rust/src/comp/middle/tstate/states.rs

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import ann::*;
import aux::*;
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import tritv::{tritv_clone, tritv_set, ttrue};
import bitvectors::*;
import pat_util::*;
import syntax::ast::*;
import syntax::ast_util::*;
import syntax::codemap::span;
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import middle::ty::{expr_ty, type_is_bot};
import util::common::*;
import driver::session::session;
fn forbid_upvar(fcx: fn_ctxt, rhs_id: node_id, sp: span, t: oper_type) {
alt t {
oper_move {
alt local_node_id_to_def(fcx, rhs_id) {
some(def_upvar(_, _, _)) {
fcx.ccx.tcx.sess.span_err(sp,
"Tried to deinitialize a variable \
declared in a different scope");
}
_ { }
}
}
_ {/* do nothing */ }
}
}
fn handle_move_or_copy(fcx: fn_ctxt, post: poststate, rhs_path: @path,
rhs_id: node_id, instlhs: inst, init_op: init_op) {
forbid_upvar(fcx, rhs_id, rhs_path.span, op_to_oper_ty(init_op));
let rhs_d_id = local_node_id_to_def_id(fcx, rhs_id);
alt rhs_d_id {
some(rhsid) {
// RHS is a local var
let instrhs =
{ident: path_to_ident(rhs_path), node: rhsid.node};
copy_in_poststate(fcx, post, instlhs, instrhs,
op_to_oper_ty(init_op));
}
_ {
// not a local -- do nothing
}
}
}
fn handle_fail(fcx: fn_ctxt, pres:prestate, post:poststate) {
// Remember what the old value of the "I return" trit was, so that
// we can avoid changing that (if it was true, there was a return
// that dominates this fail and the fail is unreachable)
if !promises(fcx, pres, fcx.enclosing.i_return)
// (only if we're in a diverging function -- you can fail when
// you're supposed to return, but not vice versa).
&& fcx.enclosing.cf == noreturn {
kill_poststate_(fcx, fcx.enclosing.i_return, post);
} else {
// This code is unreachable (it's dominated by a return),
// so doesn't diverge.
kill_poststate_(fcx, fcx.enclosing.i_diverge, post);
}
}
fn seq_states(fcx: fn_ctxt, pres: prestate, bindings: [binding]) ->
{changed: bool, post: poststate} {
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let changed = false;
let post = tritv_clone(pres);
for b: binding in bindings {
alt b.rhs {
some(an_init) {
// an expression, with or without a destination
changed |=
find_pre_post_state_expr(fcx, post, an_init.expr) || changed;
post = tritv_clone(expr_poststate(fcx.ccx, an_init.expr));
for i: inst in b.lhs {
alt an_init.expr.node {
expr_path(p) {
handle_move_or_copy(fcx, post, p, an_init.expr.id, i,
an_init.op);
}
_ { }
}
set_in_poststate_ident(fcx, i.node, i.ident, post);
}
// Forget the RHS if we just moved it.
