cranelift_codegen/ir/
layout.rs

1//! Function layout.
2//!
3//! The order of basic blocks in a function and the order of instructions in a block is
4//! determined by the `Layout` data structure defined in this module.
5
6use crate::entity::SecondaryMap;
7use crate::ir::progpoint::ProgramPoint;
8use crate::ir::{Block, Inst};
9use crate::packed_option::PackedOption;
10use crate::{timing, trace};
11use core::cmp;
12
13/// The `Layout` struct determines the layout of blocks and instructions in a function. It does not
14/// contain definitions of instructions or blocks, but depends on `Inst` and `Block` entity references
15/// being defined elsewhere.
16///
17/// This data structure determines:
18///
19/// - The order of blocks in the function.
20/// - Which block contains a given instruction.
21/// - The order of instructions with a block.
22///
23/// While data dependencies are not recorded, instruction ordering does affect control
24/// dependencies, so part of the semantics of the program are determined by the layout.
25///
26#[derive(Debug, Clone, PartialEq, Hash)]
27pub struct Layout {
28    /// Linked list nodes for the layout order of blocks Forms a doubly linked list, terminated in
29    /// both ends by `None`.
30    blocks: SecondaryMap<Block, BlockNode>,
31
32    /// Linked list nodes for the layout order of instructions. Forms a double linked list per block,
33    /// terminated in both ends by `None`.
34    insts: SecondaryMap<Inst, InstNode>,
35
36    /// First block in the layout order, or `None` when no blocks have been laid out.
37    first_block: Option<Block>,
38
39    /// Last block in the layout order, or `None` when no blocks have been laid out.
40    last_block: Option<Block>,
41}
42
43impl Layout {
44    /// Create a new empty `Layout`.
45    pub fn new() -> Self {
46        Self {
47            blocks: SecondaryMap::new(),
48            insts: SecondaryMap::new(),
49            first_block: None,
50            last_block: None,
51        }
52    }
53
54    /// Clear the layout.
55    pub fn clear(&mut self) {
56        self.blocks.clear();
57        self.insts.clear();
58        self.first_block = None;
59        self.last_block = None;
60    }
61
62    /// Returns the capacity of the `BlockData` map.
63    pub fn block_capacity(&self) -> usize {
64        self.blocks.capacity()
65    }
66}
67
68/// Sequence numbers.
69///
70/// All instructions are given a sequence number that can be used to quickly determine
71/// their relative position in a block. The sequence numbers are not contiguous, but are assigned
72/// like line numbers in BASIC: 10, 20, 30, ...
73///
74/// Sequence numbers are strictly increasing within a block, but are reset between blocks.
75///
76/// The result is that sequence numbers work like BASIC line numbers for the textual form of the IR.
77type SequenceNumber = u32;
78
79/// Initial stride assigned to new sequence numbers.
80const MAJOR_STRIDE: SequenceNumber = 10;
81
82/// Secondary stride used when renumbering locally.
83const MINOR_STRIDE: SequenceNumber = 2;
84
85/// Limit on the sequence number range we'll renumber locally. If this limit is exceeded, we'll
86/// switch to a full block renumbering.
87const LOCAL_LIMIT: SequenceNumber = 100 * MINOR_STRIDE;
88
89/// Compute the midpoint between `a` and `b`.
90/// Return `None` if the midpoint would be equal to either.
91fn midpoint(a: SequenceNumber, b: SequenceNumber) -> Option<SequenceNumber> {
92    debug_assert!(a < b);
93    // Avoid integer overflow.
94    let m = a + (b - a) / 2;
95    if m > a {
96        Some(m)
97    } else {
98        None
99    }
100}
101
102#[test]
103fn test_midpoint() {
104    assert_eq!(midpoint(0, 1), None);
105    assert_eq!(midpoint(0, 2), Some(1));
106    assert_eq!(midpoint(0, 3), Some(1));
107    assert_eq!(midpoint(0, 4), Some(2));
108    assert_eq!(midpoint(1, 4), Some(2));
109    assert_eq!(midpoint(2, 4), Some(3));
110    assert_eq!(midpoint(3, 4), None);
111    assert_eq!(midpoint(3, 4), None);
112}
113
114impl Layout {
115    /// Compare the program points `a` and `b` in the same block relative to this program order.
116    ///
117    /// Return `Less` if `a` appears in the program before `b`.
118    ///
119    /// This is declared as a generic such that it can be called with `Inst` and `Block` arguments
120    /// directly. Depending on the implementation, there is a good chance performance will be
121    /// improved for those cases where the type of either argument is known statically.
122    pub fn pp_cmp<A, B>(&self, a: A, b: B) -> cmp::Ordering
123    where
124        A: Into<ProgramPoint>,
125        B: Into<ProgramPoint>,
126    {
127        let a = a.into();
128        let b = b.into();
129        debug_assert_eq!(self.pp_block(a), self.pp_block(b));
130        let a_seq = match a {
131            ProgramPoint::Block(_block) => 0,
132            ProgramPoint::Inst(inst) => self.insts[inst].seq,
133        };
134        let b_seq = match b {
135            ProgramPoint::Block(_block) => 0,
136            ProgramPoint::Inst(inst) => self.insts[inst].seq,
137        };
138        a_seq.cmp(&b_seq)
139    }
140}
141
142// Private methods for dealing with sequence numbers.
143impl Layout {
144    /// Assign a valid sequence number to `inst` such that the numbers are still monotonic. This may
145    /// require renumbering.
