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clang-p2996/llvm/lib/DebugInfo/DWARF/DWARFDebugLoc.cpp
J. Ryan Stinnett f807c5e492 [DebugInfo] Add expression decoding for DW_OP_implicit_pointer (#102923) 
This allows `llvm-dwarfdump` to decode the DWARF 5 opcode
`DW_OP_implicit_pointer` (0xa0). GCC makes use of this opcode in recent
versions. LLVM contains some (unfinished) support as well. With existing
usage in the ecosystem, adding decoding support here seems reasonable.
2024-08-13 15:34:21 +01:00

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//===- DWARFDebugLoc.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 "llvm/DebugInfo/DWARF/DWARFDebugLoc.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/DebugInfo/DIContext.h"
#include "llvm/DebugInfo/DWARF/DWARFAddressRange.h"
#include "llvm/DebugInfo/DWARF/DWARFExpression.h"
#include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
#include "llvm/DebugInfo/DWARF/DWARFLocationExpression.h"
#include "llvm/DebugInfo/DWARF/DWARFUnit.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cinttypes>
#include <cstdint>
using namespace llvm;
using object::SectionedAddress;
namespace llvm {
class DWARFObject;
}
namespace {
class DWARFLocationInterpreter {
std::optional<object::SectionedAddress> Base;
std::function<std::optional<object::SectionedAddress>(uint32_t)> LookupAddr;
public:
DWARFLocationInterpreter(
std::optional<object::SectionedAddress> Base,
std::function<std::optional<object::SectionedAddress>(uint32_t)>
LookupAddr)
: Base(Base), LookupAddr(std::move(LookupAddr)) {}
Expected<std::optional<DWARFLocationExpression>>
Interpret(const DWARFLocationEntry &E);
};
} // namespace
static Error createResolverError(uint32_t Index, unsigned Kind) {
return make_error<ResolverError>(Index, (dwarf::LoclistEntries)Kind);
}
Expected<std::optional<DWARFLocationExpression>>
DWARFLocationInterpreter::Interpret(const DWARFLocationEntry &E) {
switch (E.Kind) {
case dwarf::DW_LLE_end_of_list:
return std::nullopt;
case dwarf::DW_LLE_base_addressx: {
Base = LookupAddr(E.Value0);
if (!Base)
return createResolverError(E.Value0, E.Kind);
return std::nullopt;
}
case dwarf::DW_LLE_startx_endx: {
std::optional<SectionedAddress> LowPC = LookupAddr(E.Value0);
if (!LowPC)
return createResolverError(E.Value0, E.Kind);
std::optional<SectionedAddress> HighPC = LookupAddr(E.Value1);
if (!HighPC)
return createResolverError(E.Value1, E.Kind);
return DWARFLocationExpression{
DWARFAddressRange{LowPC->Address, HighPC->Address, LowPC->SectionIndex},
E.Loc};
}
case dwarf::DW_LLE_startx_length: {
std::optional<SectionedAddress> LowPC = LookupAddr(E.Value0);
if (!LowPC)
return createResolverError(E.Value0, E.Kind);
return DWARFLocationExpression{DWARFAddressRange{LowPC->Address,
LowPC->Address + E.Value1,
LowPC->SectionIndex},
E.Loc};
}
case dwarf::DW_LLE_offset_pair: {
if (!Base) {
return createStringError(inconvertibleErrorCode(),
"Unable to resolve location list offset pair: "
"Base address not defined");
}
DWARFAddressRange Range{Base->Address + E.Value0, Base->Address + E.Value1,
Base->SectionIndex};
if (Range.SectionIndex == SectionedAddress::UndefSection)
Range.SectionIndex = E.SectionIndex;
return DWARFLocationExpression{Range, E.Loc};
}
case dwarf::DW_LLE_default_location:
return DWARFLocationExpression{std::nullopt, E.Loc};
case dwarf::DW_LLE_base_address:
Base = SectionedAddress{E.Value0, E.SectionIndex};
return std::nullopt;
case dwarf::DW_LLE_start_end:
return DWARFLocationExpression{
DWARFAddressRange{E.Value0, E.Value1, E.SectionIndex}, E.Loc};
