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/MCContext.h"
15 #include "llvm/MC/MCExpr.h"
16 #include "llvm/MC/MCObjectWriter.h"
17 #include "llvm/MC/MCSection.h"
18 #include "llvm/MC/MCSymbol.h"
19 #include "llvm/MC/MCValue.h"
20 #include "llvm/MC/MCDwarf.h"
21 #include "llvm/MC/MCAsmBackend.h"
22 #include "llvm/ADT/OwningPtr.h"
23 #include "llvm/ADT/Statistic.h"
24 #include "llvm/ADT/StringExtras.h"
25 #include "llvm/ADT/Twine.h"
26 #include "llvm/Support/Debug.h"
27 #include "llvm/Support/ErrorHandling.h"
28 #include "llvm/Support/raw_ostream.h"
29 #include "llvm/Support/TargetRegistry.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()
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::isFragmentUpToDate(const MCFragment *F) const {
64 const MCSectionData &SD = *F->getParent();
65 const MCFragment *LastValid = LastValidFragment.lookup(&SD);
68 assert(LastValid->getParent() == F->getParent());
69 return F->getLayoutOrder() <= LastValid->getLayoutOrder();
72 void MCAsmLayout::Invalidate(MCFragment *F) {
73 // If this fragment wasn't already up-to-date, we don't need to do anything.
74 if (!isFragmentUpToDate(F))
77 // Otherwise, reset the last valid fragment to this fragment.
78 const MCSectionData &SD = *F->getParent();
79 LastValidFragment[&SD] = F;
82 void MCAsmLayout::EnsureValid(const MCFragment *F) const {
83 MCSectionData &SD = *F->getParent();
85 MCFragment *Cur = LastValidFragment[&SD];
89 Cur = Cur->getNextNode();
91 // Advance the layout position until the fragment is up-to-date.
92 while (!isFragmentUpToDate(F)) {
93 const_cast<MCAsmLayout*>(this)->LayoutFragment(Cur);
94 Cur = Cur->getNextNode();
98 uint64_t MCAsmLayout::getFragmentOffset(const MCFragment *F) const {
100 assert(F->Offset != ~UINT64_C(0) && "Address not set!");
104 uint64_t MCAsmLayout::getSymbolOffset(const MCSymbolData *SD) const {
105 const MCSymbol &S = SD->getSymbol();
107 // If this is a variable, then recursively evaluate now.
108 if (S.isVariable()) {
110 if (!S.getVariableValue()->EvaluateAsRelocatable(Target, *this))
111 report_fatal_error("unable to evaluate offset for variable '" +
114 // Verify that any used symbols are defined.
115 if (Target.getSymA() && Target.getSymA()->getSymbol().isUndefined())
116 report_fatal_error("unable to evaluate offset to undefined symbol '" +
117 Target.getSymA()->getSymbol().getName() + "'");
118 if (Target.getSymB() && Target.getSymB()->getSymbol().isUndefined())
119 report_fatal_error("unable to evaluate offset to undefined symbol '" +
120 Target.getSymB()->getSymbol().getName() + "'");
122 uint64_t Offset = Target.getConstant();
123 if (Target.getSymA())
124 Offset += getSymbolOffset(&Assembler.getSymbolData(
125 Target.getSymA()->getSymbol()));
126 if (Target.getSymB())
127 Offset -= getSymbolOffset(&Assembler.getSymbolData(
128 Target.getSymB()->getSymbol()));
132 assert(SD->getFragment() && "Invalid getOffset() on undefined symbol!");
133 return getFragmentOffset(SD->getFragment()) + SD->getOffset();
136 uint64_t MCAsmLayout::getSectionAddressSize(const MCSectionData *SD) const {
137 // The size is the last fragment's end offset.
138 const MCFragment &F = SD->getFragmentList().back();
139 return getFragmentOffset(&F) + getAssembler().computeFragmentSize(*this, F);
142 uint64_t MCAsmLayout::getSectionFileSize(const MCSectionData *SD) const {
143 // Virtual sections have no file size.
144 if (SD->getSection().isVirtualSection())
147 // Otherwise, the file size is the same as the address space size.
