value_analysis

value_reg_edge(EA:address, Reg:register, EA_reg1:address, Reg1:register, Multiplier:number, Offset:number)

This module performs a basic value analysis.

The value of a register at a point (ea) is expressed as the value of another at another point (EA_reg1) multiplied by a multiplier plus an offset:

val(Reg,EA) = val(Reg1,EA_reg1)* Multiplier+ Offset

In some cases we can obtain a term of the form:

val(Reg,EA) = Offset

If we can obtain that the register is assigned a constant

val(Reg,EA) = Unknown * Multiplier+ Offset

If we detect a loop where the register gets incremented ‘Multiplier’ in each iteration

The analysis first computes value_reg_edge which are facts of the form above defined for different instruction and using the def-use chains.

Then, we have a propagation phase where value_reg is computed. This phase chains individual value_reg_edge together. In addition to chaining edges together it takes care of cases such as two registers added together or substracted if it turns out that they can be expressed in terms of the same register. It also detects possible loops.

This propagation is limited in the number of steps using step_limit to ensure termination and efficiency.

As a result, we might obtain more than one ‘value’ for a certain register at a certain location. best_value_reg selects only one of these values prioritizing the two special cases from above (constant or loop) and considering the value with most steps.

Uses: arch.memory_access, arch.move_reg_reg, arch.reg_arithmetic_operation, instruction, instruction_get_dest_op, next, op_regdirect_contains_reg, track_register

Recursive: const_value_reg_used, function_inference.function_entry_initial, no_return_call_propagated, next_end, may_fallthrough, jump_table_candidate, block_candidate_boundaries, unresolved_interval_order, inferred_main_in_reg, reg_def_use.return_val_used, inter_procedural_edge, compare_and_jump_immediate, block_limit, value_reg_edge, block_next, reg_has_base_image, stack_def_use.block_last_def, possible_target_from, no_return_block, indefinite_litpool_ref, stack_def_use.used_in_block, adjusts_stack_in_block, split_load_total_points, jump_table_candidate_refined, overlap_with_litpool, value_reg_limit, code_in_block_candidate, candidate_block_is_not_padding, likely_fallthrough, arch.reg_relative_load, arm_jump_table_cmp_limit, value_reg_unsupported, nop_in_padding_candidate, arm_jump_table_block_start, __agg_subclause2, transition_block_limit, block_overlap, no_return_call, data_segment, jump_table_element_access, reg_def_use.flow_def, arm_jump_table_skip_first_entry, block_total_points, stack_def_use.defined_in_block, reg_def_use.ambiguous_last_def_in_block, straight_line_def_used, basic_target, symbol_minus_symbol_litpool_access_pattern, value_reg, reg_def_use.live_var_used, compare_and_jump_indirect_op_valid, litpool_ref, padding_block_candidate, self_contained_segment, data_in_code_propagate, unresolved_interval, unlikely_have_symbolic_immediate, symbolic_expr_from_relocation, hi