::RSP &&
192 // If there is no base register and we're in 64-bit mode, we need a SIB
193 // byte to emit an addr that is just 'disp32' (the non-RIP relative form).
194 (!Is64BitMode || BaseReg != 0)) {
196 if (BaseReg == 0 || // [disp32] in X86-32 mode
197 BaseReg == X86::RIP) { // [disp32+RIP] in X86-64 mode
198 EmitByte(ModRMByte(0, RegOpcodeField, 5), OS);
199 EmitDisplacementField(DispForReloc, DispVal, PCAdj, true, OS);
203 unsigned BaseRegNo = GetX86RegNum(Base);
205 // If the base is not EBP/ESP and there is no displacement, use simple
206 // indirect register encoding, this handles addresses like [EAX]. The
207 // encoding for [EBP] with no displacement means [disp32] so we handle it
208 // by emitting a displacement of 0 below.
209 if (!DispForReloc && DispVal == 0 && BaseRegNo != N86::EBP) {
210 EmitByte(ModRMByte(0, RegOpcodeField, BaseRegNo), OS);
214 // Otherwise, if the displacement fits in a byte, encode as [REG+disp8].
215 if (!DispForReloc && isDisp8(DispVal)) {
216 EmitByte(ModRMByte(1, RegOpcodeField, BaseRegNo), OS);
217 EmitConstant(DispVal, 1, OS);
221 // Otherwise, emit the most general non-SIB encoding: [REG+disp32]
222 EmitByte(ModRMByte(2, RegOpcodeField, BaseRegNo), OS);
223 EmitDisplacementField(DispForReloc, DispVal, PCAdj, IsPCRel, OS);
227 // We need a SIB byte, so start by outputting the ModR/M byte first
228 assert(IndexReg.getReg() != X86::ESP &&
229 IndexReg.getReg() != X86::RSP && "Cannot use ESP as index reg!");
231 bool ForceDisp32 = false;
232 bool ForceDisp8 = false;
234 // If there is no base register, we emit the special case SIB byte with
235 // MOD=0, BASE=5, to JUST get the index, scale, and displacement.
236 EmitByte(ModRMByte(0, RegOpcodeField, 4), OS);
238 } else if (DispForReloc) {
239 // Emit the normal disp32 encoding.
240 EmitByte(ModRMByte(2, RegOpcodeField, 4), OS);
242 } else if (DispVal == 0 && BaseReg != X86::EBP) {
243 // Emit no displacement ModR/M byte
244 EmitByte(ModRMByte(0, RegOpcodeField, 4), OS);
245 } else if (isDisp8(DispVal)) {
246 // Emit the disp8 encoding.
247 EmitByte(ModRMByte(1, RegOpcodeField, 4), OS);
248 ForceDisp8 = true; // Make sure to force 8 bit disp if Base=EBP
250 // Emit the normal disp32 encoding.
251 EmitByte(ModRMByte(2, RegOpcodeField, 4), OS);
254 // Calculate what the SS field value should be...
255 static const unsigned SSTable[] = { ~0, 0, 1, ~0, 2, ~0, ~0, ~0, 3 };
256 unsigned SS = SSTable[Scale.getImm()];
259 // Handle the SIB byte for the case where there is no base, see Intel
260 // Manual 2A, table 2-7. The displacement has already been output.
262 if (IndexReg.getReg())
263 IndexRegNo = GetX86RegNum(IndexReg);
264 else // Examples: [ESP+1*<noreg>+4] or [scaled idx]+disp32 (MOD=0,BASE=5)
266 EmitSIBByte(SS, IndexRegNo, 5, OS);
269 if (IndexReg.getReg())
270 IndexRegNo = GetX86RegNum(IndexReg);
272 IndexRegNo = 4; // For example [ESP+1*<noreg>+4]
273 EmitSIBByte(SS, IndexRegNo, GetX86RegNum(Base), OS);
276 // Do we need to output a displacement?
278 EmitConstant(DispVal, 1, OS);
279 else if (DispVal != 0 || ForceDisp32)
280 EmitDisplacementField(DispForReloc, DispVal, PCAdj, IsPCRel, OS);
283 /// DetermineREXPrefix - Determine if the MCInst has to be encoded with a X86-64
284 /// REX prefix which specifies 1) 64-bit instructions, 2) non-default operand
285 /// size, and 3) use of X86-64 extended registers.
286 static unsigned DetermineREXPrefix(const MCInst &MI, unsigned TSFlags,
287 const TargetInstrDesc &Desc) {
290 // Pseudo instructions do not need REX prefix byte.
