LLVM 17.0.0git
MCAssembler.cpp
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1//===- lib/MC/MCAssembler.cpp - Assembler Backend Implementation ----------===//
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
10#include "llvm/ADT/ArrayRef.h"
13#include "llvm/ADT/Statistic.h"
14#include "llvm/ADT/StringRef.h"
15#include "llvm/ADT/Twine.h"
17#include "llvm/MC/MCAsmInfo.h"
18#include "llvm/MC/MCAsmLayout.h"
20#include "llvm/MC/MCCodeView.h"
21#include "llvm/MC/MCContext.h"
22#include "llvm/MC/MCDwarf.h"
23#include "llvm/MC/MCExpr.h"
24#include "llvm/MC/MCFixup.h"
26#include "llvm/MC/MCFragment.h"
27#include "llvm/MC/MCInst.h"
29#include "llvm/MC/MCSection.h"
30#include "llvm/MC/MCSymbol.h"
31#include "llvm/MC/MCValue.h"
34#include "llvm/Support/Debug.h"
37#include "llvm/Support/LEB128.h"
39#include <cassert>
40#include <cstdint>
41#include <tuple>
42#include <utility>
43
44using namespace llvm;
45
46namespace llvm {
47class MCSubtargetInfo;
48}
49
50#define DEBUG_TYPE "assembler"
51
52namespace {
53namespace stats {
54
55STATISTIC(EmittedFragments, "Number of emitted assembler fragments - total");
56STATISTIC(EmittedRelaxableFragments,
57 "Number of emitted assembler fragments - relaxable");
58STATISTIC(EmittedDataFragments,
59 "Number of emitted assembler fragments - data");
60STATISTIC(EmittedCompactEncodedInstFragments,
61 "Number of emitted assembler fragments - compact encoded inst");
62STATISTIC(EmittedAlignFragments,
63 "Number of emitted assembler fragments - align");
64STATISTIC(EmittedFillFragments,
65 "Number of emitted assembler fragments - fill");
66STATISTIC(EmittedNopsFragments, "Number of emitted assembler fragments - nops");
67STATISTIC(EmittedOrgFragments, "Number of emitted assembler fragments - org");
68STATISTIC(evaluateFixup, "Number of evaluated fixups");
69STATISTIC(FragmentLayouts, "Number of fragment layouts");
70STATISTIC(ObjectBytes, "Number of emitted object file bytes");
71STATISTIC(RelaxationSteps, "Number of assembler layout and relaxation steps");
72STATISTIC(RelaxedInstructions, "Number of relaxed instructions");
73
74} // end namespace stats
75} // end anonymous namespace
76
77// FIXME FIXME FIXME: There are number of places in this file where we convert
78// what is a 64-bit assembler value used for computation into a value in the
79// object file, which may truncate it. We should detect that truncation where
80// invalid and report errors back.
81
82/* *** */
83
85 std::unique_ptr<MCAsmBackend> Backend,
86 std::unique_ptr<MCCodeEmitter> Emitter,
87 std::unique_ptr<MCObjectWriter> Writer)
88 : Context(Context), Backend(std::move(Backend)),
89 Emitter(std::move(Emitter)), Writer(std::move(Writer)),
90 BundleAlignSize(0), RelaxAll(false), SubsectionsViaSymbols(false),
91 IncrementalLinkerCompatible(false), ELFHeaderEFlags(0) {
92 VersionInfo.Major = 0; // Major version == 0 for "none specified"
93 DarwinTargetVariantVersionInfo.Major = 0;
94}
95
97
99 Sections.clear();
100 Symbols.clear();
101 IndirectSymbols.clear();
102 DataRegions.clear();
103 LinkerOptions.clear();
104 FileNames.clear();
105 ThumbFuncs.clear();
106 BundleAlignSize = 0;
107 RelaxAll = false;
108 SubsectionsViaSymbols = false;
109 IncrementalLinkerCompatible = false;
110 ELFHeaderEFlags = 0;
111 LOHContainer.reset();
112 VersionInfo.Major = 0;
113 VersionInfo.SDKVersion = VersionTuple();
114 DarwinTargetVariantVersionInfo.Major = 0;
115 DarwinTargetVariantVersionInfo.SDKVersion = VersionTuple();
116
117 // reset objects owned by us
118 if (getBackendPtr())
119 getBackendPtr()->reset();
120 if (getEmitterPtr())
121 getEmitterPtr()->reset();
122 if (getWriterPtr())
123 getWriterPtr()->reset();
125}
126
128 if (Section.isRegistered())
129 return false;
130 Sections.push_back(&Section);
131 Section.setIsRegistered(true);
132 return true;
133}
134
135bool MCAssembler::isThumbFunc(const MCSymbol *Symbol) const {
136 if (ThumbFuncs.count(Symbol))
137 return true;
138
139 if (!Symbol->isVariable())
140 return false;
141
142 const MCExpr *Expr = Symbol->getVariableValue();
143
144 MCValue V;
145 if (!Expr->evaluateAsRelocatable(V, nullptr, nullptr))
146 return false;
147
149 return false;
150
151 const MCSymbolRefExpr *Ref = V.getSymA();
152 if (!Ref)
153 return false;
154
155 if (Ref->getKind() != MCSymbolRefExpr::VK_None)
156 return false;
157
158 const MCSymbol &Sym = Ref->getSymbol();
159 if (!isThumbFunc(&Sym))
160 return false;
161
162 ThumbFuncs.insert(Symbol); // Cache it.
163 return true;
164}
165
167 // Non-temporary labels should always be visible to the linker.
168 if (!Symbol.isTemporary())
169 return true;
170
171 if (Symbol.isUsedInReloc())
172 return true;
173
174 return false;
175}
176
177const MCSymbol *MCAssembler::getAtom(const MCSymbol &S) const {
178 // Linker visible symbols define atoms.
180 return &S;
181
182 // Absolute and undefined symbols have no defining atom.
183 if (!S.isInSection())
184 return nullptr;
185
186 // Non-linker visible symbols in sections which can't be atomized have no
187 // defining atom.
188 if (!getContext().getAsmInfo()->isSectionAtomizableBySymbols(
189 *S.getFragment()->getParent()))
190 return nullptr;
191
192 // Otherwise, return the atom for the containing fragment.
193 return S.getFragment()->getAtom();
194}
195
196bool MCAssembler::evaluateFixup(const MCAsmLayout &Layout,
197 const MCFixup &Fixup, const MCFragment *DF,
199 bool &WasForced) const {
200 ++stats::evaluateFixup;
201
202 // FIXME: This code has some duplication with recordRelocation. We should
203 // probably merge the two into a single callback that tries to evaluate a
204 // fixup and records a relocation if one is needed.
205
206 // On error claim to have completely evaluated the fixup, to prevent any
207 // further processing from being done.
