7e77bf1769
notation for closures, and disable the feature gate for `once fn` if used with the `~` sigil.
1020 lines
36 KiB
Rust
1020 lines
36 KiB
Rust
// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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/*!
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* A module for propagating forward dataflow information. The analysis
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* assumes that the items to be propagated can be represented as bits
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* and thus uses bitvectors. Your job is simply to specify the so-called
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* GEN and KILL bits for each expression.
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*/
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use std::cast;
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use std::rt::io;
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use std::uint;
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use std::vec;
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use std::hashmap::HashMap;
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use syntax::ast;
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use syntax::ast_util;
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use syntax::ast_util::id_range;
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use syntax::print::{pp, pprust};
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use middle::ty;
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use middle::typeck;
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use util::ppaux::Repr;
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#[deriving(Clone)]
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pub struct DataFlowContext<O> {
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priv tcx: ty::ctxt,
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priv method_map: typeck::method_map,
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/// the data flow operator
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priv oper: O,
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/// number of bits to propagate per id
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priv bits_per_id: uint,
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/// number of words we will use to store bits_per_id.
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/// equal to bits_per_id/uint::bits rounded up.
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priv words_per_id: uint,
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// mapping from node to bitset index.
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priv nodeid_to_bitset: HashMap<ast::NodeId,uint>,
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// Bit sets per id. The following three fields (`gens`, `kills`,
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// and `on_entry`) all have the same structure. For each id in
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// `id_range`, there is a range of words equal to `words_per_id`.
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// So, to access the bits for any given id, you take a slice of
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// the full vector (see the method `compute_id_range()`).
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/// bits generated as we exit the scope `id`. Updated by `add_gen()`.
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priv gens: ~[uint],
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/// bits killed as we exit the scope `id`. Updated by `add_kill()`.
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priv kills: ~[uint],
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/// bits that are valid on entry to the scope `id`. Updated by
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/// `propagate()`.
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priv on_entry: ~[uint]
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}
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/// Parameterization for the precise form of data flow that is used.
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pub trait DataFlowOperator {
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/// Specifies the initial value for each bit in the `on_entry` set
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fn initial_value(&self) -> bool;
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/// Joins two predecessor bits together, typically either `|` or `&`
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fn join(&self, succ: uint, pred: uint) -> uint;
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/// True if we should propagate through closures
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fn walk_closures(&self) -> bool;
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}
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struct PropagationContext<'self, O> {
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dfcx: &'self mut DataFlowContext<O>,
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changed: bool
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}
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struct LoopScope<'self> {
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loop_id: ast::NodeId,
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break_bits: ~[uint]
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}
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impl<O:DataFlowOperator> pprust::pp_ann for DataFlowContext<O> {
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fn pre(&self, node: pprust::ann_node) {
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let (ps, id) = match node {
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pprust::node_expr(ps, expr) => (ps, expr.id),
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pprust::node_block(ps, blk) => (ps, blk.id),
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pprust::node_item(ps, _) => (ps, 0),
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pprust::node_pat(ps, pat) => (ps, pat.id)
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};
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if self.nodeid_to_bitset.contains_key(&id) {
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let (start, end) = self.compute_id_range_frozen(id);
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let on_entry = self.on_entry.slice(start, end);
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let entry_str = bits_to_str(on_entry);
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let gens = self.gens.slice(start, end);
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let gens_str = if gens.iter().any(|&u| u != 0) {
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format!(" gen: {}", bits_to_str(gens))
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} else {
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~""
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};
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let kills = self.kills.slice(start, end);
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let kills_str = if kills.iter().any(|&u| u != 0) {
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format!(" kill: {}", bits_to_str(kills))
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} else {
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~""
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};
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let comment_str = format!("id {}: {}{}{}",
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id, entry_str, gens_str, kills_str);
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pprust::synth_comment(ps, comment_str);
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pp::space(ps.s);
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}
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}
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}
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impl<O:DataFlowOperator> DataFlowContext<O> {
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pub fn new(tcx: ty::ctxt,
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method_map: typeck::method_map,
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oper: O,
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id_range: id_range,
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bits_per_id: uint) -> DataFlowContext<O> {
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let words_per_id = (bits_per_id + uint::bits - 1) / uint::bits;
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debug!("DataFlowContext::new(id_range={:?}, bits_per_id={:?}, words_per_id={:?})",
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id_range, bits_per_id, words_per_id);
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let gens = ~[];
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let kills = ~[];
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let on_entry = ~[];
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DataFlowContext {
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tcx: tcx,
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method_map: method_map,
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words_per_id: words_per_id,
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nodeid_to_bitset: HashMap::new(),
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bits_per_id: bits_per_id,