291 if ((TSFlags & X86II::FormMask) == X86II::Pseudo)
293 if (TSFlags & X86II::REX_W)
296 if (MI.getNumOperands() == 0) return REX;
298 unsigned NumOps = MI.getNumOperands();
299 // FIXME: MCInst should explicitize the two-addrness.
300 bool isTwoAddr = NumOps > 1 &&
301 Desc.getOperandConstraint(1, TOI::TIED_TO) != -1;
303 // If it accesses SPL, BPL, SIL, or DIL, then it requires a 0x40 REX prefix.
304 unsigned i = isTwoAddr ? 1 : 0;
305 for (; i != NumOps; ++i) {
306 const MCOperand &MO = MI.getOperand(i);
307 if (!MO.isReg()) continue;
308 unsigned Reg = MO.getReg();
309 if (!X86InstrInfo::isX86_64NonExtLowByteReg(Reg)) continue;
310 // FIXME: The caller of DetermineREXPrefix slaps this prefix onto anything
311 // that returns non-zero.
316 switch (TSFlags & X86II::FormMask) {
317 case X86II::MRMInitReg: assert(0 && "FIXME: Remove this!");
318 case X86II::MRMSrcReg:
319 if (MI.getOperand(0).isReg() &&
320 X86InstrInfo::isX86_64ExtendedReg(MI.getOperand(0).getReg()))
322 i = isTwoAddr ? 2 : 1;
323 for (; i != NumOps; ++i) {
324 const MCOperand &MO = MI.getOperand(i);
325 if (MO.isReg() && X86InstrInfo::isX86_64ExtendedReg(MO.getReg()))
329 case X86II::MRMSrcMem: {
330 if (MI.getOperand(0).isReg() &&
331 X86InstrInfo::isX86_64ExtendedReg(MI.getOperand(0).getReg()))
334 i = isTwoAddr ? 2 : 1;
335 for (; i != NumOps; ++i) {
336 const MCOperand &MO = MI.getOperand(i);
338 if (X86InstrInfo::isX86_64ExtendedReg(MO.getReg()))
345 case X86II::MRM0m: case X86II::MRM1m:
346 case X86II::MRM2m: case X86II::MRM3m:
347 case X86II::MRM4m: case X86II::MRM5m:
348 case X86II::MRM6m: case X86II::MRM7m:
349 case X86II::MRMDestMem: {
350 unsigned e = (isTwoAddr ? X86AddrNumOperands+1 : X86AddrNumOperands);
351 i = isTwoAddr ? 1 : 0;
352 if (NumOps > e && MI.getOperand(e).isReg() &&
353 X86InstrInfo::isX86_64ExtendedReg(MI.getOperand(e).getReg()))
356 for (; i != e; ++i) {
357 const MCOperand &MO = MI.getOperand(i);
359 if (X86InstrInfo::isX86_64ExtendedReg(MO.getReg()))
367 if (MI.getOperand(0).isReg() &&
368 X86InstrInfo::isX86_64ExtendedReg(MI.getOperand(0).getReg()))
370 i = isTwoAddr ? 2 : 1;
371 for (unsigned e = NumOps; i != e; ++i) {
372 const MCOperand &MO = MI.getOperand(i);
373 if (MO.isReg() && X86InstrInfo::isX86_64ExtendedReg(MO.getReg()))
381 void X86MCCodeEmitter::
382 EncodeInstruction(const MCInst &MI, raw_ostream &OS) const {
383 unsigned Opcode = MI.getOpcode();
384 const TargetInstrDesc &Desc = TII.get(Opcode);
385 unsigned TSFlags = Desc.TSFlags;
387 // FIXME: We should emit the prefixes in exactly the same order as GAS does,
388 // in order to provide diffability.
390 // Emit the lock opcode prefix as needed.
391 if (TSFlags & X86II::LOCK)
394 // Emit segment override opcode prefix as needed.
395 switch (TSFlags & X86II::SegOvrMask) {
396 default: assert(0 && "Invalid segment!");
397 case 0: break; // No segment override!
406 // Emit the repeat opcode prefix as needed.
407 if ((TSFlags & X86II::Op0Mask) == X86II::REP)
410 // Emit the operand size opcode prefix as needed.
411 if (TSFlags & X86II::OpSize)
414 // Emit the address size opcode prefix as needed.
415 if (TSFlags & X86II::AdSize)
418 bool Need0FPrefix = false;
419 switch (TSFlags & X86II::Op0Mask) {
420 default: assert(0 && "Invalid prefix!");
421 case 0: break; // No prefix!
