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/// Ensure that the given block has return statements
/// at the end of its control flow.
///
/// Note: we don't want to blindly append a return statement
/// to the end, because it may be either redundant or invalid,
/// e.g. when the user already has returns in if/else branches.
pub fn ensure_block_returns(block: &mut crate::Block) {
use crate::Statement as S;
match block.last_mut() {
Some(&mut S::Block(ref mut b)) => {
ensure_block_returns(b);
}
Some(&mut S::If {
condition: _,
ref mut accept,
ref mut reject,
}) => {
ensure_block_returns(accept);
ensure_block_returns(reject);
}
Some(&mut S::Switch {
selector: _,
ref mut cases,
}) => {
for case in cases.iter_mut() {
if !case.fall_through {
ensure_block_returns(&mut case.body);
}
}
}
Some(&mut (S::Emit(_) | S::Break | S::Continue | S::Return { .. } | S::Kill)) => (),
Some(
&mut (S::Loop { .. }
| S::Store { .. }
| S::ImageStore { .. }
| S::Call { .. }
| S::RayQuery { .. }
| S::Atomic { .. }
| S::WorkGroupUniformLoad { .. }
| S::SubgroupBallot { .. }
| S::SubgroupCollectiveOperation { .. }
| S::SubgroupGather { .. }
| S::Barrier(_)),
)
| None => block.push(S::Return { value: None }, Default::default()),
}
}