148 return getSectionAddressSize(SD);
153 MCFragment::MCFragment() : Kind(FragmentType(~0)) {
156 MCFragment::~MCFragment() {
159 MCFragment::MCFragment(FragmentType _Kind, MCSectionData *_Parent)
160 : Kind(_Kind), Parent(_Parent), Atom(0), Offset(~UINT64_C(0))
163 Parent->getFragmentList().push_back(this);
168 MCSectionData::MCSectionData() : Section(0) {}
170 MCSectionData::MCSectionData(const MCSection &_Section, MCAssembler *A)
171 : Section(&_Section),
172 Ordinal(~UINT32_C(0)),
174 HasInstructions(false)
177 A->getSectionList().push_back(this);
182 MCSymbolData::MCSymbolData() : Symbol(0) {}
184 MCSymbolData::MCSymbolData(const MCSymbol &_Symbol, MCFragment *_Fragment,
185 uint64_t _Offset, MCAssembler *A)
186 : Symbol(&_Symbol), Fragment(_Fragment), Offset(_Offset),
187 IsExternal(false), IsPrivateExtern(false),
188 CommonSize(0), SymbolSize(0), CommonAlign(0),
192 A->getSymbolList().push_back(this);
197 MCAssembler::MCAssembler(MCContext &Context_, MCAsmBackend &Backend_,
198 MCCodeEmitter &Emitter_, MCObjectWriter &Writer_,
200 : Context(Context_), Backend(Backend_), Emitter(Emitter_), Writer(Writer_),
201 OS(OS_), RelaxAll(false), NoExecStack(false), SubsectionsViaSymbols(false)
205 MCAssembler::~MCAssembler() {
208 bool MCAssembler::isSymbolLinkerVisible(const MCSymbol &Symbol) const {
209 // Non-temporary labels should always be visible to the linker.
210 if (!Symbol.isTemporary())
213 // Absolute temporary labels are never visible.
214 if (!Symbol.isInSection())
217 // Otherwise, check if the section requires symbols even for temporary labels.
218 return getBackend().doesSectionRequireSymbols(Symbol.getSection());
221 const MCSymbolData *MCAssembler::getAtom(const MCSymbolData *SD) const {
222 // Linker visible symbols define atoms.
223 if (isSymbolLinkerVisible(SD->getSymbol()))
226 // Absolute and undefined symbols have no defining atom.
227 if (!SD->getFragment())
230 // Non-linker visible symbols in sections which can't be atomized have no
232 if (!getBackend().isSectionAtomizable(
233 SD->getFragment()->getParent()->getSection()))
236 // Otherwise, return the atom for the containing fragment.
237 return SD->getFragment()->getAtom();
240 bool MCAssembler::evaluateFixup(const MCAsmLayout &Layout,
241 const MCFixup &Fixup, const MCFragment *DF,
242 MCValue &Target, uint64_t &Value) const {
243 ++stats::evaluateFixup;
245 if (!Fixup.getValue()->EvaluateAsRelocatable(Target, Layout))
246 getContext().FatalError(Fixup.getLoc(), "expected relocatable expression");
248 bool IsPCRel = Backend.getFixupKindInfo(
249 Fixup.getKind()).Flags & MCFixupKindInfo::FKF_IsPCRel;
253 if (Target.getSymB()) {
255 } else if (!Target.getSymA()) {
258 const MCSymbolRefExpr *A = Target.getSymA();
259 const MCSymbol &SA = A->getSymbol();
260 if (A->getKind() != MCSymbolRefExpr::VK_None ||
261 SA.AliasedSymbol().isUndefined()) {
264 const MCSymbolData &DataA = getSymbolData(SA);
266 getWriter().IsSymbolRefDifferenceFullyResolvedImpl(*this, DataA,
271 IsResolved = Target.isAbsolute();
274 Value = Target.getConstant();
276 if (const MCSymbolRefExpr *A = Target.getSymA()) {
277 const MCSymbol &Sym = A->getSymbol().AliasedSymbol();
279 Value += Layout.getSymbolOffset(&getSymbolData(Sym));
281 if (const MCSymbolRefExpr *B = Target.getSymB()) {
282 const MCSymbol &Sym = B->getSymbol().AliasedSymbol();
284 Value -= Layout.getSymbolOffset(&getSymbolData(Sym));
288 bool ShouldAlignPC = Backend.getFixupKindInfo(Fixup.getKind()).Flags &
289 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits;
290 assert((ShouldAlignPC ? IsPCRel : true) &&
291 "FKF_IsAlignedDownTo32Bits is only allowed on PC-relative fixups!");
294 uint32_t Offset = Layout.getFragmentOffset(DF) + Fixup.getOffset();
296 // A number of ARM fixups in Thumb mode require that the effective PC
297 // address be determined as the 32-bit aligned version of the actual offset.
