1use std::collections::{BTreeMap, BTreeSet, VecDeque};
8use std::fmt;
9use std::hash::Hash;
10
11use super::FunctionAllocationFacts;
12
13#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
14struct DefinitionSite {
15 block: usize,
16 instruction: Option<usize>,
17 slot: u64,
18}
19
20#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
21struct UseSite {
22 block: usize,
23 instruction: Option<usize>,
24 slot: u64,
25}
26
27#[derive(Debug, Clone, Copy, PartialEq, Eq)]
29pub struct LiveSegment {
30 pub block: usize,
31 pub start: u64,
32 pub end: u64,
33}
34
35impl LiveSegment {
36 pub fn contains(self, point: u64) -> bool {
37 self.start <= point && point < self.end
38 }
39
40 pub fn overlaps(self, other: Self) -> bool {
41 self.block == other.block && self.start < other.end && other.start < self.end
42 }
43}
44
45#[derive(Debug, Clone, PartialEq, Eq)]
47pub struct LiveInterval<V> {
48 pub value: V,
49 pub segments: Vec<LiveSegment>,
50}
51
52impl<V> LiveInterval<V> {
53 pub fn segment_in_block(&self, block: usize) -> Option<LiveSegment> {
54 self.segments
55 .binary_search_by_key(&block, |segment| segment.block)
56 .ok()
57 .map(|index| self.segments[index])
58 }
59
60 pub fn interferes(&self, other: &Self) -> bool {
61 let mut left = 0;
62 let mut right = 0;
63 while left < self.segments.len() && right < other.segments.len() {
64 let a = self.segments[left];
65 let b = other.segments[right];
66 if a.overlaps(b) {
67 return true;
68 }
69 if (a.block, a.end) <= (b.block, b.end) {
70 left += 1;
71 } else {
72 right += 1;
73 }
74 }
75 false
76 }
77}
78
79#[derive(Debug, Clone, PartialEq, Eq)]
81pub struct LiveIntervals<V> {
82 intervals: BTreeMap<V, LiveInterval<V>>,
83 live_in: Vec<BTreeSet<V>>,
84 live_out: Vec<BTreeSet<V>>,
85}
86
87impl<V: Ord> LiveIntervals<V> {
88 pub fn get(&self, value: &V) -> Option<&LiveInterval<V>> {
89 self.intervals.get(value)
90 }
91
92 pub fn iter(&self) -> impl Iterator<Item = (&V, &LiveInterval<V>)> {
93 self.intervals.iter()
94 }
95
96 pub fn live_in(&self, block: usize) -> Option<&BTreeSet<V>> {
97 self.live_in.get(block)
98 }
99
100 pub fn live_out(&self, block: usize) -> Option<&BTreeSet<V>> {
101 self.live_out.get(block)
102 }
103}
104
105#[derive(Debug, Clone, PartialEq, Eq)]
107pub struct LiveIntervalError<V> {
108 pub rule: &'static str,
109 pub block: Option<usize>,
110 pub instruction: Option<usize>,
111 pub values: Vec<V>,
112 pub message: String,
113}
114
115impl<V> LiveIntervalError<V> {
116 fn new(
117 rule: &'static str,
118 block: Option<usize>,
119 instruction: Option<usize>,
120 values: Vec<V>,
121 message: impl Into<String>,
122 ) -> Self {
123 Self {
124 rule,
125 block,
126 instruction,
127 values,
128 message: message.into(),
129 }
130 }
131}
132
133impl<V: fmt::Debug> fmt::Display for LiveIntervalError<V> {
134 fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
135 write!(formatter, "{}", self.rule)?;
136 if let Some(block) = self.block {
137 write!(formatter, " at block {block}")?;
138 }
139 if let Some(instruction) = self.instruction {
140 write!(formatter, "/i{instruction}")?;
141 }
142 if !self.values.is_empty() {
143 write!(formatter, " values={:?}", self.values)?;
144 }
145 write!(formatter, ": {}", self.message)
146 }
