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Fix loop contracts transformation when loops in branching #3640

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Merged
merged 2 commits into from
Oct 25, 2024
Merged

Fix loop contracts transformation when loops in branching #3640

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bd12d9d
Fix loop contracts transformation when loops in branching
qinheping Oct 24, 2024
1cd28b0
Merge branch 'main' into fix_bugs_in_loop_contracts_transformation
qinheping Oct 25, 2024
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10 changes: 6 additions & 4 deletions kani-compiler/src/kani_middle/transform/loop_contracts.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -114,7 +114,7 @@ impl TransformPass for LoopContractPass {
let mut loop_queue: VecDeque<BasicBlockIdx> = VecDeque::new();
queue.push_back(0);

while let Some(bb_idx) = queue.pop_front().or(loop_queue.pop_front()) {
while let Some(bb_idx) = queue.pop_front().or_else(|| loop_queue.pop_front()) {
visited.insert(bb_idx);

let terminator = new_body.blocks()[bb_idx].terminator.clone();
Expand All @@ -126,9 +126,11 @@ impl TransformPass for LoopContractPass {
// the visiting queue.
for to_visit in terminator.successors() {
if !visited.contains(&to_visit) {
let target_queue =
if is_loop_head { &mut loop_queue } else { &mut queue };
target_queue.push_back(to_visit);
if is_loop_head {
loop_queue.push_back(to_visit);
} else {
queue.push_back(to_visit)
};
}
}
}
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10 changes: 6 additions & 4 deletions tests/expected/loop-contract/multiple_loops.rs
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Expand Up @@ -11,12 +11,14 @@
fn multiple_loops() {
let mut x: u8 = kani::any_where(|i| *i >= 10);

#[kani::loop_invariant(x >= 5)]
while x > 5 {
x = x - 1;
if x != 20 {
#[kani::loop_invariant(x >= 5)]
while x > 5 {
x = x - 1;
}
}

assert!(x == 5);
assert!(x == 5 || x == 20);

#[kani::loop_invariant(x >= 2)]
while x > 2 {
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