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llvm/llvm-project/6b26457a0ef2994de54606eb5c356cb897cadda2/./lldb/source/Expression/DWARFExpression.cpp
blob: f884724766714b3b40abc446c07289b14aa3cbff [file]
//===-- DWARFExpression.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
//
//===----------------------------------------------------------------------===//
//
// The DWARF expression opcodes evaluated in this file are defined by the DWARF
// Debugging Information Format specification, available at:
//
// https://dwarfstd.org/
//
//===----------------------------------------------------------------------===//
#include "lldb/Expression/DWARFExpression.h"
#include <cinttypes>
#include <limits>
#include <optional>
#include <vector>
#include "lldb/Core/Module.h"
#include "lldb/Core/Value.h"
#include "lldb/Utility/DataEncoder.h"
#include "lldb/Utility/LLDBLog.h"
#include "lldb/Utility/Log.h"
#include "lldb/Utility/RegisterValue.h"
#include "lldb/Utility/Scalar.h"
#include "lldb/Utility/StreamString.h"
#include "lldb/Host/Host.h"
#include "lldb/Utility/Endian.h"
#include "lldb/Symbol/Function.h"
#include "lldb/Target/ABI.h"
#include "lldb/Target/ExecutionContext.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Target/StackFrame.h"
#include "lldb/Target/StackID.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/Thread.h"
#include "llvm/DebugInfo/DWARF/DWARFExpressionPrinter.h"
#include "llvm/DebugInfo/DWARF/LowLevel/DWARFExpression.h"
#include "llvm/Support/ErrorExtras.h"
using namespace lldb;
using namespace lldb_private;
using namespace lldb_private::plugin::dwarf;
using namespace llvm::dwarf;
namespace {
/// The location description kinds described by the DWARF v5
/// specification. Composite locations are handled out-of-band and
/// thus aren't part of the enum.
enum LocationDescriptionKind {
Empty,
Memory,
Register,
Implicit
/* Composite*/
};
/// Aggregates the inputs, derived pointers, and mutable evaluation state for
/// a single DWARF expression evaluation. Passed by reference to every helper
/// so they don't need to re-thread these individually.
struct EvalContext {
ExecutionContext *exe_ctx;
RegisterContext *reg_ctx;
lldb::ModuleSP module_sp;
const DWARFExpression::Delegate *dwarf_cu;
lldb::RegisterKind reg_kind;
const Value *initial_value_ptr;
const Value *object_address_ptr;
Process *process = nullptr;
Target *target = nullptr;
StackFrame *frame = nullptr;
/// Mutable evaluation state.
/// @{
std::vector<Value> stack;
Value pieces;
uint64_t op_piece_offset = 0;
LocationDescriptionKind loc_desc_kind = Memory;
/// @}
EvalContext(ExecutionContext *exe_ctx, RegisterContext *reg_ctx,
lldb::ModuleSP module_sp,
const DWARFExpression::Delegate *dwarf_cu,
lldb::RegisterKind reg_kind, const Value *initial_value_ptr,
const Value *object_address_ptr)
: exe_ctx(exe_ctx), reg_ctx(reg_ctx), module_sp(std::move(module_sp)),
dwarf_cu(dwarf_cu), reg_kind(reg_kind),
initial_value_ptr(initial_value_ptr),
object_address_ptr(object_address_ptr) {
if (exe_ctx) {
process = exe_ctx->GetProcessPtr();
frame = exe_ctx->GetFramePtr();
target = exe_ctx->GetTargetPtr();
}
if (this->reg_ctx == nullptr && frame)
this->reg_ctx = frame->GetRegisterContext().get();
}
};
} // namespace
// DWARFExpression constructor
DWARFExpression::DWARFExpression() : m_data() {}
DWARFExpression::DWARFExpression(const DataExtractor &data) : m_data(data) {}
// Destructor
DWARFExpression::~DWARFExpression() = default;
bool DWARFExpression::IsValid() const { return m_data.GetByteSize() > 0; }
void DWARFExpression::UpdateValue(uint64_t const_value,
lldb::offset_t const_value_byte_size,
uint8_t addr_byte_size) {
if (!const_value_byte_size)
return;
m_data.SetData(
DataBufferSP(new DataBufferHeap(&const_value, const_value_byte_size)));
m_data.SetByteOrder(endian::InlHostByteOrder());
m_data.SetAddressByteSize(addr_byte_size);
}
void DWARFExpression::DumpLocation(Stream *s, lldb::DescriptionLevel level,
ABI *abi,
llvm::DIDumpOptions options) const {
auto *MCRegInfo = abi ? &abi->GetMCRegisterInfo() : nullptr;
auto GetRegName = [&MCRegInfo](uint64_t DwarfRegNum,
bool IsEH) -> llvm::StringRef {
if (!MCRegInfo)
return {};
if (std::optional<unsigned> LLVMRegNum =
MCRegInfo->getLLVMRegNum(DwarfRegNum, IsEH))
if (const char *RegName = MCRegInfo->getName(*LLVMRegNum))
return llvm::StringRef(RegName);
return {};
};
options.GetNameForDWARFReg = GetRegName;
llvm::DWARFExpression E(m_data.GetAsLLVM(), m_data.GetAddressByteSize());
llvm::printDwarfExpression(&E, s->AsRawOstream(), options, nullptr);
}
RegisterKind DWARFExpression::GetRegisterKind() const { return m_reg_kind; }
void DWARFExpression::SetRegisterKind(RegisterKind reg_kind) {
m_reg_kind = reg_kind;
}
llvm::Error
DWARFExpression::ReadRegisterValueAsScalar(RegisterContext *reg_ctx,
lldb::RegisterKind reg_kind,
uint32_t reg_num, Value &value) {
if (reg_ctx == nullptr)
return llvm::createStringError("no register context in frame");
const uint32_t native_reg =
reg_ctx->ConvertRegisterKindToRegisterNumber(reg_kind, reg_num);
if (native_reg == LLDB_INVALID_REGNUM)
return llvm::createStringError(
"unable to convert register kind=%u reg_num=%u to a native "
"register number",
reg_kind, reg_num);
const RegisterInfo *reg_info = reg_ctx->GetRegisterInfoAtIndex(native_reg);
RegisterValue reg_value;
if (reg_ctx->ReadRegister(reg_info, reg_value)) {
if (reg_value.GetScalarValue(value.GetScalar())) {
value.SetValueType(Value::ValueType::Scalar);
value.SetContext(Value::ContextType::RegisterInfo,
const_cast<RegisterInfo *>(reg_info));
return llvm::Error::success();
}
// If we get this error, then we need to implement a value buffer in
// the dwarf expression evaluation function...
return llvm::createStringError(
"register %s can't be converted to a scalar value", reg_info->name);
}
return llvm::createStringError("register %s is not available",
reg_info->name);
}
/// Return the length in bytes of the set of operands for \p op. No guarantees
/// are made on the state of \p data after this call.
static lldb::offset_t
GetOpcodeDataSize(const DataExtractor &data, const lldb::offset_t data_offset,
const LocationAtom op,
const DWARFExpression::Delegate *dwarf_cu) {
lldb::offset_t offset = data_offset;
switch (op) {
// Only used in LLVM metadata.
case DW_OP_LLVM_fragment:
case DW_OP_LLVM_convert:
case DW_OP_LLVM_tag_offset:
case DW_OP_LLVM_entry_value:
case DW_OP_LLVM_implicit_pointer:
case DW_OP_LLVM_arg:
case DW_OP_LLVM_extract_bits_sext:
case DW_OP_LLVM_extract_bits_zext:
break;
// Vendor extensions:
case DW_OP_HP_is_value:
case DW_OP_HP_fltconst4:
case DW_OP_HP_fltconst8:
case DW_OP_HP_mod_range:
case DW_OP_HP_unmod_range:
case DW_OP_HP_tls:
case DW_OP_INTEL_bit_piece:
case DW_OP_WASM_location:
case DW_OP_WASM_location_int:
case DW_OP_APPLE_uninit:
case DW_OP_PGI_omp_thread_num:
case DW_OP_hi_user:
case DW_OP_GNU_implicit_pointer:
break;
case DW_OP_addr:
case DW_OP_call_ref: // 0x9a 1 address sized offset of DIE (DWARF3)
return data.GetAddressByteSize();
// Opcodes with no arguments
case DW_OP_deref: // 0x06
case DW_OP_dup: // 0x12
case DW_OP_drop: // 0x13
case DW_OP_over: // 0x14
case DW_OP_swap: // 0x16
case DW_OP_rot: // 0x17
case DW_OP_xderef: // 0x18
case DW_OP_abs: // 0x19
case DW_OP_and: // 0x1a
case DW_OP_div: // 0x1b
case DW_OP_minus: // 0x1c
case DW_OP_mod: // 0x1d
case DW_OP_mul: // 0x1e
case DW_OP_neg: // 0x1f
case DW_OP_not: // 0x20
case DW_OP_or: // 0x21
case DW_OP_plus: // 0x22
case DW_OP_shl: // 0x24
case DW_OP_shr: // 0x25
case DW_OP_shra: // 0x26
case DW_OP_xor: // 0x27
case DW_OP_eq: // 0x29
case DW_OP_ge: // 0x2a
case DW_OP_gt: // 0x2b
case DW_OP_le: // 0x2c
case DW_OP_lt: // 0x2d
case DW_OP_ne: // 0x2e
case DW_OP_lit0: // 0x30
case DW_OP_lit1: // 0x31
case DW_OP_lit2: // 0x32
case DW_OP_lit3: // 0x33
case DW_OP_lit4: // 0x34
case DW_OP_lit5: // 0x35
case DW_OP_lit6: // 0x36
case DW_OP_lit7: // 0x37
case DW_OP_lit8: // 0x38
case DW_OP_lit9: // 0x39
case DW_OP_lit10: // 0x3A
case DW_OP_lit11: // 0x3B
case DW_OP_lit12: // 0x3C
case DW_OP_lit13: // 0x3D
