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fuchsia / third_party / llvm-project / refs/heads/upstream/revert-143408-allow-objc-property-requires-definitions / . / lldb / source / Expression / DWARFExpression.cpp
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//===-- 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
//
//===----------------------------------------------------------------------===//
#include "lldb/Expression/DWARFExpression.h"
#include <cinttypes>
#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/Utility/VMRange.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/DWARFExpression.h"
using namespace lldb;
using namespace lldb_private;
using namespace lldb_private::dwarf;
using namespace lldb_private::plugin::dwarf;
// 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) 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 {};
};
llvm::DIDumpOptions DumpOpts;
DumpOpts.GetNameForDWARFReg = GetRegName;
llvm::DWARFExpression E(m_data.GetAsLLVM(), m_data.GetAddressByteSize());
llvm::DWARFExpressionPrinter::print(&E, s->AsRawOstream(), DumpOpts, nullptr);
}
RegisterKind DWARFExpression::GetRegisterKind() const { return m_reg_kind; }
void DWARFExpression::SetRegisterKind(RegisterKind reg_kind) {
m_reg_kind = reg_kind;
}
static llvm::Error 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.Skip_LEB128(&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::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(std::vector<Value> &stack,
ExecutionContext *exe_ctx,
RegisterContext *reg_ctx,
const DataExtractor &opcodes,
lldb::offset_t &opcode_offset,
Log *log) {
// 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 ((!exe_ctx || !exe_ctx->HasTargetScope()) || !reg_ctx) {
return llvm::createStringError("no exe/reg context");
}
StackFrame *current_frame = exe_ctx->GetFramePtr();
Thread *thread = exe_ctx->GetThreadPtr();
if (!current_frame || !thread)
return llvm::createStringError("no current frame/thread");
Target &target = 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 = *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::createStringError(
llvm::formatv("no call edge for retn-pc = {0:x} in parent frame {1}",
return_pc, parent_func->GetName()));
}
Function *callee_func = call_edge->GetCallee(modlist, parent_exe_ctx);
if (callee_func != 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) == 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 uint32_t subexpr_len = opcodes.GetULEB128(&opcode_offset);
const void *subexpr_data = opcodes.GetData(&opcode_offset, subexpr_len);
if (!subexpr_data)
return llvm::createStringError("subexpr could not be read");
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_len);
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_len) == 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;
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();
}
stack.push_back(*maybe_result);
return llvm::Error::success();
}
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*/
};
/// Adjust value's ValueType according to the kind of location description.
void UpdateValueTypeFromLocationDescription(
Log *log, const DWARFExpression::Delegate *dwarf_cu,
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 (dwarf_cu && dwarf_cu->GetVersion() >= 4) {
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;
}
}
}
} // namespace
/// Helper function to move common code used to resolve a file address and turn
/// into a load address.
///
/// \param exe_ctx Pointer to the execution context
/// \param module_sp shared_ptr contains the module if we have one
/// \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(ExecutionContext *exe_ctx, lldb::ModuleSP &module_sp,
const char *dw_op_type, lldb::addr_t file_addr,
Address &so_addr, bool check_sectionoffset = false) {
if (!module_sp)
return llvm::createStringError("need module to resolve file address for %s",
dw_op_type);
if (!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(exe_ctx->GetTargetPtr());
if (load_addr == LLDB_INVALID_ADDRESS &&
(check_sectionoffset && !so_addr.IsSectionOffset()))
return llvm::createStringError("failed to resolve load address");
return load_addr;
}
/// Helper function to move common code used to load sized data from a uint8_t
/// buffer.
///
/// \param addr_bytes uint8_t buffer containg raw data
/// \param size_addr_bytes how large is the underlying raw data
/// \param byte_order what is the byter order of the underlyig 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);
else
return addr_data.GetAddress(&addr_data_offset);
}
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) {
if (opcodes.GetByteSize() == 0)
return llvm::createStringError(
"no location, value may have been optimized out");
std::vector<Value> stack;
Process *process = nullptr;
StackFrame *frame = nullptr;
Target *target = nullptr;
if (exe_ctx) {
process = exe_ctx->GetProcessPtr();
frame = exe_ctx->GetFramePtr();
target = exe_ctx->GetTargetPtr();
}
if (reg_ctx == nullptr && frame)
reg_ctx = frame->GetRegisterContext().get();
if (initial_value_ptr)
stack.push_back(*initial_value_ptr);
lldb::offset_t offset = 0;
Value tmp;
uint32_t reg_num;
/// Insertion point for evaluating multi-piece expression.
uint64_t op_piece_offset = 0;
Value pieces; // Used for DW_OP_piece
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 * opcodes.GetAddressByteSize(), v,
is_signed, /*implicitTrunc=*/true),
!is_signed));
};
// The default kind is a memory location. This is updated by any
// operation that changes this, such as DW_OP_stack_value, and reset
// by composition operations like DW_OP_piece.
