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clang-p2996/lldb/source/Expression/DWARFExpression.cpp
Nikita Popov 255a99c29f [APInt] Fix APInt constructions where value does not fit bitwidth (NFCI) (#80309) 
This fixes all the places that hit the new assertion added in
https://github.com/llvm/llvm-project/pull/106524 in tests. That is,
cases where the value passed to the APInt constructor is not an N-bit
signed/unsigned integer, where N is the bit width and signedness is
determined by the isSigned flag.

The fixes either set the correct value for isSigned, set the
implicitTrunc flag, or perform more calculations inside APInt.

Note that the assertion is currently still disabled by default, so this
patch is mostly NFC.
2024-10-17 08:48:08 +02:00

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92 KiB
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//===-- DWARFExpression.cpp -----------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "lldb/Expression/DWARFExpression.h"
#include <cinttypes>
#include <optional>
#include <vector>
#include "lldb/Core/Module.h"
#include "lldb/Core/Value.h"
#include "lldb/Core/dwarf.h"
#include "lldb/Utility/DataEncoder.h"
#include "lldb/Utility/LLDBLog.h"
#include "lldb/Utility/Log.h"
#include "lldb/Utility/RegisterValue.h"
#include "lldb/Utility/Scalar.h"
#include "lldb/Utility/StreamString.h"
#include "lldb/Utility/VMRange.h"
#include "lldb/Host/Host.h"
#include "lldb/Utility/Endian.h"
#include "lldb/Symbol/Function.h"
#include "lldb/Target/ABI.h"
#include "lldb/Target/ExecutionContext.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Target/StackFrame.h"
#include "lldb/Target/StackID.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/Thread.h"
#include "llvm/DebugInfo/DWARF/DWARFDebugLoc.h"
#include "llvm/DebugInfo/DWARF/DWARFExpression.h"
#include "Plugins/SymbolFile/DWARF/DWARFUnit.h"
using namespace lldb;
using namespace lldb_private;
using namespace lldb_private::dwarf;
using namespace lldb_private::plugin::dwarf;
// DWARFExpression constructor
DWARFExpression::DWARFExpression() : m_data() {}
DWARFExpression::DWARFExpression(const DataExtractor &data) : m_data(data) {}
// Destructor
DWARFExpression::~DWARFExpression() = default;
bool DWARFExpression::IsValid() const { return m_data.GetByteSize() > 0; }
void DWARFExpression::UpdateValue(uint64_t const_value,
lldb::offset_t const_value_byte_size,
uint8_t addr_byte_size) {
if (!const_value_byte_size)
return;
m_data.SetData(
DataBufferSP(new DataBufferHeap(&const_value, const_value_byte_size)));
m_data.SetByteOrder(endian::InlHostByteOrder());
m_data.SetAddressByteSize(addr_byte_size);
}
void DWARFExpression::DumpLocation(Stream *s, lldb::DescriptionLevel level,
ABI *abi) const {
auto *MCRegInfo = abi ? &abi->GetMCRegisterInfo() : nullptr;
auto GetRegName = [&MCRegInfo](uint64_t DwarfRegNum,
bool IsEH) -> llvm::StringRef {
if (!MCRegInfo)
return {};
if (std::optional<unsigned> LLVMRegNum =
MCRegInfo->getLLVMRegNum(DwarfRegNum, IsEH))
if (const char *RegName = MCRegInfo->getName(*LLVMRegNum))
return llvm::StringRef(RegName);
return {};
};
llvm::DIDumpOptions DumpOpts;
DumpOpts.GetNameForDWARFReg = GetRegName;
llvm::DWARFExpression(m_data.GetAsLLVM(), m_data.GetAddressByteSize())
.print(s->AsRawOstream(), DumpOpts, nullptr);
}
RegisterKind DWARFExpression::GetRegisterKind() const { return m_reg_kind; }
void DWARFExpression::SetRegisterKind(RegisterKind reg_kind) {
m_reg_kind = reg_kind;
}
static llvm::Error ReadRegisterValueAsScalar(RegisterContext *reg_ctx,
lldb::RegisterKind reg_kind,
uint32_t reg_num, Value &value) {
if (reg_ctx == nullptr)
return llvm::createStringError("no register context in frame");
const uint32_t native_reg =
reg_ctx->ConvertRegisterKindToRegisterNumber(reg_kind, reg_num);
if (native_reg == LLDB_INVALID_REGNUM)
return llvm::createStringError(
"unable to convert register kind=%u reg_num=%u to a native "
"register number",
reg_kind, reg_num);
const RegisterInfo *reg_info = reg_ctx->GetRegisterInfoAtIndex(native_reg);
RegisterValue reg_value;
if (reg_ctx->ReadRegister(reg_info, reg_value)) {
if (reg_value.GetScalarValue(value.GetScalar())) {
value.SetValueType(Value::ValueType::Scalar);
value.SetContext(Value::ContextType::RegisterInfo,
const_cast<RegisterInfo *>(reg_info));
return llvm::Error::success();
}
// If we get this error, then we need to implement a value buffer in
// the dwarf expression evaluation function...
return llvm::createStringError(
"register %s can't be converted to a scalar value", reg_info->name);
}
return llvm::createStringError("register %s is not available",
reg_info->name);
}
/// Return the length in bytes of the set of operands for \p op. No guarantees
/// are made on the state of \p data after this call.
static lldb::offset_t GetOpcodeDataSize(const DataExtractor &data,
const lldb::offset_t data_offset,
const uint8_t op,
const DWARFUnit *dwarf_cu) {
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:
if (!dwarf_cu) {
return LLDB_INVALID_OFFSET;
}
return dwarf_cu->GetSymbolFileDWARF().GetVendorDWARFOpcodeSize(
data, data_offset, op);
}
}
lldb::addr_t DWARFExpression::GetLocation_DW_OP_addr(const DWARFUnit *dwarf_cu,
bool &error) const {
error = false;
lldb::offset_t offset = 0;
while (m_data.ValidOffset(offset)) {
const uint8_t op = m_data.GetU8(&offset);
if (op == DW_OP_addr)
return m_data.GetAddress(&offset);
if (op == DW_OP_GNU_addr_index || op == DW_OP_addrx) {
uint64_t index = m_data.GetULEB128(&offset);
if (dwarf_cu)
return dwarf_cu->ReadAddressFromDebugAddrSection(index);
error = true;
break;
}
const lldb::offset_t op_arg_size =
GetOpcodeDataSize(m_data, offset, op, dwarf_cu);
if (op_arg_size == LLDB_INVALID_OFFSET) {
error = true;
break;
}
offset += op_arg_size;
}
return LLDB_INVALID_ADDRESS;
}
bool DWARFExpression::Update_DW_OP_addr(const DWARFUnit *dwarf_cu,
lldb::addr_t file_addr) {
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;
}
if (op == DW_OP_addrx) {
// Replace DW_OP_addrx with DW_OP_addr, since we can't modify the
// read-only debug_addr table.
// Subtract one to account for the opcode.
llvm::ArrayRef data_before_op = m_data.GetData().take_front(offset - 1);
// Read the addrx index to determine how many bytes it needs.
const lldb::offset_t old_offset = offset;
m_data.GetULEB128(&offset);
if (old_offset == offset)
return false;
llvm::ArrayRef data_after_op = m_data.GetData().drop_front(offset);
DataEncoder encoder(m_data.GetByteOrder(), m_data.GetAddressByteSize());
encoder.AppendData(data_before_op);
encoder.AppendU8(DW_OP_addr);
encoder.AppendAddress(file_addr);
encoder.AppendData(data_after_op);
m_data.SetData(encoder.GetDataBuffer());
return true;
}
const lldb::offset_t op_arg_size =
GetOpcodeDataSize(m_data, offset, op, dwarf_cu);
if (op_arg_size == LLDB_INVALID_OFFSET)
break;
offset += op_arg_size;
}
return false;
}
bool DWARFExpression::ContainsThreadLocalStorage(
const DWARFUnit *dwarf_cu) const {
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 lldb::offset_t op_arg_size =
GetOpcodeDataSize(m_data, offset, op, dwarf_cu);
if (op_arg_size == LLDB_INVALID_OFFSET)
return false;
offset += op_arg_size;
}
return false;
}
bool DWARFExpression::LinkThreadLocalStorage(
const DWARFUnit *dwarf_cu,
std::function<lldb::addr_t(lldb::addr_t file_addr)> const
&link_address_callback) {
const uint32_t addr_byte_size = m_data.GetAddressByteSize();
// We have to make a copy of the data as we don't know if this data is from a
// read only memory mapped buffer, so we duplicate all of the data first,
// then modify it, and if all goes well, we then replace the data for this
// expression.
// Make en encoder that contains a copy of the location expression data so we
// can write the address into the buffer using the correct byte order.