case DW_OP_lit14: // 0x3E
case DW_OP_lit15: // 0x3F
case DW_OP_lit16: // 0x40
case DW_OP_lit17: // 0x41
case DW_OP_lit18: // 0x42
case DW_OP_lit19: // 0x43
case DW_OP_lit20: // 0x44
case DW_OP_lit21: // 0x45
case DW_OP_lit22: // 0x46
case DW_OP_lit23: // 0x47
case DW_OP_lit24: // 0x48
case DW_OP_lit25: // 0x49
case DW_OP_lit26: // 0x4A
case DW_OP_lit27: // 0x4B
case DW_OP_lit28: // 0x4C
case DW_OP_lit29: // 0x4D
case DW_OP_lit30: // 0x4E
case DW_OP_lit31: // 0x4f
case DW_OP_reg0: // 0x50
case DW_OP_reg1: // 0x51
case DW_OP_reg2: // 0x52
case DW_OP_reg3: // 0x53
case DW_OP_reg4: // 0x54
case DW_OP_reg5: // 0x55
case DW_OP_reg6: // 0x56
case DW_OP_reg7: // 0x57
case DW_OP_reg8: // 0x58
case DW_OP_reg9: // 0x59
case DW_OP_reg10: // 0x5A
case DW_OP_reg11: // 0x5B
case DW_OP_reg12: // 0x5C
case DW_OP_reg13: // 0x5D
case DW_OP_reg14: // 0x5E
case DW_OP_reg15: // 0x5F
case DW_OP_reg16: // 0x60
case DW_OP_reg17: // 0x61
case DW_OP_reg18: // 0x62
case DW_OP_reg19: // 0x63
case DW_OP_reg20: // 0x64
case DW_OP_reg21: // 0x65
case DW_OP_reg22: // 0x66
case DW_OP_reg23: // 0x67
case DW_OP_reg24: // 0x68
case DW_OP_reg25: // 0x69
case DW_OP_reg26: // 0x6A
case DW_OP_reg27: // 0x6B
case DW_OP_reg28: // 0x6C
case DW_OP_reg29: // 0x6D
case DW_OP_reg30: // 0x6E
case DW_OP_reg31: // 0x6F
case DW_OP_nop: // 0x96
case DW_OP_push_object_address: // 0x97 DWARF3
case DW_OP_form_tls_address: // 0x9b DWARF3
case DW_OP_call_frame_cfa: // 0x9c DWARF3
case DW_OP_stack_value: // 0x9f DWARF4
case DW_OP_GNU_push_tls_address: // 0xe0 GNU extension
return 0;
// Opcodes with a single 1 byte arguments
case DW_OP_const1u: // 0x08 1 1-byte constant
case DW_OP_const1s: // 0x09 1 1-byte constant
case DW_OP_pick: // 0x15 1 1-byte stack index
case DW_OP_deref_size: // 0x94 1 1-byte size of data retrieved
case DW_OP_xderef_size: // 0x95 1 1-byte size of data retrieved
case DW_OP_deref_type: // 0xa6 1 1-byte constant
return 1;
// Opcodes with a single 2 byte arguments
case DW_OP_const2u: // 0x0a 1 2-byte constant
case DW_OP_const2s: // 0x0b 1 2-byte constant
case DW_OP_skip: // 0x2f 1 signed 2-byte constant
case DW_OP_bra: // 0x28 1 signed 2-byte constant
case DW_OP_call2: // 0x98 1 2-byte offset of DIE (DWARF3)
return 2;
// Opcodes with a single 4 byte arguments
case DW_OP_const4u: // 0x0c 1 4-byte constant
case DW_OP_const4s: // 0x0d 1 4-byte constant
case DW_OP_call4: // 0x99 1 4-byte offset of DIE (DWARF3)
return 4;
// Opcodes with a single 8 byte arguments
case DW_OP_const8u: // 0x0e 1 8-byte constant
case DW_OP_const8s: // 0x0f 1 8-byte constant
return 8;
// All opcodes that have a single ULEB (signed or unsigned) argument
case DW_OP_constu: // 0x10 1 ULEB128 constant
case DW_OP_consts: // 0x11 1 SLEB128 constant
case DW_OP_plus_uconst: // 0x23 1 ULEB128 addend
case DW_OP_breg0: // 0x70 1 ULEB128 register
case DW_OP_breg1: // 0x71 1 ULEB128 register
case DW_OP_breg2: // 0x72 1 ULEB128 register
case DW_OP_breg3: // 0x73 1 ULEB128 register
case DW_OP_breg4: // 0x74 1 ULEB128 register
case DW_OP_breg5: // 0x75 1 ULEB128 register
case DW_OP_breg6: // 0x76 1 ULEB128 register
case DW_OP_breg7: // 0x77 1 ULEB128 register
case DW_OP_breg8: // 0x78 1 ULEB128 register
case DW_OP_breg9: // 0x79 1 ULEB128 register
case DW_OP_breg10: // 0x7a 1 ULEB128 register
case DW_OP_breg11: // 0x7b 1 ULEB128 register
case DW_OP_breg12: // 0x7c 1 ULEB128 register
case DW_OP_breg13: // 0x7d 1 ULEB128 register
case DW_OP_breg14: // 0x7e 1 ULEB128 register
case DW_OP_breg15: // 0x7f 1 ULEB128 register
case DW_OP_breg16: // 0x80 1 ULEB128 register
case DW_OP_breg17: // 0x81 1 ULEB128 register
case DW_OP_breg18: // 0x82 1 ULEB128 register
case DW_OP_breg19: // 0x83 1 ULEB128 register
case DW_OP_breg20: // 0x84 1 ULEB128 register
case DW_OP_breg21: // 0x85 1 ULEB128 register
case DW_OP_breg22: // 0x86 1 ULEB128 register
case DW_OP_breg23: // 0x87 1 ULEB128 register
case DW_OP_breg24: // 0x88 1 ULEB128 register
case DW_OP_breg25: // 0x89 1 ULEB128 register
case DW_OP_breg26: // 0x8a 1 ULEB128 register
case DW_OP_breg27: // 0x8b 1 ULEB128 register
case DW_OP_breg28: // 0x8c 1 ULEB128 register
case DW_OP_breg29: // 0x8d 1 ULEB128 register
case DW_OP_breg30: // 0x8e 1 ULEB128 register
case DW_OP_breg31: // 0x8f 1 ULEB128 register
case DW_OP_regx: // 0x90 1 ULEB128 register
case DW_OP_fbreg: // 0x91 1 SLEB128 offset
case DW_OP_piece: // 0x93 1 ULEB128 size of piece addressed
case DW_OP_convert: // 0xa8 1 ULEB128 offset
case DW_OP_reinterpret: // 0xa9 1 ULEB128 offset
case DW_OP_addrx: // 0xa1 1 ULEB128 index
case DW_OP_constx: // 0xa2 1 ULEB128 index
case DW_OP_xderef_type: // 0xa7 1 ULEB128 index
case DW_OP_GNU_addr_index: // 0xfb 1 ULEB128 index
case DW_OP_GNU_const_index: // 0xfc 1 ULEB128 index
data.Skip_LEB128(&offset);
return offset - data_offset;
// All opcodes that have a 2 ULEB (signed or unsigned) arguments
case DW_OP_bregx: // 0x92 2 ULEB128 register followed by SLEB128 offset
case DW_OP_bit_piece: // 0x9d ULEB128 bit size, ULEB128 bit offset (DWARF3);
case DW_OP_regval_type: // 0xa5 ULEB128 + ULEB128
data.Skip_LEB128(&offset);
data.Skip_LEB128(&offset);
return offset - data_offset;
case DW_OP_implicit_value: // 0x9e ULEB128 size followed by block of that size
// (DWARF4)
{
uint64_t block_len = data.GetULEB128(&offset);
offset += block_len;
return offset - data_offset;
}
case DW_OP_implicit_pointer: // 0xa0 4-byte (or 8-byte for DWARF 64) constant
// + LEB128
{
data.Skip_LEB128(&offset);
return (dwarf_cu ? dwarf_cu->GetAddressByteSize() : 4) + offset -
data_offset;
}
case DW_OP_GNU_entry_value:
case DW_OP_entry_value: // 0xa3 ULEB128 size + variable-length block
{
uint64_t subexpr_len = data.GetULEB128(&offset);
return (offset - data_offset) + subexpr_len;
}
case DW_OP_const_type: // 0xa4 ULEB128 + size + variable-length block
{
data.Skip_LEB128(&offset);
uint8_t length = data.GetU8(&offset);
return (offset - data_offset) + length;
}
case DW_OP_LLVM_user: // 0xe9: ULEB128 + variable length constant
{
uint64_t constants = data.GetULEB128(&offset);
return (offset - data_offset) + constants;
}
}
if (dwarf_cu)
return dwarf_cu->GetVendorDWARFOpcodeSize(data, data_offset, op);
return LLDB_INVALID_OFFSET;
}
static const char *DW_OP_value_to_name(uint32_t val) {
static char invalid[100];
llvm::StringRef llvmstr = llvm::dwarf::OperationEncodingString(val);
if (llvmstr.empty()) {
snprintf(invalid, sizeof(invalid), "Unknown DW_OP constant: 0x%x", val);
return invalid;
}
return llvmstr.data();
}
llvm::Expected<lldb::addr_t> DWARFExpression::GetLocation_DW_OP_addr(
const DWARFExpression::Delegate *dwarf_cu) const {
lldb::offset_t offset = 0;
while (m_data.ValidOffset(offset)) {
const LocationAtom op = static_cast<LocationAtom>(m_data.GetU8(&offset));
if (op == DW_OP_addr)
return m_data.GetAddress(&offset);
if (op == DW_OP_GNU_addr_index || op == DW_OP_addrx) {
const uint64_t index = m_data.GetULEB128(&offset);
if (dwarf_cu)
return dwarf_cu->ReadAddressFromDebugAddrSection(index);
return llvm::createStringError("cannot evaluate %s without a DWARF unit",
DW_OP_value_to_name(op));
}
const lldb::offset_t op_arg_size =
GetOpcodeDataSize(m_data, offset, op, dwarf_cu);
if (op_arg_size == LLDB_INVALID_OFFSET)
return llvm::createStringError("cannot get opcode data size for %s",
DW_OP_value_to_name(op));
offset += op_arg_size;
}
return LLDB_INVALID_ADDRESS;
}
bool DWARFExpression::Update_DW_OP_addr(
const DWARFExpression::Delegate *dwarf_cu, lldb::addr_t file_addr) {
lldb::offset_t offset = 0;
while (m_data.ValidOffset(offset)) {
const LocationAtom op = static_cast<LocationAtom>(m_data.GetU8(&offset));
if (op == DW_OP_addr) {
const uint32_t addr_byte_size = m_data.GetAddressByteSize();
// We have to make a copy of the data as we don't know if this data is
// from a read only memory mapped buffer, so we duplicate all of the data
// first, then modify it, and if all goes well, we then replace the data
// for this expression
// Make en encoder that contains a copy of the location expression data
// so we can write the address into the buffer using the correct byte
// order.
