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/MCSection.h"
17 #include "llvm/MC/MCSymbol.h"
18 #include "llvm/MC/MCValue.h"
19 #include "llvm/MC/MCDwarf.h"
20 #include "llvm/ADT/OwningPtr.h"
21 #include "llvm/ADT/Statistic.h"
22 #include "llvm/ADT/StringExtras.h"
23 #include "llvm/ADT/Twine.h"
24 #include "llvm/Support/Debug.h"
25 #include "llvm/Support/ErrorHandling.h"
26 #include "llvm/Support/raw_ostream.h"
27 #include "llvm/Target/TargetRegistry.h"
28 #include "llvm/Target/TargetAsmBackend.h"
35 STATISTIC(EmittedFragments, "Number of emitted assembler fragments");
36 STATISTIC(EvaluateFixup, "Number of evaluated fixups");
37 STATISTIC(FragmentLayouts, "Number of fragment layouts");
38 STATISTIC(ObjectBytes, "Number of emitted object file bytes");
39 STATISTIC(RelaxationSteps, "Number of assembler layout and relaxation steps");
40 STATISTIC(RelaxedInstructions, "Number of relaxed instructions");
44 // FIXME FIXME FIXME: There are number of places in this file where we convert
45 // what is a 64-bit assembler value used for computation into a value in the
46 // object file, which may truncate it. We should detect that truncation where
47 // invalid and report errors back.
51 MCAsmLayout::MCAsmLayout(MCAssembler &Asm)
52 : Assembler(Asm), LastValidFragment(0)
54 // Compute the section layout order. Virtual sections must go last.
55 for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it)
56 if (!it->getSection().isVirtualSection())
57 SectionOrder.push_back(&*it);
58 for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it)
59 if (it->getSection().isVirtualSection())
60 SectionOrder.push_back(&*it);
63 bool MCAsmLayout::isSectionUpToDate(const MCSectionData *SD) const {
64 // The first section is always up-to-date.
65 unsigned Index = SD->getLayoutOrder();
69 // Otherwise, sections are always implicitly computed when the preceeding
70 // fragment is layed out.
71 const MCSectionData *Prev = getSectionOrder()[Index - 1];
72 return isFragmentUpToDate(&(Prev->getFragmentList().back()));
75 bool MCAsmLayout::isFragmentUpToDate(const MCFragment *F) const {
76 return (LastValidFragment &&
77 F->getLayoutOrder() <= LastValidFragment->getLayoutOrder());
80 void MCAsmLayout::Invalidate(MCFragment *F) {
81 // If this fragment wasn't already up-to-date, we don't need to do anything.
82 if (!isFragmentUpToDate(F))
85 // Otherwise, reset the last valid fragment to the predecessor of the
86 // invalidated fragment.
87 LastValidFragment = F->getPrevNode();
88 if (!LastValidFragment) {
89 unsigned Index = F->getParent()->getLayoutOrder();
91 MCSectionData *Prev = getSectionOrder()[Index - 1];
92 LastValidFragment = &(Prev->getFragmentList().back());
97 void MCAsmLayout::EnsureValid(const MCFragment *F) const {
98 // Advance the layout position until the fragment is up-to-date.
99 while (!isFragmentUpToDate(F)) {
100 // Advance to the next fragment.
101 MCFragment *Cur = LastValidFragment;
103 Cur = Cur->getNextNode();
105 unsigned NextIndex = 0;
106 if (LastValidFragment)
107 NextIndex = LastValidFragment->getParent()->getLayoutOrder() + 1;
108 Cur = SectionOrder[NextIndex]->begin();
111 const_cast<MCAsmLayout*>(this)->LayoutFragment(Cur);
115 uint64_t MCAsmLayout::getFragmentEffectiveSize(const MCFragment *F) const {
117 assert(F->EffectiveSize != ~UINT64_C(0) && "Address not set!");
118 return F->EffectiveSize;
121 uint64_t MCAsmLayout::getFragmentOffset(const MCFragment *F) const {
123 assert(F->Offset != ~UINT64_C(0) && "Address not set!");
127 uint64_t MCAsmLayout::getSymbolOffset(const MCSymbolData *SD) const {
128 assert(SD->getFragment() && "Invalid getOffset() on undefined symbol!");
129 return getFragmentOffset(SD->getFragment()) + SD->getOffset();
132 uint64_t MCAsmLayout::getSectionAddressSize(const MCSectionData *SD) const {
133 // The size is the last fragment's end offset.