DataEncoder encoder(m_data.GetDataStart(), m_data.GetByteSize(),
m_data.GetByteOrder(), addr_byte_size);
lldb::offset_t offset = 0;
lldb::offset_t const_offset = 0;
lldb::addr_t const_value = 0;
size_t const_byte_size = 0;
while (m_data.ValidOffset(offset)) {
const 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 accordingly. For
// Darwin, the value in the DW_OP_const4u or DW_OP_const8u is the file
// address of a structure that contains a function pointer, the pthread
// key and the offset into the data pointed to by the pthread key. So we
// must link this address and also set the module of this expression to
// the new_module_sp so we can resolve the file address correctly
if (const_byte_size > 0) {
lldb::addr_t linked_file_addr = link_address_callback(const_value);
if (linked_file_addr == LLDB_INVALID_ADDRESS)
return false;
// Replace the address in the new buffer
if (encoder.PutUnsigned(const_offset, const_byte_size,
linked_file_addr) == UINT32_MAX)
return false;
}
break;
default:
const_offset = 0;
const_value = 0;
const_byte_size = 0;
break;
}
if (!decoded_data) {
const lldb::offset_t op_arg_size =
GetOpcodeDataSize(m_data, offset, op, dwarf_cu);
if (op_arg_size == LLDB_INVALID_OFFSET)
return false;
else
offset += op_arg_size;
}
}
m_data.SetData(encoder.GetDataBuffer());
return true;
}
static llvm::Error Evaluate_DW_OP_entry_value(std::vector<Value> &stack,
ExecutionContext *exe_ctx,
RegisterContext *reg_ctx,
const DataExtractor &opcodes,
lldb::offset_t &opcode_offset,
Log *log) {
// DW_OP_entry_value(sub-expr) describes the location a variable had upon
// function entry: this variable location is presumed to be optimized out at
// the current PC value. The caller of the function may have call site
// information that describes an alternate location for the variable (e.g. a
// constant literal, or a spilled stack value) in the parent frame.
//
// Example (this is pseudo-code & pseudo-DWARF, but hopefully illustrative):
//
// void child(int &sink, int x) {
// ...
// /* "x" gets optimized out. */
//
// /* The location of "x" here is: DW_OP_entry_value($reg2). */
// ++sink;
// }
//
// void parent() {
// int sink;
//
// /*
// * The callsite information emitted here is:
// *
// * DW_TAG_call_site
// * DW_AT_return_pc ... (for "child(sink, 123);")
// * DW_TAG_call_site_parameter (for "sink")
// * DW_AT_location ($reg1)
// * DW_AT_call_value ($SP - 8)
// * DW_TAG_call_site_parameter (for "x")
// * DW_AT_location ($reg2)
// * DW_AT_call_value ($literal 123)
// *
// * DW_TAG_call_site
// * DW_AT_return_pc ... (for "child(sink, 456);")
// * ...
// */
// child(sink, 123);
// child(sink, 456);
// }
//
// When the program stops at "++sink" within `child`, the debugger determines
// the call site by analyzing the return address. Once the call site is found,
// the debugger determines which parameter is referenced by DW_OP_entry_value
// and evaluates the corresponding location for that parameter in `parent`.
// 1. Find the function which pushed the current frame onto the stack.
if ((!exe_ctx || !exe_ctx->HasTargetScope()) || !reg_ctx) {
return llvm::createStringError("no exe/reg context");
}
StackFrame *current_frame = exe_ctx->GetFramePtr();
Thread *thread = exe_ctx->GetThreadPtr();
if (!current_frame || !thread)
return llvm::createStringError("no current frame/thread");
Target &target = exe_ctx->GetTargetRef();
StackFrameSP parent_frame = nullptr;
addr_t return_pc = LLDB_INVALID_ADDRESS;
uint32_t current_frame_idx = current_frame->GetFrameIndex();
for (uint32_t parent_frame_idx = current_frame_idx + 1;;parent_frame_idx++) {
parent_frame = thread->GetStackFrameAtIndex(parent_frame_idx);
// If this is null, we're at the end of the stack.
if (!parent_frame)
break;
// Record the first valid return address, even if this is an inlined frame,
// in order to look up the associated call edge in the first non-inlined
// parent frame.
if (return_pc == LLDB_INVALID_ADDRESS) {
return_pc = parent_frame->GetFrameCodeAddress().GetLoadAddress(&target);
LLDB_LOG(log, "immediate ancestor with pc = {0:x}", return_pc);
}
// If we've found an inlined frame, skip it (these have no call site
// parameters).
if (parent_frame->IsInlined())
continue;
// We've found the first non-inlined parent frame.
break;
}
if (!parent_frame || !parent_frame->GetRegisterContext()) {
return llvm::createStringError("no parent frame with reg ctx");
}
Function *parent_func =
parent_frame->GetSymbolContext(eSymbolContextFunction).function;
if (!parent_func)
return llvm::createStringError("no parent function");
// 2. Find the call edge in the parent function responsible for creating the
// current activation.
Function *current_func =
current_frame->GetSymbolContext(eSymbolContextFunction).function;
if (!current_func)
return llvm::createStringError("no current function");
CallEdge *call_edge = nullptr;
ModuleList &modlist = target.GetImages();
ExecutionContext parent_exe_ctx = *exe_ctx;
parent_exe_ctx.SetFrameSP(parent_frame);
if (!parent_frame->IsArtificial()) {
// If the parent frame is not artificial, the current activation may be
// produced by an ambiguous tail call. In this case, refuse to proceed.
call_edge = parent_func->GetCallEdgeForReturnAddress(return_pc, target);
if (!call_edge) {
return llvm::createStringError(
llvm::formatv("no call edge for retn-pc = {0:x} in parent frame {1}",
return_pc, parent_func->GetName()));
}
Function *callee_func = call_edge->GetCallee(modlist, parent_exe_ctx);
if (callee_func != current_func) {
return llvm::createStringError(
"ambiguous call sequence, can't find real parent frame");
}
} else {
// The StackFrameList solver machinery has deduced that an unambiguous tail
// call sequence that produced the current activation. The first edge in
// the parent that points to the current function must be valid.
for (auto &edge : parent_func->GetTailCallingEdges()) {
if (edge->GetCallee(modlist, parent_exe_ctx) == current_func) {
call_edge = edge.get();
break;
}
}
}
if (!call_edge)
return llvm::createStringError("no unambiguous edge from parent "
"to current function");
// 3. Attempt to locate the DW_OP_entry_value expression in the set of
// available call site parameters. If found, evaluate the corresponding
// parameter in the context of the parent frame.
const uint32_t subexpr_len = opcodes.GetULEB128(&opcode_offset);
const void *subexpr_data = opcodes.GetData(&opcode_offset, subexpr_len);
if (!subexpr_data)
return llvm::createStringError("subexpr could not be read");
const CallSiteParameter *matched_param = nullptr;
for (const CallSiteParameter &param : call_edge->GetCallSiteParameters()) {
DataExtractor param_subexpr_extractor;
if (!param.LocationInCallee.GetExpressionData(param_subexpr_extractor))
continue;
lldb::offset_t param_subexpr_offset = 0;
const void *param_subexpr_data =
param_subexpr_extractor.GetData(&param_subexpr_offset, subexpr_len);
if (!param_subexpr_data ||
param_subexpr_extractor.BytesLeft(param_subexpr_offset) != 0)
continue;
// At this point, the DW_OP_entry_value sub-expression and the callee-side
// expression in the call site parameter are known to have the same length.
// Check whether they are equal.
//
// Note that an equality check is sufficient: the contents of the
// DW_OP_entry_value subexpression are only used to identify the right call
// site parameter in the parent, and do not require any special handling.
if (memcmp(subexpr_data, param_subexpr_data, subexpr_len) == 0) {
matched_param = &param;
break;
}
}
if (!matched_param)
return llvm::createStringError("no matching call site param found");
// TODO: Add support for DW_OP_push_object_address within a DW_OP_entry_value
// subexpresion whenever llvm does.
const DWARFExpressionList &param_expr = matched_param->LocationInCaller;
llvm::Expected<Value> maybe_result = param_expr.Evaluate(
&parent_exe_ctx, parent_frame->GetRegisterContext().get(),
LLDB_INVALID_ADDRESS,
/*initial_value_ptr=*/nullptr,
/*object_address_ptr=*/nullptr);
if (!maybe_result) {
LLDB_LOG(log,
"Evaluate_DW_OP_entry_value: call site param evaluation failed");
return maybe_result.takeError();
}
stack.push_back(*maybe_result);
return llvm::Error::success();
}
namespace {
/// The location description kinds described by the DWARF v5
/// specification. Composite locations are handled out-of-band and
/// thus aren't part of the enum.
enum LocationDescriptionKind {
Empty,
Memory,
Register,
Implicit
/* Composite*/
};
/// Adjust value's ValueType according to the kind of location description.
void UpdateValueTypeFromLocationDescription(Log *log, const 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 DWARFExpression::Eval() that deals with DWARF
// location descriptions (which consist of one or more DWARF
// expressions). But doing this would mean we'd also need factor the
// handling of DW_OP_(bit_)piece out of this function.
if (dwarf_cu && dwarf_cu->GetVersion() >= 4) {
const char *log_msg = "DWARF location description kind: %s";
switch (kind) {
case Empty:
LLDB_LOGF(log, log_msg, "Empty");
break;
case Memory:
LLDB_LOGF(log, log_msg, "Memory");
if (value->GetValueType() == Value::ValueType::Scalar)
value->SetValueType(Value::ValueType::LoadAddress);
break;
case Register:
LLDB_LOGF(log, log_msg, "Register");
value->SetValueType(Value::ValueType::Scalar);
break;
case Implicit:
LLDB_LOGF(log, log_msg, "Implicit");
if (value->GetValueType() == Value::ValueType::LoadAddress)
value->SetValueType(Value::ValueType::Scalar);
break;
}
}
}
} // namespace
/// Helper function to move common code used to resolve a file address and turn
/// into a load address.
