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//===- llvm/CodeGen/DwarfCompileUnit.cpp - Dwarf Compile Units ------------===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// This file contains support for constructing a dwarf compile unit.
#include "DwarfCompileUnit.h"
#include "AddressPool.h"
#include "DwarfExpression.h"
#include "llvm/ADT/None.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/DIE.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/TargetFrameLowering.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCSymbolWasm.h"
#include "llvm/MC/MachineLocation.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include <iterator>
#include <string>
#include <utility>
using namespace llvm;
static dwarf::Tag GetCompileUnitType(UnitKind Kind, DwarfDebug *DW) {
// According to DWARF Debugging Information Format Version 5,
// 3.1.2 Skeleton Compilation Unit Entries:
// "When generating a split DWARF object file (see Section 7.3.2
// on page 187), the compilation unit in the .debug_info section
// is a "skeleton" compilation unit with the tag DW_TAG_skeleton_unit"
if (DW->getDwarfVersion() >= 5 && Kind == UnitKind::Skeleton)
return dwarf::DW_TAG_skeleton_unit;
return dwarf::DW_TAG_compile_unit;
DwarfCompileUnit::DwarfCompileUnit(unsigned UID, const DICompileUnit *Node,
AsmPrinter *A, DwarfDebug *DW,
DwarfFile *DWU, UnitKind Kind)
: DwarfUnit(GetCompileUnitType(Kind, DW), Node, A, DW, DWU), UniqueID(UID) {
insertDIE(Node, &getUnitDie());
MacroLabelBegin = Asm->createTempSymbol("cu_macro_begin");
/// addLabelAddress - Add a dwarf label attribute data and value using
/// DW_FORM_addr or DW_FORM_GNU_addr_index.
void DwarfCompileUnit::addLabelAddress(DIE &Die, dwarf::Attribute Attribute,
const MCSymbol *Label) {
// Don't use the address pool in non-fission or in the skeleton unit itself.
if ((!DD->useSplitDwarf() || !Skeleton) && DD->getDwarfVersion() < 5)
return addLocalLabelAddress(Die, Attribute, Label);
if (Label)
DD->addArangeLabel(SymbolCU(this, Label));
bool UseAddrOffsetFormOrExpressions =
DD->useAddrOffsetForm() || DD->useAddrOffsetExpressions();
const MCSymbol *Base = nullptr;
if (Label->isInSection() && UseAddrOffsetFormOrExpressions)
Base = DD->getSectionLabel(&Label->getSection());
if (!Base || Base == Label) {
unsigned idx = DD->getAddressPool().getIndex(Label);
Die.addValue(DIEValueAllocator, Attribute,
DD->getDwarfVersion() >= 5 ? dwarf::DW_FORM_addrx
: dwarf::DW_FORM_GNU_addr_index,
// Could be extended to work with DWARFv4 Split DWARF if that's important for
// someone. In that case DW_FORM_data would be used.
assert(DD->getDwarfVersion() >= 5 &&
"Addr+offset expressions are only valuable when using debug_addr (to "
"reduce relocations) available in DWARFv5 or higher");
if (DD->useAddrOffsetExpressions()) {
auto *Loc = new (DIEValueAllocator) DIEBlock();
addPoolOpAddress(*Loc, Label);
addBlock(Die, Attribute, dwarf::DW_FORM_exprloc, Loc);
} else
Die.addValue(DIEValueAllocator, Attribute, dwarf::DW_FORM_LLVM_addrx_offset,
new (DIEValueAllocator) DIEAddrOffset(
DD->getAddressPool().getIndex(Base), Label, Base));
void DwarfCompileUnit::addLocalLabelAddress(DIE &Die,
dwarf::Attribute Attribute,
const MCSymbol *Label) {
if (Label)
DD->addArangeLabel(SymbolCU(this, Label));
if (Label)
Die.addValue(DIEValueAllocator, Attribute, dwarf::DW_FORM_addr,
Die.addValue(DIEValueAllocator, Attribute, dwarf::DW_FORM_addr,
unsigned DwarfCompileUnit::getOrCreateSourceID(const DIFile *File) {
// If we print assembly, we can't separate .file entries according to
// compile units. Thus all files will belong to the default compile unit.
// FIXME: add a better feature test than hasRawTextSupport. Even better,
// extend .file to support this.
unsigned CUID = Asm->OutStreamer->hasRawTextSupport() ? 0 : getUniqueID();
if (!File)
return Asm->OutStreamer->emitDwarfFileDirective(0, "", "", None, None,
return Asm->OutStreamer->emitDwarfFileDirective(
0, File->getDirectory(), File->getFilename(), DD->getMD5AsBytes(File),
File->getSource(), CUID);
DIE *DwarfCompileUnit::getOrCreateGlobalVariableDIE(
const DIGlobalVariable *GV, ArrayRef<GlobalExpr> GlobalExprs) {
// Check for pre-existence.
if (DIE *Die = getDIE(GV))
return Die;
auto *GVContext = GV->getScope();
const DIType *GTy = GV->getType();
// Construct the context before querying for the existence of the DIE in
// case such construction creates the DIE.
auto *CB = GVContext ? dyn_cast<DICommonBlock>(GVContext) : nullptr;
DIE *ContextDIE = CB ? getOrCreateCommonBlock(CB, GlobalExprs)
: getOrCreateContextDIE(GVContext);
// Add to map.
DIE *VariableDIE = &createAndAddDIE(GV->getTag(), *ContextDIE, GV);
DIScope *DeclContext;
if (auto *SDMDecl = GV->getStaticDataMemberDeclaration()) {
DeclContext = SDMDecl->getScope();
assert(SDMDecl->isStaticMember() && "Expected static member decl");
// We need the declaration DIE that is in the static member's class.
DIE *VariableSpecDIE = getOrCreateStaticMemberDIE(SDMDecl);
addDIEEntry(*VariableDIE, dwarf::DW_AT_specification, *VariableSpecDIE);
// If the global variable's type is different from the one in the class
// member type, assume that it's more specific and also emit it.
if (GTy != SDMDecl->getBaseType())
addType(*VariableDIE, GTy);
} else {
DeclContext = GV->getScope();
// Add name and type.
addString(*VariableDIE, dwarf::DW_AT_name, GV->getDisplayName());
if (GTy)
addType(*VariableDIE, GTy);
// Add scoping info.
if (!GV->isLocalToUnit())
addFlag(*VariableDIE, dwarf::DW_AT_external);
// Add line number info.
addSourceLine(*VariableDIE, GV);
if (!GV->isDefinition())
addFlag(*VariableDIE, dwarf::DW_AT_declaration);
addGlobalName(GV->getName(), *VariableDIE, DeclContext);
if (uint32_t AlignInBytes = GV->getAlignInBytes())
addUInt(*VariableDIE, dwarf::DW_AT_alignment, dwarf::DW_FORM_udata,
if (MDTuple *TP = GV->getTemplateParams())
addTemplateParams(*VariableDIE, DINodeArray(TP));
// Add location.