146    fn assign_inst_seq(&mut self, inst: Inst) {
147        // Get the sequence number immediately before `inst`.
148        let prev_seq = match self.insts[inst].prev.expand() {
149            Some(prev_inst) => self.insts[prev_inst].seq,
150            None => 0,
151        };
152
153        // Get the sequence number immediately following `inst`.
154        let next_seq = if let Some(next_inst) = self.insts[inst].next.expand() {
155            self.insts[next_inst].seq
156        } else {
157            // There is nothing after `inst`. We can just use a major stride.
158            self.insts[inst].seq = prev_seq + MAJOR_STRIDE;
159            return;
160        };
161
162        // Check if there is room between these sequence numbers.
163        if let Some(seq) = midpoint(prev_seq, next_seq) {
164            self.insts[inst].seq = seq;
165        } else {
166            // No available integers between `prev_seq` and `next_seq`. We have to renumber.
167            self.renumber_insts(inst, prev_seq + MINOR_STRIDE, prev_seq + LOCAL_LIMIT);
168        }
169    }
170
171    /// Renumber instructions starting from `inst` until the end of the block or until numbers catch
172    /// up.
173    ///
174    /// If sequence numbers exceed `limit`, switch to a full block renumbering.
175    fn renumber_insts(&mut self, inst: Inst, seq: SequenceNumber, limit: SequenceNumber) {
176        let mut inst = inst;
177        let mut seq = seq;
178
179        loop {
180            self.insts[inst].seq = seq;
181
182            // Next instruction.
183            inst = match self.insts[inst].next.expand() {
184                None => return,
185                Some(next) => next,
186            };
187
188            if seq < self.insts[inst].seq {
189                // Sequence caught up.
190                return;
191            }
192
193            if seq > limit {
194                // We're pushing too many instructions in front of us.
195                // Switch to a full block renumbering to make some space.
196                self.full_block_renumber(
197                    self.inst_block(inst)
198                        .expect("inst must be inserted before assigning an seq"),
199                );
200                return;
201            }
202
203            seq += MINOR_STRIDE;
204        }
205    }
206
207    /// Renumber all instructions in a block.
208    ///
209    /// This doesn't affect the position of anything, but it gives more room in the internal
210    /// sequence numbers for inserting instructions later.
211    fn full_block_renumber(&mut self, block: Block) {
212        let _tt = timing::layout_renumber();
213        // Avoid 0 as this is reserved for the program point indicating the block itself
214        let mut seq = MAJOR_STRIDE;
215        let mut next_inst = self.blocks[block].first_inst.expand();
216        while let Some(inst) = next_inst {
217            self.insts[inst].seq = seq;
218            seq += MAJOR_STRIDE;
219            next_inst = self.insts[inst].next.expand();
220        }
221
222        trace!("Renumbered {} program points", seq / MAJOR_STRIDE);
223    }
224}
225
226/// Methods for laying out blocks.
227///
228/// An unknown block starts out as *not inserted* in the block layout. The layout is a linear order of
229/// inserted blocks. Once a block has been inserted in the layout, instructions can be added. A block
230/// can only be removed from the layout when it is empty.
231///
232/// Since every block must end with a terminator instruction which cannot fall through, the layout of
233/// blocks do not affect the semantics of the program.
234///
235impl Layout {
236    /// Is `block` currently part of the layout?
237    pub fn is_block_inserted(&self, block: Block) -> bool {
238        Some(block) == self.first_block || self.blocks[block].prev.is_some()
239    }
240
241    /// Insert `block` as the last block in the layout.
242    pub fn append_block(&mut self, block: Block) {
243        debug_assert!(
244            !self.is_block_inserted(block),
245            "Cannot append block that is already in the layout"
246        );
247        {
248            let node = &mut self.blocks[block];
249            debug_assert!(node.first_inst.is_none() && node.last_inst.is_none());
250            node.prev = self.last_block.into();
251            node.next = None.into();
252        }
253        if let Some(last) = self.last_block {
254            self.blocks[last].next = block.into();
255        } else {
256            self.first_block = Some(block);
257        }
258        self.last_block = Some(block);
259    }
260
261    /// Insert `block` in the layout before the existing block `before`.
262    pub fn insert_block(&mut self, block: Block, before: Block) {
263        debug_assert!(
264            !self.is_block_inserted(block),
265            "Cannot insert block that is already in the layout"
266        );
267        debug_assert!(
268            self.is_block_inserted(before),
269            "block Insertion point not in the layout"
270        );
271        let after = self.blocks[before].prev;
272        {
273            let node = &mut self.blocks[block];
274            node.next = before.into();
275            node.prev = after;
276        }
277        self.blocks[before].prev = block.into();
278        match after.expand() {
279            None => self.first_block = Some(block),
280            Some(a) => self.blocks[a].next = block.into(),
281        }
282    }
283
284    /// Insert `block` in the layout *after* the existing block `after`.
285    pub fn insert_block_after(&mut self, block: Block, after: Block) {
286        debug_assert!(
287            !self.is_block_inserted(block),
288            "Cannot insert block that is already in the layout"
289        );
290        debug_assert!(
291            self.is_block_inserted(after),
292            "block Insertion point not in the layout"
293        );
294        let before = self.blocks[after].next;
295        {
296            let node = &mut self.blocks[block];
297            node.next = before;
298            node.prev = after.into();
299        }
300        self.blocks[after].next = block.into();
301        match before.expand() {
302            None => self.last_block = Some(block),
303            Some(b) => self.blocks[b].prev = block.into(),
304        }
305    }
306
307    /// Remove `block` from the layout.