134 const MCFragment &F = SD->getFragmentList().back();
135 return getFragmentOffset(&F) + getFragmentEffectiveSize(&F);
138 uint64_t MCAsmLayout::getSectionFileSize(const MCSectionData *SD) const {
139 // Virtual sections have no file size.
140 if (SD->getSection().isVirtualSection())
143 // Otherwise, the file size is the same as the address space size.
144 return getSectionAddressSize(SD);
149 MCFragment::MCFragment() : Kind(FragmentType(~0)) {
152 MCFragment::~MCFragment() {
155 MCFragment::MCFragment(FragmentType _Kind, MCSectionData *_Parent)
156 : Kind(_Kind), Parent(_Parent), Atom(0), Offset(~UINT64_C(0)),
157 EffectiveSize(~UINT64_C(0))
160 Parent->getFragmentList().push_back(this);
165 MCSectionData::MCSectionData() : Section(0) {}
167 MCSectionData::MCSectionData(const MCSection &_Section, MCAssembler *A)
168 : Section(&_Section),
169 Ordinal(~UINT32_C(0)),
171 HasInstructions(false)
174 A->getSectionList().push_back(this);
179 MCSymbolData::MCSymbolData() : Symbol(0) {}
181 MCSymbolData::MCSymbolData(const MCSymbol &_Symbol, MCFragment *_Fragment,
182 uint64_t _Offset, MCAssembler *A)
183 : Symbol(&_Symbol), Fragment(_Fragment), Offset(_Offset),
184 IsExternal(false), IsPrivateExtern(false),
185 CommonSize(0), SymbolSize(0), CommonAlign(0),
189 A->getSymbolList().push_back(this);
194 MCAssembler::MCAssembler(MCContext &_Context, TargetAsmBackend &_Backend,
195 MCCodeEmitter &_Emitter, raw_ostream &_OS)
196 : Context(_Context), Backend(_Backend), Emitter(_Emitter),
197 OS(_OS), RelaxAll(false), SubsectionsViaSymbols(false)
201 MCAssembler::~MCAssembler() {
204 bool MCAssembler::isSymbolLinkerVisible(const MCSymbol &Symbol) const {
205 // Non-temporary labels should always be visible to the linker.
206 if (!Symbol.isTemporary())
209 // Absolute temporary labels are never visible.
210 if (!Symbol.isInSection())
213 // Otherwise, check if the section requires symbols even for temporary labels.
214 return getBackend().doesSectionRequireSymbols(Symbol.getSection());
217 const MCSymbolData *MCAssembler::getAtom(const MCSymbolData *SD) const {
218 // Linker visible symbols define atoms.
219 if (isSymbolLinkerVisible(SD->getSymbol()))
222 // Absolute and undefined symbols have no defining atom.
223 if (!SD->getFragment())
226 // Non-linker visible symbols in sections which can't be atomized have no
228 if (!getBackend().isSectionAtomizable(
229 SD->getFragment()->getParent()->getSection()))
232 // Otherwise, return the atom for the containing fragment.
233 return SD->getFragment()->getAtom();
236 bool MCAssembler::EvaluateFixup(const MCObjectWriter &Writer,
237 const MCAsmLayout &Layout,
238 const MCFixup &Fixup, const MCFragment *DF,
239 MCValue &Target, uint64_t &Value) const {
240 ++stats::EvaluateFixup;
242 if (!Fixup.getValue()->EvaluateAsRelocatable(Target, &Layout))
243 report_fatal_error("expected relocatable expression");
245 // FIXME: How do non-scattered symbols work in ELF? I presume the linker
246 // doesn't support small relocations, but then under what criteria does the
247 // assembler allow symbol differences?
