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

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

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

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

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