addLocationAttribute(VariableDIE, GV, GlobalExprs);
return VariableDIE;
void DwarfCompileUnit::addLocationAttribute(
DIE *VariableDIE, const DIGlobalVariable *GV, ArrayRef<GlobalExpr> GlobalExprs) {
bool addToAccelTable = false;
DIELoc *Loc = nullptr;
Optional<unsigned> NVPTXAddressSpace;
std::unique_ptr<DIEDwarfExpression> DwarfExpr;
for (const auto &GE : GlobalExprs) {
const GlobalVariable *Global = GE.Var;
const DIExpression *Expr = GE.Expr;
// For compatibility with DWARF 3 and earlier,
// DW_AT_location(DW_OP_constu, X, DW_OP_stack_value) becomes
// DW_AT_const_value(X).
if (GlobalExprs.size() == 1 && Expr && Expr->isConstant()) {
addToAccelTable = true;
addConstantValue(*VariableDIE, /*Unsigned=*/true, Expr->getElement(1));
// We cannot describe the location of dllimport'd variables: the
// computation of their address requires loads from the IAT.
if (Global && Global->hasDLLImportStorageClass())
// Nothing to describe without address or constant.
if (!Global && (!Expr || !Expr->isConstant()))
if (Global && Global->isThreadLocal() &&
if (!Loc) {
addToAccelTable = true;
Loc = new (DIEValueAllocator) DIELoc;
DwarfExpr = std::make_unique<DIEDwarfExpression>(*Asm, *this, *Loc);
if (Expr) {
// According to
// cuda-gdb requires DW_AT_address_class for all variables to be able to
// correctly interpret address space of the variable address.
// Decode DW_OP_constu <DWARF Address Space> DW_OP_swap DW_OP_xderef
// sequence for the NVPTX + gdb target.
unsigned LocalNVPTXAddressSpace;
if (Asm->TM.getTargetTriple().isNVPTX() && DD->tuneForGDB()) {
const DIExpression *NewExpr =
DIExpression::extractAddressClass(Expr, LocalNVPTXAddressSpace);
if (NewExpr != Expr) {
Expr = NewExpr;
NVPTXAddressSpace = LocalNVPTXAddressSpace;
if (Global) {
const MCSymbol *Sym = Asm->getSymbol(Global);
if (Global->isThreadLocal()) {
if (Asm->TM.useEmulatedTLS()) {
// TODO: add debug info for emulated thread local mode.
} else {
// FIXME: Make this work with -gsplit-dwarf.
unsigned PointerSize = Asm->getDataLayout().getPointerSize();
assert((PointerSize == 4 || PointerSize == 8) &&
"Add support for other sizes if necessary");
// Based on GCC's support for TLS:
if (!DD->useSplitDwarf()) {
// 1) Start with a constNu of the appropriate pointer size
addUInt(*Loc, dwarf::DW_FORM_data1,
PointerSize == 4 ? dwarf::DW_OP_const4u
: dwarf::DW_OP_const8u);
// 2) containing the (relocated) offset of the TLS variable
// within the module's TLS block.
PointerSize == 4 ? dwarf::DW_FORM_data4
: dwarf::DW_FORM_data8,
} else {
addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_GNU_const_index);
addUInt(*Loc, dwarf::DW_FORM_udata,
DD->getAddressPool().getIndex(Sym, /* TLS */ true));
// 3) followed by an OP to make the debugger do a TLS lookup.
addUInt(*Loc, dwarf::DW_FORM_data1,
DD->useGNUTLSOpcode() ? dwarf::DW_OP_GNU_push_tls_address
: dwarf::DW_OP_form_tls_address);
} else {
DD->addArangeLabel(SymbolCU(this, Sym));
addOpAddress(*Loc, Sym);
// Global variables attached to symbols are memory locations.
// It would be better if this were unconditional, but malformed input that
// mixes non-fragments and fragments for the same variable is too expensive
// to detect in the verifier.
if (DwarfExpr->isUnknownLocation())
if (Asm->TM.getTargetTriple().isNVPTX() && DD->tuneForGDB()) {
// According to
// cuda-gdb requires DW_AT_address_class for all variables to be able to
// correctly interpret address space of the variable address.
const unsigned NVPTX_ADDR_global_space = 5;
addUInt(*VariableDIE, dwarf::DW_AT_address_class, dwarf::DW_FORM_data1,
NVPTXAddressSpace ? *NVPTXAddressSpace : NVPTX_ADDR_global_space);
if (Loc)
addBlock(*VariableDIE, dwarf::DW_AT_location, DwarfExpr->finalize());
if (DD->useAllLinkageNames())
addLinkageName(*VariableDIE, GV->getLinkageName());
if (addToAccelTable) {
DD->addAccelName(*CUNode, GV->getName(), *VariableDIE);
// If the linkage name is different than the name, go ahead and output
// that as well into the name table.
if (GV->getLinkageName() != "" && GV->getName() != GV->getLinkageName() &&
DD->addAccelName(*CUNode, GV->getLinkageName(), *VariableDIE);
DIE *DwarfCompileUnit::getOrCreateCommonBlock(
const DICommonBlock *CB, ArrayRef<GlobalExpr> GlobalExprs) {
// Construct the context before querying for the existence of the DIE in case
// such construction creates the DIE.
DIE *ContextDIE = getOrCreateContextDIE(CB->getScope());
if (DIE *NDie = getDIE(CB))
return NDie;
DIE &NDie = createAndAddDIE(dwarf::DW_TAG_common_block, *ContextDIE, CB);
StringRef Name = CB->getName().empty() ? "_BLNK_" : CB->getName();
addString(NDie, dwarf::DW_AT_name, Name);
addGlobalName(Name, NDie, CB->getScope());
if (CB->getFile())
addSourceLine(NDie, CB->getLineNo(), CB->getFile());
if (DIGlobalVariable *V = CB->getDecl())
getCU().addLocationAttribute(&NDie, V, GlobalExprs);
return &NDie;
void DwarfCompileUnit::addRange(RangeSpan Range) {
bool SameAsPrevCU = this == DD->getPrevCU();
// If we have no current ranges just add the range and return, otherwise,
// check the current section and CU against the previous section and CU we
// emitted into and the subprogram was contained within. If these are the
// same then extend our current range, otherwise add this as a new range.
if (CURanges.empty() || !SameAsPrevCU ||
(&CURanges.back().End->getSection() !=
&Range.End->getSection())) {
CURanges.back().End = Range.End;
void DwarfCompileUnit::initStmtList() {
if (CUNode->isDebugDirectivesOnly())
const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
if (DD->useSectionsAsReferences()) {
LineTableStartSym = TLOF.getDwarfLineSection()->getBeginSymbol();
} else {
LineTableStartSym =
// DW_AT_stmt_list is a offset of line number information for this
// compile unit in debug_line section. For split dwarf this is
// left in the skeleton CU and so not included.
