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llvm-mirror/lib/MC/MCCodeView.cpp
Reid Kleckner bcdfe567cb [CodeView] Add line numbers for inlined call sites 
We did this for inline call site line tables, but we hadn't done it for
regular function line tables yet. This patch copies that logic from
encodeInlineLineTable.

llvm-svn: 322905
2018-01-18 22:55:43 +00:00

704 lines
26 KiB
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//===- MCCodeView.h - Machine Code CodeView support -------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Holds state from .cv_file and .cv_loc directives for later emission.
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCCodeView.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/DebugInfo/CodeView/CodeView.h"
#include "llvm/DebugInfo/CodeView/Line.h"
#include "llvm/DebugInfo/CodeView/SymbolRecord.h"
#include "llvm/MC/MCAsmLayout.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCObjectStreamer.h"
#include "llvm/MC/MCValue.h"
#include "llvm/Support/EndianStream.h"
using namespace llvm;
using namespace llvm::codeview;
CodeViewContext::CodeViewContext() {}
CodeViewContext::~CodeViewContext() {
// If someone inserted strings into the string table but never actually
// emitted them somewhere, clean up the fragment.
if (!InsertedStrTabFragment)
delete StrTabFragment;
}
/// This is a valid number for use with .cv_loc if we've already seen a .cv_file
/// for it.
bool CodeViewContext::isValidFileNumber(unsigned FileNumber) const {
unsigned Idx = FileNumber - 1;
if (Idx < Files.size())
return Files[Idx].Assigned;
return false;
}
bool CodeViewContext::addFile(MCStreamer &OS, unsigned FileNumber,
StringRef Filename,
ArrayRef<uint8_t> ChecksumBytes,
uint8_t ChecksumKind) {
assert(FileNumber > 0);
auto FilenameOffset = addToStringTable(Filename);
Filename = FilenameOffset.first;
unsigned Idx = FileNumber - 1;
if (Idx >= Files.size())
Files.resize(Idx + 1);
if (Filename.empty())
Filename = "<stdin>";
if (Files[Idx].Assigned)
return false;
FilenameOffset = addToStringTable(Filename);
Filename = FilenameOffset.first;
unsigned Offset = FilenameOffset.second;
auto ChecksumOffsetSymbol =
OS.getContext().createTempSymbol("checksum_offset", false);
Files[Idx].StringTableOffset = Offset;
Files[Idx].ChecksumTableOffset = ChecksumOffsetSymbol;
Files[Idx].Assigned = true;
Files[Idx].Checksum = ChecksumBytes;
Files[Idx].ChecksumKind = ChecksumKind;
return true;
}
MCCVFunctionInfo *CodeViewContext::getCVFunctionInfo(unsigned FuncId) {
if (FuncId >= Functions.size())
return nullptr;
if (Functions[FuncId].isUnallocatedFunctionInfo())
return nullptr;
return &Functions[FuncId];
}
bool CodeViewContext::recordFunctionId(unsigned FuncId) {
if (FuncId >= Functions.size())
Functions.resize(FuncId + 1);
// Return false if this function info was already allocated.
if (!Functions[FuncId].isUnallocatedFunctionInfo())
return false;
// Mark this as an allocated normal function, and leave the rest alone.
Functions[FuncId].ParentFuncIdPlusOne = MCCVFunctionInfo::FunctionSentinel;
return true;
}
bool CodeViewContext::recordInlinedCallSiteId(unsigned FuncId, unsigned IAFunc,
unsigned IAFile, unsigned IALine,
unsigned IACol) {
if (FuncId >= Functions.size())
Functions.resize(FuncId + 1);
// Return false if this function info was already allocated.
if (!Functions[FuncId].isUnallocatedFunctionInfo())
return false;
MCCVFunctionInfo::LineInfo InlinedAt;
InlinedAt.File = IAFile;
InlinedAt.Line = IALine;
InlinedAt.Col = IACol;
// Mark this as an inlined call site and record call site line info.