208 const MCExpr *Expr = Fixup.getValue();
209 MCContext &Ctx = getContext();
210 Value = 0;
211 WasForced = false;
212 if (!Expr->evaluateAsRelocatable(Target, &Layout, &Fixup)) {
213 Ctx.reportError(Fixup.getLoc(), "expected relocatable expression");
214 return true;
215 }
216 if (const MCSymbolRefExpr *RefB = Target.getSymB()) {
217 if (RefB->getKind() != MCSymbolRefExpr::VK_None) {
218 Ctx.reportError(Fixup.getLoc(),
219 "unsupported subtraction of qualified symbol");
220 return true;
221 }
222 }
223
224 assert(getBackendPtr() && "Expected assembler backend");
225 bool IsTarget = getBackendPtr()->getFixupKindInfo(Fixup.getKind()).Flags &
227
228 if (IsTarget)
229 return getBackend().evaluateTargetFixup(*this, Layout, Fixup, DF, Target,
230 Value, WasForced);
231
232 unsigned FixupFlags = getBackendPtr()->getFixupKindInfo(Fixup.getKind()).Flags;
233 bool IsPCRel = getBackendPtr()->getFixupKindInfo(Fixup.getKind()).Flags &
235
236 bool IsResolved = false;
237 if (IsPCRel) {
238 if (Target.getSymB()) {
239 IsResolved = false;
240 } else if (!Target.getSymA()) {
241 IsResolved = false;
242 } else {
243 const MCSymbolRefExpr *A = Target.getSymA();
244 const MCSymbol &SA = A->getSymbol();
245 if (A->getKind() != MCSymbolRefExpr::VK_None || SA.isUndefined()) {
246 IsResolved = false;
247 } else if (auto *Writer = getWriterPtr()) {
248 IsResolved = (FixupFlags & MCFixupKindInfo::FKF_Constant) ||
249 Writer->isSymbolRefDifferenceFullyResolvedImpl(
250 *this, SA, *DF, false, true);
251 }
252 }
253 } else {
254 IsResolved = Target.isAbsolute();
255 }
256
257 Value = Target.getConstant();
258
259 if (const MCSymbolRefExpr *A = Target.getSymA()) {
260 const MCSymbol &Sym = A->getSymbol();
261 if (Sym.isDefined())
262 Value += Layout.getSymbolOffset(Sym);
263 }
264 if (const MCSymbolRefExpr *B = Target.getSymB()) {
265 const MCSymbol &Sym = B->getSymbol();
266 if (Sym.isDefined())
267 Value -= Layout.getSymbolOffset(Sym);
268 }
269
270 bool ShouldAlignPC = getBackend().getFixupKindInfo(Fixup.getKind()).Flags &
272 assert((ShouldAlignPC ? IsPCRel : true) &&
273 "FKF_IsAlignedDownTo32Bits is only allowed on PC-relative fixups!");
274
275 if (IsPCRel) {
276 uint32_t Offset = Layout.getFragmentOffset(DF) + Fixup.getOffset();
277
278 // A number of ARM fixups in Thumb mode require that the effective PC
279 // address be determined as the 32-bit aligned version of the actual offset.
280 if (ShouldAlignPC) Offset &= ~0x3;
281 Value -= Offset;
282 }
283
284 // Let the backend force a relocation if needed.
285 if (IsResolved && getBackend().shouldForceRelocation(*this, Fixup, Target)) {
286 IsResolved = false;
287 WasForced = true;
288 }
289
290 return IsResolved;
291}
292
294 const MCFragment &F) const {
295 assert(getBackendPtr() && "Requires assembler backend");
296 switch (F.getKind()) {
298 return cast<MCDataFragment>(F).getContents().size();
300 return cast<MCRelaxableFragment>(F).getContents().size();
302 return cast<MCCompactEncodedInstFragment>(F).getContents().size();
303 case MCFragment::FT_Fill: {
304 auto &FF = cast<MCFillFragment>(F);
305 int64_t NumValues = 0;
306 if (!FF.getNumValues().evaluateAsAbsolute(NumValues, Layout)) {
307 getContext().reportError(FF.getLoc(),
308 "expected assembly-time absolute expression");
309 return 0;
310 }
311 int64_t Size = NumValues * FF.getValueSize();
312 if (Size < 0) {
313 getContext().reportError(FF.getLoc(), "invalid number of bytes");
314 return 0;
315 }
316 return Size;
317 }
318
320 return cast<MCNopsFragment>(F).getNumBytes();
321
323 return cast<MCLEBFragment>(F).getContents().size();
324
326 return cast<MCBoundaryAlignFragment>(F).getSize();
327
329 return 4;
330
332 const MCAlignFragment &AF = cast<MCAlignFragment>(F);
333 unsigned Offset = Layout.getFragmentOffset(&AF);
334 unsigned Size = offsetToAlignment(Offset, AF.getAlignment());
335
336 // Insert extra Nops for code alignment if the target define
337 // shouldInsertExtraNopBytesForCodeAlign target hook.
338 if (AF.getParent()->useCodeAlign() && AF.hasEmitNops() &&
339 getBackend().shouldInsertExtraNopBytesForCodeAlign(AF, Size))
340 return Size;
341
342 // If we are padding with nops, force the padding to be larger than the
343 // minimum nop size.
344 if (Size > 0 && AF.hasEmitNops()) {
345 while (Size % getBackend().getMinimumNopSize())
346 Size += AF.getAlignment().value();
347 }
348 if (Size > AF.getMaxBytesToEmit())
349 return 0;
350 return Size;
351 }
352
353 case MCFragment::FT_Org: {
354 const MCOrgFragment &OF = cast<MCOrgFragment>(F);
356 if (!OF.getOffset().evaluateAsValue(Value, Layout)) {
358 "expected assembly-time absolute expression");
359 return 0;
360 }
361
362 uint64_t FragmentOffset = Layout.getFragmentOffset(&OF);
363 int64_t TargetLocation = Value.getConstant();
364 if (const MCSymbolRefExpr *A = Value.getSymA()) {
365 uint64_t Val;
366 if (!Layout.getSymbolOffset(A->getSymbol(), Val)) {
367 getContext().reportError(OF.getLoc(), "expected absolute expression");
368 return 0;
369 }
370 TargetLocation += Val;
371 }
372 int64_t Size = TargetLocation - FragmentOffset;
373 if (Size < 0 || Size >= 0x40000000) {
375 OF.getLoc(), "invalid .org offset '" + Twine(TargetLocation) +
376 "' (at offset '" + Twine(FragmentOffset) + "')");
377 return 0;
378 }
379 return Size;
380 }
381
383 return cast<MCDwarfLineAddrFragment>(F).getContents().size();
385 return cast<MCDwarfCallFrameFragment>(F).getContents().size();
387 return cast<MCCVInlineLineTableFragment>(F).getContents().size();
389 return cast<MCCVDefRangeFragment>(F).getContents().size();
391 return cast<MCPseudoProbeAddrFragment>(F).getContents().size();
393 llvm_unreachable("Should not have been added");
394 }
395
396 llvm_unreachable("invalid fragment kind");
397}
398
400 MCFragment *Prev = F->getPrevNode();
401
402 // We should never try to recompute something which is valid.
403 assert(!isFragmentValid(F) && "Attempt to recompute a valid fragment!");
404 // We should never try to compute the fragment layout if its predecessor
405 // isn't valid.
406 assert((!Prev || isFragmentValid(Prev)) &&
407 "Attempt to compute fragment before its predecessor!");
408
409 assert(!F->IsBeingLaidOut && "Already being laid out!");
410 F->IsBeingLaidOut = true;
411
412 ++stats::FragmentLayouts;
413
414 // Compute fragment offset and size.
415 if (Prev)
416 F->Offset = Prev->Offset + getAssembler().computeFragmentSize(*this, *Prev);
417 else
418 F->Offset = 0;
419 F->IsBeingLaidOut = false;
420 LastValidFragment[F->getParent()] = F;
421
422 // If bundling is enabled and this fragment has instructions in it, it has to
423 // obey the bundling restrictions. With padding, we'll have:
424 //
425 //
426 // BundlePadding
427 // |||
428 // -------------------------------------
429 // Prev |##########| F |
430 // -------------------------------------
431 // ^
432 // |
433 // F->Offset
434 //
435 // The fragment's offset will point to after the padding, and its computed
436 // size won't include the padding.
437 //
438 // When the -mc-relax-all flag is used, we optimize bundling by writting the
439 // padding directly into fragments when the instructions are emitted inside
440 // the streamer. When the fragment is larger than the bundle size, we need to
441 // ensure that it's bundle aligned. This means that if we end up with
442 // multiple fragments, we must emit bundle padding between fragments.
443 //
444 // ".align N" is an example of a directive that introduces multiple
445 // fragments. We could add a special case to handle ".align N" by emitting
446 // within-fragment padding (which would produce less padding when N is less
447 // than the bundle size), but for now we don't.
448 //
449 if (Assembler.isBundlingEnabled() && F->hasInstructions()) {
450 assert(isa<MCEncodedFragment>(F) &&
451 "Only MCEncodedFragment implementations have instructions");
452 MCEncodedFragment *EF = cast<MCEncodedFragment>(F);
453 uint64_t FSize = Assembler.computeFragmentSize(*this, *EF);
454
455 if (!Assembler.getRelaxAll() && FSize > Assembler.getBundleAlignSize())
456 report_fatal_error("Fragment can't be larger than a bundle size");
457
458 uint64_t RequiredBundlePadding =
459 computeBundlePadding(Assembler, EF, EF->Offset, FSize);
460 if (RequiredBundlePadding > UINT8_MAX)
461 report_fatal_error("Padding cannot exceed 255 bytes");
462 EF->setBundlePadding(static_cast<uint8_t>(RequiredBundlePadding));
463 EF->Offset += RequiredBundlePadding;
464 }
465}
466
467void MCAssembler::registerSymbol(const MCSymbol &Symbol, bool *Created) {
468 bool New = !Symbol.isRegistered();
469 if (Created)
470 *Created = New;
471 if (New) {
472 Symbol.setIsRegistered(true);
473 Symbols.push_back(&Symbol);
474 }
475}
476
478 const MCEncodedFragment &EF,
479 uint64_t FSize) const {
480 assert(getBackendPtr() && "Expected assembler backend");
481 // Should NOP padding be written out before this fragment?