// The line table entries are not always emitted in assembly, so it
// is not okay to use line_table_start here.
addSectionLabel(getUnitDie(), dwarf::DW_AT_stmt_list, LineTableStartSym,
void DwarfCompileUnit::applyStmtList(DIE &D) {
const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
addSectionLabel(D, dwarf::DW_AT_stmt_list, LineTableStartSym,
void DwarfCompileUnit::attachLowHighPC(DIE &D, const MCSymbol *Begin,
const MCSymbol *End) {
assert(Begin && "Begin label should not be null!");
assert(End && "End label should not be null!");
assert(Begin->isDefined() && "Invalid starting label");
assert(End->isDefined() && "Invalid end label");
addLabelAddress(D, dwarf::DW_AT_low_pc, Begin);
if (DD->getDwarfVersion() < 4)
addLabelAddress(D, dwarf::DW_AT_high_pc, End);
addLabelDelta(D, dwarf::DW_AT_high_pc, End, Begin);
// Find DIE for the given subprogram and attach appropriate DW_AT_low_pc
// and DW_AT_high_pc attributes. If there are global variables in this
// scope then create and insert DIEs for these variables.
DIE &DwarfCompileUnit::updateSubprogramScopeDIE(const DISubprogram *SP) {
DIE *SPDie = getOrCreateSubprogramDIE(SP, includeMinimalInlineScopes());
SmallVector<RangeSpan, 2> BB_List;
// If basic block sections are on, ranges for each basic block section has
// to be emitted separately.
for (const auto &R : Asm->MBBSectionRanges)
BB_List.push_back({R.second.BeginLabel, R.second.EndLabel});
attachRangesOrLowHighPC(*SPDie, BB_List);
if (DD->useAppleExtensionAttributes() &&
addFlag(*SPDie, dwarf::DW_AT_APPLE_omit_frame_ptr);
// Only include DW_AT_frame_base in full debug info
if (!includeMinimalInlineScopes()) {
const TargetFrameLowering *TFI = Asm->MF->getSubtarget().getFrameLowering();
TargetFrameLowering::DwarfFrameBase FrameBase =
switch (FrameBase.Kind) {
case TargetFrameLowering::DwarfFrameBase::Register: {
if (Register::isPhysicalRegister(FrameBase.Location.Reg)) {
MachineLocation Location(FrameBase.Location.Reg);
addAddress(*SPDie, dwarf::DW_AT_frame_base, Location);
case TargetFrameLowering::DwarfFrameBase::CFA: {
DIELoc *Loc = new (DIEValueAllocator) DIELoc;
addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_call_frame_cfa);
addBlock(*SPDie, dwarf::DW_AT_frame_base, Loc);
case TargetFrameLowering::DwarfFrameBase::WasmFrameBase: {
// FIXME: duplicated from Target/WebAssembly/WebAssembly.h
// don't want to depend on target specific headers in this code?
const unsigned TI_GLOBAL_RELOC = 3;
// FIXME: when writing dwo, we need to avoid relocations. Probably
// the "right" solution is to treat globals the way func and data symbols
// are (with entries in .debug_addr).
if (FrameBase.Location.WasmLoc.Kind == TI_GLOBAL_RELOC && !isDwoUnit()) {
// These need to be relocatable.
assert(FrameBase.Location.WasmLoc.Index == 0); // Only SP so far.
auto SPSym = cast<MCSymbolWasm>(
// FIXME: this repeats what WebAssemblyMCInstLower::
// GetExternalSymbolSymbol does, since if there's no code that
// refers to this symbol, we have to set it here.
uint8_t(Asm->getSubtargetInfo().getTargetTriple().getArch() ==
? wasm::WASM_TYPE_I64
: wasm::WASM_TYPE_I32),
DIELoc *Loc = new (DIEValueAllocator) DIELoc;
addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_WASM_location);
addSInt(*Loc, dwarf::DW_FORM_sdata, TI_GLOBAL_RELOC);
addLabel(*Loc, dwarf::DW_FORM_data4, SPSym);
DD->addArangeLabel(SymbolCU(this, SPSym));
addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_stack_value);
addBlock(*SPDie, dwarf::DW_AT_frame_base, Loc);
} else {
DIELoc *Loc = new (DIEValueAllocator) DIELoc;
DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
DIExpressionCursor Cursor({});
addBlock(*SPDie, dwarf::DW_AT_frame_base, DwarfExpr.finalize());
// Add name to the name table, we do this here because we're guaranteed
// to have concrete versions of our DW_TAG_subprogram nodes.
DD->addSubprogramNames(*CUNode, SP, *SPDie);
return *SPDie;
// Construct a DIE for this scope.
void DwarfCompileUnit::constructScopeDIE(
LexicalScope *Scope, SmallVectorImpl<DIE *> &FinalChildren) {
if (!Scope || !Scope->getScopeNode())
auto *DS = Scope->getScopeNode();
assert((Scope->getInlinedAt() || !isa<DISubprogram>(DS)) &&
"Only handle inlined subprograms here, use "
"constructSubprogramScopeDIE for non-inlined "
SmallVector<DIE *, 8> Children;
// We try to create the scope DIE first, then the children DIEs. This will
// avoid creating un-used children then removing them later when we find out
// the scope DIE is null.
DIE *ScopeDIE;
if (Scope->getParent() && isa<DISubprogram>(DS)) {
ScopeDIE = constructInlinedScopeDIE(Scope);
if (!ScopeDIE)
// We create children when the scope DIE is not null.
createScopeChildrenDIE(Scope, Children);
} else {
// Early exit when we know the scope DIE is going to be null.
if (DD->isLexicalScopeDIENull(Scope))
bool HasNonScopeChildren = false;
// We create children here when we know the scope DIE is not going to be
// null and the children will be added to the scope DIE.
createScopeChildrenDIE(Scope, Children, &HasNonScopeChildren);
// If there are only other scopes as children, put them directly in the
// parent instead, as this scope would serve no purpose.
if (!HasNonScopeChildren) {
ScopeDIE = constructLexicalScopeDIE(Scope);
assert(ScopeDIE && "Scope DIE should not be null.");
// Add children
for (auto &I : Children)
void DwarfCompileUnit::addScopeRangeList(DIE &ScopeDIE,
SmallVector<RangeSpan, 2> Range) {
HasRangeLists = true;
// Add the range list to the set of ranges to be emitted.
auto IndexAndList =
(DD->getDwarfVersion() < 5 && Skeleton ? Skeleton->DU : DU)
->addRange(*(Skeleton ? Skeleton : this), std::move(Range));
uint32_t Index = IndexAndList.first;
auto &List = *IndexAndList.second;
// Under fission, ranges are specified by constant offsets relative to the
// CU's DW_AT_GNU_ranges_base.
