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

cranelift_codegen/ir/
layout.rs