LocationDescriptionKind dwarf4_location_description_kind = Memory;
while (opcodes.ValidOffset(offset)) {
const lldb::offset_t op_offset = offset;
const uint8_t op = opcodes.GetU8(&offset);
if (log && log->GetVerbose()) {
size_t count = stack.size();
LLDB_LOGF(log, "Stack before operation has %" PRIu64 " values:",
(uint64_t)count);
for (size_t i = 0; i < count; ++i) {
StreamString new_value;
new_value.Printf("[%" PRIu64 "]", (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(op));
}
if (std::optional<unsigned> arity =
llvm::dwarf::OperationArity(static_cast<LocationAtom>(op))) {
if (stack.size() < *arity)
return llvm::createStringError(
"%s needs at least %d stack entries (stack has %d entries)",
DW_OP_value_to_name(op), *arity, stack.size());
}
switch (op) {
// The DW_OP_addr operation has a single operand that encodes a machine
// address and whose size is the size of an address on the target machine.
case DW_OP_addr:
stack.push_back(Scalar(opcodes.GetAddress(&offset)));
if (target &&
target->GetArchitecture().GetCore() == ArchSpec::eCore_wasm32) {
// wasm file sections aren't mapped into memory, therefore addresses can
// never point into a file section and are always LoadAddresses.
stack.back().SetValueType(Value::ValueType::LoadAddress);
} else {
stack.back().SetValueType(Value::ValueType::FileAddress);
}
break;
// The DW_OP_addr_sect_offset4 is used for any location expressions in
// shared libraries that have a location like:
// DW_OP_addr(0x1000)
// If this address resides in a shared library, then this virtual address
// won't make sense when it is evaluated in the context of a running
// process where shared libraries have been slid. To account for this, this
// new address type where we can store the section pointer and a 4 byte
// offset.
// case DW_OP_addr_sect_offset4:
// {
// result_type = eResultTypeFileAddress;
// lldb::Section *sect = (lldb::Section
// *)opcodes.GetMaxU64(&offset, sizeof(void *));
// lldb::addr_t sect_offset = opcodes.GetU32(&offset);
//
// Address so_addr (sect, sect_offset);
// lldb::addr_t load_addr = so_addr.GetLoadAddress();
// if (load_addr != LLDB_INVALID_ADDRESS)
// {
// // We successfully resolve a file address to a load
// // address.
// stack.push_back(load_addr);
// break;
// }
// else
// {
// // We were able
// if (error_ptr)
// error_ptr->SetErrorStringWithFormat ("Section %s in
// %s is not currently loaded.\n",
// sect->GetName().AsCString(),
// sect->GetModule()->GetFileSpec().GetFilename().AsCString());
// return false;
// }
// }
// break;
// OPCODE: DW_OP_deref
// OPERANDS: none
// DESCRIPTION: Pops the top stack entry and treats it as an address.
// The value retrieved from that address is pushed. The size of the data
// retrieved from the dereferenced address is the size of an address on the
// target machine.
case DW_OP_deref: {
if (stack.empty())
return llvm::createStringError(
"expression stack empty for DW_OP_deref");
Value::ValueType value_type = stack.back().GetValueType();
switch (value_type) {
case Value::ValueType::HostAddress: {
void *src = (void *)stack.back().GetScalar().ULongLong();
intptr_t ptr;
::memcpy(&ptr, src, sizeof(void *));
stack.back().GetScalar() = ptr;
stack.back().ClearContext();
} break;
case Value::ValueType::FileAddress: {
auto file_addr = stack.back().GetScalar().ULongLong(
LLDB_INVALID_ADDRESS);
Address so_addr;
auto maybe_load_addr = ResolveLoadAddress(
exe_ctx, module_sp, "DW_OP_deref", file_addr, so_addr);
if (!maybe_load_addr)
return maybe_load_addr.takeError();
stack.back().GetScalar() = *maybe_load_addr;
// Fall through to load address promotion code below.
}
[[fallthrough]];
case Value::ValueType::Scalar:
// Promote Scalar to LoadAddress and fall through.
stack.back().SetValueType(Value::ValueType::LoadAddress);
[[fallthrough]];
case Value::ValueType::LoadAddress:
if (exe_ctx) {
if (process) {
lldb::addr_t pointer_addr =
stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
Status error;
lldb::addr_t pointer_value =
process->ReadPointerFromMemory(pointer_addr, error);
if (pointer_value != LLDB_INVALID_ADDRESS) {
if (ABISP abi_sp = process->GetABI())
pointer_value = abi_sp->FixCodeAddress(pointer_value);
stack.back().GetScalar() = pointer_value;
stack.back().ClearContext();
} else {
return llvm::createStringError(
"Failed to dereference pointer from 0x%" PRIx64
" for DW_OP_deref: %s\n",
pointer_addr, error.AsCString());
}
} else {
return llvm::createStringError("NULL process for DW_OP_deref");
}
} else {
return llvm::createStringError(
"NULL execution context for DW_OP_deref");
}
break;
case Value::ValueType::Invalid:
return llvm::createStringError("invalid value type for DW_OP_deref");
}
} break;
// OPCODE: DW_OP_deref_size
// OPERANDS: 1
// 1 - uint8_t that specifies the size of the data to dereference.