308    pub fn remove_block(&mut self, block: Block) {
309        debug_assert!(self.is_block_inserted(block), "block not in the layout");
310        debug_assert!(self.first_inst(block).is_none(), "block must be empty.");
311
312        // Clear the `block` node and extract links.
313        let prev;
314        let next;
315        {
316            let n = &mut self.blocks[block];
317            prev = n.prev;
318            next = n.next;
319            n.prev = None.into();
320            n.next = None.into();
321        }
322        // Fix up links to `block`.
323        match prev.expand() {
324            None => self.first_block = next.expand(),
325            Some(p) => self.blocks[p].next = next,
326        }
327        match next.expand() {
328            None => self.last_block = prev.expand(),
329            Some(n) => self.blocks[n].prev = prev,
330        }
331    }
332
333    /// Return an iterator over all blocks in layout order.
334    pub fn blocks(&self) -> Blocks {
335        Blocks {
336            layout: self,
337            next: self.first_block,
338        }
339    }
340
341    /// Get the function's entry block.
342    /// This is simply the first block in the layout order.
343    pub fn entry_block(&self) -> Option<Block> {
344        self.first_block
345    }
346
347    /// Get the last block in the layout.
348    pub fn last_block(&self) -> Option<Block> {
349        self.last_block
350    }
351
352    /// Get the block preceding `block` in the layout order.
353    pub fn prev_block(&self, block: Block) -> Option<Block> {
354        self.blocks[block].prev.expand()
355    }
356
357    /// Get the block following `block` in the layout order.
358    pub fn next_block(&self, block: Block) -> Option<Block> {
359        self.blocks[block].next.expand()
360    }
361
362    /// Mark a block as "cold".
363    ///
364    /// This will try to move it out of the ordinary path of execution
365    /// when lowered to machine code.
366    pub fn set_cold(&mut self, block: Block) {
367        self.blocks[block].cold = true;
368    }
369
370    /// Is the given block cold?
371    pub fn is_cold(&self, block: Block) -> bool {
372        self.blocks[block].cold
373    }
374}
375
376/// A single node in the linked-list of blocks.
377// **Note:** Whenever you add new fields here, don't forget to update the custom serializer for `Layout` too.
378#[derive(Clone, Debug, Default, PartialEq, Hash)]
379struct BlockNode {
380    prev: PackedOption<Block>,
381    next: PackedOption<Block>,
382    first_inst: PackedOption<Inst>,
383    last_inst: PackedOption<Inst>,
384    cold: bool,
385}
386
387/// Iterate over blocks in layout order. See [crate::ir::layout::Layout::blocks].
388pub struct Blocks<'f> {
389    layout: &'f Layout,
390    next: Option<Block>,
391}
392
393impl<'f> Iterator for Blocks<'f> {
394    type Item = Block;
395
396    fn next(&mut self) -> Option<Block> {
397        match self.next {
398            Some(block) => {
399                self.next = self.layout.next_block(block);
400                Some(block)
401            }
402            None => None,
403        }
404    }
405}
406
407/// Use a layout reference in a for loop.
408impl<'f> IntoIterator for &'f Layout {
409    type Item = Block;
410    type IntoIter = Blocks<'f>;
411
412    fn into_iter(self) -> Blocks<'f> {
413        self.blocks()
414    }
415}
416
417/// Methods for arranging instructions.
418///
419/// An instruction starts out as *not inserted* in the layout. An instruction can be inserted into
420/// a block at a given position.
421impl Layout {
422    /// Get the block containing `inst`, or `None` if `inst` is not inserted in the layout.
423    pub fn inst_block(&self, inst: Inst) -> Option<Block> {
424        self.insts[inst].block.into()
425    }
426
427    /// Get the block containing the program point `pp`. Panic if `pp` is not in the layout.
428    pub fn pp_block(&self, pp: ProgramPoint) -> Block {
429        match pp {
430            ProgramPoint::Block(block) => block,
431            ProgramPoint::Inst(inst) => self.inst_block(inst).expect("Program point not in layout"),
432        }
433    }
434
435    /// Append `inst` to the end of `block`.
436    pub fn append_inst(&mut self, inst: Inst, block: Block) {
437        debug_assert_eq!(self.inst_block(inst), None);
438        debug_assert!(
439            self.is_block_inserted(block),
440            "Cannot append instructions to block not in layout"
441        );
442        {
443            let block_node = &mut self.blocks[block];
444            {
445                let inst_node = &mut self.insts[inst];
446                inst_node.block = block.into();
447                inst_node.prev = block_node.last_inst;
448                debug_assert!(inst_node.next.is_none());
449            }
450            if block_node.first_inst.is_none() {
451                block_node.first_inst = inst.into();
452            } else {
453                self.insts[block_node.last_inst.unwrap()].next = inst.into();
454            }
455            block_node.last_inst = inst.into();
456        }
457        self.assign_inst_seq(inst);
458    }
459
460    /// Fetch a block's first instruction.
461    pub fn first_inst(&self, block: Block) -> Option<Inst> {
462        self.blocks[block].first_inst.into()
463    }
464
465    /// Fetch a block's last instruction.
466    pub fn last_inst(&self, block: Block) -> Option<Inst> {
467        self.blocks[block].last_inst.into()
468    }
469
470    /// Fetch the instruction following `inst`.
471    pub fn next_inst(&self, inst: Inst) -> Option<Inst> {
472        self.insts[inst].next.expand()
473    }
474
475    /// Fetch the instruction preceding `inst`.
