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: litpool_symbolic_operand, __agg_single2, invalid, branch_to_calculated_pc_rel_addr, reg_used_for, data_block_limit, correlated_live_reg, inter_procedural_edge, value_reg_limit, no_value_reg_limit, init_symbol_minus_symbol_candidate_arm, start_function, jump_table_signed, stack_def_use.live_var_at_prior_used, arm_jump_table_block_start, code_in_block_candidate, wis_schedule_iter, split_load_operand, plt_block, base_relative_operand, next_function_entry_initial, stack_def_use.last_def_in_block, arch.reg_relative_load, data_in_code_propagate, must_fallthrough, jump_table_candidate, reg_has_got, block_instruction_next, negative_block_heuristic, relative_address_start, straight_line_def_used, data_in_code, reg_def_use.last_def_in_block, adjusts_stack_in_block, tls_desc_call, segment_target_range, next_block_in_byte_interval, next_type, discarded_block, block_points_proportional, __agg_single3, reg_def_use.live_var_used, instruction_memory_access_size, split_load_total_points, overlapping_instruction, value_reg_unsupported, jump_table_max, arm_jump_table_candidate, no_return_call, arm_jump_table_data_block, possible_target_from, arm_jump_table_skip_first_entry, self_contained_segment, call_target_has_other_fallthrough_inter, unresolved_block, indexed_pc_relative_load_relative, const_value_reg_used, block_last_instruction, __agg_single6, stack_def_use.live_var_at_block_end, straight_line_last_def, arch.simple_data_load, adrp_used, block, reg_def_use.live_var_at_block_end, reg_reg_arithmetic_operation_defs, jump_table_prelude, arm_jump_table_block_instruction, flags_and_jump_pair, plt_entry, simple_data_access_pattern, call_tls_get_addr, compare_and_jump_indirect_op_valid, block_points, reg_def_use.def_used, stack_def_use.live_var_used_in_block, arm_jump_table_data_block_limit, relative_address, split_load_candidate, data_block_candidate, base_relative_operation, value_reg_edge, block_total_points, compare_and_jump_immediate, compare_and_jump_indirect, def_used_for_address, split_load_point, fallthrough_over_padding, __agg_subclause6, split_load_conflict, got_relative_operand, reg_def_use.ambiguous_block_last_def, reg_def_use.block_last_def, known_block, may_fallthrough, relative_jump_table_entry_candidate, __agg_single10, reg_has_base_image, unresolved_interval_order, unresolved_interval, candidate_block_is_not_padding, inferred_main_dispatch, split_load_for_symbolization, stack_def_use.used_in_block, first_block_in_byte_interval, indefinite_litpool_ref, no_return_block, inferred_main_in_reg, incomplete_block, impossible_block, block_next, stack_base_reg_move, unlikely_have_symbolic_immediate, tls_get_addr, base_relative_jump, block_limit, padding_block_candidate, data_access, compare_and_jump_register, next_end, cinf_ldr_add_pc, block_candidate_boundaries, possible_target, block_candidate_dependency_edge, reg_def_use.live_var_at_prior_used, jump_table_candidate_refined, basic_target, stack_def_use.live_var_def, wis_prior, block_implies_block, block_boundaries, litpool_confidence, wis_has_prior, reg_def_use.return_block_end, symbol_minus_symbol_litpool_access_pattern, reg_def_use.flow_def, likely_fallthrough, stack_def_use.block_last_def, invalid_jump_table_candidate, cmp_defines, code_in_block_candidate_refined, hi_load_prop, wis_memo, overlap_with_litpool, resolved_reaches, reg_def_use.return_val_used, call_may_fallthrough_inter, function_inference.function_entry_initial, candidate_block_is_padding, __agg_subclause4, unresolved_block_overlap, padding_block_limit, stack_def_use.ref_in_block, init_ldr_add_pc, litpool_ref, discarded_split_load, value_reg, block_heuristic, reg_def_use.defined_in_block, initial_function_containing_return, reg_def_use.used_in_block, gp_relative_operand, stack_def_use.def_used, no_return_call_refined, jump_table_target, next_start, common_tail, symbolic_expr_from_relocation, tls_relative_operand_mips, block_overlap, contains_implausible_instr_seq, stack_def_use.defined_in_block, composite_data_access, contains_plausible_instr_seq, arm