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oper: oper,
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gens: gens,
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kills: kills,
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on_entry: on_entry
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}
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}
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pub fn add_gen(&mut self, id: ast::NodeId, bit: uint) {
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//! Indicates that `id` generates `bit`
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debug!("add_gen(id={:?}, bit={:?})", id, bit);
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let (start, end) = self.compute_id_range(id);
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{
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let gens = self.gens.mut_slice(start, end);
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set_bit(gens, bit);
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}
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}
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pub fn add_kill(&mut self, id: ast::NodeId, bit: uint) {
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//! Indicates that `id` kills `bit`
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debug!("add_kill(id={:?}, bit={:?})", id, bit);
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let (start, end) = self.compute_id_range(id);
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{
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let kills = self.kills.mut_slice(start, end);
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set_bit(kills, bit);
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}
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}
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fn apply_gen_kill(&mut self, id: ast::NodeId, bits: &mut [uint]) {
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//! Applies the gen and kill sets for `id` to `bits`
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debug!("apply_gen_kill(id={:?}, bits={}) [before]",
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id, mut_bits_to_str(bits));
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let (start, end) = self.compute_id_range(id);
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let gens = self.gens.slice(start, end);
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bitwise(bits, gens, |a, b| a | b);
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let kills = self.kills.slice(start, end);
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bitwise(bits, kills, |a, b| a & !b);
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debug!("apply_gen_kill(id={:?}, bits={}) [after]",
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id, mut_bits_to_str(bits));
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}
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fn apply_kill(&mut self, id: ast::NodeId, bits: &mut [uint]) {
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debug!("apply_kill(id={:?}, bits={}) [before]",
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id, mut_bits_to_str(bits));
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let (start, end) = self.compute_id_range(id);
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let kills = self.kills.slice(start, end);
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bitwise(bits, kills, |a, b| a & !b);
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debug!("apply_kill(id={:?}, bits={}) [after]",
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id, mut_bits_to_str(bits));
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}
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fn compute_id_range_frozen(&self, id: ast::NodeId) -> (uint, uint) {
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let n = *self.nodeid_to_bitset.get(&id);
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let start = n * self.words_per_id;
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let end = start + self.words_per_id;
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(start, end)
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}
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fn compute_id_range(&mut self, id: ast::NodeId) -> (uint, uint) {
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let mut expanded = false;
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let len = self.nodeid_to_bitset.len();
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let n = do self.nodeid_to_bitset.find_or_insert_with(id) |_| {
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expanded = true;
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len
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};
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if expanded {
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let entry = if self.oper.initial_value() { uint::max_value } else {0};
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do self.words_per_id.times {
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self.gens.push(0);
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self.kills.push(0);
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self.on_entry.push(entry);
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}
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}
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let start = *n * self.words_per_id;
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let end = start + self.words_per_id;
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assert!(start < self.gens.len());
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assert!(end <= self.gens.len());
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assert!(self.gens.len() == self.kills.len());
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assert!(self.gens.len() == self.on_entry.len());
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(start, end)
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}
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pub fn each_bit_on_entry_frozen(&self,
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id: ast::NodeId,
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f: &fn(uint) -> bool) -> bool {
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//! Iterates through each bit that is set on entry to `id`.
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//! Only useful after `propagate()` has been called.
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if !self.nodeid_to_bitset.contains_key(&id) {
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return true;
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}
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let (start, end) = self.compute_id_range_frozen(id);
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let on_entry = self.on_entry.slice(start, end);
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debug!("each_bit_on_entry_frozen(id={:?}, on_entry={})",
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id, bits_to_str(on_entry));
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self.each_bit(on_entry, f)
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}
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pub fn each_bit_on_entry(&mut self,
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id: ast::NodeId,
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f: &fn(uint) -> bool) -> bool {
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//! Iterates through each bit that is set on entry to `id`.
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//! Only useful after `propagate()` has been called.
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let (start, end) = self.compute_id_range(id);
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let on_entry = self.on_entry.slice(start, end);
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debug!("each_bit_on_entry(id={:?}, on_entry={})",
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id, bits_to_str(on_entry));
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self.each_bit(on_entry, f)
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}
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pub fn each_gen_bit(&mut self,
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id: ast::NodeId,
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f: &fn(uint) -> bool) -> bool {
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//! Iterates through each bit in the gen set for `id`.
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let (start, end) = self.compute_id_range(id);
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let gens = self.gens.slice(start, end);
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debug!("each_gen_bit(id={:?}, gens={})",
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id, bits_to_str(gens));
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self.each_bit(gens, f)
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}
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pub fn each_gen_bit_frozen(&self,
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id: ast::NodeId,
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f: &fn(uint) -> bool) -> bool {
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//! Iterates through each bit in the gen set for `id`.
