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use crate::{
function_target::FunctionTarget,
stackless_bytecode::{Bytecode, Label},
};
use move_binary_format::file_format::CodeOffset;
use petgraph::{dot::Dot, graph::Graph};
use std::collections::{BTreeMap, BTreeSet};
type Map<K, V> = BTreeMap<K, V>;
type Set<V> = BTreeSet<V>;
pub type BlockId = CodeOffset;
#[derive(Debug)]
struct Block {
successors: Vec<BlockId>,
content: BlockContent,
}
#[derive(Copy, Clone, Debug)]
pub enum BlockContent {
Basic {
lower: CodeOffset,
upper: CodeOffset,
},
Dummy,
}
pub struct StacklessControlFlowGraph {
entry_block_id: BlockId,
blocks: Map<BlockId, Block>,
backward: bool,
}
const DUMMY_ENTRANCE: BlockId = 0;
const DUMMY_EXIT: BlockId = 1;
impl StacklessControlFlowGraph {
pub fn new_forward(code: &[Bytecode]) -> Self {
Self {
entry_block_id: DUMMY_ENTRANCE,
blocks: Self::collect_blocks(code),
backward: false,
}
}
pub fn new_backward(code: &[Bytecode], from_all_blocks: bool) -> Self {
let blocks = Self::collect_blocks(code);
let mut block_id_to_predecessors: Map<BlockId, Vec<BlockId>> =
blocks.keys().map(|block_id| (*block_id, vec![])).collect();
for (block_id, block) in &blocks {
for succ_block_id in &block.successors {
if from_all_blocks && *succ_block_id == DUMMY_EXIT {
continue;
}
let predecessors = &mut block_id_to_predecessors.get_mut(succ_block_id).unwrap();
predecessors.push(*block_id);
}
}
if from_all_blocks {
let predecessors = &mut block_id_to_predecessors.get_mut(&DUMMY_EXIT).unwrap();
blocks.keys().for_each(|block_id| {
if *block_id != DUMMY_ENTRANCE && *block_id != DUMMY_EXIT {
predecessors.push(*block_id);
}
});
}
Self {
entry_block_id: DUMMY_EXIT,
blocks: block_id_to_predecessors
.into_iter()
.map(|(block_id, predecessors)| {
(
block_id,
Block {
successors: predecessors,
content: blocks[&block_id].content,
},
)
})
.collect(),
backward: true,
}
}
fn collect_blocks(code: &[Bytecode]) -> Map<BlockId, Block> {
let label_offsets = Bytecode::label_offsets(code);
let mut bb_offsets = Set::new();
bb_offsets.insert(0);
for pc in 0..code.len() {
StacklessControlFlowGraph::record_block_ids(
pc as CodeOffset,
code,
&mut bb_offsets,
&label_offsets,
);
}
let mut blocks = Map::new();
let mut offset_to_key = Map::new();
let mut bcounter = 2;
let mut block_entry = 0;
for pc in 0..code.len() {
let co_pc: CodeOffset = pc as CodeOffset;
if StacklessControlFlowGraph::is_end_of_block(co_pc, code, &bb_offsets) {
let mut successors = Bytecode::get_successors(co_pc, code, &label_offsets);
for successor in successors.iter_mut() {
*successor = *offset_to_key.entry(*successor).or_insert(bcounter);
bcounter = std::cmp::max(*successor + 1, bcounter);
}
if code[co_pc as usize].is_exit() {
successors.push(DUMMY_EXIT);
}
let bb = BlockContent::Basic {
lower: block_entry,
upper: co_pc,
};
let key = *offset_to_key.entry(block_entry).or_insert(bcounter);
bcounter = std::cmp::max(key + 1, bcounter);
blocks.insert(
key,
Block {
successors,
content: bb,
},
);
block_entry = co_pc + 1;
}
}
assert_eq!(block_entry, code.len() as CodeOffset);
let entry_bb = *offset_to_key.get(&0).unwrap();
blocks.insert(
DUMMY_ENTRANCE,
Block {
successors: vec![entry_bb],
content: BlockContent::Dummy,
},
);
blocks.insert(
DUMMY_EXIT,
Block {
successors: Vec::new(),
content: BlockContent::Dummy,
},
);
blocks
}
fn is_end_of_block(pc: CodeOffset, code: &[Bytecode], block_ids: &Set<BlockId>) -> bool {
