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/Debug.h"
23 #include "llvm/Support/ErrorHandling.h"
24 #include "llvm/Support/raw_ostream.h"
25 #include "llvm/Target/TargetRegistry.h"
26 #include "llvm/Target/TargetAsmBackend.h"
33 STATISTIC(EmittedFragments, "Number of emitted assembler fragments");
34 STATISTIC(EvaluateFixup, "Number of evaluated fixups");
35 STATISTIC(FragmentLayouts, "Number of fragment layouts");
36 STATISTIC(ObjectBytes, "Number of emitted object file bytes");
37 STATISTIC(RelaxationSteps, "Number of assembler layout and relaxation steps");
38 STATISTIC(RelaxedInstructions, "Number of relaxed instructions");
39 STATISTIC(SectionLayouts, "Number of section layouts");
43 // FIXME FIXME FIXME: There are number of places in this file where we convert
44 // what is a 64-bit assembler value used for computation into a value in the
45 // object file, which may truncate it. We should detect that truncation where
46 // invalid and report errors back.
50 MCAsmLayout::MCAsmLayout(MCAssembler &Asm) : Assembler(Asm) {
51 // Compute the section layout order. Virtual sections must go last.
52 for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it)
53 if (!Asm.getBackend().isVirtualSection(it->getSection()))
54 SectionOrder.push_back(&*it);
55 for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it)
56 if (Asm.getBackend().isVirtualSection(it->getSection()))
57 SectionOrder.push_back(&*it);
60 void MCAsmLayout::UpdateForSlide(MCFragment *F, int SlideAmount) {
61 // We shouldn't have to do anything special to support negative slides, and it
62 // is a perfectly valid thing to do as long as other parts of the system can
63 // guarantee convergence.
64 assert(SlideAmount >= 0 && "Negative slides not yet supported");
66 // Update the layout by simply recomputing the layout for the entire
67 // file. This is trivially correct, but very slow.
69 // FIXME-PERF: This is O(N^2), but will be eliminated once we get smarter.
71 // Layout the concrete sections and fragments.
73 for (iterator it = begin(), ie = end(); it != ie; ++it) {
74 // Layout the section fragments and its size.
75 Address = getAssembler().LayoutSection(**it, *this, Address);
79 uint64_t MCAsmLayout::getFragmentAddress(const MCFragment *F) const {
80 assert(F->getParent() && "Missing section()!");
81 return getSectionAddress(F->getParent()) + getFragmentOffset(F);
84 uint64_t MCAsmLayout::getFragmentEffectiveSize(const MCFragment *F) const {
85 assert(F->EffectiveSize != ~UINT64_C(0) && "Address not set!");
86 return F->EffectiveSize;
89 void MCAsmLayout::setFragmentEffectiveSize(MCFragment *F, uint64_t Value) {
90 F->EffectiveSize = Value;
93 uint64_t MCAsmLayout::getFragmentOffset(const MCFragment *F) const {
94 assert(F->Offset != ~UINT64_C(0) && "Address not set!");
98 void MCAsmLayout::setFragmentOffset(MCFragment *F, uint64_t Value) {
102 uint64_t MCAsmLayout::getSymbolAddress(const MCSymbolData *SD) const {
103 assert(SD->getFragment() && "Invalid getAddress() on undefined symbol!");
104 return getFragmentAddress(SD->getFragment()) + SD->getOffset();
107 uint64_t MCAsmLayout::getSectionAddress(const MCSectionData *SD) const {
108 assert(SD->Address != ~UINT64_C(0) && "Address not set!");
112 void MCAsmLayout::setSectionAddress(MCSectionData *SD, uint64_t Value) {
116 uint64_t MCAsmLayout::getSectionSize(const MCSectionData *SD) const {
117 assert(SD->Size != ~UINT64_C(0) && "File size not set!");
120 void MCAsmLayout::setSectionSize(MCSectionData *SD, uint64_t Value) {