///
/// \param exe_ctx Pointer to the execution context
/// \param module_sp shared_ptr contains the module if we have one
/// \param dw_op_type C-style string used to vary the error output
/// \param file_addr the file address we are trying to resolve and turn into a
/// load address
/// \param so_addr out parameter, will be set to load address or section offset
/// \param check_sectionoffset bool which determines if having a section offset
/// but not a load address is considerd a success
/// \returns std::optional containing the load address if resolving and getting
/// the load address succeed or an empty Optinal otherwise. If
/// check_sectionoffset is true we consider LLDB_INVALID_ADDRESS a
/// success if so_addr.IsSectionOffset() is true.
static llvm::Expected<lldb::addr_t>
ResolveLoadAddress(ExecutionContext *exe_ctx, lldb::ModuleSP &module_sp,
const char *dw_op_type, lldb::addr_t file_addr,
Address &so_addr, bool check_sectionoffset = false) {
if (!module_sp)
return llvm::createStringError("need module to resolve file address for %s",
dw_op_type);
if (!module_sp->ResolveFileAddress(file_addr, so_addr))
return llvm::createStringError("failed to resolve file address in module");
const addr_t load_addr = so_addr.GetLoadAddress(exe_ctx->GetTargetPtr());
if (load_addr == LLDB_INVALID_ADDRESS &&
(check_sectionoffset && !so_addr.IsSectionOffset()))
return llvm::createStringError("failed to resolve load address");
return load_addr;
}
/// Helper function to move common code used to load sized data from a uint8_t
/// buffer.
///
/// \param addr_bytes uint8_t buffer containg raw data
/// \param size_addr_bytes how large is the underlying raw data
/// \param byte_order what is the byter order of the underlyig data
/// \param size How much of the underlying data we want to use
/// \return The underlying data converted into a Scalar
static Scalar DerefSizeExtractDataHelper(uint8_t *addr_bytes,
size_t size_addr_bytes,
ByteOrder byte_order, size_t size) {
DataExtractor addr_data(addr_bytes, size_addr_bytes, byte_order, size);
lldb::offset_t addr_data_offset = 0;
if (size <= 8)
return addr_data.GetMaxU64(&addr_data_offset, size);
else
return addr_data.GetAddress(&addr_data_offset);
}
llvm::Expected<Value> DWARFExpression::Evaluate(
ExecutionContext *exe_ctx, RegisterContext *reg_ctx,
lldb::ModuleSP module_sp, const DataExtractor &opcodes,
const DWARFUnit *dwarf_cu, const lldb::RegisterKind reg_kind,
const Value *initial_value_ptr, const Value *object_address_ptr) {
if (opcodes.GetByteSize() == 0)
return llvm::createStringError(
"no location, value may have been optimized out");
std::vector<Value> stack;
Process *process = nullptr;
StackFrame *frame = nullptr;
Target *target = nullptr;
if (exe_ctx) {
process = exe_ctx->GetProcessPtr();
frame = exe_ctx->GetFramePtr();
target = exe_ctx->GetTargetPtr();
}
if (reg_ctx == nullptr && frame)
reg_ctx = frame->GetRegisterContext().get();
if (initial_value_ptr)
stack.push_back(*initial_value_ptr);
lldb::offset_t offset = 0;
Value tmp;
uint32_t reg_num;
/// Insertion point for evaluating multi-piece expression.
uint64_t op_piece_offset = 0;
Value pieces; // Used for DW_OP_piece
Log *log = GetLog(LLDBLog::Expressions);
// A generic type is "an integral type that has the size of an address and an
// unspecified signedness". For now, just use the signedness of the operand.
// TODO: Implement a real typed stack, and store the genericness of the value
// there.
auto to_generic = [&](auto v) {
// TODO: Avoid implicit trunc?
// See https://github.com/llvm/llvm-project/issues/112510.
bool is_signed = std::is_signed<decltype(v)>::value;
return Scalar(llvm::APSInt(llvm::APInt(8 * opcodes.GetAddressByteSize(), v,
is_signed, /*implicitTrunc=*/true),
!is_signed));
};
// The default kind is a memory location. This is updated by any
// operation that changes this, such as DW_OP_stack_value, and reset
// by composition operations like DW_OP_piece.
LocationDescriptionKind dwarf4_location_description_kind = Memory;
while (opcodes.ValidOffset(offset)) {
const lldb::offset_t op_offset = offset;
const uint8_t op = opcodes.GetU8(&offset);
if (log && log->GetVerbose()) {
size_t count = stack.size();
LLDB_LOGF(log, "Stack before operation has %" PRIu64 " values:",
(uint64_t)count);
for (size_t i = 0; i < count; ++i) {
StreamString new_value;
new_value.Printf("[%" PRIu64 "]", (uint64_t)i);
stack[i].Dump(&new_value);
LLDB_LOGF(log, " %s", new_value.GetData());
}
LLDB_LOGF(log, "0x%8.8" PRIx64 ": %s", op_offset,
DW_OP_value_to_name(op));
}
if (std::optional<unsigned> arity =
llvm::dwarf::OperationArity(static_cast<LocationAtom>(op))) {
if (stack.size() < *arity)
return llvm::createStringError(
"%s needs at least %d stack entries (stack has %d entries)",
DW_OP_value_to_name(op), *arity, stack.size());
}
switch (op) {
// The DW_OP_addr operation has a single operand that encodes a machine
// address and whose size is the size of an address on the target machine.
case DW_OP_addr:
stack.push_back(Scalar(opcodes.GetAddress(&offset)));
if (target &&
target->GetArchitecture().GetCore() == ArchSpec::eCore_wasm32) {
// wasm file sections aren't mapped into memory, therefore addresses can
// never point into a file section and are always LoadAddresses.
stack.back().SetValueType(Value::ValueType::LoadAddress);
} else {
stack.back().SetValueType(Value::ValueType::FileAddress);
}
break;
// The DW_OP_addr_sect_offset4 is used for any location expressions in
// shared libraries that have a location like:
// DW_OP_addr(0x1000)
// If this address resides in a shared library, then this virtual address
// won't make sense when it is evaluated in the context of a running
// process where shared libraries have been slid. To account for this, this
// new address type where we can store the section pointer and a 4 byte
// offset.
// case DW_OP_addr_sect_offset4:
// {
// result_type = eResultTypeFileAddress;
// lldb::Section *sect = (lldb::Section
// *)opcodes.GetMaxU64(&offset, sizeof(void *));
// lldb::addr_t sect_offset = opcodes.GetU32(&offset);
//
// Address so_addr (sect, sect_offset);
// lldb::addr_t load_addr = so_addr.GetLoadAddress();
// if (load_addr != LLDB_INVALID_ADDRESS)
// {
// // We successfully resolve a file address to a load
// // address.
// stack.push_back(load_addr);
// break;
// }
// else
// {
// // We were able
// if (error_ptr)
// error_ptr->SetErrorStringWithFormat ("Section %s in
// %s is not currently loaded.\n",
// sect->GetName().AsCString(),
// sect->GetModule()->GetFileSpec().GetFilename().AsCString());
// return false;
// }
// }
// break;
// OPCODE: DW_OP_deref
// OPERANDS: none
// DESCRIPTION: Pops the top stack entry and treats it as an address.
// The value retrieved from that address is pushed. The size of the data
// retrieved from the dereferenced address is the size of an address on the
// target machine.
case DW_OP_deref: {
if (stack.empty())
return llvm::createStringError(
"expression stack empty for DW_OP_deref");
Value::ValueType value_type = stack.back().GetValueType();
switch (value_type) {
case Value::ValueType::HostAddress: {
void *src = (void *)stack.back().GetScalar().ULongLong();
intptr_t ptr;
::memcpy(&ptr, src, sizeof(void *));
stack.back().GetScalar() = ptr;
stack.back().ClearContext();
} break;
case Value::ValueType::FileAddress: {
auto file_addr = stack.back().GetScalar().ULongLong(
LLDB_INVALID_ADDRESS);
Address so_addr;
auto maybe_load_addr = ResolveLoadAddress(
exe_ctx, module_sp, "DW_OP_deref", file_addr, so_addr);
if (!maybe_load_addr)
return maybe_load_addr.takeError();
stack.back().GetScalar() = *maybe_load_addr;
// Fall through to load address promotion code below.
}
[[fallthrough]];
case Value::ValueType::Scalar:
// Promote Scalar to LoadAddress and fall through.
stack.back().SetValueType(Value::ValueType::LoadAddress);
[[fallthrough]];
case Value::ValueType::LoadAddress:
if (exe_ctx) {
if (process) {
lldb::addr_t pointer_addr =
stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
Status error;
lldb::addr_t pointer_value =
process->ReadPointerFromMemory(pointer_addr, error);
if (pointer_value != LLDB_INVALID_ADDRESS) {
if (ABISP abi_sp = process->GetABI())
pointer_value = abi_sp->FixCodeAddress(pointer_value);
stack.back().GetScalar() = pointer_value;
stack.back().ClearContext();
} else {
return llvm::createStringError(
"Failed to dereference pointer from 0x%" PRIx64
" for DW_OP_deref: %s\n",
pointer_addr, error.AsCString());
}
} else {
return llvm::createStringError("NULL process for DW_OP_deref");
}
} else {
return llvm::createStringError(
"NULL execution context for DW_OP_deref");
}
break;
case Value::ValueType::Invalid:
return llvm::createStringError("invalid value type for DW_OP_deref");
}
} break;
// OPCODE: DW_OP_deref_size
// OPERANDS: 1
// 1 - uint8_t that specifies the size of the data to dereference.