_jump_table_cmp_limit, relocation_adjustment, jump_table_start, relocation_adjustment_total, local_dynamic_tls_candidate, call_tls_get_addr_mips, stack_def_use.live_var_used, code_in_block, indexed_pc_relative_load, no_return_call_propagated, reg_def_use.ref_in_block, data_segment, is_padding, after_end, arm_jump_table_candidate_start, wis_schedule, nop_in_padding_candidate, reg_def_use.live_var_def, jump_table_element_access, split_load, __agg_subclause3, __agg_subclause2, reg_def_use.ambiguous_last_def_in_block, last_value_reg_limit, transition_block_limit, __agg_subclause7, arch.extend_load, initialized_data_segment, cmp_reg_to_reg, litpool_boundaries, reg_def_use.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: litpool_symbolic_operand, __agg_single2, invalid, branch_to_calculated_pc_rel_addr, reg_used_for, data_block_limit, correlated_live_reg, inter_procedural_edge, value_reg_limit, no_value_reg_limit, init_symbol_minus_symbol_candidate_arm, start_function, jump_table_signed, stack_def_use.live_var_at_prior_used, arm_jump_table_block_start, code_in_block_candidate, wis_schedule_iter, split_load_operand, plt_block, base_relative_operand, next_function_entry_initial, stack_def_use.last_def_in_block, arch.reg_relative_load, data_in_code_propagate, must_fallthrough, jump_table_candidate, reg_has_got, block_instruction_next, negative_block_heuristic, relative_address_start, straight_line_def_used, data_in_code, reg_def_use.last_def_in_block, adjusts_stack_in_block, tls_desc_call, segment_target_range, next_block_in_byte_interval, next_type, discarded_block, block_points_proportional, __agg_single3, reg_def_use.live_var_used, instruction_memory_access_size, split_load_total_points, overlapping_instruction, value_reg_unsupported, jump_table_max, arm_jump_table_candidate, no_return_call, arm_jump_table_data_block, possible_target_from, arm_jump_table_skip_first_entry, self_contained_segment, call_target_has_other_fallthrough_inter, unresolved_block, indexed_pc_relative_load_relative, const_value_reg_used, block_last_instruction, __agg_single6, stack_def_use.live_var_at_block_end, straight_line_last_def, arch.simple_data_load, adrp_used, block, reg_def_use.live_var_at_block_end, reg_reg_arithmetic_operation_defs, jump_table_prelude, arm_jump_table_block_instruction, flags_and_jump_pair, plt_entry, simple_data_access_pattern, call_tls_get_addr, compare_and_jump_indirect_op_valid, block_points, reg_def_use.def_used, stack_def_use.live_var_used_in_block, arm_jump_table_data_block_limit, relative_address, split_load_candidate, data_block_candidate, base_relative_operation, value_reg_edge, block_total_points, compare_and_jump_immediate, compare_and_jump_indirect, def_used_for_address, split_load_point, fallthrough_over_padding, __agg_subclause6, split_load_conflict, got_relative_operand, reg_def_use.ambiguous_block_last_def, reg_def_use.block_last_def, known_block, may_fallthrough, relative_jump_table_entry_candidate, __agg_single10, reg_has_base_image, unresolved_interval_order, unresolved_interval, candidate_block_is_not_padding, inferred_main_dispatch, split_load_for_symbolization, stack_def_use.used_in_block, first_block_in_byte_interval, indefinite_litpool_ref, no_return_block, inferred_main_in_reg, incomplete_block, impossible_block, block_next, stack_base_reg_move, unlikely_have_symbolic_immediate, tls_get_addr, base_relative_jump, block_limit, padding_block_candidate, data_access, compare_and_jump_register, next_end, cinf_ldr_add_pc, block_candidate_boundaries, possible_target, block_candidate_dependency_edge, reg_def_use.live_var_at_prior_used, jump_table_candidate_refined, basic_target, stack_def_use.live_var_def, wis_prior, block_implies_block, block_boundaries, litpool_confidence, wis_has_prior, reg_def_use.return_block_end, symbol_minus_symbol_litpool_access_pattern, reg_def_use.flow_def, likely_fallthrough, stack_def_use.block_last_def, invalid_jump_table_candidate, cmp_defines, code_in_block_candidate_refined, hi_load_prop, wis_memo, overlap_with_litpool, resolved_reaches, reg_def_use.return_val_used