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use rustc_data_structures::indexed_set::{IdxSet, IdxSetBuf};
use rustc_data_structures::indexed_vec::Idx;
use rustc_data_structures::bitslice::{bitwise, BitwiseOperator};
use rustc::ty::TyCtxt;
use rustc::mir::{self, Mir};
use std::fmt::Debug;
use std::io;
use std::mem;
use std::path::PathBuf;
use std::usize;
use super::MirBorrowckCtxtPreDataflow;
pub use self::sanity_check::sanity_check_via_rustc_peek;
pub use self::impls::{MaybeInitializedLvals, MaybeUninitializedLvals};
pub use self::impls::{DefinitelyInitializedLvals, MovingOutStatements};
mod graphviz;
mod sanity_check;
mod impls;
pub trait Dataflow<BD: BitDenotation> {
fn dataflow<P>(&mut self, p: P) where P: Fn(&BD, BD::Idx) -> &Debug;
}
impl<'a, 'tcx: 'a, BD> Dataflow<BD> for MirBorrowckCtxtPreDataflow<'a, 'tcx, BD>
where BD: BitDenotation + DataflowOperator
{
fn dataflow<P>(&mut self, p: P) where P: Fn(&BD, BD::Idx) -> &Debug {
self.flow_state.build_sets();
self.pre_dataflow_instrumentation(|c,i| p(c,i)).unwrap();
self.flow_state.propagate();
self.post_dataflow_instrumentation(|c,i| p(c,i)).unwrap();
}
}
struct PropagationContext<'b, 'a: 'b, 'tcx: 'a, O>
where O: 'b + BitDenotation
{
builder: &'b mut DataflowAnalysis<'a, 'tcx, O>,
changed: bool,
}
impl<'a, 'tcx: 'a, BD> DataflowAnalysis<'a, 'tcx, BD>
where BD: BitDenotation + DataflowOperator
{
fn propagate(&mut self) {
let mut temp = IdxSetBuf::new_empty(self.flow_state.sets.bits_per_block);
let mut propcx = PropagationContext {
builder: self,
changed: true,
};
while propcx.changed {
propcx.changed = false;
propcx.reset(&mut temp);
propcx.walk_cfg(&mut temp);
}
}
fn build_sets(&mut self) {
{
let sets = &mut self.flow_state.sets.for_block(mir::START_BLOCK.index());
self.flow_state.operator.start_block_effect(sets);
}
for (bb, data) in self.mir.basic_blocks().iter_enumerated() {
let &mir::BasicBlockData { ref statements, ref terminator, is_cleanup: _ } = data;
let sets = &mut self.flow_state.sets.for_block(bb.index());
for j_stmt in 0..statements.len() {
self.flow_state.operator.statement_effect(sets, bb, j_stmt);
}
if terminator.is_some() {
let stmts_len = statements.len();
self.flow_state.operator.terminator_effect(sets, bb, stmts_len);
}
}
}
}
impl<'b, 'a: 'b, 'tcx: 'a, BD> PropagationContext<'b, 'a, 'tcx, BD>
where BD: BitDenotation + DataflowOperator
{
fn reset(&mut self, bits: &mut IdxSet<BD::Idx>) {
let e = if BD::bottom_value() {!0} else {0};
for b in bits.words_mut() {
*b = e;
}
}
fn walk_cfg(&mut self, in_out: &mut IdxSet<BD::Idx>) {
let mir = self.builder.mir;
for (bb_idx, bb_data) in mir.basic_blocks().iter().enumerate() {
let builder = &mut self.builder;
{
let sets = builder.flow_state.sets.for_block(bb_idx);
debug_assert!(in_out.words().len() == sets.on_entry.words().len());
in_out.clone_from(sets.on_entry);
in_out.union(sets.gen_set);
in_out.subtract(sets.kill_set);
}
builder.propagate_bits_into_graph_successors_of(
in_out, &mut self.changed, (mir::BasicBlock::new(bb_idx), bb_data));
}
}
}
fn dataflow_path(context: &str, prepost: &str, path: &str) -> PathBuf {
format!("{}_{}", context, prepost);
let mut path = PathBuf::from(path);
let new_file_name = {
let orig_file_name = path.file_name().unwrap().to_str().unwrap();