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if !self.nodeid_to_bitset.contains_key(&id) {
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return true;
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}
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let (start, end) = self.compute_id_range_frozen(id);
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let gens = self.gens.slice(start, end);
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debug!("each_gen_bit(id={:?}, gens={})",
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id, bits_to_str(gens));
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self.each_bit(gens, f)
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}
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fn each_bit(&self,
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words: &[uint],
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f: &fn(uint) -> bool) -> bool {
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//! Helper for iterating over the bits in a bit set.
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for (word_index, &word) in words.iter().enumerate() {
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if word != 0 {
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let base_index = word_index * uint::bits;
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for offset in range(0u, uint::bits) {
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let bit = 1 << offset;
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if (word & bit) != 0 {
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// NB: we round up the total number of bits
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// that we store in any given bit set so that
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// it is an even multiple of uint::bits. This
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// means that there may be some stray bits at
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// the end that do not correspond to any
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// actual value. So before we callback, check
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// whether the bit_index is greater than the
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// actual value the user specified and stop
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// iterating if so.
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let bit_index = base_index + offset;
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if bit_index >= self.bits_per_id {
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return true;
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} else if !f(bit_index) {
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return false;
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}
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}
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}
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}
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}
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return true;
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}
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}
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impl<O:DataFlowOperator+Clone+'static> DataFlowContext<O> {
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// ^^^^^^^^^^^^^ only needed for pretty printing
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pub fn propagate(&mut self, blk: &ast::Block) {
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//! Performs the data flow analysis.
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if self.bits_per_id == 0 {
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// Optimize the surprisingly common degenerate case.
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return;
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}
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{
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let mut propcx = PropagationContext {
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dfcx: self,
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changed: true
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};
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let mut temp = vec::from_elem(self.words_per_id, 0u);
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let mut loop_scopes = ~[];
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while propcx.changed {
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propcx.changed = false;
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propcx.reset(temp);
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propcx.walk_block(blk, temp, &mut loop_scopes);
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}
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}
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debug!("Dataflow result:");
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debug!("{}", {
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let this = @(*self).clone();
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this.pretty_print_to(@mut io::stderr() as @mut io::Writer, blk);
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""
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});
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}
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fn pretty_print_to(@self, wr: @mut io::Writer, blk: &ast::Block) {
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let ps = pprust::rust_printer_annotated(wr,
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self.tcx.sess.intr(),
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self as @pprust::pp_ann);
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pprust::cbox(ps, pprust::indent_unit);
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pprust::ibox(ps, 0u);
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pprust::print_block(ps, blk);
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pp::eof(ps.s);
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}
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}
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impl<'self, O:DataFlowOperator> PropagationContext<'self, O> {
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fn tcx(&self) -> ty::ctxt {
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self.dfcx.tcx
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}
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fn walk_block(&mut self,
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blk: &ast::Block,
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in_out: &mut [uint],
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loop_scopes: &mut ~[LoopScope]) {
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debug!("DataFlowContext::walk_block(blk.id={:?}, in_out={})",
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blk.id, bits_to_str(reslice(in_out)));
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self.merge_with_entry_set(blk.id, in_out);
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for &stmt in blk.stmts.iter() {
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self.walk_stmt(stmt, in_out, loop_scopes);
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}
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self.walk_opt_expr(blk.expr, in_out, loop_scopes);
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self.dfcx.apply_gen_kill(blk.id, in_out);
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}
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fn walk_stmt(&mut self,
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stmt: @ast::Stmt,
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in_out: &mut [uint],
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loop_scopes: &mut ~[LoopScope]) {
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match stmt.node {
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ast::StmtDecl(decl, _) => {
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self.walk_decl(decl, in_out, loop_scopes);
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}
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ast::StmtExpr(expr, _) | ast::StmtSemi(expr, _) => {
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self.walk_expr(expr, in_out, loop_scopes);
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}
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ast::StmtMac(*) => {
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self.tcx().sess.span_bug(stmt.span, "unexpanded macro");
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}
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}
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}
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fn walk_decl(&mut self,
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decl: @ast::Decl,
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in_out: &mut [uint],
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loop_scopes: &mut ~[LoopScope]) {
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match decl.node {
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ast::DeclLocal(local) => {
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self.walk_opt_expr(local.init, in_out, loop_scopes);
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self.walk_pat(local.pat, in_out, loop_scopes);
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}
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ast::DeclItem(_) => {}
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}
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}
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fn walk_expr(&mut self,
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expr: &ast::Expr,
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in_out: &mut [uint],
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loop_scopes: &mut ~[LoopScope]) {
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debug!("DataFlowContext::walk_expr(expr={}, in_out={})",
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expr.repr(self.dfcx.tcx), bits_to_str(reslice(in_out)));
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self.merge_with_entry_set(expr.id, in_out);
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match expr.node {
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ast::ExprFnBlock(ref decl, ref body) |
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ast::ExprProc(ref decl, ref body) => {
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if self.dfcx.oper.walk_closures() {
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// In the absence of once fns, we must assume that
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// every function body will execute more than
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// once. Thus we treat every function body like a
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// loop.