298 if (ShouldAlignPC) Offset &= ~0x3;
302 // Let the backend adjust the fixup value if necessary.
303 Backend.processFixupValue(*this, Layout, Fixup, DF, Target, Value);
308 uint64_t MCAssembler::computeFragmentSize(const MCAsmLayout &Layout,
309 const MCFragment &F) const {
310 switch (F.getKind()) {
311 case MCFragment::FT_Data:
312 return cast<MCDataFragment>(F).getContents().size();
313 case MCFragment::FT_Fill:
314 return cast<MCFillFragment>(F).getSize();
315 case MCFragment::FT_Inst:
316 return cast<MCInstFragment>(F).getInstSize();
318 case MCFragment::FT_LEB:
319 return cast<MCLEBFragment>(F).getContents().size();
321 case MCFragment::FT_Align: {
322 const MCAlignFragment &AF = cast<MCAlignFragment>(F);
323 unsigned Offset = Layout.getFragmentOffset(&AF);
324 unsigned Size = OffsetToAlignment(Offset, AF.getAlignment());
325 if (Size > AF.getMaxBytesToEmit())
330 case MCFragment::FT_Org: {
331 MCOrgFragment &OF = cast<MCOrgFragment>(F);
332 int64_t TargetLocation;
333 if (!OF.getOffset().EvaluateAsAbsolute(TargetLocation, Layout))
334 report_fatal_error("expected assembly-time absolute expression");
336 // FIXME: We need a way to communicate this error.
337 uint64_t FragmentOffset = Layout.getFragmentOffset(&OF);
338 int64_t Size = TargetLocation - FragmentOffset;
339 if (Size < 0 || Size >= 0x40000000)
340 report_fatal_error("invalid .org offset '" + Twine(TargetLocation) +
341 "' (at offset '" + Twine(FragmentOffset) + "')");
345 case MCFragment::FT_Dwarf:
346 return cast<MCDwarfLineAddrFragment>(F).getContents().size();
347 case MCFragment::FT_DwarfFrame:
348 return cast<MCDwarfCallFrameFragment>(F).getContents().size();
351 llvm_unreachable("invalid fragment kind");
354 void MCAsmLayout::LayoutFragment(MCFragment *F) {
355 MCFragment *Prev = F->getPrevNode();
357 // We should never try to recompute something which is up-to-date.
358 assert(!isFragmentUpToDate(F) && "Attempt to recompute up-to-date fragment!");
359 // We should never try to compute the fragment layout if it's predecessor
361 assert((!Prev || isFragmentUpToDate(Prev)) &&
362 "Attempt to compute fragment before it's predecessor!");
364 ++stats::FragmentLayouts;
366 // Compute fragment offset and size.
369 Offset += Prev->Offset + getAssembler().computeFragmentSize(*this, *Prev);
372 LastValidFragment[F->getParent()] = F;
375 /// WriteFragmentData - Write the \arg F data to the output file.
376 static void WriteFragmentData(const MCAssembler &Asm, const MCAsmLayout &Layout,
377 const MCFragment &F) {
378 MCObjectWriter *OW = &Asm.getWriter();
379 uint64_t Start = OW->getStream().tell();
382 ++stats::EmittedFragments;
384 // FIXME: Embed in fragments instead?