249 Value = Target.getConstant();
251 bool IsPCRel = Emitter.getFixupKindInfo(
252 Fixup.getKind()).Flags & MCFixupKindInfo::FKF_IsPCRel;
253 bool IsResolved = true;
254 if (const MCSymbolRefExpr *A = Target.getSymA()) {
255 const MCSymbol &Sym = A->getSymbol().AliasedSymbol();
257 Value += Layout.getSymbolOffset(&getSymbolData(Sym));
261 if (const MCSymbolRefExpr *B = Target.getSymB()) {
262 const MCSymbol &Sym = B->getSymbol().AliasedSymbol();
264 Value -= Layout.getSymbolOffset(&getSymbolData(Sym));
270 IsResolved = Writer.IsFixupFullyResolved(*this, Target, IsPCRel, DF);
273 Value -= Layout.getFragmentOffset(DF) + Fixup.getOffset();
278 uint64_t MCAssembler::ComputeFragmentSize(const MCFragment &F,
279 uint64_t FragmentOffset) const {
280 switch (F.getKind()) {
281 case MCFragment::FT_Data:
282 return cast<MCDataFragment>(F).getContents().size();
283 case MCFragment::FT_Fill:
284 return cast<MCFillFragment>(F).getSize();
285 case MCFragment::FT_Inst:
286 return cast<MCInstFragment>(F).getInstSize();
288 case MCFragment::FT_LEB:
289 return cast<MCLEBFragment>(F).getContents().size();
291 case MCFragment::FT_Align: {
292 const MCAlignFragment &AF = cast<MCAlignFragment>(F);
294 uint64_t Size = OffsetToAlignment(FragmentOffset, AF.getAlignment());
296 // Honor MaxBytesToEmit.
297 if (Size > AF.getMaxBytesToEmit())
303 case MCFragment::FT_Org:
304 return cast<MCOrgFragment>(F).getSize();
306 case MCFragment::FT_Dwarf:
307 return cast<MCDwarfLineAddrFragment>(F).getContents().size();
310 assert(0 && "invalid fragment kind");
314 void MCAsmLayout::LayoutFile() {
315 // Initialize the first section and set the valid fragment layout point. All
316 // actual layout computations are done lazily.
317 LastValidFragment = 0;
320 void MCAsmLayout::LayoutFragment(MCFragment *F) {
321 MCFragment *Prev = F->getPrevNode();
323 // We should never try to recompute something which is up-to-date.
324 assert(!isFragmentUpToDate(F) && "Attempt to recompute up-to-date fragment!");
325 // We should never try to compute the fragment layout if the section isn't
327 assert(isSectionUpToDate(F->getParent()) &&
328 "Attempt to compute fragment before it's section!");
329 // We should never try to compute the fragment layout if it's predecessor
331 assert((!Prev || isFragmentUpToDate(Prev)) &&
332 "Attempt to compute fragment before it's predecessor!");
334 ++stats::FragmentLayouts;
336 // Compute fragment offset and size.
339 Offset += Prev->Offset + Prev->EffectiveSize;
342 F->EffectiveSize = getAssembler().ComputeFragmentSize(*F, F->Offset);
343 LastValidFragment = F;
346 /// WriteFragmentData - Write the \arg F data to the output file.
347 static void WriteFragmentData(const MCAssembler &Asm, const MCAsmLayout &Layout,
348 const MCFragment &F, MCObjectWriter *OW) {
349 uint64_t Start = OW->getStream().tell();
352 ++stats::EmittedFragments;
354 // FIXME: Embed in fragments instead?
355 uint64_t FragmentSize = Layout.getFragmentEffectiveSize(&F);
356 switch (F.getKind()) {
357 case MCFragment::FT_Align: {
358 MCAlignFragment &AF = cast<MCAlignFragment>(F);
359 uint64_t Count = FragmentSize / AF.getValueSize();
361 assert(AF.getValueSize() && "Invalid virtual align in concrete fragment!");
363 // FIXME: This error shouldn't actually occur (the front end should emit
364 // multiple .align directives to enforce the semantics it wants), but is
365 // severe enough that we want to report it. How to handle this?
