643 lines
22 KiB
Rust
643 lines
22 KiB
Rust
import tstate::ann::*;
|
|
import aux::*;
|
|
import bitvectors::{bit_num, seq_preconds, seq_postconds,
|
|
intersect_states,
|
|
relax_precond_block, gen};
|
|
import tritv::*;
|
|
|
|
import pat_util::*;
|
|
import syntax::ast::*;
|
|
import syntax::ast_util::*;
|
|
import syntax::visit;
|
|
import util::common::{log_expr, field_exprs,
|
|
has_nonlocal_exits, log_stmt};
|
|
import syntax::codemap::span;
|
|
import driver::session::session;
|
|
import std::map::hashmap;
|
|
|
|
fn find_pre_post_mod(_m: _mod) -> _mod {
|
|
#debug("implement find_pre_post_mod!");
|
|
fail;
|
|
}
|
|
|
|
fn find_pre_post_native_mod(_m: native_mod) -> native_mod {
|
|
#debug("implement find_pre_post_native_mod");
|
|
fail;
|
|
}
|
|
|
|
fn find_pre_post_method(ccx: crate_ctxt, m: @method) {
|
|
assert (ccx.fm.contains_key(m.id));
|
|
let fcx: fn_ctxt =
|
|
{enclosing: ccx.fm.get(m.id),
|
|
id: m.id,
|
|
name: m.ident,
|
|
ccx: ccx};
|
|
find_pre_post_fn(fcx, m.body);
|
|
}
|
|
|
|
fn find_pre_post_item(ccx: crate_ctxt, i: item) {
|
|
alt i.node {
|
|
item_const(_, e) {
|
|
// do nothing -- item_consts don't refer to local vars
|
|
}
|
|
item_fn(_, _, body) {
|
|
assert (ccx.fm.contains_key(i.id));
|
|
let fcx =
|
|
{enclosing: ccx.fm.get(i.id), id: i.id, name: i.ident, ccx: ccx};
|
|
find_pre_post_fn(fcx, body);
|
|
}
|
|
item_mod(m) { find_pre_post_mod(m); }
|
|
item_native_mod(nm) { find_pre_post_native_mod(nm); }
|
|
item_ty(*) | item_enum(*) | item_iface(*) { ret; }
|
|
item_res(_, _, body, dtor_id, _, _) {
|
|
let fcx =
|
|
{enclosing: ccx.fm.get(dtor_id),
|
|
id: dtor_id,
|
|
name: i.ident,
|
|
ccx: ccx};
|
|
find_pre_post_fn(fcx, body);
|
|
}
|
|
item_class(*) {
|
|
fail "find_pre_post_item: shouldn't be called on item_class";
|
|
}
|
|
item_impl(_, _, _, _, ms) {
|
|
for ms.each {|m| find_pre_post_method(ccx, m); }
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/* Finds the pre and postcondition for each expr in <args>;
|
|
sets the precondition in a to be the result of combining
|
|
the preconditions for <args>, and the postcondition in a to
|
|
be the union of all postconditions for <args> */
|
|
fn find_pre_post_exprs(fcx: fn_ctxt, args: [@expr], id: node_id) {
|
|
if vec::len::<@expr>(args) > 0u {
|
|
#debug("find_pre_post_exprs: oper =");
|
|
log_expr(*args[0]);
|
|
}
|
|
fn do_one(fcx: fn_ctxt, e: @expr) { find_pre_post_expr(fcx, e); }
|
|
for args.each {|e| do_one(fcx, e); }
|
|
|
|
fn get_pp(ccx: crate_ctxt, &&e: @expr) -> pre_and_post {
|
|
ret expr_pp(ccx, e);
|
|
}
|
|
let pps = vec::map(args, bind get_pp(fcx.ccx, _));
|
|
|
|
set_pre_and_post(fcx.ccx, id, seq_preconds(fcx, pps),
|
|
seq_postconds(fcx, vec::map(pps, get_post)));
|
|
}
|
|
|
|
fn find_pre_post_loop(fcx: fn_ctxt, index: @expr, body: blk, id: node_id) {
