1 //===- MCCodeView.h - Machine Code CodeView support -------------*- C++ -*-===//
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 // Holds state from .cv_file and .cv_loc directives for later emission.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/MC/MCCodeView.h"
15 #include "llvm/ADT/STLExtras.h"
16 #include "llvm/ADT/StringExtras.h"
17 #include "llvm/DebugInfo/CodeView/CodeView.h"
18 #include "llvm/DebugInfo/CodeView/Line.h"
19 #include "llvm/DebugInfo/CodeView/SymbolRecord.h"
20 #include "llvm/MC/MCAsmLayout.h"
21 #include "llvm/MC/MCContext.h"
22 #include "llvm/MC/MCObjectStreamer.h"
23 #include "llvm/MC/MCValue.h"
24 #include "llvm/Support/EndianStream.h"
27 using namespace llvm::codeview;
29 CodeViewContext::CodeViewContext() {}
31 CodeViewContext::~CodeViewContext() {
32 // If someone inserted strings into the string table but never actually
33 // emitted them somewhere, clean up the fragment.
34 if (!InsertedStrTabFragment)
35 delete StrTabFragment;
38 /// This is a valid number for use with .cv_loc if we've already seen a .cv_file
40 bool CodeViewContext::isValidFileNumber(unsigned FileNumber) const {
41 unsigned Idx = FileNumber - 1;
42 if (Idx < Files.size())
43 return Files[Idx].Assigned;
47 bool CodeViewContext::addFile(MCStreamer &OS, unsigned FileNumber,
49 ArrayRef<uint8_t> ChecksumBytes,
50 uint8_t ChecksumKind) {
51 assert(FileNumber > 0);
52 auto FilenameOffset = addToStringTable(Filename);
53 Filename = FilenameOffset.first;
54 unsigned Idx = FileNumber - 1;
55 if (Idx >= Files.size())
56 Files.resize(Idx + 1);
61 if (Files[Idx].Assigned)
64 FilenameOffset = addToStringTable(Filename);
65 Filename = FilenameOffset.first;
66 unsigned Offset = FilenameOffset.second;
68 auto ChecksumOffsetSymbol =
69 OS.getContext().createTempSymbol("checksum_offset", false);
70 Files[Idx].StringTableOffset = Offset;
71 Files[Idx].ChecksumTableOffset = ChecksumOffsetSymbol;
72 Files[Idx].Assigned = true;
73 Files[Idx].Checksum = ChecksumBytes;
74 Files[Idx].ChecksumKind = ChecksumKind;
79 MCCVFunctionInfo *CodeViewContext::getCVFunctionInfo(unsigned FuncId) {
80 if (FuncId >= Functions.size())
82 if (Functions[FuncId].isUnallocatedFunctionInfo())
84 return &Functions[FuncId];
87 bool CodeViewContext::recordFunctionId(unsigned FuncId) {
88 if (FuncId >= Functions.size())
89 Functions.resize(FuncId + 1);
91 // Return false if this function info was already allocated.
92 if (!Functions[FuncId].isUnallocatedFunctionInfo())
95 // Mark this as an allocated normal function, and leave the rest alone.
96 Functions[FuncId].ParentFuncIdPlusOne = MCCVFunctionInfo::FunctionSentinel;
100 bool CodeViewContext::recordInlinedCallSiteId(unsigned FuncId, unsigned IAFunc,
101 unsigned IAFile, unsigned IALine,
103 if (FuncId >= Functions.size())
104 Functions.resize(FuncId + 1);
106 // Return false if this function info was already allocated.
107 if (!Functions[FuncId].isUnallocatedFunctionInfo())
110 MCCVFunctionInfo::LineInfo InlinedAt;
111 InlinedAt.File = IAFile;
112 InlinedAt.Line = IALine;
113 InlinedAt.Col = IACol;
115 // Mark this as an inlined call site and record call site line info.
116 MCCVFunctionInfo *Info = &Functions[FuncId];
117 Info->ParentFuncIdPlusOne = IAFunc + 1;
118 Info->InlinedAt = InlinedAt;
120 // Walk up the call chain adding this function id to the InlinedAtMap of all
121 // transitive callers until we hit a real function.
