1 //===- lib/MC/MCAssembler.cpp - Assembler Backend Implementation ----------===//
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 #define DEBUG_TYPE "assembler"
11 #include "llvm/MC/MCAssembler.h"
12 #include "llvm/MC/MCAsmLayout.h"
13 #include "llvm/MC/MCCodeEmitter.h"
14 #include "llvm/MC/MCExpr.h"
15 #include "llvm/MC/MCObjectWriter.h"
16 #include "llvm/MC/MCSymbol.h"
17 #include "llvm/MC/MCValue.h"
18 #include "llvm/ADT/OwningPtr.h"
19 #include "llvm/ADT/Statistic.h"
20 #include "llvm/ADT/StringExtras.h"
21 #include "llvm/ADT/Twine.h"
22 #include "llvm/Support/ErrorHandling.h"
23 #include "llvm/Support/raw_ostream.h"
24 #include "llvm/Support/Debug.h"
25 #include "llvm/Target/TargetRegistry.h"
26 #include "llvm/Target/TargetAsmBackend.h"
33 STATISTIC(RelaxedInstructions, "Number of relaxed instructions");
34 STATISTIC(RelaxationSteps, "Number of assembler layout and relaxation steps");
35 STATISTIC(EmittedFragments, "Number of emitted assembler fragments");
36 STATISTIC(EvaluateFixup, "Number of evaluated fixups");
37 STATISTIC(ObjectBytes, "Number of emitted object file bytes");
41 // FIXME FIXME FIXME: There are number of places in this file where we convert
42 // what is a 64-bit assembler value used for computation into a value in the
43 // object file, which may truncate it. We should detect that truncation where
44 // invalid and report errors back.
48 void MCAsmLayout::UpdateForSlide(MCFragment *F, int SlideAmount) {
49 // We shouldn't have to do anything special to support negative slides, and it
50 // is a perfectly valid thing to do as long as other parts of the system are
51 // can guarantee convergence.
52 assert(SlideAmount >= 0 && "Negative slides not yet supported");
54 // Update the layout by simply recomputing the layout for the entire
55 // file. This is trivially correct, but very slow.
57 // FIXME-PERF: This is O(N^2), but will be eliminated once we get smarter.
59 // Layout the concrete sections and fragments.
60 MCAssembler &Asm = getAssembler();
62 for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it) {
63 // Skip virtual sections.
64 if (Asm.getBackend().isVirtualSection(it->getSection()))
67 // Layout the section fragments and its size.
68 Address = Asm.LayoutSection(*it, *this, Address);
71 // Layout the virtual sections.
72 for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it) {
73 if (!Asm.getBackend().isVirtualSection(it->getSection()))
76 // Layout the section fragments and its size.
77 Address = Asm.LayoutSection(*it, *this, Address);
81 uint64_t MCAsmLayout::getFragmentAddress(const MCFragment *F) const {
82 assert(F->getParent() && "Missing section()!");
83 return getSectionAddress(F->getParent()) + getFragmentOffset(F);
86 uint64_t MCAsmLayout::getFragmentEffectiveSize(const MCFragment *F) const {
87 assert(F->EffectiveSize != ~UINT64_C(0) && "Address not set!");
88 return F->EffectiveSize;
91 void MCAsmLayout::setFragmentEffectiveSize(MCFragment *F, uint64_t Value) {
92 F->EffectiveSize = Value;
95 uint64_t MCAsmLayout::getFragmentOffset(const MCFragment *F) const {
96 assert(F->Offset != ~UINT64_C(0) && "Address not set!");
100 void MCAsmLayout::setFragmentOffset(MCFragment *F, uint64_t Value) {
104 uint64_t MCAsmLayout::getSymbolAddress(const MCSymbolData *SD) const {
105 assert(SD->getFragment() && "Invalid getAddress() on undefined symbol!");
106 return getFragmentAddress(SD->getFragment()) + SD->getOffset();
109 uint64_t MCAsmLayout::getSectionAddress(const MCSectionData *SD) const {
110 assert(SD->Address != ~UINT64_C(0) && "Address not set!");
114 void MCAsmLayout::setSectionAddress(MCSectionData *SD, uint64_t Value) {