366 if (Count * AF.getValueSize() != FragmentSize)
367 report_fatal_error("undefined .align directive, value size '" +
368 Twine(AF.getValueSize()) +
369 "' is not a divisor of padding size '" +
370 Twine(FragmentSize) + "'");
372 // See if we are aligning with nops, and if so do that first to try to fill
373 // the Count bytes. Then if that did not fill any bytes or there are any
374 // bytes left to fill use the the Value and ValueSize to fill the rest.
375 // If we are aligning with nops, ask that target to emit the right data.
376 if (AF.hasEmitNops()) {
377 if (!Asm.getBackend().WriteNopData(Count, OW))
378 report_fatal_error("unable to write nop sequence of " +
379 Twine(Count) + " bytes");
383 // Otherwise, write out in multiples of the value size.
384 for (uint64_t i = 0; i != Count; ++i) {
385 switch (AF.getValueSize()) {
387 assert(0 && "Invalid size!");
388 case 1: OW->Write8 (uint8_t (AF.getValue())); break;
389 case 2: OW->Write16(uint16_t(AF.getValue())); break;
390 case 4: OW->Write32(uint32_t(AF.getValue())); break;
391 case 8: OW->Write64(uint64_t(AF.getValue())); break;
397 case MCFragment::FT_Data: {
398 MCDataFragment &DF = cast<MCDataFragment>(F);
399 assert(FragmentSize == DF.getContents().size() && "Invalid size!");
400 OW->WriteBytes(DF.getContents().str());
404 case MCFragment::FT_Fill: {
405 MCFillFragment &FF = cast<MCFillFragment>(F);
407 assert(FF.getValueSize() && "Invalid virtual align in concrete fragment!");
409 for (uint64_t i = 0, e = FF.getSize() / FF.getValueSize(); i != e; ++i) {
410 switch (FF.getValueSize()) {
412 assert(0 && "Invalid size!");
413 case 1: OW->Write8 (uint8_t (FF.getValue())); break;
414 case 2: OW->Write16(uint16_t(FF.getValue())); break;
415 case 4: OW->Write32(uint32_t(FF.getValue())); break;
416 case 8: OW->Write64(uint64_t(FF.getValue())); break;
422 case MCFragment::FT_Inst: {
423 MCInstFragment &IF = cast<MCInstFragment>(F);
424 OW->WriteBytes(StringRef(IF.getCode().begin(), IF.getCode().size()));
428 case MCFragment::FT_LEB: {
429 MCLEBFragment &LF = cast<MCLEBFragment>(F);
430 OW->WriteBytes(LF.getContents().str());
434 case MCFragment::FT_Org: {
435 MCOrgFragment &OF = cast<MCOrgFragment>(F);
437 for (uint64_t i = 0, e = FragmentSize; i != e; ++i)
438 OW->Write8(uint8_t(OF.getValue()));
443 case MCFragment::FT_Dwarf: {
444 const MCDwarfLineAddrFragment &OF = cast<MCDwarfLineAddrFragment>(F);
445 OW->WriteBytes(OF.getContents().str());
450 assert(OW->getStream().tell() - Start == FragmentSize);
453 void MCAssembler::WriteSectionData(const MCSectionData *SD,
454 const MCAsmLayout &Layout,
455 MCObjectWriter *OW) const {
456 // Ignore virtual sections.
457 if (SD->getSection().isVirtualSection()) {
458 assert(Layout.getSectionFileSize(SD) == 0 && "Invalid size for section!");
460 // Check that contents are only things legal inside a virtual section.
461 for (MCSectionData::const_iterator it = SD->begin(),
462 ie = SD->end(); it != ie; ++it) {
463 switch (it->getKind()) {
465 assert(0 && "Invalid fragment in virtual section!");
466 case MCFragment::FT_Data: {
467 // Check that we aren't trying to write a non-zero contents (or fixups)
468 // into a virtual section. This is to support clients which use standard
469 // directives to fill the contents of virtual sections.
