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

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

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

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

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