|
|
find_pre_post_expr(fcx, index);
|
|
find_pre_post_block(fcx, body);
|
|
|
|
let loop_precond =
|
|
seq_preconds(fcx, [expr_pp(fcx.ccx, index), block_pp(fcx.ccx, body)]);
|
|
let loop_postcond =
|
|
intersect_states(expr_postcond(fcx.ccx, index),
|
|
block_postcond(fcx.ccx, body));
|
|
copy_pre_post_(fcx.ccx, id, loop_precond, loop_postcond);
|
|
}
|
|
|
|
// Generates a pre/post assuming that a is the
|
|
// annotation for an if-expression with consequent conseq
|
|
// and alternative maybe_alt
|
|
fn join_then_else(fcx: fn_ctxt, antec: @expr, conseq: blk,
|
|
maybe_alt: option<@expr>, id: node_id, chck: if_ty) {
|
|
find_pre_post_expr(fcx, antec);
|
|
find_pre_post_block(fcx, conseq);
|
|
alt maybe_alt {
|
|
none {
|
|
alt chck {
|
|
if_check {
|
|
let c: sp_constr = expr_to_constr(fcx.ccx.tcx, antec);
|
|
gen(fcx, antec.id, c.node);
|
|
}
|
|
_ { }
|
|
}
|
|
|
|
let precond_res =
|
|
seq_preconds(fcx,
|
|
[expr_pp(fcx.ccx, antec),
|
|
block_pp(fcx.ccx, conseq)]);
|
|
set_pre_and_post(fcx.ccx, id, precond_res,
|
|
expr_poststate(fcx.ccx, antec));
|
|
}
|
|
some(altern) {
|
|
/*
|
|
if check = if_check, then
|
|
be sure that the predicate implied by antec
|
|
is *not* true in the alternative
|
|
*/
|
|
find_pre_post_expr(fcx, altern);
|
|
let precond_false_case =
|
|
seq_preconds(fcx,
|
|
[expr_pp(fcx.ccx, antec), expr_pp(fcx.ccx, altern)]);
|
|
let postcond_false_case =
|
|
seq_postconds(fcx,
|
|
[expr_postcond(fcx.ccx, antec),
|
|
expr_postcond(fcx.ccx, altern)]);
|
|
|
|
/* Be sure to set the bit for the check condition here,
|
|
so that it's *not* set in the alternative. */
|
|
alt chck {
|
|
if_check {
|
|
let c: sp_constr = expr_to_constr(fcx.ccx.tcx, antec);
|
|
gen(fcx, antec.id, c.node);
|
|
}
|
|
_ { }
|
|
}
|
|
let precond_true_case =
|
|
seq_preconds(fcx,
|
|
[expr_pp(fcx.ccx, antec),
|
|
block_pp(fcx.ccx, conseq)]);
|
|
let postcond_true_case =
|
|
seq_postconds(fcx,
|
|
[expr_postcond(fcx.ccx, antec),
|
|
block_postcond(fcx.ccx, conseq)]);
|
|
|
|
let precond_res =
|
|
seq_postconds(fcx, [precond_true_case, precond_false_case]);
|
|
let postcond_res =
|
|
intersect_states(postcond_true_case, postcond_false_case);
|
|
set_pre_and_post(fcx.ccx, id, precond_res, postcond_res);
|
|
}
|
|
}
|
|
}
|
|
|
|
fn gen_if_local(fcx: fn_ctxt, lhs: @expr, rhs: @expr, larger_id: node_id,
|
|
new_var: node_id) {
|
|
alt node_id_to_def(fcx.ccx, new_var) {
|
|
some(d) {
|
|
alt d {
|
|
def_local(nid, _) {
|
|
find_pre_post_expr(fcx, rhs);
|
|
let p = expr_pp(fcx.ccx, rhs);
|
|
set_pre_and_post(fcx.ccx, larger_id, p.precondition,
|
|
p.postcondition);
|
|
}
|
|
_ { find_pre_post_exprs(fcx, [lhs, rhs], larger_id); }
|
|
}
|
|
}
|
|
_ { find_pre_post_exprs(fcx, [lhs, rhs], larger_id); }
|
|
}
|
|
}
|
|
|
|