147}
148
149impl<V: fmt::Debug> std::error::Error for LiveIntervalError<V> {}
150
151struct BlockFacts<V> {
152 definitions: BTreeSet<V>,
153 upward_uses: BTreeSet<V>,
154 last_use: BTreeMap<V, u64>,
155}
156
157impl<V> Default for BlockFacts<V> {
158 fn default() -> Self {
159 Self {
160 definitions: BTreeSet::new(),
161 upward_uses: BTreeSet::new(),
162 last_use: BTreeMap::new(),
163 }
164 }
165}
166
167struct ModelFacts<V> {
168 definitions: BTreeMap<V, DefinitionSite>,
169 uses: BTreeMap<V, Vec<UseSite>>,
170 blocks: Vec<BlockFacts<V>>,
171 edge_uses: BTreeMap<(usize, usize), BTreeSet<V>>,
172}
173
174#[derive(Debug, Clone, Copy, PartialEq, Eq)]
175struct BlockSlots {
176 phi_def: u64,
177 exit: u64,
178}
179
180fn instruction_use_slot(instruction: usize) -> Option<u64> {
181 u64::try_from(instruction)
182 .ok()?
183 .checked_mul(3)?
184 .checked_add(2)
185}
186
187fn instruction_def_slot(instruction: usize) -> Option<u64> {
188 instruction_use_slot(instruction)?.checked_add(2)
189}
190
191fn block_slots<V, R>(
192 facts: &FunctionAllocationFacts<V, R>,
193) -> Result<Vec<BlockSlots>, LiveIntervalError<V>> {
194 facts
195 .blocks
196 .iter()
197 .enumerate()
198 .map(|(block, facts)| {
199 let exit = u64::try_from(facts.instructions.len())
200 .ok()
201 .and_then(|count| count.checked_mul(3))
202 .and_then(|slot| slot.checked_add(2))
203 .ok_or_else(|| {
204 LiveIntervalError::new(
205 "LIVE_INTERVAL.SLOT_RANGE",
206 Some(block),
207 None,
208 Vec::new(),
209 "block exit is outside the program-point domain",
210 )
211 })?;
212 Ok(BlockSlots { phi_def: 1, exit })
213 })
214 .collect()
215}
216
217fn record_definition<V: Copy + Ord>(
218 definitions: &mut BTreeMap<V, DefinitionSite>,
219 value: V,
220 site: DefinitionSite,
221) -> Result<(), LiveIntervalError<V>> {
222 if let Some(previous) = definitions.insert(value, site) {
223 return Err(LiveIntervalError::new(
224 "LIVE_INTERVAL.MULTIPLE_DEFINITIONS",
225 Some(site.block),
226 site.instruction,
227 vec![value],
228 format!("value was already defined at {previous:?}"),
229 ));
230 }
231 Ok(())
232}
233
234fn collect_model<V, R>(
235 facts: &FunctionAllocationFacts<V, R>,
236 predecessors: &[Vec<usize>],
237 slots: &[BlockSlots],
238) -> Result<ModelFacts<V>, LiveIntervalError<V>>
239where
240 V: Copy + Ord,
241{
242 let mut definitions = BTreeMap::new();
243 let mut uses = BTreeMap::<V, Vec<UseSite>>::new();
244 let mut blocks = (0..facts.blocks.len())
245 .map(|_| BlockFacts::default())
246 .collect::<Vec<_>>();
247
248 for (block_index, block) in facts.blocks.iter().enumerate() {
249 for phi in &block.phis {
250 let site = DefinitionSite {
251 block: block_index,
252 instruction: None,
253 slot: slots[block_index].phi_def,
254 };
255 record_definition(&mut definitions, phi.destination, site)?;
256 blocks[block_index].definitions.insert(phi.destination);
257 }
258
259 let mut seen_definitions = blocks[block_index].definitions.clone();
260 for (instruction_index, instruction) in block.instructions.iter().enumerate() {
261 let use_slot = instruction_use_slot(instruction_index).ok_or_else(|| {
262 LiveIntervalError::new(
263 "LIVE_INTERVAL.SLOT_RANGE",
264 Some(block_index),
265 Some(instruction_index),
266 Vec::new(),
