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llvm-project/lldb/source/Expression/DWARFExpression.cpp
Adrian Prantl 188b0747c1 Support dereferencing a DWARF scalar stack value 
Swift async functions receive function arguments inside a
heap-allocated data structure, similar to how ObjC block captures or
C++ coroutine arguments are implement. In DWARF they are described
relative to an entry value that produces a pointer into that heap
object. At typical location looks like

DW_OP_entry_value [ DW_OP_reg14 ] DW_OP_deref DW_OP_plus_uconst 32 DW_OP_deref

This allows the unwinder (which has special ABI knowledge to restore
the contents of r14) to push the base address onto the stack thus
allowing the deref/offset operations to continue. The result of the
entry value is a scalar, because DW_OP_reg14 is a register location —
as it should be since we want to restore the pointer value contained
in r14 at the beginning of the function and not the historical memory
contents it was pointing to. The entry value should restore the
address, which is still valid, not the contents at function entry.

To make this work, we need to allow LLDB to dereference Scalar stack
results like load addresses, which is what this patch
does. Unfortunately it is difficult to test this in isolation, since
the DWARFExpression unit test doesn't have a process.

Differential Revision: https://reviews.llvm.org/D96549
2021-02-12 16:12:32 -08:00

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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 <inttypes.h>
#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(), m_dwarf_cu(nullptr),
m_reg_kind(eRegisterKindDWARF) {}
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() {}
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
// So first we copy the data into a heap buffer
std::unique_ptr<DataBufferHeap> head_data_up(
new DataBufferHeap(m_data.GetDataStart(), m_data.GetByteSize()));
// Make en encoder so we can write the address into the buffer using the
// correct byte order (endianness)
DataEncoder encoder(head_data_up->GetBytes(), head_data_up->GetByteSize(),
m_data.GetByteOrder(), addr_byte_size);
// Replace the address in the new buffer
if (encoder.PutUnsigned(offset, addr_byte_size, 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(DataBufferSP(head_data_up.release()));
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
// So first we copy the data into a heap buffer
std::shared_ptr<DataBufferHeap> heap_data_sp(
new DataBufferHeap(m_data.GetDataStart(), m_data.GetByteSize()));
// Make en encoder so we can write the address into the buffer using the
// correct byte order (endianness)
DataEncoder encoder(heap_data_sp->GetBytes(), heap_data_sp->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(heap_data_sp);
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_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);
}
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));
};
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;
stack.back().SetValueType(Value::ValueType::LoadAddress);
// Fall through to load address code below...
} LLVM_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);
Status error;
lldb::addr_t pointer_value =
process->ReadPointerFromMemory(pointer_addr, error);
if (pointer_value != LLDB_INVALID_ADDRESS) {
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: {
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: {
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: {
const uint64_t piece_byte_size = opcodes.GetULEB128(&offset);
if (piece_byte_size > 0) {
Value curr_piece;
if (stack.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();
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) {
if (error_ptr)
error_ptr->SetErrorString(
"Expression stack needs at least 1 item for DW_OP_bit_piece.");
return false;
} else {
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: {
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;
}
// 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:
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;
} else {
if (error_ptr)
error_ptr->SetErrorString("Stack empty after evaluation.");
return false;
}
} else {
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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