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DWARF: Implement DW_AT_signature lookup for type unit support 

Summary:
This patch implements the main feature of type units. When completing a
type, if we encounter a DW_AT_signature attribute, we use it's value to
lookup the complete definition of the type in the relevant type unit.

To enable this lookup, we build up a map of all type units in a symbol
file when parsing the units. Then we consult this map when resolving the
DW_AT_signature attribute.

I include add a couple of tests which exercise the type lookup feature,
including one that ensure we do something reasonable in case we fail to
lookup the type.

A lot of the ideas in this patch have been taken from D32167 and D61505.

Reviewers: clayborg, JDevlieghere, aprantl, alexshap

Subscribers: mgrang, lldb-commits

Differential Revision: https://reviews.llvm.org/D62246

llvm-svn: 361603
This commit is contained in:
Pavel Labath 2019-05-24 08:11:12 +00:00
parent 8ac0bc9832
commit f750842c8b
14 changed files with 258 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
lldb/lit/SymbolFile/DWARF/Inputs/debug-types-basic.cpp
View File

@ -1,13 +1,15 @@
enum E { e1, e2, e3 };
enum class EC { e1, e2, e3 };
struct A {
int i;
long l;
float f;
double d;
E e;
EC ec;
};
enum E { e1, e2, e3 };
enum class EC { e1, e2, e3 };
extern constexpr A a{42, 47l, 4.2f, 4.7};
extern constexpr A a{42, 47l, 4.2f, 4.7, e1, EC::e3};
extern constexpr E e(e2);
extern constexpr EC ec(EC::e2);

8
lldb/lit/SymbolFile/DWARF/Inputs/debug-types-expressions.cpp
View File

@ -11,11 +11,19 @@ struct B: public A {
namespace ns {
struct A {
int i = 147;
::A getA();
A();
};
A::A() = default;
::A A::getA() {
::A a;
a.i = i - 1;
return a;
}
} // namespace ns
int foo(A *a) {
return a->f();
}

8
lldb/lit/SymbolFile/DWARF/debug-types-basic.test
View File

@ -19,6 +19,8 @@ type lookup A
# CHECK-NEXT: long l;
# CHECK-NEXT: float f;
# CHECK-NEXT: double d;
# CHECK-NEXT: E e;
# CHECK-NEXT: EC ec;
# CHECK-NEXT: }
type lookup E
@ -44,3 +46,9 @@ print (E) 1
print (EC) 1
# CHECK-LABEL: print (EC) 1
# CHECK: (EC) $1 = e2
target variable a e ec
# CHECK-LABEL: target variable a e ec
# CHECK: (const A) a = (i = 42, l = 47, f = 4.{{[12].*}}, d = 4.{{[67].*}}, e = e1, ec = e3)
# CHECK: (const E) e = e2
# CHECK: (const EC) ec = e2

15
lldb/lit/SymbolFile/DWARF/debug-types-expressions.test
View File

@ -19,6 +19,13 @@ frame variable a
# CHECK-LABEL: frame variable a
# CHECK: (B *) a =
frame variable *a
# CHECK-LABEL: frame variable *a
# CHECK: (B) *a = {
# CHECK-NEXT: A = (i = 47)
# CHECK-NEXT: j = 42
# CHECK-NEXT: }
print a->f()
# CHECK-LABEL: print a->f()
# CHECK: (int) $0 = 47
@ -26,3 +33,11 @@ print a->f()
print ns::A()
# CHECK-LABEL: print ns::A()
# CHECK: (ns::A) $1 = (i = 147)
print ns::A().i + a->i
# CHECK-LABEL: print ns::A().i + a->i
# CHECK: (int) $2 = 194
print ns::A().getA()
# CHECK-LABEL: ns::A().getA()
# CHECK: (A) $3 = (i = 146)

26
lldb/lit/SymbolFile/DWARF/debug-types-missing-signature.test Normal file
View File

