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: stack_base_reg_move, jump_table_candidate, padding_block_limit, adrp_used, inferred_main_dispatch, block_next, wis_schedule, base_relative_operation, reg_def_use.live_var_used, stack_def_use.last_def_in_block, correlated_live_reg, no_return_call_refined, inter_procedural_edge, next_end, compare_and_jump_immediate, relocation_adjustment, cinf_ldr_add_pc, unresolved_interval, possible_target_from, block_candidate_dependency_edge, compare_and_jump_indirect, cmp_defines, local_dynamic_tls_candidate, basic_target, block_points, wis_has_prior, contains_implausible_instr_seq, stack_def_use.defined_in_block, known_block, common_tail, call_tls_get_addr, __agg_subclause6, overlapping_instruction, may_fallthrough, jump_table_target, impossible_block, block_last_instruction, unresolved_block, reg_has_got, reg_reg_arithmetic_operation_defs, __agg_subclause7, next_type, data_block_limit, reg_def_use.flow_def, data_segment, split_load_total_points, call_target_has_other_fallthrough_inter, next_function_entry_initial, got_relative_operand, discarded_split_load, reg_def_use.def_used, reg_has_base_image, gp_relative_operand, __agg_single6, must_fallthrough, candidate_block_is_not_padding, code_in_block_candidate, cmp_reg_to_reg, next_block_in_byte_interval, stack_def_use.live_var_used, segment_target_range, reg_def_use.return_val_used, jump_table_max, composite_data_access, plt_block, block_limit, reg_used_for, split_load_candidate, adjusts_stack_in_block, const_value_reg_used, is_padding, jump_table_element_access, reg_def_use.ambiguous_last_def_in_block, reg_def_use.ref_in_block, init_symbol_minus_symbol_candidate_arm, call_may_fallthrough_inter, reg_def_use.live_var_at_prior_used, reg_def_use.used, negative_block_heuristic, block_heuristic, split_load, reg_def_use.return_block_end, straight_line_def_used, start_function, split_load_conflict, symbol_minus_symbol_litpool_access_pattern, invalid, function_inference.function_entry_initial, compare_and_jump_register, hi_load_prop, __agg_subclause3, wis_prior, value_reg_unsupported, jump_table_prelude, wis_schedule_iter, init_ldr_add_pc, discarded_block, likely_fallthrough, initialized_data_segment, __agg_single3, call_tls_get_addr_mips, data_in_code, stack_def_use.def_used, data_in_code_propagate, compare_and_jump_indirect_op_valid, branch_to_calculated_pc_rel_addr, reg_def_use.last_def_in_block, data_access, split_load_point, unlikely_have_symbolic_immediate, stack_def_use.used_in_block, arch.extend_load, relative_address, block_boundaries, arm_jump_table_data_block, stack_def_use.ref_in_block, self_contained_segment, inferred_main_in_reg, code_in_block, stack_def_use.block_last_def, relative_jump_table_entry_candidate, indexed_pc_relative_load_relative, litpool_boundaries, arm_jump_table_candidate_start, code_in_block_candidate_refined, fallthrough_over_padding, jump_table_candidate_refined, reg_def_use.used_in_block, no_value_reg_limit, reg_def_use.ambiguous_block_last_def, padding_block_candidate, resolved_reaches, __agg_single2, relocation_adjustment_total, invalid_jump_table_candidate, no_return_call, nop_in_padding_candidate, arm_jump_table_cmp_limit, arch.simple_data_load, initial_function_containing_return, reg_def_use.live_var_at_block_end, base_relative_jump, reg_def_use.block_last_def, tls_relative_operand_mips, simple_data_access_pattern, __agg_single10, arch.reg_relative_load, stack_def_use.live_var_def, block_total_points, overlap_with_litpool, straight_line_last_def, arm_jump_table_skip_first_entry, arm_jump_table_data_block_limit, __agg_subclause2, after_end, value_reg_limit, flags_and_jump_pair, instruction_memory_access_size, data_block_candidate, block_overlap, next_start, unresolved_interval_order, value_reg, indexed_pc_relative_load, split_load_operand, unresolved_block_overlap, no_return_call_propagated, __agg_subclause4, split_load_for_symbolization, litpool_ref, tls_get_addr, block_implies_block, wis_memo, jump_table_start, stack_def_use.live_var_at_block_end, contains_plausible_instr_seq, transition_block