if an_init.op == init_move {
forget_in_poststate(fcx, post, an_init.expr.id);
}
}
none {
for i: inst in b.lhs {
// variables w/o an initializer
clear_in_poststate_ident_(fcx, i.node, i.ident, post);
}
}
}
}
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ret {changed: changed, post: post};
}
fn find_pre_post_state_sub(fcx: fn_ctxt, pres: prestate, e: @expr,
parent: node_id, c: option<tsconstr>) -> bool {
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let changed = find_pre_post_state_expr(fcx, pres, e);
changed = set_prestate_ann(fcx.ccx, parent, pres) || changed;
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let post = tritv_clone(expr_poststate(fcx.ccx, e));
alt c {
none { }
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some(c1) { set_in_poststate_(bit_num(fcx, c1), post); }
}
changed = set_poststate_ann(fcx.ccx, parent, post) || changed;
ret changed;
}
fn find_pre_post_state_two(fcx: fn_ctxt, pres: prestate, lhs: @expr,
rhs: @expr, parent: node_id, ty: oper_type) ->
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bool {
let changed = set_prestate_ann(fcx.ccx, parent, pres);
changed = find_pre_post_state_expr(fcx, pres, lhs) || changed;
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changed =
find_pre_post_state_expr(fcx, expr_poststate(fcx.ccx, lhs), rhs) ||
changed;
forbid_upvar(fcx, rhs.id, rhs.span, ty);
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let post = tritv_clone(expr_poststate(fcx.ccx, rhs));
alt lhs.node {
expr_path(p) {
// for termination, need to make sure intermediate changes don't set
// changed flag
// tmp remembers "old" constraints we'd otherwise forget,
// for substitution purposes
let tmp = tritv_clone(post);
alt ty {
oper_move {
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if is_path(rhs) { forget_in_poststate(fcx, post, rhs.id); }
forget_in_poststate_still_init(fcx, post, lhs.id);
}
oper_swap {
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forget_in_poststate_still_init(fcx, post, lhs.id);
forget_in_poststate_still_init(fcx, post, rhs.id);
}
_ { forget_in_poststate_still_init(fcx, post, lhs.id); }
}
gen_if_local(fcx, post, lhs);
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};
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let instrhs =
{ident: path_to_ident(p1), node: id1};
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copy_in_poststate_two(fcx, tmp, post, instlhs, instrhs,
ty);
}
_ { }
}
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}
_ { }
}
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}
_ {/* do nothing */ }
}
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}
_ { }
}
changed = set_poststate_ann(fcx.ccx, parent, post) || changed;
ret changed;
}
fn find_pre_post_state_call(fcx: fn_ctxt, pres: prestate, a: @expr,
id: node_id, ops: [init_op], bs: [@expr],
cf: ret_style) -> bool {
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let changed = find_pre_post_state_expr(fcx, pres, a);
// FIXME: This could be a typestate constraint
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if vec::len(bs) != vec::len(ops) {
fcx.ccx.tcx.sess.span_bug(a.span,
#fmt["mismatched arg lengths: \
%u exprs vs. %u ops",
vec::len(bs), vec::len(ops)]);
}
ret find_pre_post_state_exprs(fcx, expr_poststate(fcx.ccx, a), id, ops,
bs, cf) || changed;
}
fn find_pre_post_state_exprs(fcx: fn_ctxt, pres: prestate, id: node_id,
ops: [init_op], es: [@expr], cf: ret_style) ->
bool {
let rs = seq_states(fcx, pres, anon_bindings(ops, es));
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let changed = rs.changed | set_prestate_ann(fcx.ccx, id, pres);
/* if this is a failing call, it sets everything as initialized */
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alt cf {
noreturn {
let post = false_postcond(num_constraints(fcx.enclosing));
handle_fail(fcx, pres, post);
changed |= set_poststate_ann(fcx.ccx, id, post);
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}
_ { changed |= set_poststate_ann(fcx.ccx, id, rs.post); }
}
ret changed;
}
fn find_pre_post_state_loop(fcx: fn_ctxt, pres: prestate, l: @local,
index: @expr, body: blk, id: node_id) -> bool {
// I'm confused about this -- how does the poststate for the body
// ever grow larger? It seems like it can't?