124 uint64_t MCAsmLayout::getSectionFileSize(const MCSectionData *SD) const {
125 assert(SD->FileSize != ~UINT64_C(0) && "File size not set!");
128 void MCAsmLayout::setSectionFileSize(MCSectionData *SD, uint64_t Value) {
129 SD->FileSize = Value;
134 MCFragment::MCFragment() : Kind(FragmentType(~0)) {
137 MCFragment::MCFragment(FragmentType _Kind, MCSectionData *_Parent)
138 : Kind(_Kind), Parent(_Parent), Atom(0), EffectiveSize(~UINT64_C(0))
141 Parent->getFragmentList().push_back(this);
144 MCFragment::~MCFragment() {
149 MCSectionData::MCSectionData() : Section(0) {}
151 MCSectionData::MCSectionData(const MCSection &_Section, MCAssembler *A)
152 : Section(&_Section),
154 Address(~UINT64_C(0)),
156 FileSize(~UINT64_C(0)),
157 HasInstructions(false)
160 A->getSectionList().push_back(this);
165 MCSymbolData::MCSymbolData() : Symbol(0) {}
167 MCSymbolData::MCSymbolData(const MCSymbol &_Symbol, MCFragment *_Fragment,
168 uint64_t _Offset, MCAssembler *A)
169 : Symbol(&_Symbol), Fragment(_Fragment), Offset(_Offset),
170 IsExternal(false), IsPrivateExtern(false),
171 CommonSize(0), CommonAlign(0), Flags(0), Index(0)
174 A->getSymbolList().push_back(this);
179 MCAssembler::MCAssembler(MCContext &_Context, TargetAsmBackend &_Backend,
180 MCCodeEmitter &_Emitter, raw_ostream &_OS)
181 : Context(_Context), Backend(_Backend), Emitter(_Emitter),
182 OS(_OS), RelaxAll(false), SubsectionsViaSymbols(false)
186 MCAssembler::~MCAssembler() {
189 static bool isScatteredFixupFullyResolvedSimple(const MCAssembler &Asm,
190 const MCAsmFixup &Fixup,
191 const MCValue Target,
192 const MCSection *BaseSection) {
193 // The effective fixup address is
194 // addr(atom(A)) + offset(A)
195 // - addr(atom(B)) - offset(B)
196 // - addr(<base symbol>) + <fixup offset from base symbol>
197 // and the offsets are not relocatable, so the fixup is fully resolved when
198 // addr(atom(A)) - addr(atom(B)) - addr(<base symbol>)) == 0.
200 // The simple (Darwin, except on x86_64) way of dealing with this was to
201 // assume that any reference to a temporary symbol *must* be a temporary
202 // symbol in the same atom, unless the sections differ. Therefore, any PCrel
203 // relocation to a temporary symbol (in the same section) is fully
204 // resolved. This also works in conjunction with absolutized .set, which
205 // requires the compiler to use .set to absolutize the differences between
206 // symbols which the compiler knows to be assembly time constants, so we don't
207 // need to worry about considering symbol differences fully resolved.
209 // Non-relative fixups are only resolved if constant.
211 return Target.isAbsolute();
213 // Otherwise, relative fixups are only resolved if not a difference and the
214 // target is a temporary in the same section.
215 if (Target.isAbsolute() || Target.getSymB())
218 const MCSymbol *A = &Target.getSymA()->getSymbol();
219 if (!A->isTemporary() || !A->isInSection() ||
220 &A->getSection() != BaseSection)
226 static bool isScatteredFixupFullyResolved(const MCAssembler &Asm,
227 const MCAsmLayout &Layout,
228 const MCAsmFixup &Fixup,
229 const MCValue Target,
230 const MCSymbolData *BaseSymbol) {
231 // The effective fixup address is
232 // addr(atom(A)) + offset(A)
233 // - addr(atom(B)) - offset(B)
234 // - addr(BaseSymbol) + <fixup offset from base symbol>
235 // and the offsets are not relocatable, so the fixup is fully resolved when
236 // addr(atom(A)) - addr(atom(B)) - addr(BaseSymbol) == 0.