// DESCRIPTION: Behaves like the DW_OP_deref operation: it pops the top
// stack entry and treats it as an address. The value retrieved from that
// address is pushed. In the DW_OP_deref_size operation, however, the size
// in bytes of the data retrieved from the dereferenced address is
// specified by the single operand. This operand is a 1-byte unsigned
// integral constant whose value may not be larger than the size of an
// address on the target machine. The data retrieved is zero extended to
// the size of an address on the target machine before being pushed on the
// expression stack.
case DW_OP_deref_size: {
if (stack.empty()) {
return llvm::createStringError(
"expression stack empty for DW_OP_deref_size");
}
uint8_t size = opcodes.GetU8(&offset);
if (size > 8) {
return llvm::createStringError(
"Invalid address size for DW_OP_deref_size: %d\n", size);
}
Value::ValueType value_type = stack.back().GetValueType();
switch (value_type) {
case Value::ValueType::HostAddress: {
void *src = (void *)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;
}
stack.back().GetScalar() = ptr;
stack.back().ClearContext();
} break;
case Value::ValueType::FileAddress: {
auto file_addr =
stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
Address so_addr;
auto maybe_load_addr = ResolveLoadAddress(
exe_ctx, module_sp, "DW_OP_deref_size", 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 (target &&
target->ReadMemory(so_addr, &addr_bytes, size, error,
/*force_live_memory=*/false) == size) {
ObjectFile *objfile = module_sp->GetObjectFile();
stack.back().GetScalar() = DerefSizeExtractDataHelper(
addr_bytes, size, objfile->GetByteOrder(), size);
stack.back().ClearContext();
break;
} else {
return llvm::createStringError(
"Failed to dereference pointer for DW_OP_deref_size: "
"%s\n",
error.AsCString());
}
}
stack.back().GetScalar() = load_addr;
// Fall through to load address promotion code below.
}
[[fallthrough]];
case Value::ValueType::Scalar:
case Value::ValueType::LoadAddress:
if (exe_ctx) {
if (process) {
lldb::addr_t pointer_addr =
stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
uint8_t addr_bytes[sizeof(lldb::addr_t)];
Status error;
if (process->ReadMemory(pointer_addr, &addr_bytes, size, error) ==
size) {
stack.back().GetScalar() =
DerefSizeExtractDataHelper(addr_bytes, sizeof(addr_bytes),
process->GetByteOrder(), size);
stack.back().ClearContext();
} else {
return llvm::createStringError(
"Failed to dereference pointer from 0x%" PRIx64
" for DW_OP_deref: %s\n",
pointer_addr, error.AsCString());
}
} else {
return llvm::createStringError("NULL process for DW_OP_deref_size");
}
} else {
return llvm::createStringError(
"NULL execution context for DW_OP_deref_size");
}
break;
case Value::ValueType::Invalid:
return llvm::createStringError("invalid value for DW_OP_deref_size");
}
} break;
// OPCODE: DW_OP_xderef_size
// OPERANDS: 1
// 1 - uint8_t that specifies the size of the data to dereference.
// DESCRIPTION: Behaves like the DW_OP_xderef operation: the entry at
// the top of the stack is treated as an address. The second stack entry is
// treated as an "address space identifier" for those architectures that
// support multiple address spaces. The top two stack elements are popped,
// a data item is retrieved through an implementation-defined address
// calculation and pushed as the new stack top. In the DW_OP_xderef_size
// operation, however, the size in bytes of the data retrieved from the
// dereferenced address is specified by the single operand. This operand is
// a 1-byte unsigned integral constant whose value may not be larger than
// the size of an address on the target machine. The data retrieved is zero
// extended to the size of an address on the target machine before being
// pushed on the expression stack.
case DW_OP_xderef_size:
return llvm::createStringError("unimplemented opcode: DW_OP_xderef_size");
// OPCODE: DW_OP_xderef
// OPERANDS: none
// DESCRIPTION: Provides an extended dereference mechanism. The entry at
// the top of the stack is treated as an address. The second stack entry is
// treated as an "address space identifier" for those architectures that
// support multiple address spaces. The top two stack elements are popped,
// a data item is retrieved through an implementation-defined address
// calculation and pushed as the new stack top. The size of the data
// retrieved from the dereferenced address is the size of an address on the
// target machine.
case DW_OP_xderef:
return llvm::createStringError("unimplemented opcode: DW_OP_xderef");
// All DW_OP_constXXX opcodes have a single operand as noted below:
//
// Opcode Operand 1
// DW_OP_const1u 1-byte unsigned integer constant
// DW_OP_const1s 1-byte signed integer constant
// DW_OP_const2u 2-byte unsigned integer constant
// DW_OP_const2s 2-byte signed integer constant
// DW_OP_const4u 4-byte unsigned integer constant
// DW_OP_const4s 4-byte signed integer constant
// DW_OP_const8u 8-byte unsigned integer constant
// DW_OP_const8s 8-byte signed integer constant
// DW_OP_constu unsigned LEB128 integer constant
// DW_OP_consts signed LEB128 integer constant
case DW_OP_const1u:
stack.push_back(to_generic(opcodes.GetU8(&offset)));
break;
case DW_OP_const1s:
stack.push_back(to_generic((int8_t)opcodes.GetU8(&offset)));
break;
case DW_OP_const2u:
stack.push_back(to_generic(opcodes.GetU16(&offset)));
break;
case DW_OP_const2s:
stack.push_back(to_generic((int16_t)opcodes.GetU16(&offset)));
break;
case DW_OP_const4u:
stack.push_back(to_generic(opcodes.GetU32(&offset)));
break;
case DW_OP_const4s:
stack.push_back(to_generic((int32_t)opcodes.GetU32(&offset)));
break;
case DW_OP_const8u:
stack.push_back(to_generic(opcodes.GetU64(&offset)));
break;
case DW_OP_const8s:
stack.push_back(to_generic((int64_t)opcodes.GetU64(&offset)));
break;
// These should also use to_generic, but we can't do that due to a
// producer-side bug in llvm. See llvm.org/pr48087.
