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llvm-project/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 <vector>
#include "lldb/Core/Module.h"
#include "lldb/Core/Value.h"
#include "lldb/Core/dwarf.h"
#include "lldb/Utility/DataEncoder.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 "Plugins/SymbolFile/DWARF/DWARFUnit.h"
using namespace lldb;
using namespace lldb_private;
static lldb::addr_t
ReadAddressFromDebugAddrSection(const DWARFUnit *dwarf_cu,
uint32_t index) {
uint32_t index_size = dwarf_cu->GetAddressByteSize();
dw_offset_t addr_base = dwarf_cu->GetAddrBase();
lldb::offset_t offset = addr_base + index * index_size;
const DWARFDataExtractor &data =
dwarf_cu->GetSymbolFileDWARF().GetDWARFContext().getOrLoadAddrData();
if (data.ValidOffsetForDataOfSize(offset, index_size))
return data.GetMaxU64_unchecked(&offset, index_size);
return LLDB_INVALID_ADDRESS;
}
// DWARFExpression constructor
DWARFExpression::DWARFExpression() : m_module_wp(), m_data() {}
DWARFExpression::DWARFExpression(lldb::ModuleSP module_sp,
const DataExtractor &data,
const DWARFUnit *dwarf_cu)
: m_module_wp(), m_data(data), m_dwarf_cu(dwarf_cu),
m_reg_kind(eRegisterKindDWARF) {
if (module_sp)
m_module_wp = module_sp;
}
// 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, const DataExtractor &data,
lldb::DescriptionLevel level,
ABI *abi) const {
llvm::DWARFExpression(data.GetAsLLVM(), data.GetAddressByteSize())
.print(s->AsRawOstream(), llvm::DIDumpOptions(),
abi ? &abi->GetMCRegisterInfo() : nullptr, nullptr);
}
void DWARFExpression::SetLocationListAddresses(addr_t cu_file_addr,
addr_t func_file_addr) {
m_loclist_addresses = LoclistAddresses{cu_file_addr, func_file_addr};
}
int DWARFExpression::GetRegisterKind() { return m_reg_kind; }
void DWARFExpression::SetRegisterKind(RegisterKind reg_kind) {
m_reg_kind = reg_kind;
}
bool DWARFExpression::IsLocationList() const {
return bool(m_loclist_addresses);
}
namespace {
/// Implement enough of the DWARFObject interface in order to be able to call
/// DWARFLocationTable::dumpLocationList. We don't have access to a real
/// DWARFObject here because DWARFExpression is used in non-DWARF scenarios too.
class DummyDWARFObject final: public llvm::DWARFObject {
public:
DummyDWARFObject(bool IsLittleEndian) : IsLittleEndian(IsLittleEndian) {}
bool isLittleEndian() const override { return IsLittleEndian; }
llvm::Optional<llvm::RelocAddrEntry> find(const llvm::DWARFSection &Sec,
uint64_t Pos) const override {
return llvm::None;
}
private:
bool IsLittleEndian;
};
}
void DWARFExpression::GetDescription(Stream *s, lldb::DescriptionLevel level,
addr_t location_list_base_addr,
ABI *abi) const {
if (IsLocationList()) {
// We have a location list
lldb::offset_t offset = 0;
std::unique_ptr<llvm::DWARFLocationTable> loctable_up =
m_dwarf_cu->GetLocationTable(m_data);
llvm::MCRegisterInfo *MRI = abi ? &abi->GetMCRegisterInfo() : nullptr;
llvm::DIDumpOptions DumpOpts;
DumpOpts.RecoverableErrorHandler = [&](llvm::Error E) {
s->AsRawOstream() << "error: " << toString(std::move(E));
};
loctable_up->dumpLocationList(
&offset, s->AsRawOstream(),
llvm::object::SectionedAddress{m_loclist_addresses->cu_file_addr}, MRI,
DummyDWARFObject(m_data.GetByteOrder() == eByteOrderLittle), nullptr,
DumpOpts, s->GetIndentLevel() + 2);
} else {
// We have a normal location that contains DW_OP location opcodes
DumpLocation(s, m_data, level, abi);
}
}
static bool ReadRegisterValueAsScalar(RegisterContext *reg_ctx,
lldb::RegisterKind reg_kind,
uint32_t reg_num, Status *error_ptr,
Value &value) {
if (reg_ctx == nullptr) {
if (error_ptr)
error_ptr->SetErrorString("No register context in frame.\n");
} else {
uint32_t native_reg =
reg_ctx->ConvertRegisterKindToRegisterNumber(reg_kind, reg_num);
if (native_reg == LLDB_INVALID_REGNUM) {
if (error_ptr)
error_ptr->SetErrorStringWithFormat("Unable to convert register "
"kind=%u reg_num=%u to a native "
"register number.\n",
reg_kind, reg_num);
} else {
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));
if (error_ptr)
error_ptr->Clear();
return true;
} else {
// If we get this error, then we need to implement a value buffer in
// the dwarf expression evaluation function...