case dwarf::DW_LLE_start_length:
return DWARFLocationExpression{
DWARFAddressRange{E.Value0, E.Value0 + E.Value1, E.SectionIndex},
E.Loc};
default:
llvm_unreachable("unreachable locations list kind");
}
}
static void dumpExpression(raw_ostream &OS, DIDumpOptions DumpOpts,
ArrayRef<uint8_t> Data, bool IsLittleEndian,
unsigned AddressSize, DWARFUnit *U) {
DWARFDataExtractor Extractor(Data, IsLittleEndian, AddressSize);
std::optional<dwarf::DwarfFormat> Format;
if (U)
Format = U->getFormat();
DWARFExpression(Extractor, AddressSize, Format).print(OS, DumpOpts, U);
}
bool DWARFLocationTable::dumpLocationList(
uint64_t *Offset, raw_ostream &OS, std::optional<SectionedAddress> BaseAddr,
const DWARFObject &Obj, DWARFUnit *U, DIDumpOptions DumpOpts,
unsigned Indent) const {
DWARFLocationInterpreter Interp(
BaseAddr, [U](uint32_t Index) -> std::optional<SectionedAddress> {
if (U)
return U->getAddrOffsetSectionItem(Index);
return std::nullopt;
});
OS << format("0x%8.8" PRIx64 ": ", *Offset);
Error E = visitLocationList(Offset, [&](const DWARFLocationEntry &E) {
Expected<std::optional<DWARFLocationExpression>> Loc = Interp.Interpret(E);
if (!Loc || DumpOpts.DisplayRawContents)
dumpRawEntry(E, OS, Indent, DumpOpts, Obj);
if (Loc && *Loc) {
OS << "\n";
OS.indent(Indent);
if (DumpOpts.DisplayRawContents)
OS << " => ";
DIDumpOptions RangeDumpOpts(DumpOpts);
RangeDumpOpts.DisplayRawContents = false;
if (Loc.get()->Range)
Loc.get()->Range->dump(OS, Data.getAddressSize(), RangeDumpOpts, &Obj);
else
OS << "<default>";
}
if (!Loc)
consumeError(Loc.takeError());
if (E.Kind != dwarf::DW_LLE_base_address &&
E.Kind != dwarf::DW_LLE_base_addressx &&
E.Kind != dwarf::DW_LLE_end_of_list) {
OS << ": ";
dumpExpression(OS, DumpOpts, E.Loc, Data.isLittleEndian(),
Data.getAddressSize(), U);
}
return true;
});
if (E) {
DumpOpts.RecoverableErrorHandler(std::move(E));
return false;
}
return true;
}
Error DWARFLocationTable::visitAbsoluteLocationList(
uint64_t Offset, std::optional<SectionedAddress> BaseAddr,
std::function<std::optional<SectionedAddress>(uint32_t)> LookupAddr,
function_ref<bool(Expected<DWARFLocationExpression>)> Callback) const {
DWARFLocationInterpreter Interp(BaseAddr, std::move(LookupAddr));
return visitLocationList(&Offset, [&](const DWARFLocationEntry &E) {
Expected<std::optional<DWARFLocationExpression>> Loc = Interp.Interpret(E);
if (!Loc)
return Callback(Loc.takeError());
if (*Loc)
return Callback(**Loc);
return true;
});
}
void DWARFDebugLoc::dump(raw_ostream &OS, const DWARFObject &Obj,
DIDumpOptions DumpOpts,
std::optional<uint64_t> DumpOffset) const {
auto BaseAddr = std::nullopt;
unsigned Indent = 12;
if (DumpOffset) {
dumpLocationList(&*DumpOffset, OS, BaseAddr, Obj, nullptr, DumpOpts,
Indent);
} else {
uint64_t Offset = 0;
StringRef Separator;
bool CanContinue = true;
while (CanContinue && Data.isValidOffset(Offset)) {
OS << Separator;
Separator = "\n";
CanContinue = dumpLocationList(&Offset, OS, BaseAddr, Obj, nullptr,
DumpOpts, Indent);
OS << '\n';
}
}
}
Error DWARFDebugLoc::visitLocationList(
uint64_t *Offset,
function_ref<bool(const DWARFLocationEntry &)> Callback) const {
DataExtractor::Cursor C(*Offset);
while (true) {
uint64_t SectionIndex;
uint64_t Value0 = Data.getRelocatedAddress(C);
uint64_t Value1 = Data.getRelocatedAddress(C, &SectionIndex);
DWARFLocationEntry E;
// The end of any given location list is marked by an end of list entry,
// which consists of a 0 for the beginning address offset and a 0 for the
// ending address offset. A beginning offset of 0xff...f marks the base
// address selection entry.