fn handle_update(fcx: fn_ctxt, parent: @expr, lhs: @expr, rhs: @expr,
|
|
ty: oper_type) {
|
|
find_pre_post_expr(fcx, rhs);
|
|
alt lhs.node {
|
|
expr_path(p) {
|
|
let post = expr_postcond(fcx.ccx, parent);
|
|
let tmp = tritv_clone(post);
|
|
|
|
alt ty {
|
|
oper_move {
|
|
if is_path(rhs) { forget_in_postcond(fcx, parent.id, rhs.id); }
|
|
}
|
|
oper_swap {
|
|
forget_in_postcond(fcx, parent.id, lhs.id);
|
|
forget_in_postcond(fcx, parent.id, rhs.id);
|
|
}
|
|
oper_assign {
|
|
forget_in_postcond(fcx, parent.id, lhs.id);
|
|
}
|
|
_ { }
|
|
}
|
|
|
|
gen_if_local(fcx, lhs, rhs, parent.id, lhs.id);
|
|
alt rhs.node {
|
|
expr_path(p1) {
|
|
let d = local_node_id_to_local_def_id(fcx, lhs.id);
|
|
let d1 = local_node_id_to_local_def_id(fcx, rhs.id);
|
|
alt d {
|
|
some(id) {
|
|
alt d1 {
|
|
some(id1) {
|
|
let instlhs =
|
|
{ident: path_to_ident(p), node: id};
|
|
let instrhs =
|
|
{ident: path_to_ident(p1), node: id1};
|
|
copy_in_poststate_two(fcx, tmp, post, instlhs, instrhs,
|
|
ty);
|
|
}
|
|
_ { }
|
|
}
|
|
}
|
|
_ { }
|
|
}
|
|
}
|
|
_ {/* do nothing */ }
|
|
}
|
|
}
|
|
_ { find_pre_post_expr(fcx, lhs); }
|
|
}
|
|
}
|
|
|
|
fn forget_args_moved_in(fcx: fn_ctxt, parent: @expr, modes: [mode],
|
|
operands: [@expr]) {
|
|
vec::iteri(modes) {|i,mode|
|
|
alt ty::resolved_mode(fcx.ccx.tcx, mode) {
|
|
by_move { forget_in_postcond(fcx, parent.id, operands[i].id); }
|
|
by_ref | by_val | by_mutbl_ref | by_copy { }
|
|
}
|
|
}
|
|
}
|
|
|
|
fn find_pre_post_expr_fn_upvars(fcx: fn_ctxt, e: @expr) {
|
|
let rslt = expr_pp(fcx.ccx, e);
|
|
clear_pp(rslt);
|
|
}
|
|
|
|
/* Fills in annotations as a side effect. Does not rebuild the expr */
|
|
fn find_pre_post_expr(fcx: fn_ctxt, e: @expr) {
|
|
let enclosing = fcx.enclosing;
|
|
let num_local_vars = num_constraints(enclosing);
|
|
fn do_rand_(fcx: fn_ctxt, e: @expr) { find_pre_post_expr(fcx, e); }
|
|
|
|
|
|
alt e.node {
|
|
expr_call(operator, operands, _) {
|
|
/* copy */
|
|
|
|
let mut args = operands;
|
|
args += [operator];
|
|
|
|
find_pre_post_exprs(fcx, args, e.id);
|
|
/* see if the call has any constraints on its type */
|
|
for constraints_expr(fcx.ccx.tcx, operator).each {|c|
|
|
let i =
|
|
bit_num(fcx, substitute_constr_args(fcx.ccx.tcx, args, c));
|
|
require(i, expr_pp(fcx.ccx, e));
|
|
}
|
|
|
|
forget_args_moved_in(fcx, e, callee_modes(fcx, operator.id),
|
|
operands);
|
|
|
|
/* if this is a failing call, its postcondition sets everything */
|
|
alt controlflow_expr(fcx.ccx, operator) {
|
|
noreturn { set_postcond_false(fcx.ccx, e.id); }
|
|
_ { }
|
|
}
|
|
}
|
|
expr_vstore(ee, _) {
|
|
find_pre_post_expr(fcx, ee);
|
|
let p = expr_pp(fcx.ccx, ee);
|
|
set_pre_and_post(fcx.ccx, e.id, p.precondition, p.postcondition);
|
|
}
|
|
expr_vec(args, _) {
|
|
find_pre_post_exprs(fcx, args, e.id);
|