482 unsigned BundlePadding = EF.getBundlePadding();
483 if (BundlePadding > 0) {
485 "Writing bundle padding with disabled bundling");
486 assert(EF.hasInstructions() &&
487 "Writing bundle padding for a fragment without instructions");
488
489 unsigned TotalLength = BundlePadding + static_cast<unsigned>(FSize);
490 const MCSubtargetInfo *STI = EF.getSubtargetInfo();
491 if (EF.alignToBundleEnd() && TotalLength > getBundleAlignSize()) {
492 // If the padding itself crosses a bundle boundary, it must be emitted
493 // in 2 pieces, since even nop instructions must not cross boundaries.
494 // v--------------v <- BundleAlignSize
495 // v---------v <- BundlePadding
496 // ----------------------------
497 // | Prev |####|####| F |
498 // ----------------------------
499 // ^-------------------^ <- TotalLength
500 unsigned DistanceToBoundary = TotalLength - getBundleAlignSize();
501 if (!getBackend().writeNopData(OS, DistanceToBoundary, STI))
502 report_fatal_error("unable to write NOP sequence of " +
503 Twine(DistanceToBoundary) + " bytes");
504 BundlePadding -= DistanceToBoundary;
505 }
506 if (!getBackend().writeNopData(OS, BundlePadding, STI))
507 report_fatal_error("unable to write NOP sequence of " +
508 Twine(BundlePadding) + " bytes");
509 }
510}
511
512/// Write the fragment \p F to the output file.
513static void writeFragment(raw_ostream &OS, const MCAssembler &Asm,
514 const MCAsmLayout &Layout, const MCFragment &F) {
515 // FIXME: Embed in fragments instead?
516 uint64_t FragmentSize = Asm.computeFragmentSize(Layout, F);
517
518 support::endianness Endian = Asm.getBackend().Endian;
519
520 if (const MCEncodedFragment *EF = dyn_cast<MCEncodedFragment>(&F))
521 Asm.writeFragmentPadding(OS, *EF, FragmentSize);
522
523 // This variable (and its dummy usage) is to participate in the assert at
524 // the end of the function.
525 uint64_t Start = OS.tell();
526 (void) Start;
527
528 ++stats::EmittedFragments;
529
530 switch (F.getKind()) {
532 ++stats::EmittedAlignFragments;
533 const MCAlignFragment &AF = cast<MCAlignFragment>(F);
534 assert(AF.getValueSize() && "Invalid virtual align in concrete fragment!");
535
536 uint64_t Count = FragmentSize / AF.getValueSize();
537
538 // FIXME: This error shouldn't actually occur (the front end should emit
539 // multiple .align directives to enforce the semantics it wants), but is
540 // severe enough that we want to report it. How to handle this?
541 if (Count * AF.getValueSize() != FragmentSize)
542 report_fatal_error("undefined .align directive, value size '" +
543 Twine(AF.getValueSize()) +
544 "' is not a divisor of padding size '" +
545 Twine(FragmentSize) + "'");
546
547 // See if we are aligning with nops, and if so do that first to try to fill
548 // the Count bytes. Then if that did not fill any bytes or there are any
549 // bytes left to fill use the Value and ValueSize to fill the rest.
550 // If we are aligning with nops, ask that target to emit the right data.
551 if (AF.hasEmitNops()) {
552 if (!Asm.getBackend().writeNopData(OS, Count, AF.getSubtargetInfo()))
553 report_fatal_error("unable to write nop sequence of " +
554 Twine(Count) + " bytes");
555 break;
556 }
557
558 // Otherwise, write out in multiples of the value size.
559 for (uint64_t i = 0; i != Count; ++i) {
560 switch (AF.getValueSize()) {
561 default: llvm_unreachable("Invalid size!");
562 case 1: OS << char(AF.getValue()); break;
563 case 2:
564 support::endian::write<uint16_t>(OS, AF.getValue(), Endian);
565 break;
566 case 4:
567 support::endian::write<uint32_t>(OS, AF.getValue(), Endian);
568 break;
569 case 8:
570 support::endian::write<uint64_t>(OS, AF.getValue(), Endian);
571 break;
572 }
573 }
574 break;
575 }
576
578 ++stats::EmittedDataFragments;
579 OS << cast<MCDataFragment>(F).getContents();
580 break;
581
583 ++stats::EmittedRelaxableFragments;
584 OS << cast<MCRelaxableFragment>(F).getContents();
585 break;
586
588 ++stats::EmittedCompactEncodedInstFragments;
589 OS << cast<MCCompactEncodedInstFragment>(F).getContents();
590 break;
591
592 case MCFragment::FT_Fill: {
593 ++stats::EmittedFillFragments;
594 const MCFillFragment &FF = cast<MCFillFragment>(F);
595 uint64_t V = FF.getValue();
596 unsigned VSize = FF.getValueSize();
597 const unsigned MaxChunkSize = 16;
598 char Data[MaxChunkSize];
599 assert(0 < VSize && VSize <= MaxChunkSize && "Illegal fragment fill size");
600 // Duplicate V into Data as byte vector to reduce number of
601 // writes done. As such, do endian conversion here.
602 for (unsigned I = 0; I != VSize; ++I) {
603 unsigned index = Endian == support::little ? I : (VSize - I - 1);
604 Data[I] = uint8_t(V >> (index * 8));
605 }
606 for (unsigned I = VSize; I < MaxChunkSize; ++I)
607 Data[I] = Data[I - VSize];
608
609 // Set to largest multiple of VSize in Data.
610 const unsigned NumPerChunk = MaxChunkSize / VSize;
611 // Set ChunkSize to largest multiple of VSize in Data
612 const unsigned ChunkSize = VSize * NumPerChunk;
613
614 // Do copies by chunk.
615 StringRef Ref(Data, ChunkSize);
616 for (uint64_t I = 0, E = FragmentSize / ChunkSize; I != E; ++I)
617 OS << Ref;
618
619 // do remainder if needed.
620 unsigned TrailingCount = FragmentSize % ChunkSize;
621 if (TrailingCount)
622 OS.write(Data, TrailingCount);
623 break;
624 }
625
626 case MCFragment::FT_Nops: {
627 ++stats::EmittedNopsFragments;
628 const MCNopsFragment &NF = cast<MCNopsFragment>(F);
629
630 int64_t NumBytes = NF.getNumBytes();
631 int64_t ControlledNopLength = NF.getControlledNopLength();
632 int64_t MaximumNopLength =
633 Asm.getBackend().getMaximumNopSize(*NF.getSubtargetInfo());
634
635 assert(NumBytes > 0 && "Expected positive NOPs fragment size");
636 assert(ControlledNopLength >= 0 && "Expected non-negative NOP size");
637
638 if (ControlledNopLength > MaximumNopLength) {
639 Asm.getContext().reportError(NF.getLoc(),
640 "illegal NOP size " +
641 std::to_string(ControlledNopLength) +
642 ". (expected within [0, " +
643 std::to_string(MaximumNopLength) + "])");
644 // Clamp the NOP length as reportError does not stop the execution
645 // immediately.