, call_may_fallthrough_inter, function_inference.function_entry_initial, candidate_block_is_padding, __agg_subclause4, unresolved_block_overlap, padding_block_limit, stack_def_use.ref_in_block, init_ldr_add_pc, litpool_ref, discarded_split_load, value_reg, block_heuristic, reg_def_use.defined_in_block, initial_function_containing_return, reg_def_use.used_in_block, gp_relative_operand, stack_def_use.def_used, no_return_call_refined, jump_table_target, next_start, common_tail, symbolic_expr_from_relocation, tls_relative_operand_mips, block_overlap, contains_implausible_instr_seq, stack_def_use.defined_in_block, composite_data_access, contains_plausible_instr_seq, arm_jump_table_cmp_limit, relocation_adjustment, jump_table_start, relocation_adjustment_total, local_dynamic_tls_candidate, call_tls_get_addr_mips, stack_def_use.live_var_used, code_in_block, indexed_pc_relative_load, no_return_call_propagated, reg_def_use.ref_in_block, data_segment, is_padding, after_end, arm_jump_table_candidate_start, wis_schedule, nop_in_padding_candidate, reg_def_use.live_var_def, jump_table_element_access, split_load, __agg_subclause3, __agg_subclause2, reg_def_use.ambiguous_last_def_in_block, last_value_reg_limit, transition_block_limit, __agg_subclause7, arch.extend_load, initialized_data_segment, cmp_reg_to_reg, litpool_boundaries, reg_def_use.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: litpool_symbolic_operand, __agg_single2, invalid, branch_to_calculated_pc_rel_addr, reg_used_for, data_block_limit, correlated_live_reg, inter_procedural_edge, value_reg_limit, no_value_reg_limit, init_symbol_minus_symbol_candidate_arm, start_function, jump_table_signed, stack_def_use.live_var_at_prior_used, arm_jump_table_block_start, code_in_block_candidate, wis_schedule_iter, split_load_operand, plt_block, base_relative_operand, next_function_entry_initial, stack_def_use.last_def_in_block, arch.reg_relative_load, data_in_code_propagate, must_fallthrough, jump_table_candidate, reg_has_got, block_instruction_next, negative_block_heuristic, relative_address_start, straight_line_def_used, data_in_code, reg_def_use.last_def_in_block, adjusts_stack_in_block, tls_desc_call, segment_target_range, next_block_in_byte_interval, next_type, discarded_block, block_points_proportional, __agg_single3, reg_def_use.live_var_used, instruction_memory_access_size, split_load_total_points, overlapping_instruction, value_reg_unsupported, jump_table_max, arm_jump_table_candidate, no_return_call, arm_jump_table_data_block, possible_target_from, arm_jump_table_skip_first_entry, self_contained_segment, call_target_has_other_fallthrough_inter, unresolved_block, indexed_pc_relative_load_relative, const_value_reg_used, block_last_instruction, __agg_single6, stack_def_use.live_var_at_block_end, straight_line_last_def, arch.simple_data_load, adrp_used, block, reg_def_use.live_var_at_block_end, reg_reg_arithmetic_operation_defs, jump_table_prelude, arm_jump_table_block_instruction, flags_and_jump_pair, plt_entry, simple_data_access_pattern, call_tls_get_addr, compare_and_jump_indirect_op_valid, block_points, reg_def_use.def_used, stack_def_use.live_var_used_in_block, arm_jump_table_data_block_limit, relative_address, split_load_candidate, data_block_candidate, base_relative_operation, value_reg_edge, block_total_points, compare_and_jump_immediate, compare_and_jump_indirect, def_used_for_address, split_load_point, fallthrough_over_padding, __agg_subclause6, split_load_conflict, got_relative_operand, reg_def_use.ambiguous_block_last_def, reg_def_use.block_last_def, known_block, may_fallthrough, relative_jump_table_entry_candidate, __agg_single10, reg_has_base_image, unresolved_interval_order, unresolved_interval, candidate_block_is_not_padding, inferred_main_dispatch, split_load_for_symbolization, stack_def_use.used_in_block, first_block_in_byte_interval, indefinite_litpool_ref, no_return_block, inferred_main_in_reg, incomplete_block, impossible_block, block_next, stack_base_reg_move, unlikely_have_symbolic_immediate, tls_get_addr, base_relative_jump, block_limit