267 "instruction use is outside the program-point domain",
268 )
269 })?;
270 let mut instruction_uses = instruction.uses.clone();
271 instruction_uses.sort_unstable();
272 instruction_uses.dedup();
273 for value in instruction_uses {
274 let site = UseSite {
275 block: block_index,
276 instruction: Some(instruction_index),
277 slot: use_slot,
278 };
279 uses.entry(value).or_default().push(site);
280 if !seen_definitions.contains(&value) {
281 blocks[block_index].upward_uses.insert(value);
282 }
283 blocks[block_index]
284 .last_use
285 .entry(value)
286 .and_modify(|current| *current = (*current).max(use_slot))
287 .or_insert(use_slot);
288 }
289 let def_slot = instruction_def_slot(instruction_index).ok_or_else(|| {
290 LiveIntervalError::new(
291 "LIVE_INTERVAL.SLOT_RANGE",
292 Some(block_index),
293 Some(instruction_index),
294 Vec::new(),
295 "instruction definition is outside the program-point domain",
296 )
297 })?;
298 for &value in &instruction.defs {
299 let site = DefinitionSite {
300 block: block_index,
301 instruction: Some(instruction_index),
302 slot: def_slot,
303 };
304 record_definition(&mut definitions, value, site)?;
305 blocks[block_index].definitions.insert(value);
306 seen_definitions.insert(value);
307 }
308 }
309 }
310
311 let mut edge_uses = BTreeMap::<(usize, usize), BTreeSet<V>>::new();
312 for (successor, block) in facts.blocks.iter().enumerate() {
313 for phi in &block.phis {
314 let mut seen_predecessors = BTreeSet::new();
315 for source in &phi.sources {
316 if !seen_predecessors.insert(source.predecessor) {
317 return Err(LiveIntervalError::new(
318 "LIVE_INTERVAL.PHI_PREDECESSOR",
319 Some(successor),
320 None,
321 vec![source.value],
322 "phi predecessor appears more than once",
323 ));
324 }
325 let site = UseSite {
326 block: source.predecessor,
327 instruction: None,
328 slot: slots[source.predecessor].exit,
329 };
330 uses.entry(source.value).or_default().push(site);
331 edge_uses
332 .entry((source.predecessor, successor))
333 .or_default()
334 .insert(source.value);
335 blocks[source.predecessor]
336 .last_use
337 .entry(source.value)
338 .and_modify(|current| *current = (*current).max(site.slot))
339 .or_insert(site.slot);
340 }
341 if seen_predecessors.len() != predecessors[successor].len() {
342 return Err(LiveIntervalError::new(
343 "LIVE_INTERVAL.PHI_PREDECESSOR",
344 Some(successor),
345 None,
346 vec![phi.destination],
347 "phi does not provide exactly one source for every predecessor",
348 ));
349 }
350 }
351 }
352 for sites in uses.values_mut() {
353 sites.sort_unstable();
354 sites.dedup();
355 }
356
357 Ok(ModelFacts {
358 definitions,
359 uses,
360 blocks,
361 edge_uses,
362 })
363}
364
365fn solve_liveness<V: Copy + Ord, R>(
366 facts: &FunctionAllocationFacts<V, R>,
367 predecessors: &[Vec<usize>],
368 model: &ModelFacts<V>,
369) -> (Vec<BTreeSet<V>>, Vec<BTreeSet<V>>) {
370 let mut live_in = vec![BTreeSet::new(); facts.blocks.len()];
371 let mut live_out = live_in.clone();
372 let mut queue = (0..facts.blocks.len()).rev().collect::<VecDeque<_>>();
373 let mut queued = vec![true; facts.blocks.len()];
374 while let Some(block) = queue.pop_front() {
375 queued[block] = false;
376 let mut next_out = BTreeSet::new();
377 for &successor in &facts.blocks[block].successors {