476    pub fn prev_inst(&self, inst: Inst) -> Option<Inst> {
477        self.insts[inst].prev.expand()
478    }
479
480    /// Insert `inst` before the instruction `before` in the same block.
481    pub fn insert_inst(&mut self, inst: Inst, before: Inst) {
482        debug_assert_eq!(self.inst_block(inst), None);
483        let block = self
484            .inst_block(before)
485            .expect("Instruction before insertion point not in the layout");
486        let after = self.insts[before].prev;
487        {
488            let inst_node = &mut self.insts[inst];
489            inst_node.block = block.into();
490            inst_node.next = before.into();
491            inst_node.prev = after;
492        }
493        self.insts[before].prev = inst.into();
494        match after.expand() {
495            None => self.blocks[block].first_inst = inst.into(),
496            Some(a) => self.insts[a].next = inst.into(),
497        }
498        self.assign_inst_seq(inst);
499    }
500
501    /// Remove `inst` from the layout.
502    pub fn remove_inst(&mut self, inst: Inst) {
503        let block = self.inst_block(inst).expect("Instruction already removed.");
504        // Clear the `inst` node and extract links.
505        let prev;
506        let next;
507        {
508            let n = &mut self.insts[inst];
509            prev = n.prev;
510            next = n.next;
511            n.block = None.into();
512            n.prev = None.into();
513            n.next = None.into();
514        }
515        // Fix up links to `inst`.
516        match prev.expand() {
517            None => self.blocks[block].first_inst = next,
518            Some(p) => self.insts[p].next = next,
519        }
520        match next.expand() {
521            None => self.blocks[block].last_inst = prev,
522            Some(n) => self.insts[n].prev = prev,
523        }
524    }
525
526    /// Iterate over the instructions in `block` in layout order.
527    pub fn block_insts(&self, block: Block) -> Insts {
528        Insts {
529            layout: self,
530            head: self.blocks[block].first_inst.into(),
531            tail: self.blocks[block].last_inst.into(),
532        }
533    }
534
535    /// Split the block containing `before` in two.
536    ///
537    /// Insert `new_block` after the old block and move `before` and the following instructions to
538    /// `new_block`:
539    ///
540    /// ```text
541    /// old_block:
542    ///     i1
543    ///     i2
544    ///     i3 << before
545    ///     i4
546    /// ```
547    /// becomes:
548    ///
549    /// ```text
550    /// old_block:
551    ///     i1
552    ///     i2
553    /// new_block:
554    ///     i3 << before
555    ///     i4
556    /// ```
557    pub fn split_block(&mut self, new_block: Block, before: Inst) {
558        let old_block = self
559            .inst_block(before)
560            .expect("The `before` instruction must be in the layout");
561        debug_assert!(!self.is_block_inserted(new_block));
562
563        // Insert new_block after old_block.
564        let next_block = self.blocks[old_block].next;
565        let last_inst = self.blocks[old_block].last_inst;
566        {
567            let node = &mut self.blocks[new_block];
568            node.prev = old_block.into();
569            node.next = next_block;
570            node.first_inst = before.into();
571            node.last_inst = last_inst;
572        }
573        self.blocks[old_block].next = new_block.into();
574
575        // Fix backwards link.
576        if Some(old_block) == self.last_block {
577            self.last_block = Some(new_block);
578        } else {
579            self.blocks[next_block.unwrap()].prev = new_block.into();
580        }
581
582        // Disconnect the instruction links.
583        let prev_inst = self.insts[before].prev;
584        self.insts[before].prev = None.into();
585        self.blocks[old_block].last_inst = prev_inst;
586        match prev_inst.expand() {
587            None => self.blocks[old_block].first_inst = None.into(),
588            Some(pi) => self.insts[pi].next = None.into(),
589        }
590
591        // Fix the instruction -> block pointers.
592        let mut opt_i = Some(before);
593        while let Some(i) = opt_i {
594            debug_assert_eq!(self.insts[i].block.expand(), Some(old_block));
595            self.insts[i].block = new_block.into();
596            opt_i = self.insts[i].next.into();
597        }
598    }
599}
600
601#[derive(Clone, Debug, Default)]
602struct InstNode {
603    /// The Block containing this instruction, or `None` if the instruction is not yet inserted.
604    block: PackedOption<Block>,
605    prev: PackedOption<Inst>,
606    next: PackedOption<Inst>,
607    seq: SequenceNumber,
608}
609
610impl PartialEq for InstNode {
611    fn eq(&self, other: &Self) -> bool {
612        // Ignore the sequence number as it is an optimization used by pp_cmp and may be different
613        // even for equivalent layouts.
614        self.block == other.block && self.prev == other.prev && self.next == other.next
615    }
616}
617
618impl core::hash::Hash for InstNode {
619    fn hash<H: core::hash::Hasher>(&self, state: &mut H) {
620        // Ignore the sequence number as it is an optimization used by pp_cmp and may be different
621        // even for equivalent layouts.
622        self.block.hash(state);
623        self.prev.hash(state);
624        self.next.hash(state);
625    }
626}
627
628/// Iterate over instructions in a block in layout order. See `Layout::block_insts()`.