646 ControlledNopLength = MaximumNopLength;
647 }
648
649 // Use maximum value if the size of each NOP is not specified
650 if (!ControlledNopLength)
651 ControlledNopLength = MaximumNopLength;
652
653 while (NumBytes) {
654 uint64_t NumBytesToEmit =
655 (uint64_t)std::min(NumBytes, ControlledNopLength);
656 assert(NumBytesToEmit && "try to emit empty NOP instruction");
657 if (!Asm.getBackend().writeNopData(OS, NumBytesToEmit,
658 NF.getSubtargetInfo())) {
659 report_fatal_error("unable to write nop sequence of the remaining " +
660 Twine(NumBytesToEmit) + " bytes");
661 break;
662 }
663 NumBytes -= NumBytesToEmit;
664 }
665 break;
666 }
667
668 case MCFragment::FT_LEB: {
669 const MCLEBFragment &LF = cast<MCLEBFragment>(F);
670 OS << LF.getContents();
671 break;
672 }
673
675 const MCBoundaryAlignFragment &BF = cast<MCBoundaryAlignFragment>(F);
676 if (!Asm.getBackend().writeNopData(OS, FragmentSize, BF.getSubtargetInfo()))
677 report_fatal_error("unable to write nop sequence of " +
678 Twine(FragmentSize) + " bytes");
679 break;
680 }
681
683 const MCSymbolIdFragment &SF = cast<MCSymbolIdFragment>(F);
684 support::endian::write<uint32_t>(OS, SF.getSymbol()->getIndex(), Endian);
685 break;
686 }
687
688 case MCFragment::FT_Org: {
689 ++stats::EmittedOrgFragments;
690 const MCOrgFragment &OF = cast<MCOrgFragment>(F);
691
692 for (uint64_t i = 0, e = FragmentSize; i != e; ++i)
693 OS << char(OF.getValue());
694
695 break;
696 }
697
699 const MCDwarfLineAddrFragment &OF = cast<MCDwarfLineAddrFragment>(F);
700 OS << OF.getContents();
701 break;
702 }
704 const MCDwarfCallFrameFragment &CF = cast<MCDwarfCallFrameFragment>(F);
705 OS << CF.getContents();
706 break;
707 }
709 const auto &OF = cast<MCCVInlineLineTableFragment>(F);
710 OS << OF.getContents();
711 break;
712 }
714 const auto &DRF = cast<MCCVDefRangeFragment>(F);
715 OS << DRF.getContents();
716 break;
717 }
719 const MCPseudoProbeAddrFragment &PF = cast<MCPseudoProbeAddrFragment>(F);
720 OS << PF.getContents();
721 break;
722 }
724 llvm_unreachable("Should not have been added");
725 }
726
727 assert(OS.tell() - Start == FragmentSize &&
728 "The stream should advance by fragment size");
729}
730
732 const MCAsmLayout &Layout) const {
733 assert(getBackendPtr() && "Expected assembler backend");
734
735 // Ignore virtual sections.
736 if (Sec->isVirtualSection()) {
737 assert(Layout.getSectionFileSize(Sec) == 0 && "Invalid size for section!");
738
739 // Check that contents are only things legal inside a virtual section.
740 for (const MCFragment &F : *Sec) {
741 switch (F.getKind()) {
742 default: llvm_unreachable("Invalid fragment in virtual section!");
743 case MCFragment::FT_Data: {
744 // Check that we aren't trying to write a non-zero contents (or fixups)
745 // into a virtual section. This is to support clients which use standard
746 // directives to fill the contents of virtual sections.
747 const MCDataFragment &DF = cast<MCDataFragment>(F);
748 if (DF.fixup_begin() != DF.fixup_end())
749 getContext().reportError(SMLoc(), Sec->getVirtualSectionKind() +
750 " section '" + Sec->getName() +
751 "' cannot have fixups");
752 for (unsigned i = 0, e = DF.getContents().size(); i != e; ++i)
753 if (DF.getContents()[i]) {
755 Sec->getVirtualSectionKind() +
756 " section '" + Sec->getName() +
757 "' cannot have non-zero initializers");
758 break;
759 }
760 break;
761 }
763 // Check that we aren't trying to write a non-zero value into a virtual
764 // section.
765 assert((cast<MCAlignFragment>(F).getValueSize() == 0 ||
766 cast<MCAlignFragment>(F).getValue() == 0) &&
767 "Invalid align in virtual section!");
768 break;
770 assert((cast<MCFillFragment>(F).getValue() == 0) &&
771 "Invalid fill in virtual section!");
772 break;
774 break;
775 }
776 }
777
778 return;
779 }
780
781 uint64_t Start = OS.tell();
782 (void)Start;
783
784 for (const MCFragment &F : *Sec)
785 writeFragment(OS, *this, Layout, F);
786
787 assert(getContext().hadError() ||
788 OS.tell() - Start == Layout.getSectionAddressSize(Sec));
789}
790
791std::tuple<MCValue, uint64_t, bool>
792MCAssembler::handleFixup(const MCAsmLayout &Layout, MCFragment &F,
793 const MCFixup &Fixup) {
794 // Evaluate the fixup.
796 uint64_t FixedValue;
797 bool WasForced;
798 bool IsResolved = evaluateFixup(Layout, Fixup, &F, Target, FixedValue,
799 WasForced);
800 if (!IsResolved) {
801 // The fixup was unresolved, we need a relocation. Inform the object
802 // writer of the relocation, and give it an opportunity to adjust the
803 // fixup value if need be.
804 getWriter().recordRelocation(*this, Layout, &F, Fixup, Target, FixedValue);
805 }
806 return std::make_tuple(Target, FixedValue, IsResolved);
807}
808
810 assert(getBackendPtr() && "Expected assembler backend");
811 DEBUG_WITH_TYPE("mc-dump", {
812 errs() << "assembler backend - pre-layout\n--\n";
813 dump(); });
814
815 // Create dummy fragments and assign section ordinals.
816 unsigned SectionIndex = 0;
817 for (MCSection &Sec : *this) {
818 // Create dummy fragments to eliminate any empty sections, this simplifies
819 // layout.
820 if (Sec.getFragmentList().empty())
821 new MCDataFragment(&Sec);
822
823 Sec.setOrdinal(SectionIndex++);
824 }
825
826 // Assign layout order indices to sections and fragments.
827 for (unsigned i = 0, e = Layout.getSectionOrder().size(); i != e; ++i) {
828 MCSection *Sec = Layout.getSectionOrder()[i];
829 Sec->setLayoutOrder(i);
830
831 unsigned FragmentIndex = 0;
832 for (MCFragment &Frag : *Sec)
833 Frag.setLayoutOrder(FragmentIndex++);
834 }
835
836 // Layout until everything fits.
837 while (layoutOnce(Layout)) {
838 if (getContext().hadError())
839 return;
840 // Size of fragments in one section can depend on the size of fragments in
841 // another. If any fragment has changed size, we have to re-layout (and
842 // as a result possibly further relax) all.
843 for (MCSection &Sec : *this)
844 Layout.invalidateFragmentsFrom(&*Sec.begin());
845 }
846
847 DEBUG_WITH_TYPE("mc-dump", {
848 errs() << "assembler backend - post-relaxation\n--\n";
849 dump(); });
850
851 // Finalize the layout, including fragment lowering.
852 finishLayout(Layout);
853
854 DEBUG_WITH_TYPE("mc-dump", {
855 errs() << "assembler backend - final-layout\n--\n";
856 dump(); });
857
858 // Allow the object writer a chance to perform post-layout binding (for
859 // example, to set the index fields in the symbol data).
860 getWriter().executePostLayoutBinding(*this, Layout);
861
862 // Evaluate and apply the fixups, generating relocation entries as necessary.
863 for (MCSection &Sec : *this) {
864 for (MCFragment &Frag : Sec) {
865 ArrayRef<MCFixup> Fixups;
866 MutableArrayRef<char> Contents;
867 const MCSubtargetInfo *STI = nullptr;
868
869 // Process MCAlignFragment and MCEncodedFragmentWithFixups here.
870 switch (Frag.getKind()) {
871 default:
872 continue;
874 MCAlignFragment &AF = cast<MCAlignFragment>(Frag);
875 // Insert fixup type for code alignment if the target define
876 // shouldInsertFixupForCodeAlign target hook.