385 uint64_t FragmentSize = Asm.computeFragmentSize(Layout, F);
386 switch (F.getKind()) {
387 case MCFragment::FT_Align: {
388 MCAlignFragment &AF = cast<MCAlignFragment>(F);
389 uint64_t Count = FragmentSize / AF.getValueSize();
391 assert(AF.getValueSize() && "Invalid virtual align in concrete fragment!");
393 // FIXME: This error shouldn't actually occur (the front end should emit
394 // multiple .align directives to enforce the semantics it wants), but is
395 // severe enough that we want to report it. How to handle this?
396 if (Count * AF.getValueSize() != FragmentSize)
397 report_fatal_error("undefined .align directive, value size '" +
398 Twine(AF.getValueSize()) +
399 "' is not a divisor of padding size '" +
400 Twine(FragmentSize) + "'");
402 // See if we are aligning with nops, and if so do that first to try to fill
403 // the Count bytes. Then if that did not fill any bytes or there are any
404 // bytes left to fill use the the Value and ValueSize to fill the rest.
405 // If we are aligning with nops, ask that target to emit the right data.
406 if (AF.hasEmitNops()) {
407 if (!Asm.getBackend().writeNopData(Count, OW))
408 report_fatal_error("unable to write nop sequence of " +
409 Twine(Count) + " bytes");
413 // Otherwise, write out in multiples of the value size.
414 for (uint64_t i = 0; i != Count; ++i) {
415 switch (AF.getValueSize()) {
416 default: llvm_unreachable("Invalid size!");
417 case 1: OW->Write8 (uint8_t (AF.getValue())); break;
418 case 2: OW->Write16(uint16_t(AF.getValue())); break;
419 case 4: OW->Write32(uint32_t(AF.getValue())); break;
420 case 8: OW->Write64(uint64_t(AF.getValue())); break;
426 case MCFragment::FT_Data: {
427 MCDataFragment &DF = cast<MCDataFragment>(F);
428 assert(FragmentSize == DF.getContents().size() && "Invalid size!");
429 OW->WriteBytes(DF.getContents().str());
433 case MCFragment::FT_Fill: {
434 MCFillFragment &FF = cast<MCFillFragment>(F);
436 assert(FF.getValueSize() && "Invalid virtual align in concrete fragment!");
438 for (uint64_t i = 0, e = FF.getSize() / FF.getValueSize(); i != e; ++i) {
439 switch (FF.getValueSize()) {
440 default: llvm_unreachable("Invalid size!");
441 case 1: OW->Write8 (uint8_t (FF.getValue())); break;
442 case 2: OW->Write16(uint16_t(FF.getValue())); break;
443 case 4: OW->Write32(uint32_t(FF.getValue())); break;
444 case 8: OW->Write64(uint64_t(FF.getValue())); break;
450 case MCFragment::FT_Inst: {
451 MCInstFragment &IF = cast<MCInstFragment>(F);
452 OW->WriteBytes(StringRef(IF.getCode().begin(), IF.getCode().size()));
456 case MCFragment::FT_LEB: {
457 MCLEBFragment &LF = cast<MCLEBFragment>(F);
458 OW->WriteBytes(LF.getContents().str());
462 case MCFragment::FT_Org: {
463 MCOrgFragment &OF = cast<MCOrgFragment>(F);
465 for (uint64_t i = 0, e = FragmentSize; i != e; ++i)
466 OW->Write8(uint8_t(OF.getValue()));
471 case MCFragment::FT_Dwarf: {
472 const MCDwarfLineAddrFragment &OF = cast<MCDwarfLineAddrFragment>(F);
473 OW->WriteBytes(OF.getContents().str());
476 case MCFragment::FT_DwarfFrame: {
477 const MCDwarfCallFrameFragment &CF = cast<MCDwarfCallFrameFragment>(F);
478 OW->WriteBytes(CF.getContents().str());
483 assert(OW->getStream().tell() - Start == FragmentSize);
486 void MCAssembler::writeSectionData(const MCSectionData *SD,
487 const MCAsmLayout &Layout) const {
488 // Ignore virtual sections.
489 if (SD->getSection().isVirtualSection()) {
490 assert(Layout.getSectionFileSize(SD) == 0 && "Invalid size for section!");
492 // Check that contents are only things legal inside a virtual section.