629pub struct Insts<'f> {
630    layout: &'f Layout,
631    head: Option<Inst>,
632    tail: Option<Inst>,
633}
634
635impl<'f> Iterator for Insts<'f> {
636    type Item = Inst;
637
638    fn next(&mut self) -> Option<Inst> {
639        let rval = self.head;
640        if let Some(inst) = rval {
641            if self.head == self.tail {
642                self.head = None;
643                self.tail = None;
644            } else {
645                self.head = self.layout.insts[inst].next.into();
646            }
647        }
648        rval
649    }
650}
651
652impl<'f> DoubleEndedIterator for Insts<'f> {
653    fn next_back(&mut self) -> Option<Inst> {
654        let rval = self.tail;
655        if let Some(inst) = rval {
656            if self.head == self.tail {
657                self.head = None;
658                self.tail = None;
659            } else {
660                self.tail = self.layout.insts[inst].prev.into();
661            }
662        }
663        rval
664    }
665}
666
667/// A custom serialize and deserialize implementation for [`Layout`].
668///
669/// This doesn't use a derived implementation as [`Layout`] is a manual implementation of a linked
670/// list. Storing it directly as a regular list saves a lot of space.
671///
672/// The following format is used. (notated in EBNF form)
673///
674/// ```plain
675/// data = block_data * ;
676/// block_data = "block_id" , "cold" , "inst_count" , ( "inst_id" * ) ;
677/// ```
678#[cfg(feature = "enable-serde")]
679mod serde {
680    use ::serde::de::{Deserializer, Error, SeqAccess, Visitor};
681    use ::serde::ser::{SerializeSeq, Serializer};
682    use ::serde::{Deserialize, Serialize};
683    use core::fmt;
684    use core::marker::PhantomData;
685
686    use super::*;
687
688    impl Serialize for Layout {
689        fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
690        where
691            S: Serializer,
692        {
693            let size = self.blocks().count() * 3
694                + self
695                    .blocks()
696                    .map(|block| self.block_insts(block).count())
697                    .sum::<usize>();
698            let mut seq = serializer.serialize_seq(Some(size))?;
699            for block in self.blocks() {
700                seq.serialize_element(&block)?;
701                seq.serialize_element(&self.blocks[block].cold)?;
702                seq.serialize_element(&u32::try_from(self.block_insts(block).count()).unwrap())?;
703                for inst in self.block_insts(block) {
704                    seq.serialize_element(&inst)?;
705                }
706            }
707            seq.end()
708        }
709    }
710
711    impl<'de> Deserialize<'de> for Layout {
712        fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
713        where
714            D: Deserializer<'de>,
715        {
716            deserializer.deserialize_seq(LayoutVisitor {
717                marker: PhantomData,
718            })
719        }
720    }
721
722    struct LayoutVisitor {
723        marker: PhantomData<fn() -> Layout>,
724    }
725
726    impl<'de> Visitor<'de> for LayoutVisitor {
727        type Value = Layout;
728
729        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
730            write!(formatter, "a `cranelift_codegen::ir::Layout`")
731        }
732
733        fn visit_seq<M>(self, mut access: M) -> Result<Self::Value, M::Error>
734        where
735            M: SeqAccess<'de>,
736        {
737            let mut layout = Layout::new();
738
739            while let Some(block) = access.next_element::<Block>()? {
740                layout.append_block(block);
741
742                let cold = access
743                    .next_element::<bool>()?
744                    .ok_or_else(|| Error::missing_field("cold"))?;
745                layout.blocks[block].cold = cold;
746
747                let count = access
748                    .next_element::<u32>()?
749                    .ok_or_else(|| Error::missing_field("count"))?;
750
751                for _ in 0..count {
752                    let inst = access
753                        .next_element::<Inst>()?
754                        .ok_or_else(|| Error::missing_field("inst"))?;
755                    layout.append_inst(inst, block);
756                }
757            }
758
759            Ok(layout)
760        }
761    }
762}
763
764#[cfg(test)]
765mod tests {
766    use super::Layout;
767    use crate::cursor::{Cursor, CursorPosition};
768    use crate::entity::EntityRef;
769    use crate::ir::{Block, Inst, SourceLoc};
770    use alloc::vec::Vec;
771    use core::cmp::Ordering;
772
773    struct LayoutCursor<'f> {
774        /// Borrowed function layout. Public so it can be re-borrowed from this cursor.
775        pub layout: &'f mut Layout,
776        pos: CursorPosition,
777    }
778
779    impl<'f> Cursor for LayoutCursor<'f> {
780        fn position(&self) -> CursorPosition {
781            self.pos
782        }
783
784        fn set_position(&mut self, pos: CursorPosition) {
785            self.pos = pos;
786        }
787
788        fn srcloc(&self) -> SourceLoc {
789            unimplemented!()
790        }
791
792        fn set_srcloc(&mut self, _srcloc: SourceLoc) {
793            unimplemented!()
794        }
795
796        fn layout(&self) -> &Layout {
797            self.layout
798        }
799
800        fn layout_mut(&mut self) -> &mut Layout {
801            self.layout
802        }
803    }
804
805    impl<'f> LayoutCursor<'f> {
806        /// Create a new `LayoutCursor` for `layout`.
807        /// The cursor holds a mutable reference to `layout` for its entire lifetime.
808        pub fn new(layout: &'f mut Layout) -> Self {
809            Self {
810                layout,
811                pos: CursorPosition::Nowhere,
812            }
813        }
814    }
815
816    fn verify(layout: &mut Layout, blocks: &[(Block, &[Inst])]) {
817        // Check that blocks are inserted and instructions belong the right places.
818        // Check forward linkage with iterators.
819        // Check that layout sequence numbers are strictly monotonic.