238 // Note that "false" is almost always conservatively correct (it means we emit
239 // a relocation which is unnecessary), except when it would force us to emit a
240 // relocation which the target cannot encode.
242 const MCSymbolData *A_Base = 0, *B_Base = 0;
243 if (const MCSymbolRefExpr *A = Target.getSymA()) {
244 // Modified symbol references cannot be resolved.
245 if (A->getKind() != MCSymbolRefExpr::VK_None)
248 A_Base = Asm.getAtom(Layout, &Asm.getSymbolData(A->getSymbol()));
253 if (const MCSymbolRefExpr *B = Target.getSymB()) {
254 // Modified symbol references cannot be resolved.
255 if (B->getKind() != MCSymbolRefExpr::VK_None)
258 B_Base = Asm.getAtom(Layout, &Asm.getSymbolData(B->getSymbol()));
263 // If there is no base, A and B have to be the same atom for this fixup to be
266 return A_Base == B_Base;
268 // Otherwise, B must be missing and A must be the base.
269 return !B_Base && BaseSymbol == A_Base;
272 bool MCAssembler::isSymbolLinkerVisible(const MCSymbolData *SD) const {
273 // Non-temporary labels should always be visible to the linker.
274 if (!SD->getSymbol().isTemporary())
277 // Absolute temporary labels are never visible.
278 if (!SD->getFragment())
281 // Otherwise, check if the section requires symbols even for temporary labels.
282 return getBackend().doesSectionRequireSymbols(
283 SD->getFragment()->getParent()->getSection());
286 const MCSymbolData *MCAssembler::getAtom(const MCAsmLayout &Layout,
287 const MCSymbolData *SD) const {
288 // Linker visible symbols define atoms.
289 if (isSymbolLinkerVisible(SD))
292 // Absolute and undefined symbols have no defining atom.
293 if (!SD->getFragment())
296 // Non-linker visible symbols in sections which can't be atomized have no
298 if (!getBackend().isSectionAtomizable(
299 SD->getFragment()->getParent()->getSection()))
302 // Otherwise, return the atom for the containing fragment.
303 return SD->getFragment()->getAtom();
306 bool MCAssembler::EvaluateFixup(const MCAsmLayout &Layout,
307 const MCAsmFixup &Fixup, const MCFragment *DF,
308 MCValue &Target, uint64_t &Value) const {
309 ++stats::EvaluateFixup;
311 if (!Fixup.Value->EvaluateAsRelocatable(Target, &Layout))
312 report_fatal_error("expected relocatable expression");
314 // FIXME: How do non-scattered symbols work in ELF? I presume the linker
315 // doesn't support small relocations, but then under what criteria does the
316 // assembler allow symbol differences?
318 Value = Target.getConstant();
321 Emitter.getFixupKindInfo(Fixup.Kind).Flags & MCFixupKindInfo::FKF_IsPCRel;
322 bool IsResolved = true;
323 if (const MCSymbolRefExpr *A = Target.getSymA()) {
324 if (A->getSymbol().isDefined())
325 Value += Layout.getSymbolAddress(&getSymbolData(A->getSymbol()));
329 if (const MCSymbolRefExpr *B = Target.getSymB()) {
330 if (B->getSymbol().isDefined())
331 Value -= Layout.getSymbolAddress(&getSymbolData(B->getSymbol()));
336 // If we are using scattered symbols, determine whether this value is actually
337 // resolved; scattering may cause atoms to move.
338 if (IsResolved && getBackend().hasScatteredSymbols()) {
339 if (getBackend().hasReliableSymbolDifference()) {
340 // If this is a PCrel relocation, find the base atom (identified by its
341 // symbol) that the fixup value is relative to.