470 MCDataFragment &DF = cast<MCDataFragment>(*it);
471 assert(DF.fixup_begin() == DF.fixup_end() &&
472 "Cannot have fixups in virtual section!");
473 for (unsigned i = 0, e = DF.getContents().size(); i != e; ++i)
474 assert(DF.getContents()[i] == 0 &&
475 "Invalid data value for virtual section!");
478 case MCFragment::FT_Align:
479 // Check that we aren't trying to write a non-zero value into a virtual
481 assert((!cast<MCAlignFragment>(it)->getValueSize() ||
482 !cast<MCAlignFragment>(it)->getValue()) &&
483 "Invalid align in virtual section!");
485 case MCFragment::FT_Fill:
486 assert(!cast<MCFillFragment>(it)->getValueSize() &&
487 "Invalid fill in virtual section!");
495 uint64_t Start = OW->getStream().tell();
498 for (MCSectionData::const_iterator it = SD->begin(),
499 ie = SD->end(); it != ie; ++it)
500 WriteFragmentData(*this, Layout, *it, OW);
502 assert(OW->getStream().tell() - Start == Layout.getSectionAddressSize(SD));
506 uint64_t MCAssembler::HandleFixup(MCObjectWriter &Writer,
507 const MCAsmLayout &Layout,
509 const MCFixup &Fixup) {
510 // Evaluate the fixup.
513 if (!EvaluateFixup(Writer, Layout, Fixup, &F, Target, FixedValue)) {
514 // The fixup was unresolved, we need a relocation. Inform the object
515 // writer of the relocation, and give it an opportunity to adjust the
516 // fixup value if need be.
517 Writer.RecordRelocation(*this, Layout, &F, Fixup, Target, FixedValue);
522 void MCAssembler::Finish(MCObjectWriter *Writer) {
523 DEBUG_WITH_TYPE("mc-dump", {
524 llvm::errs() << "assembler backend - pre-layout\n--\n";
527 // Create the layout object.
528 MCAsmLayout Layout(*this);
532 // Create dummy fragments and assign section ordinals.
533 unsigned SectionIndex = 0;
534 for (MCAssembler::iterator it = begin(), ie = end(); it != ie; ++it) {
535 // Create dummy fragments to eliminate any empty sections, this simplifies
537 if (it->getFragmentList().empty())
538 new MCDataFragment(it);
540 it->setOrdinal(SectionIndex++);
543 // Assign layout order indices to sections and fragments.
544 unsigned FragmentIndex = 0;
545 for (unsigned i = 0, e = Layout.getSectionOrder().size(); i != e; ++i) {
546 MCSectionData *SD = Layout.getSectionOrder()[i];
547 SD->setLayoutOrder(i);
549 for (MCSectionData::iterator it2 = SD->begin(),
550 ie2 = SD->end(); it2 != ie2; ++it2)
551 it2->setLayoutOrder(FragmentIndex++);
554 llvm::OwningPtr<MCObjectWriter> OwnWriter(0);
556 //no custom Writer_ : create the default one life-managed by OwningPtr
557 OwnWriter.reset(getBackend().createObjectWriter(OS));
558 Writer = OwnWriter.get();
560 report_fatal_error("unable to create object writer!");
563 // Layout until everything fits.
564 while (LayoutOnce(*Writer, Layout))
567 DEBUG_WITH_TYPE("mc-dump", {
568 llvm::errs() << "assembler backend - post-relaxation\n--\n";
571 // Finalize the layout, including fragment lowering.
572 FinishLayout(Layout);
574 DEBUG_WITH_TYPE("mc-dump", {
575 llvm::errs() << "assembler backend - final-layout\n--\n";
578 uint64_t StartOffset = OS.tell();
580 // Allow the object writer a chance to perform post-layout binding (for
581 // example, to set the index fields in the symbol data).
582 Writer->ExecutePostLayoutBinding(*this, Layout);
584 // Evaluate and apply the fixups, generating relocation entries as necessary.