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let loop_pres = intersect_states(pres, block_poststate(fcx.ccx, body));
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let changed =
set_prestate_ann(fcx.ccx, id, loop_pres) |
find_pre_post_state_expr(fcx, pres, index);
// Make sure the index vars are considered initialized
// in the body
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let index_post = tritv_clone(expr_poststate(fcx.ccx, index));
pat_bindings(pat_util::normalize_pat(fcx.ccx.tcx, l.node.pat))
{|p_id, _s, n|
set_in_poststate_ident(fcx, p_id, path_to_ident(n), index_post);
};
changed |= find_pre_post_state_block(fcx, index_post, body);
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if has_nonlocal_exits(body) {
// See [Break-unsound]
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ret changed | set_poststate_ann(fcx.ccx, id, pres);
} else {
let res_p =
intersect_states(expr_poststate(fcx.ccx, index),
block_poststate(fcx.ccx, body));
ret changed | set_poststate_ann(fcx.ccx, id, res_p);
}
}
fn gen_if_local(fcx: fn_ctxt, p: poststate, e: @expr) -> bool {
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alt e.node {
expr_path(pth) {
alt fcx.ccx.tcx.def_map.find(e.id) {
some(def_local(loc)) {
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ret set_in_poststate_ident(fcx, loc.node,
path_to_ident(pth), p);
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}
_ { ret false; }
}
}
_ { ret false; }
}
}
fn join_then_else(fcx: fn_ctxt, antec: @expr, conseq: blk,
maybe_alt: option<@expr>, id: node_id, chk: if_ty,
pres: prestate) -> bool {
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let changed =
set_prestate_ann(fcx.ccx, id, pres) |
find_pre_post_state_expr(fcx, pres, antec);
/*
log_err("join_then_else:");
log_expr_err(*antec);
log_bitv_err(fcx, expr_prestate(fcx.ccx, antec));
log_bitv_err(fcx, expr_poststate(fcx.ccx, antec));
log_block_err(conseq);
log_bitv_err(fcx, block_prestate(fcx.ccx, conseq));
log_bitv_err(fcx, block_poststate(fcx.ccx, conseq));
log_err("****");
log_bitv_err(fcx, expr_precond(fcx.ccx, antec));
log_bitv_err(fcx, expr_postcond(fcx.ccx, antec));
log_bitv_err(fcx, block_precond(fcx.ccx, conseq));
log_bitv_err(fcx, block_postcond(fcx.ccx, conseq));
*/
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alt maybe_alt {
none {
alt chk {
if_check {
let c: sp_constr = expr_to_constr(fcx.ccx.tcx, antec);
let conseq_prestate = tritv_clone(expr_poststate(fcx.ccx, antec));
tritv_set(bit_num(fcx, c.node), conseq_prestate, ttrue);
changed |=
find_pre_post_state_block(fcx, conseq_prestate, conseq) |
set_poststate_ann(fcx.ccx, id,
expr_poststate(fcx.ccx, antec));
}
_ {
changed |=
find_pre_post_state_block(fcx, expr_poststate(fcx.ccx, antec),
conseq) |
set_poststate_ann(fcx.ccx, id,
expr_poststate(fcx.ccx, antec));
}
}
}
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some(altern) {
changed |=
find_pre_post_state_expr(fcx, expr_poststate(fcx.ccx, antec),
altern);
let conseq_prestate = expr_poststate(fcx.ccx, antec);
alt chk {
if_check {
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let c: sp_constr = expr_to_constr(fcx.ccx.tcx, antec);
conseq_prestate = tritv_clone(conseq_prestate);
tritv_set(bit_num(fcx, c.node), conseq_prestate, ttrue);
}
_ { }
}
changed |= find_pre_post_state_block(fcx, conseq_prestate, conseq);
let poststate_res =
intersect_states(block_poststate(fcx.ccx, conseq),
expr_poststate(fcx.ccx, altern));
/*
fcx.ccx.tcx.sess.span_note(antec.span,
"poststate_res = " + aux::tritv_to_str(fcx, poststate_res));
fcx.ccx.tcx.sess.span_note(antec.span,
"altern poststate = " +
aux::tritv_to_str(fcx, expr_poststate(fcx.ccx, altern)));
fcx.ccx.tcx.sess.span_note(antec.span,
"conseq poststate = " + aux::tritv_to_str(fcx,
block_poststate(fcx.ccx, conseq)));
*/
changed |= set_poststate_ann(fcx.ccx, id, poststate_res);
