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//===-- DWARFExpression.h ---------------------------------------*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
#ifndef liblldb_DWARFExpression_h_
#define liblldb_DWARFExpression_h_
#include "lldb/Core/Address.h"
#include "lldb/Core/Disassembler.h"
#include "lldb/Utility/DataExtractor.h"
#include "lldb/Utility/Scalar.h"
#include "lldb/Utility/Status.h"
#include "lldb/lldb-private.h"
#include <functional>
class DWARFUnit;
namespace lldb_private {
/// \class DWARFExpression DWARFExpression.h
/// "lldb/Expression/DWARFExpression.h" Encapsulates a DWARF location
/// expression and interprets it.
///
/// DWARF location expressions are used in two ways by LLDB. The first
/// use is to find entities specified in the debug information, since their
/// locations are specified in precisely this language. The second is to
/// interpret expressions without having to run the target in cases where the
/// overhead from copying JIT-compiled code into the target is too high or
/// where the target cannot be run. This class encapsulates a single DWARF
/// location expression or a location list and interprets it.
class DWARFExpression {
public:
enum LocationListFormat : uint8_t {
NonLocationList, // Not a location list
RegularLocationList, // Location list format used in non-split dwarf files
SplitDwarfLocationList, // Location list format used in pre-DWARF v5 split
// dwarf files (.debug_loc.dwo)
LocLists, // Location list format used in DWARF v5
// (.debug_loclists/.debug_loclists.dwo).
};
/// Constructor
explicit DWARFExpression(DWARFUnit *dwarf_cu);
/// Constructor
///
/// \param[in] data
/// A data extractor configured to read the DWARF location expression's
/// bytecode.
///
/// \param[in] data_offset
/// The offset of the location expression in the extractor.
///
/// \param[in] data_length
/// The byte length of the location expression.
DWARFExpression(lldb::ModuleSP module, const DataExtractor &data,
DWARFUnit *dwarf_cu, lldb::offset_t data_offset,
lldb::offset_t data_length);
/// Destructor
virtual ~DWARFExpression();
/// Print the description of the expression to a stream
///
/// \param[in] s
/// The stream to print to.
///
/// \param[in] level
/// The level of verbosity to use.
///
/// \param[in] location_list_base_addr
/// If this is a location list based expression, this is the
/// address of the object that owns it. NOTE: this value is
/// different from the DWARF version of the location list base
/// address which is compile unit relative. This base address
/// is the address of the object that owns the location list.
///
/// \param[in] abi
/// An optional ABI plug-in that can be used to resolve register
/// names.
void GetDescription(Stream *s, lldb::DescriptionLevel level,
lldb::addr_t location_list_base_addr, ABI *abi) const;
/// Return true if the location expression contains data
bool IsValid() const;
/// Return true if a location list was provided
bool IsLocationList() const;
/// Search for a load address in the location list
///
/// \param[in] process
/// The process to use when resolving the load address
///
/// \param[in] addr
/// The address to resolve
///
/// \return
/// True if IsLocationList() is true and the address was found;
/// false otherwise.
// bool
// LocationListContainsLoadAddress (Process* process, const Address &addr)
// const;
//
bool LocationListContainsAddress(lldb::addr_t loclist_base_addr,
lldb::addr_t addr) const;
/// If a location is not a location list, return true if the location
/// contains a DW_OP_addr () opcode in the stream that matches \a file_addr.
/// If file_addr is LLDB_INVALID_ADDRESS, the this function will return true
/// if the variable there is any DW_OP_addr in a location that (yet still is
/// NOT a location list). This helps us detect if a variable is a global or
/// static variable since there is no other indication from DWARF debug
/// info.
///
/// \param[in] op_addr_idx
/// The DW_OP_addr index to retrieve in case there is more than
/// one DW_OP_addr opcode in the location byte stream.
///
/// \param[out] error
/// If the location stream contains unknown DW_OP opcodes or the
/// data is missing, \a error will be set to \b true.