122 while (Info->isInlinedCallSite()) {
123 InlinedAt = Info->InlinedAt;
124 Info = getCVFunctionInfo(Info->getParentFuncId());
125 Info->InlinedAtMap[FuncId] = InlinedAt;
131 MCDataFragment *CodeViewContext::getStringTableFragment() {
132 if (!StrTabFragment) {
133 StrTabFragment = new MCDataFragment();
134 // Start a new string table out with a null byte.
135 StrTabFragment->getContents().push_back('\0');
137 return StrTabFragment;
140 std::pair<StringRef, unsigned> CodeViewContext::addToStringTable(StringRef S) {
141 SmallVectorImpl<char> &Contents = getStringTableFragment()->getContents();
143 StringTable.insert(std::make_pair(S, unsigned(Contents.size())));
144 // Return the string from the table, since it is stable.
145 std::pair<StringRef, unsigned> Ret =
146 std::make_pair(Insertion.first->first(), Insertion.first->second);
147 if (Insertion.second) {
148 // The string map key is always null terminated.
149 Contents.append(Ret.first.begin(), Ret.first.end() + 1);
154 unsigned CodeViewContext::getStringTableOffset(StringRef S) {
155 // A string table offset of zero is always the empty string.
158 auto I = StringTable.find(S);
159 assert(I != StringTable.end());
163 void CodeViewContext::emitStringTable(MCObjectStreamer &OS) {
164 MCContext &Ctx = OS.getContext();
165 MCSymbol *StringBegin = Ctx.createTempSymbol("strtab_begin", false),
166 *StringEnd = Ctx.createTempSymbol("strtab_end", false);
168 OS.EmitIntValue(unsigned(DebugSubsectionKind::StringTable), 4);
169 OS.emitAbsoluteSymbolDiff(StringEnd, StringBegin, 4);
170 OS.EmitLabel(StringBegin);
172 // Put the string table data fragment here, if we haven't already put it
173 // somewhere else. If somebody wants two string tables in their .s file, one
174 // will just be empty.
175 if (!InsertedStrTabFragment) {
176 OS.insert(getStringTableFragment());
177 InsertedStrTabFragment = true;
180 OS.EmitValueToAlignment(4, 0);
182 OS.EmitLabel(StringEnd);
185 void CodeViewContext::emitFileChecksums(MCObjectStreamer &OS) {
186 // Do nothing if there are no file checksums. Microsoft's linker rejects empty
187 // CodeView substreams.
191 MCContext &Ctx = OS.getContext();
192 MCSymbol *FileBegin = Ctx.createTempSymbol("filechecksums_begin", false),
193 *FileEnd = Ctx.createTempSymbol("filechecksums_end", false);
195 OS.EmitIntValue(unsigned(DebugSubsectionKind::FileChecksums), 4);
196 OS.emitAbsoluteSymbolDiff(FileEnd, FileBegin, 4);
197 OS.EmitLabel(FileBegin);
199 unsigned CurrentOffset = 0;
201 // Emit an array of FileChecksum entries. We index into this table using the
202 // user-provided file number. Each entry may be a variable number of bytes
203 // determined by the checksum kind and size.
204 for (auto File : Files) {
205 OS.EmitAssignment(File.ChecksumTableOffset,
206 MCConstantExpr::create(CurrentOffset, Ctx));
207 CurrentOffset += 4; // String table offset.
208 if (!File.ChecksumKind) {
210 4; // One byte each for checksum size and kind, then align to 4 bytes.
212 CurrentOffset += 2; // One byte each for checksum size and kind.
213 CurrentOffset += File.Checksum.size();
214 CurrentOffset = alignTo(CurrentOffset, 4);
217 OS.EmitIntValue(File.StringTableOffset, 4);
219 if (!File.ChecksumKind) {
220 // There is no checksum. Therefore zero the next two fields and align
222 OS.EmitIntValue(0, 4);
225 OS.EmitIntValue(static_cast<uint8_t>(File.Checksum.size()), 1);
226 OS.EmitIntValue(File.ChecksumKind, 1);
227 OS.EmitBytes(toStringRef(File.Checksum));
228 OS.EmitValueToAlignment(4);
231 OS.EmitLabel(FileEnd);
233 ChecksumOffsetsAssigned = true;
236 // Output checksum table offset of the given file number. It is possible that
237 // not all files have been registered yet, and so the offset cannot be
238 // calculated. In this case a symbol representing the offset is emitted, and
239 // the value of this symbol will be fixed up at a later time.