}
}
ret changed;
}
fn find_pre_post_state_cap_clause(fcx: fn_ctxt, e_id: node_id,
pres: prestate, cap_clause: capture_clause)
-> bool
{
let ccx = fcx.ccx;
let pres_changed = set_prestate_ann(ccx, e_id, pres);
let post = tritv_clone(pres);
vec::iter(cap_clause.moves) { |cap_item|
forget_in_poststate(fcx, post, cap_item.id);
}
ret set_poststate_ann(ccx, e_id, post) || pres_changed;
}
fn find_pre_post_state_expr(fcx: fn_ctxt, pres: prestate, e: @expr) -> bool {
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let num_constrs = num_constraints(fcx.enclosing);
alt e.node {
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expr_vec(elts, _) {
ret find_pre_post_state_exprs(fcx, pres, e.id,
vec::init_elt(vec::len(elts),
init_assign), elts,
return_val);
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}
expr_call(operator, operands, _) {
ret find_pre_post_state_call(fcx, pres, operator, e.id,
callee_arg_init_ops(fcx, operator.id),
operands,
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controlflow_expr(fcx.ccx, operator));
}
expr_bind(operator, maybe_args) {
let args = [];
let callee_ops = callee_arg_init_ops(fcx, operator.id);
let ops = [];
let i = 0;
for a_opt: option<@expr> in maybe_args {
alt a_opt {
none {/* no-op */ }
some(a) { ops += [callee_ops[i]]; args += [a]; }
}
i += 1;
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}
ret find_pre_post_state_call(fcx, pres, operator, e.id, ops, args,
return_val);
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}
expr_path(_) { ret pure_exp(fcx.ccx, e.id, pres); }
expr_log(_, lvl, ex) {
ret find_pre_post_state_two(fcx, pres, lvl, ex, e.id, oper_pure);
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}
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expr_mac(_) { fcx.ccx.tcx.sess.bug("unexpanded macro"); }
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expr_lit(l) { ret pure_exp(fcx.ccx, e.id, pres); }
expr_fn(_, _, _, cap_clause) {
ret find_pre_post_state_cap_clause(fcx, e.id, pres, *cap_clause);
}
expr_fn_block(_, _) { ret pure_exp(fcx.ccx, e.id, pres); }
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expr_block(b) {
ret find_pre_post_state_block(fcx, pres, b) |
set_prestate_ann(fcx.ccx, e.id, pres) |
set_poststate_ann(fcx.ccx, e.id, block_poststate(fcx.ccx, b));
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}
expr_rec(fields, maybe_base) {
let exs = field_exprs(fields);
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let changed =
find_pre_post_state_exprs(fcx, pres, e.id,
vec::init_elt(vec::len(fields),
init_assign),
exs, return_val);
let base_pres = alt vec::last(exs) { none { pres }
some(f) { expr_poststate(fcx.ccx, f) }};
option::may(maybe_base, {|base|
changed |= find_pre_post_state_expr(fcx, base_pres, base) |
set_poststate_ann(fcx.ccx, e.id,
expr_poststate(fcx.ccx, base))});
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ret changed;
}
expr_tup(elts) {
ret find_pre_post_state_exprs(fcx, pres, e.id,
vec::init_elt(vec::len(elts),
init_assign), elts,
return_val);
}
expr_copy(a) { ret find_pre_post_state_sub(fcx, pres, a, e.id, none); }
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expr_move(lhs, rhs) {
ret find_pre_post_state_two(fcx, pres, lhs, rhs, e.id, oper_move);
}
expr_assign(lhs, rhs) {
ret find_pre_post_state_two(fcx, pres, lhs, rhs, e.id, oper_assign);
}
expr_swap(lhs, rhs) {
ret find_pre_post_state_two(fcx, pres, lhs, rhs, e.id, oper_swap);
// Could be more precise and actually swap the role of
// lhs and rhs in constraints
}
expr_ret(maybe_ret_val) {
let changed = set_prestate_ann(fcx.ccx, e.id, pres);
/* normally, everything is true if execution continues after
a ret expression (since execution never continues locally
after a ret expression */
// FIXME should factor this out
let post = false_postcond(num_constrs);
// except for the "diverges" bit...