820        {
821            let mut block_iter = layout.blocks();
822            for &(block, insts) in blocks {
823                assert!(layout.is_block_inserted(block));
824                assert_eq!(block_iter.next(), Some(block));
825
826                let mut seq = 0;
827                let mut inst_iter = layout.block_insts(block);
828                for &inst in insts {
829                    assert_eq!(layout.inst_block(inst), Some(block));
830                    assert_eq!(inst_iter.next(), Some(inst));
831                    assert!(layout.insts[inst].seq > seq);
832                    seq = layout.insts[inst].seq;
833                }
834                assert_eq!(inst_iter.next(), None);
835            }
836            assert_eq!(block_iter.next(), None);
837        }
838
839        // Check backwards linkage with a cursor.
840        let mut cur = LayoutCursor::new(layout);
841        for &(block, insts) in blocks.into_iter().rev() {
842            assert_eq!(cur.prev_block(), Some(block));
843            for &inst in insts.into_iter().rev() {
844                assert_eq!(cur.prev_inst(), Some(inst));
845            }
846            assert_eq!(cur.prev_inst(), None);
847        }
848        assert_eq!(cur.prev_block(), None);
849    }
850
851    #[test]
852    fn append_block() {
853        let mut layout = Layout::new();
854        let e0 = Block::new(0);
855        let e1 = Block::new(1);
856        let e2 = Block::new(2);
857
858        {
859            let imm = &layout;
860            assert!(!imm.is_block_inserted(e0));
861            assert!(!imm.is_block_inserted(e1));
862        }
863        verify(&mut layout, &[]);
864
865        layout.append_block(e1);
866        assert!(!layout.is_block_inserted(e0));
867        assert!(layout.is_block_inserted(e1));
868        assert!(!layout.is_block_inserted(e2));
869        let v: Vec<Block> = layout.blocks().collect();
870        assert_eq!(v, [e1]);
871
872        layout.append_block(e2);
873        assert!(!layout.is_block_inserted(e0));
874        assert!(layout.is_block_inserted(e1));
875        assert!(layout.is_block_inserted(e2));
876        let v: Vec<Block> = layout.blocks().collect();
877        assert_eq!(v, [e1, e2]);
878
879        layout.append_block(e0);
880        assert!(layout.is_block_inserted(e0));
881        assert!(layout.is_block_inserted(e1));
882        assert!(layout.is_block_inserted(e2));
883        let v: Vec<Block> = layout.blocks().collect();
884        assert_eq!(v, [e1, e2, e0]);
885
886        {
887            let imm = &layout;
888            let mut v = Vec::new();
889            for e in imm {
890                v.push(e);
891            }
892            assert_eq!(v, [e1, e2, e0]);
893        }
894
895        // Test cursor positioning.
896        let mut cur = LayoutCursor::new(&mut layout);
897        assert_eq!(cur.position(), CursorPosition::Nowhere);
898        assert_eq!(cur.next_inst(), None);
899        assert_eq!(cur.position(), CursorPosition::Nowhere);
900        assert_eq!(cur.prev_inst(), None);
901        assert_eq!(cur.position(), CursorPosition::Nowhere);
902
903        assert_eq!(cur.next_block(), Some(e1));
904        assert_eq!(cur.position(), CursorPosition::Before(e1));
905        assert_eq!(cur.next_inst(), None);
906        assert_eq!(cur.position(), CursorPosition::After(e1));
907        assert_eq!(cur.next_inst(), None);
908        assert_eq!(cur.position(), CursorPosition::After(e1));
909        assert_eq!(cur.next_block(), Some(e2));
910        assert_eq!(cur.prev_inst(), None);
911        assert_eq!(cur.position(), CursorPosition::Before(e2));
912        assert_eq!(cur.next_block(), Some(e0));
913        assert_eq!(cur.next_block(), None);
914        assert_eq!(cur.position(), CursorPosition::Nowhere);
915
916        // Backwards through the blocks.