// DESCRIPTION: Behaves like the DW_OP_deref operation: it pops the top
// stack entry and treats it as an address. The value retrieved from that
// address is pushed. In the DW_OP_deref_size operation, however, the size
// in bytes of the data retrieved from the dereferenced address is
// specified by the single operand. This operand is a 1-byte unsigned
// integral constant whose value may not be larger than the size of an
// address on the target machine. The data retrieved is zero extended to
// the size of an address on the target machine before being pushed on the
// expression stack.
case DW_OP_deref_size: {
if (stack.empty()) {
return llvm::createStringError(
"expression stack empty for DW_OP_deref_size");
}
uint8_t size = opcodes.GetU8(&offset);
if (size > 8) {
return llvm::createStringError(
"Invalid address size for DW_OP_deref_size: %d\n", size);
}
Value::ValueType value_type = stack.back().GetValueType();
switch (value_type) {
case Value::ValueType::HostAddress: {
void *src = (void *)stack.back().GetScalar().ULongLong();
intptr_t ptr;
::memcpy(&ptr, src, sizeof(void *));
// I can't decide whether the size operand should apply to the bytes in
// their
// lldb-host endianness or the target endianness.. I doubt this'll ever
// come up but I'll opt for assuming big endian regardless.
switch (size) {
case 1:
ptr = ptr & 0xff;
break;
case 2:
ptr = ptr & 0xffff;
break;
case 3:
ptr = ptr & 0xffffff;
break;
case 4:
ptr = ptr & 0xffffffff;
break;
// the casts are added to work around the case where intptr_t is a 32
// bit quantity;
// presumably we won't hit the 5..7 cases if (void*) is 32-bits in this
// program.
case 5:
ptr = (intptr_t)ptr & 0xffffffffffULL;
break;
case 6:
ptr = (intptr_t)ptr & 0xffffffffffffULL;
break;
case 7:
ptr = (intptr_t)ptr & 0xffffffffffffffULL;
break;
default:
break;
}
stack.back().GetScalar() = ptr;
stack.back().ClearContext();
} break;
case Value::ValueType::FileAddress: {
auto file_addr =
stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
Address so_addr;
auto maybe_load_addr = ResolveLoadAddress(
exe_ctx, module_sp, "DW_OP_deref_size", file_addr, so_addr,
/*check_sectionoffset=*/true);
if (!maybe_load_addr)
return maybe_load_addr.takeError();
addr_t load_addr = *maybe_load_addr;
if (load_addr == LLDB_INVALID_ADDRESS && so_addr.IsSectionOffset()) {
uint8_t addr_bytes[8];
Status error;
if (target &&
target->ReadMemory(so_addr, &addr_bytes, size, error,
/*force_live_memory=*/false) == size) {
ObjectFile *objfile = module_sp->GetObjectFile();
stack.back().GetScalar() = DerefSizeExtractDataHelper(
addr_bytes, size, objfile->GetByteOrder(), size);
stack.back().ClearContext();
break;
} else {
return llvm::createStringError(
"Failed to dereference pointer for DW_OP_deref_size: "
"%s\n",
error.AsCString());
}
}
stack.back().GetScalar() = load_addr;
// Fall through to load address promotion code below.
}
[[fallthrough]];
case Value::ValueType::Scalar:
case Value::ValueType::LoadAddress:
if (exe_ctx) {
if (process) {
lldb::addr_t pointer_addr =
stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
uint8_t addr_bytes[sizeof(lldb::addr_t)];
Status error;
if (process->ReadMemory(pointer_addr, &addr_bytes, size, error) ==
size) {
stack.back().GetScalar() =
DerefSizeExtractDataHelper(addr_bytes, sizeof(addr_bytes),
process->GetByteOrder(), size);
stack.back().ClearContext();
} else {
return llvm::createStringError(
"Failed to dereference pointer from 0x%" PRIx64
" for DW_OP_deref: %s\n",
pointer_addr, error.AsCString());
}
} else {
return llvm::createStringError("NULL process for DW_OP_deref_size");
}
} else {
return llvm::createStringError(
"NULL execution context for DW_OP_deref_size");
}
break;
case Value::ValueType::Invalid:
return llvm::createStringError("invalid value for DW_OP_deref_size");
}
} break;
// OPCODE: DW_OP_xderef_size
// OPERANDS: 1
// 1 - uint8_t that specifies the size of the data to dereference.
// DESCRIPTION: Behaves like the DW_OP_xderef operation: the entry at
// the top of the stack is treated as an address. The second stack entry is
// treated as an "address space identifier" for those architectures that
// support multiple address spaces. The top two stack elements are popped,
// a data item is retrieved through an implementation-defined address
// calculation and pushed as the new stack top. In the DW_OP_xderef_size
// operation, however, the size in bytes of the data retrieved from the
// dereferenced address is specified by the single operand. This operand is
// a 1-byte unsigned integral constant whose value may not be larger than
// the size of an address on the target machine. The data retrieved is zero
// extended to the size of an address on the target machine before being
// pushed on the expression stack.
case DW_OP_xderef_size:
return llvm::createStringError("unimplemented opcode: DW_OP_xderef_size");
// OPCODE: DW_OP_xderef
// OPERANDS: none
// DESCRIPTION: Provides an extended dereference mechanism. The entry at
// the top of the stack is treated as an address. The second stack entry is
// treated as an "address space identifier" for those architectures that
// support multiple address spaces. The top two stack elements are popped,
// a data item is retrieved through an implementation-defined address
// calculation and pushed as the new stack top. The size of the data
// retrieved from the dereferenced address is the size of an address on the
// target machine.
case DW_OP_xderef:
return llvm::createStringError("unimplemented opcode: DW_OP_xderef");
// All DW_OP_constXXX opcodes have a single operand as noted below:
//
// Opcode Operand 1
// DW_OP_const1u 1-byte unsigned integer constant
// DW_OP_const1s 1-byte signed integer constant
// DW_OP_const2u 2-byte unsigned integer constant
// DW_OP_const2s 2-byte signed integer constant
// DW_OP_const4u 4-byte unsigned integer constant
// DW_OP_const4s 4-byte signed integer constant
// DW_OP_const8u 8-byte unsigned integer constant
// DW_OP_const8s 8-byte signed integer constant
// DW_OP_constu unsigned LEB128 integer constant
// DW_OP_consts signed LEB128 integer constant
case DW_OP_const1u:
stack.push_back(to_generic(opcodes.GetU8(&offset)));
break;
case DW_OP_const1s:
stack.push_back(to_generic((int8_t)opcodes.GetU8(&offset)));
break;
case DW_OP_const2u:
stack.push_back(to_generic(opcodes.GetU16(&offset)));
break;
case DW_OP_const2s:
stack.push_back(to_generic((int16_t)opcodes.GetU16(&offset)));
break;
case DW_OP_const4u:
stack.push_back(to_generic(opcodes.GetU32(&offset)));
break;
case DW_OP_const4s:
stack.push_back(to_generic((int32_t)opcodes.GetU32(&offset)));
break;
case DW_OP_const8u:
stack.push_back(to_generic(opcodes.GetU64(&offset)));
break;
case DW_OP_const8s:
stack.push_back(to_generic((int64_t)opcodes.GetU64(&offset)));
break;
// These should also use to_generic, but we can't do that due to a
// producer-side bug in llvm. See llvm.org/pr48087.
case DW_OP_constu:
stack.push_back(Scalar(opcodes.GetULEB128(&offset)));
break;
case DW_OP_consts:
stack.push_back(Scalar(opcodes.GetSLEB128(&offset)));
break;
// OPCODE: DW_OP_dup
// OPERANDS: none
// DESCRIPTION: duplicates the value at the top of the stack
case DW_OP_dup:
if (stack.empty()) {
return llvm::createStringError("expression stack empty for DW_OP_dup");
} else
stack.push_back(stack.back());
break;
// OPCODE: DW_OP_drop
// OPERANDS: none
// DESCRIPTION: pops the value at the top of the stack
case DW_OP_drop:
if (stack.empty()) {
return llvm::createStringError("expression stack empty for DW_OP_drop");
} else
stack.pop_back();
break;
// OPCODE: DW_OP_over
// OPERANDS: none
// DESCRIPTION: Duplicates the entry currently second in the stack at
// the top of the stack.