pc + 1 == (code.len() as CodeOffset) || block_ids.contains(&(pc + 1))
}
fn record_block_ids(
pc: CodeOffset,
code: &[Bytecode],
block_ids: &mut Set<BlockId>,
label_offsets: &BTreeMap<Label, CodeOffset>,
) {
let bytecode = &code[pc as usize];
for label in bytecode.branch_dests() {
block_ids.insert(*label_offsets.get(&label).unwrap());
}
if bytecode.is_branch() && pc + 1 < (code.len() as CodeOffset) {
block_ids.insert(pc + 1);
}
}
}
impl StacklessControlFlowGraph {
pub fn successors(&self, block_id: BlockId) -> &Vec<BlockId> {
&self.blocks[&block_id].successors
}
pub fn content(&self, block_id: BlockId) -> &BlockContent {
&self.blocks[&block_id].content
}
pub fn blocks(&self) -> Vec<BlockId> {
self.blocks.keys().cloned().collect()
}
pub fn entry_block(&self) -> BlockId {
self.entry_block_id
}
pub fn exit_block(&self) -> BlockId {
if self.backward {
DUMMY_ENTRANCE
} else {
DUMMY_EXIT
}
}
pub fn instr_indexes(
&self,
block_id: BlockId,
) -> Option<Box<dyn DoubleEndedIterator<Item = CodeOffset>>> {
match self.blocks[&block_id].content {
BlockContent::Basic { lower, upper } => Some(Box::new(lower..=upper)),
BlockContent::Dummy => None,
}
}
pub fn num_blocks(&self) -> u16 {
self.blocks.len() as u16
}
pub fn is_dummmy(&self, block_id: BlockId) -> bool {
matches!(self.blocks[&block_id].content, BlockContent::Dummy)
}
pub fn display(&self) {
println!("+=======================+");
println!("entry_block_id = {}", self.entry_block_id);
println!("blocks = {:?}", self.blocks);
println!("is_backward = {}", self.backward);
println!("+=======================+");
}
}
struct DotCFGBlock<'env> {
block_id: BlockId,
content: BlockContent,
func_target: &'env FunctionTarget<'env>,
label_offsets: BTreeMap<Label, CodeOffset>,
}
impl<'env> std::fmt::Display for DotCFGBlock<'env> {
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
let code_range = match self.content {
BlockContent::Basic { lower, upper } => format!("offset {}..={}", lower, upper),
BlockContent::Dummy => "X".to_owned(),
};
writeln!(f, "[Block {} - {}]", self.block_id, code_range)?;
match self.content {
BlockContent::Basic { lower, upper } => {
let code = &self.func_target.data.code;
for (offset, instruction) in
(lower..=upper).zip(&code[(lower as usize)..=(upper as usize)])
{
let text = self.func_target.pretty_print_bytecode(
&self.label_offsets,
offset as usize,
instruction,
);
writeln!(f, "{}", text)?;
}
}
BlockContent::Dummy => {}
}
Ok(())
}
}
struct DotCFGEdge {}
impl std::fmt::Display for DotCFGEdge {
fn fmt(&self, _f: &mut std::fmt::Formatter) -> std::fmt::Result {
Ok(())
}
}
pub fn generate_cfg_in_dot_format<'env>(func_target: &'env FunctionTarget<'env>) -> String {
let code = &func_target.data.code;
let cfg = StacklessControlFlowGraph::new_forward(code);
let label_offsets = Bytecode::label_offsets(code);
let mut graph = Graph::new();
let mut node_map = Map::new();
for (block_id, block) in &cfg.blocks {
let dot_block = DotCFGBlock {
block_id: *block_id,
content: block.content,
func_target,
label_offsets: label_offsets.clone(),
};
let node_index = graph.add_node(dot_block);
node_map.insert(block_id, node_index);
}
for (block_id, block) in &cfg.blocks {
for successor in &block.successors {
graph.add_edge(
*node_map.get(block_id).unwrap(),
*node_map.get(successor).unwrap(),
DotCFGEdge {},
);
}
}
format!(
"{}",
Dot::with_attr_getters(&graph, &[], &|_, _| "".to_string(), &|_, _| {
"shape=box".to_string()
})
)
}