342 const MCSymbolData *BaseSymbol = 0;
344 BaseSymbol = DF->getAtom();
350 IsResolved = isScatteredFixupFullyResolved(*this, Layout, Fixup, Target,
353 const MCSection *BaseSection = 0;
355 BaseSection = &DF->getParent()->getSection();
357 IsResolved = isScatteredFixupFullyResolvedSimple(*this, Fixup, Target,
363 Value -= Layout.getFragmentAddress(DF) + Fixup.Offset;
368 uint64_t MCAssembler::LayoutSection(MCSectionData &SD,
370 uint64_t StartAddress) {
371 bool IsVirtual = getBackend().isVirtualSection(SD.getSection());
373 ++stats::SectionLayouts;
375 // Align this section if necessary by adding padding bytes to the previous
376 // section. It is safe to adjust this out-of-band, because no symbol or
377 // fragment is allowed to point past the end of the section at any time.
378 if (uint64_t Pad = OffsetToAlignment(StartAddress, SD.getAlignment())) {
379 // Unless this section is virtual (where we are allowed to adjust the offset
380 // freely), the padding goes in the previous section.
382 // Find the previous non-virtual section.
384 assert(it != begin() && "Invalid initial section address!");
385 for (--it; getBackend().isVirtualSection(it->getSection()); --it) ;
386 Layout.setSectionFileSize(&*it, Layout.getSectionFileSize(&*it) + Pad);
392 // Set the aligned section address.
393 Layout.setSectionAddress(&SD, StartAddress);
395 uint64_t Address = StartAddress;
396 for (MCSectionData::iterator it = SD.begin(), ie = SD.end(); it != ie; ++it) {
399 ++stats::FragmentLayouts;
401 uint64_t FragmentOffset = Address - StartAddress;
402 Layout.setFragmentOffset(&F, FragmentOffset);
404 // Evaluate fragment size.
405 uint64_t EffectiveSize = 0;
406 switch (F.getKind()) {
407 case MCFragment::FT_Align: {
408 MCAlignFragment &AF = cast<MCAlignFragment>(F);
410 EffectiveSize = OffsetToAlignment(Address, AF.getAlignment());
411 if (EffectiveSize > AF.getMaxBytesToEmit())
416 case MCFragment::FT_Data:
417 EffectiveSize = cast<MCDataFragment>(F).getContents().size();
420 case MCFragment::FT_Fill: {
421 MCFillFragment &FF = cast<MCFillFragment>(F);
422 EffectiveSize = FF.getValueSize() * FF.getCount();
426 case MCFragment::FT_Inst:
427 EffectiveSize = cast<MCInstFragment>(F).getInstSize();
430 case MCFragment::FT_Org: {
431 MCOrgFragment &OF = cast<MCOrgFragment>(F);
433 int64_t TargetLocation;
434 if (!OF.getOffset().EvaluateAsAbsolute(TargetLocation, &Layout))
435 report_fatal_error("expected assembly-time absolute expression");
437 // FIXME: We need a way to communicate this error.
438 int64_t Offset = TargetLocation - FragmentOffset;
440 report_fatal_error("invalid .org offset '" + Twine(TargetLocation) +
441 "' (at offset '" + Twine(FragmentOffset) + "'");
443 EffectiveSize = Offset;
447 case MCFragment::FT_ZeroFill: {
448 MCZeroFillFragment &ZFF = cast<MCZeroFillFragment>(F);
450 // Align the fragment offset; it is safe to adjust the offset freely since
451 // this is only in virtual sections.
453 // FIXME: We shouldn't be doing this here.
454 Address = RoundUpToAlignment(Address, ZFF.getAlignment());
455 Layout.setFragmentOffset(&F, Address - StartAddress);
457 EffectiveSize = ZFF.getSize();
462 Layout.setFragmentEffectiveSize(&F, EffectiveSize);
463 Address += EffectiveSize;
466 // Set the section sizes.
467 Layout.setSectionSize(&SD, Address - StartAddress);
469 Layout.setSectionFileSize(&SD, 0);
471 Layout.setSectionFileSize(&SD, Address - StartAddress);
476 /// WriteFragmentData - Write the \arg F data to the output file.
477 static void WriteFragmentData(const MCAssembler &Asm, const MCAsmLayout &Layout,
478 const MCFragment &F, MCObjectWriter *OW) {
479 uint64_t Start = OW->getStream().tell();
482 ++stats::EmittedFragments;
484 // FIXME: Embed in fragments instead?