MCCVFunctionInfo *Info = &Functions[FuncId];
Info->ParentFuncIdPlusOne = IAFunc + 1;
Info->InlinedAt = InlinedAt;
// Walk up the call chain adding this function id to the InlinedAtMap of all
// transitive callers until we hit a real function.
while (Info->isInlinedCallSite()) {
InlinedAt = Info->InlinedAt;
Info = getCVFunctionInfo(Info->getParentFuncId());
Info->InlinedAtMap[FuncId] = InlinedAt;
}
return true;
}
MCDataFragment *CodeViewContext::getStringTableFragment() {
if (!StrTabFragment) {
StrTabFragment = new MCDataFragment();
// Start a new string table out with a null byte.
StrTabFragment->getContents().push_back('\0');
}
return StrTabFragment;
}
std::pair<StringRef, unsigned> CodeViewContext::addToStringTable(StringRef S) {
SmallVectorImpl<char> &Contents = getStringTableFragment()->getContents();
auto Insertion =
StringTable.insert(std::make_pair(S, unsigned(Contents.size())));
// Return the string from the table, since it is stable.
std::pair<StringRef, unsigned> Ret =
std::make_pair(Insertion.first->first(), Insertion.first->second);
if (Insertion.second) {
// The string map key is always null terminated.
Contents.append(Ret.first.begin(), Ret.first.end() + 1);
}
return Ret;
}
unsigned CodeViewContext::getStringTableOffset(StringRef S) {
// A string table offset of zero is always the empty string.
if (S.empty())
return 0;
auto I = StringTable.find(S);
assert(I != StringTable.end());
return I->second;
}
void CodeViewContext::emitStringTable(MCObjectStreamer &OS) {
MCContext &Ctx = OS.getContext();
MCSymbol *StringBegin = Ctx.createTempSymbol("strtab_begin", false),
*StringEnd = Ctx.createTempSymbol("strtab_end", false);
OS.EmitIntValue(unsigned(DebugSubsectionKind::StringTable), 4);
OS.emitAbsoluteSymbolDiff(StringEnd, StringBegin, 4);
OS.EmitLabel(StringBegin);
// Put the string table data fragment here, if we haven't already put it
// somewhere else. If somebody wants two string tables in their .s file, one
// will just be empty.
if (!InsertedStrTabFragment) {
OS.insert(getStringTableFragment());
InsertedStrTabFragment = true;
}
OS.EmitValueToAlignment(4, 0);
OS.EmitLabel(StringEnd);
}
void CodeViewContext::emitFileChecksums(MCObjectStreamer &OS) {
// Do nothing if there are no file checksums. Microsoft's linker rejects empty
// CodeView substreams.
if (Files.empty())
return;
MCContext &Ctx = OS.getContext();
MCSymbol *FileBegin = Ctx.createTempSymbol("filechecksums_begin", false),
*FileEnd = Ctx.createTempSymbol("filechecksums_end", false);
OS.EmitIntValue(unsigned(DebugSubsectionKind::FileChecksums), 4);
OS.emitAbsoluteSymbolDiff(FileEnd, FileBegin, 4);
OS.EmitLabel(FileBegin);
unsigned CurrentOffset = 0;
// Emit an array of FileChecksum entries. We index into this table using the
// user-provided file number. Each entry may be a variable number of bytes
// determined by the checksum kind and size.
for (auto File : Files) {
OS.EmitAssignment(File.ChecksumTableOffset,
MCConstantExpr::create(CurrentOffset, Ctx));
CurrentOffset += 4; // String table offset.
if (!File.ChecksumKind) {
CurrentOffset +=
4; // One byte each for checksum size and kind, then align to 4 bytes.
} else {
CurrentOffset += 2; // One byte each for checksum size and kind.
CurrentOffset += File.Checksum.size();
CurrentOffset = alignTo(CurrentOffset, 4);
}
OS.EmitIntValue(File.StringTableOffset, 4);
if (!File.ChecksumKind) {
// There is no checksum. Therefore zero the next two fields and align
// back to 4 bytes.