|
}
|
|
expr_path(p) {
|
|
let rslt = expr_pp(fcx.ccx, e);
|
|
clear_pp(rslt);
|
|
}
|
|
expr_new(p, _, v) {
|
|
find_pre_post_exprs(fcx, [p, v], e.id);
|
|
}
|
|
expr_log(_, lvl, arg) {
|
|
find_pre_post_exprs(fcx, [lvl, arg], e.id);
|
|
}
|
|
expr_fn(_, _, _, cap_clause) | expr_fn_block(_, _, cap_clause) {
|
|
find_pre_post_expr_fn_upvars(fcx, e);
|
|
|
|
for (*cap_clause).each { |cap_item|
|
|
let d = local_node_id_to_local_def_id(fcx, cap_item.id);
|
|
option::iter(d, { |id| use_var(fcx, id) });
|
|
}
|
|
|
|
for (*cap_clause).each { |cap_item|
|
|
if cap_item.is_move {
|
|
log(debug, ("forget_in_postcond: ", cap_item));
|
|
forget_in_postcond(fcx, e.id, cap_item.id);
|
|
}
|
|
}
|
|
}
|
|
expr_block(b) {
|
|
find_pre_post_block(fcx, b);
|
|
let p = block_pp(fcx.ccx, b);
|
|
set_pre_and_post(fcx.ccx, e.id, p.precondition, p.postcondition);
|
|
}
|
|
expr_rec(fields, maybe_base) {
|
|
let mut es = field_exprs(fields);
|
|
alt maybe_base { none {/* no-op */ } some(b) { es += [b]; } }
|
|
find_pre_post_exprs(fcx, es, e.id);
|
|
}
|
|
expr_tup(elts) { find_pre_post_exprs(fcx, elts, e.id); }
|
|
expr_move(lhs, rhs) { handle_update(fcx, e, lhs, rhs, oper_move); }
|
|
expr_swap(lhs, rhs) { handle_update(fcx, e, lhs, rhs, oper_swap); }
|
|
expr_assign(lhs, rhs) { handle_update(fcx, e, lhs, rhs, oper_assign); }
|
|
expr_assign_op(_, lhs, rhs) {
|
|
/* Different from expr_assign in that the lhs *must*
|
|
already be initialized */
|
|
|
|
find_pre_post_exprs(fcx, [lhs, rhs], e.id);
|
|
forget_in_postcond(fcx, e.id, lhs.id);
|
|
}
|
|
expr_lit(_) { clear_pp(expr_pp(fcx.ccx, e)); }
|
|
expr_ret(maybe_val) {
|
|
alt maybe_val {
|
|
none {
|
|
clear_precond(fcx.ccx, e.id);
|
|
set_postcond_false(fcx.ccx, e.id);
|
|
}
|
|
some(ret_val) {
|
|
find_pre_post_expr(fcx, ret_val);
|
|
set_precondition(node_id_to_ts_ann(fcx.ccx, e.id),
|
|
expr_precond(fcx.ccx, ret_val));
|
|
set_postcond_false(fcx.ccx, e.id);
|
|
}
|
|
}
|
|
}
|
|
expr_if(antec, conseq, maybe_alt) {
|
|
join_then_else(fcx, antec, conseq, maybe_alt, e.id, plain_if);
|
|
}
|
|
expr_binary(bop, l, r) {
|
|
if lazy_binop(bop) {
|
|
find_pre_post_expr(fcx, l);
|
|
find_pre_post_expr(fcx, r);
|
|
let overall_pre =
|
|
seq_preconds(fcx, [expr_pp(fcx.ccx, l), expr_pp(fcx.ccx, r)]);
|
|
set_precondition(node_id_to_ts_ann(fcx.ccx, e.id), overall_pre);
|
|
set_postcondition(node_id_to_ts_ann(fcx.ccx, e.id),
|
|
expr_postcond(fcx.ccx, l));
|
|
} else { find_pre_post_exprs(fcx, [l, r], e.id); }
|
|
}
|
|
expr_addr_of(_, x) | expr_cast(x, _) | expr_unary(_, x) |
|
|
expr_loop_body(x) | expr_assert(x) | expr_copy(x) {
|
|
find_pre_post_expr(fcx, x);
|
|
copy_pre_post(fcx.ccx, e.id, x);
|
|
}
|
|
expr_while(test, body) {
|
|
find_pre_post_expr(fcx, test);
|
|
find_pre_post_block(fcx, body);
|
|
set_pre_and_post(fcx.ccx, e.id,