DataEncoder encoder(m_data.GetDataStart(), m_data.GetByteSize(),
m_data.GetByteOrder(), addr_byte_size);
// Replace the address in the new buffer
if (encoder.PutAddress(offset, file_addr) == UINT32_MAX)
return false;
// All went well, so now we can reset the data using a shared pointer to
// the heap data so "m_data" will now correctly manage the heap data.
m_data.SetData(encoder.GetDataBuffer());
return true;
}
if (op == DW_OP_addrx) {
// Replace DW_OP_addrx with DW_OP_addr, since we can't modify the
// read-only debug_addr table.
// Subtract one to account for the opcode.
llvm::ArrayRef data_before_op = m_data.GetData().take_front(offset - 1);
// Read the addrx index to determine how many bytes it needs.
const lldb::offset_t old_offset = offset;
m_data.GetULEB128(&offset);
if (old_offset == offset)
return false;
llvm::ArrayRef data_after_op = m_data.GetData().drop_front(offset);
DataEncoder encoder(m_data.GetByteOrder(), m_data.GetAddressByteSize());
encoder.AppendData(data_before_op);
encoder.AppendU8(DW_OP_addr);
encoder.AppendAddress(file_addr);
encoder.AppendData(data_after_op);
m_data.SetData(encoder.GetDataBuffer());
return true;
}
const lldb::offset_t op_arg_size =
GetOpcodeDataSize(m_data, offset, op, dwarf_cu);
if (op_arg_size == LLDB_INVALID_OFFSET)
break;
offset += op_arg_size;
}
return false;
}
bool DWARFExpression::ContainsThreadLocalStorage(
const DWARFExpression::Delegate *dwarf_cu) const {
lldb::offset_t offset = 0;
while (m_data.ValidOffset(offset)) {
const LocationAtom op = static_cast<LocationAtom>(m_data.GetU8(&offset));
if (op == DW_OP_form_tls_address || op == DW_OP_GNU_push_tls_address)
return true;
const lldb::offset_t op_arg_size =
GetOpcodeDataSize(m_data, offset, op, dwarf_cu);
if (op_arg_size == LLDB_INVALID_OFFSET)
return false;
offset += op_arg_size;
}
return false;
}
bool DWARFExpression::IsImplicit(
const DWARFExpression::Delegate *dwarf_cu) const {
lldb::offset_t offset = 0;
while (m_data.ValidOffset(offset)) {
const LocationAtom op = static_cast<LocationAtom>(m_data.GetU8(&offset));
switch (op) {
// Implicit locations have no storage in the inferior. Composite locations
// might, but we conservatively treat them as non-writable because LLDB
// does not write their pieces back.
case DW_OP_stack_value:
case DW_OP_implicit_value:
case DW_OP_implicit_pointer:
case DW_OP_piece:
case DW_OP_bit_piece:
return true;
default:
break;
}
const lldb::offset_t op_arg_size =
GetOpcodeDataSize(m_data, offset, op, dwarf_cu);
if (op_arg_size == LLDB_INVALID_OFFSET)
return false;
offset += op_arg_size;
}
return false;
}
bool DWARFExpression::LinkThreadLocalStorage(
const DWARFExpression::Delegate *dwarf_cu,
std::function<lldb::addr_t(lldb::addr_t file_addr)> const
&link_address_callback) {
const uint32_t addr_byte_size = m_data.GetAddressByteSize();
// We have to make a copy of the data as we don't know if this data is from a
// read only memory mapped buffer, so we duplicate all of the data first,
// then modify it, and if all goes well, we then replace the data for this
// expression.
// Make en encoder that contains a copy of the location expression data so we
// can write the address into the buffer using the correct byte order.
DataEncoder encoder(m_data.GetDataStart(), m_data.GetByteSize(),
m_data.GetByteOrder(), addr_byte_size);
lldb::offset_t offset = 0;
lldb::offset_t const_offset = 0;
lldb::addr_t const_value = 0;
size_t const_byte_size = 0;
while (m_data.ValidOffset(offset)) {
const LocationAtom op = static_cast<LocationAtom>(m_data.GetU8(&offset));
bool decoded_data = false;
switch (op) {
case DW_OP_const4u:
// Remember the const offset in case we later have a
// DW_OP_form_tls_address or DW_OP_GNU_push_tls_address
const_offset = offset;
const_value = m_data.GetU32(&offset);
decoded_data = true;
const_byte_size = 4;
break;
case DW_OP_const8u:
// Remember the const offset in case we later have a
// DW_OP_form_tls_address or DW_OP_GNU_push_tls_address
const_offset = offset;
const_value = m_data.GetU64(&offset);
decoded_data = true;
const_byte_size = 8;
break;
case DW_OP_form_tls_address:
case DW_OP_GNU_push_tls_address:
// DW_OP_form_tls_address and DW_OP_GNU_push_tls_address must be preceded
// by a file address on the stack. We assume that DW_OP_const4u or
// DW_OP_const8u is used for these values, and we check that the last
// opcode we got before either of these was DW_OP_const4u or
// DW_OP_const8u. If so, then we can link the value accordingly. For
// Darwin, the value in the DW_OP_const4u or DW_OP_const8u is the file
// address of a structure that contains a function pointer, the pthread
// key and the offset into the data pointed to by the pthread key. So we
// must link this address and also set the module of this expression to
// the new_module_sp so we can resolve the file address correctly
if (const_byte_size > 0) {
lldb::addr_t linked_file_addr = link_address_callback(const_value);
if (linked_file_addr == LLDB_INVALID_ADDRESS)
return false;
// Replace the address in the new buffer
if (encoder.PutUnsigned(const_offset, const_byte_size,
linked_file_addr) == UINT32_MAX)
return false;
}
break;
default:
const_offset = 0;
const_value = 0;
const_byte_size = 0;
break;
}
if (!decoded_data) {
const lldb::offset_t op_arg_size =
GetOpcodeDataSize(m_data, offset, op, dwarf_cu);
if (op_arg_size == LLDB_INVALID_OFFSET)
return false;
else
offset += op_arg_size;
}
}
m_data.SetData(encoder.GetDataBuffer());
return true;
}
static llvm::Error Evaluate_DW_OP_entry_value(EvalContext &eval_ctx,
llvm::ArrayRef<uint8_t> subexpr) {
Log *log = GetLog(LLDBLog::Expressions);
// DW_OP_entry_value(sub-expr) describes the location a variable had upon
// function entry: this variable location is presumed to be optimized out at
// the current PC value. The caller of the function may have call site
// information that describes an alternate location for the variable (e.g. a
// constant literal, or a spilled stack value) in the parent frame.
//
// Example (this is pseudo-code & pseudo-DWARF, but hopefully illustrative):
//
// void child(int &sink, int x) {
// ...
// /* "x" gets optimized out. */
//
// /* The location of "x" here is: DW_OP_entry_value($reg2). */
// ++sink;
// }
//
// void parent() {
// int sink;
//
// /*
// * The callsite information emitted here is:
// *
// * DW_TAG_call_site
// * DW_AT_return_pc ... (for "child(sink, 123);")
// * DW_TAG_call_site_parameter (for "sink")
// * DW_AT_location ($reg1)
// * DW_AT_call_value ($SP - 8)
// * DW_TAG_call_site_parameter (for "x")
// * DW_AT_location ($reg2)
// * DW_AT_call_value ($literal 123)
// *
// * DW_TAG_call_site
// * DW_AT_return_pc ... (for "child(sink, 456);")
// * ...
// */
// child(sink, 123);
// child(sink, 456);
// }
//
// When the program stops at "++sink" within `child`, the debugger determines
// the call site by analyzing the return address. Once the call site is found,
// the debugger determines which parameter is referenced by DW_OP_entry_value
// and evaluates the corresponding location for that parameter in `parent`.
// 1. Find the function which pushed the current frame onto the stack.
if ((!eval_ctx.exe_ctx || !eval_ctx.exe_ctx->HasTargetScope()) ||
!eval_ctx.reg_ctx) {
return llvm::createStringError("no exe/reg context");
}
StackFrame *current_frame = eval_ctx.exe_ctx->GetFramePtr();
Thread *thread = eval_ctx.exe_ctx->GetThreadPtr();
if (!current_frame || !thread)
return llvm::createStringError("no current frame/thread");
Target &target = eval_ctx.exe_ctx->GetTargetRef();
StackFrameSP parent_frame = nullptr;
addr_t return_pc = LLDB_INVALID_ADDRESS;
uint32_t current_frame_idx = current_frame->GetFrameIndex();
for (uint32_t parent_frame_idx = current_frame_idx + 1;; parent_frame_idx++) {
parent_frame = thread->GetStackFrameAtIndex(parent_frame_idx);
// If this is null, we're at the end of the stack.
if (!parent_frame)
break;
// Record the first valid return address, even if this is an inlined frame,
// in order to look up the associated call edge in the first non-inlined
// parent frame.
if (return_pc == LLDB_INVALID_ADDRESS) {
return_pc = parent_frame->GetFrameCodeAddress().GetLoadAddress(&target);
LLDB_LOG(log, "immediate ancestor with pc = {0:x}", return_pc);
}
// If we've found an inlined frame, skip it (these have no call site
// parameters).
if (parent_frame->IsInlined())
continue;
// We've found the first non-inlined parent frame.
break;
}
if (!parent_frame || !parent_frame->GetRegisterContext()) {
return llvm::createStringError("no parent frame with reg ctx");
}
Function *parent_func =
parent_frame->GetSymbolContext(eSymbolContextFunction).function;
if (!parent_func)
return llvm::createStringError("no parent function");
// 2. Find the call edge in the parent function responsible for creating the
// current activation.
Function *current_func =
current_frame->GetSymbolContext(eSymbolContextFunction).function;
if (!current_func)
return llvm::createStringError("no current function");
CallEdge *call_edge = nullptr;
ModuleList &modlist = target.GetImages();
ExecutionContext parent_exe_ctx = *eval_ctx.exe_ctx;
parent_exe_ctx.SetFrameSP(parent_frame);
if (!parent_frame->IsArtificial()) {
// If the parent frame is not artificial, the current activation may be
// produced by an ambiguous tail call. In this case, refuse to proceed.
call_edge = parent_func->GetCallEdgeForReturnAddress(return_pc, target);
if (!call_edge) {
return llvm::createStringErrorV(
"no call edge for retn-pc = {0:x} in parent frame {1}", return_pc,
parent_func->GetName());
}
SymbolContext callee = call_edge->GetCallee(modlist, parent_exe_ctx);
if (callee.function != current_func) {
return llvm::createStringError(
"ambiguous call sequence, can't find real parent frame");
}
} else {
// The StackFrameList solver machinery has deduced that an unambiguous tail
// call sequence that produced the current activation. The first edge in
// the parent that points to the current function must be valid.
for (auto &edge : parent_func->GetTailCallingEdges()) {
if (edge->GetCallee(modlist, parent_exe_ctx).function == current_func) {
call_edge = edge.get();
break;
}
}
}
if (!call_edge)
return llvm::createStringError("no unambiguous edge from parent "
"to current function");
// 3. Attempt to locate the DW_OP_entry_value expression in the set of
// available call site parameters. If found, evaluate the corresponding
// parameter in the context of the parent frame.
const CallSiteParameter *matched_param = nullptr;
for (const CallSiteParameter &param : call_edge->GetCallSiteParameters()) {
DataExtractor param_subexpr_extractor;
if (!param.LocationInCallee.GetExpressionData(param_subexpr_extractor))
continue;
lldb::offset_t param_subexpr_offset = 0;
const void *param_subexpr_data =
param_subexpr_extractor.GetData(&param_subexpr_offset, subexpr.size());
if (!param_subexpr_data ||
param_subexpr_extractor.BytesLeft(param_subexpr_offset) != 0)
continue;
// At this point, the DW_OP_entry_value sub-expression and the callee-side
// expression in the call site parameter are known to have the same length.