877 if (Sec.useCodeAlign() && AF.hasEmitNops())
878 getBackend().shouldInsertFixupForCodeAlign(*this, Layout, AF);
879 continue;
880 }
881 case MCFragment::FT_Data: {
882 MCDataFragment &DF = cast<MCDataFragment>(Frag);
883 Fixups = DF.getFixups();
884 Contents = DF.getContents();
885 STI = DF.getSubtargetInfo();
886 assert(!DF.hasInstructions() || STI != nullptr);
887 break;
888 }
890 MCRelaxableFragment &RF = cast<MCRelaxableFragment>(Frag);
891 Fixups = RF.getFixups();
892 Contents = RF.getContents();
893 STI = RF.getSubtargetInfo();
894 assert(!RF.hasInstructions() || STI != nullptr);
895 break;
896 }
898 MCCVDefRangeFragment &CF = cast<MCCVDefRangeFragment>(Frag);
899 Fixups = CF.getFixups();
900 Contents = CF.getContents();
901 break;
902 }
904 MCDwarfLineAddrFragment &DF = cast<MCDwarfLineAddrFragment>(Frag);
905 Fixups = DF.getFixups();
906 Contents = DF.getContents();
907 break;
908 }
910 MCDwarfCallFrameFragment &DF = cast<MCDwarfCallFrameFragment>(Frag);
911 Fixups = DF.getFixups();
912 Contents = DF.getContents();
913 break;
914 }
916 MCPseudoProbeAddrFragment &PF = cast<MCPseudoProbeAddrFragment>(Frag);
917 Fixups = PF.getFixups();
918 Contents = PF.getContents();
919 break;
920 }
921 }
922 for (const MCFixup &Fixup : Fixups) {
923 uint64_t FixedValue;
924 bool IsResolved;
926 std::tie(Target, FixedValue, IsResolved) =
927 handleFixup(Layout, Frag, Fixup);
928 getBackend().applyFixup(*this, Fixup, Target, Contents, FixedValue,
929 IsResolved, STI);
930 }
931 }
932 }
933}
934
936 // Create the layout object.
937 MCAsmLayout Layout(*this);
938 layout(Layout);
939
940 // Write the object file.
941 stats::ObjectBytes += getWriter().writeObject(*this, Layout);
942}
943
944bool MCAssembler::fixupNeedsRelaxation(const MCFixup &Fixup,
945 const MCRelaxableFragment *DF,
946 const MCAsmLayout &Layout) const {
947 assert(getBackendPtr() && "Expected assembler backend");
950 bool WasForced;
951 bool Resolved = evaluateFixup(Layout, Fixup, DF, Target, Value, WasForced);
952 if (Target.getSymA() &&
953 Target.getSymA()->getKind() == MCSymbolRefExpr::VK_X86_ABS8 &&
954 Fixup.getKind() == FK_Data_1)
955 return false;
957 Layout, WasForced);
958}
959
960bool MCAssembler::fragmentNeedsRelaxation(const MCRelaxableFragment *F,
961 const MCAsmLayout &Layout) const {
962 assert(getBackendPtr() && "Expected assembler backend");
963 // If this inst doesn't ever need relaxation, ignore it. This occurs when we
964 // are intentionally pushing out inst fragments, or because we relaxed a
965 // previous instruction to one that doesn't need relaxation.
966 if (!getBackend().mayNeedRelaxation(F->getInst(), *F->getSubtargetInfo()))
967 return false;
968
969 for (const MCFixup &Fixup : F->getFixups())
970 if (fixupNeedsRelaxation(Fixup, F, Layout))
971 return true;
972
973 return false;
974}
975
976bool MCAssembler::relaxInstruction(MCAsmLayout &Layout,
979 "Expected CodeEmitter defined for relaxInstruction");
980 if (!fragmentNeedsRelaxation(&F, Layout))
981 return false;
982
983 ++stats::RelaxedInstructions;
984
985 // FIXME-PERF: We could immediately lower out instructions if we can tell
986 // they are fully resolved, to avoid retesting on later passes.
987
988 // Relax the fragment.
989
990 MCInst Relaxed = F.getInst();
991 getBackend().relaxInstruction(Relaxed, *F.getSubtargetInfo());
992
993 // Encode the new instruction.
994 //
995 // FIXME-PERF: If it matters, we could let the target do this. It can
996 // probably do so more efficiently in many cases.
999 raw_svector_ostream VecOS(Code);
1000 getEmitter().encodeInstruction(Relaxed, VecOS, Fixups, *F.getSubtargetInfo());
1001
1002 // Update the fragment.
1003 F.setInst(Relaxed);
1004 F.getContents() = Code;
1005 F.getFixups() = Fixups;
1006
1007 return true;
1008}
1009
1010bool MCAssembler::relaxLEB(MCAsmLayout &Layout, MCLEBFragment &LF) {
1011 uint64_t OldSize = LF.getContents().size();
1012 int64_t Value;
1013 bool Abs = LF.getValue().evaluateKnownAbsolute(Value, Layout);
1014 if (!Abs)
1015 report_fatal_error("sleb128 and uleb128 expressions must be absolute");
1017 Data.clear();
1019 // The compiler can generate EH table assembly that is impossible to assemble
1020 // without either adding padding to an LEB fragment or adding extra padding
1021 // to a later alignment fragment. To accommodate such tables, relaxation can
1022 // only increase an LEB fragment size here, not decrease it. See PR35809.
1023 if (LF.isSigned())
1024 encodeSLEB128(Value, OSE, OldSize);
1025 else
1026 encodeULEB128(Value, OSE, OldSize);
1027 return OldSize != LF.getContents().size();
1028}
1029
1030/// Check if the branch crosses the boundary.
1031///
1032/// \param StartAddr start address of the fused/unfused branch.
1033/// \param Size size of the fused/unfused branch.
1034/// \param BoundaryAlignment alignment requirement of the branch.
1035/// \returns true if the branch cross the boundary.
1037 Align BoundaryAlignment) {
1038 uint64_t EndAddr = StartAddr + Size;
1039 return (StartAddr >> Log2(BoundaryAlignment)) !=
1040 ((EndAddr - 1) >> Log2(BoundaryAlignment));
1041}
1042
1043/// Check if the branch is against the boundary.
1044///
1045/// \param StartAddr start address of the fused/unfused branch.
1046/// \param Size size of the fused/unfused branch.
1047/// \param BoundaryAlignment alignment requirement of the branch.
1048/// \returns true if the branch is against the boundary.
1050 Align BoundaryAlignment) {
1051 uint64_t EndAddr = StartAddr + Size;
1052 return (EndAddr & (BoundaryAlignment.value() - 1)) == 0;
1053}
1054
1055/// Check if the branch needs padding.
1056///
1057/// \param StartAddr start address of the fused/unfused branch.
1058/// \param Size size of the fused/unfused branch.
1059/// \param BoundaryAlignment alignment requirement of the branch.
1060/// \returns true if the branch needs padding.
1061static bool needPadding(uint64_t StartAddr, uint64_t Size,
1062 Align BoundaryAlignment) {
1063 return mayCrossBoundary(StartAddr, Size, BoundaryAlignment) ||
1064 isAgainstBoundary(StartAddr, Size, BoundaryAlignment);
1065}
1066
1067bool MCAssembler::relaxBoundaryAlign(MCAsmLayout &Layout,
1069 // BoundaryAlignFragment that doesn't need to align any fragment should not be
1070 // relaxed.