_limit, litpool_symbolic_operand, arm_jump_table_block_start, tls_desc_call, stack_def_use.live_var_at_prior_used, plt_entry, relative_address_start, value_reg_edge, block, reg_def_use.defined_in_block, block_points_proportional, indefinite_litpool_ref, litpool_confidence, jump_table_signed, arm_jump_table_candidate, incomplete_block, symbolic_expr_from_relocation, block_instruction_next, def_used_for_address, block_candidate_boundaries, reg_def_use.live_var_def, no_return_block, base_relative_operand, arm_jump_table_block_instruction, possible_target, candidate_block_is_padding, first_block_in_byte_interval, stack_def_use.live_var_used_in_block, last_value_reg_limit

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: stack_base_reg_move, jump_table_candidate, padding_block_limit, adrp_used, inferred_main_dispatch, block_next, wis_schedule, base_relative_operation, reg_def_use.live_var_used, stack_def_use.last_def_in_block, correlated_live_reg, no_return_call_refined, inter_procedural_edge, next_end, compare_and_jump_immediate, relocation_adjustment, cinf_ldr_add_pc, unresolved_interval, possible_target_from, block_candidate_dependency_edge, compare_and_jump_indirect, cmp_defines, local_dynamic_tls_candidate, basic_target, block_points, wis_has_prior, contains_implausible_instr_seq, stack_def_use.defined_in_block, known_block, common_tail, call_tls_get_addr, __agg_subclause6, overlapping_instruction, may_fallthrough, jump_table_target, impossible_block, block_last_instruction, unresolved_block, reg_has_got, reg_reg_arithmetic_operation_defs, __agg_subclause7, next_type, data_block_limit, reg_def_use.flow_def, data_segment, split_load_total_points, call_target_has_other_fallthrough_inter, next_function_entry_initial, got_relative_operand, discarded_split_load, reg_def_use.def_used, reg_has_base_image, gp_relative_operand, __agg_single6, must_fallthrough, candidate_block_is_not_padding, code_in_block_candidate, cmp_reg_to_reg, next_block_in_byte_interval, stack_def_use.live_var_used, segment_target_range, reg_def_use.return_val_used, jump_table_max, composite_data_access, plt_block, block_limit, reg_used_for, split_load_candidate, adjusts_stack_in_block, const_value_reg_used, is_padding, jump_table_element_access, reg_def_use.ambiguous_last_def_in_block, reg_def_use.ref_in_block, init_symbol_minus_symbol_candidate_arm, call_may_fallthrough_inter, reg_def_use.live_var_at_prior_used, reg_def_use.used, negative_block_heuristic, block_heuristic, split_load, reg_def_use.return_block_end, straight_line_def_used, start_function, split_load_conflict, symbol_minus_symbol_litpool_access_pattern, invalid, function_inference.function_entry_initial, compare_and_jump_register, hi_load_prop, __agg_subclause3, wis_prior, value_reg_unsupported, jump_table_prelude, wis_schedule_iter, init_ldr_add_pc, discarded_block, likely_fallthrough, initialized_data_segment, __agg_single3, call_tls_get_addr_mips, data_in_code, stack_def_use.def_used, data_in_code_propagate, compare_and_jump_indirect_op_valid, branch_to_calculated_pc_rel_addr, reg_def_use.last_def_in_block, data_access, split_load_point, unlikely_have_symbolic_immediate, stack_def_use.used_in_block, arch.extend_load, relative_address, block_boundaries, arm_jump_table_data_block, stack_def_use.ref_in_block, self_contained_segment, inferred_main_in_reg, code_in_block, stack_def_use.block_last_def, relative_jump_table_entry_candidate, indexed_pc_relative_load_relative, litpool_boundaries, arm_jump_table_candidate_start, code_in_block_candidate_refined, fallthrough_over_padding, jump_table_candidate_refined, reg_def_use.used_in_block, no_value_reg_limit, reg_def_use.ambiguous_block_last_def, padding_block_candidate, resolved_reaches, __agg_single2, relocation_adjustment_total, invalid_jump_table_candidate, no_return_call, nop_in_padding_candidate, arm_jump_table_cmp_limit, arch.simple_data_load, initial_function_containing_return, reg_def_use.live_var_at_block_end, base_relative_jump, reg_def_use.block_last_def, tls_relative_operand_mips, simple_data_access_pattern, __agg_single10, arch.reg_relative_load, stack_def_use.live_var_def, block_total_points, overlap_with_litpool, straight_line_last_def, arm_jump_table_skip_first_entry, arm_jump_table_data_block_limit, __agg_subclause2, after_end, value_reg_limit, flags_and_jump_pair, instruction_memory_access_size, data_block_candidate, block_overlap, next_start, unresolved_interval_order, value_reg, indexed_pc_relative_load, split_load_operand, unresolved_block_overlap, no_return_call_propagated, __agg_subclause4, split_load_for_symbolization, litpool_ref, tls_get_addr, block_implies_block, wis_memo, jump_table_start, stack_def_use.live_var_at_block_end, contains_plausible_instr_seq, transition_block_limit, litpool_symbolic_operand, arm_jump_table_block_start, tls_desc_call, stack_def_use.live_var_at_prior_used, plt_entry, relative_address_start, value_reg_edge, block, reg_def_use.defined_in_block, block_points_proportional, indefinite_litpool_ref, litpool_confidence, jump_table_signed, arm_jump_table_candidate, incomplete_block, symbolic_expr_from_relocation, block_instruction_next, def_used_for_address, block_candidate_boundaries, reg_def_use.live_var_def, no_return_block, base_relative_operand, arm_jump_table_block_instruction, possible_target, candidate_block_is_padding, first_block_in_byte_interval, stack_def_use.live_var_used_in_block, last_value_reg_limit

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: stack_base_reg_move, jump_table_candidate, padding_block_limit, adrp_used, inferred_main_dispatch, block_next, wis_schedule, base_relative_operation, reg_def_use.live_var_used, stack_def_use.last_def_in_block, correlated_live_reg, no_return_call_refined, inter_procedural_edge, next_end, compare_and_jump_immediate, relocation_adjustment, cinf_ldr_add_pc, unresolved_interval, possible_target_from, block_candidate_dependency_edge, compare_and_jump_indirect, cmp_defines, local_dynamic_tls_candidate, basic_target, block_points, wis_has_prior, contains_implausible_instr_seq, stack_def_use.defined_in_block, known_block, common_tail, call_tls_get_addr, __agg_subclause6, overlapping_instruction, may_fallthrough, jump_table_target, impossible_block, block_last_instruction, unresolved_block, reg_has_got, reg_reg_arithmetic_operation_defs, __agg_subclause7, next_type, data_block_limit, reg_def_use.flow_def, data_segment, split_load_total_points, call_target_has_other_fallthrough_inter, next_function_entry_initial, got_relative_operand, discarded_split_load, reg_def_use.def_used, reg_has_base_image, gp_relative_operand, __agg_single6, must_fallthrough, candidate_block_is_not_padding, code_in_block_candidate, cmp_reg_to_reg, next_block_in_byte_interval, stack_def_use.live_var_used, segment_target_range, reg_def_use.return_val_used, jump_table_max, composite_data_access, plt_block, block_limit, reg_used_for, split_load_candidate, adjusts_stack_in_block, const_value_reg_used, is_padding, jump_table_element_access, reg_def_use.ambiguous_last_def_in_block, reg_def_use.ref_in_block, init_symbol_minus_symbol_candidate_arm, call_may_fallthrough_inter, reg_def_use.live_var_at_prior_used, reg_def_use.used, negative_block_heuristic, block_heuristic, split_load, reg_def_use.return_block_end, straight_line_def_used, start_function, split_load_conflict, symbol_minus_symbol_litpool_access_pattern, invalid, function_inference.function_entry_initial, compare_and_jump_register, hi_load_prop, __agg_subclause3, wis_prior, value_reg_unsupported, jump_table_prelude, wis_schedule_iter, init_ldr_add_pc, discarded_block, likely_fallthrough, initialized_data_segment, __agg_single3, call_tls_get_addr_mips, data_in_code, stack_def_use.def_used, data_in_code_propagate, compare_and_jump_indirect_op_valid, branch_to_calculated_pc_rel_addr, reg_def_use.last_def_in_block, data_access, split_load_point, unlikely_have_symbolic_immediate, stack_def_use.used_in_block, arch.extend_load, relative_address, block_boundaries, arm_jump_table_data_block, stack_def_use.ref_in_block, self_contained_segment, inferred_main_in_reg, code_in_block, stack_def_use.block_last_def, relative_jump_table