case DW_OP_constu:
stack.push_back(Scalar(opcodes.GetULEB128(&offset)));
break;
case DW_OP_consts:
stack.push_back(Scalar(opcodes.GetSLEB128(&offset)));
break;
// OPCODE: DW_OP_dup
// OPERANDS: none
// DESCRIPTION: duplicates the value at the top of the stack
case DW_OP_dup:
if (stack.empty()) {
return llvm::createStringError("expression stack empty for DW_OP_dup");
} else
stack.push_back(stack.back());
break;
// OPCODE: DW_OP_drop
// OPERANDS: none
// DESCRIPTION: pops the value at the top of the stack
case DW_OP_drop:
if (stack.empty()) {
return llvm::createStringError("expression stack empty for DW_OP_drop");
} else
stack.pop_back();
break;
// OPCODE: DW_OP_over
// OPERANDS: none
// DESCRIPTION: Duplicates the entry currently second in the stack at
// the top of the stack.
case DW_OP_over:
stack.push_back(stack[stack.size() - 2]);
break;
// OPCODE: DW_OP_pick
// OPERANDS: uint8_t index into the current stack
// DESCRIPTION: The stack entry with the specified index (0 through 255,
// inclusive) is pushed on the stack
case DW_OP_pick: {
uint8_t pick_idx = opcodes.GetU8(&offset);
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;
// OPCODE: DW_OP_swap
// OPERANDS: none
// DESCRIPTION: swaps the top two stack entries. The entry at the top
// of the stack becomes the second stack entry, and the second entry
// becomes the top of the stack
case DW_OP_swap:
tmp = stack.back();
stack.back() = stack[stack.size() - 2];
stack[stack.size() - 2] = tmp;
break;
// OPCODE: DW_OP_rot
// OPERANDS: none
// DESCRIPTION: Rotates the first three stack entries. The entry at
// the top of the stack becomes the third stack entry, the second entry
// becomes the top of the stack, and the third entry becomes the second
// entry.
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;
// OPCODE: DW_OP_abs
// OPERANDS: none
// DESCRIPTION: pops the top stack entry, interprets it as a signed
// value and pushes its absolute value. If the absolute value can not be
// represented, the result is undefined.
case DW_OP_abs:
if (!stack.back().ResolveValue(exe_ctx).AbsoluteValue()) {
return llvm::createStringError(
"failed to take the absolute value of the first stack item");
}
break;
// OPCODE: DW_OP_and
// OPERANDS: none
// DESCRIPTION: pops the top two stack values, performs a bitwise and
// operation on the two, and pushes the result.
case DW_OP_and:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) & tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_div
// OPERANDS: none
// DESCRIPTION: pops the top two stack values, divides the former second
// entry by the former top of the stack using signed division, and pushes
// the result.
case DW_OP_div: {
tmp = stack.back();
if (tmp.ResolveValue(exe_ctx).IsZero())
return llvm::createStringError("divide by zero");
stack.pop_back();
Scalar divisor, dividend;
divisor = tmp.ResolveValue(exe_ctx);
dividend = stack.back().ResolveValue(exe_ctx);
divisor.MakeSigned();
dividend.MakeSigned();
stack.back() = dividend / divisor;
if (!stack.back().ResolveValue(exe_ctx).IsValid())
return llvm::createStringError("divide failed");
} break;
// OPCODE: DW_OP_minus
// OPERANDS: none
// DESCRIPTION: pops the top two stack values, subtracts the former top
// of the stack from the former second entry, and pushes the result.
case DW_OP_minus:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) - tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_mod
// OPERANDS: none
// DESCRIPTION: pops the top two stack values and pushes the result of
// the calculation: former second stack entry modulo the former top of the
// stack.
case DW_OP_mod:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) % tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_mul
// OPERANDS: none
// DESCRIPTION: pops the top two stack entries, multiplies them
// together, and pushes the result.
case DW_OP_mul:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) * tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_neg
// OPERANDS: none
// DESCRIPTION: pops the top stack entry, and pushes its negation.
case DW_OP_neg:
if (!stack.back().ResolveValue(exe_ctx).UnaryNegate())
return llvm::createStringError("unary negate failed");
break;
// OPCODE: DW_OP_not
// OPERANDS: none
// DESCRIPTION: pops the top stack entry, and pushes its bitwise
// complement
case DW_OP_not:
if (!stack.back().ResolveValue(exe_ctx).OnesComplement())
return llvm::createStringError("logical NOT failed");
break;
// OPCODE: DW_OP_or
// OPERANDS: none
// DESCRIPTION: pops the top two stack entries, performs a bitwise or
// operation on the two, and pushes the result.
case DW_OP_or:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) | tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_plus
// OPERANDS: none
// DESCRIPTION: pops the top two stack entries, adds them together, and
// pushes the result.
case DW_OP_plus:
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() += tmp.GetScalar();
break;
// OPCODE: DW_OP_plus_uconst
// OPERANDS: none
// DESCRIPTION: pops the top stack entry, adds it to the unsigned LEB128
// constant operand and pushes the result.
case DW_OP_plus_uconst: {
const uint64_t uconst_value = opcodes.GetULEB128(&offset);
// Implicit conversion from a UINT to a Scalar...