if (error_ptr)
error_ptr->SetErrorStringWithFormat(
"register %s can't be converted to a scalar value",
reg_info->name);
}
} else {
if (error_ptr)
error_ptr->SetErrorStringWithFormat("register %s is not available",
reg_info->name);
}
}
}
return false;
}
/// 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 offset_t GetOpcodeDataSize(const DataExtractor &data,
const lldb::offset_t data_offset,
const uint8_t op) {
lldb::offset_t offset = data_offset;
switch (op) {
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
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_addrx: // 0xa1 1 ULEB128 index
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_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);
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_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;
}
default:
break;
}
return LLDB_INVALID_OFFSET;
}
lldb::addr_t DWARFExpression::GetLocation_DW_OP_addr(uint32_t op_addr_idx,
bool &error) const {
error = false;
if (IsLocationList())
return LLDB_INVALID_ADDRESS;
lldb::offset_t offset = 0;
uint32_t curr_op_addr_idx = 0;
while (m_data.ValidOffset(offset)) {
const uint8_t op = m_data.GetU8(&offset);
if (op == DW_OP_addr) {
const lldb::addr_t op_file_addr = m_data.GetAddress(&offset);
if (curr_op_addr_idx == op_addr_idx)
return op_file_addr;
else
++curr_op_addr_idx;
} else if (op == DW_OP_GNU_addr_index || op == DW_OP_addrx) {
uint64_t index = m_data.GetULEB128(&offset);
if (curr_op_addr_idx == op_addr_idx) {
if (!m_dwarf_cu) {
error = true;
break;
}
return ReadAddressFromDebugAddrSection(m_dwarf_cu, index);
} else
++curr_op_addr_idx;
} else {
const offset_t op_arg_size = GetOpcodeDataSize(m_data, offset, op);
if (op_arg_size == LLDB_INVALID_OFFSET) {
error = true;
break;
}
offset += op_arg_size;
}
}
return LLDB_INVALID_ADDRESS;
}
bool DWARFExpression::Update_DW_OP_addr(lldb::addr_t file_addr) {
if (IsLocationList())
return false;
lldb::offset_t offset = 0;
while (m_data.ValidOffset(offset)) {
const uint8_t op = 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;
} else {
const offset_t op_arg_size = GetOpcodeDataSize(m_data, offset, op);
if (op_arg_size == LLDB_INVALID_OFFSET)
break;
offset += op_arg_size;
}
}
return false;
}
bool DWARFExpression::ContainsThreadLocalStorage() const {
// We are assuming for now that any thread local variable will not have a
// location list. This has been true for all thread local variables we have
// seen so far produced by any compiler.
if (IsLocationList())
return false;
lldb::offset_t offset = 0;
while (m_data.ValidOffset(offset)) {
const uint8_t op = m_data.GetU8(&offset);
if (op == DW_OP_form_tls_address || op == DW_OP_GNU_push_tls_address)
return true;
const offset_t op_arg_size = GetOpcodeDataSize(m_data, offset, op);
if (op_arg_size == LLDB_INVALID_OFFSET)
return false;
else
offset += op_arg_size;
}
return false;
}
bool DWARFExpression::LinkThreadLocalStorage(
lldb::ModuleSP new_module_sp,
std::function<lldb::addr_t(lldb::addr_t file_addr)> const
&link_address_callback) {
// We are assuming for now that any thread local variable will not have a
// location list. This has been true for all thread local variables we have
// seen so far produced by any compiler.