// Check whether they are equal.
//
// Note that an equality check is sufficient: the contents of the
// DW_OP_entry_value subexpression are only used to identify the right call
// site parameter in the parent, and do not require any special handling.
if (memcmp(subexpr.data(), param_subexpr_data, subexpr.size()) == 0) {
matched_param = &param;
break;
}
}
if (!matched_param)
return llvm::createStringError("no matching call site param found");
// TODO: Add support for DW_OP_push_object_address within a DW_OP_entry_value
// subexpresion whenever llvm does.
const DWARFExpressionList &param_expr = matched_param->LocationInCaller;
// Recurse through the public entry point so the call-site parameter is
// evaluated with a fresh EvalContext (separate stack and piece state).
llvm::Expected<Value> maybe_result = param_expr.Evaluate(
&parent_exe_ctx, parent_frame->GetRegisterContext().get(),
LLDB_INVALID_ADDRESS,
/*initial_value_ptr=*/nullptr,
/*object_address_ptr=*/nullptr);
if (!maybe_result) {
LLDB_LOG(log,
"Evaluate_DW_OP_entry_value: call site param evaluation failed");
return maybe_result.takeError();
}
eval_ctx.stack.push_back(*maybe_result);
return llvm::Error::success();
}
/// Adjust value's ValueType according to the kind of location description.
static void UpdateValueTypeFromLocationDescription(EvalContext &eval_ctx,
LocationDescriptionKind kind,
Value *value = nullptr) {
// Note that this function is conflating DWARF expressions with
// DWARF location descriptions. Perhaps it would be better to define
// a wrapper for DWARFExpression::Eval() that deals with DWARF
// location descriptions (which consist of one or more DWARF
// expressions). But doing this would mean we'd also need factor the
// handling of DW_OP_(bit_)piece out of this function.
if (eval_ctx.dwarf_cu && eval_ctx.dwarf_cu->GetVersion() >= 4) {
Log *log = GetLog(LLDBLog::Expressions);
const char *log_msg = "DWARF location description kind: %s";
switch (kind) {
case Empty:
LLDB_LOGF(log, log_msg, "Empty");
break;
case Memory:
LLDB_LOGF(log, log_msg, "Memory");
if (value->GetValueType() == Value::ValueType::Scalar)
value->SetValueType(Value::ValueType::LoadAddress);
break;
case Register:
LLDB_LOGF(log, log_msg, "Register");
value->SetValueType(Value::ValueType::Scalar);
break;
case Implicit:
LLDB_LOGF(log, log_msg, "Implicit");
if (value->GetValueType() == Value::ValueType::LoadAddress)
value->SetValueType(Value::ValueType::Scalar);
break;
}
}
}
/// Helper function to move common code used to resolve a file address and turn
/// into a load address.
///
/// \param eval_ctx Evaluation context (provides exe_ctx and module_sp).
/// \param dw_op_type C-style string used to vary the error output
/// \param file_addr the file address we are trying to resolve and turn into a
/// load address
/// \param so_addr out parameter, will be set to load address or section offset
/// \param check_sectionoffset bool which determines if having a section offset
/// but not a load address is considerd a success
/// \returns std::optional containing the load address if resolving and getting
/// the load address succeed or an empty Optinal otherwise. If
/// check_sectionoffset is true we consider LLDB_INVALID_ADDRESS a
/// success if so_addr.IsSectionOffset() is true.
static llvm::Expected<lldb::addr_t>
ResolveLoadAddress(EvalContext &eval_ctx, const char *dw_op_type,
lldb::addr_t file_addr, Address &so_addr,
bool check_sectionoffset = false) {
if (!eval_ctx.module_sp)
return llvm::createStringError("need module to resolve file address for %s",
dw_op_type);
if (!eval_ctx.module_sp->ResolveFileAddress(file_addr, so_addr))
return llvm::createStringError("failed to resolve file address in module");
const addr_t load_addr = so_addr.GetLoadAddress(eval_ctx.target);
if (load_addr == LLDB_INVALID_ADDRESS &&
(check_sectionoffset && !so_addr.IsSectionOffset()))
return llvm::createStringError("failed to resolve load address");
return load_addr;
}
/// @brief Helper function to load sized data from a uint8_t buffer.
///
/// @param addr_bytes The buffer containing raw data.
/// @param size_addr_bytes How large is the underlying raw data.
/// @param byte_order What is the byte order of the underlying data.
/// @param size How much of the underlying data we want to use.
/// @return The underlying data converted into a Scalar.
static Scalar DerefSizeExtractDataHelper(uint8_t *addr_bytes,
size_t size_addr_bytes,
ByteOrder byte_order, size_t size) {
DataExtractor addr_data(addr_bytes, size_addr_bytes, byte_order, size);
lldb::offset_t addr_data_offset = 0;
if (size <= 8)
return addr_data.GetMaxU64(&addr_data_offset, size);
return addr_data.GetAddress(&addr_data_offset);
}
static llvm::Error Evaluate_DW_OP_deref(EvalContext &eval_ctx,
LocationAtom opcode, unsigned size,
size_t size_addr_bytes) {
const char *op_name = DW_OP_value_to_name(opcode);
if (eval_ctx.stack.empty())
return llvm::createStringError("expression stack empty for %s", op_name);
if (size == 0 || size > 8)
return llvm::createStringError("Invalid address size for %s: %u", op_name,
size);
if (opcode == DW_OP_deref_size && size > size_addr_bytes)
return llvm::createStringError(
"DW_OP_deref_size size (%u) exceeds address size (%zu)", size,
size_addr_bytes);
// Deref a register or implicit location and truncate the value to `size`
// bytes. See the corresponding comment in DW_OP_deref for more details on
// why we deref these locations this way.
if (eval_ctx.loc_desc_kind == Register ||
eval_ctx.loc_desc_kind == Implicit) {
// Reset context to default values.
eval_ctx.loc_desc_kind = Memory;
eval_ctx.stack.back().ClearContext();
// Truncate the value on top of the stack to *size* bytes then
// extend to the size of an address (e.g. generic type).
Scalar scalar = eval_ctx.stack.back().GetScalar();
scalar.TruncOrExtendTo(size * 8, /*sign=*/false);
scalar.TruncOrExtendTo(size_addr_bytes * 8,
/*sign=*/false);
eval_ctx.stack.back().GetScalar() = scalar;
return llvm::Error::success();
}
Value::ValueType value_type = eval_ctx.stack.back().GetValueType();
switch (value_type) {
case Value::ValueType::HostAddress: {
void *src = (void *)eval_ctx.stack.back().GetScalar().ULongLong();
intptr_t ptr;
::memcpy(&ptr, src, sizeof(void *));
// I can't decide whether the size operand should apply to the bytes in
// their lldb-host endianness or the target endianness.. I doubt this'll
// ever come up but I'll opt for assuming big endian regardless.
switch (size) {
case 1:
ptr = ptr & 0xff;
break;
case 2:
ptr = ptr & 0xffff;
break;
case 3:
ptr = ptr & 0xffffff;
break;
case 4:
ptr = ptr & 0xffffffff;
break;
// The casts are added to work around the case where intptr_t is a 32-bit
// quantity. Presumably we won't hit the 5..7 cases if (void*) is 32-bits in
// this program.
case 5:
ptr = (intptr_t)ptr & 0xffffffffffULL;
break;
case 6:
ptr = (intptr_t)ptr & 0xffffffffffffULL;
break;
case 7:
ptr = (intptr_t)ptr & 0xffffffffffffffULL;
break;
default:
break;
}
eval_ctx.stack.back().GetScalar() = ptr;
eval_ctx.stack.back().ClearContext();
} break;
case Value::ValueType::FileAddress: {
auto file_addr =
eval_ctx.stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
Address so_addr;
auto maybe_load_addr =
ResolveLoadAddress(eval_ctx, op_name, file_addr, so_addr,
/*check_sectionoffset=*/true);
if (!maybe_load_addr)
return maybe_load_addr.takeError();
addr_t load_addr = *maybe_load_addr;
if (load_addr == LLDB_INVALID_ADDRESS && so_addr.IsSectionOffset()) {
uint8_t addr_bytes[8];
Status error;
if (!eval_ctx.target ||
eval_ctx.target->ReadMemory(so_addr, &addr_bytes, size, error,
/*force_live_memory=*/false) != size)
return llvm::createStringError("failed to dereference pointer for %s: "
"%s\n",
op_name, error.AsCString());
ObjectFile *objfile = eval_ctx.module_sp->GetObjectFile();
eval_ctx.stack.back().GetScalar() = DerefSizeExtractDataHelper(
addr_bytes, size, objfile->GetByteOrder(), size);
eval_ctx.stack.back().ClearContext();
break;
}
eval_ctx.stack.back().GetScalar() = load_addr;
// Fall through to load address promotion code below.