240 void CodeViewContext::emitFileChecksumOffset(MCObjectStreamer &OS,
242 unsigned Idx = FileNo - 1;
244 if (Idx >= Files.size())
245 Files.resize(Idx + 1);
247 if (ChecksumOffsetsAssigned) {
248 OS.EmitSymbolValue(Files[Idx].ChecksumTableOffset, 4);
252 const MCSymbolRefExpr *SRE =
253 MCSymbolRefExpr::create(Files[Idx].ChecksumTableOffset, OS.getContext());
255 OS.EmitValueImpl(SRE, 4);
258 void CodeViewContext::addLineEntry(const MCCVLineEntry &LineEntry) {
259 size_t Offset = MCCVLines.size();
260 auto I = MCCVLineStartStop.insert(
261 {LineEntry.getFunctionId(), {Offset, Offset + 1}});
263 I.first->second.second = Offset + 1;
264 MCCVLines.push_back(LineEntry);
267 std::vector<MCCVLineEntry>
268 CodeViewContext::getFunctionLineEntries(unsigned FuncId) {
269 std::vector<MCCVLineEntry> FilteredLines;
270 auto I = MCCVLineStartStop.find(FuncId);
271 if (I != MCCVLineStartStop.end()) {
272 MCCVFunctionInfo *SiteInfo = getCVFunctionInfo(FuncId);
273 for (size_t Idx = I->second.first, End = I->second.second; Idx != End;
275 unsigned LocationFuncId = MCCVLines[Idx].getFunctionId();
276 if (LocationFuncId == FuncId) {
277 // This was a .cv_loc directly for FuncId, so record it.
278 FilteredLines.push_back(MCCVLines[Idx]);
280 // Check if the current location is inlined in this function. If it is,
281 // synthesize a statement .cv_loc at the original inlined call site.
282 auto I = SiteInfo->InlinedAtMap.find(LocationFuncId);
283 if (I != SiteInfo->InlinedAtMap.end()) {
284 MCCVFunctionInfo::LineInfo &IA = I->second;
285 // Only add the location if it differs from the previous location.
286 // Large inlined calls will have many .cv_loc entries and we only need
287 // one line table entry in the parent function.
288 if (FilteredLines.empty() ||
289 FilteredLines.back().getFileNum() != IA.File ||
290 FilteredLines.back().getLine() != IA.Line ||
291 FilteredLines.back().getColumn() != IA.Col) {
292 FilteredLines.push_back(MCCVLineEntry(
293 MCCVLines[Idx].getLabel(),
294 MCCVLoc(FuncId, IA.File, IA.Line, IA.Col, false, false)));
300 return FilteredLines;
303 std::pair<size_t, size_t> CodeViewContext::getLineExtent(unsigned FuncId) {
304 auto I = MCCVLineStartStop.find(FuncId);
305 // Return an empty extent if there are no cv_locs for this function id.