if (IsLocationList())
return false;
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 uint8_t op = 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 accodingly. 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 offset_t op_arg_size = GetOpcodeDataSize(m_data, offset, op);
if (op_arg_size == LLDB_INVALID_OFFSET)
return false;
else
offset += op_arg_size;
}
}
// If we linked the TLS address correctly, update the module so that when the
// expression is evaluated it can resolve the file address to a load address
// and read the
// TLS data
m_module_wp = new_module_sp;
m_data.SetData(encoder.GetDataBuffer());
return true;
}
bool DWARFExpression::LocationListContainsAddress(addr_t func_load_addr,
lldb::addr_t addr) const {
if (func_load_addr == LLDB_INVALID_ADDRESS || addr == LLDB_INVALID_ADDRESS)
return false;
if (!IsLocationList())
return false;
return GetLocationExpression(func_load_addr, addr) != llvm::None;
}
bool DWARFExpression::DumpLocationForAddress(Stream *s,
lldb::DescriptionLevel level,
addr_t func_load_addr,
addr_t address, ABI *abi) {
if (!IsLocationList()) {
DumpLocation(s, m_data, level, abi);
return true;
}
if (llvm::Optional<DataExtractor> expr =
GetLocationExpression(func_load_addr, address)) {
DumpLocation(s, *expr, level, abi);
return true;
}
return false;
}
static bool Evaluate_DW_OP_entry_value(std::vector<Value> &stack,
ExecutionContext *exe_ctx,
RegisterContext *reg_ctx,
const DataExtractor &opcodes,
lldb::offset_t &opcode_offset,
Status *error_ptr, 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) {
LLDB_LOG(log, "Evaluate_DW_OP_entry_value: no exe/reg context");
return false;
}
StackFrame *current_frame = exe_ctx->GetFramePtr();
Thread *thread = exe_ctx->GetThreadPtr();
if (!current_frame || !thread) {
LLDB_LOG(log, "Evaluate_DW_OP_entry_value: no current frame/thread");
return false;
}
Target &target = exe_ctx->GetTargetRef();
StackFrameSP parent_frame = nullptr;
addr_t return_pc = LLDB_INVALID_ADDRESS;
uint32_t current_frame_idx = current_frame->GetFrameIndex();
uint32_t num_frames = thread->GetStackFrameCount();
for (uint32_t parent_frame_idx = current_frame_idx + 1;
parent_frame_idx < num_frames; ++parent_frame_idx) {
parent_frame = thread->GetStackFrameAtIndex(parent_frame_idx);
// Require a valid sequence of frames.
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,
"Evaluate_DW_OP_entry_value: 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()) {
LLDB_LOG(log, "Evaluate_DW_OP_entry_value: no parent frame with reg ctx");
return false;
}
Function *parent_func =
parent_frame->GetSymbolContext(eSymbolContextFunction).function;
if (!parent_func) {
LLDB_LOG(log, "Evaluate_DW_OP_entry_value: no parent function");
return false;
}
// 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) {
LLDB_LOG(log, "Evaluate_DW_OP_entry_value: no current function");
return false;
}
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) {
LLDB_LOG(log,
"Evaluate_DW_OP_entry_value: no call edge for retn-pc = {0:x} "
"in parent frame {1}",
return_pc, parent_func->GetName());
return false;
}
Function *callee_func = call_edge->GetCallee(modlist, parent_exe_ctx);
if (callee_func != current_func) {
LLDB_LOG(log, "Evaluate_DW_OP_entry_value: ambiguous call sequence, "
"can't find real parent frame");
return false;
}
} 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) {
LLDB_LOG(log, "Evaluate_DW_OP_entry_value: no unambiguous edge from parent "
"to current function");
return false;
}
// 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) {
LLDB_LOG(log, "Evaluate_DW_OP_entry_value: subexpr could not be read");
return false;
}
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) {
LLDB_LOG(log,
"Evaluate_DW_OP_entry_value: no matching call site param found");
return false;
}
// TODO: Add support for DW_OP_push_object_address within a DW_OP_entry_value
// subexpresion whenever llvm does.
Value result;
const DWARFExpression &param_expr = matched_param->LocationInCaller;
if (!param_expr.Evaluate(&parent_exe_ctx,
parent_frame->GetRegisterContext().get(),
/*loclist_base_load_addr=*/LLDB_INVALID_ADDRESS,
/*initial_value_ptr=*/nullptr,
/*object_address_ptr=*/nullptr, result, error_ptr)) {
LLDB_LOG(log,
"Evaluate_DW_OP_entry_value: call site param evaluation failed");
return false;
}
stack.push_back(result);
return true;
}
bool DWARFExpression::Evaluate(ExecutionContextScope *exe_scope,
lldb::addr_t loclist_base_load_addr,
const Value *initial_value_ptr,
const Value *object_address_ptr, Value &result,
Status *error_ptr) const {
ExecutionContext exe_ctx(exe_scope);
return Evaluate(&exe_ctx, nullptr, loclist_base_load_addr, initial_value_ptr,
object_address_ptr, result, error_ptr);
}
bool DWARFExpression::Evaluate(ExecutionContext *exe_ctx,
RegisterContext *reg_ctx,
lldb::addr_t func_load_addr,
const Value *initial_value_ptr,
const Value *object_address_ptr, Value &result,
Status *error_ptr) const {
ModuleSP module_sp = m_module_wp.lock();
if (IsLocationList()) {
addr_t pc;
StackFrame *frame = nullptr;
if (reg_ctx)
pc = reg_ctx->GetPC();
else {
frame = exe_ctx->GetFramePtr();
if (!frame)
return false;
RegisterContextSP reg_ctx_sp = frame->GetRegisterContext();
if (!reg_ctx_sp)
return false;
pc = reg_ctx_sp->GetPC();
}
if (func_load_addr != LLDB_INVALID_ADDRESS) {
if (pc == LLDB_INVALID_ADDRESS) {
if (error_ptr)
error_ptr->SetErrorString("Invalid PC in frame.");
return false;
}
if (llvm::Optional<DataExtractor> expr =
GetLocationExpression(func_load_addr, pc)) {
return DWARFExpression::Evaluate(
exe_ctx, reg_ctx, module_sp, *expr, m_dwarf_cu, m_reg_kind,
initial_value_ptr, object_address_ptr, result, error_ptr);
}
}
if (error_ptr)
error_ptr->SetErrorString("variable not available");
return false;
}
// Not a location list, just a single expression.