if (Value0 == 0 && Value1 == 0) {
E.Kind = dwarf::DW_LLE_end_of_list;
} else if (Value0 == (Data.getAddressSize() == 4 ? -1U : -1ULL)) {
E.Kind = dwarf::DW_LLE_base_address;
E.Value0 = Value1;
E.SectionIndex = SectionIndex;
} else {
E.Kind = dwarf::DW_LLE_offset_pair;
E.Value0 = Value0;
E.Value1 = Value1;
E.SectionIndex = SectionIndex;
unsigned Bytes = Data.getU16(C);
// A single location description describing the location of the object...
Data.getU8(C, E.Loc, Bytes);
}
if (!C)
return C.takeError();
if (!Callback(E) || E.Kind == dwarf::DW_LLE_end_of_list)
break;
}
*Offset = C.tell();
return Error::success();
}
void DWARFDebugLoc::dumpRawEntry(const DWARFLocationEntry &Entry,
raw_ostream &OS, unsigned Indent,
DIDumpOptions DumpOpts,
const DWARFObject &Obj) const {
uint64_t Value0, Value1;
switch (Entry.Kind) {
case dwarf::DW_LLE_base_address:
Value0 = Data.getAddressSize() == 4 ? -1U : -1ULL;
Value1 = Entry.Value0;
break;
case dwarf::DW_LLE_offset_pair:
Value0 = Entry.Value0;
Value1 = Entry.Value1;
break;
case dwarf::DW_LLE_end_of_list:
return;
default:
llvm_unreachable("Not possible in DWARF4!");
}
OS << '\n';
OS.indent(Indent);
OS << '(' << format_hex(Value0, 2 + Data.getAddressSize() * 2) << ", "
<< format_hex(Value1, 2 + Data.getAddressSize() * 2) << ')';
DWARFFormValue::dumpAddressSection(Obj, OS, DumpOpts, Entry.SectionIndex);
}
Error DWARFDebugLoclists::visitLocationList(
uint64_t *Offset, function_ref<bool(const DWARFLocationEntry &)> F) const {
DataExtractor::Cursor C(*Offset);
bool Continue = true;
while (Continue) {
DWARFLocationEntry E;
E.Kind = Data.getU8(C);
switch (E.Kind) {
case dwarf::DW_LLE_end_of_list:
break;
case dwarf::DW_LLE_base_addressx:
E.Value0 = Data.getULEB128(C);
break;
case dwarf::DW_LLE_startx_endx:
E.Value0 = Data.getULEB128(C);
E.Value1 = Data.getULEB128(C);
break;
case dwarf::DW_LLE_startx_length:
E.Value0 = Data.getULEB128(C);
// Pre-DWARF 5 has different interpretation of the length field. We have
// to support both pre- and standartized styles for the compatibility.
