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//===-- DWARFDebugInfoEntry.cpp -------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "DWARFDebugInfoEntry.h"
#include <cassert>
#include <algorithm>
#include <limits>
#include <optional>
#include "LogChannelDWARF.h"
#include "lldb/Core/Module.h"
#include "lldb/Expression/DWARFExpression.h"
#include "lldb/Symbol/ObjectFile.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/DebugInfo/DWARF/DWARFAddressRange.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/FormatAdapters.h"
#include "llvm/Support/LEB128.h"
#include "DWARFCompileUnit.h"
#include "DWARFDebugAranges.h"
#include "DWARFDebugInfo.h"
#include "DWARFDeclContext.h"
#include "DWARFFormValue.h"
#include "DWARFUnit.h"
#include "SymbolFileDWARF.h"
#include "SymbolFileDWARFDwo.h"
using namespace lldb_private;
using namespace lldb_private::plugin::dwarf;
using namespace llvm::dwarf;
extern int g_verbose;
// Extract a debug info entry for a given DWARFUnit from the data
// starting at the offset in offset_ptr
bool DWARFDebugInfoEntry::Extract(const DWARFDataExtractor &data,
const DWARFUnit &unit,
lldb::offset_t *offset_ptr) {
m_offset = *offset_ptr;
auto report_error = [&](const char *fmt, const auto &...vals) {
unit.GetSymbolFileDWARF().GetObjectFile()->GetModule()->ReportError(
"[{0:x16}]: {1}, please file a bug and "
"attach the file at the start of this error message",
static_cast<uint64_t>(m_offset), llvm::formatv(fmt, vals...));
*offset_ptr = std::numeric_limits<lldb::offset_t>::max();
return false;
};
m_parent_idx = 0;
m_sibling_idx = 0;
const uint64_t abbr_idx = data.GetULEB128(offset_ptr);
if (abbr_idx > std::numeric_limits<uint16_t>::max())
return report_error("abbreviation code {0} too big", abbr_idx);
m_abbr_idx = abbr_idx;
if (m_abbr_idx == 0) {
m_tag = llvm::dwarf::DW_TAG_null;
m_has_children = false;
return true; // NULL debug tag entry
}
const auto *abbrevDecl = GetAbbreviationDeclarationPtr(&unit);
if (abbrevDecl == nullptr)
return report_error("invalid abbreviation code {0}", abbr_idx);
m_tag = abbrevDecl->getTag();
m_has_children = abbrevDecl->hasChildren();
// Skip all data in the .debug_info or .debug_types for the attributes
for (const auto &attribute : abbrevDecl->attributes()) {
if (DWARFFormValue::SkipValue(attribute.Form, data, offset_ptr, &unit))
continue;
return report_error("Unsupported DW_FORM_{1:x}", attribute.Form);
}
return true;
}
static llvm::Expected<llvm::DWARFAddressRangesVector>
GetRanges(DWARFUnit &unit, const DWARFFormValue &value) {
return (value.Form() == DW_FORM_rnglistx)
? unit.FindRnglistFromIndex(value.Unsigned())
: unit.FindRnglistFromOffset(value.Unsigned());
}
static void ExtractAttrAndFormValue(
const llvm::DWARFAbbreviationDeclaration::AttributeSpec &attr_spec,
dw_attr_t &attr, DWARFFormValue &form_value) {
attr = attr_spec.Attr;
form_value.FormRef() = attr_spec.Form;
if (attr_spec.isImplicitConst())
form_value.SetSigned(attr_spec.getImplicitConstValue());
}
// GetDIENamesAndRanges
//
// Gets the valid address ranges for a given DIE by looking for a
// DW_AT_low_pc/DW_AT_high_pc pair, DW_AT_entry_pc, or DW_AT_ranges attributes.