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//
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// What is subtle and a bit tricky, also, is how
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// to deal with the "output" bits---that is, what
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// do we consider to be the successor of a
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// function body, given that it could be called
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// from any point within its lifetime? What we do
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// is to add their effects immediately as of the
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// point of creation. Of course we have to ensure
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// that this is sound for the analyses which make
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// use of dataflow.
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//
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// In the case of the initedness checker (which
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// does not currently use dataflow, but I hope to
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// convert at some point), we will simply not walk
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// closures at all, so it's a moot point.
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//
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// In the case of the borrow checker, this means
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// the loans which would be created by calling a
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// function come into effect immediately when the
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// function is created. This is guaranteed to be
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// earlier than the point at which the loan
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// actually comes into scope (which is the point
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// at which the closure is *called*). Because
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// loans persist until the scope of the loans is
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// exited, it is always a safe approximation to
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// have a loan begin earlier than it actually will
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// at runtime, so this should be sound.
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//
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// We stil have to be careful in the region
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// checker and borrow checker to treat function
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// bodies like loops, which implies some
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// limitations. For example, a closure cannot root
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// a managed box for longer than its body.
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//
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// General control flow looks like this:
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//
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// +- (expr) <----------+
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// | | |
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// | v |
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// | (body) -----------+--> (exit)
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// | | |
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// | + (break/loop) -+
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// | |
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// +--------------------+
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//
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// This is a bit more conservative than a loop.
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// Note that we must assume that even after a
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// `break` occurs (e.g., in a `for` loop) that the
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// closure may be reinvoked.
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|
//
|
|
// One difference from other loops is that `loop`
|
|
// and `break` statements which target a closure
|
|
// both simply add to the `break_bits`.
|
|
|
|
// func_bits represents the state when the function
|
|
// returns
|
|
let mut func_bits = reslice(in_out).to_owned();
|
|
|
|
loop_scopes.push(LoopScope {
|
|
loop_id: expr.id,
|
|
break_bits: reslice(in_out).to_owned()
|
|
});
|
|
for input in decl.inputs.iter() {
|
|
self.walk_pat(input.pat, func_bits, loop_scopes);
|
|
}
|
|
self.walk_block(body, func_bits, loop_scopes);
|
|
|
|
// add the bits from any early return via `break`,
|
|
// `continue`, or `return` into `func_bits`
|
|
let loop_scope = loop_scopes.pop();
|
|
join_bits(&self.dfcx.oper, loop_scope.break_bits, func_bits);
|
|
|
|
// add `func_bits` to the entry bits for `expr`,
|
|
// since we must assume the function may be called
|
|
// more than once
|
|
self.add_to_entry_set(expr.id, reslice(func_bits));
|
|
|
|
// the final exit bits include whatever was present
|
|
// in the original, joined with the bits from the function
|
|
join_bits(&self.dfcx.oper, func_bits, in_out);
|
|
}
|
|
}
|
|
|
|
ast::ExprIf(cond, ref then, els) => {
|
|
//
|
|
// (cond)
|
|
// |
|
|
// v
|
|
// ( )
|
|
// / \
|
|
// | |
|
|
// v v
|
|
// (then)(els)
|
|
// | |
|
|
// v v
|
|
// ( succ )
|
|
//
|
|
self.walk_expr(cond, in_out, loop_scopes);
|
|
|
|
let mut then_bits = reslice(in_out).to_owned();
|
|
self.walk_block(then, then_bits, loop_scopes);
|
|
|
|
self.walk_opt_expr(els, in_out, loop_scopes);
|
|
join_bits(&self.dfcx.oper, then_bits, in_out);
|
|
}
|
|
|
|
ast::ExprWhile(cond, ref blk) => {
|
|
//
|
|
// (expr) <--+
|
|
// | |
|
|
// v |
|
|
// +--(cond) |
|
|
// | | |
|
|
// | v |
|
|
// v (blk) ----+
|
|
// |
|
|
// <--+ (break)
|
|
//
|
|
|
|
self.walk_expr(cond, in_out, loop_scopes);
|
|
|
|
let mut body_bits = reslice(in_out).to_owned();
|
|
loop_scopes.push(LoopScope {
|
|
loop_id: expr.id,
|
|
break_bits: reslice(in_out).to_owned()
|
|
});
|
|
self.walk_block(blk, body_bits, loop_scopes);
|
|
self.add_to_entry_set(expr.id, body_bits);
|
|
let new_loop_scope = loop_scopes.pop();
|
|
copy_bits(new_loop_scope.break_bits, in_out);
|
|
}
|
|
|
|
ast::ExprForLoop(*) => fail!("non-desugared expr_for_loop"),
|
|
|
|
ast::ExprLoop(ref blk, _) => {
|
|
//
|
|
// (expr) <--+
|
|
// | |
|
|
// v |
|
|
// (blk) ----+
|
|
// |
|
|
// <--+ (break)
|
|
//
|
|
|
|
let mut body_bits = reslice(in_out).to_owned();
|
|
self.reset(in_out);
|
|
loop_scopes.push(LoopScope {
|
|
loop_id: expr.id,
|
|
break_bits: reslice(in_out).to_owned()
|
|
});
|
|
self.walk_block(blk, body_bits, loop_scopes);
|
|
self.add_to_entry_set(expr.id, body_bits);
|
|
|
|
let new_loop_scope = loop_scopes.pop();
|
|
assert_eq!(new_loop_scope.loop_id, expr.id);
|
|
copy_bits(new_loop_scope.break_bits, in_out);
|
|
}
|
|
|
|
ast::ExprMatch(discr, ref arms) => {
|
|
//
|
|
// (discr)
|
|
// / | \
|
|
// | | |
|
|
// v v v
|
|
// (..arms..)