917        assert_eq!(cur.prev_block(), Some(e0));
918        assert_eq!(cur.position(), CursorPosition::After(e0));
919        assert_eq!(cur.prev_block(), Some(e2));
920        assert_eq!(cur.prev_block(), Some(e1));
921        assert_eq!(cur.prev_block(), None);
922        assert_eq!(cur.position(), CursorPosition::Nowhere);
923    }
924
925    #[test]
926    fn insert_block() {
927        let mut layout = Layout::new();
928        let e0 = Block::new(0);
929        let e1 = Block::new(1);
930        let e2 = Block::new(2);
931
932        {
933            let imm = &layout;
934            assert!(!imm.is_block_inserted(e0));
935            assert!(!imm.is_block_inserted(e1));
936
937            let v: Vec<Block> = layout.blocks().collect();
938            assert_eq!(v, []);
939        }
940
941        layout.append_block(e1);
942        assert!(!layout.is_block_inserted(e0));
943        assert!(layout.is_block_inserted(e1));
944        assert!(!layout.is_block_inserted(e2));
945        verify(&mut layout, &[(e1, &[])]);
946
947        layout.insert_block(e2, e1);
948        assert!(!layout.is_block_inserted(e0));
949        assert!(layout.is_block_inserted(e1));
950        assert!(layout.is_block_inserted(e2));
951        verify(&mut layout, &[(e2, &[]), (e1, &[])]);
952
953        layout.insert_block(e0, e1);
954        assert!(layout.is_block_inserted(e0));
955        assert!(layout.is_block_inserted(e1));
956        assert!(layout.is_block_inserted(e2));
957        verify(&mut layout, &[(e2, &[]), (e0, &[]), (e1, &[])]);
958    }
959
960    #[test]
961    fn insert_block_after() {
962        let mut layout = Layout::new();
963        let e0 = Block::new(0);
964        let e1 = Block::new(1);
965        let e2 = Block::new(2);
966
967        layout.append_block(e1);
968        layout.insert_block_after(e2, e1);
969        verify(&mut layout, &[(e1, &[]), (e2, &[])]);
970
971        layout.insert_block_after(e0, e1);
972        verify(&mut layout, &[(e1, &[]), (e0, &[]), (e2, &[])]);
973    }
974
975    #[test]
976    fn append_inst() {
977        let mut layout = Layout::new();
978        let e1 = Block::new(1);
979
980        layout.append_block(e1);
981        let v: Vec<Inst> = layout.block_insts(e1).collect();
982        assert_eq!(v, []);
983
984        let i0 = Inst::new(0);
985        let i1 = Inst::new(1);
986        let i2 = Inst::new(2);
987
988        assert_eq!(layout.inst_block(i0), None);
989        assert_eq!(layout.inst_block(i1), None);
990        assert_eq!(layout.inst_block(i2), None);
991
992        layout.append_inst(i1, e1);
993        assert_eq!(layout.inst_block(i0), None);
994        assert_eq!(layout.inst_block(i1), Some(e1));
995        assert_eq!(layout.inst_block(i2), None);
996        let v: Vec<Inst> = layout.block_insts(e1).collect();
997        assert_eq!(v, [i1]);
998
999        layout.append_inst(i2, e1);
1000        assert_eq!(layout.inst_block(i0), None);
1001        assert_eq!(layout.inst_block(i1), Some(e1));
1002        assert_eq!(layout.inst_block(i2), Some(e1));
1003        let v: Vec<Inst> = layout.block_insts(e1).collect();
1004        assert_eq!(v, [i1, i2]);
1005
1006        // Test double-ended instruction iterator.
1007        let v: Vec<Inst> = layout.block_insts(e1).rev().collect();
1008        assert_eq!(v, [i2, i1]);
1009
1010        layout.append_inst(i0, e1);
1011        verify(&mut layout, &[(e1, &[i1, i2, i0])]);
1012
1013        // Test cursor positioning.
1014        let mut cur = LayoutCursor::new(&mut layout).at_top(e1);
1015        assert_eq!(cur.position(), CursorPosition::Before(e1));
1016        assert_eq!(cur.prev_inst(), None);
1017        assert_eq!(cur.position(), CursorPosition::Before(e1));
1018        assert_eq!(cur.next_inst(), Some(i1));
1019        assert_eq!(cur.position(), CursorPosition::At(i1));
1020        assert_eq!(cur.next_inst(), Some(i2));
1021        assert_eq!(cur.next_inst(), Some(i0));
1022        assert_eq!(cur.prev_inst(), Some(i2));
1023        assert_eq!(cur.position(), CursorPosition::At(i2));
1024        assert_eq!(cur.next_inst(), Some(i0));
1025        assert_eq!(cur.position(), CursorPosition::At(i0));
1026        assert_eq!(cur.next_inst(), None);
1027        assert_eq!(cur.position(), CursorPosition::After(e1));
1028        assert_eq!(cur.next_inst(), None);
1029        assert_eq!(cur.position(), CursorPosition::After(e1));
1030        assert_eq!(cur.prev_inst(), Some(i0));
1031        assert_eq!(cur.prev_inst(), Some(i2));
1032        assert_eq!(cur.prev_inst(), Some(i1));
1033        assert_eq!(cur.prev_inst(), None);
1034        assert_eq!(cur.position(), CursorPosition::Before(e1));
1035
1036        // Test remove_inst.
1037        cur.goto_inst(i2);
1038        assert_eq!(cur.remove_inst(), i2);
1039        verify(cur.layout, &[(e1, &[i1, i0])]);
1040        assert_eq!(cur.layout.inst_block(i2), None);
1041        assert_eq!(cur.remove_inst(), i0);
1042        verify(cur.layout, &[(e1, &[i1])]);
1043        assert_eq!(cur.layout.inst_block(i0), None);
1044        assert_eq!(cur.position(), CursorPosition::After(e1));
1045        cur.layout.remove_inst(i1);
1046        verify(cur.layout, &[(e1, &[])]);
1047        assert_eq!(cur.layout.inst_block(i1), None);
1048    }
1049
1050    #[test]
1051    fn insert_inst() {
1052        let mut layout = Layout::new();
1053        let e1 = Block::new(1);
1054
1055        layout.append_block(e1);