1071 if (!BF.getLastFragment())
1072 return false;
1073
1074 uint64_t AlignedOffset = Layout.getFragmentOffset(&BF);
1075 uint64_t AlignedSize = 0;
1076 for (const MCFragment *F = BF.getLastFragment(); F != &BF;
1077 F = F->getPrevNode())
1078 AlignedSize += computeFragmentSize(Layout, *F);
1079
1080 Align BoundaryAlignment = BF.getAlignment();
1081 uint64_t NewSize = needPadding(AlignedOffset, AlignedSize, BoundaryAlignment)
1082 ? offsetToAlignment(AlignedOffset, BoundaryAlignment)
1083 : 0U;
1084 if (NewSize == BF.getSize())
1085 return false;
1086 BF.setSize(NewSize);
1087 Layout.invalidateFragmentsFrom(&BF);
1088 return true;
1089}
1090
1091bool MCAssembler::relaxDwarfLineAddr(MCAsmLayout &Layout,
1093
1094 bool WasRelaxed;
1095 if (getBackend().relaxDwarfLineAddr(DF, Layout, WasRelaxed))
1096 return WasRelaxed;
1097
1098 MCContext &Context = Layout.getAssembler().getContext();
1099 uint64_t OldSize = DF.getContents().size();
1100 int64_t AddrDelta;
1101 bool Abs = DF.getAddrDelta().evaluateKnownAbsolute(AddrDelta, Layout);
1102 assert(Abs && "We created a line delta with an invalid expression");
1103 (void)Abs;
1104 int64_t LineDelta;
1105 LineDelta = DF.getLineDelta();
1106 SmallVectorImpl<char> &Data = DF.getContents();
1107 Data.clear();
1109 DF.getFixups().clear();
1110
1112 AddrDelta, OSE);
1113 return OldSize != Data.size();
1114}
1115
1116bool MCAssembler::relaxDwarfCallFrameFragment(MCAsmLayout &Layout,
1118 bool WasRelaxed;
1119 if (getBackend().relaxDwarfCFA(DF, Layout, WasRelaxed))
1120 return WasRelaxed;
1121
1123 uint64_t OldSize = DF.getContents().size();
1124 int64_t AddrDelta;
1125 bool Abs = DF.getAddrDelta().evaluateKnownAbsolute(AddrDelta, Layout);
1126 assert(Abs && "We created call frame with an invalid expression");
1127 (void) Abs;
1128 SmallVectorImpl<char> &Data = DF.getContents();
1129 Data.clear();
1131 DF.getFixups().clear();
1132
1133 MCDwarfFrameEmitter::EncodeAdvanceLoc(Context, AddrDelta, OSE);
1134 return OldSize != Data.size();
1135}
1136
1137bool MCAssembler::relaxCVInlineLineTable(MCAsmLayout &Layout,
1139 unsigned OldSize = F.getContents().size();
1141 return OldSize != F.getContents().size();
1142}
1143
1144bool MCAssembler::relaxCVDefRange(MCAsmLayout &Layout,
1146 unsigned OldSize = F.getContents().size();
1148 return OldSize != F.getContents().size();
1149}
1150
1151bool MCAssembler::relaxPseudoProbeAddr(MCAsmLayout &Layout,
1153 uint64_t OldSize = PF.getContents().size();
1154 int64_t AddrDelta;
1155 bool Abs = PF.getAddrDelta().evaluateKnownAbsolute(AddrDelta, Layout);
1156 assert(Abs && "We created a pseudo probe with an invalid expression");
1157 (void)Abs;
1159 Data.clear();
1161 PF.getFixups().clear();
1162
1163 // AddrDelta is a signed integer
1164 encodeSLEB128(AddrDelta, OSE, OldSize);
1165 return OldSize != Data.size();
1166}
1167
1168bool MCAssembler::relaxFragment(MCAsmLayout &Layout, MCFragment &F) {
1169 switch(F.getKind()) {
1170 default:
1171 return false;
1173 assert(!getRelaxAll() &&
1174 "Did not expect a MCRelaxableFragment in RelaxAll mode");
1175 return relaxInstruction(Layout, cast<MCRelaxableFragment>(F));
1177 return relaxDwarfLineAddr(Layout, cast<MCDwarfLineAddrFragment>(F));
1179 return relaxDwarfCallFrameFragment(Layout,
1180 cast<MCDwarfCallFrameFragment>(F));
1181 case MCFragment::FT_LEB:
1182 return relaxLEB(Layout, cast<MCLEBFragment>(F));
1184 return relaxBoundaryAlign(Layout, cast<MCBoundaryAlignFragment>(F));
1186 return relaxCVInlineLineTable(Layout, cast<MCCVInlineLineTableFragment>(F));
1188 return relaxCVDefRange(Layout, cast<MCCVDefRangeFragment>(F));
1190 return relaxPseudoProbeAddr(Layout, cast<MCPseudoProbeAddrFragment>(F));
1191 }
1192}
1193
1194bool MCAssembler::layoutSectionOnce(MCAsmLayout &Layout, MCSection &Sec) {
1195 // Holds the first fragment which needed relaxing during this layout. It will
1196 // remain NULL if none were relaxed.
1197 // When a fragment is relaxed, all the fragments following it should get
1198 // invalidated because their offset is going to change.
1199 MCFragment *FirstRelaxedFragment = nullptr;
1200
1201 // Attempt to relax all the fragments in the section.
1202 for (MCFragment &Frag : Sec) {
1203 // Check if this is a fragment that needs relaxation.
1204 bool RelaxedFrag = relaxFragment(Layout, Frag);
1205 if (RelaxedFrag && !FirstRelaxedFragment)
1206 FirstRelaxedFragment = &Frag;
1207 }
1208 if (FirstRelaxedFragment) {
1209 Layout.invalidateFragmentsFrom(FirstRelaxedFragment);
1210 return true;
1211 }
1212 return false;
1213}
1214
1215bool MCAssembler::layoutOnce(MCAsmLayout &Layout) {
1216 ++stats::RelaxationSteps;
1217
1218 bool WasRelaxed = false;
1219 for (MCSection &Sec : *this) {
1220 while (layoutSectionOnce(Layout, Sec))
1221 WasRelaxed = true;
1222 }
1223
1224 return WasRelaxed;
1225}
1226
1227void MCAssembler::finishLayout(MCAsmLayout &Layout) {
1228 assert(getBackendPtr() && "Expected assembler backend");
1229 // The layout is done. Mark every fragment as valid.
1230 for (unsigned int i = 0, n = Layout.getSectionOrder().size(); i != n; ++i) {
1231 MCSection &Section = *Layout.getSectionOrder()[i];
1232 Layout.getFragmentOffset(&*Section.getFragmentList().rbegin());
1233 computeFragmentSize(Layout, *Section.getFragmentList().rbegin());
1234 }
1235 getBackend().finishLayout(*this, Layout);
1236}
1237
1238#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1240 raw_ostream &OS = errs();
1241
1242 OS << "<MCAssembler\n";
1243 OS << " Sections:[\n ";
1244 for (const_iterator it = begin(), ie = end(); it != ie; ++it) {
1245 if (it != begin()) OS << ",\n ";
1246 it->dump();
1247 }
1248 OS << "],\n";
1249 OS << " Symbols:[";
1250
1251 for (const_symbol_iterator it = symbol_begin(), ie = symbol_end(); it != ie; ++it) {
1252 if (it != symbol_begin()) OS << ",\n ";
1253 OS << "(";
1254 it->dump();
1255 OS << ", Index:" << it->getIndex() << ", ";
1256 OS << ")";
1257 }
1258 OS << "]>\n";
1259}
1260#endif
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
static GCRegistry::Add< ErlangGC > A("erlang", "erlang-compatible garbage collector")
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
#define LLVM_DUMP_METHOD
Mark debug helper function definitions like dump() that should not be stripped from debug builds.
Definition: Compiler.h:492
dxil DXContainer Global Emitter
#define DEBUG_WITH_TYPE(TYPE, X)
DEBUG_WITH_TYPE macro - This macro should be used by passes to emit debug information.
Definition: Debug.h:64
static RegisterPass< DebugifyFunctionPass > DF("debugify-function", "Attach debug info to a function")
uint64_t Size
static void writeFragment(raw_ostream &OS, const MCAssembler &Asm, const MCAsmLayout &Layout, const MCFragment &F)
Write the fragment F to the output file.
static bool needPadding(uint64_t StartAddr, uint64_t Size, Align BoundaryAlignment)
Check if the branch needs padding.
static bool mayCrossBoundary(uint64_t StartAddr, uint64_t Size, Align BoundaryAlignment)
Check if the branch crosses the boundary.
static bool isAgainstBoundary(uint64_t StartAddr, uint64_t Size, Align BoundaryAlignment)
Check if the branch is against the boundary.
#define F(x, y, z)
Definition: MD5.cpp:55
#define I(x, y, z)
Definition: MD5.cpp:58
LLVMContext & Context
PowerPC TLS Dynamic Call Fixup
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
This file defines the SmallString class.
This file defines the SmallVector class.
This file defines the 'Statistic' class, which is designed to be an easy way to expose various metric...
#define STATISTIC(VARNAME, DESC)
Definition: Statistic.h:167
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory),...
Definition: ArrayRef.h:41
void encodeInlineLineTable(MCAsmLayout &Layout, MCCVInlineLineTableFragment &F)
Encodes the binary annotations once we have a layout.