bool DWARFDebugInfoEntry::GetDIENamesAndRanges(
DWARFUnit *cu, const char *&name, const char *&mangled,
llvm::DWARFAddressRangesVector &ranges, std::optional<int> &decl_file,
std::optional<int> &decl_line, std::optional<int> &decl_column,
std::optional<int> &call_file, std::optional<int> &call_line,
std::optional<int> &call_column, DWARFExpressionList *frame_base) const {
dw_addr_t lo_pc = LLDB_INVALID_ADDRESS;
dw_addr_t hi_pc = LLDB_INVALID_ADDRESS;
std::vector<DWARFDIE> dies;
bool set_frame_base_loclist_addr = false;
SymbolFileDWARF &dwarf = cu->GetSymbolFileDWARF();
lldb::ModuleSP module = dwarf.GetObjectFile()->GetModule();
if (const auto *abbrevDecl = GetAbbreviationDeclarationPtr(cu)) {
const DWARFDataExtractor &data = cu->GetData();
lldb::offset_t offset = GetFirstAttributeOffset();
if (!data.ValidOffset(offset))
return false;
bool do_offset = false;
for (const auto &attribute : abbrevDecl->attributes()) {
DWARFFormValue form_value(cu);
dw_attr_t attr;
ExtractAttrAndFormValue(attribute, attr, form_value);
if (form_value.ExtractValue(data, &offset)) {
switch (attr) {
case DW_AT_low_pc:
lo_pc = form_value.Address();
if (do_offset)
hi_pc += lo_pc;
do_offset = false;
break;
case DW_AT_entry_pc:
lo_pc = form_value.Address();
break;
case DW_AT_high_pc:
if (form_value.Form() == DW_FORM_addr ||
form_value.Form() == DW_FORM_addrx ||
form_value.Form() == DW_FORM_GNU_addr_index) {
hi_pc = form_value.Address();
} else {
hi_pc = form_value.Unsigned();
if (lo_pc == LLDB_INVALID_ADDRESS)
do_offset = hi_pc != LLDB_INVALID_ADDRESS;
else
hi_pc += lo_pc; // DWARF 4 introduces <offset-from-lo-pc> to save
// on relocations
}
break;
case DW_AT_ranges:
if (llvm::Expected<llvm::DWARFAddressRangesVector> r =
GetRanges(*cu, form_value)) {
ranges = std::move(*r);
} else {
module->ReportError(
"[{0:x16}]: DIE has DW_AT_ranges({1} {2:x16}) attribute, but "
"range extraction failed ({3}), please file a bug "
"and attach the file at the start of this error message",
GetOffset(), llvm::dwarf::FormEncodingString(form_value.Form()),
form_value.Unsigned(), fmt_consume(r.takeError()));
}
break;
case DW_AT_name:
if (name == nullptr)
name = form_value.AsCString();
break;
case DW_AT_MIPS_linkage_name:
case DW_AT_linkage_name:
if (mangled == nullptr)
mangled = form_value.AsCString();
break;
case DW_AT_abstract_origin:
dies.push_back(form_value.Reference());
break;
case DW_AT_specification:
dies.push_back(form_value.Reference());
break;
case DW_AT_decl_file:
if (!decl_file)
decl_file = form_value.Unsigned();
break;
case DW_AT_decl_line:
if (!decl_line)
decl_line = form_value.Unsigned();
break;
case DW_AT_decl_column:
if (!decl_column)
decl_column = form_value.Unsigned();
break;
case DW_AT_call_file:
if (!call_file)
call_file = form_value.Unsigned();
break;
case DW_AT_call_line:
if (!call_line)
call_line = form_value.Unsigned();
break;
case DW_AT_call_column:
if (!call_column)
call_column = form_value.Unsigned();
break;
case DW_AT_frame_base:
if (frame_base) {
if (form_value.BlockData()) {
uint64_t block_offset =
form_value.BlockData() - data.GetDataStart();
uint64_t block_length = form_value.Unsigned();
*frame_base =
DWARFExpressionList(module,
DWARFExpression(DataExtractor(
data, block_offset, block_length)),
cu);
} else {
DataExtractor data = cu->GetLocationData();
const dw_offset_t offset = form_value.Unsigned();
if (data.ValidOffset(offset)) {
data = DataExtractor(data, offset, data.GetByteSize() - offset);
if (lo_pc != LLDB_INVALID_ADDRESS) {