118 uint64_t MCAsmLayout::getSectionSize(const MCSectionData *SD) const {
119 assert(SD->Size != ~UINT64_C(0) && "File size not set!");
122 void MCAsmLayout::setSectionSize(MCSectionData *SD, uint64_t Value) {
126 uint64_t MCAsmLayout::getSectionFileSize(const MCSectionData *SD) const {
127 assert(SD->FileSize != ~UINT64_C(0) && "File size not set!");
130 void MCAsmLayout::setSectionFileSize(MCSectionData *SD, uint64_t Value) {
131 SD->FileSize = Value;
138 MCFragment::MCFragment() : Kind(FragmentType(~0)) {
141 MCFragment::MCFragment(FragmentType _Kind, MCSectionData *_Parent)
144 EffectiveSize(~UINT64_C(0))
147 Parent->getFragmentList().push_back(this);
150 MCFragment::~MCFragment() {
155 MCSectionData::MCSectionData() : Section(0) {}
157 MCSectionData::MCSectionData(const MCSection &_Section, MCAssembler *A)
158 : Section(&_Section),
160 Address(~UINT64_C(0)),
162 FileSize(~UINT64_C(0)),
163 HasInstructions(false)
166 A->getSectionList().push_back(this);
171 MCSymbolData::MCSymbolData() : Symbol(0) {}
173 MCSymbolData::MCSymbolData(const MCSymbol &_Symbol, MCFragment *_Fragment,
174 uint64_t _Offset, MCAssembler *A)
175 : Symbol(&_Symbol), Fragment(_Fragment), Offset(_Offset),
176 IsExternal(false), IsPrivateExtern(false),
177 CommonSize(0), CommonAlign(0), Flags(0), Index(0)
180 A->getSymbolList().push_back(this);
185 MCAssembler::MCAssembler(MCContext &_Context, TargetAsmBackend &_Backend,
186 MCCodeEmitter &_Emitter, raw_ostream &_OS)
187 : Context(_Context), Backend(_Backend), Emitter(_Emitter),
188 OS(_OS), SubsectionsViaSymbols(false)
192 MCAssembler::~MCAssembler() {
195 static bool isScatteredFixupFullyResolvedSimple(const MCAssembler &Asm,
196 const MCAsmFixup &Fixup,
197 const MCValue Target,
198 const MCSection *BaseSection) {
199 // The effective fixup address is
200 // addr(atom(A)) + offset(A)
201 // - addr(atom(B)) - offset(B)
202 // - addr(<base symbol>) + <fixup offset from base symbol>
203 // and the offsets are not relocatable, so the fixup is fully resolved when
204 // addr(atom(A)) - addr(atom(B)) - addr(<base symbol>)) == 0.
206 // The simple (Darwin, except on x86_64) way of dealing with this was to
207 // assume that any reference to a temporary symbol *must* be a temporary
208 // symbol in the same atom, unless the sections differ. Therefore, any PCrel
209 // relocation to a temporary symbol (in the same section) is fully
210 // resolved. This also works in conjunction with absolutized .set, which
211 // requires the compiler to use .set to absolutize the differences between
212 // symbols which the compiler knows to be assembly time constants, so we don't
213 // need to worry about consider symbol differences fully resolved.
215 // Non-relative fixups are only resolved if constant.
217 return Target.isAbsolute();
219 // Otherwise, relative fixups are only resolved if not a difference and the
220 // target is a temporary in the same section.
221 if (Target.isAbsolute() || Target.getSymB())
224 const MCSymbol *A = &Target.getSymA()->getSymbol();
225 if (!A->isTemporary() || !A->isInSection() ||
226 &A->getSection() != BaseSection)
232 static bool isScatteredFixupFullyResolved(const MCAssembler &Asm,
233 const MCAsmLayout &Layout,
234 const MCAsmFixup &Fixup,
235 const MCValue Target,
236 const MCSymbolData *BaseSymbol) {
237 // The effective fixup address is
238 // addr(atom(A)) + offset(A)
239 // - addr(atom(B)) - offset(B)
240 // - addr(BaseSymbol) + <fixup offset from base symbol>
241 // and the offsets are not relocatable, so the fixup is fully resolved when
242 // addr(atom(A)) - addr(atom(B)) - addr(BaseSymbol) == 0.