// FIXME: For DWARF v5, do not generate the DW_AT_ranges attribute under
// fission until we support the forms using the .debug_addr section
// (DW_RLE_startx_endx etc.).
if (DD->getDwarfVersion() >= 5)
addUInt(ScopeDIE, dwarf::DW_AT_ranges, dwarf::DW_FORM_rnglistx, Index);
else {
const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
const MCSymbol *RangeSectionSym =
if (isDwoUnit())
addSectionDelta(ScopeDIE, dwarf::DW_AT_ranges, List.Label,
addSectionLabel(ScopeDIE, dwarf::DW_AT_ranges, List.Label,
void DwarfCompileUnit::attachRangesOrLowHighPC(
DIE &Die, SmallVector<RangeSpan, 2> Ranges) {
if (!DD->useRangesSection() ||
(Ranges.size() == 1 &&
(!DD->alwaysUseRanges() ||
DD->getSectionLabel(&Ranges.front().Begin->getSection()) ==
Ranges.front().Begin))) {
const RangeSpan &Front = Ranges.front();
const RangeSpan &Back = Ranges.back();
attachLowHighPC(Die, Front.Begin, Back.End);
} else
addScopeRangeList(Die, std::move(Ranges));
void DwarfCompileUnit::attachRangesOrLowHighPC(
DIE &Die, const SmallVectorImpl<InsnRange> &Ranges) {
SmallVector<RangeSpan, 2> List;
for (const InsnRange &R : Ranges) {
auto *BeginLabel = DD->getLabelBeforeInsn(R.first);
auto *EndLabel = DD->getLabelAfterInsn(R.second);
const auto *BeginMBB = R.first->getParent();
const auto *EndMBB = R.second->getParent();
const auto *MBB = BeginMBB;
// Basic block sections allows basic block subsets to be placed in unique
// sections. For each section, the begin and end label must be added to the
// list. If there is more than one range, debug ranges must be used.
// Otherwise, low/high PC can be used.
// FIXME: Debug Info Emission depends on block order and this assumes that
// the order of blocks will be frozen beyond this point.
do {
if (MBB->sameSection(EndMBB) || MBB->isEndSection()) {
auto MBBSectionRange = Asm->MBBSectionRanges[MBB->getSectionIDNum()];
{MBB->sameSection(BeginMBB) ? BeginLabel
: MBBSectionRange.BeginLabel,
MBB->sameSection(EndMBB) ? EndLabel : MBBSectionRange.EndLabel});
if (MBB->sameSection(EndMBB))
MBB = MBB->getNextNode();
} while (true);
attachRangesOrLowHighPC(Die, std::move(List));
// This scope represents inlined body of a function. Construct DIE to
// represent this concrete inlined copy of the function.
DIE *DwarfCompileUnit::constructInlinedScopeDIE(LexicalScope *Scope) {
auto *DS = Scope->getScopeNode();
auto *InlinedSP = getDISubprogram(DS);
// Find the subprogram's DwarfCompileUnit in the SPMap in case the subprogram
// was inlined from another compile unit.
DIE *OriginDIE = getAbstractSPDies()[InlinedSP];
assert(OriginDIE && "Unable to find original DIE for an inlined subprogram.");
auto ScopeDIE = DIE::get(DIEValueAllocator, dwarf::DW_TAG_inlined_subroutine);
addDIEEntry(*ScopeDIE, dwarf::DW_AT_abstract_origin, *OriginDIE);
attachRangesOrLowHighPC(*ScopeDIE, Scope->getRanges());
// Add the call site information to the DIE.
const DILocation *IA = Scope->getInlinedAt();
addUInt(*ScopeDIE, dwarf::DW_AT_call_file, None,
addUInt(*ScopeDIE, dwarf::DW_AT_call_line, None, IA->getLine());
if (IA->getColumn())
addUInt(*ScopeDIE, dwarf::DW_AT_call_column, None, IA->getColumn());
if (IA->getDiscriminator() && DD->getDwarfVersion() >= 4)
addUInt(*ScopeDIE, dwarf::DW_AT_GNU_discriminator, None,
// Add name to the name table, we do this here because we're guaranteed
// to have concrete versions of our DW_TAG_inlined_subprogram nodes.
DD->addSubprogramNames(*CUNode, InlinedSP, *ScopeDIE);
return ScopeDIE;
// Construct new DW_TAG_lexical_block for this scope and attach
// DW_AT_low_pc/DW_AT_high_pc labels.
DIE *DwarfCompileUnit::constructLexicalScopeDIE(LexicalScope *Scope) {
if (DD->isLexicalScopeDIENull(Scope))
return nullptr;
auto ScopeDIE = DIE::get(DIEValueAllocator, dwarf::DW_TAG_lexical_block);
if (Scope->isAbstractScope())
return ScopeDIE;
attachRangesOrLowHighPC(*ScopeDIE, Scope->getRanges());
return ScopeDIE;
/// constructVariableDIE - Construct a DIE for the given DbgVariable.
DIE *DwarfCompileUnit::constructVariableDIE(DbgVariable &DV, bool Abstract) {
auto D = constructVariableDIEImpl(DV, Abstract);
return D;
DIE *DwarfCompileUnit::constructLabelDIE(DbgLabel &DL,
const LexicalScope &Scope) {
auto LabelDie = DIE::get(DIEValueAllocator, DL.getTag());
insertDIE(DL.getLabel(), LabelDie);
if (Scope.isAbstractScope())
applyLabelAttributes(DL, *LabelDie);
return LabelDie;
DIE *DwarfCompileUnit::constructVariableDIEImpl(const DbgVariable &DV,
bool Abstract) {
// Define variable debug information entry.
auto VariableDie = DIE::get(DIEValueAllocator, DV.getTag());
insertDIE(DV.getVariable(), VariableDie);
if (Abstract) {
applyVariableAttributes(DV, *VariableDie);
return VariableDie;
// Add variable address.
unsigned Index = DV.getDebugLocListIndex();
if (Index != ~0U) {
addLocationList(*VariableDie, dwarf::DW_AT_location, Index);
auto TagOffset = DV.getDebugLocListTagOffset();
if (TagOffset)
addUInt(*VariableDie, dwarf::DW_AT_LLVM_tag_offset, dwarf::DW_FORM_data1,
return VariableDie;
// Check if variable has a single location description.
if (auto *DVal = DV.getValueLoc()) {
if (DVal->isLocation())
addVariableAddress(DV, *VariableDie, DVal->getLoc());
else if (DVal->isInt()) {
auto *Expr = DV.getSingleExpression();
if (Expr && Expr->getNumElements()) {
DIELoc *Loc = new (DIEValueAllocator) DIELoc;
DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
// If there is an expression, emit raw unsigned bytes.
addBlock(*VariableDie, dwarf::DW_AT_location, DwarfExpr.finalize());
if (DwarfExpr.TagOffset)
addUInt(*VariableDie, dwarf::DW_AT_LLVM_tag_offset,
dwarf::DW_FORM_data1, *DwarfExpr.TagOffset);
} else
addConstantValue(*VariableDie, DVal->getInt(), DV.getType());
} else if (DVal->isConstantFP()) {
addConstantFPValue(*VariableDie, DVal->getConstantFP());
} else if (DVal->isConstantInt()) {
addConstantValue(*VariableDie, DVal->getConstantInt(), DV.getType());
} else if (DVal->isTargetIndexLocation()) {
DIELoc *Loc = new (DIEValueAllocator) DIELoc;
DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
const DIBasicType *BT = dyn_cast<DIBasicType>(
static_cast<const Metadata *>(DV.getVariable()->getType()));
DwarfDebug::emitDebugLocValue(*Asm, BT, *DVal, DwarfExpr);
addBlock(*VariableDie, dwarf::DW_AT_location, DwarfExpr.finalize());
return VariableDie;
// .. else use frame index.
if (!DV.hasFrameIndexExprs())
return VariableDie;
Optional<unsigned> NVPTXAddressSpace;
DIELoc *Loc = new (DIEValueAllocator) DIELoc;
DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
for (auto &Fragment : DV.getFrameIndexExprs()) {
Register FrameReg;
const DIExpression *Expr = Fragment.Expr;
const TargetFrameLowering *TFI = Asm->MF->getSubtarget().getFrameLowering();
StackOffset Offset =
TFI->getFrameIndexReference(*Asm->MF, Fragment.FI, FrameReg);
auto *TRI = Asm->MF->getSubtarget().getRegisterInfo();
SmallVector<uint64_t, 8> Ops;
TRI->getOffsetOpcodes(Offset, Ops);
// According to
// cuda-gdb requires DW_AT_address_class for all variables to be able to
// correctly interpret address space of the variable address.