stack.back().GetScalar() += uconst_value;
if (!stack.back().GetScalar().IsValid())
return llvm::createStringError("DW_OP_plus_uconst failed");
} break;
// OPCODE: DW_OP_shl
// OPERANDS: none
// DESCRIPTION: pops the top two stack entries, shifts the former
// second entry left by the number of bits specified by the former top of
// the stack, and pushes the result.
case DW_OP_shl:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) <<= tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_shr
// OPERANDS: none
// DESCRIPTION: pops the top two stack entries, shifts the former second
// entry right logically (filling with zero bits) by the number of bits
// specified by the former top of the stack, and pushes the result.
case DW_OP_shr:
tmp = stack.back();
stack.pop_back();
if (!stack.back().ResolveValue(exe_ctx).ShiftRightLogical(
tmp.ResolveValue(exe_ctx)))
return llvm::createStringError("DW_OP_shr failed");
break;
// OPCODE: DW_OP_shra
// OPERANDS: none
// DESCRIPTION: pops the top two stack entries, shifts the former second
// entry right arithmetically (divide the magnitude by 2, keep the same
// sign for the result) by the number of bits specified by the former top
// of the stack, and pushes the result.
case DW_OP_shra:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) >>= tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_xor
// OPERANDS: none
// DESCRIPTION: pops the top two stack entries, performs the bitwise
// exclusive-or operation on the two, and pushes the result.
case DW_OP_xor:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) ^ tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_skip
// OPERANDS: int16_t
// DESCRIPTION: An unconditional branch. Its single operand is a 2-byte
// signed integer constant. The 2-byte constant is the number of bytes of
// the DWARF expression to skip forward or backward from the current
// operation, beginning after the 2-byte constant.
case DW_OP_skip: {
int16_t skip_offset = (int16_t)opcodes.GetU16(&offset);
lldb::offset_t new_offset = offset + 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 <= opcodes.GetByteSize())
offset = new_offset;
else {
return llvm::createStringError(llvm::formatv(
"Invalid opcode offset in DW_OP_skip: {0}+({1}) > {2}", offset,
skip_offset, opcodes.GetByteSize()));
}
} break;
// OPCODE: DW_OP_bra
// OPERANDS: int16_t
// DESCRIPTION: A conditional branch. Its single operand is a 2-byte
// signed integer constant. This operation pops the top of stack. If the
// value popped is not the constant 0, the 2-byte constant operand is the
// number of bytes of the DWARF expression to skip forward or backward from
// the current operation, beginning after the 2-byte constant.
case DW_OP_bra: {
tmp = stack.back();
stack.pop_back();
int16_t bra_offset = (int16_t)opcodes.GetU16(&offset);
Scalar zero(0);
if (tmp.ResolveValue(exe_ctx) != zero) {
lldb::offset_t new_offset = offset + 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 <= opcodes.GetByteSize())
offset = new_offset;
else {
return llvm::createStringError(llvm::formatv(
"Invalid opcode offset in DW_OP_bra: {0}+({1}) > {2}", offset,
bra_offset, opcodes.GetByteSize()));
}
}
} break;
// OPCODE: DW_OP_eq
// OPERANDS: none
// DESCRIPTION: pops the top two stack values, compares using the
// equals (==) operator.
// STACK RESULT: push the constant value 1 onto the stack if the result
// of the operation is true or the constant value 0 if the result of the
// operation is false.
case DW_OP_eq:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) == tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_ge
// OPERANDS: none
// DESCRIPTION: pops the top two stack values, compares using the
// greater than or equal to (>=) operator.
// STACK RESULT: push the constant value 1 onto the stack if the result
// of the operation is true or the constant value 0 if the result of the
// operation is false.
case DW_OP_ge:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) >= tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_gt
// OPERANDS: none
// DESCRIPTION: pops the top two stack values, compares using the
// greater than (>) operator.
// STACK RESULT: push the constant value 1 onto the stack if the result
// of the operation is true or the constant value 0 if the result of the
// operation is false.
case DW_OP_gt:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) > tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_le
// OPERANDS: none
// DESCRIPTION: pops the top two stack values, compares using the
// less than or equal to (<=) operator.
// STACK RESULT: push the constant value 1 onto the stack if the result
// of the operation is true or the constant value 0 if the result of the
// operation is false.
case DW_OP_le:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) <= tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_lt
// OPERANDS: none
// DESCRIPTION: pops the top two stack values, compares using the
// less than (<) operator.
// STACK RESULT: push the constant value 1 onto the stack if the result
// of the operation is true or the constant value 0 if the result of the
// operation is false.
case DW_OP_lt:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) < tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_ne
// OPERANDS: none
// DESCRIPTION: pops the top two stack values, compares using the
// not equal (!=) operator.
// STACK RESULT: push the constant value 1 onto the stack if the result
// of the operation is true or the constant value 0 if the result of the
// operation is false.
case DW_OP_ne:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) != tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_litn
// OPERANDS: none
// DESCRIPTION: encode the unsigned literal values from 0 through 31.
// STACK RESULT: push the unsigned literal constant value onto the top
// of the stack.
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(op - DW_OP_lit0));
break;
// OPCODE: DW_OP_regN
// OPERANDS: none
// DESCRIPTION: Push the value in register n on the top of the stack.