585 for (MCAssembler::iterator it = begin(), ie = end(); it != ie; ++it) {
586 for (MCSectionData::iterator it2 = it->begin(),
587 ie2 = it->end(); it2 != ie2; ++it2) {
588 MCDataFragment *DF = dyn_cast<MCDataFragment>(it2);
590 for (MCDataFragment::fixup_iterator it3 = DF->fixup_begin(),
591 ie3 = DF->fixup_end(); it3 != ie3; ++it3) {
592 MCFixup &Fixup = *it3;
593 uint64_t FixedValue = HandleFixup(*Writer, Layout, *DF, Fixup);
594 getBackend().ApplyFixup(Fixup, DF->getContents().data(),
595 DF->getContents().size(), FixedValue);
598 MCInstFragment *IF = dyn_cast<MCInstFragment>(it2);
600 for (MCInstFragment::fixup_iterator it3 = IF->fixup_begin(),
601 ie3 = IF->fixup_end(); it3 != ie3; ++it3) {
602 MCFixup &Fixup = *it3;
603 uint64_t FixedValue = HandleFixup(*Writer, Layout, *IF, Fixup);
604 getBackend().ApplyFixup(Fixup, IF->getCode().data(),
605 IF->getCode().size(), FixedValue);
611 // Write the object file.
612 Writer->WriteObject(*this, Layout);
614 stats::ObjectBytes += OS.tell() - StartOffset;
617 bool MCAssembler::FixupNeedsRelaxation(const MCObjectWriter &Writer,
618 const MCFixup &Fixup,
619 const MCFragment *DF,
620 const MCAsmLayout &Layout) const {
624 // If we cannot resolve the fixup value, it requires relaxation.
627 if (!EvaluateFixup(Writer, Layout, Fixup, DF, Target, Value))
630 // Otherwise, relax if the value is too big for a (signed) i8.
632 // FIXME: This is target dependent!
633 return int64_t(Value) != int64_t(int8_t(Value));
636 bool MCAssembler::FragmentNeedsRelaxation(const MCObjectWriter &Writer,
637 const MCInstFragment *IF,
638 const MCAsmLayout &Layout) const {
639 // If this inst doesn't ever need relaxation, ignore it. This occurs when we
640 // are intentionally pushing out inst fragments, or because we relaxed a
641 // previous instruction to one that doesn't need relaxation.
642 if (!getBackend().MayNeedRelaxation(IF->getInst()))
645 for (MCInstFragment::const_fixup_iterator it = IF->fixup_begin(),
646 ie = IF->fixup_end(); it != ie; ++it)
647 if (FixupNeedsRelaxation(Writer, *it, IF, Layout))
653 bool MCAssembler::RelaxInstruction(const MCObjectWriter &Writer,
655 MCInstFragment &IF) {
656 if (!FragmentNeedsRelaxation(Writer, &IF, Layout))
659 ++stats::RelaxedInstructions;
661 // FIXME-PERF: We could immediately lower out instructions if we can tell
662 // they are fully resolved, to avoid retesting on later passes.
664 // Relax the fragment.
667 getBackend().RelaxInstruction(IF.getInst(), Relaxed);
669 // Encode the new instruction.
671 // FIXME-PERF: If it matters, we could let the target do this. It can
672 // probably do so more efficiently in many cases.
673 SmallVector<MCFixup, 4> Fixups;
674 SmallString<256> Code;
675 raw_svector_ostream VecOS(Code);
676 getEmitter().EncodeInstruction(Relaxed, VecOS, Fixups);
679 // Update the instruction fragment.
682 IF.getFixups().clear();
683 // FIXME: Eliminate copy.
684 for (unsigned i = 0, e = Fixups.size(); i != e; ++i)
685 IF.getFixups().push_back(Fixups[i]);
690 bool MCAssembler::RelaxOrg(const MCObjectWriter &Writer,
693 int64_t TargetLocation;
694 if (!OF.getOffset().EvaluateAsAbsolute(TargetLocation, Layout))
695 report_fatal_error("expected assembly-time absolute expression");
697 // FIXME: We need a way to communicate this error.