_load_prop, block_points, wis_memo, split_load_for_symbolization, arm_jump_table_data_block_limit, adrp_used, known_block, wis_has_prior, candidate_block_is_padding, no_return_call_refined, data_in_code, reg_def_use.used, is_padding, reg_def_use.ref_in_block, base_relative_operand, def_used_for_address, reg_def_use.live_var_at_prior_used, block_heuristic, relative_address_start, tls_get_addr, __agg_subclause6, instruction_memory_access_size, start_function, arm_jump_table_candidate, first_block_in_byte_interval, stack_base_reg_move, __agg_subclause3, jump_table_target, base_relative_operation, resolved_reaches, next_start, reg_def_use.live_var_def, must_fallthrough, next_type, arm_jump_table_candidate_start, next_block_in_byte_interval, __agg_single3, split_load, indexed_pc_relative_load_relative, block_instruction_next, stack_def_use.live_var_used_in_block, cmp_defines, block, reg_def_use.block_last_def, overlapping_instruction, code_in_block, no_value_reg_limit, jump_table_signed, impossible_block, block_boundaries, wis_prior, composite_data_access, relocation_adjustment_total, discarded_block, stack_def_use.last_def_in_block, indexed_pc_relative_load, __agg_single6, stack_def_use.live_var_at_block_end, after_end, split_load_candidate, incomplete_block, straight_line_last_def, jump_table_max, block_points_proportional, wis_schedule, arm_jump_table_data_block, compare_and_jump_register, block_candidate_dependency_edge, reg_has_got, data_block_candidate, got_relative_operand, contains_plausible_instr_seq, reg_def_use.ambiguous_block_last_def, invalid_jump_table_candidate, possible_target, relative_address, cmp_reg_to_reg, reg_def_use.def_used, cinf_ldr_add_pc, block_implies_block, contains_implausible_instr_seq, split_load_point, call_tls_get_addr, unresolved_block, split_load_operand, inferred_main_dispatch, gp_relative_operand, code_in_block_candidate_refined, reg_reg_arithmetic_operation_defs, litpool_symbolic_operand, data_access, init_symbol_minus_symbol_candidate_arm, plt_block, invalid, litpool_boundaries, segment_target_range, correlated_live_reg, arm_jump_table_block_instruction, simple_data_access_pattern, reg_def_use.live_var_at_block_end, reg_def_use.defined_in_block, block_last_instruction, flags_and_jump_pair, split_load_conflict, data_block_limit, last_value_reg_limit, reg_used_for, initialized_data_segment, __agg_subclause7, stack_def_use.live_var_at_prior_used, jump_table_start, unresolved_block_overlap, arch.extend_load, stack_def_use.def_used, init_ldr_add_pc, litpool_confidence, tls_desc_call, common_tail, stack_def_use.ref_in_block, arch.simple_data_load, reg_def_use.used_in_block, base_relative_jump, branch_to_calculated_pc_rel_addr, stack_def_use.live_var_def, wis_schedule_iter, jump_table_prelude, negative_block_heuristic, relocation_adjustment, compare_and_jump_indirect, reg_def_use.last_def_in_block, relative_jump_table_entry_candidate, discarded_split_load, __agg_single2, padding_block_limit, reg_def_use.return_block_end, plt_entry, stack_def_use.live_var_used