OS.EmitIntValue(0, 4);
continue;
}
OS.EmitIntValue(static_cast<uint8_t>(File.Checksum.size()), 1);
OS.EmitIntValue(File.ChecksumKind, 1);
OS.EmitBytes(toStringRef(File.Checksum));
OS.EmitValueToAlignment(4);
}
OS.EmitLabel(FileEnd);
ChecksumOffsetsAssigned = true;
}
// Output checksum table offset of the given file number. It is possible that
// not all files have been registered yet, and so the offset cannot be
// calculated. In this case a symbol representing the offset is emitted, and
// the value of this symbol will be fixed up at a later time.
void CodeViewContext::emitFileChecksumOffset(MCObjectStreamer &OS,
unsigned FileNo) {
unsigned Idx = FileNo - 1;
if (Idx >= Files.size())
Files.resize(Idx + 1);
if (ChecksumOffsetsAssigned) {
OS.EmitSymbolValue(Files[Idx].ChecksumTableOffset, 4);
return;
}
const MCSymbolRefExpr *SRE =
MCSymbolRefExpr::create(Files[Idx].ChecksumTableOffset, OS.getContext());
OS.EmitValueImpl(SRE, 4);
}
void CodeViewContext::addLineEntry(const MCCVLineEntry &LineEntry) {
size_t Offset = MCCVLines.size();
auto I = MCCVLineStartStop.insert(
{LineEntry.getFunctionId(), {Offset, Offset + 1}});
if (!I.second)
I.first->second.second = Offset + 1;
MCCVLines.push_back(LineEntry);
}
std::vector<MCCVLineEntry>
CodeViewContext::getFunctionLineEntries(unsigned FuncId) {
std::vector<MCCVLineEntry> FilteredLines;
auto I = MCCVLineStartStop.find(FuncId);
if (I != MCCVLineStartStop.end()) {
MCCVFunctionInfo *SiteInfo = getCVFunctionInfo(FuncId);
for (size_t Idx = I->second.first, End = I->second.second; Idx != End;
++Idx) {
unsigned LocationFuncId = MCCVLines[Idx].getFunctionId();
if (LocationFuncId == FuncId) {
// This was a .cv_loc directly for FuncId, so record it.
FilteredLines.push_back(MCCVLines[Idx]);
} else {
// Check if the current location is inlined in this function. If it is,
// synthesize a statement .cv_loc at the original inlined call site.
auto I = SiteInfo->InlinedAtMap.find(LocationFuncId);
if (I != SiteInfo->InlinedAtMap.end()) {
MCCVFunctionInfo::LineInfo &IA = I->second;
// Only add the location if it differs from the previous location.
// Large inlined calls will have many .cv_loc entries and we only need
// one line table entry in the parent function.
if (FilteredLines.empty() ||
FilteredLines.back().getFileNum() != IA.File ||
FilteredLines.back().getLine() != IA.Line ||
FilteredLines.back().getColumn() != IA.Col) {
FilteredLines.push_back(MCCVLineEntry(
MCCVLines[Idx].getLabel(),
MCCVLoc(FuncId, IA.File, IA.Line, IA.Col, false, false)));
}
}
}
}
}
return FilteredLines;
}
std::pair<size_t, size_t> CodeViewContext::getLineExtent(unsigned FuncId) {
auto I = MCCVLineStartStop.find(FuncId);
// Return an empty extent if there are no cv_locs for this function id.
if (I == MCCVLineStartStop.end())
return {~0ULL, 0};
return I->second;
}
ArrayRef<MCCVLineEntry> CodeViewContext::getLinesForExtent(size_t L, size_t R) {
if (R <= L)
return None;
if (L >= MCCVLines.size())
return None;
return makeArrayRef(&MCCVLines[L], R - L);
}
void CodeViewContext::emitLineTableForFunction(MCObjectStreamer &OS,
unsigned FuncId,
const MCSymbol *FuncBegin,
const MCSymbol *FuncEnd) {
MCContext &Ctx = OS.getContext();
MCSymbol *LineBegin = Ctx.createTempSymbol("linetable_begin", false),
*LineEnd = Ctx.createTempSymbol("linetable_end", false);
OS.EmitIntValue(unsigned(DebugSubsectionKind::Lines), 4);
OS.emitAbsoluteSymbolDiff(LineEnd, LineBegin, 4);
OS.EmitLabel(LineBegin);
OS.EmitCOFFSecRel32(FuncBegin, /*Offset=*/0);
OS.EmitCOFFSectionIndex(FuncBegin);
// Actual line info.