assert(lo_pc >= cu->GetBaseAddress());
cu->ParseDWARFLocationList(data, *frame_base);
frame_base->SetFuncFileAddress(lo_pc);
} else
set_frame_base_loclist_addr = true;
}
}
}
break;
default:
break;
}
}
}
}
if (ranges.empty() && lo_pc != LLDB_INVALID_ADDRESS) {
lldb::addr_t range_hi_pc =
(hi_pc != LLDB_INVALID_ADDRESS && hi_pc > lo_pc) ? hi_pc : lo_pc;
ranges.emplace_back(lo_pc, range_hi_pc);
}
if (set_frame_base_loclist_addr && !ranges.empty()) {
dw_addr_t file_addr = ranges.begin()->LowPC;
assert(file_addr >= cu->GetBaseAddress());
frame_base->SetFuncFileAddress(file_addr);
}
if (ranges.empty() || name == nullptr || mangled == nullptr) {
for (const DWARFDIE &die : dies) {
if (die) {
die.GetDIE()->GetDIENamesAndRanges(die.GetCU(), name, mangled, ranges,
decl_file, decl_line, decl_column,
call_file, call_line, call_column);
}
}
}
return !ranges.empty();
}
/// Helper for the public \ref DWARFDebugInfoEntry::GetAttributes API.
/// Adds all attributes of the DIE at the top of the \c worklist to the
/// \c attributes list. Specifcations and abstract origins are added
/// to the \c worklist if the referenced DIE has not been seen before.
static bool GetAttributes(llvm::SmallVectorImpl<DWARFDIE> &worklist,
llvm::SmallSet<DWARFDebugInfoEntry const *, 3> &seen,
DWARFAttributes &attributes) {
assert(!worklist.empty() && "Need at least one DIE to visit.");
assert(seen.size() >= 1 &&
"Need to have seen at least the currently visited entry.");
DWARFDIE current = worklist.pop_back_val();
const auto *cu = current.GetCU();
assert(cu);
const auto *entry = current.GetDIE();
assert(entry);
const auto *abbrevDecl =
entry->GetAbbreviationDeclarationPtr(current.GetCU());
if (!abbrevDecl)
return false;
const DWARFDataExtractor &data = cu->GetData();
lldb::offset_t offset = current.GetDIE()->GetFirstAttributeOffset();
const bool is_first_die = seen.size() == 1;
for (const auto &attribute : abbrevDecl->attributes()) {
DWARFFormValue form_value(cu);
dw_attr_t attr;
ExtractAttrAndFormValue(attribute, attr, form_value);
// If we are tracking down DW_AT_specification or DW_AT_abstract_origin
// attributes, the depth will be non-zero. We need to omit certain
// attributes that don't make sense.
switch (attr) {
case DW_AT_sibling:
case DW_AT_declaration:
if (!is_first_die) {
// This attribute doesn't make sense when combined with the DIE that
// references this DIE. We know a DIE is referencing this DIE because
// we've visited more than one DIE already.
break;
}
[[fallthrough]];
default:
attributes.Append(form_value, offset, attr);
break;
}
if (attr == DW_AT_specification || attr == DW_AT_abstract_origin) {
if (form_value.ExtractValue(data, &offset)) {
if (DWARFDIE spec_die = form_value.Reference()) {
if (seen.insert(spec_die.GetDIE()).second)
worklist.push_back(spec_die);
}
}
} else {
const dw_form_t form = form_value.Form();
std::optional<uint8_t> fixed_skip_size =
DWARFFormValue::GetFixedSize(form, cu);
if (fixed_skip_size)
offset += *fixed_skip_size;
else
DWARFFormValue::SkipValue(form, data, &offset, cu);
}
}
return true;
}
DWARFAttributes DWARFDebugInfoEntry::GetAttributes(const DWARFUnit *cu,
Recurse recurse) const {
// FIXME: use ElaboratingDIEIterator to follow specifications/abstract origins
// instead of maintaining our own worklist/seen list.
DWARFAttributes attributes;
llvm::SmallVector<DWARFDIE, 3> worklist;
worklist.emplace_back(cu, this);
// Keep track if DIEs already seen to prevent infinite recursion.