244 // Note that "false" is almost always conservatively correct (it means we emit
245 // a relocation which is unnecessary), except when it would force us to emit a
246 // relocation which the target cannot encode.
248 const MCSymbolData *A_Base = 0, *B_Base = 0;
249 if (const MCSymbolRefExpr *A = Target.getSymA()) {
250 // Modified symbol references cannot be resolved.
251 if (A->getKind() != MCSymbolRefExpr::VK_None)
254 A_Base = Asm.getAtom(Layout, &Asm.getSymbolData(A->getSymbol()));
259 if (const MCSymbolRefExpr *B = Target.getSymB()) {
260 // Modified symbol references cannot be resolved.
261 if (B->getKind() != MCSymbolRefExpr::VK_None)
264 B_Base = Asm.getAtom(Layout, &Asm.getSymbolData(B->getSymbol()));
269 // If there is no base, A and B have to be the same atom for this fixup to be
272 return A_Base == B_Base;
274 // Otherwise, B must be missing and A must be the base.
275 return !B_Base && BaseSymbol == A_Base;
278 bool MCAssembler::isSymbolLinkerVisible(const MCSymbolData *SD) const {
279 // Non-temporary labels should always be visible to the linker.
280 if (!SD->getSymbol().isTemporary())
283 // Absolute temporary labels are never visible.
284 if (!SD->getFragment())
287 // Otherwise, check if the section requires symbols even for temporary labels.
288 return getBackend().doesSectionRequireSymbols(
289 SD->getFragment()->getParent()->getSection());
292 // FIXME-PERF: This routine is really slow.
293 const MCSymbolData *MCAssembler::getAtomForAddress(const MCAsmLayout &Layout,
294 const MCSectionData *Section,
295 uint64_t Address) const {
296 const MCSymbolData *Best = 0;
297 uint64_t BestAddress = 0;
299 for (MCAssembler::const_symbol_iterator it = symbol_begin(),
300 ie = symbol_end(); it != ie; ++it) {
301 // Ignore non-linker visible symbols.
302 if (!isSymbolLinkerVisible(it))
305 // Ignore symbols not in the same section.
306 if (!it->getFragment() || it->getFragment()->getParent() != Section)
309 // Otherwise, find the closest symbol preceding this address (ties are
310 // resolved in favor of the last defined symbol).
311 uint64_t SymbolAddress = Layout.getSymbolAddress(it);
312 if (SymbolAddress <= Address && (!Best || SymbolAddress >= BestAddress)) {
314 BestAddress = SymbolAddress;
321 // FIXME-PERF: This routine is really slow.
322 const MCSymbolData *MCAssembler::getAtom(const MCAsmLayout &Layout,
323 const MCSymbolData *SD) const {
324 // Linker visible symbols define atoms.
325 if (isSymbolLinkerVisible(SD))
328 // Absolute and undefined symbols have no defining atom.
329 if (!SD->getFragment())
332 // Otherwise, search by address.
333 return getAtomForAddress(Layout, SD->getFragment()->getParent(),
334 Layout.getSymbolAddress(SD));
337 bool MCAssembler::EvaluateFixup(const MCAsmLayout &Layout,
338 const MCAsmFixup &Fixup, const MCFragment *DF,
339 MCValue &Target, uint64_t &Value) const {
340 ++stats::EvaluateFixup;
342 if (!Fixup.Value->EvaluateAsRelocatable(Target, &Layout))
343 llvm_report_error("expected relocatable expression");
345 // FIXME: How do non-scattered symbols work in ELF? I presume the linker
346 // doesn't support small relocations, but then under what criteria does the
347 // assembler allow symbol differences?
349 Value = Target.getConstant();
352 Emitter.getFixupKindInfo(Fixup.Kind).Flags & MCFixupKindInfo::FKF_IsPCRel;
353 bool IsResolved = true;
354 if (const MCSymbolRefExpr *A = Target.getSymA()) {
355 if (A->getSymbol().isDefined())
356 Value += Layout.getSymbolAddress(&getSymbolData(A->getSymbol()));
360 if (const MCSymbolRefExpr *B = Target.getSymB()) {
361 if (B->getSymbol().isDefined())
362 Value -= Layout.getSymbolAddress(&getSymbolData(B->getSymbol()));
367 // If we are using scattered symbols, determine whether this value is actually
368 // resolved; scattering may cause atoms to move.