_entry_candidate, indexed_pc_relative_load_relative, litpool_boundaries, arm_jump_table_candidate_start, code_in_block_candidate_refined, fallthrough_over_padding, jump_table_candidate_refined, reg_def_use.used_in_block, no_value_reg_limit, reg_def_use.ambiguous_block_last_def, padding_block_candidate, resolved_reaches, __agg_single2, relocation_adjustment_total, invalid_jump_table_candidate, no_return_call, nop_in_padding_candidate, arm_jump_table_cmp_limit, arch.simple_data_load, initial_function_containing_return, reg_def_use.live_var_at_block_end, base_relative_jump, reg_def_use.block_last_def, tls_relative_operand_mips, simple_data_access_pattern, __agg_single10, arch.reg_relative_load, stack_def_use.live_var_def, block_total_points, overlap_with_litpool, straight_line_last_def, arm_jump_table_skip_first_entry, arm_jump_table_data_block_limit, __agg_subclause2, after_end, value_reg_limit, flags_and_jump_pair, instruction_memory_access_size, data_block_candidate, block_overlap, next_start, unresolved_interval_order, value_reg, indexed_pc_relative_load, split_load_operand, unresolved_block_overlap, no_return_call_propagated, __agg_subclause4, split_load_for_symbolization, litpool_ref, tls_get_addr, block_implies_block, wis_memo, jump_table_start, stack_def_use.live_var_at_block_end, contains_plausible_instr_seq, transition_block_limit, litpool_symbolic_operand, arm_jump_table_block_start, tls_desc_call, stack_def_use.live_var_at_prior_used, plt_entry, relative_address_start, value_reg_edge, block, reg_def_use.defined_in_block, block_points_proportional, indefinite_litpool_ref, litpool_confidence, jump_table_signed, arm_jump_table_candidate, incomplete_block, symbolic_expr_from_relocation, block_instruction_next, def_used_for_address, block_candidate_boundaries, reg_def_use.live_var_def, no_return_block, base_relative_operand, arm_jump_table_block_instruction, possible_target, candidate_block_is_padding, first_block_in_byte_interval, stack_def_use.live_var_used_in_block, last_value_reg_limit

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: stack_base_reg_move, jump_table_candidate, padding_block_limit, adrp_used, inferred_main_dispatch, block_next, wis_schedule, base_relative_operation, reg_def_use.live_var_used, stack_def_use.last_def_in_block, correlated_live_reg, no_return_call_refined, inter_procedural_edge, next_end, compare_and_jump_immediate, relocation_adjustment, cinf_ldr_add_pc, unresolved_interval, possible_target_from, block_candidate_dependency_edge, compare_and_jump_indirect, cmp_defines, local_dynamic_tls_candidate, basic_target, block_points, wis_has_prior, contains_implausible_instr_seq, stack_def_use.defined_in_block, known_block, common_tail, call_tls_get_addr, __agg_subclause6, overlapping_instruction, may_fallthrough, jump_table_target, impossible_block, block_last_instruction, unresolved_block, reg_has_got, reg_reg_arithmetic_operation_defs, __agg_subclause7, next_type, data_block_limit, reg_def_use.flow_def, data_segment, split_load_total_points, call_target_has_other_fallthrough_inter, next_function_entry_initial, got_relative_operand, discarded_split_load, reg_def_use.def_used, reg_has_base_image, gp_relative_operand, __agg_single6, must_fallthrough, candidate_block_is_not_padding, code_in_block_candidate, cmp_reg_to_reg, next_block_in_byte_interval, stack_def_use.live_var_used, segment_target_range, reg_def_use.return_val_used, jump_table_max, composite_data_access, plt_block, block_limit, reg_used_for, split_load_candidate, adjusts_stack_in_block, const_value_reg_used, is_padding, jump_table_element_access, reg_def_use.ambiguous_last_def_in_block, reg_def_use.ref_in_block, init_symbol_minus_symbol_candidate_arm, call_may_fallthrough_inter, reg_def_use.live_var_at_prior_used, reg_def_use.used, negative_block_heuristic, block_heuristic, split_load, reg_def_use.return_block_end, straight_line_def_used, start_function, split_load_conflict, symbol_minus_symbol_litpool_access_pattern, invalid, function_inference.function_entry_initial, compare_and_jump_register, hi_load_prop, __agg_subclause3, wis_prior, value_reg_unsupported, jump_table_prelude, wis_schedule_iter, init_ldr_add_pc, discarded_block, likely_fallthrough, initialized_data_segment, __agg_single3, call_tls_get_addr_mips, data_in_code, stack_def_use.def_used, data_in_code_propagate, compare_and_jump_indirect_op_valid, branch_to_calculated_pc_rel_addr, reg_def_use.last_def_in_block, data_access, split_load_point, unlikely_have_symbolic_immediate, stack_def_use.used_in_block, arch.extend_load, relative_address, block_boundaries, arm_jump_table_data_block, stack_def_use.ref_in_block, self_contained_segment, inferred_main_in_reg, code_in_block, stack_def_use.block_last_def, relative_jump_table_entry_candidate, indexed_pc_relative_load_relative, litpool_boundaries, arm_jump_table_candidate_start, code_in_block_candidate_refined, fallthrough_over_padding, jump_table_candidate_refined, reg_def_use.used_in_block, no_value_reg_limit, reg_def_use.ambiguous_block_last_def, padding_block_candidate, resolved_reaches, __agg_single2, relocation_adjustment_total, invalid_jump_table_candidate, no_return_call, nop_in_padding_candidate, arm_jump_table_cmp_limit, arch.simple_data_load, initial_function_containing_return, reg_def_use.live_var_at_block_end, base_relative_jump, reg_def_use.block_last_def, tls_relative_operand_mips, simple_data_access_pattern, __agg_single10, arch.reg_relative_load, stack_def_use.live_var_def, block_total_points, overlap_with_litpool, straight_line_last_def, arm_jump_table_skip_first_entry, arm_jump_table_data_block_limit, __agg_subclause2, after_end, value_reg_limit, flags_and_jump_pair, instruction_memory_access_size, data_block_candidate, block_overlap, next_start, unresolved_interval_order, value_reg, indexed_pc_relative_load, split_load_operand, unresolved_block_overlap, no_return_call_propagated, __agg_subclause4, split_load_for_symbolization, litpool_ref, tls_get_addr, block_implies_block, wis_memo, jump_table_start, stack_def_use.live_var_at_block_end, contains_plausible_instr_seq, transition_block_limit, litpool_symbolic_operand, arm_jump_table_block_start, tls_desc_call, stack_def_use.live_var_at_prior_used, plt_entry, relative_address_start, value_reg_edge, block, reg_def_use.defined_in_block, block_points_proportional, indefinite_litpool_ref, litpool_confidence, jump_table_signed, arm_jump_table_candidate, incomplete_block, symbolic_expr_from_relocation, block_instruction_next, def_used_for_address, block_candidate_boundaries, reg_def_use.live_var_def, no_return_block, base_relative_operand, arm_jump_table_block_instruction, possible_target, candidate_block_is_padding, first_block_in_byte_interval, stack_def_use.live_var_used_in_block, last_value_reg_limit

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: subsequent_string_candidate, labeled_data_candidate, function_inference.function_entry, symbolic_operand, symbol_minus_symbol_candidate, address_array_aux, data_object_conflict, boundary_sym_expr, data_limit, data_object_candidate, data_object_point, moved_pc_relative_candidate, moved_displacement_candidate, next_data_limit, data_object_total_points, moved_label, resolved_transfer, jump_table, preferred_data_access, string_candidate, code_in_refined_block, label_conflict, +disconnected4, moved_data_label, symbolic_operand_point, +disconnected6, next_address_in_data, refined_block, value_reg_address_before, symbolic_data, symbolic_expr, +disconnected2, main_function, symbol_score, symbolic_expr_symbol_minus_symbol, symbol_minus_symbol, +disconnected1, moved_label_candidate, discarded_jump_table_entry, symbolic_operand_attribute, block_needs_splitting_at, relative_jump_table_entry, inferred_symbol, address_array, best_symexpr_symbol, symbol_minus_symbol_from_relocation, discarded_data_object, symbolic_expr_attribute, code_in_split_block, split_block, string_candidate_refined, best_func_symbol, after_address_in_data, inferred_main_function, inferred_symbol_mips, got_reference, data_limit_after_access, data_access_limit, block_needs_merging, labeled_ea, data_object, code_pointer_in_data, inferred_special_symbol