Definition: MCCodeView.cpp:462
void encodeDefRange(MCAsmLayout &Layout, MCCVDefRangeFragment &F)
Definition: MCCodeView.cpp:606
int64_t getValue() const
Definition: MCFragment.h:324
Align getAlignment() const
Definition: MCFragment.h:322
unsigned getMaxBytesToEmit() const
Definition: MCFragment.h:328
bool hasEmitNops() const
Definition: MCFragment.h:330
unsigned getValueSize() const
Definition: MCFragment.h:326
const MCSubtargetInfo * getSubtargetInfo() const
Definition: MCFragment.h:336
virtual bool fixupNeedsRelaxationAdvanced(const MCFixup &Fixup, bool Resolved, uint64_t Value, const MCRelaxableFragment *DF, const MCAsmLayout &Layout, const bool WasForced) const
Target specific predicate for whether a given fixup requires the associated instruction to be relaxed...
virtual bool evaluateTargetFixup(const MCAssembler &Asm, const MCAsmLayout &Layout, const MCFixup &Fixup, const MCFragment *DF, const MCValue &Target, uint64_t &Value, bool &WasForced)
Definition: MCAsmBackend.h:119
virtual bool shouldInsertFixupForCodeAlign(MCAssembler &Asm, const MCAsmLayout &Layout, MCAlignFragment &AF)
Hook which indicates if the target requires a fixup to be generated when handling an align directive ...
Definition: MCAsmBackend.h:113
virtual void relaxInstruction(MCInst &Inst, const MCSubtargetInfo &STI) const
Relax the instruction in the given fragment to the next wider instruction.
Definition: MCAsmBackend.h:171
virtual void finishLayout(MCAssembler const &Asm, MCAsmLayout &Layout) const
Give backend an opportunity to finish layout after relaxation.
Definition: MCAsmBackend.h:206
virtual void reset()
lifetime management
Definition: MCAsmBackend.h:68
virtual const MCFixupKindInfo & getFixupKindInfo(MCFixupKind Kind) const
Get information on a fixup kind.
virtual void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup, const MCValue &Target, MutableArrayRef< char > Data, uint64_t Value, bool IsResolved, const MCSubtargetInfo *STI) const =0
Apply the Value for given Fixup into the provided data fragment, at the offset specified by the fixup...
Encapsulates the layout of an assembly file at a particular point in time.
Definition: MCAsmLayout.h:28
void invalidateFragmentsFrom(MCFragment *F)
Invalidate the fragments starting with F because it has been resized.
Definition: MCFragment.cpp:70
uint64_t getSectionAddressSize(const MCSection *Sec) const
Get the address space size of the given section, as it effects layout.
Definition: MCFragment.cpp:198
llvm::SmallVectorImpl< MCSection * > & getSectionOrder()
Definition: MCAsmLayout.h:69
uint64_t getSectionFileSize(const MCSection *Sec) const
Get the data size of the given section, as emitted to the object file.
Definition: MCFragment.cpp:204
bool getSymbolOffset(const MCSymbol &S, uint64_t &Val) const
Get the offset of the given symbol, as computed in the current layout.
Definition: MCFragment.cpp:152
void layoutFragment(MCFragment *Fragment)
Perform layout for a single fragment, assuming that the previous fragment has already been laid out c...
uint64_t getFragmentOffset(const MCFragment *F) const
Get the offset of the given fragment inside its containing section.
Definition: MCFragment.cpp:96
MCAssembler & getAssembler() const
Get the assembler object this is a layout for.
Definition: MCAsmLayout.h:50
MCContext & getContext() const
Definition: MCAssembler.h:321
void registerSymbol(const MCSymbol &Symbol, bool *Created=nullptr)
void Finish()
Finish - Do final processing and write the object to the output stream.
void writeSectionData(raw_ostream &OS, const MCSection *Section, const MCAsmLayout &Layout) const
Emit the section contents to OS.
unsigned getBundleAlignSize() const
Definition: MCAssembler.h:362
bool isBundlingEnabled() const
Definition: MCAssembler.h:360
symbol_iterator symbol_begin()
Definition: MCAssembler.h:384
void dump() const
void layout(MCAsmLayout &Layout)
MCObjectWriter * getWriterPtr() const
Definition: MCAssembler.h:327
MCObjectWriter & getWriter() const
Definition: MCAssembler.h:333
uint64_t computeFragmentSize(const MCAsmLayout &Layout, const MCFragment &F) const
Compute the effective fragment size assuming it is laid out at the given SectionAddress and FragmentO...
MCCodeEmitter * getEmitterPtr() const
Definition: MCAssembler.h:325
bool getRelaxAll() const
Definition: MCAssembler.h:357
MCCodeEmitter & getEmitter() const
Definition: MCAssembler.h:331
iterator end()
Definition: MCAssembler.h:376
MCAssembler(MCContext &Context, std::unique_ptr< MCAsmBackend > Backend, std::unique_ptr< MCCodeEmitter > Emitter, std::unique_ptr< MCObjectWriter > Writer)
Construct a new assembler instance.
Definition: MCAssembler.cpp:84
iterator begin()
Definition: MCAssembler.h:373
bool isThumbFunc(const MCSymbol *Func) const
Check whether a given symbol has been flagged with .thumb_func.
MCAsmBackend & getBackend() const
Definition: MCAssembler.h:329
bool registerSection(MCSection &Section)
const MCSymbol * getAtom(const MCSymbol &S) const
Find the symbol which defines the atom containing the given symbol, or null if there is no such symbo...
MCAsmBackend * getBackendPtr() const
Definition: MCAssembler.h:323
bool isSymbolLinkerVisible(const MCSymbol &SD) const
Check whether a particular symbol is visible to the linker and is required in the symbol table,...
MCLOHContainer & getLOHContainer()
Definition: MCAssembler.h:460
symbol_iterator symbol_end()
Definition: MCAssembler.h:387
void reset()
Reuse an assembler instance.
Definition: MCAssembler.cpp:98
MCDwarfLineTableParams getDWARFLinetableParams() const
Definition: MCAssembler.h:335
void writeFragmentPadding(raw_ostream &OS, const MCEncodedFragment &F, uint64_t FSize) const
Write the necessary bundle padding to OS.
Represents required padding such that a particular other set of fragments does not cross a particular...
Definition: MCFragment.h:578
uint64_t getSize() const
Definition: MCFragment.h:596
void setSize(uint64_t Value)
Definition: MCFragment.h:597
const MCFragment * getLastFragment() const
Definition: MCFragment.h:602
const MCSubtargetInfo * getSubtargetInfo() const
Definition: MCFragment.h:608
Fragment representing the .cv_def_range directive.
Definition: MCFragment.h:548
Fragment representing the binary annotations produced by the .cv_inline_linetable directive.
Definition: MCFragment.h:515
virtual void encodeInstruction(const MCInst &Inst, raw_ostream &OS, SmallVectorImpl< MCFixup > &Fixups, const MCSubtargetInfo &STI) const =0
EncodeInstruction - Encode the given Inst to bytes on the output stream OS.
virtual void reset()
Lifetime management.
Definition: MCCodeEmitter.h:31
Context object for machine code objects.
Definition: MCContext.h:76
bool hadError()
Definition: MCContext.h:848
CodeViewContext & getCVContext()
Definition: MCContext.cpp:1000
void reportError(SMLoc L, const Twine &Msg)
Definition: MCContext.cpp:1055
Fragment for data and encoded instructions.
Definition: MCFragment.h:241
static void EncodeAdvanceLoc(MCContext &Context, uint64_t AddrDelta, raw_ostream &OS)
Definition: MCDwarf.cpp:1929
static void Encode(MCContext &Context, MCDwarfLineTableParams Params, int64_t LineDelta, uint64_t AddrDelta, raw_ostream &OS)
Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
Definition: MCDwarf.cpp:682
SmallVectorImpl< char > & getContents()
Definition: MCFragment.h:196
SmallVectorImpl< MCFixup > & getFixups()
Definition: MCFragment.h:222
Interface implemented by fragments that contain encoded instructions and/or data.
Definition: MCFragment.h:124
const MCSubtargetInfo * getSubtargetInfo() const
Retrieve the MCSubTargetInfo in effect when the instruction was encoded.
