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

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

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

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

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