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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-30 18:31:44 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-30 18:31:44 +0000 |
commit | c23a457e72abe608715ac76f076f47dc42af07a5 (patch) | |
tree | 2772049aaf84b5c9d0ed12ec8d86812f7a7904b6 /compiler/rustc_middle/src/mir/traversal.rs | |
parent | Releasing progress-linux version 1.73.0+dfsg1-1~progress7.99u1. (diff) | |
download | rustc-c23a457e72abe608715ac76f076f47dc42af07a5.tar.xz rustc-c23a457e72abe608715ac76f076f47dc42af07a5.zip |
Merging upstream version 1.74.1+dfsg1.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'compiler/rustc_middle/src/mir/traversal.rs')
-rw-r--r-- | compiler/rustc_middle/src/mir/traversal.rs | 110 |
1 files changed, 40 insertions, 70 deletions
diff --git a/compiler/rustc_middle/src/mir/traversal.rs b/compiler/rustc_middle/src/mir/traversal.rs index ec16a8470..a1ff8410e 100644 --- a/compiler/rustc_middle/src/mir/traversal.rs +++ b/compiler/rustc_middle/src/mir/traversal.rs @@ -41,6 +41,12 @@ impl<'a, 'tcx> Preorder<'a, 'tcx> { } } +/// Preorder traversal of a graph. +/// +/// This function creates an iterator over the `Body`'s basic blocks, that +/// returns basic blocks in a preorder. +/// +/// See [`Preorder`]'s docs to learn what is preorder traversal. pub fn preorder<'a, 'tcx>(body: &'a Body<'tcx>) -> Preorder<'a, 'tcx> { Preorder::new(body, START_BLOCK) } @@ -178,7 +184,7 @@ impl<'a, 'tcx> Postorder<'a, 'tcx> { // When we yield `C` and call `traverse_successor`, we push `B` to the stack, but // since we've already visited `E`, that child isn't added to the stack. The last // two iterations yield `B` and finally `A` for a final traversal of [E, D, C, B, A] - while let Some(&mut (_, ref mut iter)) = self.visit_stack.last_mut() && let Some(bb) = iter.next_back() { + while let Some(bb) = self.visit_stack.last_mut().and_then(|(_, iter)| iter.next_back()) { if self.visited.insert(bb) { if let Some(term) = &self.basic_blocks[bb].terminator { self.visit_stack.push((bb, term.successors())); @@ -188,16 +194,14 @@ impl<'a, 'tcx> Postorder<'a, 'tcx> { } } -impl<'a, 'tcx> Iterator for Postorder<'a, 'tcx> { - type Item = (BasicBlock, &'a BasicBlockData<'tcx>); +impl<'tcx> Iterator for Postorder<'_, 'tcx> { + type Item = BasicBlock; - fn next(&mut self) -> Option<(BasicBlock, &'a BasicBlockData<'tcx>)> { - let next = self.visit_stack.pop(); - if next.is_some() { - self.traverse_successor(); - } + fn next(&mut self) -> Option<BasicBlock> { + let (bb, _) = self.visit_stack.pop()?; + self.traverse_successor(); - next.map(|(bb, _)| (bb, &self.basic_blocks[bb])) + Some(bb) } fn size_hint(&self) -> (usize, Option<usize>) { @@ -215,10 +219,14 @@ impl<'a, 'tcx> Iterator for Postorder<'a, 'tcx> { } } -/// Creates an iterator over the `Body`'s basic blocks, that: +/// Postorder traversal of a graph. +/// +/// This function creates an iterator over the `Body`'s basic blocks, that: /// - returns basic blocks in a postorder, /// - traverses the `BasicBlocks` CFG cache's reverse postorder backwards, and does not cache the /// postorder itself. +/// +/// See [`Postorder`]'s docs to learn what is postorder traversal. pub fn postorder<'a, 'tcx>( body: &'a Body<'tcx>, ) -> impl Iterator<Item = (BasicBlock, &'a BasicBlockData<'tcx>)> + ExactSizeIterator + DoubleEndedIterator @@ -226,7 +234,28 @@ pub fn postorder<'a, 'tcx>( reverse_postorder(body).rev() } -/// Reverse postorder traversal of a graph +/// Returns an iterator over all basic blocks reachable from the `START_BLOCK` in no particular +/// order. +/// +/// This is clearer than writing `preorder` in cases where the order doesn't matter. +pub fn reachable<'a, 'tcx>( + body: &'a Body<'tcx>, +) -> impl 'a + Iterator<Item = (BasicBlock, &'a BasicBlockData<'tcx>)> { + preorder(body) +} + +/// Returns a `BitSet` containing all basic blocks reachable from the `START_BLOCK`. +pub fn reachable_as_bitset(body: &Body<'_>) -> BitSet<BasicBlock> { + let mut iter = preorder(body); + iter.by_ref().for_each(drop); + iter.visited +} + +/// Reverse postorder traversal of a graph. +/// +/// This function creates an iterator over the `Body`'s basic blocks, that: +/// - returns basic blocks in a reverse postorder, +/// - makes use of the `BasicBlocks` CFG cache's reverse postorder. /// /// Reverse postorder is the reverse order of a postorder traversal. /// This is different to a preorder traversal and represents a natural @@ -246,65 +275,6 @@ pub fn postorder<'a, 'tcx>( /// 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. Use the `reset` method to be able -/// to re-use the traversal -#[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. -/// -/// This is clearer than writing `preorder` in cases where the order doesn't matter. -pub fn reachable<'a, 'tcx>( - body: &'a Body<'tcx>, -) -> impl 'a + Iterator<Item = (BasicBlock, &'a BasicBlockData<'tcx>)> { - preorder(body) -} - -/// Returns a `BitSet` containing all basic blocks reachable from the `START_BLOCK`. -pub fn reachable_as_bitset(body: &Body<'_>) -> BitSet<BasicBlock> { - let mut iter = preorder(body); - (&mut iter).for_each(drop); - iter.visited -} - -/// Creates an iterator over the `Body`'s basic blocks, that: -/// - returns basic blocks in a reverse postorder, -/// - makes use of the `BasicBlocks` CFG cache's reverse postorder. pub fn reverse_postorder<'a, 'tcx>( body: &'a Body<'tcx>, ) -> impl Iterator<Item = (BasicBlock, &'a BasicBlockData<'tcx>)> + ExactSizeIterator + DoubleEndedIterator |