378 next_out.extend(live_in[successor].iter().copied());
379 if let Some(edge) = model.edge_uses.get(&(block, successor)) {
380 next_out.extend(edge.iter().copied());
381 }
382 }
383 let mut next_in = model.blocks[block].upward_uses.clone();
384 next_in.extend(
385 next_out
386 .iter()
387 .copied()
388 .filter(|value| !model.blocks[block].definitions.contains(value)),
389 );
390 if next_in != live_in[block] || next_out != live_out[block] {
391 live_in[block] = next_in;
392 live_out[block] = next_out;
393 for &predecessor in &predecessors[block] {
394 if !queued[predecessor] {
395 queued[predecessor] = true;
396 queue.push_back(predecessor);
397 }
398 }
399 }
400 }
401 (live_in, live_out)
402}
403
404struct DominatorTree {
405 enter: Vec<usize>,
406 exit: Vec<usize>,
407}
408
409impl DominatorTree {
410 fn dominates(&self, dominator: usize, block: usize) -> bool {
411 self.enter[dominator] <= self.enter[block] && self.exit[block] <= self.exit[dominator]
412 }
413}
414
415fn compute_dominators<V>(
416 entry: usize,
417 successors: &[Vec<usize>],
418 predecessors: &[Vec<usize>],
419) -> Result<DominatorTree, LiveIntervalError<V>> {
420 let mut reachable = vec![false; successors.len()];
421 let mut postorder = Vec::with_capacity(successors.len());
422 let mut stack = vec![(entry, 0usize)];
423 reachable[entry] = true;
424 while let Some((block, next_successor)) = stack.last_mut() {
425 if *next_successor == successors[*block].len() {
426 postorder.push(*block);
427 stack.pop();
428 } else {
429 let successor = successors[*block][*next_successor];
430 *next_successor += 1;
431 if !reachable[successor] {
432 reachable[successor] = true;
433 stack.push((successor, 0));
434 }
435 }
436 }
437 if let Some(block) = reachable.iter().position(|reachable| !reachable) {
438 return Err(LiveIntervalError::new(
439 "LIVE_INTERVAL.UNREACHABLE_BLOCK",
440 Some(block),
441 None,
442 Vec::new(),
443 "allocation facts contain a block unreachable from the entry",
444 ));
445 }
446
447 postorder.reverse();
448 let mut rpo_position = vec![0; successors.len()];
449 for (position, &block) in postorder.iter().enumerate() {
450 rpo_position[block] = position;
451 }
452 let mut idom = vec![None; successors.len()];
453 idom[entry] = Some(entry);
454 let mut changed = true;
455 while changed {
456 changed = false;
457 for &block in postorder.iter().skip(1) {
458 let mut processed = predecessors[block]
459 .iter()
460 .copied()
461 .filter(|predecessor| idom[*predecessor].is_some());
462 let mut next = processed.next().ok_or_else(|| {
463 LiveIntervalError::new(
464 "LIVE_INTERVAL.DOMINATOR_TREE",
465 Some(block),
466 None,
467 Vec::new(),
468 "reachable block has no processed predecessor",
469 )
470 })?;
471 for predecessor in processed {
472 next = intersect_dominators(next, predecessor, &idom, &rpo_position);
473 }
474 if idom[block] != Some(next) {
475 idom[block] = Some(next);
476 changed = true;
477 }
478 }
479 }
480 idom[entry] = None;
481
482 let mut children = vec![Vec::new(); successors.len()];
483 for (block, parent) in idom.iter().copied().enumerate() {
484 if let Some(parent) = parent {
485 children[parent].push(block);
486 }
487 }
488 let mut enter = vec![0; successors.len()];