case DW_OP_over:
stack.push_back(stack[stack.size() - 2]);
break;
// OPCODE: DW_OP_pick
// OPERANDS: uint8_t index into the current stack
// DESCRIPTION: The stack entry with the specified index (0 through 255,
// inclusive) is pushed on the stack
case DW_OP_pick: {
uint8_t pick_idx = opcodes.GetU8(&offset);
if (pick_idx < stack.size())
stack.push_back(stack[stack.size() - 1 - pick_idx]);
else {
return llvm::createStringError(
"Index %u out of range for DW_OP_pick.\n", pick_idx);
}
} break;
// OPCODE: DW_OP_swap
// OPERANDS: none
// DESCRIPTION: swaps the top two stack entries. The entry at the top
// of the stack becomes the second stack entry, and the second entry
// becomes the top of the stack
case DW_OP_swap:
tmp = stack.back();
stack.back() = stack[stack.size() - 2];
stack[stack.size() - 2] = tmp;
break;
// OPCODE: DW_OP_rot
// OPERANDS: none
// DESCRIPTION: Rotates the first three stack entries. The entry at
// the top of the stack becomes the third stack entry, the second entry
// becomes the top of the stack, and the third entry becomes the second
// entry.
case DW_OP_rot: {
size_t last_idx = stack.size() - 1;
Value old_top = stack[last_idx];
stack[last_idx] = stack[last_idx - 1];
stack[last_idx - 1] = stack[last_idx - 2];
stack[last_idx - 2] = old_top;
} break;
// OPCODE: DW_OP_abs
// OPERANDS: none
// DESCRIPTION: pops the top stack entry, interprets it as a signed
// value and pushes its absolute value. If the absolute value can not be
// represented, the result is undefined.
case DW_OP_abs:
if (!stack.back().ResolveValue(exe_ctx).AbsoluteValue()) {
return llvm::createStringError(
"failed to take the absolute value of the first stack item");
}
break;
// OPCODE: DW_OP_and
// OPERANDS: none
// DESCRIPTION: pops the top two stack values, performs a bitwise and
// operation on the two, and pushes the result.
case DW_OP_and:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) & tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_div
// OPERANDS: none
// DESCRIPTION: pops the top two stack values, divides the former second
// entry by the former top of the stack using signed division, and pushes
// the result.
case DW_OP_div: {
tmp = stack.back();
if (tmp.ResolveValue(exe_ctx).IsZero())
return llvm::createStringError("divide by zero");
stack.pop_back();
Scalar divisor, dividend;
divisor = tmp.ResolveValue(exe_ctx);
dividend = stack.back().ResolveValue(exe_ctx);
divisor.MakeSigned();
dividend.MakeSigned();
stack.back() = dividend / divisor;
if (!stack.back().ResolveValue(exe_ctx).IsValid())
return llvm::createStringError("divide failed");
} break;
// OPCODE: DW_OP_minus
// OPERANDS: none
// DESCRIPTION: pops the top two stack values, subtracts the former top
// of the stack from the former second entry, and pushes the result.
case DW_OP_minus:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) - tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_mod
// OPERANDS: none
// DESCRIPTION: pops the top two stack values and pushes the result of
// the calculation: former second stack entry modulo the former top of the
// stack.
case DW_OP_mod:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) % tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_mul
// OPERANDS: none
// DESCRIPTION: pops the top two stack entries, multiplies them
// together, and pushes the result.
case DW_OP_mul:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) * tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_neg
// OPERANDS: none
// DESCRIPTION: pops the top stack entry, and pushes its negation.
case DW_OP_neg:
if (!stack.back().ResolveValue(exe_ctx).UnaryNegate())
return llvm::createStringError("unary negate failed");
break;
// OPCODE: DW_OP_not
// OPERANDS: none
// DESCRIPTION: pops the top stack entry, and pushes its bitwise
// complement
case DW_OP_not:
if (!stack.back().ResolveValue(exe_ctx).OnesComplement())
return llvm::createStringError("logical NOT failed");
break;
// OPCODE: DW_OP_or
// OPERANDS: none
// DESCRIPTION: pops the top two stack entries, performs a bitwise or
// operation on the two, and pushes the result.
case DW_OP_or:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) | tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_plus
// OPERANDS: none
// DESCRIPTION: pops the top two stack entries, adds them together, and
// pushes the result.
case DW_OP_plus:
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() += tmp.GetScalar();
break;
// OPCODE: DW_OP_plus_uconst
// OPERANDS: none
// DESCRIPTION: pops the top stack entry, adds it to the unsigned LEB128
// constant operand and pushes the result.
case DW_OP_plus_uconst: {
const uint64_t uconst_value = opcodes.GetULEB128(&offset);
// Implicit conversion from a UINT to a Scalar...
stack.back().GetScalar() += uconst_value;
if (!stack.back().GetScalar().IsValid())
return llvm::createStringError("DW_OP_plus_uconst failed");
} break;
// OPCODE: DW_OP_shl
// OPERANDS: none
// DESCRIPTION: pops the top two stack entries, shifts the former
// second entry left by the number of bits specified by the former top of
// the stack, and pushes the result.
case DW_OP_shl:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) <<= tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_shr
// OPERANDS: none
// DESCRIPTION: pops the top two stack entries, shifts the former second
// entry right logically (filling with zero bits) by the number of bits
// specified by the former top of the stack, and pushes the result.
case DW_OP_shr:
tmp = stack.back();
stack.pop_back();
if (!stack.back().ResolveValue(exe_ctx).ShiftRightLogical(
tmp.ResolveValue(exe_ctx)))
return llvm::createStringError("DW_OP_shr failed");
break;
// OPCODE: DW_OP_shra
// OPERANDS: none
// DESCRIPTION: pops the top two stack entries, shifts the former second
// entry right arithmetically (divide the magnitude by 2, keep the same
// sign for the result) by the number of bits specified by the former top
// of the stack, and pushes the result.
case DW_OP_shra:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) >>= tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_xor
// OPERANDS: none
// DESCRIPTION: pops the top two stack entries, performs the bitwise
// exclusive-or operation on the two, and pushes the result.
case DW_OP_xor:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) ^ tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_skip
// OPERANDS: int16_t
// DESCRIPTION: An unconditional branch. Its single operand is a 2-byte
// signed integer constant. The 2-byte constant is the number of bytes of
// the DWARF expression to skip forward or backward from the current
// operation, beginning after the 2-byte constant.
case DW_OP_skip: {
int16_t skip_offset = (int16_t)opcodes.GetU16(&offset);
lldb::offset_t new_offset = offset + skip_offset;
// New offset can point at the end of the data, in this case we should
// terminate the DWARF expression evaluation (will happen in the loop
// condition).
if (new_offset <= opcodes.GetByteSize())
offset = new_offset;
else {
return llvm::createStringError(llvm::formatv(
"Invalid opcode offset in DW_OP_skip: {0}+({1}) > {2}", offset,
skip_offset, opcodes.GetByteSize()));
}
} break;
// OPCODE: DW_OP_bra
// OPERANDS: int16_t
// DESCRIPTION: A conditional branch. Its single operand is a 2-byte
// signed integer constant. This operation pops the top of stack. If the
// value popped is not the constant 0, the 2-byte constant operand is the
// number of bytes of the DWARF expression to skip forward or backward from
// the current operation, beginning after the 2-byte constant.
case DW_OP_bra: {
tmp = stack.back();
stack.pop_back();
int16_t bra_offset = (int16_t)opcodes.GetU16(&offset);
Scalar zero(0);
if (tmp.ResolveValue(exe_ctx) != zero) {
lldb::offset_t new_offset = offset + bra_offset;
// New offset can point at the end of the data, in this case we should
// terminate the DWARF expression evaluation (will happen in the loop
// condition).
if (new_offset <= opcodes.GetByteSize())
offset = new_offset;
else {
return llvm::createStringError(llvm::formatv(
"Invalid opcode offset in DW_OP_bra: {0}+({1}) > {2}", offset,
bra_offset, opcodes.GetByteSize()));
}
}
} break;
// OPCODE: DW_OP_eq
// OPERANDS: none
// DESCRIPTION: pops the top two stack values, compares using the
// equals (==) operator.
// STACK RESULT: push the constant value 1 onto the stack if the result
// of the operation is true or the constant value 0 if the result of the
// operation is false.
case DW_OP_eq:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) == tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_ge
// OPERANDS: none
// DESCRIPTION: pops the top two stack values, compares using the
// greater than or equal to (>=) operator.
// STACK RESULT: push the constant value 1 onto the stack if the result
// of the operation is true or the constant value 0 if the result of the
// operation is false.
case DW_OP_ge:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) >= tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_gt
// OPERANDS: none
// DESCRIPTION: pops the top two stack values, compares using the
// greater than (>) operator.
// STACK RESULT: push the constant value 1 onto the stack if the result
// of the operation is true or the constant value 0 if the result of the
// operation is false.
case DW_OP_gt:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) > tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_le
// OPERANDS: none
// DESCRIPTION: pops the top two stack values, compares using the
// less than or equal to (<=) operator.
// STACK RESULT: push the constant value 1 onto the stack if the result
// of the operation is true or the constant value 0 if the result of the
// operation is false.
case DW_OP_le:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) <= tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_lt
// OPERANDS: none
// DESCRIPTION: pops the top two stack values, compares using the
// less than (<) operator.
// STACK RESULT: push the constant value 1 onto the stack if the result
// of the operation is true or the constant value 0 if the result of the
// operation is false.
case DW_OP_lt:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) < tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_ne
// OPERANDS: none
// DESCRIPTION: pops the top two stack values, compares using the
// not equal (!=) operator.