698 uint64_t FragmentOffset = Layout.getFragmentOffset(&OF);
699 int64_t Offset = TargetLocation - FragmentOffset;
700 if (Offset < 0 || Offset >= 0x40000000)
701 report_fatal_error("invalid .org offset '" + Twine(TargetLocation) +
702 "' (at offset '" + Twine(FragmentOffset) + "')");
704 unsigned OldSize = OF.getSize();
706 return OldSize != OF.getSize();
709 bool MCAssembler::RelaxLEB(const MCObjectWriter &Writer,
713 uint64_t OldSize = LF.getContents().size();
714 LF.getValue().EvaluateAsAbsolute(Value, Layout);
715 SmallString<8> &Data = LF.getContents();
717 raw_svector_ostream OSE(Data);
719 MCObjectWriter::EncodeSLEB128(Value, OSE);
721 MCObjectWriter::EncodeULEB128(Value, OSE);
723 return OldSize != LF.getContents().size();
726 bool MCAssembler::RelaxDwarfLineAddr(const MCObjectWriter &Writer,
728 MCDwarfLineAddrFragment &DF) {
729 int64_t AddrDelta = 0;
730 uint64_t OldSize = DF.getContents().size();
731 DF.getAddrDelta().EvaluateAsAbsolute(AddrDelta, Layout);
733 LineDelta = DF.getLineDelta();
734 SmallString<8> &Data = DF.getContents();
736 raw_svector_ostream OSE(Data);
737 MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OSE);
739 return OldSize != Data.size();
742 bool MCAssembler::LayoutOnce(const MCObjectWriter &Writer,
743 MCAsmLayout &Layout) {
744 ++stats::RelaxationSteps;
746 // Layout the sections in order.
749 // Scan for fragments that need relaxation.
750 bool WasRelaxed = false;
751 for (iterator it = begin(), ie = end(); it != ie; ++it) {
752 MCSectionData &SD = *it;
754 for (MCSectionData::iterator it2 = SD.begin(),
755 ie2 = SD.end(); it2 != ie2; ++it2) {
756 // Check if this is an fragment that needs relaxation.
757 bool relaxedFrag = false;
758 switch(it2->getKind()) {
761 case MCFragment::FT_Inst:
762 relaxedFrag = RelaxInstruction(Writer, Layout,
763 *cast<MCInstFragment>(it2));
765 case MCFragment::FT_Org:
766 relaxedFrag = RelaxOrg(Writer, Layout, *cast<MCOrgFragment>(it2));
768 case MCFragment::FT_Dwarf:
769 relaxedFrag = RelaxDwarfLineAddr(Writer, Layout,
770 *cast<MCDwarfLineAddrFragment>(it2));
772 case MCFragment::FT_LEB:
773 relaxedFrag = RelaxLEB(Writer, Layout, *cast<MCLEBFragment>(it2));
776 // Update the layout, and remember that we relaxed.
778 Layout.Invalidate(it2);
779 WasRelaxed |= relaxedFrag;
786 void MCAssembler::FinishLayout(MCAsmLayout &Layout) {
787 // Lower out any instruction fragments, to simplify the fixup application and
790 // FIXME-PERF: We don't have to do this, but the assumption is that it is
791 // cheap (we will mostly end up eliminating fragments and appending on to data
792 // fragments), so the extra complexity downstream isn't worth it. Evaluate
795 // The layout is done. Mark every fragment as valid.