value_reg(EA:address, Reg:register, EA_reg1:address, Reg1:reg_nullable, Multiplier:number, Offset:number, Steps:unsigned)

best_value_reg(EA:address, Reg:register, EA_from:address, Multiplier:number, Offset:number, type:symbol)

bshru_wrapper(Lhs:number, Rhs:number, Res:number)

For logical right shift in 32-bit ISA, the LHS value’s upper 32-bit needs to be masked out.

WARNING: Predicate not present in compiled Datalog program (Dead Code)

value_reg_unsupported(EA:address, Reg:register)

A register is defined using an unknown value This predicate is used to create trivial leaf edges in the value_reg graph step_limit .

Uses: arch.call, arch.memory_access, arch.move_reg_reg, track_register

Recursive: const_value_reg_used, function_inference.function_entry_initial, no_return_call_propagated, next_end, may_fallthrough, jump_table_candidate, block_candidate_boundaries, unresolved_interval_order, inferred_main_in_reg, reg_def_use.return_val_used, inter_procedural_edge, compare_and_jump_immediate, block_limit, value_reg_edge, block_next, reg_has_base_image, stack_def_use.block_last_def, possible_target_from, no_return_block, indefinite_litpool_ref, stack_def_use.used_in_block, adjusts_stack_in_block, split_load_total_points, jump_table_candidate_refined, overlap_with_litpool, value_reg_limit, code_in_block_candidate, candidate_block_is_not_padding, likely_fallthrough, arch.reg_relative_load, arm_jump_table_cmp_limit, value_reg_unsupported, nop_in_padding_candidate, arm_jump_table_block_start, __agg_subclause2, transition_block_limit, block_overlap, no_return_call, data_segment, jump_table_element_access, reg_def_use.flow_def, arm_jump_table_skip_first_entry, block_total_points, stack_def_use.defined_in_block, reg_def_use.ambiguous_last_def_in_block, straight_line_def_used, basic_target, symbol_minus_symbol_litpool_access_pattern, value_reg, reg_def_use.live_var_used, compare_and_jump_indirect_op_valid, litpool_ref, padding_block_candidate, self_contained_segment, data_in_code_propagate, unresolved_interval, unlikely_have_symbolic_immediate, symbolic_expr_from_relocation, hi_load_prop, block_points, wis_memo, split_load_for_symbolization, arm_jump_table_data_block_limit, adrp_used, known_block, wis_has_prior, candidate_block_is_padding, no_return_call_refined, data_in_code, reg_def_use.used, is_padding, reg_def_use.ref_in_block, base_relative_operand, def_used_for_address, reg_def_use.live_var_at_prior_used, block_heuristic, relative_address_start, tls_get_addr, __agg_subclause6, instruction_memory_access_size, start_function, arm_jump_table_candidate, first_block_in_byte_interval, stack_base_reg_move, __agg_subclause3, jump_table_target, base_relative_operation, resolved_reaches, next_start, reg_def_use.live_var_def, must_fallthrough, next_type, arm_jump_table_candidate_start, next_block_in_byte_interval, __agg_single3, split_load, indexed_pc_relative_load_relative, block_instruction_next, stack_def_use.live_var_used_in_block, cmp_defines, block, reg_def_use.block_last_def, overlapping_instruction, code_in_block, no_value_reg_limit, jump_table_signed, impossible_block, block_boundaries, wis_prior, composite_data_access, relocation_adjustment_total, discarded_block, stack_def_use.last_def_in_block, indexed_pc_relative_load, __agg_single6, stack_def_use.live_var_at_block_end, after_end, split_load_candidate, incomplete_block, straight_line_last_def, jump_table_max, block_points_proportional, wis_schedule, arm_jump_table_data_block, compare_and_jump_register, block_candidate_dependency_edge, reg_has_got, data_block_candidate, got_relative_operand, contains_plausible_instr_seq, reg_def_use.ambiguous_block_last_def, invalid_jump_table_candidate, possible_target, relative_address, cmp_reg_to_reg, reg_def_use.def_used, cinf_ldr_add_pc, block_implies_block, contains_implausible_instr_seq, split_load_point, call_tls_get_addr, unresolved_block, split_load_operand, inferred_main_dispatch, gp_relative_operand, code_in_block_candidate_refined, reg_reg_arithmetic_operation_defs, litpool_symbolic_operand, data_access, init_symbol_minus_symbol_candidate_arm, plt_block, invalid, litpool_boundaries, segment_target_range, correlated_live_reg, arm_jump_table_block_instruction, simple_data_access_pattern, reg_def_use.live_var_at_block_end, reg_def_use.defined_in_block, block_last_instruction, flags_and_jump_pair, split_load_conflict, data_block_limit, last_value_reg_limit, reg_used_for, initialized_data_segment, __agg_subclause7, stack_def_use.live_var_at_prior_used, jump_table_start, unresolved_block_overlap, arch.extend_load, stack_def_use.def_used, init_ldr_add_pc, litpool_confidence, tls_desc_call, common_tail, stack_def_use.ref_in_block, arch.simple_data_load, reg_def_use.used_in_block, base_relative_jump, branch_to_calculated_pc_rel_addr, stack_def_use.live_var_def, wis_schedule_iter, jump_table_prelude, negative_block_heuristic, relocation_adjustment, compare_and_jump_indirect, reg_def_use.last_def_in_block, relative_jump_table_entry_candidate, discarded_split_load, __agg_single2, padding_block_limit, reg_def_use.return_block_end, plt_entry, stack_def_use.live_var_used

step_limit(Limit:unsigned)

reg_reg_arithmetic_operation_defs(EA:address, Reg_def:register, EA_def1:address, Reg1:register, EA_def2:address, Reg2:register, Mult:number, Offset:number)

This is an auxiliary predicate used for computing value_reg. It captures an instruction at EA that defines register Reg_def by operating with two register Reg1 and Reg2 defined at EA_def1 and EA_def1.