485 uint64_t FragmentSize = Layout.getFragmentEffectiveSize(&F);
486 switch (F.getKind()) {
487 case MCFragment::FT_Align: {
488 MCAlignFragment &AF = cast<MCAlignFragment>(F);
489 uint64_t Count = FragmentSize / AF.getValueSize();
491 // FIXME: This error shouldn't actually occur (the front end should emit
492 // multiple .align directives to enforce the semantics it wants), but is
493 // severe enough that we want to report it. How to handle this?
494 if (Count * AF.getValueSize() != FragmentSize)
495 report_fatal_error("undefined .align directive, value size '" +
496 Twine(AF.getValueSize()) +
497 "' is not a divisor of padding size '" +
498 Twine(FragmentSize) + "'");
500 // See if we are aligning with nops, and if so do that first to try to fill
501 // the Count bytes. Then if that did not fill any bytes or there are any
502 // bytes left to fill use the the Value and ValueSize to fill the rest.
503 // If we are aligning with nops, ask that target to emit the right data.
504 if (AF.getEmitNops()) {
505 if (!Asm.getBackend().WriteNopData(Count, OW))
506 report_fatal_error("unable to write nop sequence of " +
507 Twine(Count) + " bytes");
511 // Otherwise, write out in multiples of the value size.
512 for (uint64_t i = 0; i != Count; ++i) {
513 switch (AF.getValueSize()) {
515 assert(0 && "Invalid size!");
516 case 1: OW->Write8 (uint8_t (AF.getValue())); break;
517 case 2: OW->Write16(uint16_t(AF.getValue())); break;
518 case 4: OW->Write32(uint32_t(AF.getValue())); break;
519 case 8: OW->Write64(uint64_t(AF.getValue())); break;
525 case MCFragment::FT_Data: {
526 MCDataFragment &DF = cast<MCDataFragment>(F);
527 assert(FragmentSize == DF.getContents().size() && "Invalid size!");
528 OW->WriteBytes(DF.getContents().str());
532 case MCFragment::FT_Fill: {
533 MCFillFragment &FF = cast<MCFillFragment>(F);
534 for (uint64_t i = 0, e = FF.getCount(); i != e; ++i) {
535 switch (FF.getValueSize()) {
537 assert(0 && "Invalid size!");
538 case 1: OW->Write8 (uint8_t (FF.getValue())); break;
539 case 2: OW->Write16(uint16_t(FF.getValue())); break;
540 case 4: OW->Write32(uint32_t(FF.getValue())); break;
541 case 8: OW->Write64(uint64_t(FF.getValue())); break;
547 case MCFragment::FT_Inst:
548 llvm_unreachable("unexpected inst fragment after lowering");
551 case MCFragment::FT_Org: {
552 MCOrgFragment &OF = cast<MCOrgFragment>(F);
554 for (uint64_t i = 0, e = FragmentSize; i != e; ++i)
555 OW->Write8(uint8_t(OF.getValue()));
560 case MCFragment::FT_ZeroFill: {
561 assert(0 && "Invalid zero fill fragment in concrete section!");
566 assert(OW->getStream().tell() - Start == FragmentSize);
569 void MCAssembler::WriteSectionData(const MCSectionData *SD,
570 const MCAsmLayout &Layout,
571 MCObjectWriter *OW) const {
572 uint64_t SectionSize = Layout.getSectionSize(SD);
573 uint64_t SectionFileSize = Layout.getSectionFileSize(SD);
575 // Ignore virtual sections.
576 if (getBackend().isVirtualSection(SD->getSection())) {
577 assert(SectionFileSize == 0 && "Invalid size for section!");
581 uint64_t Start = OW->getStream().tell();
584 for (MCSectionData::const_iterator it = SD->begin(),
585 ie = SD->end(); it != ie; ++it)
586 WriteFragmentData(*this, Layout, *it, OW);
588 // Add section padding.