|
|
seq_preconds(fcx,
|
|
[expr_pp(fcx.ccx, test),
|
|
block_pp(fcx.ccx, body)]),
|
|
intersect_states(expr_postcond(fcx.ccx, test),
|
|
block_postcond(fcx.ccx, body)));
|
|
}
|
|
expr_loop(body) {
|
|
find_pre_post_block(fcx, body);
|
|
/* Infinite loop: if control passes it, everything is true. */
|
|
let mut loop_postcond = false_postcond(num_local_vars);
|
|
/* Conservative approximation: if the body has any nonlocal exits,
|
|
the poststate is blank since we don't know what parts of it
|
|
execute. */
|
|
if has_nonlocal_exits(body) {
|
|
loop_postcond = empty_poststate(num_local_vars);
|
|
}
|
|
set_pre_and_post(fcx.ccx, e.id, block_precond(fcx.ccx, body),
|
|
loop_postcond);
|
|
}
|
|
expr_index(val, sub) { find_pre_post_exprs(fcx, [val, sub], e.id); }
|
|
expr_alt(ex, alts, _) {
|
|
find_pre_post_expr(fcx, ex);
|
|
fn do_an_alt(fcx: fn_ctxt, an_alt: arm) -> pre_and_post {
|
|
alt an_alt.guard {
|
|
some(e) { find_pre_post_expr(fcx, e); }
|
|
_ {}
|
|
}
|
|
find_pre_post_block(fcx, an_alt.body);
|
|
ret block_pp(fcx.ccx, an_alt.body);
|
|
}
|
|
let mut alt_pps = [];
|
|
for alts.each {|a| alt_pps += [do_an_alt(fcx, a)]; }
|
|
fn combine_pp(antec: pre_and_post, fcx: fn_ctxt, &&pp: pre_and_post,
|
|
&&next: pre_and_post) -> pre_and_post {
|
|
union(pp.precondition, seq_preconds(fcx, [antec, next]));
|
|
intersect(pp.postcondition, next.postcondition);
|
|
ret pp;
|
|
}
|
|
let antec_pp = pp_clone(expr_pp(fcx.ccx, ex));
|
|
let e_pp =
|
|
@{precondition: empty_prestate(num_local_vars),
|
|
postcondition: false_postcond(num_local_vars)};
|
|
let g = bind combine_pp(antec_pp, fcx, _, _);
|
|
let alts_overall_pp =
|
|
vec::foldl(e_pp, alt_pps, g);
|
|
set_pre_and_post(fcx.ccx, e.id, alts_overall_pp.precondition,
|
|
alts_overall_pp.postcondition);
|
|
}
|
|
expr_field(operator, _, _) {
|
|
find_pre_post_expr(fcx, operator);
|
|
copy_pre_post(fcx.ccx, e.id, operator);
|
|
}
|
|
expr_fail(maybe_val) {
|
|
let mut prestate;
|
|
alt maybe_val {
|
|
none { prestate = empty_prestate(num_local_vars); }
|
|
some(fail_val) {
|
|
find_pre_post_expr(fcx, fail_val);
|
|
prestate = expr_precond(fcx.ccx, fail_val);
|
|
}
|
|
}
|
|
set_pre_and_post(fcx.ccx, e.id,
|
|
/* if execution continues after fail,
|
|
then everything is true! */
|
|
prestate, false_postcond(num_local_vars));
|
|
}
|
|
expr_check(_, p) {
|
|
find_pre_post_expr(fcx, p);
|
|
copy_pre_post(fcx.ccx, e.id, p);
|
|
/* predicate p holds after this expression executes */
|
|
|
|
let c: sp_constr = expr_to_constr(fcx.ccx.tcx, p);
|
|
gen(fcx, e.id, c.node);
|
|
}
|
|
expr_if_check(p, conseq, maybe_alt) {
|
|
join_then_else(fcx, p, conseq, maybe_alt, e.id, if_check);
|
|
}
|
|
expr_bind(operator, maybe_args) {
|
|
let mut args = [];
|
|
let mut cmodes = callee_modes(fcx, operator.id);