// STACK RESULT: push the constant value 1 onto the stack if the result
// of the operation is true or the constant value 0 if the result of the
// operation is false.
case DW_OP_ne:
tmp = stack.back();
stack.pop_back();
stack.back().ResolveValue(exe_ctx) =
stack.back().ResolveValue(exe_ctx) != tmp.ResolveValue(exe_ctx);
break;
// OPCODE: DW_OP_litn
// OPERANDS: none
// DESCRIPTION: encode the unsigned literal values from 0 through 31.
// STACK RESULT: push the unsigned literal constant value onto the top
// of the stack.
case DW_OP_lit0:
case DW_OP_lit1:
case DW_OP_lit2:
case DW_OP_lit3:
case DW_OP_lit4:
case DW_OP_lit5:
case DW_OP_lit6:
case DW_OP_lit7:
case DW_OP_lit8:
case DW_OP_lit9:
case DW_OP_lit10:
case DW_OP_lit11:
case DW_OP_lit12:
case DW_OP_lit13:
case DW_OP_lit14:
case DW_OP_lit15:
case DW_OP_lit16:
case DW_OP_lit17:
case DW_OP_lit18:
case DW_OP_lit19:
case DW_OP_lit20:
case DW_OP_lit21:
case DW_OP_lit22:
case DW_OP_lit23:
case DW_OP_lit24:
case DW_OP_lit25:
case DW_OP_lit26:
case DW_OP_lit27:
case DW_OP_lit28:
case DW_OP_lit29:
case DW_OP_lit30:
case DW_OP_lit31:
stack.push_back(to_generic(op - DW_OP_lit0));
break;
// OPCODE: DW_OP_regN
// OPERANDS: none
// DESCRIPTION: Push the value in register n on the top of the stack.
case DW_OP_reg0:
case DW_OP_reg1:
case DW_OP_reg2:
case DW_OP_reg3:
case DW_OP_reg4:
case DW_OP_reg5:
case DW_OP_reg6:
case DW_OP_reg7:
case DW_OP_reg8:
case DW_OP_reg9:
case DW_OP_reg10:
case DW_OP_reg11:
case DW_OP_reg12:
case DW_OP_reg13:
case DW_OP_reg14:
case DW_OP_reg15:
case DW_OP_reg16:
case DW_OP_reg17:
case DW_OP_reg18:
case DW_OP_reg19:
case DW_OP_reg20:
case DW_OP_reg21:
case DW_OP_reg22:
case DW_OP_reg23:
case DW_OP_reg24:
case DW_OP_reg25:
case DW_OP_reg26:
case DW_OP_reg27:
case DW_OP_reg28:
case DW_OP_reg29:
case DW_OP_reg30:
case DW_OP_reg31: {
dwarf4_location_description_kind = Register;
reg_num = op - DW_OP_reg0;
if (llvm::Error err =
ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, tmp))
return err;
stack.push_back(tmp);
} break;
// OPCODE: DW_OP_regx
// OPERANDS:
// ULEB128 literal operand that encodes the register.
// DESCRIPTION: Push the value in register on the top of the stack.
case DW_OP_regx: {
dwarf4_location_description_kind = Register;
reg_num = opcodes.GetULEB128(&offset);
Status read_err;
if (llvm::Error err =
ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, tmp))
return err;
stack.push_back(tmp);
} break;
// OPCODE: DW_OP_bregN
// OPERANDS:
// SLEB128 offset from register N
// DESCRIPTION: Value is in memory at the address specified by register
// N plus an offset.
case DW_OP_breg0:
case DW_OP_breg1:
case DW_OP_breg2:
case DW_OP_breg3:
case DW_OP_breg4:
case DW_OP_breg5:
case DW_OP_breg6:
case DW_OP_breg7:
case DW_OP_breg8:
case DW_OP_breg9:
case DW_OP_breg10:
case DW_OP_breg11:
case DW_OP_breg12:
case DW_OP_breg13:
case DW_OP_breg14:
case DW_OP_breg15:
case DW_OP_breg16:
case DW_OP_breg17:
case DW_OP_breg18:
case DW_OP_breg19:
case DW_OP_breg20:
case DW_OP_breg21:
case DW_OP_breg22:
case DW_OP_breg23:
case DW_OP_breg24:
case DW_OP_breg25:
case DW_OP_breg26:
case DW_OP_breg27:
case DW_OP_breg28:
case DW_OP_breg29:
case DW_OP_breg30:
case DW_OP_breg31: {
reg_num = op - DW_OP_breg0;
if (llvm::Error err =
ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, tmp))
return err;
int64_t breg_offset = opcodes.GetSLEB128(&offset);
tmp.ResolveValue(exe_ctx) += (uint64_t)breg_offset;
tmp.ClearContext();
stack.push_back(tmp);
stack.back().SetValueType(Value::ValueType::LoadAddress);
} break;
// OPCODE: DW_OP_bregx
// OPERANDS: 2
// ULEB128 literal operand that encodes the register.
// SLEB128 offset from register N
// DESCRIPTION: Value is in memory at the address specified by register
// N plus an offset.
case DW_OP_bregx: {
reg_num = opcodes.GetULEB128(&offset);
if (llvm::Error err =
ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, tmp))
return err;
int64_t breg_offset = opcodes.GetSLEB128(&offset);
tmp.ResolveValue(exe_ctx) += (uint64_t)breg_offset;
tmp.ClearContext();
stack.push_back(tmp);
stack.back().SetValueType(Value::ValueType::LoadAddress);
} break;
case DW_OP_fbreg:
if (exe_ctx) {
if (frame) {
Scalar value;
if (llvm::Error err = frame->GetFrameBaseValue(value))
return err;
int64_t fbreg_offset = opcodes.GetSLEB128(&offset);
value += fbreg_offset;
stack.push_back(value);
stack.back().SetValueType(Value::ValueType::LoadAddress);
} else {
return llvm::createStringError(
"invalid stack frame in context for DW_OP_fbreg opcode");
}
} else {
return llvm::createStringError(
"NULL execution context for DW_OP_fbreg");
}
break;
// OPCODE: DW_OP_nop
// OPERANDS: none
// DESCRIPTION: A place holder. It has no effect on the location stack
// or any of its values.
case DW_OP_nop:
break;
// OPCODE: DW_OP_piece
// OPERANDS: 1
// ULEB128: byte size of the piece
// DESCRIPTION: The operand describes the size in bytes of the piece of
// the object referenced by the DWARF expression whose result is at the top
// of the stack. If the piece is located in a register, but does not occupy
// the entire register, the placement of the piece within that register is
// defined by the ABI.
//
// Many compilers store a single variable in sets of registers, or store a
// variable partially in memory and partially in registers. DW_OP_piece
// provides a way of describing how large a part of a variable a particular
// DWARF expression refers to.
case DW_OP_piece: {
LocationDescriptionKind piece_locdesc = dwarf4_location_description_kind;
// Reset for the next piece.
dwarf4_location_description_kind = Memory;
const uint64_t piece_byte_size = opcodes.GetULEB128(&offset);
if (piece_byte_size > 0) {
Value curr_piece;
if (stack.empty()) {
UpdateValueTypeFromLocationDescription(
log, dwarf_cu, LocationDescriptionKind::Empty);
// In a multi-piece expression, this means that the current piece is
// not available. Fill with zeros for now by resizing the data and
// appending it
curr_piece.ResizeData(piece_byte_size);
// Note that "0" is not a correct value for the unknown bits.
// It would be better to also return a mask of valid bits together
// with the expression result, so the debugger can print missing
// members as "<optimized out>" or something.
::memset(curr_piece.GetBuffer().GetBytes(), 0, piece_byte_size);
pieces.AppendDataToHostBuffer(curr_piece);
} else {
Status error;
// Extract the current piece into "curr_piece"
Value curr_piece_source_value(stack.back());
stack.pop_back();
UpdateValueTypeFromLocationDescription(log, dwarf_cu, piece_locdesc,
&curr_piece_source_value);
const Value::ValueType curr_piece_source_value_type =
curr_piece_source_value.GetValueType();
Scalar &scalar = curr_piece_source_value.GetScalar();
const lldb::addr_t addr = scalar.ULongLong(LLDB_INVALID_ADDRESS);
switch (curr_piece_source_value_type) {
case Value::ValueType::Invalid:
return llvm::createStringError("invalid value type");
case Value::ValueType::LoadAddress:
case Value::ValueType::FileAddress: {
if (target) {
if (curr_piece.ResizeData(piece_byte_size) == piece_byte_size) {
if (target->ReadMemory(addr, curr_piece.GetBuffer().GetBytes(),
piece_byte_size, error,
/*force_live_memory=*/false) !=
piece_byte_size) {
const char *addr_type = (curr_piece_source_value_type ==
Value::ValueType::LoadAddress)
? "load"
: "file";
return llvm::createStringError(
"failed to read memory DW_OP_piece(%" PRIu64
") from %s address 0x%" PRIx64,
piece_byte_size, addr_type, addr);
}
} else {
return llvm::createStringError(
"failed to resize the piece memory buffer for "
"DW_OP_piece(%" PRIu64 ")",
piece_byte_size);
}
}
} break;
case Value::ValueType::HostAddress: {
return llvm::createStringError(
"failed to read memory DW_OP_piece(%" PRIu64
") from host address 0x%" PRIx64,
piece_byte_size, addr);
} break;
case Value::ValueType::Scalar: {
uint32_t bit_size = piece_byte_size * 8;
uint32_t bit_offset = 0;
if (!scalar.ExtractBitfield(
bit_size, bit_offset)) {
return llvm::createStringError(
"unable to extract %" PRIu64 " bytes from a %" PRIu64
" byte scalar value.",
piece_byte_size,
(uint64_t)curr_piece_source_value.GetScalar().GetByteSize());
}
// Create curr_piece with bit_size. By default Scalar
// grows to the nearest host integer type.