// Decode DW_OP_constu <DWARF Address Space> DW_OP_swap DW_OP_xderef
// sequence for the NVPTX + gdb target.
unsigned LocalNVPTXAddressSpace;
if (Asm->TM.getTargetTriple().isNVPTX() && DD->tuneForGDB()) {
const DIExpression *NewExpr =
DIExpression::extractAddressClass(Expr, LocalNVPTXAddressSpace);
if (NewExpr != Expr) {
Expr = NewExpr;
NVPTXAddressSpace = LocalNVPTXAddressSpace;
if (Expr)
Ops.append(Expr->elements_begin(), Expr->elements_end());
DIExpressionCursor Cursor(Ops);
if (const MCSymbol *FrameSymbol = Asm->getFunctionFrameSymbol())
addOpAddress(*Loc, FrameSymbol);
*Asm->MF->getSubtarget().getRegisterInfo(), Cursor, FrameReg);
if (Asm->TM.getTargetTriple().isNVPTX() && DD->tuneForGDB()) {
// According to
// cuda-gdb requires DW_AT_address_class for all variables to be able to
// correctly interpret address space of the variable address.
const unsigned NVPTX_ADDR_local_space = 6;
addUInt(*VariableDie, dwarf::DW_AT_address_class, dwarf::DW_FORM_data1,
NVPTXAddressSpace ? *NVPTXAddressSpace : NVPTX_ADDR_local_space);
addBlock(*VariableDie, dwarf::DW_AT_location, DwarfExpr.finalize());
if (DwarfExpr.TagOffset)
addUInt(*VariableDie, dwarf::DW_AT_LLVM_tag_offset, dwarf::DW_FORM_data1,
return VariableDie;
DIE *DwarfCompileUnit::constructVariableDIE(DbgVariable &DV,
const LexicalScope &Scope,
DIE *&ObjectPointer) {
auto Var = constructVariableDIE(DV, Scope.isAbstractScope());
if (DV.isObjectPointer())
ObjectPointer = Var;
return Var;
/// Return all DIVariables that appear in count: expressions.
static SmallVector<const DIVariable *, 2> dependencies(DbgVariable *Var) {
SmallVector<const DIVariable *, 2> Result;
auto *Array = dyn_cast<DICompositeType>(Var->getType());
if (!Array || Array->getTag() != dwarf::DW_TAG_array_type)
return Result;
if (auto *DLVar = Array->getDataLocation())
if (auto *AsVar = Array->getAssociated())
if (auto *AlVar = Array->getAllocated())
for (auto *El : Array->getElements()) {
if (auto *Subrange = dyn_cast<DISubrange>(El)) {
if (auto Count = Subrange->getCount())
if (auto *Dependency = Count.dyn_cast<DIVariable *>())
if (auto LB = Subrange->getLowerBound())
if (auto *Dependency = LB.dyn_cast<DIVariable *>())
if (auto UB = Subrange->getUpperBound())
if (auto *Dependency = UB.dyn_cast<DIVariable *>())
if (auto ST = Subrange->getStride())
if (auto *Dependency = ST.dyn_cast<DIVariable *>())
} else if (auto *GenericSubrange = dyn_cast<DIGenericSubrange>(El)) {
if (auto Count = GenericSubrange->getCount())
if (auto *Dependency = Count.dyn_cast<DIVariable *>())
if (auto LB = GenericSubrange->getLowerBound())
if (auto *Dependency = LB.dyn_cast<DIVariable *>())
if (auto UB = GenericSubrange->getUpperBound())
if (auto *Dependency = UB.dyn_cast<DIVariable *>())
if (auto ST = GenericSubrange->getStride())
if (auto *Dependency = ST.dyn_cast<DIVariable *>())
return Result;
/// Sort local variables so that variables appearing inside of helper
/// expressions come first.
static SmallVector<DbgVariable *, 8>
sortLocalVars(SmallVectorImpl<DbgVariable *> &Input) {
SmallVector<DbgVariable *, 8> Result;
SmallVector<PointerIntPair<DbgVariable *, 1>, 8> WorkList;
// Map back from a DIVariable to its containing DbgVariable.
SmallDenseMap<const DILocalVariable *, DbgVariable *> DbgVar;
// Set of DbgVariables in Result.
SmallDenseSet<DbgVariable *, 8> Visited;
// For cycle detection.
SmallDenseSet<DbgVariable *, 8> Visiting;
// Initialize the worklist and the DIVariable lookup table.
for (auto Var : reverse(Input)) {
DbgVar.insert({Var->getVariable(), Var});
WorkList.push_back({Var, 0});
// Perform a stable topological sort by doing a DFS.
while (!WorkList.empty()) {
auto Item = WorkList.back();
DbgVariable *Var = Item.getPointer();
bool visitedAllDependencies = Item.getInt();
// Dependency is in a different lexical scope or a global.
if (!Var)
// Already handled.
if (Visited.count(Var))
// Add to Result if all dependencies are visited.
if (visitedAllDependencies) {
// Detect cycles.
auto Res = Visiting.insert(Var);
if (!Res.second) {
assert(false && "dependency cycle in local variables");
return Result;
// Push dependencies and this node onto the worklist, so that this node is
// visited again after all of its dependencies are handled.
WorkList.push_back({Var, 1});
for (auto *Dependency : dependencies(Var)) {
auto Dep = dyn_cast_or_null<const DILocalVariable>(Dependency);
WorkList.push_back({DbgVar[Dep], 0});
return Result;
DIE *DwarfCompileUnit::createScopeChildrenDIE(LexicalScope *Scope,
SmallVectorImpl<DIE *> &Children,
bool *HasNonScopeChildren) {
DIE *ObjectPointer = nullptr;
// Emit function arguments (order is significant).
auto Vars = DU->getScopeVariables().lookup(Scope);
for (auto &DV : Vars.Args)
Children.push_back(constructVariableDIE(*DV.second, *Scope, ObjectPointer));
// Emit local variables.
auto Locals = sortLocalVars(Vars.Locals);
for (DbgVariable *DV : Locals)
Children.push_back(constructVariableDIE(*DV, *Scope, ObjectPointer));
// Skip imported directives in gmlt-like data.
if (!includeMinimalInlineScopes()) {
// There is no need to emit empty lexical block DIE.
for (const auto *IE : ImportedEntities[Scope->getScopeNode()])
if (HasNonScopeChildren)
*HasNonScopeChildren = !Children.empty();
for (DbgLabel *DL : DU->getScopeLabels().lookup(Scope))
Children.push_back(constructLabelDIE(*DL, *Scope));
for (LexicalScope *LS : Scope->getChildren())
constructScopeDIE(LS, Children);
return ObjectPointer;
DIE &DwarfCompileUnit::constructSubprogramScopeDIE(const DISubprogram *Sub,
LexicalScope *Scope) {
DIE &ScopeDIE = updateSubprogramScopeDIE(Sub);
if (Scope) {
// Collect lexical scope children first.