The operation is Reg_def = Reg1 + Reg2 * Mult + Offset.

Uses: arch.reg_reg_arithmetic_operation

Recursive: const_value_reg_used, function_inference.function_entry_initial, no_return_call_propagated, next_end, may_fallthrough, jump_table_candidate, block_candidate_boundaries, unresolved_interval_order, inferred_main_in_reg, reg_def_use.return_val_used, inter_procedural_edge, compare_and_jump_immediate, block_limit, value_reg_edge, block_next, reg_has_base_image, stack_def_use.block_last_def, possible_target_from, no_return_block, indefinite_litpool_ref, stack_def_use.used_in_block, adjusts_stack_in_block, split_load_total_points, jump_table_candidate_refined, overlap_with_litpool, value_reg_limit, code_in_block_candidate, candidate_block_is_not_padding, likely_fallthrough, arch.reg_relative_load, arm_jump_table_cmp_limit, value_reg_unsupported, nop_in_padding_candidate, arm_jump_table_block_start, __agg_subclause2, transition_block_limit, block_overlap, no_return_call, data_segment, jump_table_element_access, reg_def_use.flow_def, arm_jump_table_skip_first_entry, block_total_points, stack_def_use.defined_in_block, reg_def_use.ambiguous_last_def_in_block, straight_line_def_used, basic_target, symbol_minus_symbol_litpool_access_pattern, value_reg, reg_def_use.live_var_used, compare_and_jump_indirect_op_valid, litpool_ref, padding_block_candidate, self_contained_segment, data_in_code_propagate, unresolved_interval, unlikely_have_symbolic_immediate, symbolic_expr_from_relocation, hi_load_prop, block_points, wis_memo, split_load_for_symbolization, arm_jump_table_data_block_limit, adrp_used, known_block, wis_has_prior, candidate_block_is_padding, no_return_call_refined, data_in_code, reg_def_use.used, is_padding, reg_def_use.ref_in_block, base_relative_operand, def_used_for_address, reg_def_use.live_var_at_prior_used, block_heuristic, relative_address_start, tls_get_addr, __agg_subclause6, instruction_memory_access_size, start_function, arm_jump_table_candidate, first_block_in_byte_interval, stack_base_reg_move, __agg_subclause3, jump_table_target, base_relative_operation, resolved_reaches, next_start, reg_def_use.live_var_def, must_fallthrough, next_type, arm_jump_table_candidate_start, next_block_in_byte_interval, __agg_single3, split_load, indexed_pc_relative_load_relative, block_instruction_next, stack_def_use.live_var_used_in_block, cmp_defines, block, reg_def_use.block_last_def, overlapping_instruction, code_in_block, no_value_reg_limit, jump_table_signed, impossible_block, block_boundaries, wis_prior, composite_data_access, relocation_adjustment_total, discarded_block, stack_def_use.last_def_in_block, indexed_pc_relative_load, __agg_single6, stack_def_use.live_var_at_block_end, after_end, split_load_candidate, incomplete_block, straight_line_last_def, jump_table_max, block_points_proportional, wis_schedule, arm_jump_table_data_block, compare_and_jump_register, block_candidate_dependency_edge, reg_has_got, data_block_candidate, got_relative_operand, contains_plausible_instr_seq, reg_def_use.ambiguous_block_last_def, invalid_jump_table_candidate, possible_target, relative_address, cmp_reg_to_reg, reg_def_use.def_used, cinf_ldr_add_pc, block_implies_block, contains_implausible_instr_seq, split_load_point, call_tls_get_addr, unresolved_block, split_load_operand, inferred_main_dispatch, gp_relative_operand, code_in_block_candidate_refined, reg_reg_arithmetic_operation_defs, litpool_symbolic_operand, data_access, init_symbol_minus_symbol_candidate_arm, plt_block, invalid, litpool_boundaries, segment_target_range, correlated_live_reg, arm_jump_table_block_instruction, simple_data_access_pattern, reg_def_use.live_var_at_block_end, reg_def_use.defined_in_block, block_last_instruction, flags_and_jump_pair, split_load_conflict, data_block_limit, last_value_reg_limit, reg_used_for, initialized_data_segment, __agg_subclause7, stack_def_use.live_var_at_prior_used, jump_table_start, unresolved_block_overlap, arch.extend_load, stack_def_use.def_used, init_ldr_add_pc, litpool_confidence, tls_desc_call, common_tail, stack_def_use.ref_in_block, arch.simple_data_load, reg_def_use.used_in_block, base_relative_jump, branch_to_calculated_pc_rel_addr, stack_def_use.live_var_def, wis_schedule_iter, jump_table_prelude, negative_block_heuristic, relocation_adjustment, compare_and_jump_indirect, reg_def_use.last_def_in_block, relative_jump_table_entry_candidate, discarded_split_load, __agg_single2, padding_block_limit, reg_def_use.return_block_end, plt_entry, stack_def_use.live_var_used