@ -0,0 +1,26 @@
Create a dangling DW_AT_signature reference by stripping the debug_types
section, and make sure lldb does something reasonable.
RUN: %clangxx -target x86_64-pc-linux %S/Inputs/debug-types-basic.cpp \
RUN: -g -gdwarf-4 -fdebug-types-section -c -o %t.o
RUN: llvm-objcopy --remove-section=.debug_types %t.o %t
RUN: %lldb %t -b -o "type lookup A" | FileCheck --check-prefix=LOOKUPA %s
LOOKUPA: no type was found matching 'A'
RUN: %lldb %t -b -o "type lookup E" | FileCheck --check-prefix=LOOKUPE %s
LOOKUPE: no type was found matching 'E'
RUN: %lldb %t -b -o "type lookup EC" | FileCheck --check-prefix=LOOKUPEC %s
LOOKUPEC: no type was found matching 'EC'
RUN: %lldb %t -b -o "print (E) 1" 2>&1 | FileCheck --check-prefix=PRINTE %s
PRINTE: use of undeclared identifier 'E'
RUN: %lldb %t -b -o "print (EC) 1" 2>&1 | FileCheck --check-prefix=PRINTEC %s
PRINTEC: use of undeclared identifier 'EC'
RUN: %lldb %t -b -o "target variable a e ec" | FileCheck --check-prefix=VARS %s
VARS: (const (anonymous struct)) a = {}
VARS: (const (anonymous enum)) e = 1
VARS: (const (anonymous enum)) ec = 1

115
lldb/lit/SymbolFile/DWARF/debug-types-signature-loop.s Normal file
View File

@ -0,0 +1,115 @@
# REQUIRES: lld
# RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux -o %t.o %s
# RUN: ld.lld %t.o -o %t
# RUN: %lldb %t -o "target variable e" -b | FileCheck %s
# CHECK: e = <could not resolve type>
.type e,@object # @e
.section .rodata,"a",@progbits
.globl e
.p2align 2
e:
.long 0 # 0x0
.size e, 4
.Lstr_offsets_base0:
.section .debug_str,"MS",@progbits,1
.Linfo_string0:
.asciz "Hand-written DWARF"
.Linfo_string1:
.asciz "a.cpp"
.Linfo_string3:
.asciz "e"
.Linfo_string4:
.asciz "unsigned int"
.Linfo_string5:
.asciz "e1"
.Linfo_string6:
.asciz "E"
.section .debug_abbrev,"",@progbits
.byte 1 # Abbreviation Code
.byte 65 # DW_TAG_type_unit
.byte 1 # DW_CHILDREN_yes
.byte 19 # DW_AT_language
.byte 5 # DW_FORM_data2
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 5 # Abbreviation Code
.byte 17 # DW_TAG_compile_unit
.byte 1 # DW_CHILDREN_yes
.byte 37 # DW_AT_producer
.byte 14 # DW_FORM_strp
.byte 19 # DW_AT_language
.byte 5 # DW_FORM_data2
.byte 3 # DW_AT_name
.byte 14 # DW_FORM_strp
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 6 # Abbreviation Code
.byte 52 # DW_TAG_variable
.byte 0 # DW_CHILDREN_no
.byte 3 # DW_AT_name
.byte 14 # DW_FORM_strp
.byte 73 # DW_AT_type
.byte 19 # DW_FORM_ref4
.byte 2 # DW_AT_location
.byte 24 # DW_FORM_exprloc
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 8 # Abbreviation Code
.byte 4 # DW_TAG_enumeration_type
.byte 0 # DW_CHILDREN_no
.byte 60 # DW_AT_declaration
.byte 25 # DW_FORM_flag_present
.byte 105 # DW_AT_signature
.byte 32 # DW_FORM_ref_sig8
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 0 # EOM(3)
.section .debug_info,"",@progbits
.Ltu_begin0:
.long .Ldebug_info_end0-.Ldebug_info_start0 # Length of Unit
.Ldebug_info_start0:
.short 5 # DWARF version number
.byte 2 # DWARF Unit Type
.byte 8 # Address Size (in bytes)
.long .debug_abbrev # Offset Into Abbrev. Section
.quad 5390450678491038984 # Type Signature
.long .LE-.Ltu_begin0 # Type DIE Offset
.byte 1 # Abbrev [1] 0x18:0x1d DW_TAG_type_unit
.short 4 # DW_AT_language
.LE:
.byte 8 # Abbrev [8] 0x23:0xd DW_TAG_enumeration_type
# DW_AT_declaration
.quad 5390450678491038984 # DW_AT_signature
.Lbase:
.byte 0 # End Of Children Mark
.Ldebug_info_end0:
.Lcu_begin0:
.long .Ldebug_info_end1-.Ldebug_info_start1 # Length of Unit
.Ldebug_info_start1:
.short 5 # DWARF version number
.byte 1 # DWARF Unit Type
.byte 8 # Address Size (in bytes)
.long .debug_abbrev # Offset Into Abbrev. Section
.byte 5 # Abbrev [5] 0xc:0x2c DW_TAG_compile_unit
.long .Linfo_string0 # DW_AT_producer
.short 4 # DW_AT_language
.long .Linfo_string1 # DW_AT_name
.byte 6 # Abbrev [6] 0x1e:0xb DW_TAG_variable
.long .Linfo_string3 # DW_AT_name
.long .LE_sig-.Lcu_begin0 # DW_AT_type
.byte 9 # DW_AT_location
.byte 3
.quad e
.LE_sig:
.byte 8 # Abbrev [8] 0x2e:0x9 DW_TAG_enumeration_type
# DW_AT_declaration
.quad 5390450678491038984 # DW_AT_signature
.byte 0 # End Of Children Mark
.Ldebug_info_end1:

32
lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
View File

@ -237,7 +237,6 @@ TypeSP DWARFASTParserClang::ParseTypeFromDWARF(const SymbolContext &sc,
AccessType accessibility = eAccessNone;
if (!die)
return nullptr;
SymbolFileDWARF *dwarf = die.GetDWARF();
if (log) {
DWARFDIE context_die;
@ -252,11 +251,27 @@ TypeSP DWARFASTParserClang::ParseTypeFromDWARF(const SymbolContext &sc,
die.GetTagAsCString(), die.GetName());
}
Type *type_ptr = dwarf->GetDIEToType().lookup(die.GetDIE());
if (type_ptr == DIE_IS_BEING_PARSED)
return nullptr;
if (type_ptr)
return type_ptr->shared_from_this();
// Set a bit that lets us know that we are currently parsing this
dwarf->GetDIEToType()[die.GetDIE()] = DIE_IS_BEING_PARSED;
if (DWARFDIE signature_die =
die.GetAttributeValueAsReferenceDIE(DW_AT_signature)) {
if (TypeSP type_sp =
ParseTypeFromDWARF(sc, signature_die, log, type_is_new_ptr)) {
dwarf->GetDIEToType()[die.GetDIE()] = type_sp.get();
if (clang::DeclContext *decl_ctx =
GetCachedClangDeclContextForDIE(signature_die))
LinkDeclContextToDIE(decl_ctx, die);
return type_sp;
}
return nullptr;
}
TypeList *type_list = dwarf->GetTypeList();
if (type_is_new_ptr)
@ -289,9 +304,6 @@ TypeSP DWARFASTParserClang::ParseTypeFromDWARF(const SymbolContext &sc,
case DW_TAG_restrict_type:
case DW_TAG_volatile_type:
case DW_TAG_unspecified_type: {
// Set a bit that lets us know that we are currently parsing this
dwarf->GetDIEToType()[die.GetDIE()] = DIE_IS_BEING_PARSED;
const size_t num_attributes = die.GetAttributes(attributes);
uint32_t encoding = 0;
DWARFFormValue encoding_uid;
@ -540,9 +552,6 @@ TypeSP DWARFASTParserClang::ParseTypeFromDWARF(const SymbolContext &sc,
case DW_TAG_structure_type:
case DW_TAG_union_type:
case DW_TAG_class_type: {
// Set a bit that lets us know that we are currently parsing this
dwarf->GetDIEToType()[die.GetDIE()] = DIE_IS_BEING_PARSED;
LanguageType class_language = eLanguageTypeUnknown;
bool is_complete_objc_class = false;
size_t calling_convention = llvm::dwarf::CallingConvention::DW_CC_normal;
@ -974,9 +983,6 @@ TypeSP DWARFASTParserClang::ParseTypeFromDWARF(const SymbolContext &sc,
} break;
case DW_TAG_enumeration_type: {
// Set a bit that lets us know that we are currently parsing this
dwarf->GetDIEToType()[die.GetDIE()] = DIE_IS_BEING_PARSED;
bool is_scoped = false;
DWARFFormValue encoding_form;
@ -1136,9 +1142,6 @@ TypeSP DWARFASTParserClang::ParseTypeFromDWARF(const SymbolContext &sc,
case DW_TAG_inlined_subroutine:
case DW_TAG_subprogram:
case DW_TAG_subroutine_type: {
// Set a bit that lets us know that we are currently parsing this
dwarf->GetDIEToType()[die.GetDIE()] = DIE_IS_BEING_PARSED;
DWARFFormValue type_die_form;
bool is_variadic = false;
bool is_inline = false;
@ -1658,9 +1661,6 @@ TypeSP DWARFASTParserClang::ParseTypeFromDWARF(const SymbolContext &sc,
} break;
case DW_TAG_array_type: {
// Set a bit that lets us know that we are currently parsing this
dwarf->GetDIEToType()[die.GetDIE()] = DIE_IS_BEING_PARSED;
DWARFFormValue type_die_form;
uint32_t byte_stride = 0;
uint32_t bit_stride = 0;