// ObjectPointer might be a local (non-argument) local variable if it's a
// block's synthetic this pointer.
if (DIE *ObjectPointer = createAndAddScopeChildren(Scope, ScopeDIE))
addDIEEntry(ScopeDIE, dwarf::DW_AT_object_pointer, *ObjectPointer);
// If this is a variadic function, add an unspecified parameter.
DITypeRefArray FnArgs = Sub->getType()->getTypeArray();
// If we have a single element of null, it is a function that returns void.
// If we have more than one elements and the last one is null, it is a
// variadic function.
if (FnArgs.size() > 1 && !FnArgs[FnArgs.size() - 1] &&
DIE::get(DIEValueAllocator, dwarf::DW_TAG_unspecified_parameters));
return ScopeDIE;
DIE *DwarfCompileUnit::createAndAddScopeChildren(LexicalScope *Scope,
DIE &ScopeDIE) {
// We create children when the scope DIE is not null.
SmallVector<DIE *, 8> Children;
DIE *ObjectPointer = createScopeChildrenDIE(Scope, Children);
// Add children
for (auto &I : Children)
return ObjectPointer;
void DwarfCompileUnit::constructAbstractSubprogramScopeDIE(
LexicalScope *Scope) {
DIE *&AbsDef = getAbstractSPDies()[Scope->getScopeNode()];
if (AbsDef)
auto *SP = cast<DISubprogram>(Scope->getScopeNode());
DIE *ContextDIE;
DwarfCompileUnit *ContextCU = this;
if (includeMinimalInlineScopes())
ContextDIE = &getUnitDie();
// Some of this is duplicated from DwarfUnit::getOrCreateSubprogramDIE, with
// the important distinction that the debug node is not associated with the
// DIE (since the debug node will be associated with the concrete DIE, if
// any). It could be refactored to some common utility function.
else if (auto *SPDecl = SP->getDeclaration()) {
ContextDIE = &getUnitDie();
} else {
ContextDIE = getOrCreateContextDIE(SP->getScope());
// The scope may be shared with a subprogram that has already been
// constructed in another CU, in which case we need to construct this
// subprogram in the same CU.
ContextCU = DD->lookupCU(ContextDIE->getUnitDie());
// Passing null as the associated node because the abstract definition
// shouldn't be found by lookup.
AbsDef = &ContextCU->createAndAddDIE(dwarf::DW_TAG_subprogram, *ContextDIE, nullptr);
ContextCU->applySubprogramAttributesToDefinition(SP, *AbsDef);
if (!ContextCU->includeMinimalInlineScopes())
ContextCU->addUInt(*AbsDef, dwarf::DW_AT_inline, None, dwarf::DW_INL_inlined);
if (DIE *ObjectPointer = ContextCU->createAndAddScopeChildren(Scope, *AbsDef))
ContextCU->addDIEEntry(*AbsDef, dwarf::DW_AT_object_pointer, *ObjectPointer);
bool DwarfCompileUnit::useGNUAnalogForDwarf5Feature() const {
return DD->getDwarfVersion() == 4 && !DD->tuneForLLDB();
dwarf::Tag DwarfCompileUnit::getDwarf5OrGNUTag(dwarf::Tag Tag) const {
if (!useGNUAnalogForDwarf5Feature())
return Tag;
switch (Tag) {
case dwarf::DW_TAG_call_site:
return dwarf::DW_TAG_GNU_call_site;
case dwarf::DW_TAG_call_site_parameter:
return dwarf::DW_TAG_GNU_call_site_parameter;
llvm_unreachable("DWARF5 tag with no GNU analog");
DwarfCompileUnit::getDwarf5OrGNUAttr(dwarf::Attribute Attr) const {
if (!useGNUAnalogForDwarf5Feature())
return Attr;
switch (Attr) {
case dwarf::DW_AT_call_all_calls:
return dwarf::DW_AT_GNU_all_call_sites;
case dwarf::DW_AT_call_target:
return dwarf::DW_AT_GNU_call_site_target;
case dwarf::DW_AT_call_origin:
return dwarf::DW_AT_abstract_origin;
case dwarf::DW_AT_call_return_pc:
return dwarf::DW_AT_low_pc;
case dwarf::DW_AT_call_value:
return dwarf::DW_AT_GNU_call_site_value;
case dwarf::DW_AT_call_tail_call:
return dwarf::DW_AT_GNU_tail_call;
llvm_unreachable("DWARF5 attribute with no GNU analog");
DwarfCompileUnit::getDwarf5OrGNULocationAtom(dwarf::LocationAtom Loc) const {
if (!useGNUAnalogForDwarf5Feature())
return Loc;
switch (Loc) {
case dwarf::DW_OP_entry_value:
return dwarf::DW_OP_GNU_entry_value;
llvm_unreachable("DWARF5 location atom with no GNU analog");
DIE &DwarfCompileUnit::constructCallSiteEntryDIE(DIE &ScopeDIE,
DIE *CalleeDIE,
bool IsTail,
const MCSymbol *PCAddr,
const MCSymbol *CallAddr,
unsigned CallReg) {
// Insert a call site entry DIE within ScopeDIE.
DIE &CallSiteDIE = createAndAddDIE(getDwarf5OrGNUTag(dwarf::DW_TAG_call_site),
ScopeDIE, nullptr);
if (CallReg) {
// Indirect call.
addAddress(CallSiteDIE, getDwarf5OrGNUAttr(dwarf::DW_AT_call_target),
} else {
assert(CalleeDIE && "No DIE for call site entry origin");
addDIEEntry(CallSiteDIE, getDwarf5OrGNUAttr(dwarf::DW_AT_call_origin),
if (IsTail) {
// Attach DW_AT_call_tail_call to tail calls for standards compliance.
addFlag(CallSiteDIE, getDwarf5OrGNUAttr(dwarf::DW_AT_call_tail_call));
// Attach the address of the branch instruction to allow the debugger to
// show where the tail call occurred. This attribute has no GNU analog.
// GDB works backwards from non-standard usage of DW_AT_low_pc (in DWARF4
// mode -- equivalently, in DWARF5 mode, DW_AT_call_return_pc) at tail-call
// site entries to figure out the PC of tail-calling branch instructions.
// This means it doesn't need the compiler to emit DW_AT_call_pc, so we
// don't emit it here.
// There's no need to tie non-GDB debuggers to this non-standardness, as it
// adds unnecessary complexity to the debugger. For non-GDB debuggers, emit
// the standard DW_AT_call_pc info.
if (!useGNUAnalogForDwarf5Feature())
addLabelAddress(CallSiteDIE, dwarf::DW_AT_call_pc, CallAddr);
// Attach the return PC to allow the debugger to disambiguate call paths
// from one function to another.