}
[[fallthrough]];
case Value::ValueType::Scalar:
// Promote Scalar to LoadAddress and fall through.
eval_ctx.stack.back().SetValueType(Value::ValueType::LoadAddress);
[[fallthrough]];
case Value::ValueType::LoadAddress: {
if (!eval_ctx.exe_ctx)
return llvm::createStringError("no execution context for %s", op_name);
if (!eval_ctx.process)
return llvm::createStringError("no process for %s", op_name);
lldb::addr_t pointer_addr =
eval_ctx.stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
uint8_t addr_bytes[sizeof(lldb::addr_t)];
Status error;
if (eval_ctx.process->ReadMemory(pointer_addr, &addr_bytes, size, error) !=
size)
return llvm::createStringError(
"failed to dereference pointer from 0x%" PRIx64 " for %s: %s\n",
pointer_addr, op_name, error.AsCString());
eval_ctx.stack.back().GetScalar() = DerefSizeExtractDataHelper(
addr_bytes, sizeof(addr_bytes), eval_ctx.process->GetByteOrder(), size);
eval_ctx.stack.back().ClearContext();
} break;
case Value::ValueType::Invalid:
return llvm::createStringError("invalid value for %s", op_name);
}
// Both operations push a generic, address-sized result. The truncation to
// `size` bytes is unnecessary here because the branches above already limit
// the value to `size` bytes; it is only done for consistency with the
// Register/Implicit path above.
eval_ctx.stack.back().GetScalar().TruncOrExtendTo(size * 8, /*sign=*/false);
eval_ctx.stack.back().GetScalar().TruncOrExtendTo(size_addr_bytes * 8,
/*sign=*/false);
return llvm::Error::success();
}
static llvm::Error Evaluate_DW_OP_piece(EvalContext &eval_ctx,
uint64_t piece_byte_size) {
LocationDescriptionKind piece_locdesc = eval_ctx.loc_desc_kind;
// Reset for the next piece.
eval_ctx.loc_desc_kind = Memory;
if (piece_byte_size == 0)
return llvm::Error::success();
Value curr_piece;
if (eval_ctx.stack.empty()) {
UpdateValueTypeFromLocationDescription(eval_ctx,
LocationDescriptionKind::Empty);
// In a multi-piece expression, this means that the current piece is
// not available. Fill with zeros for now by resizing the data and
// appending it
curr_piece.ResizeData(piece_byte_size);
// Note that "0" is not a correct value for the unknown bits.
// It would be better to also return a mask of valid bits together
// with the expression result, so the debugger can print missing
// members as "<optimized out>" or something.
::memset(curr_piece.GetBuffer().GetBytes(), 0, piece_byte_size);
eval_ctx.pieces.AppendDataToHostBuffer(curr_piece);
} else {
Status error;
// Extract the current piece into "curr_piece"
Value curr_piece_source_value(eval_ctx.stack.back());
eval_ctx.stack.pop_back();
UpdateValueTypeFromLocationDescription(eval_ctx, piece_locdesc,
&curr_piece_source_value);
const Value::ValueType curr_piece_source_value_type =
curr_piece_source_value.GetValueType();
Scalar &scalar = curr_piece_source_value.GetScalar();
lldb::addr_t addr = scalar.ULongLong(LLDB_INVALID_ADDRESS);
switch (curr_piece_source_value_type) {
case Value::ValueType::Invalid:
return llvm::createStringError("invalid value type");
case Value::ValueType::FileAddress:
if (eval_ctx.target) {
curr_piece_source_value.ConvertToLoadAddress(eval_ctx.module_sp.get(),
eval_ctx.target);
addr = scalar.ULongLong(LLDB_INVALID_ADDRESS);
} else {
return llvm::createStringError(
"unable to convert file address 0x%" PRIx64 " to load address "
"for DW_OP_piece(%" PRIu64 "): "
"no target available",
addr, piece_byte_size);
}
[[fallthrough]];
case Value::ValueType::LoadAddress: {
if (eval_ctx.target) {
if (curr_piece.ResizeData(piece_byte_size) == piece_byte_size) {
if (eval_ctx.target->ReadMemory(
Address(addr), curr_piece.GetBuffer().GetBytes(),
piece_byte_size, error,
/*force_live_memory=*/false) != piece_byte_size) {
const char *addr_type =
(curr_piece_source_value_type == Value::ValueType::LoadAddress)
? "load"
: "file";
return llvm::createStringError(
"failed to read memory DW_OP_piece(%" PRIu64
") from %s address 0x%" PRIx64,
piece_byte_size, addr_type, addr);
}
} else {
return llvm::createStringError(
"failed to resize the piece memory buffer for "
"DW_OP_piece(%" PRIu64 ")",
piece_byte_size);
}
}
} break;
case Value::ValueType::HostAddress: {
// DW_OP_implicit_value uses a host-address Value to own its bytes. For
// a full-width piece, the address is only an implementation detail and
// the backing bytes are the value of the piece.
if (piece_locdesc == Implicit &&
curr_piece_source_value.GetBuffer().GetByteSize() ==
piece_byte_size) {
curr_piece = curr_piece_source_value;
break;
}
return llvm::createStringError(
"failed to read memory DW_OP_piece(%" PRIu64
") from host address 0x%" PRIx64,
piece_byte_size, addr);
} break;
case Value::ValueType::Scalar: {
uint32_t bit_size = piece_byte_size * 8;
uint32_t bit_offset = 0;
if (!scalar.ExtractBitfield(bit_size, bit_offset)) {
return llvm::createStringError(
"unable to extract %" PRIu64 " bytes from a %" PRIu64
" byte scalar value.",
piece_byte_size,
(uint64_t)curr_piece_source_value.GetScalar().GetByteSize());
}
// We have seen a case where we have expression like:
// DW_OP_lit0, DW_OP_stack_value, DW_OP_piece 0x28
// here we are assuming the compiler was trying to zero
// extend the value that we should append to the buffer.
scalar.TruncOrExtendTo(bit_size, /*sign=*/false);
curr_piece.GetScalar() = scalar;
} break;
}
// Check if this is the first piece?
if (eval_ctx.op_piece_offset == 0) {
// This is the first piece, we should push it back onto the stack
// so subsequent pieces will be able to access this piece and add
// to it.
if (eval_ctx.pieces.AppendDataToHostBuffer(curr_piece) == 0) {
return llvm::createStringError("failed to append piece data");
}
} else {
// If this is the second or later piece there should be a value on
// the stack.
if (eval_ctx.pieces.GetBuffer().GetByteSize() !=
eval_ctx.op_piece_offset) {
return llvm::createStringError(
"DW_OP_piece for offset %" PRIu64
" but top of stack is of size %" PRIu64,
eval_ctx.op_piece_offset,
eval_ctx.pieces.GetBuffer().GetByteSize());
}
if (eval_ctx.pieces.AppendDataToHostBuffer(curr_piece) == 0)
return llvm::createStringError("failed to append piece data");
}
}
eval_ctx.op_piece_offset += piece_byte_size;
return llvm::Error::success();
}
static llvm::Error Evaluate_DW_OP_convert(EvalContext &eval_ctx,
uint64_t relative_die_offset) {
uint64_t bit_size;
llvm::dwarf::TypeKind encoding;
if (relative_die_offset == 0) {
// The generic type has the size of an address on the target
// machine and an unspecified signedness. Scalar has no
// "unspecified signedness", so we use unsigned types.
if (!eval_ctx.module_sp)
return llvm::createStringError("no module");
encoding = llvm::dwarf::DW_ATE_unsigned;
bit_size = eval_ctx.module_sp->GetArchitecture().GetAddressByteSize() * 8;
if (!bit_size)
return llvm::createStringError("unspecified architecture");
} else {
if (!eval_ctx.dwarf_cu)
return llvm::createStringError(
"DW_OP_convert with a DIE offset requires a DWARF unit");
auto bit_size_encoding_or_err =
eval_ctx.dwarf_cu->GetDIEBitSizeAndEncoding(relative_die_offset);
if (!bit_size_encoding_or_err)
return bit_size_encoding_or_err.takeError();
bit_size = bit_size_encoding_or_err->first;
encoding = bit_size_encoding_or_err->second;
}
Scalar &scalar = eval_ctx.stack.back().GetScalar();
if (encoding == llvm::dwarf::DW_ATE_float) {
const llvm::fltSemantics *semantics;
switch (bit_size) {
case 32:
semantics = &llvm::APFloat::IEEEsingle();
break;
case 64:
semantics = &llvm::APFloat::IEEEdouble();
break;
case 80:
semantics = &llvm::APFloat::x87DoubleExtended();
break;
default:
return llvm::createStringError("unsupported floating-point type size");
}
if (scalar.GetType() == Scalar::e_float) {
llvm::APFloat value = scalar.GetAPFloat();
bool loses_info;
value.convert(*semantics, llvm::APFloat::rmNearestTiesToEven,
&loses_info);
scalar = Scalar(std::move(value));
} else if (!scalar.FloatPromote(*semantics)) {
return llvm::createStringError("cannot convert value to floating point");
}
return llvm::Error::success();
}
const bool sign = encoding == llvm::dwarf::DW_ATE_signed ||
encoding == llvm::dwarf::DW_ATE_signed_char;
if (scalar.GetType() == Scalar::e_float) {
if (bit_size > std::numeric_limits<uint16_t>::max())
return llvm::createStringError("unsupported integer type size: %" PRIu64,
bit_size);
llvm::APSInt value(static_cast<unsigned>(bit_size),
/*isUnsigned=*/!sign);
bool is_exact;
llvm::APFloat::opStatus status = scalar.GetAPFloat().convertToInteger(
value, llvm::APFloat::rmTowardZero, &is_exact);
if (status & llvm::APFloat::opInvalidOp)
return llvm::createStringError(
"cannot convert floating-point value to integer");
scalar = Scalar(std::move(value));
} else {
scalar.TruncOrExtendTo(bit_size, sign);
}
return llvm::Error::success();
}
static llvm::Error Evaluate_DW_OP_form_tls_address(EvalContext &eval_ctx,
LocationAtom opcode) {
if (eval_ctx.stack.empty())
return llvm::createStringError("%s needs an argument",
opcode == DW_OP_form_tls_address
? "DW_OP_form_tls_address"
: "DW_OP_GNU_push_tls_address");
if (!eval_ctx.exe_ctx || !eval_ctx.module_sp)
return llvm::createStringError("no context to evaluate TLS within");
Thread *thread = eval_ctx.exe_ctx->GetThreadPtr();
if (!thread)
return llvm::createStringError("no thread to evaluate TLS within");
// Lookup the TLS block address for this thread and module.
const addr_t tls_file_addr =
eval_ctx.stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
const addr_t tls_load_addr =
thread->GetThreadLocalData(eval_ctx.module_sp, tls_file_addr);
if (tls_load_addr == LLDB_INVALID_ADDRESS)
return llvm::createStringError(
"no TLS data currently exists for this thread");
eval_ctx.stack.back().GetScalar() = tls_load_addr;
eval_ctx.stack.back().SetValueType(Value::ValueType::LoadAddress);
return llvm::Error::success();
}
static llvm::Error Evaluate_DW_OP_fbreg(EvalContext &eval_ctx,
int64_t fbreg_offset) {
if (!eval_ctx.exe_ctx)
return llvm::createStringError("NULL execution context for DW_OP_fbreg");
if (!eval_ctx.frame)
return llvm::createStringError(
"invalid stack frame in context for DW_OP_fbreg opcode");
Scalar value;
if (llvm::Error err = eval_ctx.frame->GetFrameBaseValue(value))
return err;
value += fbreg_offset;
eval_ctx.stack.push_back(value);
eval_ctx.stack.back().SetValueType(Value::ValueType::LoadAddress);
return llvm::Error::success();
}
static llvm::Error Evaluate_DW_OP_call_frame_cfa(EvalContext &eval_ctx) {
if (!eval_ctx.frame)
return llvm::createStringError(
"invalid stack frame in context for DW_OP_call_frame_cfa opcode");
// Note that we don't have to parse FDEs because this DWARF expression
// is commonly evaluated with a valid stack frame.