std::vector<MCCVLineEntry> Locs = getFunctionLineEntries(FuncId);
bool HaveColumns = any_of(Locs, [](const MCCVLineEntry &LineEntry) {
return LineEntry.getColumn() != 0;
});
OS.EmitIntValue(HaveColumns ? int(LF_HaveColumns) : 0, 2);
OS.emitAbsoluteSymbolDiff(FuncEnd, FuncBegin, 4);
for (auto I = Locs.begin(), E = Locs.end(); I != E;) {
// Emit a file segment for the run of locations that share a file id.
unsigned CurFileNum = I->getFileNum();
auto FileSegEnd =
std::find_if(I, E, [CurFileNum](const MCCVLineEntry &Loc) {
return Loc.getFileNum() != CurFileNum;
});
unsigned EntryCount = FileSegEnd - I;
OS.AddComment(
"Segment for file '" +
Twine(getStringTableFragment()
->getContents()[Files[CurFileNum - 1].StringTableOffset]) +
"' begins");
OS.EmitCVFileChecksumOffsetDirective(CurFileNum);
OS.EmitIntValue(EntryCount, 4);
uint32_t SegmentSize = 12;
SegmentSize += 8 * EntryCount;
if (HaveColumns)
SegmentSize += 4 * EntryCount;
OS.EmitIntValue(SegmentSize, 4);
for (auto J = I; J != FileSegEnd; ++J) {
OS.emitAbsoluteSymbolDiff(J->getLabel(), FuncBegin, 4);
unsigned LineData = J->getLine();
if (J->isStmt())
LineData |= LineInfo::StatementFlag;
OS.EmitIntValue(LineData, 4);
}
if (HaveColumns) {
for (auto J = I; J != FileSegEnd; ++J) {
OS.EmitIntValue(J->getColumn(), 2);
OS.EmitIntValue(0, 2);
}
}
I = FileSegEnd;
}
OS.EmitLabel(LineEnd);
}
static bool compressAnnotation(uint32_t Data, SmallVectorImpl<char> &Buffer) {
if (isUInt<7>(Data)) {
Buffer.push_back(Data);
return true;
}
if (isUInt<14>(Data)) {
Buffer.push_back((Data >> 8) | 0x80);
Buffer.push_back(Data & 0xff);
return true;
}
if (isUInt<29>(Data)) {
Buffer.push_back((Data >> 24) | 0xC0);
Buffer.push_back((Data >> 16) & 0xff);
Buffer.push_back((Data >> 8) & 0xff);
Buffer.push_back(Data & 0xff);
return true;
}
return false;
}
static bool compressAnnotation(BinaryAnnotationsOpCode Annotation,
SmallVectorImpl<char> &Buffer) {
return compressAnnotation(static_cast<uint32_t>(Annotation), Buffer);
}
static uint32_t encodeSignedNumber(uint32_t Data) {
if (Data >> 31)
return ((-Data) << 1) | 1;
return Data << 1;
}
void CodeViewContext::emitInlineLineTableForFunction(MCObjectStreamer &OS,
unsigned PrimaryFunctionId,
unsigned SourceFileId,
unsigned SourceLineNum,
const MCSymbol *FnStartSym,
const MCSymbol *FnEndSym) {
// Create and insert a fragment into the current section that will be encoded
// later.
new MCCVInlineLineTableFragment(PrimaryFunctionId, SourceFileId,
SourceLineNum, FnStartSym, FnEndSym,
OS.getCurrentSectionOnly());
}
void CodeViewContext::emitDefRange(
MCObjectStreamer &OS,
ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
StringRef FixedSizePortion) {
// Create and insert a fragment into the current section that will be encoded
// later.