return DWARFExpression::Evaluate(exe_ctx, reg_ctx, module_sp, m_data,
m_dwarf_cu, m_reg_kind, initial_value_ptr,
object_address_ptr, result, error_ptr);
}
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 DWARFUnit *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 DWARFExpresssion::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
bool DWARFExpression::Evaluate(
ExecutionContext *exe_ctx, RegisterContext *reg_ctx,
lldb::ModuleSP module_sp, const DataExtractor &opcodes,
const DWARFUnit *dwarf_cu, const lldb::RegisterKind reg_kind,
const Value *initial_value_ptr, const Value *object_address_ptr,
Value &result, Status *error_ptr) {
if (opcodes.GetByteSize() == 0) {
if (error_ptr)
error_ptr->SetErrorString(
"no location, value may have been optimized out");
return false;
}
std::vector<Value> stack;
Process *process = nullptr;
StackFrame *frame = nullptr;
if (exe_ctx) {
process = exe_ctx->GetProcessPtr();
frame = exe_ctx->GetFramePtr();
}
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(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_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) {
bool is_signed = std::is_signed<decltype(v)>::value;
return Scalar(llvm::APSInt(
llvm::APInt(8 * opcodes.GetAddressByteSize(), v, is_signed),
!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));
}
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)));
stack.back().SetValueType(Value::ValueType::FileAddress);
// Convert the file address to a load address, so subsequent
// DWARF operators can operate on it.
if (frame)
stack.back().ConvertToLoadAddress(module_sp.get(),
frame->CalculateTarget().get());
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()) {
if (error_ptr)
error_ptr->SetErrorString("Expression stack empty for DW_OP_deref.");
return false;
}
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);
if (!module_sp) {
if (error_ptr)
error_ptr->SetErrorString(
"need module to resolve file address for DW_OP_deref");
return false;
}
Address so_addr;
if (!module_sp->ResolveFileAddress(file_addr, so_addr)) {
if (error_ptr)
error_ptr->SetErrorString(
"failed to resolve file address in module");
return false;
}
addr_t load_Addr = so_addr.GetLoadAddress(exe_ctx->GetTargetPtr());
if (load_Addr == LLDB_INVALID_ADDRESS) {
if (error_ptr)
error_ptr->SetErrorString("failed to resolve load address");
return false;
}
stack.back().GetScalar() = load_Addr;
// Fall through to load address promotion code below.
} LLVM_FALLTHROUGH;
case Value::ValueType::Scalar:
// Promote Scalar to LoadAddress and fall through.