|
|
// | | |
|
|
// v v v
|
|
// ( succ )
|
|
//
|
|
//
|
|
self.walk_expr(discr, in_out, loop_scopes);
|
|
|
|
let mut guards = reslice(in_out).to_owned();
|
|
|
|
// We know that exactly one arm will be taken, so we
|
|
// can start out with a blank slate and just union
|
|
// together the bits from each arm:
|
|
self.reset(in_out);
|
|
|
|
for arm in arms.iter() {
|
|
// in_out reflects the discr and all guards to date
|
|
self.walk_opt_expr(arm.guard, guards, loop_scopes);
|
|
|
|
// determine the bits for the body and then union
|
|
// them into `in_out`, which reflects all bodies to date
|
|
let mut body = reslice(guards).to_owned();
|
|
self.walk_pat_alternatives(arm.pats, body, loop_scopes);
|
|
self.walk_block(&arm.body, body, loop_scopes);
|
|
join_bits(&self.dfcx.oper, body, in_out);
|
|
}
|
|
}
|
|
|
|
ast::ExprRet(o_e) => {
|
|
self.walk_opt_expr(o_e, in_out, loop_scopes);
|
|
self.reset(in_out);
|
|
}
|
|
|
|
ast::ExprBreak(label) => {
|
|
let scope = self.find_scope(expr, label, loop_scopes);
|
|
self.break_from_to(expr, scope, in_out);
|
|
self.reset(in_out);
|
|
}
|
|
|
|
ast::ExprAgain(label) => {
|
|
let scope = self.find_scope(expr, label, loop_scopes);
|
|
self.pop_scopes(expr, scope, in_out);
|
|
self.add_to_entry_set(scope.loop_id, reslice(in_out));
|
|
self.reset(in_out);
|
|
}
|
|
|
|
ast::ExprAssign(l, r) |
|
|
ast::ExprAssignOp(_, _, l, r) => {
|
|
self.walk_expr(r, in_out, loop_scopes);
|
|
self.walk_expr(l, in_out, loop_scopes);
|
|
}
|
|
|
|
ast::ExprVec(ref exprs, _) => {
|
|
self.walk_exprs(*exprs, in_out, loop_scopes)
|
|
}
|
|
|
|
ast::ExprRepeat(l, r, _) => {
|
|
self.walk_expr(l, in_out, loop_scopes);
|
|
self.walk_expr(r, in_out, loop_scopes);
|
|
}
|
|
|
|
ast::ExprStruct(_, ref fields, with_expr) => {
|
|
for field in fields.iter() {
|
|
self.walk_expr(field.expr, in_out, loop_scopes);
|
|
}
|
|
self.walk_opt_expr(with_expr, in_out, loop_scopes);
|
|
}
|
|
|
|
ast::ExprCall(f, ref args, _) => {
|
|
self.walk_call(f.id, expr.id,
|
|
f, *args, in_out, loop_scopes);
|
|
}
|
|
|
|
ast::ExprMethodCall(callee_id, rcvr, _, _, ref args, _) => {
|
|
self.walk_call(callee_id, expr.id,
|
|
rcvr, *args, in_out, loop_scopes);
|
|
}
|
|
|
|
ast::ExprIndex(callee_id, l, r) |
|
|
ast::ExprBinary(callee_id, _, l, r) if self.is_method_call(expr) => {
|
|
self.walk_call(callee_id, expr.id,
|
|
l, [r], in_out, loop_scopes);
|
|
}
|
|
|
|
ast::ExprUnary(callee_id, _, e) if self.is_method_call(expr) => {
|
|
self.walk_call(callee_id, expr.id,
|
|
e, [], in_out, loop_scopes);
|
|
}
|
|
|
|
ast::ExprTup(ref exprs) => {
|
|
self.walk_exprs(*exprs, in_out, loop_scopes);
|
|
}
|
|
|
|
ast::ExprBinary(_, op, l, r) if ast_util::lazy_binop(op) => {
|
|
self.walk_expr(l, in_out, loop_scopes);
|
|
let temp = reslice(in_out).to_owned();
|
|
self.walk_expr(r, in_out, loop_scopes);
|
|
join_bits(&self.dfcx.oper, temp, in_out);
|
|
}
|
|
|
|
ast::ExprIndex(_, l, r) |
|
|