new MCCVDefRangeFragment(Ranges, FixedSizePortion,
OS.getCurrentSectionOnly());
}
static unsigned computeLabelDiff(MCAsmLayout &Layout, const MCSymbol *Begin,
const MCSymbol *End) {
MCContext &Ctx = Layout.getAssembler().getContext();
MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
const MCExpr *BeginRef = MCSymbolRefExpr::create(Begin, Variant, Ctx),
*EndRef = MCSymbolRefExpr::create(End, Variant, Ctx);
const MCExpr *AddrDelta =
MCBinaryExpr::create(MCBinaryExpr::Sub, EndRef, BeginRef, Ctx);
int64_t Result;
bool Success = AddrDelta->evaluateKnownAbsolute(Result, Layout);
assert(Success && "failed to evaluate label difference as absolute");
(void)Success;
assert(Result >= 0 && "negative label difference requested");
assert(Result < UINT_MAX && "label difference greater than 2GB");
return unsigned(Result);
}
void CodeViewContext::encodeInlineLineTable(MCAsmLayout &Layout,
MCCVInlineLineTableFragment &Frag) {
size_t LocBegin;
size_t LocEnd;
std::tie(LocBegin, LocEnd) = getLineExtent(Frag.SiteFuncId);
// Include all child inline call sites in our .cv_loc extent.
MCCVFunctionInfo *SiteInfo = getCVFunctionInfo(Frag.SiteFuncId);
for (auto &KV : SiteInfo->InlinedAtMap) {
unsigned ChildId = KV.first;
auto Extent = getLineExtent(ChildId);
LocBegin = std::min(LocBegin, Extent.first);
LocEnd = std::max(LocEnd, Extent.second);
}
if (LocBegin >= LocEnd)
return;
ArrayRef<MCCVLineEntry> Locs = getLinesForExtent(LocBegin, LocEnd);
if (Locs.empty())
return;
// Make an artificial start location using the function start and the inlinee
// lines start location information. All deltas start relative to this
// location.
MCCVLineEntry StartLoc(Frag.getFnStartSym(), MCCVLoc(Locs.front()));
StartLoc.setFileNum(Frag.StartFileId);
StartLoc.setLine(Frag.StartLineNum);
bool HaveOpenRange = false;
const MCSymbol *LastLabel = Frag.getFnStartSym();
MCCVFunctionInfo::LineInfo LastSourceLoc, CurSourceLoc;
LastSourceLoc.File = Frag.StartFileId;
LastSourceLoc.Line = Frag.StartLineNum;
SmallVectorImpl<char> &Buffer = Frag.getContents();
Buffer.clear(); // Clear old contents if we went through relaxation.
for (const MCCVLineEntry &Loc : Locs) {
// Exit early if our line table would produce an oversized InlineSiteSym
// record. Account for the ChangeCodeLength annotation emitted after the
// loop ends.
constexpr uint32_t InlineSiteSize = 12;
constexpr uint32_t AnnotationSize = 8;
size_t MaxBufferSize = MaxRecordLength - InlineSiteSize - AnnotationSize;
if (Buffer.size() >= MaxBufferSize)
break;
if (Loc.getFunctionId() == Frag.SiteFuncId) {
CurSourceLoc.File = Loc.getFileNum();
CurSourceLoc.Line = Loc.getLine();
} else {
auto I = SiteInfo->InlinedAtMap.find(Loc.getFunctionId());
if (I != SiteInfo->InlinedAtMap.end()) {
// This .cv_loc is from a child inline call site. Use the source
// location of the inlined call site instead of the .cv_loc directive
// source location.