422 case X86II::REP: break; // already handled.
423 case X86II::TB: // Two-byte opcode prefix
424 case X86II::T8: // 0F 38
425 case X86II::TA: // 0F 3A
428 case X86II::TF: // F2 0F 38
432 case X86II::XS: // F3 0F
436 case X86II::XD: // F2 0F
440 case X86II::D8: EmitByte(0xD8, OS); break;
441 case X86II::D9: EmitByte(0xD9, OS); break;
442 case X86II::DA: EmitByte(0xDA, OS); break;
443 case X86II::DB: EmitByte(0xDB, OS); break;
444 case X86II::DC: EmitByte(0xDC, OS); break;
445 case X86II::DD: EmitByte(0xDD, OS); break;
446 case X86II::DE: EmitByte(0xDE, OS); break;
447 case X86II::DF: EmitByte(0xDF, OS); break;
450 // Handle REX prefix.
451 // FIXME: Can this come before F2 etc to simplify emission?
453 if (unsigned REX = DetermineREXPrefix(MI, TSFlags, Desc))
454 EmitByte(0x40 | REX, OS);
457 // 0x0F escape code must be emitted just before the opcode.
461 // FIXME: Pull this up into previous switch if REX can be moved earlier.
462 switch (TSFlags & X86II::Op0Mask) {
463 case X86II::TF: // F2 0F 38
464 case X86II::T8: // 0F 38
467 case X86II::TA: // 0F 3A
472 // If this is a two-address instruction, skip one of the register operands.
473 unsigned NumOps = Desc.getNumOperands();
475 if (NumOps > 1 && Desc.getOperandConstraint(1, TOI::TIED_TO) != -1)
477 else if (NumOps > 2 && Desc.getOperandConstraint(NumOps-1, TOI::TIED_TO)== 0)
478 // Skip the last source operand that is tied_to the dest reg. e.g. LXADD32
481 unsigned char BaseOpcode = X86II::getBaseOpcodeFor(TSFlags);
482 switch (TSFlags & X86II::FormMask) {
483 case X86II::MRMInitReg:
484 assert(0 && "FIXME: Remove this form when the JIT moves to MCCodeEmitter!");
485 default: errs() << "FORM: " << (TSFlags & X86II::FormMask) << "\n";
486 assert(0 && "Unknown FormMask value in X86MCCodeEmitter!");
487 case X86II::RawFrm: {
488 EmitByte(BaseOpcode, OS);
493 assert(0 && "Unimpl RawFrm expr");
497 case X86II::AddRegFrm: {
498 EmitByte(BaseOpcode + GetX86RegNum(MI.getOperand(CurOp++)),OS);
502 const MCOperand &MO1 = MI.getOperand(CurOp++);
504 unsigned Size = X86II::getSizeOfImm(TSFlags);
505 EmitConstant(MO1.getImm(), Size, OS);
509 assert(0 && "Unimpl AddRegFrm expr");
513 case X86II::MRMDestReg:
514 EmitByte(BaseOpcode, OS);
515 EmitRegModRMByte(MI.getOperand(CurOp),
516 GetX86RegNum(MI.getOperand(CurOp+1)), OS);
519 EmitConstant(MI.getOperand(CurOp++).getImm(),
520 X86II::getSizeOfImm(TSFlags), OS);
523 case X86II::MRMDestMem:
524 EmitByte(BaseOpcode, OS);
525 EmitMemModRMByte(MI, CurOp,
526 GetX86RegNum(MI.getOperand(CurOp + X86AddrNumOperands)),
528 CurOp += X86AddrNumOperands + 1;
530 EmitConstant(MI.getOperand(CurOp++).getImm(),
531 X86II::getSizeOfImm(TSFlags), OS);
534 case X86II::MRMSrcReg:
535 EmitByte(BaseOpcode, OS);
536 EmitRegModRMByte(MI.getOperand(CurOp+1), GetX86RegNum(MI.getOperand(CurOp)),
540 EmitConstant(MI.getOperand(CurOp++).getImm(),
541 X86II::getSizeOfImm(TSFlags), OS);
544 case X86II::MRMSrcMem: {
545 EmitByte(BaseOpcode, OS);
547 // FIXME: Maybe lea should have its own form? This is a horrible hack.
549 if (Opcode == X86::LEA64r || Opcode == X86::LEA64_32r ||
550 Opcode == X86::LEA16r || Opcode == X86::LEA32r)
551 AddrOperands = X86AddrNumOperands - 1; // No segment register
553 AddrOperands = X86AddrNumOperands;
555 // FIXME: What is this actually doing?