589 assert(SectionFileSize >= SectionSize && "Invalid section sizes!");
590 OW->WriteZeros(SectionFileSize - SectionSize);
592 assert(OW->getStream().tell() - Start == SectionFileSize);
595 void MCAssembler::Finish() {
596 DEBUG_WITH_TYPE("mc-dump", {
597 llvm::errs() << "assembler backend - pre-layout\n--\n";
600 // Assign section and fragment ordinals, all subsequent backend code is
601 // responsible for updating these in place.
602 unsigned SectionIndex = 0;
603 unsigned FragmentIndex = 0;
604 for (MCAssembler::iterator it = begin(), ie = end(); it != ie; ++it) {
605 it->setOrdinal(SectionIndex++);
607 for (MCSectionData::iterator it2 = it->begin(),
608 ie2 = it->end(); it2 != ie2; ++it2)
609 it2->setOrdinal(FragmentIndex++);
612 // Layout until everything fits.
613 MCAsmLayout Layout(*this);
614 while (LayoutOnce(Layout))
617 DEBUG_WITH_TYPE("mc-dump", {
618 llvm::errs() << "assembler backend - post-relaxation\n--\n";
621 // Finalize the layout, including fragment lowering.
622 FinishLayout(Layout);
624 DEBUG_WITH_TYPE("mc-dump", {
625 llvm::errs() << "assembler backend - final-layout\n--\n";
628 uint64_t StartOffset = OS.tell();
629 llvm::OwningPtr<MCObjectWriter> Writer(getBackend().createObjectWriter(OS));
631 report_fatal_error("unable to create object writer!");
633 // Allow the object writer a chance to perform post-layout binding (for
634 // example, to set the index fields in the symbol data).
635 Writer->ExecutePostLayoutBinding(*this);
637 // Evaluate and apply the fixups, generating relocation entries as necessary.
638 for (MCAssembler::iterator it = begin(), ie = end(); it != ie; ++it) {
639 for (MCSectionData::iterator it2 = it->begin(),
640 ie2 = it->end(); it2 != ie2; ++it2) {
641 MCDataFragment *DF = dyn_cast<MCDataFragment>(it2);
645 for (MCDataFragment::fixup_iterator it3 = DF->fixup_begin(),
646 ie3 = DF->fixup_end(); it3 != ie3; ++it3) {
647 MCAsmFixup &Fixup = *it3;
649 // Evaluate the fixup.
652 if (!EvaluateFixup(Layout, Fixup, DF, Target, FixedValue)) {
653 // The fixup was unresolved, we need a relocation. Inform the object
654 // writer of the relocation, and give it an opportunity to adjust the
655 // fixup value if need be.
656 Writer->RecordRelocation(*this, Layout, DF, Fixup, Target,FixedValue);
659 getBackend().ApplyFixup(Fixup, *DF, FixedValue);
664 // Write the object file.
665 Writer->WriteObject(*this, Layout);
668 stats::ObjectBytes += OS.tell() - StartOffset;
671 bool MCAssembler::FixupNeedsRelaxation(const MCAsmFixup &Fixup,
672 const MCFragment *DF,
673 const MCAsmLayout &Layout) const {
677 // If we cannot resolve the fixup value, it requires relaxation.
680 if (!EvaluateFixup(Layout, Fixup, DF, Target, Value))
683 // Otherwise, relax if the value is too big for a (signed) i8.
685 // FIXME: This is target dependent!
686 return int64_t(Value) != int64_t(int8_t(Value));
689 bool MCAssembler::FragmentNeedsRelaxation(const MCInstFragment *IF,
690 const MCAsmLayout &Layout) const {
691 // If this inst doesn't ever need relaxation, ignore it. This occurs when we
692 // are intentionally pushing out inst fragments, or because we relaxed a
693 // previous instruction to one that doesn't need relaxation.