stack.back().SetValueType(Value::ValueType::LoadAddress);
LLVM_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 {
if (error_ptr)
error_ptr->SetErrorStringWithFormat(
"Failed to dereference pointer from 0x%" PRIx64
" for DW_OP_deref: %s\n",
pointer_addr, error.AsCString());
return false;
}
} else {
if (error_ptr)
error_ptr->SetErrorString("NULL process for DW_OP_deref.\n");
return false;
}
} else {
if (error_ptr)
error_ptr->SetErrorString(
"NULL execution context for DW_OP_deref.\n");
return false;
}
break;
case Value::ValueType::Invalid:
if (error_ptr)
error_ptr->SetErrorString("Invalid value type for DW_OP_deref.\n");
return false;
}
} 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()) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack empty for DW_OP_deref_size.");
return false;
}
uint8_t size = opcodes.GetU8(&offset);
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::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) {
DataExtractor addr_data(addr_bytes, sizeof(addr_bytes),
process->GetByteOrder(), size);
lldb::offset_t addr_data_offset = 0;
switch (size) {
case 1:
stack.back().GetScalar() = addr_data.GetU8(&addr_data_offset);
break;
case 2:
stack.back().GetScalar() = addr_data.GetU16(&addr_data_offset);
break;
case 4:
stack.back().GetScalar() = addr_data.GetU32(&addr_data_offset);
break;
case 8:
stack.back().GetScalar() = addr_data.GetU64(&addr_data_offset);
break;
default:
stack.back().GetScalar() =
addr_data.GetAddress(&addr_data_offset);
}
stack.back().ClearContext();
} else {
if (error_ptr)
error_ptr->SetErrorStringWithFormat(
"Failed to dereference pointer from 0x%" PRIx64
" for DW_OP_deref: %s\n",
pointer_addr, error.AsCString());
return false;
}
} else {
if (error_ptr)
error_ptr->SetErrorString("NULL process for DW_OP_deref_size.\n");
return false;
}
} else {
if (error_ptr)
error_ptr->SetErrorString(
"NULL execution context for DW_OP_deref_size.\n");
return false;
}
break;
case Value::ValueType::FileAddress:
case Value::ValueType::Invalid:
if (error_ptr)
error_ptr->SetErrorString("Invalid value for DW_OP_deref_size.\n");
return false;
}
} 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:
if (error_ptr)
error_ptr->SetErrorString("Unimplemented opcode: DW_OP_xderef_size.");
return false;
// 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:
if (error_ptr)
error_ptr->SetErrorString("Unimplemented opcode: DW_OP_xderef.");
return false;
// 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()) {
if (error_ptr)
error_ptr->SetErrorString("Expression stack empty for DW_OP_dup.");
return false;
} 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()) {
if (error_ptr)
error_ptr->SetErrorString("Expression stack empty for DW_OP_drop.");
return false;
} 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:
if (stack.size() < 2) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 2 items for DW_OP_over.");
return false;
} else
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 {
if (error_ptr)
error_ptr->SetErrorStringWithFormat(
"Index %u out of range for DW_OP_pick.\n", pick_idx);
return false;
}
} 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:
if (stack.size() < 2) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 2 items for DW_OP_swap.");
return false;
} else {
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:
if (stack.size() < 3) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 3 items for DW_OP_rot.");
return false;
} else {
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.empty()) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 1 item for DW_OP_abs.");
return false;
} else if (!stack.back().ResolveValue(exe_ctx).AbsoluteValue()) {
if (error_ptr)
error_ptr->SetErrorString(
"Failed to take the absolute value of the first stack item.");
return false;
}
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:
if (stack.size() < 2) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 2 items for DW_OP_and.");
return false;
} else {
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:
if (stack.size() < 2) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 2 items for DW_OP_div.");
return false;
} else {
tmp = stack.back();
if (tmp.ResolveValue(exe_ctx).IsZero()) {
if (error_ptr)
error_ptr->SetErrorString("Divide by zero.");
return false;
} else {
stack.pop_back();
stack.back() =
stack.back().ResolveValue(exe_ctx) / tmp.ResolveValue(exe_ctx);
if (!stack.back().ResolveValue(exe_ctx).IsValid()) {
if (error_ptr)
error_ptr->SetErrorString("Divide failed.");
return false;
}
}
}
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:
if (stack.size() < 2) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 2 items for DW_OP_minus.");
return false;
} else {
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:
if (stack.size() < 2) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 2 items for DW_OP_mod.");
return false;
} else {
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:
if (stack.size() < 2) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 2 items for DW_OP_mul.");
return false;
} else {
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.empty()) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 1 item for DW_OP_neg.");
return false;
} else {
if (!stack.back().ResolveValue(exe_ctx).UnaryNegate()) {
if (error_ptr)
error_ptr->SetErrorString("Unary negate failed.");
return false;
}
}
break;
// OPCODE: DW_OP_not
// OPERANDS: none
// DESCRIPTION: pops the top stack entry, and pushes its bitwise
// complement
case DW_OP_not:
if (stack.empty()) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 1 item for DW_OP_not.");
return false;
} else {
if (!stack.back().ResolveValue(exe_ctx).OnesComplement()) {
if (error_ptr)
error_ptr->SetErrorString("Logical NOT failed.");
return false;
}
}
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:
if (stack.size() < 2) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 2 items for DW_OP_or.");
return false;
} else {
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:
if (stack.size() < 2) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 2 items for DW_OP_plus.");
return false;
} else {