format!("{}_{}", context, orig_file_name)
};
path.set_file_name(new_file_name);
path
}
impl<'a, 'tcx: 'a, BD> MirBorrowckCtxtPreDataflow<'a, 'tcx, BD>
where BD: BitDenotation
{
fn pre_dataflow_instrumentation<P>(&self, p: P) -> io::Result<()>
where P: Fn(&BD, BD::Idx) -> &Debug
{
if let Some(ref path_str) = self.print_preflow_to {
let path = dataflow_path(BD::name(), "preflow", path_str);
graphviz::print_borrowck_graph_to(self, &path, p)
} else {
Ok(())
}
}
fn post_dataflow_instrumentation<P>(&self, p: P) -> io::Result<()>
where P: Fn(&BD, BD::Idx) -> &Debug
{
if let Some(ref path_str) = self.print_postflow_to {
let path = dataflow_path(BD::name(), "postflow", path_str);
graphviz::print_borrowck_graph_to(self, &path, p)
} else{
Ok(())
}
}
}
#[derive(Debug)]
struct Bits<E:Idx> {
bits: IdxSetBuf<E>,
}
impl<E:Idx> Clone for Bits<E> {
fn clone(&self) -> Self { Bits { bits: self.bits.clone() } }
}
impl<E:Idx> Bits<E> {
fn new(bits: IdxSetBuf<E>) -> Self {
Bits { bits: bits }
}
}
pub struct DataflowAnalysis<'a, 'tcx: 'a, O>
where O: BitDenotation
{
flow_state: DataflowState<O>,
mir: &'a Mir<'tcx>,
}
impl<'a, 'tcx: 'a, O> DataflowAnalysis<'a, 'tcx, O>
where O: BitDenotation
{
pub fn results(self) -> DataflowResults<O> {
DataflowResults(self.flow_state)
}
pub fn mir(&self) -> &'a Mir<'tcx> { self.mir }
}
pub struct DataflowResults<O>(DataflowState<O>) where O: BitDenotation;
impl<O: BitDenotation> DataflowResults<O> {
pub fn sets(&self) -> &AllSets<O::Idx> {
&self.0.sets
}
}
pub struct DataflowState<O: BitDenotation>
{
pub sets: AllSets<O::Idx>,
operator: O,
}
#[derive(Debug)]
pub struct AllSets<E: Idx> {
bits_per_block: usize,
words_per_block: usize,
gen_sets: Bits<E>,
kill_sets: Bits<E>,
on_entry_sets: Bits<E>,
}
pub struct BlockSets<'a, E: Idx> {
on_entry: &'a mut IdxSet<E>,
gen_set: &'a mut IdxSet<E>,
kill_set: &'a mut IdxSet<E>,
}
impl<'a, E:Idx> BlockSets<'a, E> {
fn gen(&mut self, e: &E) {
self.gen_set.add(e);
self.kill_set.remove(e);
}
fn kill(&mut self, e: &E) {
self.gen_set.remove(e);
self.kill_set.add(e);
}
}
impl<E:Idx> AllSets<E> {
pub fn bits_per_block(&self) -> usize { self.bits_per_block }
pub fn for_block(&mut self, block_idx: usize) -> BlockSets<E> {
let offset = self.words_per_block * block_idx;
let range = E::new(offset)..E::new(offset + self.words_per_block);
BlockSets {
on_entry: self.on_entry_sets.bits.range_mut(&range),
gen_set: self.gen_sets.bits.range_mut(&range),
kill_set: self.kill_sets.bits.range_mut(&range),
}
}
fn lookup_set_for<'a>(&self, sets: &'a Bits<E>, block_idx: usize) -> &'a IdxSet<E> {
let offset = self.words_per_block * block_idx;
let range = E::new(offset)..E::new(offset + self.words_per_block);
sets.bits.range(&range)
}
pub fn gen_set_for(&self, block_idx: usize) -> &IdxSet<E> {
self.lookup_set_for(&self.gen_sets, block_idx)
}
pub fn kill_set_for(&self, block_idx: usize) -> &IdxSet<E> {
self.lookup_set_for(&self.kill_sets, block_idx)
}
pub fn on_entry_set_for(&self, block_idx: usize) -> &IdxSet<E> {
self.lookup_set_for(&self.on_entry_sets, block_idx)
}
}
pub trait DataflowOperator: BitwiseOperator {
fn bottom_value() -> bool;
}
pub trait BitDenotation {
type Idx: Idx;
fn name() -> &'static str;
fn bits_per_block(&self) -> usize;
fn start_block_effect(&self, sets: &mut BlockSets<Self::Idx>);