llvm::APInt fail_value(1, 0, false);
llvm::APInt ap_int = scalar.UInt128(fail_value);
assert(ap_int.getBitWidth() >= bit_size);
llvm::ArrayRef<uint64_t> buf{ap_int.getRawData(),
ap_int.getNumWords()};
curr_piece.GetScalar() = Scalar(llvm::APInt(bit_size, buf));
} break;
}
// Check if this is the first piece?
if (op_piece_offset == 0) {
// This is the first piece, we should push it back onto the stack
// so subsequent pieces will be able to access this piece and add
// to it.
if (pieces.AppendDataToHostBuffer(curr_piece) == 0) {
return llvm::createStringError("failed to append piece data");
}
} else {
// If this is the second or later piece there should be a value on
// the stack.
if (pieces.GetBuffer().GetByteSize() != op_piece_offset) {
return llvm::createStringError(
"DW_OP_piece for offset %" PRIu64
" but top of stack is of size %" PRIu64,
op_piece_offset, pieces.GetBuffer().GetByteSize());
}
if (pieces.AppendDataToHostBuffer(curr_piece) == 0)
return llvm::createStringError("failed to append piece data");
}
}
op_piece_offset += piece_byte_size;
}
} break;
case DW_OP_bit_piece: // 0x9d ULEB128 bit size, ULEB128 bit offset (DWARF3);
if (stack.size() < 1) {
UpdateValueTypeFromLocationDescription(log, dwarf_cu,
LocationDescriptionKind::Empty);
// Reset for the next piece.
dwarf4_location_description_kind = Memory;
return llvm::createStringError(
"expression stack needs at least 1 item for DW_OP_bit_piece");
} else {
UpdateValueTypeFromLocationDescription(
log, dwarf_cu, dwarf4_location_description_kind, &stack.back());
// Reset for the next piece.
dwarf4_location_description_kind = Memory;
const uint64_t piece_bit_size = opcodes.GetULEB128(&offset);
const uint64_t piece_bit_offset = opcodes.GetULEB128(&offset);
switch (stack.back().GetValueType()) {
case Value::ValueType::Invalid:
return llvm::createStringError(
"unable to extract bit value from invalid value");
case Value::ValueType::Scalar: {
if (!stack.back().GetScalar().ExtractBitfield(piece_bit_size,
piece_bit_offset)) {
return llvm::createStringError(
"unable to extract %" PRIu64 " bit value with %" PRIu64
" bit offset from a %" PRIu64 " bit scalar value.",
piece_bit_size, piece_bit_offset,
(uint64_t)(stack.back().GetScalar().GetByteSize() * 8));
}
} break;
case Value::ValueType::FileAddress:
case Value::ValueType::LoadAddress:
case Value::ValueType::HostAddress:
return llvm::createStringError(
"unable to extract DW_OP_bit_piece(bit_size = %" PRIu64
", bit_offset = %" PRIu64 ") from an address value.",
piece_bit_size, piece_bit_offset);
}
}
break;
// OPCODE: DW_OP_implicit_value
// OPERANDS: 2
// ULEB128 size of the value block in bytes
// uint8_t* block bytes encoding value in target's memory
// representation
// DESCRIPTION: Value is immediately stored in block in the debug info with
// the memory representation of the target.
case DW_OP_implicit_value: {
dwarf4_location_description_kind = Implicit;
const uint32_t len = opcodes.GetULEB128(&offset);
const void *data = opcodes.GetData(&offset, len);
if (!data) {
LLDB_LOG(log, "Evaluate_DW_OP_implicit_value: could not be read data");
return llvm::createStringError("could not evaluate %s",
DW_OP_value_to_name(op));
}
Value result(data, len);
stack.push_back(result);
break;
}
case DW_OP_implicit_pointer: {
dwarf4_location_description_kind = Implicit;
return llvm::createStringError("Could not evaluate %s.",
DW_OP_value_to_name(op));
}
// OPCODE: DW_OP_push_object_address
// OPERANDS: none
// DESCRIPTION: Pushes the address of the object currently being
// evaluated as part of evaluation of a user presented expression. This
// object may correspond to an independent variable described by its own
// DIE or it may be a component of an array, structure, or class whose
// address has been dynamically determined by an earlier step during user
// expression evaluation.
case DW_OP_push_object_address:
if (object_address_ptr)
stack.push_back(*object_address_ptr);
else {
return llvm::createStringError("DW_OP_push_object_address used without "
"specifying an object address");
}
break;
// OPCODE: DW_OP_call2
// OPERANDS:
// uint16_t compile unit relative offset of a DIE
// DESCRIPTION: Performs subroutine calls during evaluation
// of a DWARF expression. The operand is the 2-byte unsigned offset of a
// debugging information entry in the current compilation unit.
//
// Operand interpretation is exactly like that for DW_FORM_ref2.
//
// This operation transfers control of DWARF expression evaluation to the
// DW_AT_location attribute of the referenced DIE. If there is no such
// attribute, then there is no effect. Execution of the DWARF expression of
// a DW_AT_location attribute may add to and/or remove from values on the
// stack. Execution returns to the point following the call when the end of
// the attribute is reached. Values on the stack at the time of the call
// may be used as parameters by the called expression and values left on
// the stack by the called expression may be used as return values by prior
// agreement between the calling and called expressions.
case DW_OP_call2:
return llvm::createStringError("unimplemented opcode DW_OP_call2");
// OPCODE: DW_OP_call4
// OPERANDS: 1
// uint32_t compile unit relative offset of a DIE
// DESCRIPTION: Performs a subroutine call during evaluation of a DWARF
// expression. For DW_OP_call4, the operand is a 4-byte unsigned offset of
// a debugging information entry in the current compilation unit.
//
// Operand interpretation DW_OP_call4 is exactly like that for
// DW_FORM_ref4.
//
// This operation transfers control of DWARF expression evaluation to the
// DW_AT_location attribute of the referenced DIE. If there is no such
// attribute, then there is no effect. Execution of the DWARF expression of
// a DW_AT_location attribute may add to and/or remove from values on the
// stack. Execution returns to the point following the call when the end of
// the attribute is reached. Values on the stack at the time of the call
// may be used as parameters by the called expression and values left on
// the stack by the called expression may be used as return values by prior
// agreement between the calling and called expressions.
case DW_OP_call4:
return llvm::createStringError("unimplemented opcode DW_OP_call4");
// OPCODE: DW_OP_stack_value
// OPERANDS: None
// DESCRIPTION: Specifies that the object does not exist in memory but
// rather is a constant value. The value from the top of the stack is the
// value to be used. This is the actual object value and not the location.
case DW_OP_stack_value:
dwarf4_location_description_kind = Implicit;
stack.back().SetValueType(Value::ValueType::Scalar);
break;
// OPCODE: DW_OP_convert
// OPERANDS: 1
// A ULEB128 that is either a DIE offset of a
// DW_TAG_base_type or 0 for the generic (pointer-sized) type.
//
// DESCRIPTION: Pop the top stack element, convert it to a
// different type, and push the result.
case DW_OP_convert: {
const uint64_t 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)
return llvm::createStringError("no module");
sign = false;
bit_size = module_sp->GetArchitecture().GetAddressByteSize() * 8;
if (!bit_size)
return llvm::createStringError("unspecified architecture");
} else {
// Retrieve the type DIE that the value is being converted to. This
// offset is compile unit relative so we need to fix it up.
const uint64_t abs_die_offset = die_offset + dwarf_cu->GetOffset();
// FIXME: the constness has annoying ripple effects.
DWARFDIE die = const_cast<DWARFUnit *>(dwarf_cu)->GetDIE(abs_die_offset);
if (!die)
return llvm::createStringError(
"cannot resolve DW_OP_convert type DIE");
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)
return llvm::createStringError(
"unsupported type size in DW_OP_convert");
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:
return llvm::createStringError(
"unsupported encoding in DW_OP_convert");
}
}
Scalar &top = stack.back().ResolveValue(exe_ctx);
top.TruncOrExtendTo(bit_size, sign);
break;
}
// OPCODE: DW_OP_call_frame_cfa
// OPERANDS: None
// DESCRIPTION: Specifies a DWARF expression that pushes the value of
// the canonical frame address consistent with the call frame information
// located in .debug_frame (or in the FDEs of the eh_frame section).
case DW_OP_call_frame_cfa:
if (frame) {
// Note that we don't have to parse FDEs because this DWARF expression
// is commonly evaluated with a valid stack frame.