306 if (I == MCCVLineStartStop.end())
311 ArrayRef<MCCVLineEntry> CodeViewContext::getLinesForExtent(size_t L, size_t R) {
314 if (L >= MCCVLines.size())
316 return makeArrayRef(&MCCVLines[L], R - L);
319 void CodeViewContext::emitLineTableForFunction(MCObjectStreamer &OS,
321 const MCSymbol *FuncBegin,
322 const MCSymbol *FuncEnd) {
323 MCContext &Ctx = OS.getContext();
324 MCSymbol *LineBegin = Ctx.createTempSymbol("linetable_begin", false),
325 *LineEnd = Ctx.createTempSymbol("linetable_end", false);
327 OS.EmitIntValue(unsigned(DebugSubsectionKind::Lines), 4);
328 OS.emitAbsoluteSymbolDiff(LineEnd, LineBegin, 4);
329 OS.EmitLabel(LineBegin);
330 OS.EmitCOFFSecRel32(FuncBegin, /*Offset=*/0);
331 OS.EmitCOFFSectionIndex(FuncBegin);
334 std::vector<MCCVLineEntry> Locs = getFunctionLineEntries(FuncId);
335 bool HaveColumns = any_of(Locs, [](const MCCVLineEntry &LineEntry) {
336 return LineEntry.getColumn() != 0;
338 OS.EmitIntValue(HaveColumns ? int(LF_HaveColumns) : 0, 2);
339 OS.emitAbsoluteSymbolDiff(FuncEnd, FuncBegin, 4);
341 for (auto I = Locs.begin(), E = Locs.end(); I != E;) {
342 // Emit a file segment for the run of locations that share a file id.
343 unsigned CurFileNum = I->getFileNum();
345 std::find_if(I, E, [CurFileNum](const MCCVLineEntry &Loc) {
346 return Loc.getFileNum() != CurFileNum;
348 unsigned EntryCount = FileSegEnd - I;
350 "Segment for file '" +
351 Twine(getStringTableFragment()
352 ->getContents()[Files[CurFileNum - 1].StringTableOffset]) +
354 OS.EmitCVFileChecksumOffsetDirective(CurFileNum);
355 OS.EmitIntValue(EntryCount, 4);
356 uint32_t SegmentSize = 12;
357 SegmentSize += 8 * EntryCount;
359 SegmentSize += 4 * EntryCount;
360 OS.EmitIntValue(SegmentSize, 4);
362 for (auto J = I; J != FileSegEnd; ++J) {
363 OS.emitAbsoluteSymbolDiff(J->getLabel(), FuncBegin, 4);
364 unsigned LineData = J->getLine();
366 LineData |= LineInfo::StatementFlag;
367 OS.EmitIntValue(LineData, 4);
370 for (auto J = I; J != FileSegEnd; ++J) {
371 OS.EmitIntValue(J->getColumn(), 2);
372 OS.EmitIntValue(0, 2);
377 OS.EmitLabel(LineEnd);
380 static bool compressAnnotation(uint32_t Data, SmallVectorImpl<char> &Buffer) {
381 if (isUInt<7>(Data)) {
382 Buffer.push_back(Data);
386 if (isUInt<14>(Data)) {
387 Buffer.push_back((Data >> 8) | 0x80);
388 Buffer.push_back(Data & 0xff);
392 if (isUInt<29>(Data)) {
393 Buffer.push_back((Data >> 24) | 0xC0);
394 Buffer.push_back((Data >> 16) & 0xff);
395 Buffer.push_back((Data >> 8) & 0xff);
396 Buffer.push_back(Data & 0xff);
403 static bool compressAnnotation(BinaryAnnotationsOpCode Annotation,
404 SmallVectorImpl<char> &Buffer) {
405 return compressAnnotation(static_cast<uint32_t>(Annotation), Buffer);
408 static uint32_t encodeSignedNumber(uint32_t Data) {
410 return ((-Data) << 1) | 1;
414 void CodeViewContext::emitInlineLineTableForFunction(MCObjectStreamer &OS,
415 unsigned PrimaryFunctionId,
416 unsigned SourceFileId,
417 unsigned SourceLineNum,
418 const MCSymbol *FnStartSym,
419 const MCSymbol *FnEndSym) {
420 // Create and insert a fragment into the current section that will be encoded
422 new MCCVInlineLineTableFragment(PrimaryFunctionId, SourceFileId,
423 SourceLineNum, FnStartSym, FnEndSym,
424 OS.getCurrentSectionOnly());
427 void CodeViewContext::emitDefRange(
428 MCObjectStreamer &OS,
429 ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
430 StringRef FixedSizePortion) {
431 // Create and insert a fragment into the current section that will be encoded
433 new MCCVDefRangeFragment(Ranges, FixedSizePortion,
434 OS.getCurrentSectionOnly());
437 static unsigned computeLabelDiff(MCAsmLayout &Layout, const MCSymbol *Begin,
438 const MCSymbol *End) {
439 MCContext &Ctx = Layout.getAssembler().getContext();
440 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
441 const MCExpr *BeginRef = MCSymbolRefExpr::create(Begin, Variant, Ctx),
442 *EndRef = MCSymbolRefExpr::create(End, Variant, Ctx);
443 const MCExpr *AddrDelta =
444 MCBinaryExpr::create(MCBinaryExpr::Sub, EndRef, BeginRef, Ctx);
446 bool Success = AddrDelta->evaluateKnownAbsolute(Result, Layout);
447 assert(Success && "failed to evaluate label difference as absolute");
449 assert(Result >= 0 && "negative label difference requested");
450 assert(Result < UINT_MAX && "label difference greater than 2GB");
451 return unsigned(Result);
454 void CodeViewContext::encodeInlineLineTable(MCAsmLayout &Layout,
455 MCCVInlineLineTableFragment &Frag) {
458 std::tie(LocBegin, LocEnd) = getLineExtent(Frag.SiteFuncId);
460 // Include all child inline call sites in our .cv_loc extent.