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: {
dwarf4_location_description_kind = Register;
reg_num = op - DW_OP_reg0;
if (llvm::Error err =
ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, tmp))
return err;
stack.push_back(tmp);
} break;
// OPCODE: DW_OP_regx
// OPERANDS:
// ULEB128 literal operand that encodes the register.
// DESCRIPTION: Push the value in register on the top of the stack.
case DW_OP_regx: {
dwarf4_location_description_kind = Register;
reg_num = opcodes.GetULEB128(&offset);
Status read_err;
if (llvm::Error err =
ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, tmp))
return err;
stack.push_back(tmp);
} break;
// OPCODE: DW_OP_bregN
// OPERANDS:
// SLEB128 offset from register N
// DESCRIPTION: Value is in memory at the address specified by register
// N plus an offset.
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 = op - DW_OP_breg0;
if (llvm::Error err =
ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, tmp))
return err;
int64_t breg_offset = opcodes.GetSLEB128(&offset);
tmp.ResolveValue(exe_ctx) += (uint64_t)breg_offset;
tmp.ClearContext();
stack.push_back(tmp);
stack.back().SetValueType(Value::ValueType::LoadAddress);
} break;
// OPCODE: DW_OP_bregx
// OPERANDS: 2
// ULEB128 literal operand that encodes the register.
// SLEB128 offset from register N
// DESCRIPTION: Value is in memory at the address specified by register
// N plus an offset.
case DW_OP_bregx: {
reg_num = opcodes.GetULEB128(&offset);
if (llvm::Error err =
ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, tmp))
return err;
int64_t breg_offset = opcodes.GetSLEB128(&offset);
tmp.ResolveValue(exe_ctx) += (uint64_t)breg_offset;
tmp.ClearContext();
stack.push_back(tmp);
stack.back().SetValueType(Value::ValueType::LoadAddress);
} break;
case DW_OP_fbreg:
if (exe_ctx) {
if (frame) {
Scalar value;
if (llvm::Error err = frame->GetFrameBaseValue(value))
return err;
int64_t fbreg_offset = opcodes.GetSLEB128(&offset);
value += fbreg_offset;
stack.push_back(value);
stack.back().SetValueType(Value::ValueType::LoadAddress);
} else {
return llvm::createStringError(
"invalid stack frame in context for DW_OP_fbreg opcode");
}
} else {
return llvm::createStringError(
"NULL execution context for DW_OP_fbreg");
}
break;
// OPCODE: DW_OP_nop
// OPERANDS: none
// DESCRIPTION: A place holder. It has no effect on the location stack
// or any of its values.
case DW_OP_nop:
break;
// OPCODE: DW_OP_piece
// OPERANDS: 1
// ULEB128: byte size of the piece
// DESCRIPTION: The operand describes the size in bytes of the piece of
// the object referenced by the DWARF expression whose result is at the top
// of the stack. If the piece is located in a register, but does not occupy
// the entire register, the placement of the piece within that register is
// defined by the ABI.
//
// Many compilers store a single variable in sets of registers, or store a
// variable partially in memory and partially in registers. DW_OP_piece
// provides a way of describing how large a part of a variable a particular
// DWARF expression refers to.
case DW_OP_piece: {
LocationDescriptionKind piece_locdesc = dwarf4_location_description_kind;
// Reset for the next piece.
dwarf4_location_description_kind = Memory;
const uint64_t piece_byte_size = opcodes.GetULEB128(&offset);
if (piece_byte_size > 0) {
Value curr_piece;
if (stack.empty()) {
UpdateValueTypeFromLocationDescription(
log, dwarf_cu, 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);
pieces.AppendDataToHostBuffer(curr_piece);
} else {
Status error;
// Extract the current piece into "curr_piece"
Value curr_piece_source_value(stack.back());
stack.pop_back();
UpdateValueTypeFromLocationDescription(log, dwarf_cu, 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 (target) {
curr_piece_source_value.ConvertToLoadAddress(module_sp.get(),
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 (target) {
if (curr_piece.ResizeData(piece_byte_size) == piece_byte_size) {
if (target->ReadMemory(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: {
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());
}
// Create curr_piece with bit_size. By default Scalar
// grows to the nearest host integer type.
llvm::APInt fail_value(1, 0, false);
llvm::APInt ap_int = scalar.UInt128(fail_value);
assert(ap_int.getBitWidth() >= bit_size);
llvm::ArrayRef<uint64_t> buf{ap_int.getRawData(),
ap_int.getNumWords()};
curr_piece.GetScalar() = Scalar(llvm::APInt(bit_size, buf));
} break;
}
// Check if this is the first piece?
if (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 (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 (pieces.GetBuffer().GetByteSize() != op_piece_offset) {
return llvm::createStringError(
"DW_OP_piece for offset %" PRIu64
" but top of stack is of size %" PRIu64,
op_piece_offset, pieces.GetBuffer().GetByteSize());
}
if (pieces.AppendDataToHostBuffer(curr_piece) == 0)
return llvm::createStringError("failed to append piece data");
}
}
op_piece_offset += piece_byte_size;
}
} break;
case DW_OP_bit_piece: // 0x9d ULEB128 bit size, ULEB128 bit offset (DWARF3);
if (stack.size() < 1) {
UpdateValueTypeFromLocationDescription(log, dwarf_cu,
LocationDescriptionKind::Empty);
// Reset for the next piece.