StackID id = eval_ctx.frame->GetStackID();
addr_t cfa = id.GetCallFrameAddressWithMetadata();
if (cfa == LLDB_INVALID_ADDRESS)
return llvm::createStringError("stack frame does not include a canonical "
"frame address for DW_OP_call_frame_cfa "
"opcode");
eval_ctx.stack.push_back(Scalar(cfa));
eval_ctx.stack.back().SetValueType(Value::ValueType::LoadAddress);
return llvm::Error::success();
}
static llvm::Error CheckScalarOperandsHaveSameType(const Scalar &lhs,
const Scalar &rhs,
LocationAtom opcode,
size_t address_size) {
auto mismatch = [&](const char *what) {
return llvm::createStringError("%s requires operands to have the same %s",
DW_OP_value_to_name(opcode), what);
};
// Scalar does not preserve the original DWARF DIE, but it does carry the
// pieces of base-type information used by the evaluator: kind, size, and
// integer signedness.
if (lhs.GetType() != rhs.GetType())
return mismatch("type");
// Only integer scalars have signedness. Non-integer operands (e.g. floats)
// have no further scalar type information to compare once kind and size
// match.
if (lhs.GetType() != Scalar::e_int) {
if (lhs.GetByteSize() != rhs.GetByteSize())
return mismatch("size");
return llvm::Error::success();
}
// DWARF generic values are address-sized integers with unspecified
// signedness. LLDB does not explicitly preserve genericness on the
// expression stack, so treat integers at least as wide as the generic type
// as potentially generic and compatible with one another, regardless of
// exact width or signedness. This keeps common expressions working: e.g.
// DW_OP_breg produces a register-sized value while DW_OP_const* produces an
// address-sized one, yet both are meant to be generic. DW_OP_constu and
// DW_OP_consts also do not always use to_generic due to
// https://github.com/llvm/llvm-project/issues/47431. A precise fix would
// require tracking genericness directly, which is a larger type-system
// change.
if (address_size != 0 && lhs.GetByteSize() >= address_size &&
rhs.GetByteSize() >= address_size)
return llvm::Error::success();
// For non-generic integer operands, size and signedness are part of the
// base-type information preserved by Scalar, so require them to match.
if (lhs.GetByteSize() != rhs.GetByteSize())
return mismatch("size");
if (lhs.IsSigned() != rhs.IsSigned())
return mismatch("signedness");
return llvm::Error::success();
}
// Scalar does not preserve DWARF's generic type identifier. Since generic
// values are address-sized integers, use the scalar kind and width as an
// approximation.
static bool IsPotentiallyGenericIntegerOperand(const Scalar &operand,
size_t address_size) {
return address_size != 0 && operand.GetType() == Scalar::e_int &&
operand.GetByteSize() == address_size;
}
llvm::Expected<Value> DWARFExpression::Evaluate(
ExecutionContext *exe_ctx, RegisterContext *reg_ctx,
lldb::ModuleSP module_sp, const DataExtractor &opcodes,
const DWARFExpression::Delegate *dwarf_cu,
const lldb::RegisterKind reg_kind, const Value *initial_value_ptr,
const Value *object_address_ptr) {
uint32_t address_size = opcodes.GetAddressByteSize();
llvm::DataExtractor expr_data = opcodes.GetAsLLVM();
llvm::DWARFExpression expr(expr_data, address_size);
if (expr_data.size() == 0)
return llvm::createStringError(
"no location, value may have been optimized out");
EvalContext eval_ctx(exe_ctx, reg_ctx, std::move(module_sp), dwarf_cu,
reg_kind, initial_value_ptr, object_address_ptr);
Stack &stack = eval_ctx.stack;
if (initial_value_ptr)
stack.push_back(*initial_value_ptr);
Value tmp;
uint32_t reg_num;
Log *log = GetLog(LLDBLog::Expressions);
// A generic type is "an integral type that has the size of an address and an
// unspecified signedness". For now, just use the signedness of the operand.
// TODO: Implement a real typed stack, and store the genericness of the value
// there.
auto to_generic = [&](auto v) {
// TODO: Avoid implicit trunc?
// See https://github.com/llvm/llvm-project/issues/112510.
bool is_signed = std::is_signed<decltype(v)>::value;
return Scalar(llvm::APSInt(
llvm::APInt(8 * address_size, v, is_signed, /*implicitTrunc=*/true),
!is_signed));
};
llvm::DWARFExpression::iterator op = expr.begin(), op_end = expr.end();
while (op != op_end) {
const uint64_t op_offset = op.getOffset();
const LocationAtom opcode = static_cast<LocationAtom>(op->getCode());
if (log && log->GetVerbose()) {
size_t count = stack.size();
LLDB_LOGF(log, "Stack before operation has %" PRIu64 " values:",
static_cast<uint64_t>(count));
for (size_t i = 0; i < count; ++i) {
StreamString new_value;
new_value.Printf("[%" PRIu64 "]", static_cast<uint64_t>(i));
stack[i].Dump(&new_value);
LLDB_LOGF(log, " %s", new_value.GetData());
}
LLDB_LOGF(log, "0x%8.8" PRIx64 ": %s", op_offset,
DW_OP_value_to_name(opcode));
}
if (std::optional<unsigned> arity = OperationArity(opcode)) {
if (stack.size() < *arity)
return llvm::createStringError(
"%s needs at least %d stack entries (stack has %d entries)",
DW_OP_value_to_name(opcode), *arity, stack.size());
}
switch (opcode) {
case DW_OP_addr:
stack.push_back(to_generic(op->getRawOperand(0)));
stack.back().SetValueType(Value::ValueType::FileAddress);
break;
case DW_OP_deref: {
size_t size = address_size;
if (llvm::Error err = Evaluate_DW_OP_deref(eval_ctx, opcode, size, size))
return err;
} break;
case DW_OP_deref_size: {
size_t size = op->getRawOperand(0);
if (llvm::Error err =
Evaluate_DW_OP_deref(eval_ctx, opcode, size, address_size))
return err;
} break;
case DW_OP_const1u:
stack.push_back(to_generic(op->getRawOperand(0)));
break;
case DW_OP_const1s:
stack.push_back(to_generic(static_cast<int8_t>(op->getRawOperand(0))));
break;
case DW_OP_const2u:
stack.push_back(to_generic(op->getRawOperand(0)));
break;
case DW_OP_const2s:
stack.push_back(to_generic(static_cast<int16_t>(op->getRawOperand(0))));
break;
case DW_OP_const4u:
stack.push_back(to_generic(op->getRawOperand(0)));
break;
case DW_OP_const4s:
stack.push_back(to_generic(static_cast<int32_t>(op->getRawOperand(0))));
break;
case DW_OP_const8u:
stack.push_back(to_generic(op->getRawOperand(0)));
break;
case DW_OP_const8s:
stack.push_back(to_generic(static_cast<int64_t>(op->getRawOperand(0))));
break;
case DW_OP_constu:
stack.push_back(to_generic(op->getRawOperand(0)));
break;
case DW_OP_consts:
stack.push_back(to_generic(static_cast<int64_t>(op->getRawOperand(0))));
break;
case DW_OP_dup:
if (stack.empty()) {
return llvm::createStringError("expression stack empty for DW_OP_dup");
} else
stack.push_back(stack.back());
break;
case DW_OP_drop:
if (stack.empty()) {
return llvm::createStringError("expression stack empty for DW_OP_drop");
} else
stack.pop_back();
break;
case DW_OP_over:
stack.push_back(stack[stack.size() - 2]);
break;
case DW_OP_pick: {
uint8_t pick_idx = op->getRawOperand(0);
if (pick_idx < stack.size())
stack.push_back(stack[stack.size() - 1 - pick_idx]);
else {
return llvm::createStringError(
"Index %u out of range for DW_OP_pick.\n", pick_idx);
}
} break;
case DW_OP_swap:
tmp = stack.back();
stack.back() = stack[stack.size() - 2];
stack[stack.size() - 2] = tmp;
break;
case DW_OP_rot: {
size_t last_idx = stack.size() - 1;
Value old_top = stack[last_idx];
stack[last_idx] = stack[last_idx - 1];
stack[last_idx - 1] = stack[last_idx - 2];
stack[last_idx - 2] = old_top;
} break;
case DW_OP_abs:
if (!stack.back().GetScalar().AbsoluteValue()) {
return llvm::createStringError(
"failed to take the absolute value of the first stack item");
}
break;
case DW_OP_and:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() = stack.back().GetScalar() & tmp.GetScalar();
break;
case DW_OP_div: {
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
opcode, address_size))
return err;
tmp = stack.back();
if (tmp.GetScalar().IsZero())
return llvm::createStringError("divide by zero");
stack.pop_back();
Scalar divisor, dividend;
divisor = tmp.GetScalar();
dividend = stack.back().GetScalar();
divisor.MakeSigned();
dividend.MakeSigned();
stack.back() = dividend / divisor;
if (!stack.back().GetScalar().IsValid())
return llvm::createStringError("divide failed");
} break;
case DW_OP_minus:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() = stack.back().GetScalar() - tmp.GetScalar();
break;
case DW_OP_mod:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
if (IsPotentiallyGenericIntegerOperand(tmp.GetScalar(), address_size) &&
IsPotentiallyGenericIntegerOperand(stack.back().GetScalar(),
address_size)) {
tmp.GetScalar().MakeUnsigned();
stack.back().GetScalar().MakeUnsigned();
}
stack.back().GetScalar() = stack.back().GetScalar() % tmp.GetScalar();
break;
case DW_OP_mul:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() = stack.back().GetScalar() * tmp.GetScalar();
break;
case DW_OP_neg:
if (!stack.back().GetScalar().UnaryNegate())
return llvm::createStringError("unary negate failed");
break;
case DW_OP_not:
if (!stack.back().GetScalar().OnesComplement())
return llvm::createStringError("logical NOT failed");
break;
case DW_OP_or:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() = stack.back().GetScalar() | tmp.GetScalar();
break;
case DW_OP_plus:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() += tmp.GetScalar();
break;
case DW_OP_plus_uconst: {
const uint64_t uconst_value = op->getRawOperand(0);
Scalar &operand = stack.back().GetScalar();
Scalar addend(uconst_value);
// The addend is interpreted as the same type as the popped operand
// (DWARF v5, 2.5.1.4). Give it the operand's exact integer type so
// the addition keeps the operand's width and wraparound semantics
// instead of promoting to a 64-bit unsigned value.
