diff options
Diffstat (limited to 'lib/MC/MCCodeView.cpp')
| -rw-r--r-- | lib/MC/MCCodeView.cpp | 464 |
1 files changed, 464 insertions, 0 deletions
diff --git a/lib/MC/MCCodeView.cpp b/lib/MC/MCCodeView.cpp new file mode 100644 index 000000000000..65cff41abebe --- /dev/null +++ b/lib/MC/MCCodeView.cpp @@ -0,0 +1,464 @@ +//===- 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/MC/MCAsmLayout.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/DebugInfo/CodeView/CodeView.h" +#include "llvm/DebugInfo/CodeView/Line.h" +#include "llvm/DebugInfo/CodeView/SymbolRecord.h" +#include "llvm/MC/MCContext.h" +#include "llvm/MC/MCObjectStreamer.h" +#include "llvm/MC/MCValue.h" +#include "llvm/Support/COFF.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 < Filenames.size()) + return !Filenames[Idx].empty(); + return false; +} + +bool CodeViewContext::addFile(unsigned FileNumber, StringRef Filename) { + assert(FileNumber > 0); + Filename = addToStringTable(Filename); + unsigned Idx = FileNumber - 1; + if (Idx >= Filenames.size()) + Filenames.resize(Idx + 1); + + if (Filename.empty()) + Filename = "<stdin>"; + + if (!Filenames[Idx].empty()) + return false; + + // FIXME: We should store the string table offset of the filename, rather than + // the filename itself for efficiency. + Filename = addToStringTable(Filename); + + Filenames[Idx] = Filename; + 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; +} + +StringRef 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. + S = Insertion.first->first(); + if (Insertion.second) { + // The string map key is always null terminated. + Contents.append(S.begin(), S.end() + 1); + } + return S; +} + +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(ModuleSubstreamKind::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 (Filenames.empty()) + return; + + MCContext &Ctx = OS.getContext(); + MCSymbol *FileBegin = Ctx.createTempSymbol("filechecksums_begin", false), + *FileEnd = Ctx.createTempSymbol("filechecksums_end", false); + + OS.EmitIntValue(unsigned(ModuleSubstreamKind::FileChecksums), 4); + OS.emitAbsoluteSymbolDiff(FileEnd, FileBegin, 4); + OS.EmitLabel(FileBegin); + + // Emit an array of FileChecksum entries. We index into this table using the + // user-provided file number. Each entry is currently 8 bytes, as we don't + // emit checksums. + for (StringRef Filename : Filenames) { + OS.EmitIntValue(getStringTableOffset(Filename), 4); + // Zero the next two fields and align back to 4 bytes. This indicates that + // no checksum is present. + OS.EmitIntValue(0, 4); + } + + OS.EmitLabel(FileEnd); +} + +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(ModuleSubstreamKind::Lines), 4); + OS.emitAbsoluteSymbolDiff(LineEnd, LineBegin, 4); + OS.EmitLabel(LineBegin); + OS.EmitCOFFSecRel32(FuncBegin); + 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(LineFlags::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(Filenames[CurFileNum - 1]) + + "' begins"); + OS.EmitIntValue(8 * (CurFileNum - 1), 4); + 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, ArrayRef<unsigned> SecondaryFunctionIds) { + // Create and insert a fragment into the current section that will be encoded + // later. + new MCCVInlineLineTableFragment( + PrimaryFunctionId, SourceFileId, SourceLineNum, FnStartSym, FnEndSym, + SecondaryFunctionIds, 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); + for (unsigned SecondaryId : Frag.SecondaryFuncs) { + auto Extent = getLineExtent(SecondaryId); + 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; + + SmallSet<unsigned, 8> InlinedFuncIds; + InlinedFuncIds.insert(Frag.SiteFuncId); + InlinedFuncIds.insert(Frag.SecondaryFuncs.begin(), Frag.SecondaryFuncs.end()); + + // 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); + const MCCVLineEntry *LastLoc = &StartLoc; + bool HaveOpenRange = false; + + SmallVectorImpl<char> &Buffer = Frag.getContents(); + Buffer.clear(); // Clear old contents if we went through relaxation. + for (const MCCVLineEntry &Loc : Locs) { + if (!InlinedFuncIds.count(Loc.getFunctionId())) { + // 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, LastLoc->getLabel(), Loc.getLabel()); + compressAnnotation(BinaryAnnotationsOpCode::ChangeCodeLength, Buffer); + compressAnnotation(Length, Buffer); + } + HaveOpenRange = false; + continue; + } + + // If we've already opened the function and we're at an indirectly inlined + // location, continue until the next directly inlined location. + bool DirectlyInlined = Loc.getFunctionId() == Frag.SiteFuncId; + if (!DirectlyInlined && HaveOpenRange) + continue; + HaveOpenRange = true; + + if (Loc.getFileNum() != LastLoc->getFileNum()) { + // File ids are 1 based, and each file checksum table entry is 8 bytes + // long. See emitFileChecksums above. + unsigned FileOffset = 8 * (Loc.getFileNum() - 1); + compressAnnotation(BinaryAnnotationsOpCode::ChangeFile, Buffer); + compressAnnotation(FileOffset, Buffer); + } + + int LineDelta = Loc.getLine() - LastLoc->getLine(); + if (LineDelta == 0) + continue; + + unsigned EncodedLineDelta = encodeSignedNumber(LineDelta); + unsigned CodeDelta = + computeLabelDiff(Layout, LastLoc->getLabel(), Loc.getLabel()); + if (CodeDelta == 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. + compressAnnotation(BinaryAnnotationsOpCode::ChangeLineOffset, Buffer); + compressAnnotation(EncodedLineDelta, Buffer); + compressAnnotation(BinaryAnnotationsOpCode::ChangeCodeOffset, Buffer); + compressAnnotation(CodeDelta, Buffer); + } + + LastLoc = &Loc; + } + + assert(HaveOpenRange); + + unsigned EndSymLength = + computeLabelDiff(Layout, LastLoc->getLabel(), 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(false) == + &LastLoc->getLabel()->getSection(false)) { + LocAfterLength = + computeLabelDiff(Layout, LastLoc->getLabel(), 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); + + // Write down each range where the variable is defined. + for (std::pair<const MCSymbol *, const MCSymbol *> Range : Frag.getRanges()) { + unsigned RangeSize = computeLabelDiff(Layout, Range.first, Range.second); + 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(Range.first, 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); + // Write out the recrod size. + support::endian::Writer<support::little>(OS).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)); + Contents.resize(Contents.size() + 4); // 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)); + Contents.resize(Contents.size() + 2); // Fixup for section index. + // Write down the range's extent. + support::endian::Writer<support::little>(OS).write<uint16_t>(Chunk); + + // Move on to the next range. + Bias += Chunk; + RangeSize -= Chunk; + } while (RangeSize > 0); + } +} + +// +// 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) { + if (!MCOS->getContext().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 = MCOS->getContext().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. + MCOS->getContext().clearCVLocSeen(); + + // Add the line entry to this section's entries. + MCOS->getContext().getCVContext().addLineEntry(LineEntry); +} |