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:
if (stack.empty()) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 1 item for DW_OP_plus_uconst.");
return false;
} else {
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()) {
if (error_ptr)
error_ptr->SetErrorString("DW_OP_plus_uconst failed.");
return false;
}
}
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:
if (stack.size() < 2) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 2 items for DW_OP_shl.");
return false;
} else {
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:
if (stack.size() < 2) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 2 items for DW_OP_shr.");
return false;
} else {
tmp = stack.back();
stack.pop_back();
if (!stack.back().ResolveValue(exe_ctx).ShiftRightLogical(
tmp.ResolveValue(exe_ctx))) {
if (error_ptr)
error_ptr->SetErrorString("DW_OP_shr failed.");
return false;
}
}
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:
if (stack.size() < 2) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 2 items for DW_OP_shra.");
return false;
} else {
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:
if (stack.size() < 2) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 2 items for DW_OP_xor.");
return false;
} else {
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;
if (opcodes.ValidOffset(new_offset))
offset = new_offset;
else {
if (error_ptr)
error_ptr->SetErrorString("Invalid opcode offset in DW_OP_skip.");
return false;
}
} 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:
if (stack.empty()) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 1 item for DW_OP_bra.");
return false;
} else {
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;
if (opcodes.ValidOffset(new_offset))
offset = new_offset;
else {
if (error_ptr)
error_ptr->SetErrorString("Invalid opcode offset in DW_OP_bra.");
return false;
}
}
}
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:
if (stack.size() < 2) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 2 items for DW_OP_eq.");
return false;
} else {
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:
if (stack.size() < 2) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 2 items for DW_OP_ge.");
return false;
} else {
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:
if (stack.size() < 2) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 2 items for DW_OP_gt.");
return false;
} else {
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:
if (stack.size() < 2) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 2 items for DW_OP_le.");
return false;
} else {
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:
if (stack.size() < 2) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 2 items for DW_OP_lt.");
return false;
} else {
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:
if (stack.size() < 2) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 2 items for DW_OP_ne.");
return false;
} else {
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 (ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, error_ptr, tmp))
stack.push_back(tmp);
else
return false;
} 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);
if (ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, error_ptr, tmp))
stack.push_back(tmp);
else
return false;
} 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 (ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, error_ptr,
tmp)) {
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);
} else
return false;
} 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 (ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, error_ptr,
tmp)) {
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);
} else
return false;
} break;
case DW_OP_fbreg:
if (exe_ctx) {
if (frame) {
Scalar value;
if (frame->GetFrameBaseValue(value, error_ptr)) {
int64_t fbreg_offset = opcodes.GetSLEB128(&offset);
value += fbreg_offset;
stack.push_back(value);
stack.back().SetValueType(Value::ValueType::LoadAddress);
} else
return false;
} else {
if (error_ptr)
error_ptr->SetErrorString(
"Invalid stack frame in context for DW_OP_fbreg opcode.");
return false;
}
} else {
if (error_ptr)
error_ptr->SetErrorString(
"NULL execution context for DW_OP_fbreg.\n");
return false;
}
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();
switch (curr_piece_source_value_type) {
case Value::ValueType::Invalid:
return false;
case Value::ValueType::LoadAddress:
if (process) {
if (curr_piece.ResizeData(piece_byte_size) == piece_byte_size) {
lldb::addr_t load_addr =
curr_piece_source_value.GetScalar().ULongLong(
LLDB_INVALID_ADDRESS);
if (process->ReadMemory(
load_addr, curr_piece.GetBuffer().GetBytes(),
piece_byte_size, error) != piece_byte_size) {
if (error_ptr)
error_ptr->SetErrorStringWithFormat(
"failed to read memory DW_OP_piece(%" PRIu64
") from 0x%" PRIx64,
piece_byte_size, load_addr);
return false;
}
} else {
if (error_ptr)
error_ptr->SetErrorStringWithFormat(
"failed to resize the piece memory buffer for "
"DW_OP_piece(%" PRIu64 ")",
piece_byte_size);
return false;
}
}
break;
case Value::ValueType::FileAddress:
case Value::ValueType::HostAddress:
if (error_ptr) {
lldb::addr_t addr = curr_piece_source_value.GetScalar().ULongLong(
LLDB_INVALID_ADDRESS);
error_ptr->SetErrorStringWithFormat(
"failed to read memory DW_OP_piece(%" PRIu64
") from %s address 0x%" PRIx64,
piece_byte_size, curr_piece_source_value.GetValueType() ==
Value::ValueType::FileAddress
? "file"
: "host",
addr);
}
return false;
case Value::ValueType::Scalar: {
uint32_t bit_size = piece_byte_size * 8;
uint32_t bit_offset = 0;
Scalar &scalar = curr_piece_source_value.GetScalar();
if (!scalar.ExtractBitfield(
bit_size, bit_offset)) {
if (error_ptr)
error_ptr->SetErrorStringWithFormat(
"unable to extract %" PRIu64 " bytes from a %" PRIu64
" byte scalar value.",
piece_byte_size,
(uint64_t)curr_piece_source_value.GetScalar()
.GetByteSize());
return false;
}
// 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) {
if (error_ptr)
error_ptr->SetErrorString("failed to append piece data");
return false;
}
} else {
// If this is the second or later piece there should be a value on
// the stack.