// The return PC is only really needed when the call /isn't/ a tail call, but
// GDB expects it in DWARF4 mode, even for tail calls (see the comment above
// the DW_AT_call_pc emission logic for an explanation).
if (!IsTail || useGNUAnalogForDwarf5Feature()) {
assert(PCAddr && "Missing return PC information for a call");
getDwarf5OrGNUAttr(dwarf::DW_AT_call_return_pc), PCAddr);
return CallSiteDIE;
void DwarfCompileUnit::constructCallSiteParmEntryDIEs(
DIE &CallSiteDIE, SmallVector<DbgCallSiteParam, 4> &Params) {
for (const auto &Param : Params) {
unsigned Register = Param.getRegister();
auto CallSiteDieParam =
addAddress(*CallSiteDieParam, dwarf::DW_AT_location,
DIELoc *Loc = new (DIEValueAllocator) DIELoc;
DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
DwarfDebug::emitDebugLocValue(*Asm, nullptr, Param.getValue(), DwarfExpr);
addBlock(*CallSiteDieParam, getDwarf5OrGNUAttr(dwarf::DW_AT_call_value),
DIE *DwarfCompileUnit::constructImportedEntityDIE(
const DIImportedEntity *Module) {
DIE *IMDie = DIE::get(DIEValueAllocator, (dwarf::Tag)Module->getTag());
insertDIE(Module, IMDie);
DIE *EntityDie;
auto *Entity = Module->getEntity();
if (auto *NS = dyn_cast<DINamespace>(Entity))
EntityDie = getOrCreateNameSpace(NS);
else if (auto *M = dyn_cast<DIModule>(Entity))
EntityDie = getOrCreateModule(M);
else if (auto *SP = dyn_cast<DISubprogram>(Entity))
EntityDie = getOrCreateSubprogramDIE(SP);
else if (auto *T = dyn_cast<DIType>(Entity))
EntityDie = getOrCreateTypeDIE(T);
else if (auto *GV = dyn_cast<DIGlobalVariable>(Entity))
EntityDie = getOrCreateGlobalVariableDIE(GV, {});
EntityDie = getDIE(Entity);
addSourceLine(*IMDie, Module->getLine(), Module->getFile());
addDIEEntry(*IMDie, dwarf::DW_AT_import, *EntityDie);
StringRef Name = Module->getName();
if (!Name.empty())
addString(*IMDie, dwarf::DW_AT_name, Name);
return IMDie;
void DwarfCompileUnit::finishSubprogramDefinition(const DISubprogram *SP) {
DIE *D = getDIE(SP);
if (DIE *AbsSPDIE = getAbstractSPDies().lookup(SP)) {
if (D)
// If this subprogram has an abstract definition, reference that
addDIEEntry(*D, dwarf::DW_AT_abstract_origin, *AbsSPDIE);
} else {
assert(D || includeMinimalInlineScopes());
if (D)
// And attach the attributes
applySubprogramAttributesToDefinition(SP, *D);
void DwarfCompileUnit::finishEntityDefinition(const DbgEntity *Entity) {
DbgEntity *AbsEntity = getExistingAbstractEntity(Entity->getEntity());
auto *Die = Entity->getDIE();
/// Label may be used to generate DW_AT_low_pc, so put it outside
/// if/else block.
const DbgLabel *Label = nullptr;
if (AbsEntity && AbsEntity->getDIE()) {
addDIEEntry(*Die, dwarf::DW_AT_abstract_origin, *AbsEntity->getDIE());
Label = dyn_cast<const DbgLabel>(Entity);
} else {
if (const DbgVariable *Var = dyn_cast<const DbgVariable>(Entity))
applyVariableAttributes(*Var, *Die);
else if ((Label = dyn_cast<const DbgLabel>(Entity)))
applyLabelAttributes(*Label, *Die);
llvm_unreachable("DbgEntity must be DbgVariable or DbgLabel.");
if (Label)
if (const auto *Sym = Label->getSymbol())
addLabelAddress(*Die, dwarf::DW_AT_low_pc, Sym);
DbgEntity *DwarfCompileUnit::getExistingAbstractEntity(const DINode *Node) {
auto &AbstractEntities = getAbstractEntities();
auto I = AbstractEntities.find(Node);
if (I != AbstractEntities.end())
return I->second.get();
return nullptr;
void DwarfCompileUnit::createAbstractEntity(const DINode *Node,
LexicalScope *Scope) {
assert(Scope && Scope->isAbstractScope());
auto &Entity = getAbstractEntities()[Node];
if (isa<const DILocalVariable>(Node)) {
Entity = std::make_unique<DbgVariable>(
cast<const DILocalVariable>(Node), nullptr /* IA */);;
DU->addScopeVariable(Scope, cast<DbgVariable>(Entity.get()));
} else if (isa<const DILabel>(Node)) {
Entity = std::make_unique<DbgLabel>(
cast<const DILabel>(Node), nullptr /* IA */);
DU->addScopeLabel(Scope, cast<DbgLabel>(Entity.get()));
void DwarfCompileUnit::emitHeader(bool UseOffsets) {
// Don't bother labeling the .dwo unit, as its offset isn't used.
if (!Skeleton && !DD->useSectionsAsReferences()) {
LabelBegin = Asm->createTempSymbol("cu_begin");
dwarf::UnitType UT = Skeleton ? dwarf::DW_UT_split_compile
: DD->useSplitDwarf() ? dwarf::DW_UT_skeleton
: dwarf::DW_UT_compile;
DwarfUnit::emitCommonHeader(UseOffsets, UT);
if (DD->getDwarfVersion() >= 5 && UT != dwarf::DW_UT_compile)
bool DwarfCompileUnit::hasDwarfPubSections() const {
switch (CUNode->getNameTableKind()) {
case DICompileUnit::DebugNameTableKind::None:
return false;
// Opting in to GNU Pubnames/types overrides the default to ensure these are
// generated for things like Gold's gdb_index generation.
case DICompileUnit::DebugNameTableKind::GNU:
return true;
case DICompileUnit::DebugNameTableKind::Default:
return DD->tuneForGDB() && !includeMinimalInlineScopes() &&
!CUNode->isDebugDirectivesOnly() &&
DD->getAccelTableKind() != AccelTableKind::Apple &&
DD->getDwarfVersion() < 5;
llvm_unreachable("Unhandled DICompileUnit::DebugNameTableKind enum");
/// addGlobalName - Add a new global name to the compile unit.
void DwarfCompileUnit::addGlobalName(StringRef Name, const DIE &Die,
const DIScope *Context) {
if (!hasDwarfPubSections())
std::string FullName = getParentContextString(Context) + Name.str();
GlobalNames[FullName] = &Die;
void DwarfCompileUnit::addGlobalNameForTypeUnit(StringRef Name,
const DIScope *Context) {
if (!hasDwarfPubSections())
std::string FullName = getParentContextString(Context) + Name.str();
// Insert, allowing the entry to remain as-is if it's already present
// This way the CU-level type DIE is preferred over the "can't describe this
// type as a unit offset because it's not really in the CU at all, it's only
// in a type unit"
GlobalNames.insert(std::make_pair(std::move(FullName), &getUnitDie()));
/// Add a new global type to the unit.