493 for (MCSectionData::const_iterator it = SD->begin(),
494 ie = SD->end(); it != ie; ++it) {
495 switch (it->getKind()) {
496 default: llvm_unreachable("Invalid fragment in virtual section!");
497 case MCFragment::FT_Data: {
498 // Check that we aren't trying to write a non-zero contents (or fixups)
499 // into a virtual section. This is to support clients which use standard
500 // directives to fill the contents of virtual sections.
501 MCDataFragment &DF = cast<MCDataFragment>(*it);
502 assert(DF.fixup_begin() == DF.fixup_end() &&
503 "Cannot have fixups in virtual section!");
504 for (unsigned i = 0, e = DF.getContents().size(); i != e; ++i)
505 assert(DF.getContents()[i] == 0 &&
506 "Invalid data value for virtual section!");
509 case MCFragment::FT_Align:
510 // Check that we aren't trying to write a non-zero value into a virtual
512 assert((!cast<MCAlignFragment>(it)->getValueSize() ||
513 !cast<MCAlignFragment>(it)->getValue()) &&
514 "Invalid align in virtual section!");
516 case MCFragment::FT_Fill:
517 assert(!cast<MCFillFragment>(it)->getValueSize() &&
518 "Invalid fill in virtual section!");
526 uint64_t Start = getWriter().getStream().tell();
529 for (MCSectionData::const_iterator it = SD->begin(),
530 ie = SD->end(); it != ie; ++it)
531 WriteFragmentData(*this, Layout, *it);
533 assert(getWriter().getStream().tell() - Start ==
534 Layout.getSectionAddressSize(SD));
538 uint64_t MCAssembler::handleFixup(const MCAsmLayout &Layout,
540 const MCFixup &Fixup) {
541 // Evaluate the fixup.
544 if (!evaluateFixup(Layout, Fixup, &F, Target, FixedValue)) {
545 // The fixup was unresolved, we need a relocation. Inform the object
546 // writer of the relocation, and give it an opportunity to adjust the
547 // fixup value if need be.
548 getWriter().RecordRelocation(*this, Layout, &F, Fixup, Target, FixedValue);
553 void MCAssembler::Finish() {
554 DEBUG_WITH_TYPE("mc-dump", {
555 llvm::errs() << "assembler backend - pre-layout\n--\n";
558 // Create the layout object.
559 MCAsmLayout Layout(*this);
561 // Create dummy fragments and assign section ordinals.
562 unsigned SectionIndex = 0;
563 for (MCAssembler::iterator it = begin(), ie = end(); it != ie; ++it) {
564 // Create dummy fragments to eliminate any empty sections, this simplifies
566 if (it->getFragmentList().empty())
567 new MCDataFragment(it);
569 it->setOrdinal(SectionIndex++);
572 // Assign layout order indices to sections and fragments.
573 for (unsigned i = 0, e = Layout.getSectionOrder().size(); i != e; ++i) {
574 MCSectionData *SD = Layout.getSectionOrder()[i];
575 SD->setLayoutOrder(i);
577 unsigned FragmentIndex = 0;
578 for (MCSectionData::iterator it2 = SD->begin(),
579 ie2 = SD->end(); it2 != ie2; ++it2)
580 it2->setLayoutOrder(FragmentIndex++);
583 // Layout until everything fits.
584 while (layoutOnce(Layout))
587 DEBUG_WITH_TYPE("mc-dump", {
588 llvm::errs() << "assembler backend - post-relaxation\n--\n";
591 // Finalize the layout, including fragment lowering.
592 finishLayout(Layout);
594 DEBUG_WITH_TYPE("mc-dump", {
595 llvm::errs() << "assembler backend - final-layout\n--\n";
598 uint64_t StartOffset = OS.tell();
600 // Allow the object writer a chance to perform post-layout binding (for
601 // example, to set the index fields in the symbol data).
602 getWriter().ExecutePostLayoutBinding(*this, Layout);
604 // Evaluate and apply the fixups, generating relocation entries as necessary.