694 if (!getBackend().MayNeedRelaxation(IF->getInst(), IF->getFixups()))
697 for (MCInstFragment::const_fixup_iterator it = IF->fixup_begin(),
698 ie = IF->fixup_end(); it != ie; ++it)
699 if (FixupNeedsRelaxation(*it, IF, Layout))
705 bool MCAssembler::LayoutOnce(MCAsmLayout &Layout) {
706 ++stats::RelaxationSteps;
708 // Layout the concrete sections and fragments.
709 uint64_t Address = 0;
710 for (MCAsmLayout::iterator it = Layout.begin(),
711 ie = Layout.end(); it != ie; ++it) {
712 // Layout the section fragments and its size.
713 Address = LayoutSection(**it, Layout, Address);
716 // Scan for fragments that need relaxation.
717 bool WasRelaxed = false;
718 for (iterator it = begin(), ie = end(); it != ie; ++it) {
719 MCSectionData &SD = *it;
721 for (MCSectionData::iterator it2 = SD.begin(),
722 ie2 = SD.end(); it2 != ie2; ++it2) {
723 // Check if this is an instruction fragment that needs relaxation.
724 MCInstFragment *IF = dyn_cast<MCInstFragment>(it2);
725 if (!IF || !FragmentNeedsRelaxation(IF, Layout))
728 ++stats::RelaxedInstructions;
730 // FIXME-PERF: We could immediately lower out instructions if we can tell
731 // they are fully resolved, to avoid retesting on later passes.
733 // Relax the fragment.
736 getBackend().RelaxInstruction(IF, Relaxed);
738 // Encode the new instruction.
740 // FIXME-PERF: If it matters, we could let the target do this. It can
741 // probably do so more efficiently in many cases.
742 SmallVector<MCFixup, 4> Fixups;
743 SmallString<256> Code;
744 raw_svector_ostream VecOS(Code);
745 getEmitter().EncodeInstruction(Relaxed, VecOS, Fixups);
748 // Update the instruction fragment.
749 int SlideAmount = Code.size() - IF->getInstSize();
750 IF->setInst(Relaxed);
751 IF->getCode() = Code;
752 IF->getFixups().clear();
753 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
754 MCFixup &F = Fixups[i];
755 IF->getFixups().push_back(MCAsmFixup(F.getOffset(), *F.getValue(),
759 // Update the layout, and remember that we relaxed. If we are relaxing
760 // everything, we can skip this step since nothing will depend on updating
763 Layout.UpdateForSlide(IF, SlideAmount);
771 void MCAssembler::FinishLayout(MCAsmLayout &Layout) {
772 // Lower out any instruction fragments, to simplify the fixup application and
775 // FIXME-PERF: We don't have to do this, but the assumption is that it is
776 // cheap (we will mostly end up eliminating fragments and appending on to data
777 // fragments), so the extra complexity downstream isn't worth it. Evaluate
779 for (iterator it = begin(), ie = end(); it != ie; ++it) {
780 MCSectionData &SD = *it;
782 for (MCSectionData::iterator it2 = SD.begin(),
783 ie2 = SD.end(); it2 != ie2; ++it2) {
784 MCInstFragment *IF = dyn_cast<MCInstFragment>(it2);
788 // Create a new data fragment for the instruction.
790 // FIXME-PERF: Reuse previous data fragment if possible.
791 MCDataFragment *DF = new MCDataFragment();
792 SD.getFragmentList().insert(it2, DF);
794 // Update the data fragments layout data.
796 // FIXME: Add MCAsmLayout utility for this.
797 DF->setParent(IF->getParent());
798 DF->setAtom(IF->getAtom());
799 DF->setOrdinal(IF->getOrdinal());
800 Layout.setFragmentOffset(DF, Layout.getFragmentOffset(IF));
801 Layout.setFragmentEffectiveSize(DF, Layout.getFragmentEffectiveSize(IF));
803 // Copy in the data and the fixups.
804 DF->getContents().append(IF->getCode().begin(), IF->getCode().end());
805 for (unsigned i = 0, e = IF->getFixups().size(); i != e; ++i)
806 DF->getFixups().push_back(IF->getFixups()[i]);
808 // Delete the instruction fragment and update the iterator.
