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

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

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

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

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