value_reg_max_mult(EA:address, Reg:register, MaxMult:number)

const_value_reg_used(UsedEA:address, EADef:address, EARegDef:address, Reg:register, Value:number)

A constant value is used in a data access.

EADef: The address where Value was originally defined (which may not necessarily be where Reg is defined, if that value is moved to a different register later).

EARegDef: The address where Reg is defined as Value. Often EADef = EARegDef.

Used by: symbolic_operand_attribute, symbolic_operand_candidate, tls_relative_operand

Recursive: const_value_reg_used, function_inference.function_entry_initial, no_return_call_propagated, next_end, may_fallthrough, jump_table_candidate, block_candidate_boundaries, unresolved_interval_order, inferred_main_in_reg, reg_def_use.return_val_used, inter_procedural_edge, compare_and_jump_immediate, block_limit, value_reg_edge, block_next, reg_has_base_image, stack_def_use.block_last_def, possible_target_from, no_return_block, indefinite_litpool_ref, stack_def_use.used_in_block, adjusts_stack_in_block, split_load_total_points, jump_table_candidate_refined, overlap_with_litpool, value_reg_limit, code_in_block_candidate, candidate_block_is_not_padding, likely_fallthrough, arch.reg_relative_load, arm_jump_table_cmp_limit, value_reg_unsupported, nop_in_padding_candidate, arm_jump_table_block_start, __agg_subclause2, transition_block_limit, block_overlap, no_return_call, data_segment, jump_table_element_access, reg_def_use.flow_def, arm_jump_table_skip_first_entry, block_total_points, stack_def_use.defined_in_block, reg_def_use.ambiguous_last_def_in_block, straight_line_def_used, basic_target, symbol_minus_symbol_litpool_access_pattern, value_reg, reg_def_use.live_var_used, compare_and_jump_indirect_op_valid, litpool_ref, padding_block_candidate, self_contained_segment, data_in_code_propagate, unresolved_interval, unlikely_have_symbolic_immediate, symbolic_expr_from_relocation, hi_load_prop, block_points, wis_memo, split_load_for_symbolization, arm_jump_table_data_block_limit, adrp_used, known_block, wis_has_prior, candidate_block_is_padding, no_return_call_refined, data_in_code, reg_def_use.used, is_padding, reg_def_use.ref_in_block, base_relative_operand, def_used_for_address, reg_def_use.live_var_at_prior_used, block_heuristic, relative_address_start, tls_get_addr, __agg_subclause6, instruction_memory_access_size, start_function, arm_jump_table_candidate, first_block_in_byte_interval, stack_base_reg_move, __agg_subclause3, jump_table_target, base_relative_operation, resolved_reaches, next_start, reg_def_use.live_var_def, must_fallthrough, next_type, arm_jump_table_candidate_start, next_block_in_byte_interval, __agg_single3, split_load, indexed_pc_relative_load_relative, block_instruction_next, stack_def_use.live_var_used_in_block, cmp_defines, block, reg_def_use.block_last_def, overlapping_instruction, code_in_block, no_value_reg_limit, jump_table_signed, impossible_block, block_boundaries, wis_prior, composite_data_access, relocation_adjustment_total, discarded_block, stack_def_use.last_def_in_block, indexed_pc_relative_load, __agg_single6, stack_def_use.live_var_at_block_end, after_end, split_load_candidate, incomplete_block, straight_line_last_def, jump_table_max, block_points_proportional, wis_schedule, arm_jump_table_data_block, compare_and_jump_register, block_candidate_dependency_edge, reg_has_got, data_block_candidate, got_relative_operand, contains_plausible_instr_seq, reg_def_use.ambiguous_block_last_def, invalid_jump_table_candidate, possible_target, relative_address, cmp_reg_to_reg, reg_def_use.def_used, cinf_ldr_add_pc, block_implies_block, contains_implausible_instr_seq, split_load_point, call_tls_get_addr, unresolved_block, split_load_operand, inferred_main_dispatch, gp_relative_operand, code_in_block_candidate_refined, reg_reg_arithmetic_operation_defs, litpool_symbolic_operand, data_access, init_symbol_minus_symbol_candidate_arm, plt_block, invalid, litpool_boundaries, segment_target_range, correlated_live_reg, arm_jump_table_block_instruction, simple_data_access_pattern, reg_def_use.live_var_at_block_end, reg_def_use.defined_in_block, block_last_instruction, flags_and_jump_pair, split_load_conflict, data_block_limit, last_value_reg_limit, reg_used_for, initialized_data_segment, __agg_subclause7, stack_def_use.live_var_at_prior_used, jump_table_start, unresolved_block_overlap, arch.extend_load, stack_def_use.def_used, init_ldr_add_pc, litpool_confidence, tls_desc_call, common_tail, stack_def_use.ref_in_block, arch.simple_data_load, reg_def_use.used_in_block, base_relative_jump, branch_to_calculated_pc_rel_addr, stack_def_use.live_var_def, wis_schedule_iter, jump_table_prelude, negative_block_heuristic, relocation_adjustment, compare_and_jump_indirect, reg_def_use.last_def_in_block, relative_jump_table_entry_candidate, discarded_split_load, __agg_single2, padding_block_limit, reg_def_use.return_block_end, plt_entry, stack_def_use.live_var_used