if (pieces.GetBuffer().GetByteSize() != op_piece_offset) {
if (error_ptr)
error_ptr->SetErrorStringWithFormat(
"DW_OP_piece for offset %" PRIu64
" but top of stack is of size %" PRIu64,
op_piece_offset, pieces.GetBuffer().GetByteSize());
return false;
}
if (pieces.AppendDataToHostBuffer(curr_piece) == 0) {
if (error_ptr)
error_ptr->SetErrorString("failed to append piece data");
return false;
}
}
}
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;
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 1 item for DW_OP_bit_piece.");
return false;
} 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 false;
case Value::ValueType::Scalar: {
if (!stack.back().GetScalar().ExtractBitfield(piece_bit_size,
piece_bit_offset)) {
if (error_ptr)
error_ptr->SetErrorStringWithFormat(
"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));
return false;
}
} break;
case Value::ValueType::FileAddress:
case Value::ValueType::LoadAddress:
case Value::ValueType::HostAddress:
if (error_ptr) {
error_ptr->SetErrorStringWithFormat(
"unable to extract DW_OP_bit_piece(bit_size = %" PRIu64
", bit_offset = %" PRIu64 ") from an address value.",
piece_bit_size, piece_bit_offset);
}
return false;
}
}
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");
LLDB_ERRORF(error_ptr, "Could not evaluate %s.",
DW_OP_value_to_name(op));
return false;
}
Value result(data, len);
stack.push_back(result);
break;
}
case DW_OP_implicit_pointer: {
dwarf4_location_description_kind = Implicit;
LLDB_ERRORF(error_ptr, "Could not evaluate %s.", DW_OP_value_to_name(op));
return false;
}
// 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 {
if (error_ptr)
error_ptr->SetErrorString("DW_OP_push_object_address used without "
"specifying an object address");
return false;
}
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:
if (error_ptr)
error_ptr->SetErrorString("Unimplemented opcode DW_OP_call2.");
return false;
// 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:
if (error_ptr)
error_ptr->SetErrorString("Unimplemented opcode DW_OP_call4.");
return false;
// 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;
if (stack.empty()) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 1 item for DW_OP_stack_value.");
return false;
}
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: {
if (stack.size() < 1) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 1 item for DW_OP_convert.");
return false;
}
const uint64_t die_offset = opcodes.GetULEB128(&offset);
uint64_t bit_size;
bool sign;
if (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) {
if (error_ptr)
error_ptr->SetErrorString("No module");
return false;
}
sign = false;
bit_size = module_sp->GetArchitecture().GetAddressByteSize() * 8;
if (!bit_size) {
if (error_ptr)
error_ptr->SetErrorString("unspecified architecture");
return false;
}
} else {
// Retrieve the type DIE that the value is being converted to.
// FIXME: the constness has annoying ripple effects.
DWARFDIE die = const_cast<DWARFUnit *>(dwarf_cu)->GetDIE(die_offset);
if (!die) {
if (error_ptr)
error_ptr->SetErrorString("Cannot resolve DW_OP_convert type DIE");
return false;
}
uint64_t encoding =
die.GetAttributeValueAsUnsigned(DW_AT_encoding, DW_ATE_hi_user);
bit_size = die.GetAttributeValueAsUnsigned(DW_AT_byte_size, 0) * 8;
if (!bit_size)
bit_size = die.GetAttributeValueAsUnsigned(DW_AT_bit_size, 0);
if (!bit_size) {
if (error_ptr)
error_ptr->SetErrorString("Unsupported type size in DW_OP_convert");
return false;
}
switch (encoding) {
case DW_ATE_signed:
case DW_ATE_signed_char:
sign = true;
break;
case DW_ATE_unsigned:
case DW_ATE_unsigned_char:
sign = false;
break;
default:
if (error_ptr)
error_ptr->SetErrorString("Unsupported encoding in DW_OP_convert");
return false;
}
}
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 if (error_ptr)
error_ptr->SetErrorString("Stack frame does not include a canonical "
"frame address for DW_OP_call_frame_cfa "
"opcode.");
} else {
if (error_ptr)
error_ptr->SetErrorString("Invalid stack frame in context for "
"DW_OP_call_frame_cfa opcode.");
return false;
}
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 (error_ptr) {
if (op == DW_OP_form_tls_address)
error_ptr->SetErrorString(
"DW_OP_form_tls_address needs an argument.");
else
error_ptr->SetErrorString(
"DW_OP_GNU_push_tls_address needs an argument.");
}
return false;
}
if (!exe_ctx || !module_sp) {
if (error_ptr)