809 SD.getFragmentList().erase(IF);
819 raw_ostream &operator<<(raw_ostream &OS, const MCAsmFixup &AF) {
820 OS << "<MCAsmFixup" << " Offset:" << AF.Offset << " Value:" << *AF.Value
821 << " Kind:" << AF.Kind << ">";
827 void MCFragment::dump() {
828 raw_ostream &OS = llvm::errs();
830 OS << "<MCFragment " << (void*) this << " Offset:" << Offset
831 << " EffectiveSize:" << EffectiveSize;
836 void MCAlignFragment::dump() {
837 raw_ostream &OS = llvm::errs();
839 OS << "<MCAlignFragment ";
840 this->MCFragment::dump();
842 OS << " Alignment:" << getAlignment()
843 << " Value:" << getValue() << " ValueSize:" << getValueSize()
844 << " MaxBytesToEmit:" << getMaxBytesToEmit() << ">";
847 void MCDataFragment::dump() {
848 raw_ostream &OS = llvm::errs();
850 OS << "<MCDataFragment ";
851 this->MCFragment::dump();
854 for (unsigned i = 0, e = getContents().size(); i != e; ++i) {
856 OS << hexdigit((Contents[i] >> 4) & 0xF) << hexdigit(Contents[i] & 0xF);
858 OS << "] (" << getContents().size() << " bytes)";
860 if (!getFixups().empty()) {
863 for (fixup_iterator it = fixup_begin(), ie = fixup_end(); it != ie; ++it) {
864 if (it != fixup_begin()) OS << ",\n ";
873 void MCFillFragment::dump() {
874 raw_ostream &OS = llvm::errs();
876 OS << "<MCFillFragment ";
877 this->MCFragment::dump();
879 OS << " Value:" << getValue() << " ValueSize:" << getValueSize()
880 << " Count:" << getCount() << ">";
883 void MCInstFragment::dump() {
884 raw_ostream &OS = llvm::errs();
886 OS << "<MCInstFragment ";
887 this->MCFragment::dump();
890 getInst().dump_pretty(OS);
894 void MCOrgFragment::dump() {
895 raw_ostream &OS = llvm::errs();
897 OS << "<MCOrgFragment ";
898 this->MCFragment::dump();
900 OS << " Offset:" << getOffset() << " Value:" << getValue() << ">";
903 void MCZeroFillFragment::dump() {
904 raw_ostream &OS = llvm::errs();
906 OS << "<MCZeroFillFragment ";
907 this->MCFragment::dump();
909 OS << " Size:" << getSize() << " Alignment:" << getAlignment() << ">";
912 void MCSectionData::dump() {
913 raw_ostream &OS = llvm::errs();
915 OS << "<MCSectionData";
916 OS << " Alignment:" << getAlignment() << " Address:" << Address
917 << " Size:" << Size << " FileSize:" << FileSize
918 << " Fragments:[\n ";
919 for (iterator it = begin(), ie = end(); it != ie; ++it) {
920 if (it != begin()) OS << ",\n ";
926 void MCSymbolData::dump() {
927 raw_ostream &OS = llvm::errs();
929 OS << "<MCSymbolData Symbol:" << getSymbol()
930 << " Fragment:" << getFragment() << " Offset:" << getOffset()
931 << " Flags:" << getFlags() << " Index:" << getIndex();
933 OS << " (common, size:" << getCommonSize()
934 << " align: " << getCommonAlignment() << ")";
937 if (isPrivateExtern())
938 OS << " (private extern)";
942 void MCAssembler::dump() {
943 raw_ostream &OS = llvm::errs();
945 OS << "<MCAssembler\n";
946 OS << " Sections:[\n ";
947 for (iterator it = begin(), ie = end(); it != ie; ++it) {
948 if (it != begin()) OS << ",\n ";
954 for (symbol_iterator it = symbol_begin(), ie = symbol_end(); it != ie; ++it) {
955 if (it != symbol_begin()) OS << ",\n ";