605 for (MCAssembler::iterator it = begin(), ie = end(); it != ie; ++it) {
606 for (MCSectionData::iterator it2 = it->begin(),
607 ie2 = it->end(); it2 != ie2; ++it2) {
608 MCDataFragment *DF = dyn_cast<MCDataFragment>(it2);
610 for (MCDataFragment::fixup_iterator it3 = DF->fixup_begin(),
611 ie3 = DF->fixup_end(); it3 != ie3; ++it3) {
612 MCFixup &Fixup = *it3;
613 uint64_t FixedValue = handleFixup(Layout, *DF, Fixup);
614 getBackend().applyFixup(Fixup, DF->getContents().data(),
615 DF->getContents().size(), FixedValue);
618 MCInstFragment *IF = dyn_cast<MCInstFragment>(it2);
620 for (MCInstFragment::fixup_iterator it3 = IF->fixup_begin(),
621 ie3 = IF->fixup_end(); it3 != ie3; ++it3) {
622 MCFixup &Fixup = *it3;
623 uint64_t FixedValue = handleFixup(Layout, *IF, Fixup);
624 getBackend().applyFixup(Fixup, IF->getCode().data(),
625 IF->getCode().size(), FixedValue);
631 // Write the object file.
632 getWriter().WriteObject(*this, Layout);
634 stats::ObjectBytes += OS.tell() - StartOffset;
637 bool MCAssembler::fixupNeedsRelaxation(const MCFixup &Fixup,
638 const MCInstFragment *DF,
639 const MCAsmLayout &Layout) const {
643 // If we cannot resolve the fixup value, it requires relaxation.
646 if (!evaluateFixup(Layout, Fixup, DF, Target, Value))
649 return getBackend().fixupNeedsRelaxation(Fixup, Value, DF, Layout);
652 bool MCAssembler::fragmentNeedsRelaxation(const MCInstFragment *IF,
653 const MCAsmLayout &Layout) const {
654 // If this inst doesn't ever need relaxation, ignore it. This occurs when we
655 // are intentionally pushing out inst fragments, or because we relaxed a
656 // previous instruction to one that doesn't need relaxation.
657 if (!getBackend().mayNeedRelaxation(IF->getInst()))
660 for (MCInstFragment::const_fixup_iterator it = IF->fixup_begin(),
661 ie = IF->fixup_end(); it != ie; ++it)
662 if (fixupNeedsRelaxation(*it, IF, Layout))
668 bool MCAssembler::relaxInstruction(MCAsmLayout &Layout,
669 MCInstFragment &IF) {
670 if (!fragmentNeedsRelaxation(&IF, Layout))
673 ++stats::RelaxedInstructions;
675 // FIXME-PERF: We could immediately lower out instructions if we can tell
676 // they are fully resolved, to avoid retesting on later passes.
678 // Relax the fragment.
681 getBackend().relaxInstruction(IF.getInst(), Relaxed);
683 // Encode the new instruction.
685 // FIXME-PERF: If it matters, we could let the target do this. It can
686 // probably do so more efficiently in many cases.
687 SmallVector<MCFixup, 4> Fixups;
688 SmallString<256> Code;
689 raw_svector_ostream VecOS(Code);
690 getEmitter().EncodeInstruction(Relaxed, VecOS, Fixups);
693 // Update the instruction fragment.
696 IF.getFixups().clear();
697 // FIXME: Eliminate copy.