CurSourceLoc = I->second;
} else {
// We've hit a cv_loc not attributed to this inline call site. Use this
// label to end the PC range.
if (HaveOpenRange) {
unsigned Length = computeLabelDiff(Layout, LastLabel, Loc.getLabel());
compressAnnotation(BinaryAnnotationsOpCode::ChangeCodeLength, Buffer);
compressAnnotation(Length, Buffer);
LastLabel = Loc.getLabel();
}
HaveOpenRange = false;
continue;
}
}
// Skip this .cv_loc if we have an open range and this isn't a meaningful
// source location update. The current table format does not support column
// info, so we can skip updates for those.
if (HaveOpenRange && CurSourceLoc.File == LastSourceLoc.File &&
CurSourceLoc.Line == LastSourceLoc.Line)
continue;
HaveOpenRange = true;
if (CurSourceLoc.File != LastSourceLoc.File) {
unsigned FileOffset = static_cast<const MCConstantExpr *>(
Files[CurSourceLoc.File - 1]
.ChecksumTableOffset->getVariableValue())
->getValue();
compressAnnotation(BinaryAnnotationsOpCode::ChangeFile, Buffer);
compressAnnotation(FileOffset, Buffer);
}
int LineDelta = CurSourceLoc.Line - LastSourceLoc.Line;
unsigned EncodedLineDelta = encodeSignedNumber(LineDelta);
unsigned CodeDelta = computeLabelDiff(Layout, LastLabel, Loc.getLabel());
if (CodeDelta == 0 && LineDelta != 0) {
compressAnnotation(BinaryAnnotationsOpCode::ChangeLineOffset, Buffer);
compressAnnotation(EncodedLineDelta, Buffer);
} else if (EncodedLineDelta < 0x8 && CodeDelta <= 0xf) {
// The ChangeCodeOffsetAndLineOffset combination opcode is used when the
// encoded line delta uses 3 or fewer set bits and the code offset fits
// in one nibble.
unsigned Operand = (EncodedLineDelta << 4) | CodeDelta;
compressAnnotation(BinaryAnnotationsOpCode::ChangeCodeOffsetAndLineOffset,
Buffer);
compressAnnotation(Operand, Buffer);
} else {
// Otherwise use the separate line and code deltas.
if (LineDelta != 0) {
compressAnnotation(BinaryAnnotationsOpCode::ChangeLineOffset, Buffer);
compressAnnotation(EncodedLineDelta, Buffer);
}
compressAnnotation(BinaryAnnotationsOpCode::ChangeCodeOffset, Buffer);
compressAnnotation(CodeDelta, Buffer);
}
LastLabel = Loc.getLabel();
LastSourceLoc = CurSourceLoc;
}
assert(HaveOpenRange);
unsigned EndSymLength =
computeLabelDiff(Layout, LastLabel, Frag.getFnEndSym());
unsigned LocAfterLength = ~0U;
ArrayRef<MCCVLineEntry> LocAfter = getLinesForExtent(LocEnd, LocEnd + 1);
if (!LocAfter.empty()) {
// Only try to compute this difference if we're in the same section.
const MCCVLineEntry &Loc = LocAfter[0];
if (&Loc.getLabel()->getSection() == &LastLabel->getSection())
LocAfterLength = computeLabelDiff(Layout, LastLabel, Loc.getLabel());
}
compressAnnotation(BinaryAnnotationsOpCode::ChangeCodeLength, Buffer);
compressAnnotation(std::min(EndSymLength, LocAfterLength), Buffer);
}
void CodeViewContext::encodeDefRange(MCAsmLayout &Layout,
MCCVDefRangeFragment &Frag) {
MCContext &Ctx = Layout.getAssembler().getContext();
SmallVectorImpl<char> &Contents = Frag.getContents();
Contents.clear();
SmallVectorImpl<MCFixup> &Fixups = Frag.getFixups();
Fixups.clear();
raw_svector_ostream OS(Contents);
// Compute all the sizes up front.
SmallVector<std::pair<unsigned, unsigned>, 4> GapAndRangeSizes;
const MCSymbol *LastLabel = nullptr;
for (std::pair<const MCSymbol *, const MCSymbol *> Range : Frag.getRanges()) {
unsigned GapSize =
LastLabel ? computeLabelDiff(Layout, LastLabel, Range.first) : 0;
unsigned RangeSize = computeLabelDiff(Layout, Range.first, Range.second);
GapAndRangeSizes.push_back({GapSize, RangeSize});
LastLabel = Range.second;
}
// Write down each range where the variable is defined.