// Value of '3' was picked for the same reason that
// DWARFDie::findRecursively does.
llvm::SmallSet<DWARFDebugInfoEntry const *, 3> seen;
seen.insert(this);
do {
if (!::GetAttributes(worklist, seen, attributes)) {
attributes.Clear();
break;
}
} while (!worklist.empty() && recurse == Recurse::yes);
return attributes;
}
// GetAttributeValue
//
// Get the value of an attribute and return the .debug_info or .debug_types
// offset of the attribute if it was properly extracted into form_value,
// or zero if we fail since an offset of zero is invalid for an attribute (it
// would be a compile unit header).
dw_offset_t DWARFDebugInfoEntry::GetAttributeValue(
const DWARFUnit *cu, const dw_attr_t attr, DWARFFormValue &form_value,
dw_offset_t *end_attr_offset_ptr, bool check_elaborating_dies) const {
if (const auto *abbrevDecl = GetAbbreviationDeclarationPtr(cu)) {
std::optional<uint32_t> attr_idx = abbrevDecl->findAttributeIndex(attr);
if (attr_idx) {
const DWARFDataExtractor &data = cu->GetData();
lldb::offset_t offset = GetFirstAttributeOffset();
uint32_t idx = 0;
while (idx < *attr_idx)
DWARFFormValue::SkipValue(abbrevDecl->getFormByIndex(idx++), data,
&offset, cu);
const dw_offset_t attr_offset = offset;
form_value.SetUnit(cu);
form_value.SetForm(abbrevDecl->getFormByIndex(idx));
if (abbrevDecl->getAttrIsImplicitConstByIndex(idx))
form_value.SetValue(abbrevDecl->getAttrImplicitConstValueByIndex(idx));
if (form_value.ExtractValue(data, &offset)) {
if (end_attr_offset_ptr)
*end_attr_offset_ptr = offset;
return attr_offset;
}
}
}
if (check_elaborating_dies) {
for (dw_attr_t elaborating_attr :
{DW_AT_specification, DW_AT_abstract_origin, DW_AT_signature}) {
if (!GetAttributeValue(cu, elaborating_attr, form_value))
continue;
DWARFDIE die = form_value.Reference();
if (!die)
continue;
dw_offset_t die_offset = die.GetDIE()->GetAttributeValue(
die.GetCU(), attr, form_value, end_attr_offset_ptr, false);
if (die_offset)
return die_offset;
}
}
return 0;
}
// GetAttributeValueAsString
//
// Get the value of an attribute as a string return it. The resulting pointer
// to the string data exists within the supplied SymbolFileDWARF and will only
// be available as long as the SymbolFileDWARF is still around and it's content
// doesn't change.
const char *DWARFDebugInfoEntry::GetAttributeValueAsString(
const DWARFUnit *cu, const dw_attr_t attr, const char *fail_value,
bool check_elaborating_dies) const {
DWARFFormValue form_value;
if (GetAttributeValue(cu, attr, form_value, nullptr, check_elaborating_dies))
return form_value.AsCString();
return fail_value;
}
// GetAttributeValueAsUnsigned
//
// Get the value of an attribute as unsigned and return it.
uint64_t DWARFDebugInfoEntry::GetAttributeValueAsUnsigned(
const DWARFUnit *cu, const dw_attr_t attr, uint64_t fail_value,
bool check_elaborating_dies) const {
DWARFFormValue form_value;
if (GetAttributeValue(cu, attr, form_value, nullptr, check_elaborating_dies))
return form_value.Unsigned();
return fail_value;
}
std::optional<uint64_t>
DWARFDebugInfoEntry::GetAttributeValueAsOptionalUnsigned(
const DWARFUnit *cu, const dw_attr_t attr,
bool check_elaborating_dies) const {
DWARFFormValue form_value;
if (GetAttributeValue(cu, attr, form_value, nullptr, check_elaborating_dies))
return form_value.Unsigned();
return std::nullopt;
}
// GetAttributeValueAsReference
//
// Get the value of an attribute as reference and fix up and compile unit
// relative offsets as needed.
