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

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

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

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

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: symbol_minus_symbol, value_reg_address_before, symbolic_operand_point, label_conflict, labeled_ea, moved_data_label, best_symexpr_symbol, symbolic_expr, inferred_special_symbol, address_array, moved_displacement_candidate, relative_jump_table_entry, block_needs_splitting_at, code_in_refined_block, symbolic_data, got_reference, +disconnected4, symbolic_operand_attribute, symbolic_expr_attribute, inferred_main_function, data_limit_after_access, resolved_transfer, +disconnected6, next_address_in_data, address_array_aux, next_data_limit, inferred_symbol, data_limit, data_object_candidate, data_access_limit, preferred_data_access, data_object_point, code_pointer_in_data, data_object_total_points, block_needs_merging, best_func_symbol, inferred_symbol_mips, moved_pc_relative_candidate, main_function, symbolic_operand, after_address_in_data, jump_table, data_object, symbol_minus_symbol_from_relocation, discarded_jump_table_entry, string_candidate_refined, +disconnected7, split_block, symbol_score, string_candidate, boundary_sym_expr, discarded_data_object, moved_label_candidate, moved_label, +disconnected2, data_object_conflict, refined_block, symbolic_expr_symbol_minus_symbol, symbol_minus_symbol_candidate, function_inference.function_entry, subsequent_string_candidate, code_in_split_block, labeled_data_candidate, elf_header_operand