|
|
let mut modes = [];
|
|
let mut i = 0;
|
|
for maybe_args.each {|expr_opt|
|
|
alt expr_opt {
|
|
none {/* no-op */ }
|
|
some(expr) { modes += [cmodes[i]]; args += [expr]; }
|
|
}
|
|
i += 1;
|
|
}
|
|
args += [operator]; /* ??? order of eval? */
|
|
forget_args_moved_in(fcx, e, modes, args);
|
|
find_pre_post_exprs(fcx, args, e.id);
|
|
}
|
|
expr_break { clear_pp(expr_pp(fcx.ccx, e)); }
|
|
expr_cont { clear_pp(expr_pp(fcx.ccx, e)); }
|
|
expr_mac(_) { fcx.ccx.tcx.sess.bug("unexpanded macro"); }
|
|
}
|
|
}
|
|
|
|
fn find_pre_post_stmt(fcx: fn_ctxt, s: stmt) {
|
|
#debug("stmt =");
|
|
log_stmt(s);
|
|
alt s.node {
|
|
stmt_decl(adecl, id) {
|
|
alt adecl.node {
|
|
decl_local(alocals) {
|
|
let prev_pp = empty_pre_post(num_constraints(fcx.enclosing));
|
|
for alocals.each {|alocal|
|
|
alt alocal.node.init {
|
|
some(an_init) {
|
|
/* LHS always becomes initialized,
|
|
whether or not this is a move */
|
|
find_pre_post_expr(fcx, an_init.expr);
|
|
pat_bindings(fcx.ccx.tcx.def_map, alocal.node.pat)
|
|
{|p_id, _s, _n|
|
|
copy_pre_post(fcx.ccx, p_id, an_init.expr);
|
|
};
|
|
/* Inherit ann from initializer, and add var being
|
|
initialized to the postcondition */
|
|
copy_pre_post(fcx.ccx, id, an_init.expr);
|
|
|
|
let mut p = none;
|
|
alt an_init.expr.node {
|
|
expr_path(_p) { p = some(_p); }
|
|
_ { }
|
|
}
|
|
|
|
pat_bindings(fcx.ccx.tcx.def_map, alocal.node.pat)
|
|
{|p_id, _s, n|
|
|
let ident = path_to_ident(n);
|
|
alt p {
|
|
some(p) {
|
|
copy_in_postcond(fcx, id,
|
|
{ident: ident, node: p_id},
|
|
{ident:
|
|
path_to_ident(p),
|
|
node: an_init.expr.id},
|
|
op_to_oper_ty(an_init.op));
|
|
}
|
|
none { }
|
|
}
|
|
};
|
|
|
|
/* Clear out anything that the previous initializer
|
|
guaranteed */
|
|
let e_pp = expr_pp(fcx.ccx, an_init.expr);
|
|
tritv_copy(prev_pp.precondition,
|
|
seq_preconds(fcx, [prev_pp, e_pp]));
|
|
|
|
/* Include the LHSs too, since those aren't in the
|
|
postconds of the RHSs themselves */
|
|
copy_pre_post_(fcx.ccx, id, prev_pp.precondition,
|
|
prev_pp.postcondition);
|
|
}
|
|
none {
|
|
pat_bindings(fcx.ccx.tcx.def_map, alocal.node.pat)
|
|
{|p_id, _s, _n|
|
|
clear_pp(node_id_to_ts_ann(fcx.ccx, p_id).conditions);
|
|
};
|
|
clear_pp(node_id_to_ts_ann(fcx.ccx, id).conditions);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
decl_item(anitem) {
|
|
clear_pp(node_id_to_ts_ann(fcx.ccx, id).conditions);
|
|
find_pre_post_item(fcx.ccx, *anitem);
|
|
}
|
|
}
|
|
}
|
|
stmt_expr(e, id) | stmt_semi(e, id) {
|
|
find_pre_post_expr(fcx, e);
|
|
copy_pre_post(fcx.ccx, id, e);
|
|
}
|
|
}
|
|
}
|
|
|
|
fn find_pre_post_block(fcx: fn_ctxt, b: blk) {
|
|
/* Want to say that if there is a break or cont in this
|
|
block, then that invalidates the poststate upheld by
|
|
any of the stmts after it.