, padding_block_candidate, data_access, compare_and_jump_register, next_end, cinf_ldr_add_pc, block_candidate_boundaries, possible_target, block_candidate_dependency_edge, reg_def_use.live_var_at_prior_used, jump_table_candidate_refined, basic_target, stack_def_use.live_var_def, wis_prior, block_implies_block, block_boundaries, litpool_confidence, wis_has_prior, reg_def_use.return_block_end, symbol_minus_symbol_litpool_access_pattern, reg_def_use.flow_def, likely_fallthrough, stack_def_use.block_last_def, invalid_jump_table_candidate, cmp_defines, code_in_block_candidate_refined, hi_load_prop, wis_memo, overlap_with_litpool, resolved_reaches, reg_def_use.return_val_used, call_may_fallthrough_inter, function_inference.function_entry_initial, candidate_block_is_padding, __agg_subclause4, unresolved_block_overlap, padding_block_limit, stack_def_use.ref_in_block, init_ldr_add_pc, litpool_ref, discarded_split_load, value_reg, block_heuristic, reg_def_use.defined_in_block, initial_function_containing_return, reg_def_use.used_in_block, gp_relative_operand, stack_def_use.def_used, no_return_call_refined, jump_table_target, next_start, common_tail, symbolic_expr_from_relocation, tls_relative_operand_mips, block_overlap, contains_implausible_instr_seq, stack_def_use.defined_in_block, composite_data_access, contains_plausible_instr_seq, arm_jump_table_cmp_limit, relocation_adjustment, jump_table_start, relocation_adjustment_total, local_dynamic_tls_candidate, call_tls_get_addr_mips, stack_def_use.live_var_used, code_in_block, indexed_pc_relative_load, no_return_call_propagated, reg_def_use.ref_in_block, data_segment, is_padding, after_end, arm_jump_table_candidate_start, wis_schedule, nop_in_padding_candidate, reg_def_use.live_var_def, jump_table_element_access, split_load, __agg_subclause3, __agg_subclause2, reg_def_use.ambiguous_last_def_in_block, last_value_reg_limit, transition_block_limit, __agg_subclause7, arch.extend_load, initialized_data_segment, cmp_reg_to_reg, litpool_boundaries, reg_def_use.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: litpool_symbolic_operand, __agg_single2, invalid, branch_to_calculated_pc_rel_addr, reg_used_for, data_block_limit, correlated_live_reg, inter_procedural_edge, value_reg_limit, no_value_reg_limit, init_symbol_minus_symbol_candidate_arm, start_function, jump_table_signed, stack_def_use.live_var_at_prior_used, arm_jump_table_block_start, code_in_block_candidate, wis_schedule_iter, split_load_operand, plt_block, base_relative_operand, next_function_entry_initial, stack_def_use.last_def_in_block, arch.reg_relative_load, data_in_code_propagate, must_fallthrough, jump_table_candidate, reg_has_got, block_instruction_next, negative_block_heuristic, relative_address_start, straight_line_def_used, data_in_code, reg_def_use.last_def_in_block, adjusts_stack_in_block, tls_desc_call, segment_target_range, next_block_in_byte_interval, next_type, discarded_block, block_points_proportional, __agg_single3, reg_def_use.live_var_used, instruction_memory_access_size, split_load_total_points, overlapping_instruction, value_reg_unsupported, jump_table_max, arm_jump_table_candidate, no_return_call, arm_jump_table_data_block, possible_target_from, arm_jump_table_skip_first_entry, self_contained_segment, call_target_has_other_fallthrough_inter, unresolved_block, indexed_pc_relative_load_relative, const_value_reg_used, block_last_instruction, __agg_single6, stack_def_use.live_var_at_block_end, straight_line_last_def, arch.simple_data_load, adrp_used, block, reg_def_use.live_var_at_block_end, reg_reg_arithmetic_operation_defs, jump_table_prelude, arm_jump_table_block_instruction, flags_and_jump_pair, plt_entry, simple_data_access_pattern, call_tls_get_addr, compare_and_jump_indirect_op_valid, block_points, reg_def_use.def_used, stack_def_use.live_var_used_in_block, arm_jump_table_data_block_limit, relative_address, split_load_candidate, data_block_candidate, base_relative_operation, value_reg_edge, block_total_points, compare_and_jump_immediate, compare_and_jump_indirect, def_used_for_address, split