value_reg_address_before(EA:address, Reg:register, AddrValue:number, Steps:unsigned)

AddrValue represents the value of register Reg before EA. The value should be an address.

Uses: arch.reg_arithmetic_operation, code_in_block, jump_table_start, reg_def_use.def_used, reg_jump, step_limit, track_register

Recursive: data_object_conflict, labeled_data_candidate, boundary_sym_expr, symbolic_expr_symbol_minus_symbol, data_object, resolved_transfer, function_inference.function_entry, string_candidate, moved_data_label, labeled_ea, value_reg_address_before, code_pointer_in_data, moved_label_candidate, symbolic_operand_point, discarded_jump_table_entry, data_object_total_points, inferred_special_symbol, data_limit, next_data_limit, code_in_refined_block, data_access_limit, symbol_minus_symbol_from_relocation, +disconnected3, moved_displacement_candidate, best_func_symbol, main_function, data_object_point, data_limit_after_access, symbolic_data, string_candidate_refined, preferred_data_access, address_array, symbolic_expr, split_block, refined_block, moved_label, moved_pc_relative_candidate, +disconnected6, code_in_split_block, +disconnected2, after_address_in_data, address_array_aux, next_address_in_data, best_symexpr_symbol, data_object_candidate, symbolic_expr_attribute, +disconnected1, symbolic_operand_attribute, symbolic_operand, got_reference, block_needs_splitting_at, jump_table, label_conflict, symbol_minus_symbol, block_needs_merging, relative_jump_table_entry, base_relative_symbolic_operand, symbol_minus_symbol_candidate, discarded_data_object, symbol_score, inferred_main_function