dwarf4_location_description_kind = Memory;
return llvm::createStringError(
"expression stack needs at least 1 item for DW_OP_bit_piece");
} else {
UpdateValueTypeFromLocationDescription(
log, dwarf_cu, dwarf4_location_description_kind, &stack.back());
// Reset for the next piece.
dwarf4_location_description_kind = Memory;
const uint64_t piece_bit_size = opcodes.GetULEB128(&offset);
const uint64_t piece_bit_offset = opcodes.GetULEB128(&offset);
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:
case Value::ValueType::HostAddress:
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;
// OPCODE: DW_OP_implicit_value
// OPERANDS: 2
// ULEB128 size of the value block in bytes
// uint8_t* block bytes encoding value in target's memory
// representation
// DESCRIPTION: Value is immediately stored in block in the debug info with
// the memory representation of the target.
case DW_OP_implicit_value: {
dwarf4_location_description_kind = Implicit;
const uint32_t len = opcodes.GetULEB128(&offset);
const void *data = opcodes.GetData(&offset, len);
if (!data) {
LLDB_LOG(log, "Evaluate_DW_OP_implicit_value: could not be read data");
return llvm::createStringError("could not evaluate %s",
DW_OP_value_to_name(op));
}
Value result(data, len);
stack.push_back(result);
break;
}
case DW_OP_implicit_pointer: {
dwarf4_location_description_kind = Implicit;
return llvm::createStringError("Could not evaluate %s.",
DW_OP_value_to_name(op));
}
// OPCODE: DW_OP_push_object_address
// OPERANDS: none
// DESCRIPTION: Pushes the address of the object currently being
// evaluated as part of evaluation of a user presented expression. This
// object may correspond to an independent variable described by its own
// DIE or it may be a component of an array, structure, or class whose
// address has been dynamically determined by an earlier step during user
// expression evaluation.
case DW_OP_push_object_address:
if (object_address_ptr)
stack.push_back(*object_address_ptr);
else {
return llvm::createStringError("DW_OP_push_object_address used without "
"specifying an object address");
}
break;
// OPCODE: DW_OP_call2
// OPERANDS:
// uint16_t compile unit relative offset of a DIE
// DESCRIPTION: Performs subroutine calls during evaluation
// of a DWARF expression. The operand is the 2-byte unsigned offset of a
// debugging information entry in the current compilation unit.
//
// Operand interpretation is exactly like that for DW_FORM_ref2.
//
// This operation transfers control of DWARF expression evaluation to the
// DW_AT_location attribute of the referenced DIE. If there is no such
// attribute, then there is no effect. Execution of the DWARF expression of
// a DW_AT_location attribute may add to and/or remove from values on the
// stack. Execution returns to the point following the call when the end of
// the attribute is reached. Values on the stack at the time of the call
// may be used as parameters by the called expression and values left on
// the stack by the called expression may be used as return values by prior
// agreement between the calling and called expressions.
case DW_OP_call2:
return llvm::createStringError("unimplemented opcode DW_OP_call2");
// OPCODE: DW_OP_call4
// OPERANDS: 1
// uint32_t compile unit relative offset of a DIE
// DESCRIPTION: Performs a subroutine call during evaluation of a DWARF
// expression. For DW_OP_call4, the operand is a 4-byte unsigned offset of
// a debugging information entry in the current compilation unit.
//
// Operand interpretation DW_OP_call4 is exactly like that for
// DW_FORM_ref4.
//
// This operation transfers control of DWARF expression evaluation to the
// DW_AT_location attribute of the referenced DIE. If there is no such
// attribute, then there is no effect. Execution of the DWARF expression of
// a DW_AT_location attribute may add to and/or remove from values on the
// stack. Execution returns to the point following the call when the end of
// the attribute is reached. Values on the stack at the time of the call
// may be used as parameters by the called expression and values left on
// the stack by the called expression may be used as return values by prior
// agreement between the calling and called expressions.
case DW_OP_call4:
return llvm::createStringError("unimplemented opcode DW_OP_call4");
// OPCODE: DW_OP_stack_value
// OPERANDS: None
// DESCRIPTION: Specifies that the object does not exist in memory but
// rather is a constant value. The value from the top of the stack is the
// value to be used. This is the actual object value and not the location.
case DW_OP_stack_value:
dwarf4_location_description_kind = Implicit;
stack.back().SetValueType(Value::ValueType::Scalar);
break;
// OPCODE: DW_OP_convert
// OPERANDS: 1
// A ULEB128 that is either a DIE offset of a
// DW_TAG_base_type or 0 for the generic (pointer-sized) type.
//
// DESCRIPTION: Pop the top stack element, convert it to a
// different type, and push the result.
case DW_OP_convert: {
const uint64_t relative_die_offset = opcodes.GetULEB128(&offset);
uint64_t bit_size;
bool sign;
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 (!module_sp)
return llvm::createStringError("no module");
sign = false;
bit_size = module_sp->GetArchitecture().GetAddressByteSize() * 8;
if (!bit_size)
return llvm::createStringError("unspecified architecture");
} else {
auto bit_size_sign_or_err =
dwarf_cu->GetDIEBitSizeAndSign(relative_die_offset);
if (!bit_size_sign_or_err)
return bit_size_sign_or_err.takeError();
bit_size = bit_size_sign_or_err->first;
sign = bit_size_sign_or_err->second;
}
Scalar &top = stack.back().ResolveValue(exe_ctx);
top.TruncOrExtendTo(bit_size, sign);
break;
}
// OPCODE: DW_OP_call_frame_cfa
// OPERANDS: None
// DESCRIPTION: Specifies a DWARF expression that pushes the value of
// the canonical frame address consistent with the call frame information
// located in .debug_frame (or in the FDEs of the eh_frame section).
case DW_OP_call_frame_cfa:
if (frame) {
// Note that we don't have to parse FDEs because this DWARF expression
// is commonly evaluated with a valid stack frame.
