nordic-dev.net/rust
nordic-dev.net/rust
2
0
Fork 0
mirror of https://github.com/rust-lang/rust.git synced 2025-02-05 19:43:24 +00:00
Code Issues Packages Projects Releases Wiki Activity

Remove ReversePostorder altogether

Browse Source 
It was not used anywhere, instead we directly reverse postorder.
This commit is contained in:
Maybe Waffle 2023-09-28 22:17:13 +00:00
parent f040210b31
commit 82e251be7d
1 changed files with 0 additions and 58 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

58
compiler/rustc_middle/src/mir/traversal.rs
View File

@ -226,64 +226,6 @@ pub fn postorder<'a, 'tcx>(
reverse_postorder(body).rev()
}
/// Reverse postorder traversal of a graph
///
/// Reverse postorder is the reverse order of a postorder traversal.
/// This is different to a preorder traversal and represents a natural
/// linearization of control-flow.
///
/// ```text
///
/// A
/// / \
/// / \
/// B C
/// \ /
/// \ /
/// D
/// ```
///
/// A reverse postorder traversal of this graph is either `A B C D` or `A C B D`
/// Note that for a graph containing no loops (i.e., A DAG), this is equivalent to
/// a topological sort.
///
/// Construction of a `ReversePostorder` traversal requires doing a full
/// postorder traversal of the graph, therefore this traversal should be
/// constructed as few times as possible.
#[derive(Clone)]
pub struct ReversePostorder<'a, 'tcx> {
body: &'a Body<'tcx>,
blocks: Vec<BasicBlock>,
idx: usize,
}
impl<'a, 'tcx> ReversePostorder<'a, 'tcx> {
pub fn new(body: &'a Body<'tcx>, root: BasicBlock) -> ReversePostorder<'a, 'tcx> {
let blocks: Vec<_> = Postorder::new(&body.basic_blocks, root).map(|(bb, _)| bb).collect();
let len = blocks.len();
ReversePostorder { body, blocks, idx: len }
}
}
impl<'a, 'tcx> Iterator for ReversePostorder<'a, 'tcx> {
type Item = (BasicBlock, &'a BasicBlockData<'tcx>);
fn next(&mut self) -> Option<(BasicBlock, &'a BasicBlockData<'tcx>)> {
if self.idx == 0 {
return None;
}
self.idx -= 1;
self.blocks.get(self.idx).map(|&bb| (bb, &self.body[bb]))
}
fn size_hint(&self) -> (usize, Option<usize>) {
(self.idx, Some(self.idx))
}
}
impl<'a, 'tcx> ExactSizeIterator for ReversePostorder<'a, 'tcx> {}
/// Returns an iterator over all basic blocks reachable from the `START_BLOCK` in no particular
/// order.
///