_load_point, fallthrough_over_padding, __agg_subclause6, split_load_conflict, got_relative_operand, reg_def_use.ambiguous_block_last_def, reg_def_use.block_last_def, known_block, may_fallthrough, relative_jump_table_entry_candidate, __agg_single10, reg_has_base_image, unresolved_interval_order, unresolved_interval, candidate_block_is_not_padding, inferred_main_dispatch, split_load_for_symbolization, stack_def_use.used_in_block, first_block_in_byte_interval, indefinite_litpool_ref, no_return_block, inferred_main_in_reg, incomplete_block, impossible_block, block_next, stack_base_reg_move, unlikely_have_symbolic_immediate, tls_get_addr, base_relative_jump, block_limit, padding_block_candidate, data_access, compare_and_jump_register, next_end, cinf_ldr_add_pc, block_candidate_boundaries, possible_target, block_candidate_dependency_edge, reg_def_use.live_var_at_prior_used, jump_table_candidate_refined, basic_target, stack_def_use.live_var_def, wis_prior, block_implies_block, block_boundaries, litpool_confidence, wis_has_prior, reg_def_use.return_block_end, symbol_minus_symbol_litpool_access_pattern, reg_def_use.flow_def, likely_fallthrough, stack_def_use.block_last_def, invalid_jump_table_candidate, cmp_defines, code_in_block_candidate_refined, hi_load_prop, wis_memo, overlap_with_litpool, resolved_reaches, reg_def_use.return_val_used, call_may_fallthrough_inter, function_inference.function_entry_initial, candidate_block_is_padding, __agg_subclause4, unresolved_block_overlap, padding_block_limit, stack_def_use.ref_in_block, init_ldr_add_pc, litpool_ref, discarded_split_load, value_reg, block_heuristic, reg_def_use.defined_in_block, initial_function_containing_return, reg_def_use.used_in_block, gp_relative_operand, stack_def_use.def_used, no_return_call_refined, jump_table_target, next_start, common_tail, symbolic_expr_from_relocation, tls_relative_operand_mips, block_overlap, contains_implausible_instr_seq, stack_def_use.defined_in_block, composite_data_access, contains_plausible_instr_seq, arm_jump_table_cmp_limit, relocation_adjustment, jump_table_start, relocation_adjustment_total, local_dynamic_tls_candidate, call_tls_get_addr_mips, stack_def_use.live_var_used, code_in_block, indexed_pc_relative_load, no_return_call_propagated, reg_def_use.ref_in_block, data_segment, is_padding, after_end, arm_jump_table_candidate_start, wis_schedule, nop_in_padding_candidate, reg_def_use.live_var_def, jump_table_element_access, split_load, __agg_subclause3, __agg_subclause2, reg_def_use.ambiguous_last_def_in_block, last_value_reg_limit, transition_block_limit, __agg_subclause7, arch.extend_load, initialized_data_segment, cmp_reg_to_reg, litpool_boundaries, reg_def_use.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: subsequent_string_candidate, preferred_data_access, string_candidate_refined, inferred_main_function, discarded_data_object, +disconnected6, resolved_transfer, code_in_refined_block, inferred_special_symbol, relative_jump_table_entry, symbolic_operand_attribute, symbol_score, inferred_symbol_mips, code_in_split_block, after_address_in_data, moved_data_label, moved_label, code_pointer_in_data, data_limit_after_access, labeled_ea, data_object_point, moved_label_candidate, block_needs_merging, moved_displacement_candidate, symbolic_expr_symbol_minus_symbol, refined_block, main_function, jump_table, data_object_conflict, +disconnected1, symbol_minus_symbol, best_func_symbol, best_symexpr_symbol, symbolic_operand_point, discarded_jump_table_entry, label_conflict, address_array, +disconnected2, value_reg_address_before, symbolic_expr_attribute, string_candidate, address_array_aux, data_access_limit, split_block, symbolic_expr, inferred_symbol, data_object_candidate, function_inference.function_entry, labeled_data_candidate, symbolic_data, data_limit, symbolic_operand, block_needs_splitting_at, boundary_sym_expr, moved_pc_relative_candidate, +disconnected4, got_reference, next_address_in_data, symbol_minus_symbol_from_relocation, next_data_limit, data_object, symbol_minus_symbol_candidate, data_object_total_points