796 Layout.getFragmentOffset(&*Layout.getSectionOrder().back()->rbegin());
803 raw_ostream &operator<<(raw_ostream &OS, const MCFixup &AF) {
804 OS << "<MCFixup" << " Offset:" << AF.getOffset()
805 << " Value:" << *AF.getValue()
806 << " Kind:" << AF.getKind() << ">";
812 void MCFragment::dump() {
813 raw_ostream &OS = llvm::errs();
817 case MCFragment::FT_Align: OS << "MCAlignFragment"; break;
818 case MCFragment::FT_Data: OS << "MCDataFragment"; break;
819 case MCFragment::FT_Fill: OS << "MCFillFragment"; break;
820 case MCFragment::FT_Inst: OS << "MCInstFragment"; break;
821 case MCFragment::FT_Org: OS << "MCOrgFragment"; break;
822 case MCFragment::FT_Dwarf: OS << "MCDwarfFragment"; break;
823 case MCFragment::FT_LEB: OS << "MCLEBFragment"; break;
826 OS << "<MCFragment " << (void*) this << " LayoutOrder:" << LayoutOrder
827 << " Offset:" << Offset << " EffectiveSize:" << EffectiveSize << ">";
830 case MCFragment::FT_Align: {
831 const MCAlignFragment *AF = cast<MCAlignFragment>(this);
832 if (AF->hasEmitNops())
833 OS << " (emit nops)";
835 OS << " Alignment:" << AF->getAlignment()
836 << " Value:" << AF->getValue() << " ValueSize:" << AF->getValueSize()
837 << " MaxBytesToEmit:" << AF->getMaxBytesToEmit() << ">";
840 case MCFragment::FT_Data: {
841 const MCDataFragment *DF = cast<MCDataFragment>(this);
844 const SmallVectorImpl<char> &Contents = DF->getContents();
845 for (unsigned i = 0, e = Contents.size(); i != e; ++i) {
847 OS << hexdigit((Contents[i] >> 4) & 0xF) << hexdigit(Contents[i] & 0xF);
849 OS << "] (" << Contents.size() << " bytes)";
851 if (!DF->getFixups().empty()) {
854 for (MCDataFragment::const_fixup_iterator it = DF->fixup_begin(),
855 ie = DF->fixup_end(); it != ie; ++it) {
856 if (it != DF->fixup_begin()) OS << ",\n ";
863 case MCFragment::FT_Fill: {
864 const MCFillFragment *FF = cast<MCFillFragment>(this);
865 OS << " Value:" << FF->getValue() << " ValueSize:" << FF->getValueSize()
866 << " Size:" << FF->getSize();
869 case MCFragment::FT_Inst: {
870 const MCInstFragment *IF = cast<MCInstFragment>(this);
873 IF->getInst().dump_pretty(OS);
876 case MCFragment::FT_Org: {
877 const MCOrgFragment *OF = cast<MCOrgFragment>(this);
879 OS << " Offset:" << OF->getOffset() << " Value:" << OF->getValue();
882 case MCFragment::FT_Dwarf: {
883 const MCDwarfLineAddrFragment *OF = cast<MCDwarfLineAddrFragment>(this);
885 OS << " AddrDelta:" << OF->getAddrDelta()
886 << " LineDelta:" << OF->getLineDelta();
889 case MCFragment::FT_LEB: {
890 const MCLEBFragment *LF = cast<MCLEBFragment>(this);
892 OS << " Value:" << LF->getValue() << " Signed:" << LF->isSigned();
899 void MCSectionData::dump() {
900 raw_ostream &OS = llvm::errs();
902 OS << "<MCSectionData";
903 OS << " Alignment:" << getAlignment() << " Fragments:[\n ";
904 for (iterator it = begin(), ie = end(); it != ie; ++it) {
905 if (it != begin()) OS << ",\n ";
911 void MCSymbolData::dump() {
912 raw_ostream &OS = llvm::errs();
914 OS << "<MCSymbolData Symbol:" << getSymbol()
915 << " Fragment:" << getFragment() << " Offset:" << getOffset()
916 << " Flags:" << getFlags() << " Index:" << getIndex();
918 OS << " (common, size:" << getCommonSize()
919 << " align: " << getCommonAlignment() << ")";
922 if (isPrivateExtern())
923 OS << " (private extern)";
927 void MCAssembler::dump() {
928 raw_ostream &OS = llvm::errs();
930 OS << "<MCAssembler\n";
931 OS << " Sections:[\n ";
932 for (iterator it = begin(), ie = end(); it != ie; ++it) {
933 if (it != begin()) OS << ",\n ";
939 for (symbol_iterator it = symbol_begin(), ie = symbol_end(); it != ie; ++it) {
940 if (it != symbol_begin()) OS << ",\n ";