StackID id = frame->GetStackID();
addr_t cfa = id.GetCallFrameAddress();
if (cfa != LLDB_INVALID_ADDRESS) {
stack.push_back(Scalar(cfa));
stack.back().SetValueType(Value::ValueType::LoadAddress);
} else {
return llvm::createStringError(
"stack frame does not include a canonical "
"frame address for DW_OP_call_frame_cfa "
"opcode");
}
} else {
return llvm::createStringError("unvalid stack frame in context for "
"DW_OP_call_frame_cfa opcode");
}
break;
// OPCODE: DW_OP_form_tls_address (or the old pre-DWARFv3 vendor extension
// opcode, DW_OP_GNU_push_tls_address)
// OPERANDS: none
// DESCRIPTION: Pops a TLS offset from the stack, converts it to
// an address in the current thread's thread-local storage block, and
// pushes it on the stack.
case DW_OP_form_tls_address:
case DW_OP_GNU_push_tls_address: {
if (stack.size() < 1) {
if (op == DW_OP_form_tls_address)
return llvm::createStringError(
"DW_OP_form_tls_address needs an argument");
else
return llvm::createStringError(
"DW_OP_GNU_push_tls_address needs an argument");
}
if (!exe_ctx || !module_sp)
return llvm::createStringError("no context to evaluate TLS within");
Thread *thread = exe_ctx->GetThreadPtr();
if (!thread)
return llvm::createStringError("no thread to evaluate TLS within");
// Lookup the TLS block address for this thread and module.
const addr_t tls_file_addr =
stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
const addr_t tls_load_addr =
thread->GetThreadLocalData(module_sp, tls_file_addr);
if (tls_load_addr == LLDB_INVALID_ADDRESS)
return llvm::createStringError(
"no TLS data currently exists for this thread");
stack.back().GetScalar() = tls_load_addr;
stack.back().SetValueType(Value::ValueType::LoadAddress);
} break;
// OPCODE: DW_OP_addrx (DW_OP_GNU_addr_index is the legacy name.)
// OPERANDS: 1
// ULEB128: index to the .debug_addr section
// DESCRIPTION: Pushes an address to the stack from the .debug_addr
// section with the base address specified by the DW_AT_addr_base attribute
// and the 0 based index is the ULEB128 encoded index.
case DW_OP_addrx:
case DW_OP_GNU_addr_index: {
if (!dwarf_cu)
return llvm::createStringError("DW_OP_GNU_addr_index found without a "
"compile unit being specified");
uint64_t index = opcodes.GetULEB128(&offset);
lldb::addr_t value = dwarf_cu->ReadAddressFromDebugAddrSection(index);
stack.push_back(Scalar(value));
if (target &&
target->GetArchitecture().GetCore() == ArchSpec::eCore_wasm32) {
// wasm file sections aren't mapped into memory, therefore addresses can
// never point into a file section and are always LoadAddresses.
stack.back().SetValueType(Value::ValueType::LoadAddress);
} else {
stack.back().SetValueType(Value::ValueType::FileAddress);
}
} break;
// OPCODE: DW_OP_GNU_const_index
// OPERANDS: 1
// ULEB128: index to the .debug_addr section
// DESCRIPTION: Pushes an constant with the size of a machine address to
// the stack from the .debug_addr section with the base address specified
// by the DW_AT_addr_base attribute and the 0 based index is the ULEB128
// encoded index.
case DW_OP_GNU_const_index: {
if (!dwarf_cu) {
return llvm::createStringError("DW_OP_GNU_const_index found without a "
"compile unit being specified");
}
uint64_t index = opcodes.GetULEB128(&offset);
lldb::addr_t value = dwarf_cu->ReadAddressFromDebugAddrSection(index);
stack.push_back(Scalar(value));
} break;
case DW_OP_GNU_entry_value:
case DW_OP_entry_value: {
if (llvm::Error err = Evaluate_DW_OP_entry_value(stack, exe_ctx, reg_ctx,
opcodes, offset, log))
return llvm::createStringError(
"could not evaluate DW_OP_entry_value: %s",
llvm::toString(std::move(err)).c_str());
break;
}
default:
if (dwarf_cu) {
if (dwarf_cu->GetSymbolFileDWARF().ParseVendorDWARFOpcode(
op, opcodes, offset, stack)) {
break;
}
}
return llvm::createStringError(llvm::formatv(
"Unhandled opcode {0} in DWARFExpression", LocationAtom(op)));
}
}
if (stack.empty()) {
// Nothing on the stack, check if we created a piece value from DW_OP_piece
// or DW_OP_bit_piece opcodes
if (pieces.GetBuffer().GetByteSize())
return pieces;
return llvm::createStringError("stack empty after evaluation");
}
UpdateValueTypeFromLocationDescription(
log, dwarf_cu, dwarf4_location_description_kind, &stack.back());
if (log && log->GetVerbose()) {
size_t count = stack.size();
LLDB_LOGF(log,
"Stack after operation has %" PRIu64 " values:", (uint64_t)count);
for (size_t i = 0; i < count; ++i) {
StreamString new_value;
new_value.Printf("[%" PRIu64 "]", (uint64_t)i);
stack[i].Dump(&new_value);
LLDB_LOGF(log, " %s", new_value.GetData());
}
}
return stack.back();
}
bool DWARFExpression::ParseDWARFLocationList(
const DWARFUnit *dwarf_cu, const DataExtractor &data,
DWARFExpressionList *location_list) {
location_list->Clear();
std::unique_ptr<llvm::DWARFLocationTable> loctable_up =
dwarf_cu->GetLocationTable(data);
Log *log = GetLog(LLDBLog::Expressions);
auto lookup_addr =
[&](uint32_t index) -> std::optional<llvm::object::SectionedAddress> {
addr_t address = dwarf_cu->ReadAddressFromDebugAddrSection(index);
if (address == LLDB_INVALID_ADDRESS)
return std::nullopt;
return llvm::object::SectionedAddress{address};
};
auto process_list = [&](llvm::Expected<llvm::DWARFLocationExpression> loc) {
if (!loc) {
LLDB_LOG_ERROR(log, loc.takeError(), "{0}");
return true;
}
auto buffer_sp =
std::make_shared<DataBufferHeap>(loc->Expr.data(), loc->Expr.size());
DWARFExpression expr = DWARFExpression(DataExtractor(
buffer_sp, data.GetByteOrder(), data.GetAddressByteSize()));
location_list->AddExpression(loc->Range->LowPC, loc->Range->HighPC, expr);
return true;
};
llvm::Error error = loctable_up->visitAbsoluteLocationList(
0, llvm::object::SectionedAddress{dwarf_cu->GetBaseAddress()},
lookup_addr, process_list);
location_list->Sort();
if (error) {
LLDB_LOG_ERROR(log, std::move(error), "{0}");
return false;
}
return true;
}
bool DWARFExpression::MatchesOperand(
StackFrame &frame, const Instruction::Operand &operand) const {
using namespace OperandMatchers;
RegisterContextSP reg_ctx_sp = frame.GetRegisterContext();
if (!reg_ctx_sp) {
return false;
}
DataExtractor opcodes(m_data);
lldb::offset_t op_offset = 0;
uint8_t opcode = opcodes.GetU8(&op_offset);
if (opcode == DW_OP_fbreg) {
int64_t offset = opcodes.GetSLEB128(&op_offset);
DWARFExpressionList *fb_expr = frame.GetFrameBaseExpression(nullptr);
if (!fb_expr) {
return false;
}
auto recurse = [&frame, fb_expr](const Instruction::Operand &child) {
return fb_expr->MatchesOperand(frame, child);
};
if (!offset &&
MatchUnaryOp(MatchOpType(Instruction::Operand::Type::Dereference),
recurse)(operand)) {
return true;
}
return MatchUnaryOp(
MatchOpType(Instruction::Operand::Type::Dereference),
MatchBinaryOp(MatchOpType(Instruction::Operand::Type::Sum),
MatchImmOp(offset), recurse))(operand);
}
bool dereference = false;
const RegisterInfo *reg = nullptr;
int64_t offset = 0;
if (opcode >= DW_OP_reg0 && opcode <= DW_OP_reg31) {
reg = reg_ctx_sp->GetRegisterInfo(m_reg_kind, opcode - DW_OP_reg0);
} else if (opcode >= DW_OP_breg0 && opcode <= DW_OP_breg31) {
offset = opcodes.GetSLEB128(&op_offset);
reg = reg_ctx_sp->GetRegisterInfo(m_reg_kind, opcode - DW_OP_breg0);
} else if (opcode == DW_OP_regx) {
uint32_t reg_num = static_cast<uint32_t>(opcodes.GetULEB128(&op_offset));
reg = reg_ctx_sp->GetRegisterInfo(m_reg_kind, reg_num);
} else if (opcode == DW_OP_bregx) {
uint32_t reg_num = static_cast<uint32_t>(opcodes.GetULEB128(&op_offset));
offset = opcodes.GetSLEB128(&op_offset);
reg = reg_ctx_sp->GetRegisterInfo(m_reg_kind, reg_num);
} else {
return false;
}
if (!reg) {
return false;
}
if (dereference) {
if (!offset &&
MatchUnaryOp(MatchOpType(Instruction::Operand::Type::Dereference),
MatchRegOp(*reg))(operand)) {
return true;
}
return MatchUnaryOp(
MatchOpType(Instruction::Operand::Type::Dereference),
MatchBinaryOp(MatchOpType(Instruction::Operand::Type::Sum),
MatchRegOp(*reg),
MatchImmOp(offset)))(operand);
} else {
return MatchRegOp(*reg)(operand);
}
}
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