for (size_t I = 0, E = Frag.getRanges().size(); I != E;) {
// If the range size of multiple consecutive ranges is under the max,
// combine the ranges and emit some gaps.
const MCSymbol *RangeBegin = Frag.getRanges()[I].first;
unsigned RangeSize = GapAndRangeSizes[I].second;
size_t J = I + 1;
for (; J != E; ++J) {
unsigned GapAndRangeSize = GapAndRangeSizes[J].first + GapAndRangeSizes[J].second;
if (RangeSize + GapAndRangeSize > MaxDefRange)
break;
RangeSize += GapAndRangeSize;
}
unsigned NumGaps = J - I - 1;
support::endian::Writer<support::little> LEWriter(OS);
unsigned Bias = 0;
// We must split the range into chunks of MaxDefRange, this is a fundamental
// limitation of the file format.
do {
uint16_t Chunk = std::min((uint32_t)MaxDefRange, RangeSize);
const MCSymbolRefExpr *SRE = MCSymbolRefExpr::create(RangeBegin, Ctx);
const MCBinaryExpr *BE =
MCBinaryExpr::createAdd(SRE, MCConstantExpr::create(Bias, Ctx), Ctx);
MCValue Res;
BE->evaluateAsRelocatable(Res, &Layout, /*Fixup=*/nullptr);
// Each record begins with a 2-byte number indicating how large the record
// is.
StringRef FixedSizePortion = Frag.getFixedSizePortion();
// Our record is a fixed sized prefix and a LocalVariableAddrRange that we
// are artificially constructing.
size_t RecordSize = FixedSizePortion.size() +
sizeof(LocalVariableAddrRange) + 4 * NumGaps;
// Write out the record size.
LEWriter.write<uint16_t>(RecordSize);
// Write out the fixed size prefix.
OS << FixedSizePortion;
// Make space for a fixup that will eventually have a section relative
// relocation pointing at the offset where the variable becomes live.
Fixups.push_back(MCFixup::create(Contents.size(), BE, FK_SecRel_4));
LEWriter.write<uint32_t>(0); // Fixup for code start.
// Make space for a fixup that will record the section index for the code.
Fixups.push_back(MCFixup::create(Contents.size(), BE, FK_SecRel_2));
LEWriter.write<uint16_t>(0); // Fixup for section index.
// Write down the range's extent.
LEWriter.write<uint16_t>(Chunk);
// Move on to the next range.
Bias += Chunk;
RangeSize -= Chunk;
} while (RangeSize > 0);
// Emit the gaps afterwards.
assert((NumGaps == 0 || Bias <= MaxDefRange) &&
"large ranges should not have gaps");
unsigned GapStartOffset = GapAndRangeSizes[I].second;
for (++I; I != J; ++I) {
unsigned GapSize, RangeSize;
assert(I < GapAndRangeSizes.size());
std::tie(GapSize, RangeSize) = GapAndRangeSizes[I];
LEWriter.write<uint16_t>(GapStartOffset);
LEWriter.write<uint16_t>(GapSize);
GapStartOffset += GapSize + RangeSize;
}
}
}
//
// This is called when an instruction is assembled into the specified section
// and if there is information from the last .cv_loc directive that has yet to have
// a line entry made for it is made.
//
void MCCVLineEntry::Make(MCObjectStreamer *MCOS) {
CodeViewContext &CVC = MCOS->getContext().getCVContext();
if (!CVC.getCVLocSeen())
return;
// Create a symbol at in the current section for use in the line entry.
MCSymbol *LineSym = MCOS->getContext().createTempSymbol();
// Set the value of the symbol to use for the MCCVLineEntry.
MCOS->EmitLabel(LineSym);
// Get the current .loc info saved in the context.
const MCCVLoc &CVLoc = CVC.getCurrentCVLoc();
// Create a (local) line entry with the symbol and the current .loc info.
MCCVLineEntry LineEntry(LineSym, CVLoc);
// clear CVLocSeen saying the current .loc info is now used.
CVC.clearCVLocSeen();
// Add the line entry to this section's entries.
CVC.addLineEntry(LineEntry);
}
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