ast::ExprBinary(_, _, l, r) => {
|
|
self.walk_exprs([l, r], in_out, loop_scopes);
|
|
}
|
|
|
|
ast::ExprLogLevel |
|
|
ast::ExprLit(*) |
|
|
ast::ExprPath(*) |
|
|
ast::ExprSelf => {
|
|
}
|
|
|
|
ast::ExprAddrOf(_, e) |
|
|
ast::ExprDoBody(e) |
|
|
ast::ExprCast(e, _) |
|
|
ast::ExprUnary(_, _, e) |
|
|
ast::ExprParen(e) |
|
|
ast::ExprVstore(e, _) |
|
|
ast::ExprField(e, _, _) => {
|
|
self.walk_expr(e, in_out, loop_scopes);
|
|
}
|
|
|
|
ast::ExprInlineAsm(ref inline_asm) => {
|
|
for &(_, expr) in inline_asm.inputs.iter() {
|
|
self.walk_expr(expr, in_out, loop_scopes);
|
|
}
|
|
for &(_, expr) in inline_asm.outputs.iter() {
|
|
self.walk_expr(expr, in_out, loop_scopes);
|
|
}
|
|
}
|
|
|
|
ast::ExprBlock(ref blk) => {
|
|
self.walk_block(blk, in_out, loop_scopes);
|
|
}
|
|
|
|
ast::ExprMac(*) => {
|
|
self.tcx().sess.span_bug(expr.span, "unexpanded macro");
|
|
}
|
|
}
|
|
|
|
self.dfcx.apply_gen_kill(expr.id, in_out);
|
|
}
|
|
|
|
fn pop_scopes(&mut self,
|
|
from_expr: &ast::Expr,
|
|
to_scope: &mut LoopScope,
|
|
in_out: &mut [uint]) {
|
|
//! Whenever you have a `break` or a `loop` statement, flow
|
|
//! exits through any number of enclosing scopes on its
|
|
//! way to the new destination. This function applies the kill
|
|
//! sets of those enclosing scopes to `in_out` (those kill sets
|
|
//! concern items that are going out of scope).
|
|
|
|
let tcx = self.tcx();
|
|
let region_maps = tcx.region_maps;
|
|
|
|
debug!("pop_scopes(from_expr={}, to_scope={:?}, in_out={})",
|
|
from_expr.repr(tcx), to_scope.loop_id,
|
|
bits_to_str(reslice(in_out)));
|
|
|
|
let mut id = from_expr.id;
|
|
while id != to_scope.loop_id {
|
|
self.dfcx.apply_kill(id, in_out);
|
|
|
|
match region_maps.opt_encl_scope(id) {
|
|
Some(i) => { id = i; }
|
|
None => {
|
|
tcx.sess.span_bug(
|
|
from_expr.span,
|
|
format!("pop_scopes(from_expr={}, to_scope={:?}) \
|
|
to_scope does not enclose from_expr",
|
|
from_expr.repr(tcx), to_scope.loop_id));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn break_from_to(&mut self,
|
|
from_expr: &ast::Expr,
|
|
to_scope: &mut LoopScope,
|
|
in_out: &mut [uint]) {
|
|
self.pop_scopes(from_expr, to_scope, in_out);
|
|
self.dfcx.apply_kill(from_expr.id, in_out);
|
|
join_bits(&self.dfcx.oper, reslice(in_out), to_scope.break_bits);
|
|
debug!("break_from_to(from_expr={}, to_scope={:?}) final break_bits={}",
|
|
from_expr.repr(self.tcx()),
|
|
to_scope.loop_id,
|
|
bits_to_str(reslice(in_out)));
|
|
}
|
|
|
|
fn walk_exprs(&mut self,
|
|
exprs: &[@ast::Expr],
|
|
in_out: &mut [uint],
|
|
loop_scopes: &mut ~[LoopScope]) {
|
|
for &expr in exprs.iter() {
|
|
self.walk_expr(expr, in_out, loop_scopes);
|
|
}
|
|
}
|
|
|
|
fn walk_opt_expr(&mut self,
|
|
opt_expr: Option<@ast::Expr>,
|
|
in_out: &mut [uint],
|
|
loop_scopes: &mut ~[LoopScope]) {
|
|
for &expr in opt_expr.iter() {
|
|
self.walk_expr(expr, in_out, loop_scopes);
|
|
}
|
|
}
|
|
|
|
fn walk_call(&mut self,