if (operand.GetType() == Scalar::e_int)
addend.TruncOrExtendTo(operand.GetAPSInt().getBitWidth(),
operand.GetAPSInt().isSigned());
operand += addend;
if (!operand.IsValid())
return llvm::createStringError("DW_OP_plus_uconst failed");
} break;
case DW_OP_shl:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() <<= tmp.GetScalar();
break;
case DW_OP_shr:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
if (!stack.back().GetScalar().ShiftRightLogical(tmp.GetScalar()))
return llvm::createStringError("DW_OP_shr failed");
break;
case DW_OP_shra:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() >>= tmp.GetScalar();
break;
case DW_OP_xor:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() = stack.back().GetScalar() ^ tmp.GetScalar();
break;
case DW_OP_skip: {
int16_t skip_offset = static_cast<int16_t>(op->getRawOperand(0));
lldb::offset_t new_offset = op->getEndOffset() + skip_offset;
// New offset can point at the end of the data, in this case we should
// terminate the DWARF expression evaluation (will happen in the loop
// condition).
if (new_offset <= expr_data.size()) {
op = op.skipBytes(skip_offset);
continue;
}
return llvm::createStringErrorV(
"Invalid opcode offset in DW_OP_skip: {0}+({1}) > {2}",
op->getEndOffset(), skip_offset, expr_data.size());
}
case DW_OP_bra: {
tmp = stack.back();
stack.pop_back();
int16_t bra_offset = static_cast<int16_t>(op->getRawOperand(0));
Scalar zero(0);
if (tmp.GetScalar() != zero) {
lldb::offset_t new_offset = op->getEndOffset() + bra_offset;
// New offset can point at the end of the data, in this case we should
// terminate the DWARF expression evaluation (will happen in the loop
// condition).
if (new_offset <= expr_data.size()) {
op = op.skipBytes(bra_offset);
continue;
}
return llvm::createStringErrorV(
"Invalid opcode offset in DW_OP_bra: {0}+({1}) > {2}",
op->getEndOffset(), bra_offset, expr_data.size());
}
} break;
case DW_OP_eq:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() =
to_generic(stack.back().GetScalar() == tmp.GetScalar());
break;
case DW_OP_ge:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
if (IsPotentiallyGenericIntegerOperand(tmp.GetScalar(), address_size) &&
IsPotentiallyGenericIntegerOperand(stack.back().GetScalar(),
address_size)) {
tmp.GetScalar().MakeSigned();
stack.back().GetScalar().MakeSigned();
}
stack.back().GetScalar() =
to_generic(stack.back().GetScalar() >= tmp.GetScalar());
break;
case DW_OP_gt:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
if (IsPotentiallyGenericIntegerOperand(tmp.GetScalar(), address_size) &&
IsPotentiallyGenericIntegerOperand(stack.back().GetScalar(),
address_size)) {
tmp.GetScalar().MakeSigned();
stack.back().GetScalar().MakeSigned();
}
stack.back().GetScalar() =
to_generic(stack.back().GetScalar() > tmp.GetScalar());
break;
case DW_OP_le:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
if (IsPotentiallyGenericIntegerOperand(tmp.GetScalar(), address_size) &&
IsPotentiallyGenericIntegerOperand(stack.back().GetScalar(),
address_size)) {
tmp.GetScalar().MakeSigned();
stack.back().GetScalar().MakeSigned();
}
stack.back().GetScalar() =
to_generic(stack.back().GetScalar() <= tmp.GetScalar());
break;
case DW_OP_lt:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
if (IsPotentiallyGenericIntegerOperand(tmp.GetScalar(), address_size) &&
IsPotentiallyGenericIntegerOperand(stack.back().GetScalar(),
address_size)) {
tmp.GetScalar().MakeSigned();
stack.back().GetScalar().MakeSigned();
}
stack.back().GetScalar() =
to_generic(stack.back().GetScalar() < tmp.GetScalar());
break;
case DW_OP_ne:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() =
to_generic(stack.back().GetScalar() != tmp.GetScalar());
break;
case DW_OP_lit0:
case DW_OP_lit1:
case DW_OP_lit2:
case DW_OP_lit3:
case DW_OP_lit4:
case DW_OP_lit5:
case DW_OP_lit6:
case DW_OP_lit7:
case DW_OP_lit8:
case DW_OP_lit9:
case DW_OP_lit10:
case DW_OP_lit11:
case DW_OP_lit12:
case DW_OP_lit13:
case DW_OP_lit14:
case DW_OP_lit15:
case DW_OP_lit16:
case DW_OP_lit17:
case DW_OP_lit18:
case DW_OP_lit19:
case DW_OP_lit20:
case DW_OP_lit21:
case DW_OP_lit22:
case DW_OP_lit23:
case DW_OP_lit24:
case DW_OP_lit25:
case DW_OP_lit26:
case DW_OP_lit27:
case DW_OP_lit28:
case DW_OP_lit29:
case DW_OP_lit30:
case DW_OP_lit31:
stack.push_back(to_generic(opcode - DW_OP_lit0));
break;
case DW_OP_reg0:
case DW_OP_reg1:
case DW_OP_reg2:
case DW_OP_reg3:
case DW_OP_reg4:
case DW_OP_reg5:
case DW_OP_reg6:
case DW_OP_reg7:
case DW_OP_reg8:
case DW_OP_reg9:
case DW_OP_reg10:
case DW_OP_reg11:
case DW_OP_reg12:
case DW_OP_reg13:
case DW_OP_reg14:
case DW_OP_reg15:
case DW_OP_reg16:
case DW_OP_reg17:
case DW_OP_reg18:
case DW_OP_reg19:
case DW_OP_reg20:
case DW_OP_reg21:
case DW_OP_reg22:
case DW_OP_reg23:
case DW_OP_reg24:
case DW_OP_reg25:
case DW_OP_reg26:
case DW_OP_reg27:
case DW_OP_reg28:
case DW_OP_reg29:
case DW_OP_reg30:
case DW_OP_reg31: {
eval_ctx.loc_desc_kind = Register;
reg_num = opcode - DW_OP_reg0;
if (llvm::Error err = ReadRegisterValueAsScalar(
eval_ctx.reg_ctx, eval_ctx.reg_kind, reg_num, tmp))
return err;
stack.push_back(tmp);
} break;
case DW_OP_regx: {
eval_ctx.loc_desc_kind = Register;
reg_num = op->getRawOperand(0);
Status read_err;
if (llvm::Error err = ReadRegisterValueAsScalar(
eval_ctx.reg_ctx, eval_ctx.reg_kind, reg_num, tmp))
return err;
stack.push_back(tmp);
} break;
case DW_OP_breg0:
case DW_OP_breg1:
case DW_OP_breg2:
case DW_OP_breg3:
case DW_OP_breg4:
case DW_OP_breg5:
case DW_OP_breg6:
case DW_OP_breg7:
case DW_OP_breg8:
case DW_OP_breg9:
case DW_OP_breg10:
case DW_OP_breg11:
case DW_OP_breg12:
case DW_OP_breg13:
case DW_OP_breg14:
case DW_OP_breg15:
case DW_OP_breg16:
case DW_OP_breg17:
case DW_OP_breg18:
case DW_OP_breg19:
case DW_OP_breg20:
case DW_OP_breg21:
case DW_OP_breg22:
case DW_OP_breg23:
case DW_OP_breg24:
case DW_OP_breg25:
case DW_OP_breg26:
case DW_OP_breg27:
case DW_OP_breg28:
case DW_OP_breg29:
case DW_OP_breg30:
case DW_OP_breg31: {
reg_num = opcode - DW_OP_breg0;
if (llvm::Error err = ReadRegisterValueAsScalar(
eval_ctx.reg_ctx, eval_ctx.reg_kind, reg_num, tmp))
return err;
int64_t breg_offset = op->getRawOperand(0);
tmp.GetScalar() = to_generic(tmp.GetScalar().ULongLong());
tmp.GetScalar() += to_generic(breg_offset);
tmp.ClearContext();
stack.push_back(tmp);
stack.back().SetValueType(Value::ValueType::LoadAddress);
} break;
case DW_OP_bregx: {
reg_num = op->getRawOperand(0);
if (llvm::Error err = ReadRegisterValueAsScalar(
eval_ctx.reg_ctx, eval_ctx.reg_kind, reg_num, tmp))
return err;
int64_t breg_offset = op->getRawOperand(1);
tmp.GetScalar() = to_generic(tmp.GetScalar().ULongLong());
tmp.GetScalar() += to_generic(breg_offset);
tmp.ClearContext();
stack.push_back(tmp);
stack.back().SetValueType(Value::ValueType::LoadAddress);
} break;
case DW_OP_fbreg:
if (llvm::Error err =
Evaluate_DW_OP_fbreg(eval_ctx, op->getRawOperand(0)))
return err;
stack.back().GetScalar() =
to_generic(stack.back().GetScalar().ULongLong());
break;
case DW_OP_nop:
break;
case DW_OP_piece: {
if (llvm::Error err =
Evaluate_DW_OP_piece(eval_ctx, op->getRawOperand(0)))
return err;
} break;
case DW_OP_bit_piece:
if (stack.size() < 1) {
UpdateValueTypeFromLocationDescription(eval_ctx,
LocationDescriptionKind::Empty);
// Reset for the next piece.
eval_ctx.loc_desc_kind = Memory;
return llvm::createStringError(
"expression stack needs at least 1 item for DW_OP_bit_piece");
} else {
const LocationDescriptionKind piece_locdesc = eval_ctx.loc_desc_kind;
UpdateValueTypeFromLocationDescription(eval_ctx, piece_locdesc,
&stack.back());
// Reset for the next piece.
eval_ctx.loc_desc_kind = Memory;
const uint64_t piece_bit_size = op->getRawOperand(0);
const uint64_t piece_bit_offset = op->getRawOperand(1);
switch (stack.back().GetValueType()) {
case Value::ValueType::Invalid:
return llvm::createStringError(
"unable to extract bit value from invalid value");
case Value::ValueType::Scalar: {
if (!stack.back().GetScalar().ExtractBitfield(piece_bit_size,
piece_bit_offset)) {
return llvm::createStringError(
"unable to extract %" PRIu64 " bit value with %" PRIu64
" bit offset from a %" PRIu64 " bit scalar value.",
piece_bit_size, piece_bit_offset,
(uint64_t)(stack.back().GetScalar().GetByteSize() * 8));
}
} break;
case Value::ValueType::FileAddress:
case Value::ValueType::LoadAddress:
return llvm::createStringError(
"unable to extract DW_OP_bit_piece(bit_size = %" PRIu64
", bit_offset = %" PRIu64 ") from an address value.",
piece_bit_size, piece_bit_offset);
case Value::ValueType::HostAddress:
// As above, a full-width DW_OP_implicit_value piece refers to the
// backing bytes, not the address of that backing storage.