kill_poststate_(fcx, fcx.enclosing.i_diverge, post);
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set_poststate_ann(fcx.ccx, e.id, post);
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alt maybe_ret_val {
none {/* do nothing */ }
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some(ret_val) {
changed |= find_pre_post_state_expr(fcx, pres, ret_val);
}
}
ret changed;
}
expr_be(val) {
let changed = set_prestate_ann(fcx.ccx, e.id, pres);
let post = false_postcond(num_constrs);
// except for the "diverges" bit...
kill_poststate_(fcx, fcx.enclosing.i_diverge, post);
set_poststate_ann(fcx.ccx, e.id, post);
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ret changed | find_pre_post_state_expr(fcx, pres, val);
}
expr_if(antec, conseq, maybe_alt) {
ret join_then_else(fcx, antec, conseq, maybe_alt, e.id, plain_if,
pres);
}
expr_binary(bop, l, r) {
if lazy_binop(bop) {
let changed = find_pre_post_state_expr(fcx, pres, l);
changed |=
find_pre_post_state_expr(fcx, expr_poststate(fcx.ccx, l), r);
ret changed | set_prestate_ann(fcx.ccx, e.id, pres) |
set_poststate_ann(fcx.ccx, e.id,
expr_poststate(fcx.ccx, l));
} else {
ret find_pre_post_state_two(fcx, pres, l, r, e.id, oper_pure);
}
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}
expr_assign_op(op, lhs, rhs) {
ret find_pre_post_state_two(fcx, pres, lhs, rhs, e.id,
oper_assign_op);
}
expr_while(test, body) {
/*
#error("in a while loop:");
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log_expr_err(*e);
aux::log_tritv_err(fcx, block_poststate(fcx.ccx, body));
aux::log_tritv_err(fcx, pres);
*/
let loop_pres =
intersect_states(block_poststate(fcx.ccx, body), pres);
// aux::log_tritv_err(fcx, loop_pres);
// #error("---------------");
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let changed =
set_prestate_ann(fcx.ccx, e.id, loop_pres) |
find_pre_post_state_expr(fcx, loop_pres, test) |
find_pre_post_state_block(fcx, expr_poststate(fcx.ccx, test),
body);
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/* conservative approximation: if a loop contains a break
or cont, we assume nothing about the poststate */
/* which is still unsound -- see [Break-unsound] */
if has_nonlocal_exits(body) {
ret changed | set_poststate_ann(fcx.ccx, e.id, pres);
} else {
let e_post = expr_poststate(fcx.ccx, test);
let b_post = block_poststate(fcx.ccx, body);
ret changed |
set_poststate_ann(fcx.ccx, e.id,
intersect_states(e_post, b_post));
}
}
expr_do_while(body, test) {
let loop_pres = intersect_states(expr_poststate(fcx.ccx, test), pres);
let changed = set_prestate_ann(fcx.ccx, e.id, loop_pres);
changed |= find_pre_post_state_block(fcx, loop_pres, body);
/* conservative approximination: if the body of the loop
could break or cont, we revert to the prestate
(TODO: could treat cont differently from break, since
if there's a cont, the test will execute) */
changed |=
find_pre_post_state_expr(fcx, block_poststate(fcx.ccx, body),
test);
let breaks = has_nonlocal_exits(body);
if breaks {
// this should probably be true_poststate and not pres,
// b/c the body could invalidate stuff
// FIXME [Break-unsound]
// This is unsound as it is -- consider
// while (true) {
// x <- y;
// break;
// }
// The poststate wouldn't take into account that
// y gets deinitialized
changed |= set_poststate_ann(fcx.ccx, e.id, pres);
} else {
changed |=
set_poststate_ann(fcx.ccx, e.id,
expr_poststate(fcx.ccx, test));
}
ret changed;
}
expr_for(d, index, body) {
ret find_pre_post_state_loop(fcx, pres, d, index, body, e.id);
}
expr_index(val, sub) {
ret find_pre_post_state_two(fcx, pres, val, sub, e.id, oper_pure);
}
expr_alt(val, alts) {
let changed =
set_prestate_ann(fcx.ccx, e.id, pres) |
find_pre_post_state_expr(fcx, pres, val);
let e_post = expr_poststate(fcx.ccx, val);
let a_post;
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if vec::len(alts) > 0u {
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a_post = false_postcond(num_constrs);
for an_alt: arm in alts {
alt an_alt.guard {
some(e) {
changed |= find_pre_post_state_expr(fcx, e_post, e);
}
_ {}
}
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changed |=
find_pre_post_state_block(fcx, e_post, an_alt.body);
intersect(a_post, block_poststate(fcx.ccx, an_alt.body));
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// We deliberately do *not* update changed here, because
// we'd go into an infinite loop that way, and the change
// gets made after the if expression.
