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

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

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

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

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