369 if (IsResolved && getBackend().hasScatteredSymbols()) {
370 if (getBackend().hasReliableSymbolDifference()) {
371 // If this is a PCrel relocation, find the base atom (identified by its
372 // symbol) that the fixup value is relative to.
373 const MCSymbolData *BaseSymbol = 0;
375 BaseSymbol = getAtomForAddress(
376 Layout, DF->getParent(), Layout.getFragmentAddress(DF)+Fixup.Offset);
382 IsResolved = isScatteredFixupFullyResolved(*this, Layout, Fixup, Target,
385 const MCSection *BaseSection = 0;
387 BaseSection = &DF->getParent()->getSection();
389 IsResolved = isScatteredFixupFullyResolvedSimple(*this, Fixup, Target,
395 Value -= Layout.getFragmentAddress(DF) + Fixup.Offset;
400 uint64_t MCAssembler::LayoutSection(MCSectionData &SD,
402 uint64_t StartAddress) {
403 bool IsVirtual = getBackend().isVirtualSection(SD.getSection());
405 // Align this section if necessary by adding padding bytes to the previous
406 // section. It is safe to adjust this out-of-band, because no symbol or
407 // fragment is allowed to point past the end of the section at any time.
408 if (uint64_t Pad = OffsetToAlignment(StartAddress, SD.getAlignment())) {
409 // Unless this section is virtual (where we are allowed to adjust the offset
410 // freely), the padding goes in the previous section.
412 // Find the previous non-virtual section.
414 assert(it != begin() && "Invalid initial section address!");
415 for (--it; getBackend().isVirtualSection(it->getSection()); --it) ;
416 Layout.setSectionFileSize(&*it, Layout.getSectionFileSize(&*it) + Pad);
422 // Set the aligned section address.
423 Layout.setSectionAddress(&SD, StartAddress);
425 uint64_t Address = StartAddress;
426 for (MCSectionData::iterator it = SD.begin(), ie = SD.end(); it != ie; ++it) {
429 uint64_t FragmentOffset = Address - StartAddress;
430 Layout.setFragmentOffset(&F, FragmentOffset);
432 // Evaluate fragment size.
433 uint64_t EffectiveSize = 0;
434 switch (F.getKind()) {
435 case MCFragment::FT_Align: {
436 MCAlignFragment &AF = cast<MCAlignFragment>(F);
438 EffectiveSize = OffsetToAlignment(Address, AF.getAlignment());
439 if (EffectiveSize > AF.getMaxBytesToEmit())
444 case MCFragment::FT_Data:
445 EffectiveSize = cast<MCDataFragment>(F).getContents().size();
448 case MCFragment::FT_Fill: {
449 MCFillFragment &FF = cast<MCFillFragment>(F);
450 EffectiveSize = FF.getValueSize() * FF.getCount();
454 case MCFragment::FT_Inst:
455 EffectiveSize = cast<MCInstFragment>(F).getInstSize();
458 case MCFragment::FT_Org: {
459 MCOrgFragment &OF = cast<MCOrgFragment>(F);
461 int64_t TargetLocation;
462 if (!OF.getOffset().EvaluateAsAbsolute(TargetLocation, &Layout))
463 llvm_report_error("expected assembly-time absolute expression");
465 // FIXME: We need a way to communicate this error.
466 int64_t Offset = TargetLocation - FragmentOffset;
468 llvm_report_error("invalid .org offset '" + Twine(TargetLocation) +
469 "' (at offset '" + Twine(FragmentOffset) + "'");
471 EffectiveSize = Offset;
475 case MCFragment::FT_ZeroFill: {
476 MCZeroFillFragment &ZFF = cast<MCZeroFillFragment>(F);
478 // Align the fragment offset; it is safe to adjust the offset freely since
479 // this is only in virtual sections.
481 // FIXME: We shouldn't be doing this here.