Definition: MCFragment.h:172
void setBundlePadding(uint8_t N)
Set the padding size for this fragment.
Definition: MCFragment.h:168
uint8_t getBundlePadding() const
Get the padding size that must be inserted before this fragment.
Definition: MCFragment.h:164
bool alignToBundleEnd() const
Should this fragment be placed at the end of an aligned bundle?
Definition: MCFragment.h:156
Base class for the full range of assembler expressions which are needed for parsing.
Definition: MCExpr.h:35
bool evaluateKnownAbsolute(int64_t &Res, const MCAsmLayout &Layout) const
Definition: MCExpr.cpp:561
bool evaluateAsRelocatable(MCValue &Res, const MCAsmLayout *Layout, const MCFixup *Fixup) const
Try to evaluate the expression to a relocatable value, i.e.
Definition: MCExpr.cpp:749
bool evaluateAsValue(MCValue &Res, const MCAsmLayout &Layout) const
Try to evaluate the expression to the form (a - b + constant) where neither a nor b are variables.
Definition: MCExpr.cpp:757
uint8_t getValueSize() const
Definition: MCFragment.h:360
uint64_t getValue() const
Definition: MCFragment.h:359
Encode information on a single operation to perform on a byte sequence (e.g., an encoded instruction)...
Definition: MCFixup.h:71
const MCSymbol * getAtom() const
Definition: MCFragment.h:98
MCSection * getParent() const
Definition: MCFragment.h:95
bool hasInstructions() const
Does this fragment have instructions emitted into it? By default this is false, but specific fragment...
Definition: MCFragment.h:106
Instances of this class represent a single low-level machine instruction.
Definition: MCInst.h:184
bool isSigned() const
Definition: MCFragment.h:444
const MCExpr & getValue() const
Definition: MCFragment.h:442
SmallString< 8 > & getContents()
Definition: MCFragment.h:446
int64_t getControlledNopLength() const
Definition: MCFragment.h:389
int64_t getNumBytes() const
Definition: MCFragment.h:388
const MCSubtargetInfo * getSubtargetInfo() const
Definition: MCFragment.h:393
SMLoc getLoc() const
Definition: MCFragment.h:391
virtual uint64_t writeObject(MCAssembler &Asm, const MCAsmLayout &Layout)=0
Write the object file and returns the number of bytes written.
virtual void executePostLayoutBinding(MCAssembler &Asm, const MCAsmLayout &Layout)=0
Perform any late binding of symbols (for example, to assign symbol indices for use when generating re...
virtual void reset()
lifetime management
virtual void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout, const MCFragment *Fragment, const MCFixup &Fixup, MCValue Target, uint64_t &FixedValue)=0
Record a relocation entry.
SMLoc getLoc() const
Definition: MCFragment.h:420
uint8_t getValue() const
Definition: MCFragment.h:418
const MCExpr & getOffset() const
Definition: MCFragment.h:416
const MCExpr & getAddrDelta() const
Definition: MCFragment.h:625
A relaxable fragment holds on to its MCInst, since it may need to be relaxed during the assembler lay...
Definition: MCFragment.h:270
Instances of this class represent a uniqued identifier for a section in the current translation unit.
Definition: MCSection.h:39
void setLayoutOrder(unsigned Value)
Definition: MCSection.h:153
MCSection::FragmentListType & getFragmentList()
Definition: MCSection.h:172
virtual bool isVirtualSection() const =0
Check whether this section is "virtual", that is has no actual object file contents.
void setOrdinal(unsigned Value)
Definition: MCSection.h:150
virtual bool useCodeAlign() const =0
Return true if a .align directive should use "optimized nops" to fill instead of 0s.
iterator begin()
Definition: MCSection.h:185
Generic base class for all target subtargets.
Represents a symbol table index fragment.
Definition: MCFragment.h:498
const MCSymbol * getSymbol()
Definition: MCFragment.h:505
Represent a reference to a symbol from inside an expression.
Definition: MCExpr.h:192
MCSymbol - Instances of this class represent a symbol name in the MC file, and MCSymbols are created ...
Definition: MCSymbol.h:41
bool isDefined() const
isDefined - Check if this symbol is defined (i.e., it has an address).
Definition: MCSymbol.h:248
bool isInSection() const
isInSection - Check if this symbol is defined in some section (i.e., it is defined but not absolute).
Definition: MCSymbol.h:252
bool isUndefined(bool SetUsed=true) const
isUndefined - Check if this symbol undefined (i.e., implicitly defined).
Definition: MCSymbol.h:257
uint32_t getIndex() const
Get the (implementation defined) index.
Definition: MCSymbol.h:314
MCFragment * getFragment(bool SetUsed=true) const
Definition: MCSymbol.h:395
This represents an "assembler immediate".
Definition: MCValue.h:36
uint32_t getRefKind() const
Definition: MCValue.h:46
const MCSymbolRefExpr * getSymB() const
Definition: MCValue.h:45
const MCSymbolRefExpr * getSymA() const
Definition: MCValue.h:44
MutableArrayRef - Represent a mutable reference to an array (0 or more elements consecutively in memo...
Definition: ArrayRef.h:305
Represents a location in source code.
Definition: SMLoc.h:23
SmallString - A SmallString is just a SmallVector with methods and accessors that make it work better...
Definition: SmallString.h:26
size_t size() const
Definition: SmallVector.h:91
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: SmallVector.h:577
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small.
Definition: SmallVector.h:1200
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:50
Target - Wrapper for Target specific information.
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:81
LLVM Value Representation.
Definition: Value.h:74
Represents a version number in the form major[.minor[.subminor[.build]]].
Definition: VersionTuple.h:31
This class implements an extremely fast bulk output stream that can only output to a stream.
Definition: raw_ostream.h:52
uint64_t tell() const
tell - Return the current offset with the file.
Definition: raw_ostream.h:134
raw_ostream & write(unsigned char C)
A raw_ostream that writes to an SmallVector or SmallString.
Definition: raw_ostream.h:672
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
@ Offset
Definition: DWP.cpp:406
void report_fatal_error(Error Err, bool gen_crash_diag=true)
Report a serious error, calling any installed error handler.
Definition: Error.cpp:145
@ FK_Data_1
A one-byte fixup.
Definition: MCFixup.h:23
uint64_t computeBundlePadding(const MCAssembler &Assembler, const MCEncodedFragment *F, uint64_t FOffset, uint64_t FSize)
Compute the amount of padding required before the fragment F to obey bundling restrictions,...
Definition: MCFragment.cpp:213
uint64_t offsetToAlignment(uint64_t Value, Align Alignment)
Returns the offset to the next integer (mod 2**64) that is greater than or equal to Value and is a mu...
Definition: Alignment.h:197
raw_fd_ostream & errs()
This returns a reference to a raw_ostream for standard error.
@ Ref
The access may reference the value stored in memory.
OutputIt move(R &&Range, OutputIt Out)
Provide wrappers to std::move which take ranges instead of having to pass begin/end explicitly.
Definition: STLExtras.h:1862
unsigned encodeSLEB128(int64_t Value, raw_ostream &OS, unsigned PadTo=0)
Utility function to encode a SLEB128 value to an output stream.
Definition: LEB128.h:23
unsigned encodeULEB128(uint64_t Value, raw_ostream &OS, unsigned PadTo=0)
Utility function to encode a ULEB128 value to an output stream.
Definition: LEB128.h:80
unsigned Log2(Align A)
Returns the log2 of the alignment.
Definition: Alignment.h:208
Definition: BitVector.h:851
This struct is a compact representation of a valid (non-zero power of two) alignment.
Definition: Alignment.h:39
uint64_t value() const
This is a hole in the type system and should not be abused.
Definition: Alignment.h:85
@ FKF_IsTarget
Should this fixup be evaluated in a target dependent manner?
@ FKF_IsAlignedDownTo32Bits
Should this fixup kind force a 4-byte aligned effective PC value?
@ FKF_Constant
This fixup kind should be resolved if defined.
@ FKF_IsPCRel
Is this fixup kind PCrelative? This is used by the assembler backend to evaluate fixup values in a ta...
unsigned Flags
Flags describing additional information on this fixup kind.
An iterator type that allows iterating over the pointees via some other iterator.
Definition: iterator.h:324