|
|
Given that the typechecker has run, we know any break will be in
|
|
a block that forms a loop body. So that's ok. There'll never be an
|
|
expr_break outside a loop body, therefore, no expr_break outside a block.
|
|
*/
|
|
|
|
/* Conservative approximation for now: This says that if a block contains
|
|
*any* breaks or conts, then its postcondition doesn't promise anything.
|
|
This will mean that:
|
|
x = 0;
|
|
break;
|
|
|
|
won't have a postcondition that says x is initialized, but that's ok.
|
|
*/
|
|
|
|
let nv = num_constraints(fcx.enclosing);
|
|
fn do_one_(fcx: fn_ctxt, s: @stmt) {
|
|
find_pre_post_stmt(fcx, *s);
|
|
/*
|
|
#error("pre_post for stmt:");
|
|
log_stmt_err(*s);
|
|
#error("is:");
|
|
log_pp_err(stmt_pp(fcx.ccx, *s));
|
|
*/
|
|
}
|
|
for b.node.stmts.each {|s| do_one_(fcx, s); }
|
|
fn do_inner_(fcx: fn_ctxt, &&e: @expr) { find_pre_post_expr(fcx, e); }
|
|
let do_inner = bind do_inner_(fcx, _);
|
|
option::map::<@expr, ()>(b.node.expr, do_inner);
|
|
|
|
let mut pps: [pre_and_post] = [];
|
|
for b.node.stmts.each {|s| pps += [stmt_pp(fcx.ccx, *s)]; }
|
|
alt b.node.expr {
|
|
none {/* no-op */ }
|
|
some(e) { pps += [expr_pp(fcx.ccx, e)]; }
|
|
}
|
|
|
|
let block_precond = seq_preconds(fcx, pps);
|
|
|
|
let mut postconds = [];
|
|
for pps.each {|pp| postconds += [get_post(pp)]; }
|
|
|
|
/* A block may be empty, so this next line ensures that the postconds
|
|
vector is non-empty. */
|
|
postconds += [block_precond];
|
|
|
|
let mut block_postcond = empty_poststate(nv);
|
|
/* conservative approximation */
|
|
|
|
if !has_nonlocal_exits(b) {
|
|
block_postcond = seq_postconds(fcx, postconds);
|
|
}
|
|
set_pre_and_post(fcx.ccx, b.node.id, block_precond, block_postcond);
|
|
}
|
|
|
|
fn find_pre_post_fn(fcx: fn_ctxt, body: blk) {
|
|
find_pre_post_block(fcx, body);
|
|
|
|
// Treat the tail expression as a return statement
|
|
alt body.node.expr {
|
|
some(tailexpr) { set_postcond_false(fcx.ccx, tailexpr.id); }
|
|
none {/* fallthrough */ }
|
|
}
|
|
}
|
|
|
|
fn fn_pre_post(fk: visit::fn_kind, decl: fn_decl, body: blk, sp: span,
|
|
id: node_id,
|
|
ccx: crate_ctxt, v: visit::vt<crate_ctxt>) {
|
|
visit::visit_fn(fk, decl, body, sp, id, ccx, v);
|
|
assert (ccx.fm.contains_key(id));
|
|
let fcx =
|
|
{enclosing: ccx.fm.get(id),
|
|
id: id,
|
|
name: visit::name_of_fn(fk),
|
|
ccx: ccx};
|
|
find_pre_post_fn(fcx, body);
|
|
}
|
|
|
|
//
|
|
// Local Variables:
|
|
// mode: rust
|
|
// fill-column: 78;
|
|
// indent-tabs-mode: nil
|
|
// c-basic-offset: 4
|
|
// buffer-file-coding-system: utf-8-unix
|
|
// End:
|
|
//
|