482 Address = RoundUpToAlignment(Address, ZFF.getAlignment());
483 Layout.setFragmentOffset(&F, Address - StartAddress);
485 EffectiveSize = ZFF.getSize();
490 Layout.setFragmentEffectiveSize(&F, EffectiveSize);
491 Address += EffectiveSize;
494 // Set the section sizes.
495 Layout.setSectionSize(&SD, Address - StartAddress);
497 Layout.setSectionFileSize(&SD, 0);
499 Layout.setSectionFileSize(&SD, Address - StartAddress);
504 /// WriteFragmentData - Write the \arg F data to the output file.
505 static void WriteFragmentData(const MCAssembler &Asm, const MCAsmLayout &Layout,
506 const MCFragment &F, MCObjectWriter *OW) {
507 uint64_t Start = OW->getStream().tell();
510 ++stats::EmittedFragments;
512 // FIXME: Embed in fragments instead?
513 uint64_t FragmentSize = Layout.getFragmentEffectiveSize(&F);
514 switch (F.getKind()) {
515 case MCFragment::FT_Align: {
516 MCAlignFragment &AF = cast<MCAlignFragment>(F);
517 uint64_t Count = FragmentSize / AF.getValueSize();
519 // FIXME: This error shouldn't actually occur (the front end should emit
520 // multiple .align directives to enforce the semantics it wants), but is
521 // severe enough that we want to report it. How to handle this?
522 if (Count * AF.getValueSize() != FragmentSize)
523 llvm_report_error("undefined .align directive, value size '" +
524 Twine(AF.getValueSize()) +
525 "' is not a divisor of padding size '" +
526 Twine(FragmentSize) + "'");
528 // See if we are aligning with nops, and if so do that first to try to fill
529 // the Count bytes. Then if that did not fill any bytes or there are any
530 // bytes left to fill use the the Value and ValueSize to fill the rest.
531 // If we are aligning with nops, ask that target to emit the right data.
532 if (AF.getEmitNops()) {
533 if (!Asm.getBackend().WriteNopData(Count, OW))
534 llvm_report_error("unable to write nop sequence of " +
535 Twine(Count) + " bytes");
539 // Otherwise, write out in multiples of the value size.
540 for (uint64_t i = 0; i != Count; ++i) {
541 switch (AF.getValueSize()) {
543 assert(0 && "Invalid size!");
544 case 1: OW->Write8 (uint8_t (AF.getValue())); break;
545 case 2: OW->Write16(uint16_t(AF.getValue())); break;
546 case 4: OW->Write32(uint32_t(AF.getValue())); break;
547 case 8: OW->Write64(uint64_t(AF.getValue())); break;
553 case MCFragment::FT_Data: {
554 MCDataFragment &DF = cast<MCDataFragment>(F);
555 assert(FragmentSize == DF.getContents().size() && "Invalid size!");
556 OW->WriteBytes(DF.getContents().str());
560 case MCFragment::FT_Fill: {
561 MCFillFragment &FF = cast<MCFillFragment>(F);
562 for (uint64_t i = 0, e = FF.getCount(); i != e; ++i) {
563 switch (FF.getValueSize()) {
565 assert(0 && "Invalid size!");
566 case 1: OW->Write8 (uint8_t (FF.getValue())); break;
567 case 2: OW->Write16(uint16_t(FF.getValue())); break;
568 case 4: OW->Write32(uint32_t(FF.getValue())); break;
569 case 8: OW->Write64(uint64_t(FF.getValue())); break;
575 case MCFragment::FT_Inst:
576 llvm_unreachable("unexpected inst fragment after lowering");
579 case MCFragment::FT_Org: {
580 MCOrgFragment &OF = cast<MCOrgFragment>(F);
582 for (uint64_t i = 0, e = FragmentSize; i != e; ++i)
583 OW->Write8(uint8_t(OF.getValue()));
588 case MCFragment::FT_ZeroFill: {
589 assert(0 && "Invalid zero fill fragment in concrete section!");
594 assert(OW->getStream().tell() - Start == FragmentSize);
597 void MCAssembler::WriteSectionData(const MCSectionData *SD,
598 const MCAsmLayout &Layout,
599 MCObjectWriter *OW) const {
600 uint64_t SectionSize = Layout.getSectionSize(SD);
601 uint64_t SectionFileSize = Layout.getSectionFileSize(SD);
603 // Ignore virtual sections.