1056        let v: Vec<Inst> = layout.block_insts(e1).collect();
1057        assert_eq!(v, []);
1058
1059        let i0 = Inst::new(0);
1060        let i1 = Inst::new(1);
1061        let i2 = Inst::new(2);
1062
1063        assert_eq!(layout.inst_block(i0), None);
1064        assert_eq!(layout.inst_block(i1), None);
1065        assert_eq!(layout.inst_block(i2), None);
1066
1067        layout.append_inst(i1, e1);
1068        assert_eq!(layout.inst_block(i0), None);
1069        assert_eq!(layout.inst_block(i1), Some(e1));
1070        assert_eq!(layout.inst_block(i2), None);
1071        let v: Vec<Inst> = layout.block_insts(e1).collect();
1072        assert_eq!(v, [i1]);
1073
1074        layout.insert_inst(i2, i1);
1075        assert_eq!(layout.inst_block(i0), None);
1076        assert_eq!(layout.inst_block(i1), Some(e1));
1077        assert_eq!(layout.inst_block(i2), Some(e1));
1078        let v: Vec<Inst> = layout.block_insts(e1).collect();
1079        assert_eq!(v, [i2, i1]);
1080
1081        layout.insert_inst(i0, i1);
1082        verify(&mut layout, &[(e1, &[i2, i0, i1])]);
1083    }
1084
1085    #[test]
1086    fn multiple_blocks() {
1087        let mut layout = Layout::new();
1088
1089        let e0 = Block::new(0);
1090        let e1 = Block::new(1);
1091
1092        assert_eq!(layout.entry_block(), None);
1093        layout.append_block(e0);
1094        assert_eq!(layout.entry_block(), Some(e0));
1095        layout.append_block(e1);
1096        assert_eq!(layout.entry_block(), Some(e0));
1097
1098        let i0 = Inst::new(0);
1099        let i1 = Inst::new(1);
1100        let i2 = Inst::new(2);
1101        let i3 = Inst::new(3);
1102
1103        layout.append_inst(i0, e0);
1104        layout.append_inst(i1, e0);
1105        layout.append_inst(i2, e1);
1106        layout.append_inst(i3, e1);
1107
1108        let v0: Vec<Inst> = layout.block_insts(e0).collect();
1109        let v1: Vec<Inst> = layout.block_insts(e1).collect();
1110        assert_eq!(v0, [i0, i1]);
1111        assert_eq!(v1, [i2, i3]);
1112    }
1113
1114    #[test]
1115    fn split_block() {
1116        let mut layout = Layout::new();
1117
1118        let e0 = Block::new(0);
1119        let e1 = Block::new(1);
1120        let e2 = Block::new(2);
1121
1122        let i0 = Inst::new(0);
1123        let i1 = Inst::new(1);
1124        let i2 = Inst::new(2);
1125        let i3 = Inst::new(3);
1126
1127        layout.append_block(e0);
1128        layout.append_inst(i0, e0);
1129        assert_eq!(layout.inst_block(i0), Some(e0));
1130        layout.split_block(e1, i0);
1131        assert_eq!(layout.inst_block(i0), Some(e1));
1132
1133        {
1134            let mut cur = LayoutCursor::new(&mut layout);
1135            assert_eq!(cur.next_block(), Some(e0));
1136            assert_eq!(cur.next_inst(), None);
1137            assert_eq!(cur.next_block(), Some(e1));
1138            assert_eq!(cur.next_inst(), Some(i0));
1139            assert_eq!(cur.next_inst(), None);
1140            assert_eq!(cur.next_block(), None);
1141
1142            // Check backwards links.
1143            assert_eq!(cur.prev_block(), Some(e1));
1144            assert_eq!(cur.prev_inst(), Some(i0));
1145            assert_eq!(cur.prev_inst(), None);
1146            assert_eq!(cur.prev_block(), Some(e0));
1147            assert_eq!(cur.prev_inst(), None);
1148            assert_eq!(cur.prev_block(), None);
1149        }
1150
1151        layout.append_inst(i1, e0);
1152        layout.append_inst(i2, e0);
1153        layout.append_inst(i3, e0);
1154        layout.split_block(e2, i2);
1155
1156        assert_eq!(layout.inst_block(i0), Some(e1));
1157        assert_eq!(layout.inst_block(i1), Some(e0));
1158        assert_eq!(layout.inst_block(i2), Some(e2));
1159        assert_eq!(layout.inst_block(i3), Some(e2));
1160
1161        {
1162            let mut cur = LayoutCursor::new(&mut layout);
1163            assert_eq!(cur.next_block(), Some(e0));
1164            assert_eq!(cur.next_inst(), Some(i1));
1165            assert_eq!(cur.next_inst(), None);
1166            assert_eq!(cur.next_block(), Some(e2));
1167            assert_eq!(cur.next_inst(), Some(i2));
1168            assert_eq!(cur.next_inst(), Some(i3));
1169            assert_eq!(cur.next_inst(), None);
1170            assert_eq!(cur.next_block(), Some(e1));
1171            assert_eq!(cur.next_inst(), Some(i0));
1172            assert_eq!(cur.next_inst(), None);
1173            assert_eq!(cur.next_block(), None);
1174
1175            assert_eq!(cur.prev_block(), Some(e1));
1176            assert_eq!(cur.prev_inst(), Some(i0));
1177            assert_eq!(cur.prev_inst(), None);
1178            assert_eq!(cur.prev_block(), Some(e2));
1179            assert_eq!(cur.prev_inst(), Some(i3));
1180            assert_eq!(cur.prev_inst(), Some(i2));
1181            assert_eq!(cur.prev_inst(), None);
1182            assert_eq!(cur.prev_block(), Some(e0));
1183            assert_eq!(cur.prev_inst(), Some(i1));
1184            assert_eq!(cur.prev_inst(), None);
1185            assert_eq!(cur.prev_block(), None);
1186        }
1187
1188        // Check `ProgramOrder`.
1189        assert_eq!(layout.pp_cmp(e2, e2), Ordering::Equal);
1190        assert_eq!(layout.pp_cmp(e2, i2), Ordering::Less);
1191        assert_eq!(layout.pp_cmp(i3, i2), Ordering::Greater)
1192    }
1193}
cranelift_codegen/ir/layout.rs

cranelift_codegen/ir/
layout.rs