698 for (unsigned i = 0, e = Fixups.size(); i != e; ++i)
699 IF.getFixups().push_back(Fixups[i]);
704 bool MCAssembler::relaxLEB(MCAsmLayout &Layout, MCLEBFragment &LF) {
706 uint64_t OldSize = LF.getContents().size();
707 bool IsAbs = LF.getValue().EvaluateAsAbsolute(Value, Layout);
710 SmallString<8> &Data = LF.getContents();
712 raw_svector_ostream OSE(Data);
714 MCObjectWriter::EncodeSLEB128(Value, OSE);
716 MCObjectWriter::EncodeULEB128(Value, OSE);
718 return OldSize != LF.getContents().size();
721 bool MCAssembler::relaxDwarfLineAddr(MCAsmLayout &Layout,
722 MCDwarfLineAddrFragment &DF) {
723 int64_t AddrDelta = 0;
724 uint64_t OldSize = DF.getContents().size();
725 bool IsAbs = DF.getAddrDelta().EvaluateAsAbsolute(AddrDelta, Layout);
729 LineDelta = DF.getLineDelta();
730 SmallString<8> &Data = DF.getContents();
732 raw_svector_ostream OSE(Data);
733 MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OSE);
735 return OldSize != Data.size();
738 bool MCAssembler::relaxDwarfCallFrameFragment(MCAsmLayout &Layout,
739 MCDwarfCallFrameFragment &DF) {
740 int64_t AddrDelta = 0;
741 uint64_t OldSize = DF.getContents().size();
742 bool IsAbs = DF.getAddrDelta().EvaluateAsAbsolute(AddrDelta, Layout);
745 SmallString<8> &Data = DF.getContents();
747 raw_svector_ostream OSE(Data);
748 MCDwarfFrameEmitter::EncodeAdvanceLoc(AddrDelta, OSE);
750 return OldSize != Data.size();
753 bool MCAssembler::layoutSectionOnce(MCAsmLayout &Layout,
755 MCFragment *FirstInvalidFragment = NULL;
756 // Scan for fragments that need relaxation.
757 for (MCSectionData::iterator it2 = SD.begin(),
758 ie2 = SD.end(); it2 != ie2; ++it2) {
759 // Check if this is an fragment that needs relaxation.
760 bool relaxedFrag = false;
761 switch(it2->getKind()) {
764 case MCFragment::FT_Inst:
765 relaxedFrag = relaxInstruction(Layout, *cast<MCInstFragment>(it2));
767 case MCFragment::FT_Dwarf:
768 relaxedFrag = relaxDwarfLineAddr(Layout,
769 *cast<MCDwarfLineAddrFragment>(it2));
771 case MCFragment::FT_DwarfFrame:
773 relaxDwarfCallFrameFragment(Layout,
774 *cast<MCDwarfCallFrameFragment>(it2));
776 case MCFragment::FT_LEB:
777 relaxedFrag = relaxLEB(Layout, *cast<MCLEBFragment>(it2));
780 // Update the layout, and remember that we relaxed.
781 if (relaxedFrag && !FirstInvalidFragment)
782 FirstInvalidFragment = it2;
784 if (FirstInvalidFragment) {
785 Layout.Invalidate(FirstInvalidFragment);
791 bool MCAssembler::layoutOnce(MCAsmLayout &Layout) {
792 ++stats::RelaxationSteps;
794 bool WasRelaxed = false;
795 for (iterator it = begin(), ie = end(); it != ie; ++it) {
796 MCSectionData &SD = *it;
797 while(layoutSectionOnce(Layout, SD))
804 void MCAssembler::finishLayout(MCAsmLayout &Layout) {
805 // The layout is done. Mark every fragment as valid.
806 for (unsigned int i = 0, n = Layout.getSectionOrder().size(); i != n; ++i) {
807 Layout.getFragmentOffset(&*Layout.getSectionOrder()[i]->rbegin());
815 raw_ostream &operator<<(raw_ostream &OS, const MCFixup &AF) {
816 OS << "<MCFixup" << " Offset:" << AF.getOffset()
817 << " Value:" << *AF.getValue()
818 << " Kind:" << AF.getKind() << ">";
824 void MCFragment::dump() {
825 raw_ostream &OS = llvm::errs();
829 case MCFragment::FT_Align: OS << "MCAlignFragment"; break;
830 case MCFragment::FT_Data: OS << "MCDataFragment"; break;
831 case MCFragment::FT_Fill: OS << "MCFillFragment"; break;
832 case MCFragment::FT_Inst: OS << "MCInstFragment"; break;
833 case MCFragment::FT_Org: OS << "MCOrgFragment"; break;
834 case MCFragment::FT_Dwarf: OS << "MCDwarfFragment"; break;