if (Version < 5)
E.Value1 = Data.getU32(C);
else
E.Value1 = Data.getULEB128(C);
break;
case dwarf::DW_LLE_offset_pair:
E.Value0 = Data.getULEB128(C);
E.Value1 = Data.getULEB128(C);
E.SectionIndex = SectionedAddress::UndefSection;
break;
case dwarf::DW_LLE_default_location:
break;
case dwarf::DW_LLE_base_address:
E.Value0 = Data.getRelocatedAddress(C, &E.SectionIndex);
break;
case dwarf::DW_LLE_start_end:
E.Value0 = Data.getRelocatedAddress(C, &E.SectionIndex);
E.Value1 = Data.getRelocatedAddress(C);
break;
case dwarf::DW_LLE_start_length:
E.Value0 = Data.getRelocatedAddress(C, &E.SectionIndex);
E.Value1 = Data.getULEB128(C);
break;
default:
cantFail(C.takeError());
return createStringError(errc::illegal_byte_sequence,
"LLE of kind %x not supported", (int)E.Kind);
}
if (E.Kind != dwarf::DW_LLE_base_address &&
E.Kind != dwarf::DW_LLE_base_addressx &&
E.Kind != dwarf::DW_LLE_end_of_list) {
unsigned Bytes = Version >= 5 ? Data.getULEB128(C) : Data.getU16(C);
// A single location description describing the location of the object...
Data.getU8(C, E.Loc, Bytes);
}
if (!C)
return C.takeError();
Continue = F(E) && E.Kind != dwarf::DW_LLE_end_of_list;
}
*Offset = C.tell();
return Error::success();
}
void DWARFDebugLoclists::dumpRawEntry(const DWARFLocationEntry &Entry,
raw_ostream &OS, unsigned Indent,
DIDumpOptions DumpOpts,
const DWARFObject &Obj) const {
size_t MaxEncodingStringLength = 0;
#define HANDLE_DW_LLE(ID, NAME) \
MaxEncodingStringLength = std::max(MaxEncodingStringLength, \
dwarf::LocListEncodingString(ID).size());
#include "llvm/BinaryFormat/Dwarf.def"
OS << "\n";
OS.indent(Indent);
StringRef EncodingString = dwarf::LocListEncodingString(Entry.Kind);
// Unsupported encodings should have been reported during parsing.
assert(!EncodingString.empty() && "Unknown loclist entry encoding");
OS << format("%-*s(", MaxEncodingStringLength, EncodingString.data());
unsigned FieldSize = 2 + 2 * Data.getAddressSize();
switch (Entry.Kind) {
case dwarf::DW_LLE_end_of_list:
case dwarf::DW_LLE_default_location:
break;
case dwarf::DW_LLE_startx_endx:
case dwarf::DW_LLE_startx_length:
case dwarf::DW_LLE_offset_pair:
case dwarf::DW_LLE_start_end:
case dwarf::DW_LLE_start_length:
OS << format_hex(Entry.Value0, FieldSize) << ", "
<< format_hex(Entry.Value1, FieldSize);
break;
case dwarf::DW_LLE_base_addressx:
case dwarf::DW_LLE_base_address:
OS << format_hex(Entry.Value0, FieldSize);
break;
}
OS << ')';
switch (Entry.Kind) {
case dwarf::DW_LLE_base_address:
case dwarf::DW_LLE_start_end:
case dwarf::DW_LLE_start_length:
DWARFFormValue::dumpAddressSection(Obj, OS, DumpOpts, Entry.SectionIndex);
break;
default:
break;
}
}
void DWARFDebugLoclists::dumpRange(uint64_t StartOffset, uint64_t Size,
raw_ostream &OS, const DWARFObject &Obj,
DIDumpOptions DumpOpts) {
if (!Data.isValidOffsetForDataOfSize(StartOffset, Size)) {
OS << "Invalid dump range\n";
return;
}
uint64_t Offset = StartOffset;
StringRef Separator;
bool CanContinue = true;
while (CanContinue && Offset < StartOffset + Size) {
OS << Separator;
Separator = "\n";
CanContinue = dumpLocationList(&Offset, OS, /*BaseAddr=*/std::nullopt, Obj,
nullptr, DumpOpts, /*Indent=*/12);
OS << '\n';
}
}
void llvm::ResolverError::log(raw_ostream &OS) const {
OS << format("unable to resolve indirect address %u for: %s", Index,
dwarf::LocListEncodingString(Kind).data());
}
char llvm::ResolverError::ID;
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