///
/// \return
/// LLDB_INVALID_ADDRESS if the location doesn't contain a
/// DW_OP_addr for \a op_addr_idx, otherwise a valid file address
lldb::addr_t GetLocation_DW_OP_addr(uint32_t op_addr_idx, bool &error) const;
bool Update_DW_OP_addr(lldb::addr_t file_addr);
void SetModule(const lldb::ModuleSP &module) { m_module_wp = module; }
bool ContainsThreadLocalStorage() const;
bool LinkThreadLocalStorage(
lldb::ModuleSP new_module_sp,
std::function<lldb::addr_t(lldb::addr_t file_addr)> const
&link_address_callback);
/// Make the expression parser read its location information from a given
/// data source. Does not change the offset and length
///
/// \param[in] data
/// A data extractor configured to read the DWARF location expression's
/// bytecode.
void SetOpcodeData(const DataExtractor &data);
/// Make the expression parser read its location information from a given
/// data source
///
/// \param[in] module_sp
/// The module that defines the DWARF expression.
///
/// \param[in] data
/// A data extractor configured to read the DWARF location expression's
/// bytecode.
///
/// \param[in] data_offset
/// The offset of the location expression in the extractor.
///
/// \param[in] data_length
/// The byte length of the location expression.
void SetOpcodeData(lldb::ModuleSP module_sp, const DataExtractor &data,
lldb::offset_t data_offset, lldb::offset_t data_length);
/// Copy the DWARF location expression into a local buffer.
///
/// It is a good idea to copy the data so we don't keep the entire object
/// file worth of data around just for a few bytes of location expression.
/// LLDB typically will mmap the entire contents of debug information files,
/// and if we use SetOpcodeData, it will get a shared reference to all of
/// this data for the and cause the object file to have to stay around. Even
/// worse, a very very large ".a" that contains one or more .o files could
/// end up being referenced. Location lists are typically small so even
/// though we are copying the data, it shouldn't amount to that much for the
/// variables we end up parsing.
///
/// \param[in] module_sp
/// The module that defines the DWARF expression.
///
/// \param[in] data
/// A data extractor configured to read and copy the DWARF
/// location expression's bytecode.
///
/// \param[in] data_offset
/// The offset of the location expression in the extractor.
///
/// \param[in] data_length
/// The byte length of the location expression.
void CopyOpcodeData(lldb::ModuleSP module_sp, const DataExtractor &data,
lldb::offset_t data_offset, lldb::offset_t data_length);
void CopyOpcodeData(const void *data, lldb::offset_t data_length,
lldb::ByteOrder byte_order, uint8_t addr_byte_size);
void CopyOpcodeData(uint64_t const_value,
lldb::offset_t const_value_byte_size,
uint8_t addr_byte_size);
/// Tells the expression that it refers to a location list.
///
/// \param[in] slide
/// This value should be a slide that is applied to any values
/// in the location list data so the values become zero based
/// offsets into the object that owns the location list. We need
/// to make location lists relative to the objects that own them
/// so we can relink addresses on the fly.
void SetLocationListSlide(lldb::addr_t slide);
/// Return the call-frame-info style register kind
int GetRegisterKind();
/// Set the call-frame-info style register kind
///
/// \param[in] reg_kind
/// The register kind.
void SetRegisterKind(lldb::RegisterKind reg_kind);
/// Wrapper for the static evaluate function that accepts an
/// ExecutionContextScope instead of an ExecutionContext and uses member
/// variables to populate many operands
bool 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;
/// Wrapper for the static evaluate function that uses member variables to
/// populate many operands
bool Evaluate(ExecutionContext *exe_ctx, RegisterContext *reg_ctx,
lldb::addr_t loclist_base_load_addr,
const Value *initial_value_ptr, const Value *object_address_ptr,
Value &result, Status *error_ptr) const;
/// Evaluate a DWARF location expression in a particular context
///
/// \param[in] exe_ctx
/// The execution context in which to evaluate the location
/// expression. The location expression may access the target's
/// memory, especially if it comes from the expression parser.
///
/// \param[in] opcode_ctx
/// The module which defined the expression.
///
/// \param[in] opcodes
/// This is a static method so the opcodes need to be provided
/// explicitly.
///
/// \param[in] expr_locals
/// If the location expression was produced by the expression parser,
/// the list of local variables referenced by the DWARF expression.
/// This list should already have been populated during parsing;
/// the DWARF expression refers to variables by index. Can be NULL if
/// the location expression uses no locals.
///
/// \param[in] decl_map
/// If the location expression was produced by the expression parser,
/// the list of external variables referenced by the location
/// expression. Can be NULL if the location expression uses no
/// external variables.