835 case MCFragment::FT_DwarfFrame: OS << "MCDwarfCallFrameFragment"; break;
836 case MCFragment::FT_LEB: OS << "MCLEBFragment"; break;
839 OS << "<MCFragment " << (void*) this << " LayoutOrder:" << LayoutOrder
840 << " Offset:" << Offset << ">";
843 case MCFragment::FT_Align: {
844 const MCAlignFragment *AF = cast<MCAlignFragment>(this);
845 if (AF->hasEmitNops())
846 OS << " (emit nops)";
848 OS << " Alignment:" << AF->getAlignment()
849 << " Value:" << AF->getValue() << " ValueSize:" << AF->getValueSize()
850 << " MaxBytesToEmit:" << AF->getMaxBytesToEmit() << ">";
853 case MCFragment::FT_Data: {
854 const MCDataFragment *DF = cast<MCDataFragment>(this);
857 const SmallVectorImpl<char> &Contents = DF->getContents();
858 for (unsigned i = 0, e = Contents.size(); i != e; ++i) {
860 OS << hexdigit((Contents[i] >> 4) & 0xF) << hexdigit(Contents[i] & 0xF);
862 OS << "] (" << Contents.size() << " bytes)";
864 if (!DF->getFixups().empty()) {
867 for (MCDataFragment::const_fixup_iterator it = DF->fixup_begin(),
868 ie = DF->fixup_end(); it != ie; ++it) {
869 if (it != DF->fixup_begin()) OS << ",\n ";
876 case MCFragment::FT_Fill: {
877 const MCFillFragment *FF = cast<MCFillFragment>(this);
878 OS << " Value:" << FF->getValue() << " ValueSize:" << FF->getValueSize()
879 << " Size:" << FF->getSize();
882 case MCFragment::FT_Inst: {
883 const MCInstFragment *IF = cast<MCInstFragment>(this);
886 IF->getInst().dump_pretty(OS);
889 case MCFragment::FT_Org: {
890 const MCOrgFragment *OF = cast<MCOrgFragment>(this);
892 OS << " Offset:" << OF->getOffset() << " Value:" << OF->getValue();
895 case MCFragment::FT_Dwarf: {
896 const MCDwarfLineAddrFragment *OF = cast<MCDwarfLineAddrFragment>(this);
898 OS << " AddrDelta:" << OF->getAddrDelta()
899 << " LineDelta:" << OF->getLineDelta();
902 case MCFragment::FT_DwarfFrame: {
903 const MCDwarfCallFrameFragment *CF = cast<MCDwarfCallFrameFragment>(this);
905 OS << " AddrDelta:" << CF->getAddrDelta();
908 case MCFragment::FT_LEB: {
909 const MCLEBFragment *LF = cast<MCLEBFragment>(this);
911 OS << " Value:" << LF->getValue() << " Signed:" << LF->isSigned();
918 void MCSectionData::dump() {
919 raw_ostream &OS = llvm::errs();
921 OS << "<MCSectionData";
922 OS << " Alignment:" << getAlignment() << " Fragments:[\n ";
923 for (iterator it = begin(), ie = end(); it != ie; ++it) {
924 if (it != begin()) OS << ",\n ";
930 void MCSymbolData::dump() {
931 raw_ostream &OS = llvm::errs();
933 OS << "<MCSymbolData Symbol:" << getSymbol()
934 << " Fragment:" << getFragment() << " Offset:" << getOffset()
935 << " Flags:" << getFlags() << " Index:" << getIndex();
937 OS << " (common, size:" << getCommonSize()
938 << " align: " << getCommonAlignment() << ")";
941 if (isPrivateExtern())
942 OS << " (private extern)";
946 void MCAssembler::dump() {
947 raw_ostream &OS = llvm::errs();
949 OS << "<MCAssembler\n";
950 OS << " Sections:[\n ";
951 for (iterator it = begin(), ie = end(); it != ie; ++it) {
952 if (it != begin()) OS << ",\n ";
958 for (symbol_iterator it = symbol_begin(), ie = symbol_end(); it != ie; ++it) {
959 if (it != symbol_begin()) OS << ",\n ";
965 // anchors for MC*Fragment vtables
966 void MCDataFragment::anchor() { }
967 void MCInstFragment::anchor() { }
968 void MCAlignFragment::anchor() { }
969 void MCFillFragment::anchor() { }
970 void MCOrgFragment::anchor() { }
971 void MCLEBFragment::anchor() { }
972 void MCDwarfLineAddrFragment::anchor() { }
973 void MCDwarfCallFrameFragment::anchor() { }