604 if (getBackend().isVirtualSection(SD->getSection())) {
605 assert(SectionFileSize == 0 && "Invalid size for section!");
609 uint64_t Start = OW->getStream().tell();
612 for (MCSectionData::const_iterator it = SD->begin(),
613 ie = SD->end(); it != ie; ++it)
614 WriteFragmentData(*this, Layout, *it, OW);
616 // Add section padding.
617 assert(SectionFileSize >= SectionSize && "Invalid section sizes!");
618 OW->WriteZeros(SectionFileSize - SectionSize);
620 assert(OW->getStream().tell() - Start == SectionFileSize);
623 void MCAssembler::Finish() {
624 DEBUG_WITH_TYPE("mc-dump", {
625 llvm::errs() << "assembler backend - pre-layout\n--\n";
628 // Assign section and fragment ordinals, all subsequent backend code is
629 // responsible for updating these in place.
630 unsigned SectionIndex = 0;
631 unsigned FragmentIndex = 0;
632 for (MCAssembler::iterator it = begin(), ie = end(); it != ie; ++it) {
633 it->setOrdinal(SectionIndex++);
635 for (MCSectionData::iterator it2 = it->begin(),
636 ie2 = it->end(); it2 != ie2; ++it2)
637 it2->setOrdinal(FragmentIndex++);
640 // Layout until everything fits.
641 MCAsmLayout Layout(*this);
642 while (LayoutOnce(Layout))
645 DEBUG_WITH_TYPE("mc-dump", {
646 llvm::errs() << "assembler backend - post-relaxation\n--\n";
649 // Finalize the layout, including fragment lowering.
650 FinishLayout(Layout);
652 DEBUG_WITH_TYPE("mc-dump", {
653 llvm::errs() << "assembler backend - final-layout\n--\n";
656 uint64_t StartOffset = OS.tell();
657 llvm::OwningPtr<MCObjectWriter> Writer(getBackend().createObjectWriter(OS));
659 llvm_report_error("unable to create object writer!");
661 // Allow the object writer a chance to perform post-layout binding (for
662 // example, to set the index fields in the symbol data).
663 Writer->ExecutePostLayoutBinding(*this);
665 // Evaluate and apply the fixups, generating relocation entries as necessary.
666 for (MCAssembler::iterator it = begin(), ie = end(); it != ie; ++it) {
667 for (MCSectionData::iterator it2 = it->begin(),
668 ie2 = it->end(); it2 != ie2; ++it2) {
669 MCDataFragment *DF = dyn_cast<MCDataFragment>(it2);
673 for (MCDataFragment::fixup_iterator it3 = DF->fixup_begin(),
674 ie3 = DF->fixup_end(); it3 != ie3; ++it3) {
675 MCAsmFixup &Fixup = *it3;
677 // Evaluate the fixup.
680 if (!EvaluateFixup(Layout, Fixup, DF, Target, FixedValue)) {
681 // The fixup was unresolved, we need a relocation. Inform the object
682 // writer of the relocation, and give it an opportunity to adjust the
683 // fixup value if need be.
684 Writer->RecordRelocation(*this, Layout, DF, Fixup, Target,FixedValue);
687 getBackend().ApplyFixup(Fixup, *DF, FixedValue);
692 // Write the object file.
693 Writer->WriteObject(*this, Layout);
696 stats::ObjectBytes += OS.tell() - StartOffset;
699 bool MCAssembler::FixupNeedsRelaxation(const MCAsmFixup &Fixup,
700 const MCFragment *DF,
701 const MCAsmLayout &Layout) const {
702 // If we cannot resolve the fixup value, it requires relaxation.
705 if (!EvaluateFixup(Layout, Fixup, DF, Target, Value))
708 // Otherwise, relax if the value is too big for a (signed) i8.
709 return int64_t(Value) != int64_t(int8_t(Value));
712 bool MCAssembler::FragmentNeedsRelaxation(const MCInstFragment *IF,
713 const MCAsmLayout &Layout) const {
714 // If this inst doesn't ever need relaxation, ignore it. This occurs when we
715 // are intentionally pushing out inst fragments, or because we relaxed a
716 // previous instruction to one that doesn't need relaxation.
