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