35
lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfo.cpp
View File

@ -15,6 +15,7 @@
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Utility/RegularExpression.h"
#include "lldb/Utility/Stream.h"
#include "llvm/Support/Casting.h"
#include "DWARFCompileUnit.h"
#include "DWARFContext.h"
@ -74,12 +75,14 @@ llvm::Expected<DWARFDebugAranges &> DWARFDebugInfo::GetCompileUnitAranges() {
return *m_cu_aranges_up;
}
void Parse(SymbolFileDWARF *dwarf, const DWARFDataExtractor &data,
DIERef::Section section, std::vector<DWARFUnitSP> &units) {
void DWARFDebugInfo::ParseUnitsFor(DIERef::Section section) {
DWARFDataExtractor data = section == DIERef::Section::DebugTypes
? m_context.getOrLoadDebugTypesData()
: m_context.getOrLoadDebugInfoData();
lldb::offset_t offset = 0;
while (data.ValidOffset(offset)) {
llvm::Expected<DWARFUnitSP> unit_sp =
DWARFUnit::extract(dwarf, units.size(), data, section, &offset);
llvm::Expected<DWARFUnitSP> unit_sp = DWARFUnit::extract(
m_dwarf2Data, m_units.size(), data, section, &offset);
if (!unit_sp) {
// FIXME: Propagate this error up.
@ -89,10 +92,13 @@ void Parse(SymbolFileDWARF *dwarf, const DWARFDataExtractor &data,
// If it didn't return an error, then it should be returning a valid Unit.
assert(*unit_sp);
units.push_back(*unit_sp);
m_units.push_back(*unit_sp);
offset = (*unit_sp)->GetNextUnitOffset();
if (auto *type_unit = llvm::dyn_cast<DWARFTypeUnit>(unit_sp->get())) {
m_type_hash_to_unit_index.emplace_back(type_unit->GetTypeHash(),
unit_sp.get()->GetID());
}
}
}
@ -102,10 +108,9 @@ void DWARFDebugInfo::ParseUnitHeadersIfNeeded() {
if (!m_dwarf2Data)
return;
Parse(m_dwarf2Data, m_context.getOrLoadDebugInfoData(),
DIERef::Section::DebugInfo, m_units);
Parse(m_dwarf2Data, m_context.getOrLoadDebugTypesData(),
DIERef::Section::DebugTypes, m_units);
ParseUnitsFor(DIERef::Section::DebugInfo);
ParseUnitsFor(DIERef::Section::DebugTypes);
llvm::sort(m_type_hash_to_unit_index, llvm::less_first());
}
size_t DWARFDebugInfo::GetNumUnits() {
@ -169,6 +174,14 @@ DWARFDebugInfo::GetUnitContainingDIEOffset(DIERef::Section section,
return result;
}
DWARFTypeUnit *DWARFDebugInfo::GetTypeUnitForHash(uint64_t hash) {
auto pos = llvm::lower_bound(m_type_hash_to_unit_index,
std::make_pair(hash, 0u), llvm::less_first());
if (pos == m_type_hash_to_unit_index.end() || pos->first != hash)
return nullptr;
return llvm::cast<DWARFTypeUnit>(GetUnitAtIndex(pos->second));
}
DWARFDIE
DWARFDebugInfo::GetDIEForDIEOffset(DIERef::Section section,
dw_offset_t die_offset) {

6
lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfo.h
View File

@ -13,6 +13,7 @@
#include <vector>
#include "DWARFDIE.h"
#include "DWARFTypeUnit.h"
#include "DWARFUnit.h"
#include "SymbolFileDWARF.h"
#include "lldb/Core/STLUtils.h"
@ -46,6 +47,7 @@ public:
DWARFUnit *GetUnitContainingDIEOffset(DIERef::Section section,
dw_offset_t die_offset);
DWARFUnit *GetUnit(const DIERef &die_ref);
DWARFTypeUnit *GetTypeUnitForHash(uint64_t hash);
DWARFDIE GetDIEForDIEOffset(DIERef::Section section,
dw_offset_t die_offset);
DWARFDIE GetDIE(const DIERef &die_ref);
@ -69,11 +71,15 @@ protected:
std::unique_ptr<DWARFDebugAranges>
m_cu_aranges_up; // A quick address to compile unit table
std::vector<std::pair<uint64_t, uint32_t>> m_type_hash_to_unit_index;
private:
// All parsing needs to be done partially any managed by this class as
// accessors are called.
void ParseUnitHeadersIfNeeded();
void ParseUnitsFor(DIERef::Section section);
uint32_t FindUnitIndex(DIERef::Section section, dw_offset_t offset);
DISALLOW_COPY_AND_ASSIGN(DWARFDebugInfo);