}
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} else {
// No alts; poststate is the poststate of the test
a_post = e_post;
}
ret changed | set_poststate_ann(fcx.ccx, e.id, a_post);
}
expr_field(val, _, _) {
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ret find_pre_post_state_sub(fcx, pres, val, e.id, none);
}
expr_unary(_, operand) {
ret find_pre_post_state_sub(fcx, pres, operand, e.id, none);
}
expr_cast(operand, _) {
ret find_pre_post_state_sub(fcx, pres, operand, e.id, none);
}
expr_fail(maybe_fail_val) {
// FIXME Should factor out this code,
// which also appears in find_pre_post_state_exprs
/* if execution continues after fail, then everything is true!
woo! */
let post = false_postcond(num_constrs);
handle_fail(fcx, pres, post);
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ret set_prestate_ann(fcx.ccx, e.id, pres) |
set_poststate_ann(fcx.ccx, e.id, post) |
option::maybe(false, maybe_fail_val, {|fail_val|
find_pre_post_state_expr(fcx, pres, fail_val)});
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}
expr_assert(p) {
ret find_pre_post_state_sub(fcx, pres, p, e.id, none);
}
expr_check(_, p) {
/* predicate p holds after this expression executes */
let c: sp_constr = expr_to_constr(fcx.ccx.tcx, p);
ret find_pre_post_state_sub(fcx, pres, p, e.id, some(c.node));
}
expr_if_check(p, conseq, maybe_alt) {
ret join_then_else(fcx, p, conseq, maybe_alt, e.id, if_check, pres);
}
expr_break { ret pure_exp(fcx.ccx, e.id, pres); }
expr_cont { ret pure_exp(fcx.ccx, e.id, pres); }
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}
}
fn find_pre_post_state_stmt(fcx: fn_ctxt, pres: prestate, s: @stmt) -> bool {
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let stmt_ann = stmt_to_ann(fcx.ccx, *s);
log(debug, "[" + fcx.name + "]");
#debug("*At beginning: stmt = ");
log_stmt(*s);
#debug("*prestate = ");
log(debug, tritv::to_str(stmt_ann.states.prestate));
#debug("*poststate =");
log(debug, tritv::to_str(stmt_ann.states.prestate));
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alt s.node {
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stmt_decl(adecl, id) {
alt adecl.node {
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decl_local(alocals) {
set_prestate(stmt_ann, pres);
let c_and_p = seq_states(fcx, pres,
locals_to_bindings(fcx.ccx.tcx, alocals));
/* important to do this in one step to ensure
termination (don't want to set changed to true
for intermediate changes) */
let changed =
set_poststate(stmt_ann, c_and_p.post) | c_and_p.changed;
#debug("Summary: stmt = ");
log_stmt(*s);
#debug("prestate = ");
log(debug, tritv::to_str(stmt_ann.states.prestate));
#debug("poststate =");
log(debug, tritv::to_str(stmt_ann.states.prestate));
#debug("changed =");
log(debug, changed);
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ret changed;
}
decl_item(an_item) {
ret set_prestate(stmt_ann, pres) | set_poststate(stmt_ann, pres);
/* the outer visitor will recurse into the item */
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}
}
}
stmt_expr(ex, _) | stmt_semi(ex, _) {
let changed =
find_pre_post_state_expr(fcx, pres, ex) |
set_prestate(stmt_ann, expr_prestate(fcx.ccx, ex)) |
set_poststate(stmt_ann, expr_poststate(fcx.ccx, ex));
#debug("Finally:");
log_stmt(*s);
log(debug, "prestate = ");
log(debug, tritv::to_str(stmt_ann.states.prestate));