void DwarfCompileUnit::addGlobalType(const DIType *Ty, const DIE &Die,
const DIScope *Context) {
if (!hasDwarfPubSections())
std::string FullName = getParentContextString(Context) + Ty->getName().str();
GlobalTypes[FullName] = &Die;
void DwarfCompileUnit::addGlobalTypeUnitType(const DIType *Ty,
const DIScope *Context) {
if (!hasDwarfPubSections())
std::string FullName = getParentContextString(Context) + Ty->getName().str();
// Insert, allowing the entry to remain as-is if it's already present
// This way the CU-level type DIE is preferred over the "can't describe this
// type as a unit offset because it's not really in the CU at all, it's only
// in a type unit"
GlobalTypes.insert(std::make_pair(std::move(FullName), &getUnitDie()));
void DwarfCompileUnit::addVariableAddress(const DbgVariable &DV, DIE &Die,
MachineLocation Location) {
if (DV.hasComplexAddress())
addComplexAddress(DV, Die, dwarf::DW_AT_location, Location);
addAddress(Die, dwarf::DW_AT_location, Location);
/// Add an address attribute to a die based on the location provided.
void DwarfCompileUnit::addAddress(DIE &Die, dwarf::Attribute Attribute,
const MachineLocation &Location) {
DIELoc *Loc = new (DIEValueAllocator) DIELoc;
DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
if (Location.isIndirect())
DIExpressionCursor Cursor({});
const TargetRegisterInfo &TRI = *Asm->MF->getSubtarget().getRegisterInfo();
if (!DwarfExpr.addMachineRegExpression(TRI, Cursor, Location.getReg()))
// Now attach the location information to the DIE.
addBlock(Die, Attribute, DwarfExpr.finalize());
if (DwarfExpr.TagOffset)
addUInt(Die, dwarf::DW_AT_LLVM_tag_offset, dwarf::DW_FORM_data1,
/// Start with the address based on the location provided, and generate the
/// DWARF information necessary to find the actual variable given the extra
/// address information encoded in the DbgVariable, starting from the starting
/// location. Add the DWARF information to the die.
void DwarfCompileUnit::addComplexAddress(const DbgVariable &DV, DIE &Die,
dwarf::Attribute Attribute,
const MachineLocation &Location) {
DIELoc *Loc = new (DIEValueAllocator) DIELoc;
DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
const DIExpression *DIExpr = DV.getSingleExpression();
DwarfExpr.setLocation(Location, DIExpr);
DIExpressionCursor Cursor(DIExpr);
if (DIExpr->isEntryValue())
const TargetRegisterInfo &TRI = *Asm->MF->getSubtarget().getRegisterInfo();
if (!DwarfExpr.addMachineRegExpression(TRI, Cursor, Location.getReg()))
// Now attach the location information to the DIE.
addBlock(Die, Attribute, DwarfExpr.finalize());
if (DwarfExpr.TagOffset)
addUInt(Die, dwarf::DW_AT_LLVM_tag_offset, dwarf::DW_FORM_data1,
/// Add a Dwarf loclistptr attribute data and value.
void DwarfCompileUnit::addLocationList(DIE &Die, dwarf::Attribute Attribute,
unsigned Index) {
dwarf::Form Form = (DD->getDwarfVersion() >= 5)
? dwarf::DW_FORM_loclistx
: DD->getDwarfSectionOffsetForm();
Die.addValue(DIEValueAllocator, Attribute, Form, DIELocList(Index));
void DwarfCompileUnit::applyVariableAttributes(const DbgVariable &Var,
DIE &VariableDie) {
StringRef Name = Var.getName();
if (!Name.empty())
addString(VariableDie, dwarf::DW_AT_name, Name);
const auto *DIVar = Var.getVariable();
if (DIVar)
if (uint32_t AlignInBytes = DIVar->getAlignInBytes())
addUInt(VariableDie, dwarf::DW_AT_alignment, dwarf::DW_FORM_udata,
addSourceLine(VariableDie, DIVar);
addType(VariableDie, Var.getType());
if (Var.isArtificial())
addFlag(VariableDie, dwarf::DW_AT_artificial);
void DwarfCompileUnit::applyLabelAttributes(const DbgLabel &Label,
DIE &LabelDie) {
StringRef Name = Label.getName();
if (!Name.empty())
addString(LabelDie, dwarf::DW_AT_name, Name);
const auto *DILabel = Label.getLabel();
addSourceLine(LabelDie, DILabel);
/// Add a Dwarf expression attribute data and value.
void DwarfCompileUnit::addExpr(DIELoc &Die, dwarf::Form Form,
const MCExpr *Expr) {
Die.addValue(DIEValueAllocator, (dwarf::Attribute)0, Form, DIEExpr(Expr));
void DwarfCompileUnit::applySubprogramAttributesToDefinition(
const DISubprogram *SP, DIE &SPDie) {
auto *SPDecl = SP->getDeclaration();
auto *Context = SPDecl ? SPDecl->getScope() : SP->getScope();
applySubprogramAttributes(SP, SPDie, includeMinimalInlineScopes());
addGlobalName(SP->getName(), SPDie, Context);
bool DwarfCompileUnit::isDwoUnit() const {
return DD->useSplitDwarf() && Skeleton;
void DwarfCompileUnit::finishNonUnitTypeDIE(DIE& D, const DICompositeType *CTy) {
constructTypeDIE(D, CTy);
bool DwarfCompileUnit::includeMinimalInlineScopes() const {
return getCUNode()->getEmissionKind() == DICompileUnit::LineTablesOnly ||
(DD->useSplitDwarf() && !Skeleton);
void DwarfCompileUnit::addAddrTableBase() {
const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
MCSymbol *Label = DD->getAddressPool().getLabel();
DD->getDwarfVersion() >= 5 ? dwarf::DW_AT_addr_base
: dwarf::DW_AT_GNU_addr_base,
Label, TLOF.getDwarfAddrSection()->getBeginSymbol());
void DwarfCompileUnit::addBaseTypeRef(DIEValueList &Die, int64_t Idx) {
Die.addValue(DIEValueAllocator, (dwarf::Attribute)0, dwarf::DW_FORM_udata,
new (DIEValueAllocator) DIEBaseTypeRef(this, Idx));
void DwarfCompileUnit::createBaseTypeDIEs() {
// Insert the base_type DIEs directly after the CU so that their offsets will
// fit in the fixed size ULEB128 used inside the location expressions.
// Maintain order by iterating backwards and inserting to the front of CU
// child list.
for (auto &Btr : reverse(ExprRefedBaseTypes)) {
DIE &Die = getUnitDie().addChildFront(
DIE::get(DIEValueAllocator, dwarf::DW_TAG_base_type));
SmallString<32> Str;
addString(Die, dwarf::DW_AT_name,
Twine(dwarf::AttributeEncodingString(Btr.Encoding) +
"_" + Twine(Btr.BitSize)).toStringRef(Str));
addUInt(Die, dwarf::DW_AT_encoding, dwarf::DW_FORM_data1, Btr.Encoding);
addUInt(Die, dwarf::DW_AT_byte_size, None, Btr.BitSize / 8);
Btr.Die = &Die;