556 intptr_t PCAdj = (CurOp + AddrOperands + 1 != NumOps) ?
557 X86II::getSizeOfImm(TSFlags) : 0;
559 EmitMemModRMByte(MI, CurOp+1, GetX86RegNum(MI.getOperand(CurOp)),
561 CurOp += AddrOperands + 1;
563 EmitConstant(MI.getOperand(CurOp++).getImm(),
564 X86II::getSizeOfImm(TSFlags), OS);
568 case X86II::MRM0r: case X86II::MRM1r:
569 case X86II::MRM2r: case X86II::MRM3r:
570 case X86II::MRM4r: case X86II::MRM5r:
571 case X86II::MRM6r: case X86II::MRM7r: {
572 EmitByte(BaseOpcode, OS);
574 // Special handling of lfence, mfence, monitor, and mwait.
575 // FIXME: This is terrible, they should get proper encoding bits in TSFlags.
576 if (Opcode == X86::LFENCE || Opcode == X86::MFENCE ||
577 Opcode == X86::MONITOR || Opcode == X86::MWAIT) {
578 EmitByte(ModRMByte(3, (TSFlags & X86II::FormMask)-X86II::MRM0r, 0), OS);
582 case X86::MONITOR: EmitByte(0xC8, OS); break;
583 case X86::MWAIT: EmitByte(0xC9, OS); break;
586 EmitRegModRMByte(MI.getOperand(CurOp++),
587 (TSFlags & X86II::FormMask)-X86II::MRM0r,
594 const MCOperand &MO1 = MI.getOperand(CurOp++);
596 EmitConstant(MO1.getImm(), X86II::getSizeOfImm(TSFlags), OS);
600 assert(0 && "relo unimpl");
602 unsigned rt = Is64BitMode ? X86::reloc_pcrel_word
603 : (IsPIC ? X86::reloc_picrel_word : X86::reloc_absolute_word);
604 if (Opcode == X86::MOV64ri32)
605 rt = X86::reloc_absolute_word_sext; // FIXME: add X86II flag?
606 if (MO1.isGlobal()) {
607 bool Indirect = gvNeedsNonLazyPtr(MO1, TM);
608 emitGlobalAddress(MO1.getGlobal(), rt, MO1.getOffset(), 0,
610 } else if (MO1.isSymbol())
611 emitExternalSymbolAddress(MO1.getSymbolName(), rt);
612 else if (MO1.isCPI())
613 emitConstPoolAddress(MO1.getIndex(), rt);
614 else if (MO1.isJTI())
615 emitJumpTableAddress(MO1.getIndex(), rt);
619 case X86II::MRM0m: case X86II::MRM1m:
620 case X86II::MRM2m: case X86II::MRM3m:
621 case X86II::MRM4m: case X86II::MRM5m:
622 case X86II::MRM6m: case X86II::MRM7m: {
624 if (CurOp + X86AddrNumOperands != NumOps) {
625 if (MI.getOperand(CurOp+X86AddrNumOperands).isImm())
626 PCAdj = X86II::getSizeOfImm(TSFlags);
631 EmitByte(BaseOpcode, OS);
632 EmitMemModRMByte(MI, CurOp, (TSFlags & X86II::FormMask)-X86II::MRM0m,
634 CurOp += X86AddrNumOperands;
639 const MCOperand &MO = MI.getOperand(CurOp++);
641 EmitConstant(MO.getImm(), X86II::getSizeOfImm(TSFlags), OS);
645 assert(0 && "relo not handled");
647 unsigned rt = Is64BitMode ? X86::reloc_pcrel_word
648 : (IsPIC ? X86::reloc_picrel_word : X86::reloc_absolute_word);
649 if (Opcode == X86::MOV64mi32)
650 rt = X86::reloc_absolute_word_sext; // FIXME: add X86II flag?
652 bool Indirect = gvNeedsNonLazyPtr(MO, TM);
653 emitGlobalAddress(MO.getGlobal(), rt, MO.getOffset(), 0,
655 } else if (MO.isSymbol())
656 emitExternalSymbolAddress(MO.getSymbolName(), rt);
658 emitConstPoolAddress(MO.getIndex(), rt);
660 emitJumpTableAddress(MO.getIndex(), rt);
668 if (/*!Desc.isVariadic() &&*/ CurOp != NumOps) {
669 errs() << "Cannot encode all operands of: ";