///
/// \param[in] reg_ctx
/// An optional parameter which provides a RegisterContext for use
/// when evaluating the expression (i.e. for fetching register values).
/// Normally this will come from the ExecutionContext's StackFrame but
/// in the case where an expression needs to be evaluated while building
/// the stack frame list, this short-cut is available.
///
/// \param[in] offset
/// The offset of the location expression in the data extractor.
///
/// \param[in] length
/// The length in bytes of the location expression.
///
/// \param[in] reg_set
/// The call-frame-info style register kind.
///
/// \param[in] initial_value_ptr
/// A value to put on top of the interpreter stack before evaluating
/// the expression, if the expression is parametrized. Can be NULL.
///
/// \param[in] result
/// A value into which the result of evaluating the expression is
/// to be placed.
///
/// \param[in] error_ptr
/// If non-NULL, used to report errors in expression evaluation.
///
/// \return
/// True on success; false otherwise. If error_ptr is non-NULL,
/// details of the failure are provided through it.
static bool Evaluate(ExecutionContext *exe_ctx, RegisterContext *reg_ctx,
lldb::ModuleSP opcode_ctx, const DataExtractor &opcodes,
DWARFUnit *dwarf_cu, const lldb::offset_t offset,
const lldb::offset_t length,
const lldb::RegisterKind reg_set,
const Value *initial_value_ptr,
const Value *object_address_ptr, Value &result,
Status *error_ptr);
bool GetExpressionData(DataExtractor &data) const {
data = m_data;
return data.GetByteSize() > 0;
}
bool DumpLocationForAddress(Stream *s, lldb::DescriptionLevel level,
lldb::addr_t loclist_base_load_addr,
lldb::addr_t address, ABI *abi);
static size_t LocationListSize(const DWARFUnit *dwarf_cu,
const DataExtractor &debug_loc_data,
lldb::offset_t offset);
static bool PrintDWARFExpression(Stream &s, const DataExtractor &data,
int address_size, int dwarf_ref_size,
bool location_expression);
static void PrintDWARFLocationList(Stream &s, const DWARFUnit *cu,
const DataExtractor &debug_loc_data,
lldb::offset_t offset);
bool MatchesOperand(StackFrame &frame, const Instruction::Operand &op);
protected:
/// Pretty-prints the location expression to a stream
///
/// \param[in] stream
/// The stream to use for pretty-printing.
///
/// \param[in] offset
/// The offset into the data buffer of the opcodes to be printed.
///
/// \param[in] length
/// The length in bytes of the opcodes to be printed.
///
/// \param[in] level
/// The level of detail to use in pretty-printing.
///
/// \param[in] abi
/// An optional ABI plug-in that can be used to resolve register
/// names.
void DumpLocation(Stream *s, lldb::offset_t offset, lldb::offset_t length,
lldb::DescriptionLevel level, ABI *abi) const;
bool GetLocation(lldb::addr_t base_addr, lldb::addr_t pc,
lldb::offset_t &offset, lldb::offset_t &len);
static bool AddressRangeForLocationListEntry(
const DWARFUnit *dwarf_cu, const DataExtractor &debug_loc_data,
lldb::offset_t *offset_ptr, lldb::addr_t &low_pc, lldb::addr_t &high_pc);
bool GetOpAndEndOffsets(StackFrame &frame, lldb::offset_t &op_offset,
lldb::offset_t &end_offset);
/// Classes that inherit from DWARFExpression can see and modify these
lldb::ModuleWP m_module_wp; ///< Module which defined this expression.
DataExtractor m_data; ///< A data extractor capable of reading opcode bytes
DWARFUnit *m_dwarf_cu; ///< The DWARF compile unit this expression
///belongs to. It is used
///< to evaluate values indexing into the .debug_addr section (e.g.
///< DW_OP_GNU_addr_index, DW_OP_GNU_const_index)
lldb::RegisterKind
m_reg_kind; ///< One of the defines that starts with LLDB_REGKIND_
lldb::addr_t m_loclist_slide; ///< A value used to slide the location list
///offsets so that
///< they are relative to the object that owns the location list
///< (the function for frame base and variable location lists)
};
} // namespace lldb_private
#endif // liblldb_DWARFExpression_h_