DWARFDIE DWARFDebugInfoEntry::GetAttributeValueAsReference(
const DWARFUnit *cu, const dw_attr_t attr,
bool check_elaborating_dies) const {
DWARFFormValue form_value;
if (GetAttributeValue(cu, attr, form_value, nullptr, check_elaborating_dies))
return form_value.Reference();
return {};
}
uint64_t DWARFDebugInfoEntry::GetAttributeValueAsAddress(
const DWARFUnit *cu, const dw_attr_t attr, uint64_t fail_value,
bool check_elaborating_dies) const {
DWARFFormValue form_value;
if (GetAttributeValue(cu, attr, form_value, nullptr, check_elaborating_dies))
return form_value.Address();
return fail_value;
}
// GetAttributeHighPC
//
// Get the hi_pc, adding hi_pc to lo_pc when specified as an <offset-from-low-
// pc>.
//
// Returns the hi_pc or fail_value.
dw_addr_t
DWARFDebugInfoEntry::GetAttributeHighPC(const DWARFUnit *cu, dw_addr_t lo_pc,
uint64_t fail_value,
bool check_elaborating_dies) const {
DWARFFormValue form_value;
if (GetAttributeValue(cu, DW_AT_high_pc, form_value, nullptr,
check_elaborating_dies)) {
dw_form_t form = form_value.Form();
if (form == DW_FORM_addr || form == DW_FORM_addrx ||
form == DW_FORM_GNU_addr_index)
return form_value.Address();
// DWARF4 can specify the hi_pc as an <offset-from-lowpc>
return lo_pc + form_value.Unsigned();
}
return fail_value;
}
// GetAttributeAddressRange
//
// Get the lo_pc and hi_pc, adding hi_pc to lo_pc when specified as an <offset-
// from-low-pc>.
//
// Returns true or sets lo_pc and hi_pc to fail_value.
bool DWARFDebugInfoEntry::GetAttributeAddressRange(
const DWARFUnit *cu, dw_addr_t &lo_pc, dw_addr_t &hi_pc,
uint64_t fail_value, bool check_elaborating_dies) const {
lo_pc = GetAttributeValueAsAddress(cu, DW_AT_low_pc, fail_value,
check_elaborating_dies);
if (lo_pc != fail_value) {
hi_pc = GetAttributeHighPC(cu, lo_pc, fail_value, check_elaborating_dies);
if (hi_pc != fail_value)
return true;
}
lo_pc = fail_value;
hi_pc = fail_value;
return false;
}
llvm::Expected<llvm::DWARFAddressRangesVector>
DWARFDebugInfoEntry::GetAttributeAddressRanges(
DWARFUnit *cu, bool check_hi_lo_pc, bool check_elaborating_dies) const {
DWARFFormValue form_value;
if (GetAttributeValue(cu, DW_AT_ranges, form_value))
return GetRanges(*cu, form_value);
if (check_hi_lo_pc) {
dw_addr_t lo_pc = LLDB_INVALID_ADDRESS;
dw_addr_t hi_pc = LLDB_INVALID_ADDRESS;
if (GetAttributeAddressRange(cu, lo_pc, hi_pc, LLDB_INVALID_ADDRESS,
check_elaborating_dies) &&
lo_pc < hi_pc)
return llvm::DWARFAddressRangesVector{{lo_pc, hi_pc}};
}
return llvm::createStringError("DIE has no address range information");
}
// GetName
//
// Get value of the DW_AT_name attribute and return it if one exists, else
// return NULL.
const char *DWARFDebugInfoEntry::GetName(const DWARFUnit *cu) const {
return GetAttributeValueAsString(cu, DW_AT_name, nullptr, true);
}
// GetMangledName
//
// Get value of the DW_AT_MIPS_linkage_name attribute and return it if one
// exists, else return the value of the DW_AT_name attribute
const char *
DWARFDebugInfoEntry::GetMangledName(const DWARFUnit *cu,
bool substitute_name_allowed) const {
const char *name = nullptr;
name = GetAttributeValueAsString(cu, DW_AT_MIPS_linkage_name, nullptr, true);
if (name)
return name;
name = GetAttributeValueAsString(cu, DW_AT_linkage_name, nullptr, true);
if (name)
return name;
if (!substitute_name_allowed)
return nullptr;
name = GetAttributeValueAsString(cu, DW_AT_name, nullptr, true);
return name;
}
// GetPubname
//
// Get value the name for a DIE as it should appear for a .debug_pubnames or
// .debug_pubtypes section.