|
|
_callee_id: ast::NodeId,
|
|
call_id: ast::NodeId,
|
|
arg0: &ast::Expr,
|
|
args: &[@ast::Expr],
|
|
in_out: &mut [uint],
|
|
loop_scopes: &mut ~[LoopScope]) {
|
|
self.walk_expr(arg0, in_out, loop_scopes);
|
|
self.walk_exprs(args, in_out, loop_scopes);
|
|
|
|
// FIXME(#6268) nested method calls
|
|
// self.merge_with_entry_set(callee_id, in_out);
|
|
// self.dfcx.apply_gen_kill(callee_id, in_out);
|
|
|
|
let return_ty = ty::node_id_to_type(self.tcx(), call_id);
|
|
let fails = ty::type_is_bot(return_ty);
|
|
if fails {
|
|
self.reset(in_out);
|
|
}
|
|
}
|
|
|
|
fn walk_pat(&mut self,
|
|
pat: @ast::Pat,
|
|
in_out: &mut [uint],
|
|
_loop_scopes: &mut ~[LoopScope]) {
|
|
debug!("DataFlowContext::walk_pat(pat={}, in_out={})",
|
|
pat.repr(self.dfcx.tcx), bits_to_str(reslice(in_out)));
|
|
|
|
do ast_util::walk_pat(pat) |p| {
|
|
debug!(" p.id={:?} in_out={}", p.id, bits_to_str(reslice(in_out)));
|
|
self.merge_with_entry_set(p.id, in_out);
|
|
self.dfcx.apply_gen_kill(p.id, in_out);
|
|
true
|
|
};
|
|
}
|
|
|
|
fn walk_pat_alternatives(&mut self,
|
|
pats: &[@ast::Pat],
|
|
in_out: &mut [uint],
|
|
loop_scopes: &mut ~[LoopScope]) {
|
|
if pats.len() == 1 {
|
|
// Common special case:
|
|
return self.walk_pat(pats[0], in_out, loop_scopes);
|
|
}
|
|
|
|
// In the general case, the patterns in `pats` are
|
|
// alternatives, so we must treat this like an N-way select
|
|
// statement.
|
|
let initial_state = reslice(in_out).to_owned();
|
|
for &pat in pats.iter() {
|
|
let mut temp = initial_state.clone();
|
|
self.walk_pat(pat, temp, loop_scopes);
|
|
join_bits(&self.dfcx.oper, temp, in_out);
|
|
}
|
|
}
|
|
|
|
fn find_scope<'a>(&self,
|
|
expr: &ast::Expr,
|
|
label: Option<ast::Name>,
|
|
loop_scopes: &'a mut ~[LoopScope]) -> &'a mut LoopScope {
|
|
let index = match label {
|
|
None => {
|
|
let len = loop_scopes.len();
|
|
len - 1
|
|
}
|
|
|
|
Some(_) => {
|
|
match self.tcx().def_map.find(&expr.id) {
|
|
Some(&ast::DefLabel(loop_id)) => {
|
|
match loop_scopes.iter().position(|l| l.loop_id == loop_id) {
|
|
Some(i) => i,
|
|
None => {
|
|
self.tcx().sess.span_bug(
|
|
expr.span,
|
|
format!("No loop scope for id {:?}", loop_id));
|
|
}
|
|
}
|
|
}
|
|
|
|
r => {
|
|
self.tcx().sess.span_bug(
|
|
expr.span,
|
|
format!("Bad entry `{:?}` in def_map for label", r));
|
|
}
|
|
}
|
|
}
|
|
};
|
|
|
|
&mut loop_scopes[index]
|
|
}
|
|
|
|
fn is_method_call(&self, expr: &ast::Expr) -> bool {
|
|
self.dfcx.method_map.contains_key(&expr.id)
|
|
}
|
|
|
|
fn reset(&mut self, bits: &mut [uint]) {
|
|
let e = if self.dfcx.oper.initial_value() {uint::max_value} else {0};
|
|
for b in bits.mut_iter() { *b = e; }
|
|
}
|
|
|
|
fn add_to_entry_set(&mut self, id: ast::NodeId, pred_bits: &[uint]) {
|
|
debug!("add_to_entry_set(id={:?}, pred_bits={})",
|
|
id, bits_to_str(pred_bits));
|
|
let (start, end) = self.dfcx.compute_id_range(id);
|
|
let changed = { // FIXME(#5074) awkward construction