8
lldb/source/Plugins/SymbolFile/DWARF/DWARFFormValue.cpp
View File

@ -585,6 +585,14 @@ DWARFDIE DWARFFormValue::Reference() const {
return ref_cu->GetDIE(value);
}
case DW_FORM_ref_sig8: {
DWARFTypeUnit *tu =
m_unit->GetSymbolFileDWARF()->DebugInfo()->GetTypeUnitForHash(value);
if (!tu)
return {};
return tu->GetDIE(tu->GetTypeOffset());
}
default:
return {};
}

1
lldb/source/Plugins/SymbolFile/DWARF/DWARFTypeUnit.cpp
View File

@ -14,7 +14,6 @@
using namespace lldb;
using namespace lldb_private;
void DWARFTypeUnit::Dump(Stream *s) const {
s->Printf("0x%8.8x: Type Unit: length = 0x%8.8x, version = 0x%4.4x, "
"abbr_offset = 0x%8.8x, addr_size = 0x%2.2x (next CU at "

8
lldb/source/Plugins/SymbolFile/DWARF/DWARFTypeUnit.h
View File

@ -18,6 +18,14 @@ public:
void Dump(lldb_private::Stream *s) const override;
uint64_t GetTypeHash() { return m_header.GetTypeHash(); }
dw_offset_t GetTypeOffset() { return GetOffset() + m_header.GetTypeOffset(); }
static bool classof(const DWARFUnit *unit) {
return unit->GetUnitType() == DW_UT_type;
}
private:
DWARFTypeUnit(SymbolFileDWARF *dwarf, lldb::user_id_t uid,
const DWARFUnitHeader &header,

10
lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
View File

@ -715,9 +715,16 @@ DWARFUnitHeader::extract(const DWARFDataExtractor &data, DIERef::Section section
section == DIERef::Section::DebugTypes ? DW_UT_type : DW_UT_compile;
}
if (header.IsTypeUnit()) {
header.m_type_hash = data.GetU64(offset_ptr);
header.m_type_offset = data.GetDWARFOffset(offset_ptr);
}
bool length_OK = data.ValidOffset(header.GetNextUnitOffset() - 1);
bool version_OK = SymbolFileDWARF::SupportedVersion(header.m_version);
bool addr_size_OK = (header.m_addr_size == 4) || (header.m_addr_size == 8);
bool type_offset_OK =
!header.IsTypeUnit() || (header.m_type_offset <= header.GetLength());
if (!length_OK)
return llvm::make_error<llvm::object::GenericBinaryError>(
@ -728,6 +735,9 @@ DWARFUnitHeader::extract(const DWARFDataExtractor &data, DIERef::Section section
if (!addr_size_OK)
return llvm::make_error<llvm::object::GenericBinaryError>(
"Invalid unit address size");
if (!type_offset_OK)
return llvm::make_error<llvm::object::GenericBinaryError>(
"Type offset out of range");
return header;
}

8
lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.h
View File

@ -41,6 +41,10 @@ class DWARFUnitHeader {
dw_offset_t m_abbr_offset = 0;
uint8_t m_unit_type = 0;
uint8_t m_addr_size = 0;
uint64_t m_type_hash = 0;
uint32_t m_type_offset = 0;
uint64_t m_dwo_id = 0;
DWARFUnitHeader() = default;
@ -52,6 +56,8 @@ public:
dw_offset_t GetLength() const { return m_length; }
dw_offset_t GetAbbrOffset() const { return m_abbr_offset; }
uint8_t GetUnitType() const { return m_unit_type; }
uint64_t GetTypeHash() const { return m_type_hash; }
dw_offset_t GetTypeOffset() const { return m_type_offset; }
bool IsTypeUnit() const {
return m_unit_type == DW_UT_type || m_unit_type == DW_UT_split_type;
}
@ -205,6 +211,8 @@ public:
DIERef::Section GetDebugSection() const { return m_section; }
uint8_t GetUnitType() const { return m_header.GetUnitType(); }
protected:
DWARFUnit(SymbolFileDWARF *dwarf, lldb::user_id_t uid,
const DWARFUnitHeader &header,