461 MCCVFunctionInfo *SiteInfo = getCVFunctionInfo(Frag.SiteFuncId);
462 for (auto &KV : SiteInfo->InlinedAtMap) {
463 unsigned ChildId = KV.first;
464 auto Extent = getLineExtent(ChildId);
465 LocBegin = std::min(LocBegin, Extent.first);
466 LocEnd = std::max(LocEnd, Extent.second);
469 if (LocBegin >= LocEnd)
471 ArrayRef<MCCVLineEntry> Locs = getLinesForExtent(LocBegin, LocEnd);
475 // Make an artificial start location using the function start and the inlinee
476 // lines start location information. All deltas start relative to this
478 MCCVLineEntry StartLoc(Frag.getFnStartSym(), MCCVLoc(Locs.front()));
479 StartLoc.setFileNum(Frag.StartFileId);
480 StartLoc.setLine(Frag.StartLineNum);
481 bool HaveOpenRange = false;
483 const MCSymbol *LastLabel = Frag.getFnStartSym();
484 MCCVFunctionInfo::LineInfo LastSourceLoc, CurSourceLoc;
485 LastSourceLoc.File = Frag.StartFileId;
486 LastSourceLoc.Line = Frag.StartLineNum;
488 SmallVectorImpl<char> &Buffer = Frag.getContents();
489 Buffer.clear(); // Clear old contents if we went through relaxation.
490 for (const MCCVLineEntry &Loc : Locs) {
491 // Exit early if our line table would produce an oversized InlineSiteSym
492 // record. Account for the ChangeCodeLength annotation emitted after the
494 constexpr uint32_t InlineSiteSize = 12;
495 constexpr uint32_t AnnotationSize = 8;
496 size_t MaxBufferSize = MaxRecordLength - InlineSiteSize - AnnotationSize;
497 if (Buffer.size() >= MaxBufferSize)
500 if (Loc.getFunctionId() == Frag.SiteFuncId) {
501 CurSourceLoc.File = Loc.getFileNum();
502 CurSourceLoc.Line = Loc.getLine();
504 auto I = SiteInfo->InlinedAtMap.find(Loc.getFunctionId());
505 if (I != SiteInfo->InlinedAtMap.end()) {
506 // This .cv_loc is from a child inline call site. Use the source
507 // location of the inlined call site instead of the .cv_loc directive
509 CurSourceLoc = I->second;
511 // We've hit a cv_loc not attributed to this inline call site. Use this
512 // label to end the PC range.
514 unsigned Length = computeLabelDiff(Layout, LastLabel, Loc.getLabel());
515 compressAnnotation(BinaryAnnotationsOpCode::ChangeCodeLength, Buffer);
516 compressAnnotation(Length, Buffer);
517 LastLabel = Loc.getLabel();
519 HaveOpenRange = false;
524 // Skip this .cv_loc if we have an open range and this isn't a meaningful
525 // source location update. The current table format does not support column
526 // info, so we can skip updates for those.