StackID id = frame->GetStackID();
addr_t cfa = id.GetCallFrameAddress();
if (cfa != LLDB_INVALID_ADDRESS) {
stack.push_back(Scalar(cfa));
stack.back().SetValueType(Value::ValueType::LoadAddress);
} else {
return llvm::createStringError(
"stack frame does not include a canonical "
"frame address for DW_OP_call_frame_cfa "
"opcode");
}
} else {
return llvm::createStringError("unvalid stack frame in context for "
"DW_OP_call_frame_cfa opcode");
}
break;
// OPCODE: DW_OP_form_tls_address (or the old pre-DWARFv3 vendor extension
// opcode, DW_OP_GNU_push_tls_address)
// OPERANDS: none
// DESCRIPTION: Pops a TLS offset from the stack, converts it to
// an address in the current thread's thread-local storage block, and
// pushes it on the stack.
case DW_OP_form_tls_address:
case DW_OP_GNU_push_tls_address: {
if (stack.size() < 1) {
if (op == DW_OP_form_tls_address)
return llvm::createStringError(
"DW_OP_form_tls_address needs an argument");
else
return llvm::createStringError(
"DW_OP_GNU_push_tls_address needs an argument");
}
if (!exe_ctx || !module_sp)
return llvm::createStringError("no context to evaluate TLS within");
Thread *thread = 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 =
stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
const addr_t tls_load_addr =
thread->GetThreadLocalData(module_sp, tls_file_addr);
if (tls_load_addr == LLDB_INVALID_ADDRESS)
return llvm::createStringError(
"no TLS data currently exists for this thread");
stack.back().GetScalar() = tls_load_addr;
stack.back().SetValueType(Value::ValueType::LoadAddress);
} break;
// OPCODE: DW_OP_addrx (DW_OP_GNU_addr_index is the legacy name.)
// OPERANDS: 1
// ULEB128: index to the .debug_addr section
// DESCRIPTION: Pushes an address to the stack from the .debug_addr
// section with the base address specified by the DW_AT_addr_base attribute
// and the 0 based index is the ULEB128 encoded index.
case DW_OP_addrx:
case DW_OP_GNU_addr_index: {
if (!dwarf_cu)
return llvm::createStringError("DW_OP_GNU_addr_index found without a "
"compile unit being specified");
uint64_t index = opcodes.GetULEB128(&offset);
lldb::addr_t value = dwarf_cu->ReadAddressFromDebugAddrSection(index);
stack.push_back(Scalar(value));
if (target &&
target->GetArchitecture().GetCore() == ArchSpec::eCore_wasm32) {
// wasm file sections aren't mapped into memory, therefore addresses can
// never point into a file section and are always LoadAddresses.
stack.back().SetValueType(Value::ValueType::LoadAddress);
} else {
stack.back().SetValueType(Value::ValueType::FileAddress);
}
} break;
// OPCODE: DW_OP_GNU_const_index
// OPERANDS: 1
// ULEB128: index to the .debug_addr section
// DESCRIPTION: Pushes an constant with the size of a machine address to
// the stack from the .debug_addr section with the base address specified
// by the DW_AT_addr_base attribute and the 0 based index is the ULEB128
// encoded index.
case DW_OP_GNU_const_index: {
if (!dwarf_cu) {
return llvm::createStringError("DW_OP_GNU_const_index found without a "
"compile unit being specified");
}
uint64_t index = opcodes.GetULEB128(&offset);
lldb::addr_t value = dwarf_cu->ReadAddressFromDebugAddrSection(index);
stack.push_back(Scalar(value));
} break;
case DW_OP_GNU_entry_value:
case DW_OP_entry_value: {
if (llvm::Error err = Evaluate_DW_OP_entry_value(stack, exe_ctx, reg_ctx,
opcodes, offset, log))
return llvm::createStringError(
"could not evaluate DW_OP_entry_value: %s",
llvm::toString(std::move(err)).c_str());
break;
}
default:
if (dwarf_cu) {
if (dwarf_cu->ParseVendorDWARFOpcode(op, opcodes, offset, stack)) {
break;
}
}
return llvm::createStringError(llvm::formatv(
"Unhandled opcode {0} in DWARFExpression", LocationAtom(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 (pieces.GetBuffer().GetByteSize())
return pieces;
return llvm::createStringError("stack empty after evaluation");
}
UpdateValueTypeFromLocationDescription(
log, dwarf_cu, dwarf4_location_description_kind, &stack.back());
if (log && log->GetVerbose()) {
size_t count = stack.size();
LLDB_LOGF(log,
"Stack after operation has %" PRIu64 " values:", (uint64_t)count);
for (size_t i = 0; i < count; ++i) {
StreamString new_value;
new_value.Printf("[%" PRIu64 "]", (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);
}
}