#debug("poststate =");
log(debug, (tritv::to_str(stmt_ann.states.poststate)));
#debug("changed =");
ret changed;
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}
_ { ret false; }
}
}
/* Updates the pre- and post-states of statements in the block,
returns a boolean flag saying whether any pre- or poststates changed */
fn find_pre_post_state_block(fcx: fn_ctxt, pres0: prestate, b: blk) -> bool {
/* First, set the pre-states and post-states for every expression */
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let pres = pres0;
/* Iterate over each stmt. The new prestate is <pres>. The poststate
consist of improving <pres> with whatever variables this stmt
initializes. Then <pres> becomes the new poststate. */
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let changed = false;
for s: @stmt in b.node.stmts {
changed |= find_pre_post_state_stmt(fcx, pres, s);
pres = stmt_poststate(fcx.ccx, *s);
}
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let post = pres;
alt b.node.expr {
none { }
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some(e) {
changed |= find_pre_post_state_expr(fcx, pres, e);
post = expr_poststate(fcx.ccx, e);
}
}
set_prestate_ann(fcx.ccx, b.node.id, pres0);
set_poststate_ann(fcx.ccx, b.node.id, post);
/*
#error("For block:");
log_block_err(b);
#error("poststate = ");
log_states_err(block_states(fcx.ccx, b));
#error("pres0:");
log_tritv_err(fcx, pres0);
#error("post:");
log_tritv_err(fcx, post);
#error("changed = ");
log(error, changed);
*/
ret changed;
}
fn find_pre_post_state_fn(fcx: fn_ctxt,
f_decl: fn_decl,
f_body: blk) -> bool {
let num_constrs = num_constraints(fcx.enclosing);
// All constraints are considered false until proven otherwise.
// This ensures that intersect works correctly.
kill_all_prestate(fcx, f_body.node.id);
// Arguments start out initialized
let block_pre = block_prestate(fcx.ccx, f_body);
for a: arg in f_decl.inputs {
set_in_prestate_constr(fcx, ninit(a.id, a.ident), block_pre);
}
// Instantiate any constraints on the arguments so we can use them
for c: @constr in f_decl.constraints {
let tsc = ast_constr_to_ts_constr(fcx.ccx.tcx, f_decl.inputs, c);
set_in_prestate_constr(fcx, tsc, block_pre);
}
let changed = find_pre_post_state_block(fcx, block_pre, f_body);
// Treat the tail expression as a return statement
alt f_body.node.expr {
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some(tailexpr) {
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// We don't want to clear the diverges bit for bottom typed things,
// which really do diverge. I feel like there is a cleaner way
// to do this than checking the type.
if !type_is_bot(expr_ty(fcx.ccx.tcx, tailexpr)) {
let post = false_postcond(num_constrs);
// except for the "diverges" bit...
kill_poststate_(fcx, fcx.enclosing.i_diverge, post);
set_poststate_ann(fcx.ccx, f_body.node.id, post);
}
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}
none {/* fallthrough */ }
}
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/*
#error("find_pre_post_state_fn");
log(error, changed);
fcx.ccx.tcx.sess.span_note(f_body.span, fcx.name);
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*/
ret changed;
}
//
// Local Variables:
// mode: rust
// fill-column: 78;
// indent-tabs-mode: nil
// c-basic-offset: 4
// buffer-file-coding-system: utf-8-unix
// End:
//