527 if (HaveOpenRange && CurSourceLoc.File == LastSourceLoc.File &&
528 CurSourceLoc.Line == LastSourceLoc.Line)
531 HaveOpenRange = true;
533 if (CurSourceLoc.File != LastSourceLoc.File) {
534 unsigned FileOffset = static_cast<const MCConstantExpr *>(
535 Files[CurSourceLoc.File - 1]
536 .ChecksumTableOffset->getVariableValue())
538 compressAnnotation(BinaryAnnotationsOpCode::ChangeFile, Buffer);
539 compressAnnotation(FileOffset, Buffer);
542 int LineDelta = CurSourceLoc.Line - LastSourceLoc.Line;
543 unsigned EncodedLineDelta = encodeSignedNumber(LineDelta);
544 unsigned CodeDelta = computeLabelDiff(Layout, LastLabel, Loc.getLabel());
545 if (CodeDelta == 0 && LineDelta != 0) {
546 compressAnnotation(BinaryAnnotationsOpCode::ChangeLineOffset, Buffer);
547 compressAnnotation(EncodedLineDelta, Buffer);
548 } else if (EncodedLineDelta < 0x8 && CodeDelta <= 0xf) {
549 // The ChangeCodeOffsetAndLineOffset combination opcode is used when the
550 // encoded line delta uses 3 or fewer set bits and the code offset fits
552 unsigned Operand = (EncodedLineDelta << 4) | CodeDelta;
553 compressAnnotation(BinaryAnnotationsOpCode::ChangeCodeOffsetAndLineOffset,
555 compressAnnotation(Operand, Buffer);
557 // Otherwise use the separate line and code deltas.
558 if (LineDelta != 0) {
559 compressAnnotation(BinaryAnnotationsOpCode::ChangeLineOffset, Buffer);
560 compressAnnotation(EncodedLineDelta, Buffer);
562 compressAnnotation(BinaryAnnotationsOpCode::ChangeCodeOffset, Buffer);
563 compressAnnotation(CodeDelta, Buffer);
566 LastLabel = Loc.getLabel();
567 LastSourceLoc = CurSourceLoc;
570 assert(HaveOpenRange);
572 unsigned EndSymLength =
573 computeLabelDiff(Layout, LastLabel, Frag.getFnEndSym());
574 unsigned LocAfterLength = ~0U;
575 ArrayRef<MCCVLineEntry> LocAfter = getLinesForExtent(LocEnd, LocEnd + 1);
576 if (!LocAfter.empty()) {
577 // Only try to compute this difference if we're in the same section.
578 const MCCVLineEntry &Loc = LocAfter[0];
579 if (&Loc.getLabel()->getSection(false) == &LastLabel->getSection(false))
580 LocAfterLength = computeLabelDiff(Layout, LastLabel, Loc.getLabel());
583 compressAnnotation(BinaryAnnotationsOpCode::ChangeCodeLength, Buffer);
584 compressAnnotation(std::min(EndSymLength, LocAfterLength), Buffer);
587 void CodeViewContext::encodeDefRange(MCAsmLayout &Layout,
588 MCCVDefRangeFragment &Frag) {
589 MCContext &Ctx = Layout.getAssembler().getContext();
590 SmallVectorImpl<char> &Contents = Frag.getContents();
592 SmallVectorImpl<MCFixup> &Fixups = Frag.getFixups();
594 raw_svector_ostream OS(Contents);
596 // Compute all the sizes up front.
597 SmallVector<std::pair<unsigned, unsigned>, 4> GapAndRangeSizes;
598 const MCSymbol *LastLabel = nullptr;
599 for (std::pair<const MCSymbol *, const MCSymbol *> Range : Frag.getRanges()) {
601 LastLabel ? computeLabelDiff(Layout, LastLabel, Range.first) : 0;
602 unsigned RangeSize = computeLabelDiff(Layout, Range.first, Range.second);
603 GapAndRangeSizes.push_back({GapSize, RangeSize});
604 LastLabel = Range.second;
607 // Write down each range where the variable is defined.
608 for (size_t I = 0, E = Frag.getRanges().size(); I != E;) {
609 // If the range size of multiple consecutive ranges is under the max,
610 // combine the ranges and emit some gaps.