fn statement_effect(&self,
sets: &mut BlockSets<Self::Idx>,
bb: mir::BasicBlock,
idx_stmt: usize);
fn terminator_effect(&self,
sets: &mut BlockSets<Self::Idx>,
bb: mir::BasicBlock,
idx_term: usize);
fn propagate_call_return(&self,
in_out: &mut IdxSet<Self::Idx>,
call_bb: mir::BasicBlock,
dest_bb: mir::BasicBlock,
dest_lval: &mir::Lvalue);
}
impl<'a, 'tcx: 'a, D> DataflowAnalysis<'a, 'tcx, D>
where D: BitDenotation + DataflowOperator
{
pub fn new(_tcx: TyCtxt<'a, 'tcx, 'tcx>,
mir: &'a Mir<'tcx>,
denotation: D) -> Self {
let bits_per_block = denotation.bits_per_block();
let usize_bits = mem::size_of::<usize>() * 8;
let words_per_block = (bits_per_block + usize_bits - 1) / usize_bits;
let bits_per_block = words_per_block * usize_bits;
let num_blocks = mir.basic_blocks().len();
let num_overall = num_blocks * bits_per_block;
let zeroes = Bits::new(IdxSetBuf::new_empty(num_overall));
let on_entry = Bits::new(if D::bottom_value() {
IdxSetBuf::new_filled(num_overall)
} else {
IdxSetBuf::new_empty(num_overall)
});
DataflowAnalysis {
mir: mir,
flow_state: DataflowState {
sets: AllSets {
bits_per_block: bits_per_block,
words_per_block: words_per_block,
gen_sets: zeroes.clone(),
kill_sets: zeroes,
on_entry_sets: on_entry,
},
operator: denotation,
},
}
}
}
impl<'a, 'tcx: 'a, D> DataflowAnalysis<'a, 'tcx, D>
where D: BitDenotation + DataflowOperator
{
fn propagate_bits_into_graph_successors_of(
&mut self,
in_out: &mut IdxSet<D::Idx>,
changed: &mut bool,
(bb, bb_data): (mir::BasicBlock, &mir::BasicBlockData))
{
match bb_data.terminator().kind {
mir::TerminatorKind::Return |
mir::TerminatorKind::Resume |
mir::TerminatorKind::Unreachable => {}
mir::TerminatorKind::Goto { ref target } |
mir::TerminatorKind::Assert { ref target, cleanup: None, .. } |
mir::TerminatorKind::Drop { ref target, location: _, unwind: None } |
mir::TerminatorKind::DropAndReplace {
ref target, value: _, location: _, unwind: None
} => {
self.propagate_bits_into_entry_set_for(in_out, changed, target);
}
mir::TerminatorKind::Assert { ref target, cleanup: Some(ref unwind), .. } |
mir::TerminatorKind::Drop { ref target, location: _, unwind: Some(ref unwind) } |
mir::TerminatorKind::DropAndReplace {
ref target, value: _, location: _, unwind: Some(ref unwind)
} => {
self.propagate_bits_into_entry_set_for(in_out, changed, target);
self.propagate_bits_into_entry_set_for(in_out, changed, unwind);
}
mir::TerminatorKind::SwitchInt { ref targets, .. } => {
for target in targets {
self.propagate_bits_into_entry_set_for(in_out, changed, target);
}
}
mir::TerminatorKind::Call { ref cleanup, ref destination, func: _, args: _ } => {
if let Some(ref unwind) = *cleanup {
self.propagate_bits_into_entry_set_for(in_out, changed, unwind);
}
if let Some((ref dest_lval, ref dest_bb)) = *destination {
self.flow_state.operator.propagate_call_return(
in_out, bb, *dest_bb, dest_lval);
self.propagate_bits_into_entry_set_for(in_out, changed, dest_bb);
}
}
}
}
fn propagate_bits_into_entry_set_for(&mut self,
in_out: &IdxSet<D::Idx>,
changed: &mut bool,
bb: &mir::BasicBlock) {
let entry_set = self.flow_state.sets.for_block(bb.index()).on_entry;
let set_changed = bitwise(entry_set.words_mut(),
in_out.words(),
&self.flow_state.operator);
if set_changed {
*changed = true;
}
}
}