717 if (!getBackend().MayNeedRelaxation(IF->getInst(), IF->getFixups()))
720 for (MCInstFragment::const_fixup_iterator it = IF->fixup_begin(),
721 ie = IF->fixup_end(); it != ie; ++it)
722 if (FixupNeedsRelaxation(*it, IF, Layout))
728 bool MCAssembler::LayoutOnce(MCAsmLayout &Layout) {
729 ++stats::RelaxationSteps;
731 // Layout the concrete sections and fragments.
732 uint64_t Address = 0;
733 for (iterator it = begin(), ie = end(); it != ie; ++it) {
734 // Skip virtual sections.
735 if (getBackend().isVirtualSection(it->getSection()))
738 // Layout the section fragments and its size.
739 Address = LayoutSection(*it, Layout, Address);
742 // Layout the virtual sections.
743 for (iterator it = begin(), ie = end(); it != ie; ++it) {
744 if (!getBackend().isVirtualSection(it->getSection()))
747 // Layout the section fragments and its size.
748 Address = LayoutSection(*it, Layout, Address);
751 // Scan for fragments that need relaxation.
752 bool WasRelaxed = false;
753 for (iterator it = begin(), ie = end(); it != ie; ++it) {
754 MCSectionData &SD = *it;
756 for (MCSectionData::iterator it2 = SD.begin(),
757 ie2 = SD.end(); it2 != ie2; ++it2) {
758 // Check if this is an instruction fragment that needs relaxation.
759 MCInstFragment *IF = dyn_cast<MCInstFragment>(it2);
760 if (!IF || !FragmentNeedsRelaxation(IF, Layout))
763 ++stats::RelaxedInstructions;
765 // FIXME-PERF: We could immediately lower out instructions if we can tell
766 // they are fully resolved, to avoid retesting on later passes.
768 // Relax the fragment.
771 getBackend().RelaxInstruction(IF, Relaxed);
773 // Encode the new instruction.
775 // FIXME-PERF: If it matters, we could let the target do this. It can
776 // probably do so more efficiently in many cases.
777 SmallVector<MCFixup, 4> Fixups;
778 SmallString<256> Code;
779 raw_svector_ostream VecOS(Code);
780 getEmitter().EncodeInstruction(Relaxed, VecOS, Fixups);
783 // Update the instruction fragment.
784 int SlideAmount = Code.size() - IF->getInstSize();
785 IF->setInst(Relaxed);
786 IF->getCode() = Code;
787 IF->getFixups().clear();
788 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
789 MCFixup &F = Fixups[i];
790 IF->getFixups().push_back(MCAsmFixup(F.getOffset(), *F.getValue(),
794 // Update the layout, and remember that we relaxed.
795 Layout.UpdateForSlide(IF, SlideAmount);
803 void MCAssembler::FinishLayout(MCAsmLayout &Layout) {
804 // Lower out any instruction fragments, to simplify the fixup application and
807 // FIXME-PERF: We don't have to do this, but the assumption is that it is
808 // cheap (we will mostly end up eliminating fragments and appending on to data
809 // fragments), so the extra complexity downstream isn't worth it. Evaluate
811 for (iterator it = begin(), ie = end(); it != ie; ++it) {
812 MCSectionData &SD = *it;
814 for (MCSectionData::iterator it2 = SD.begin(),
815 ie2 = SD.end(); it2 != ie2; ++it2) {
816 MCInstFragment *IF = dyn_cast<MCInstFragment>(it2);
820 // Create a new data fragment for the instruction.
822 // FIXME-PERF: Reuse previous data fragment if possible.
823 MCDataFragment *DF = new MCDataFragment();
824 SD.getFragmentList().insert(it2, DF);
826 // Update the data fragments layout data.
828 // FIXME: Add MCAsmLayout utility for this.
829 DF->setParent(IF->getParent());
830 DF->setOrdinal(IF->getOrdinal());
831 Layout.setFragmentOffset(DF, Layout.getFragmentOffset(IF));
832 Layout.setFragmentEffectiveSize(DF, Layout.getFragmentEffectiveSize(IF));
834 // Copy in the data and the fixups.