error_ptr->SetErrorString("No context to evaluate TLS within.");
return false;
}
Thread *thread = exe_ctx->GetThreadPtr();
if (!thread) {
if (error_ptr)
error_ptr->SetErrorString("No thread to evaluate TLS within.");
return false;
}
// 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) {
if (error_ptr)
error_ptr->SetErrorString(
"No TLS data currently exists for this thread.");
return false;
}
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) {
if (error_ptr)
error_ptr->SetErrorString("DW_OP_GNU_addr_index found without a "
"compile unit being specified");
return false;
}
uint64_t index = opcodes.GetULEB128(&offset);
lldb::addr_t value = ReadAddressFromDebugAddrSection(dwarf_cu, index);
stack.push_back(Scalar(value));
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) {
if (error_ptr)
error_ptr->SetErrorString("DW_OP_GNU_const_index found without a "
"compile unit being specified");
return false;
}
uint64_t index = opcodes.GetULEB128(&offset);
lldb::addr_t value = ReadAddressFromDebugAddrSection(dwarf_cu, index);
stack.push_back(Scalar(value));
} break;
case DW_OP_GNU_entry_value:
case DW_OP_entry_value: {
if (!Evaluate_DW_OP_entry_value(stack, exe_ctx, reg_ctx, opcodes, offset,
error_ptr, log)) {
LLDB_ERRORF(error_ptr, "Could not evaluate %s.",
DW_OP_value_to_name(op));
return false;
}
break;
}
default:
if (error_ptr)
error_ptr->SetErrorStringWithFormatv(
"Unhandled opcode {0} in DWARFExpression", LocationAtom(op));
return false;
}
}
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()) {
result = pieces;
return true;
}
if (error_ptr)
error_ptr->SetErrorString("Stack empty after evaluation.");
return false;
}
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());
}
}
result = stack.back();
return true; // Return true on success
}
static DataExtractor ToDataExtractor(const llvm::DWARFLocationExpression &loc,
ByteOrder byte_order, uint32_t addr_size) {
auto buffer_sp =
std::make_shared<DataBufferHeap>(loc.Expr.data(), loc.Expr.size());
return DataExtractor(buffer_sp, byte_order, addr_size);
}
llvm::Optional<DataExtractor>
DWARFExpression::GetLocationExpression(addr_t load_function_start,
addr_t addr) const {
Log *log = GetLogIfAllCategoriesSet(LIBLLDB_LOG_EXPRESSIONS);
std::unique_ptr<llvm::DWARFLocationTable> loctable_up =
m_dwarf_cu->GetLocationTable(m_data);
llvm::Optional<DataExtractor> result;
uint64_t offset = 0;
auto lookup_addr =
[&](uint32_t index) -> llvm::Optional<llvm::object::SectionedAddress> {
addr_t address = ReadAddressFromDebugAddrSection(m_dwarf_cu, index);
if (address == LLDB_INVALID_ADDRESS)
return llvm::None;
return llvm::object::SectionedAddress{address};
};
auto process_list = [&](llvm::Expected<llvm::DWARFLocationExpression> loc) {
if (!loc) {
LLDB_LOG_ERROR(log, loc.takeError(), "{0}");
return true;
}
if (loc->Range) {
// This relocates low_pc and high_pc by adding the difference between the
// function file address, and the actual address it is loaded in memory.
addr_t slide = load_function_start - m_loclist_addresses->func_file_addr;
loc->Range->LowPC += slide;
loc->Range->HighPC += slide;
if (loc->Range->LowPC <= addr && addr < loc->Range->HighPC)
result = ToDataExtractor(*loc, m_data.GetByteOrder(),
m_data.GetAddressByteSize());
}
return !result;
};
llvm::Error E = loctable_up->visitAbsoluteLocationList(
offset, llvm::object::SectionedAddress{m_loclist_addresses->cu_file_addr},
lookup_addr, process_list);
if (E)
LLDB_LOG_ERROR(log, std::move(E), "{0}");
return result;
}
bool DWARFExpression::MatchesOperand(StackFrame &frame,
const Instruction::Operand &operand) {
using namespace OperandMatchers;
RegisterContextSP reg_ctx_sp = frame.GetRegisterContext();
if (!reg_ctx_sp) {
return false;
}
DataExtractor opcodes;
if (IsLocationList()) {
SymbolContext sc = frame.GetSymbolContext(eSymbolContextFunction);
if (!sc.function)
return false;
addr_t load_function_start =
sc.function->GetAddressRange().GetBaseAddress().GetFileAddress();
if (load_function_start == LLDB_INVALID_ADDRESS)
return false;
addr_t pc = frame.GetFrameCodeAddress().GetLoadAddress(
frame.CalculateTarget().get());
if (llvm::Optional<DataExtractor> expr = GetLocationExpression(load_function_start, pc))
opcodes = std::move(*expr);
else
return false;
} else
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);
DWARFExpression *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);
}
}
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