|
|
let on_entry = self.dfcx.on_entry.mut_slice(start, end);
|
|
join_bits(&self.dfcx.oper, pred_bits, on_entry)
|
|
};
|
|
if changed {
|
|
debug!("changed entry set for {:?} to {}",
|
|
id, bits_to_str(self.dfcx.on_entry.slice(start, end)));
|
|
self.changed = true;
|
|
}
|
|
}
|
|
|
|
fn merge_with_entry_set(&mut self,
|
|
id: ast::NodeId,
|
|
pred_bits: &mut [uint]) {
|
|
debug!("merge_with_entry_set(id={:?}, pred_bits={})",
|
|
id, mut_bits_to_str(pred_bits));
|
|
let (start, end) = self.dfcx.compute_id_range(id);
|
|
let changed = { // FIXME(#5074) awkward construction
|
|
let on_entry = self.dfcx.on_entry.mut_slice(start, end);
|
|
let changed = join_bits(&self.dfcx.oper, reslice(pred_bits), on_entry);
|
|
copy_bits(reslice(on_entry), pred_bits);
|
|
changed
|
|
};
|
|
if changed {
|
|
debug!("changed entry set for {:?} to {}",
|
|
id, bits_to_str(self.dfcx.on_entry.slice(start, end)));
|
|
self.changed = true;
|
|
}
|
|
}
|
|
}
|
|
|
|
fn mut_bits_to_str(words: &mut [uint]) -> ~str {
|
|
bits_to_str(reslice(words))
|
|
}
|
|
|
|
fn bits_to_str(words: &[uint]) -> ~str {
|
|
let mut result = ~"";
|
|
let mut sep = '[';
|
|
|
|
// Note: this is a little endian printout of bytes.
|
|
|
|
for &word in words.iter() {
|
|
let mut v = word;
|
|
for _ in range(0u, uint::bytes) {
|
|
result.push_char(sep);
|
|
result.push_str(format!("{:02x}", v & 0xFF));
|
|
v >>= 8;
|
|
sep = '-';
|
|
}
|
|
}
|
|
result.push_char(']');
|
|
return result;
|
|
}
|
|
|
|
fn copy_bits(in_vec: &[uint], out_vec: &mut [uint]) -> bool {
|
|
bitwise(out_vec, in_vec, |_, b| b)
|
|
}
|
|
|
|
fn join_bits<O:DataFlowOperator>(oper: &O,
|
|
in_vec: &[uint],
|
|
out_vec: &mut [uint]) -> bool {
|
|
bitwise(out_vec, in_vec, |a, b| oper.join(a, b))
|
|
}
|
|
|
|
#[inline]
|
|
fn bitwise(out_vec: &mut [uint],
|
|
in_vec: &[uint],
|
|
op: &fn(uint, uint) -> uint) -> bool {
|
|
assert_eq!(out_vec.len(), in_vec.len());
|
|
let mut changed = false;
|
|
for (out_elt, in_elt) in out_vec.mut_iter().zip(in_vec.iter()) {
|
|
let old_val = *out_elt;
|
|
let new_val = op(old_val, *in_elt);
|
|
*out_elt = new_val;
|
|
changed |= (old_val != new_val);
|
|
}
|
|
changed
|
|
}
|
|
|
|
fn set_bit(words: &mut [uint], bit: uint) -> bool {
|
|
debug!("set_bit: words={} bit={}",
|
|
mut_bits_to_str(words), bit_str(bit));
|
|
let word = bit / uint::bits;
|
|
let bit_in_word = bit % uint::bits;
|
|
let bit_mask = 1 << bit_in_word;
|
|
debug!("word={} bit_in_word={} bit_mask={}", word, bit_in_word, word);
|
|
let oldv = words[word];
|
|
let newv = oldv | bit_mask;
|
|
words[word] = newv;
|
|
oldv != newv
|
|
}
|
|
|
|
fn bit_str(bit: uint) -> ~str {
|
|
let byte = bit >> 8;
|
|
let lobits = 1 << (bit & 0xFF);
|
|
format!("[{}:{}-{:02x}]", bit, byte, lobits)
|
|
}
|
|
|
|
fn reslice<'a>(v: &'a mut [uint]) -> &'a [uint] {
|
|
// bFIXME(#5074) this function should not be necessary at all
|
|
unsafe {
|
|
cast::transmute(v)
|
|
}
|
|
}
|