const char *DWARFDebugInfoEntry::GetPubname(const DWARFUnit *cu) const {
const char *name = nullptr;
if (!cu)
return name;
name = GetAttributeValueAsString(cu, DW_AT_MIPS_linkage_name, nullptr, true);
if (name)
return name;
name = GetAttributeValueAsString(cu, DW_AT_linkage_name, nullptr, true);
if (name)
return name;
name = GetAttributeValueAsString(cu, DW_AT_name, nullptr, true);
return name;
}
/// This function is builds a table very similar to the standard .debug_aranges
/// table, except that the actual DIE offset for the function is placed in the
/// table instead of the compile unit offset.
void DWARFDebugInfoEntry::BuildFunctionAddressRangeTable(
DWARFUnit *cu, DWARFDebugAranges *debug_aranges) const {
Log *log = GetLog(DWARFLog::DebugInfo);
if (m_tag) {
// Subprogram forward declarations don't have
// DW_AT_ranges/DW_AT_low_pc/DW_AT_high_pc attributes, so don't even try
// getting address range information for them.
if (m_tag == DW_TAG_subprogram &&
!GetAttributeValueAsOptionalUnsigned(cu, DW_AT_declaration)) {
if (llvm::Expected<llvm::DWARFAddressRangesVector> ranges =
GetAttributeAddressRanges(cu, /*check_hi_lo_pc=*/true)) {
for (const auto &r : *ranges)
debug_aranges->AppendRange(GetOffset(), r.LowPC, r.HighPC);
} else {
LLDB_LOG_ERROR(log, ranges.takeError(), "DIE({1:x}): {0}", GetOffset());
}
}
const DWARFDebugInfoEntry *child = GetFirstChild();
while (child) {
child->BuildFunctionAddressRangeTable(cu, debug_aranges);
child = child->GetSibling();
}
}
}
lldb::offset_t DWARFDebugInfoEntry::GetFirstAttributeOffset() const {
return GetOffset() + llvm::getULEB128Size(m_abbr_idx);
}
const llvm::DWARFAbbreviationDeclaration *
DWARFDebugInfoEntry::GetAbbreviationDeclarationPtr(const DWARFUnit *cu) const {
if (!cu)
return nullptr;
const llvm::DWARFAbbreviationDeclarationSet *abbrev_set =
cu->GetAbbreviations();
if (!abbrev_set)
return nullptr;
return abbrev_set->getAbbreviationDeclaration(m_abbr_idx);
}
bool DWARFDebugInfoEntry::IsGlobalOrStaticScopeVariable() const {
if (Tag() != DW_TAG_variable && Tag() != DW_TAG_member)
return false;
const DWARFDebugInfoEntry *parent_die = GetParent();
while (parent_die != nullptr) {
switch (parent_die->Tag()) {
case DW_TAG_subprogram:
case DW_TAG_lexical_block:
case DW_TAG_inlined_subroutine:
return false;
case DW_TAG_compile_unit:
case DW_TAG_partial_unit:
return true;
default:
break;
}
parent_die = parent_die->GetParent();
}
return false;
}
bool DWARFDebugInfoEntry::operator==(const DWARFDebugInfoEntry &rhs) const {
return m_offset == rhs.m_offset && m_parent_idx == rhs.m_parent_idx &&
m_sibling_idx == rhs.m_sibling_idx &&
m_abbr_idx == rhs.m_abbr_idx && m_has_children == rhs.m_has_children &&
m_tag == rhs.m_tag;
}
bool DWARFDebugInfoEntry::operator!=(const DWARFDebugInfoEntry &rhs) const {
return !(*this == rhs);
}