if (piece_locdesc == Implicit && piece_bit_offset == 0 &&
piece_bit_size % 8 == 0 &&
stack.back().GetBuffer().GetByteSize() == piece_bit_size / 8)
break;
return llvm::createStringError(
"unable to extract DW_OP_bit_piece(bit_size = %" PRIu64
", bit_offset = %" PRIu64 ") from an address value.",
piece_bit_size, piece_bit_offset);
}
}
break;
case DW_OP_implicit_value: {
eval_ctx.loc_desc_kind = Implicit;
// The second operand is a sequence of bytes of the length specified by
// the first operand. LLVM represents it as an offset to that sequence.
const uint64_t block_size = op->getRawOperand(0);
uint64_t block_offset = op->getRawOperand(1);
llvm::Error error = llvm::Error::success();
llvm::StringRef block_data =
expr_data.getBytes(&block_offset, block_size, &error);
if (error)
return error;
Value result(block_data.data(), block_data.size());
stack.push_back(result);
break;
}
case DW_OP_implicit_pointer: {
eval_ctx.loc_desc_kind = Implicit;
return llvm::createStringError("could not evaluate %s",
DW_OP_value_to_name(opcode));
}
case DW_OP_push_object_address:
if (eval_ctx.object_address_ptr)
stack.push_back(*eval_ctx.object_address_ptr);
else {
return llvm::createStringError("DW_OP_push_object_address used without "
"specifying an object address");
}
break;
case DW_OP_stack_value:
eval_ctx.loc_desc_kind = Implicit;
stack.back().SetValueType(Value::ValueType::Scalar);
break;
case DW_OP_convert:
if (llvm::Error err =
Evaluate_DW_OP_convert(eval_ctx, op->getRawOperand(0)))
return err;
break;
case DW_OP_call_frame_cfa:
if (llvm::Error err = Evaluate_DW_OP_call_frame_cfa(eval_ctx))
return err;
stack.back().GetScalar() =
to_generic(stack.back().GetScalar().ULongLong());
break;
case DW_OP_form_tls_address:
case DW_OP_GNU_push_tls_address:
if (llvm::Error err = Evaluate_DW_OP_form_tls_address(eval_ctx, opcode))
return err;
break;
case DW_OP_addrx:
case DW_OP_GNU_addr_index: {
if (!eval_ctx.dwarf_cu)
return llvm::createStringError("DW_OP_GNU_addr_index found without a "
"compile unit being specified");
uint64_t index = op->getRawOperand(0);
lldb::addr_t value =
eval_ctx.dwarf_cu->ReadAddressFromDebugAddrSection(index);
stack.push_back(to_generic(value));
stack.back().SetValueType(Value::ValueType::FileAddress);
} break;
case DW_OP_GNU_const_index: {
if (!eval_ctx.dwarf_cu) {
return llvm::createStringError("DW_OP_GNU_const_index found without a "
"compile unit being specified");
}
uint64_t index = op->getRawOperand(0);
lldb::addr_t value =
eval_ctx.dwarf_cu->ReadAddressFromDebugAddrSection(index);
stack.push_back(to_generic(value));
} break;
case DW_OP_GNU_entry_value:
case DW_OP_entry_value: {
// Technically, DW_OP_entry_value has two operands, but LLVM represents
// it as a single-operand operation (bug?). We can deal with this: the
// second operand immediately follows the first, but have to be careful
// when advancing the iterator, see the comment below.
const uint64_t block_size = op->getRawOperand(0);
uint64_t block_offset = op->getEndOffset();
llvm::Error error = llvm::Error::success();
llvm::ArrayRef<uint8_t> block_data = llvm::arrayRefFromStringRef(
expr_data.getBytes(&block_offset, block_size, &error));
if (error)
return error;
if (llvm::Error err = Evaluate_DW_OP_entry_value(eval_ctx, block_data))
return llvm::createStringError(
"could not evaluate DW_OP_entry_value: %s",
llvm::toString(std::move(err)).c_str());
// We can't use `operator++` here because the iterator currently points
// to the second operand. See the comment above.
op = op.skipBytes(block_size);
continue;
}
// These opcodes are decoded but not evaluated here.
case DW_OP_xderef:
case DW_OP_xderef_size:
case DW_OP_call2:
case DW_OP_call4:
case DW_OP_call_ref:
case DW_OP_constx:
case DW_OP_const_type:
case DW_OP_regval_type:
case DW_OP_deref_type:
case DW_OP_xderef_type:
case DW_OP_reinterpret:
case DW_OP_GNU_implicit_pointer:
return llvm::createStringError("unimplemented opcode %s",
DW_OP_value_to_name(opcode));
case DW_OP_LLVM_user:
if (op->getSubCode() == DW_OP_LLVM_piece_end) {
if (op->getEndOffset() != expr_data.size())
return llvm::createStringError(
"DW_OP_LLVM_piece_end is only supported at the end of an "
"expression");
// LLDB already constructs one composite in `pieces`, so a terminal
// DW_OP_LLVM_piece_end is a no-op. TODO: Support multiple composites
// and DW_OP_piece_end once LLVM implements DWARF 6 locations on the
// stack.
// Extension:
// https://llvm.org/docs/AMDGPUDwarfExtensionsForHeterogeneousDebugging.html
// Standard: https://dwarfstd.org/issues/230524.1-orig.html
break;
}
[[fallthrough]];
default:
if (eval_ctx.dwarf_cu) {
const uint64_t operands_offset = op_offset + 1;
uint64_t offset = operands_offset; // Updated by the callee.
if (eval_ctx.dwarf_cu->ParseVendorDWARFOpcode(
opcode, expr_data, offset, eval_ctx.reg_ctx, eval_ctx.reg_kind,
stack)) {
// This is a little tricky. If LLVM knows about this vendor-specific
// operation, `getEndOffset()` points past its last operand. If LLVM
// knows nothing about this operation, `getEndOffset()` points to its
// opcode. In both cases `offset` will point to the next operation,
// but we can't use it directly because the only available mutating
// method of `iterator` (not counting `operator++`) is `skipBytes()`.
// So we calculate the offset and pass it to `skipBytes()`.
assert(offset >= op->getEndOffset());
uint64_t offset_to_next_op = offset - op->getEndOffset();
op = op.skipBytes(offset_to_next_op);
continue;
}
}
return llvm::createStringErrorV("unhandled opcode {0} in DWARFExpression",
opcode);
}
++op;
}
if (stack.empty()) {
// Nothing on the stack, check if we created a piece value from DW_OP_piece
// or DW_OP_bit_piece opcodes
if (eval_ctx.pieces.GetBuffer().GetByteSize())
return eval_ctx.pieces;
return llvm::createStringError("stack empty after evaluation");
}
UpdateValueTypeFromLocationDescription(eval_ctx, eval_ctx.loc_desc_kind,
&stack.back());
if (log && log->GetVerbose()) {
size_t count = stack.size();
LLDB_LOGF(log, "Stack after operation has %" PRIu64 " values:",
static_cast<uint64_t>(count));
for (size_t i = 0; i < count; ++i) {
StreamString new_value;
new_value.Printf("[%" PRIu64 "]", static_cast<uint64_t>(i));
stack[i].Dump(&new_value);
LLDB_LOGF(log, " %s", new_value.GetData());
}
}
return stack.back();
}
bool DWARFExpression::MatchesOperand(
StackFrame &frame, const Instruction::Operand &operand) const {
using namespace OperandMatchers;
RegisterContextSP reg_ctx_sp = frame.GetRegisterContext();
if (!reg_ctx_sp) {
return false;
}
DataExtractor opcodes(m_data);
lldb::offset_t op_offset = 0;
uint8_t opcode = opcodes.GetU8(&op_offset);
if (opcode == DW_OP_fbreg) {
int64_t offset = opcodes.GetSLEB128(&op_offset);
DWARFExpressionList *fb_expr = frame.GetFrameBaseExpression(nullptr);
if (!fb_expr) {
return false;
}
auto recurse = [&frame, fb_expr](const Instruction::Operand &child) {
return fb_expr->MatchesOperand(frame, child);
};
if (!offset &&
MatchUnaryOp(MatchOpType(Instruction::Operand::Type::Dereference),
recurse)(operand)) {
return true;
}
return MatchUnaryOp(
MatchOpType(Instruction::Operand::Type::Dereference),
MatchBinaryOp(MatchOpType(Instruction::Operand::Type::Sum),
MatchImmOp(offset), recurse))(operand);
}
bool dereference = false;
const RegisterInfo *reg = nullptr;
int64_t offset = 0;
if (opcode >= DW_OP_reg0 && opcode <= DW_OP_reg31) {
reg = reg_ctx_sp->GetRegisterInfo(m_reg_kind, opcode - DW_OP_reg0);
} else if (opcode >= DW_OP_breg0 && opcode <= DW_OP_breg31) {
offset = opcodes.GetSLEB128(&op_offset);
reg = reg_ctx_sp->GetRegisterInfo(m_reg_kind, opcode - DW_OP_breg0);
} else if (opcode == DW_OP_regx) {
uint32_t reg_num = static_cast<uint32_t>(opcodes.GetULEB128(&op_offset));
reg = reg_ctx_sp->GetRegisterInfo(m_reg_kind, reg_num);
} else if (opcode == DW_OP_bregx) {
uint32_t reg_num = static_cast<uint32_t>(opcodes.GetULEB128(&op_offset));
offset = opcodes.GetSLEB128(&op_offset);
reg = reg_ctx_sp->GetRegisterInfo(m_reg_kind, reg_num);
} else {
return false;
}
if (!reg) {
return false;
}
if (dereference) {
if (!offset &&
MatchUnaryOp(MatchOpType(Instruction::Operand::Type::Dereference),
MatchRegOp(*reg))(operand)) {
return true;
}
return MatchUnaryOp(
MatchOpType(Instruction::Operand::Type::Dereference),
MatchBinaryOp(MatchOpType(Instruction::Operand::Type::Sum),
MatchRegOp(*reg), MatchImmOp(offset)))(operand);
} else {
return MatchRegOp(*reg)(operand);
}
}