835 DF->getContents().append(IF->getCode().begin(), IF->getCode().end());
836 for (unsigned i = 0, e = IF->getFixups().size(); i != e; ++i)
837 DF->getFixups().push_back(IF->getFixups()[i]);
839 // Delete the instruction fragment and update the iterator.
840 SD.getFragmentList().erase(IF);
850 raw_ostream &operator<<(raw_ostream &OS, const MCAsmFixup &AF) {
851 OS << "<MCAsmFixup" << " Offset:" << AF.Offset << " Value:" << *AF.Value
852 << " Kind:" << AF.Kind << ">";
858 void MCFragment::dump() {
859 raw_ostream &OS = llvm::errs();
861 OS << "<MCFragment " << (void*) this << " Offset:" << Offset
862 << " EffectiveSize:" << EffectiveSize;
867 void MCAlignFragment::dump() {
868 raw_ostream &OS = llvm::errs();
870 OS << "<MCAlignFragment ";
871 this->MCFragment::dump();
873 OS << " Alignment:" << getAlignment()
874 << " Value:" << getValue() << " ValueSize:" << getValueSize()
875 << " MaxBytesToEmit:" << getMaxBytesToEmit() << ">";
878 void MCDataFragment::dump() {
879 raw_ostream &OS = llvm::errs();
881 OS << "<MCDataFragment ";
882 this->MCFragment::dump();
885 for (unsigned i = 0, e = getContents().size(); i != e; ++i) {
887 OS << hexdigit((Contents[i] >> 4) & 0xF) << hexdigit(Contents[i] & 0xF);
889 OS << "] (" << getContents().size() << " bytes)";
891 if (!getFixups().empty()) {
894 for (fixup_iterator it = fixup_begin(), ie = fixup_end(); it != ie; ++it) {
895 if (it != fixup_begin()) OS << ",\n ";
904 void MCFillFragment::dump() {
905 raw_ostream &OS = llvm::errs();
907 OS << "<MCFillFragment ";
908 this->MCFragment::dump();
910 OS << " Value:" << getValue() << " ValueSize:" << getValueSize()
911 << " Count:" << getCount() << ">";
914 void MCInstFragment::dump() {
915 raw_ostream &OS = llvm::errs();
917 OS << "<MCInstFragment ";
918 this->MCFragment::dump();
921 getInst().dump_pretty(OS);
925 void MCOrgFragment::dump() {
926 raw_ostream &OS = llvm::errs();
928 OS << "<MCOrgFragment ";
929 this->MCFragment::dump();
931 OS << " Offset:" << getOffset() << " Value:" << getValue() << ">";
934 void MCZeroFillFragment::dump() {
935 raw_ostream &OS = llvm::errs();
937 OS << "<MCZeroFillFragment ";
938 this->MCFragment::dump();
940 OS << " Size:" << getSize() << " Alignment:" << getAlignment() << ">";
943 void MCSectionData::dump() {
944 raw_ostream &OS = llvm::errs();
946 OS << "<MCSectionData";
947 OS << " Alignment:" << getAlignment() << " Address:" << Address
948 << " Size:" << Size << " FileSize:" << FileSize
949 << " Fragments:[\n ";
950 for (iterator it = begin(), ie = end(); it != ie; ++it) {
951 if (it != begin()) OS << ",\n ";
957 void MCSymbolData::dump() {
958 raw_ostream &OS = llvm::errs();
960 OS << "<MCSymbolData Symbol:" << getSymbol()
961 << " Fragment:" << getFragment() << " Offset:" << getOffset()
962 << " Flags:" << getFlags() << " Index:" << getIndex();
964 OS << " (common, size:" << getCommonSize()
965 << " align: " << getCommonAlignment() << ")";
968 if (isPrivateExtern())
969 OS << " (private extern)";
973 void MCAssembler::dump() {
974 raw_ostream &OS = llvm::errs();
976 OS << "<MCAssembler\n";
977 OS << " Sections:[\n ";
978 for (iterator it = begin(), ie = end(); it != ie; ++it) {
979 if (it != begin()) OS << ",\n ";
985 for (symbol_iterator it = symbol_begin(), ie = symbol_end(); it != ie; ++it) {
986 if (it != symbol_begin()) OS << ",\n ";