611 const MCSymbol *RangeBegin = Frag.getRanges()[I].first;
612 unsigned RangeSize = GapAndRangeSizes[I].second;
614 for (; J != E; ++J) {
615 unsigned GapAndRangeSize = GapAndRangeSizes[J].first + GapAndRangeSizes[J].second;
616 if (RangeSize + GapAndRangeSize > MaxDefRange)
618 RangeSize += GapAndRangeSize;
620 unsigned NumGaps = J - I - 1;
622 support::endian::Writer<support::little> LEWriter(OS);
625 // We must split the range into chunks of MaxDefRange, this is a fundamental
626 // limitation of the file format.
628 uint16_t Chunk = std::min((uint32_t)MaxDefRange, RangeSize);
630 const MCSymbolRefExpr *SRE = MCSymbolRefExpr::create(RangeBegin, Ctx);
631 const MCBinaryExpr *BE =
632 MCBinaryExpr::createAdd(SRE, MCConstantExpr::create(Bias, Ctx), Ctx);
634 BE->evaluateAsRelocatable(Res, &Layout, /*Fixup=*/nullptr);
636 // Each record begins with a 2-byte number indicating how large the record
638 StringRef FixedSizePortion = Frag.getFixedSizePortion();
639 // Our record is a fixed sized prefix and a LocalVariableAddrRange that we
640 // are artificially constructing.
641 size_t RecordSize = FixedSizePortion.size() +
642 sizeof(LocalVariableAddrRange) + 4 * NumGaps;
643 // Write out the record size.
644 LEWriter.write<uint16_t>(RecordSize);
645 // Write out the fixed size prefix.
646 OS << FixedSizePortion;
647 // Make space for a fixup that will eventually have a section relative
648 // relocation pointing at the offset where the variable becomes live.
649 Fixups.push_back(MCFixup::create(Contents.size(), BE, FK_SecRel_4));
650 LEWriter.write<uint32_t>(0); // Fixup for code start.
651 // Make space for a fixup that will record the section index for the code.
652 Fixups.push_back(MCFixup::create(Contents.size(), BE, FK_SecRel_2));
653 LEWriter.write<uint16_t>(0); // Fixup for section index.
654 // Write down the range's extent.
655 LEWriter.write<uint16_t>(Chunk);
657 // Move on to the next range.
660 } while (RangeSize > 0);
662 // Emit the gaps afterwards.
663 assert((NumGaps == 0 || Bias <= MaxDefRange) &&
664 "large ranges should not have gaps");
665 unsigned GapStartOffset = GapAndRangeSizes[I].second;
666 for (++I; I != J; ++I) {
667 unsigned GapSize, RangeSize;
668 assert(I < GapAndRangeSizes.size());
669 std::tie(GapSize, RangeSize) = GapAndRangeSizes[I];
670 LEWriter.write<uint16_t>(GapStartOffset);
671 LEWriter.write<uint16_t>(GapSize);
672 GapStartOffset += GapSize + RangeSize;
678 // This is called when an instruction is assembled into the specified section
679 // and if there is information from the last .cv_loc directive that has yet to have
680 // a line entry made for it is made.
682 void MCCVLineEntry::Make(MCObjectStreamer *MCOS) {
683 CodeViewContext &CVC = MCOS->getContext().getCVContext();
684 if (!CVC.getCVLocSeen())
687 // Create a symbol at in the current section for use in the line entry.
688 MCSymbol *LineSym = MCOS->getContext().createTempSymbol();
689 // Set the value of the symbol to use for the MCCVLineEntry.
690 MCOS->EmitLabel(LineSym);
692 // Get the current .loc info saved in the context.
693 const MCCVLoc &CVLoc = CVC.getCurrentCVLoc();
695 // Create a (local) line entry with the symbol and the current .loc info.
696 MCCVLineEntry LineEntry(LineSym, CVLoc);
698 // clear CVLocSeen saying the current .loc info is now used.
699 CVC.clearCVLocSeen();
701 // Add the line entry to this section's entries.
702 CVC.addLineEntry(LineEntry);