489 let mut exit = vec![0; successors.len()];
490 let mut clock = 0usize;
491 let mut stack = vec![(entry, false)];
492 while let Some((block, leaving)) = stack.pop() {
493 if leaving {
494 exit[block] = clock;
495 clock += 1;
496 } else {
497 enter[block] = clock;
498 clock += 1;
499 stack.push((block, true));
500 stack.extend(children[block].iter().rev().map(|&child| (child, false)));
501 }
502 }
503 Ok(DominatorTree { enter, exit })
504}
505
506fn intersect_dominators(
507 mut left: usize,
508 mut right: usize,
509 idom: &[Option<usize>],
510 rpo_position: &[usize],
511) -> usize {
512 while left != right {
513 while rpo_position[left] > rpo_position[right] {
514 left = idom[left].expect("processed dominator must have a parent");
515 }
516 while rpo_position[right] > rpo_position[left] {
517 right = idom[right].expect("processed dominator must have a parent");
518 }
519 }
520 left
521}
522
523pub fn analyze_live_intervals<V, R>(
525 facts: &FunctionAllocationFacts<V, R>,
526) -> Result<LiveIntervals<V>, LiveIntervalError<V>>
527where
528 V: Copy + Eq + Hash + Ord + fmt::Debug,
529{
530 facts.verify().map_err(|error| {
531 LiveIntervalError::new(
532 "LIVE_INTERVAL.ALLOCATION_FACTS",
533 None,
534 None,
535 Vec::new(),
536 error.to_string(),
537 )
538 })?;
539 let mut predecessors = vec![Vec::new(); facts.blocks.len()];
540 for (block, facts) in facts.blocks.iter().enumerate() {
541 for &successor in &facts.successors {
542 predecessors[successor].push(block);
543 }
544 }
545 let successors = facts
546 .blocks
547 .iter()
548 .map(|block| block.successors.clone())
549 .collect::<Vec<_>>();
550 let dominators = compute_dominators(facts.entry, &successors, &predecessors)?;
551 let slots = block_slots(facts)?;
552 let model = collect_model(facts, &predecessors, &slots)?;
553 let (live_in, live_out) = solve_liveness(facts, &predecessors, &model);
554 let mut segments = BTreeMap::<V, Vec<LiveSegment>>::new();
555
556 for block in 0..facts.blocks.len() {
557 let mut values = BTreeSet::new();
558 values.extend(live_in[block].iter().copied());
559 values.extend(live_out[block].iter().copied());
560 values.extend(model.blocks[block].definitions.iter().copied());
561 values.extend(model.blocks[block].last_use.keys().copied());
562 for value in values {
563 let Some(definition) = model.definitions.get(&value).copied() else {
564 return Err(LiveIntervalError::new(
565 "LIVE_INTERVAL.MISSING_DEFINITION",
566 Some(block),
567 None,
568 vec![value],
569 "live or used value has no target-MIR definition",
570 ));
571 };
572 if definition.block == block && live_in[block].contains(&value) {
573 return Err(LiveIntervalError::new(
574 "LIVE_INTERVAL.USE_BEFORE_DEFINITION",
575 Some(block),
576 definition.instruction,
577 vec![value],
578 "value is live at entry of its defining block",
579 ));
580 }
581 let start = if definition.block == block {
582 definition.slot
583 } else {
584 0
585 };
586 let end = if live_out[block].contains(&value) {
587 slots[block].exit.checked_add(1)
588 } else if let Some(last_use) = model.blocks[block].last_use.get(&value) {
589 last_use.checked_add(1)
590 } else if definition.block == block {
591 definition.slot.checked_add(1)
592 } else {
593 None
594 }
595 .ok_or_else(|| {
596 LiveIntervalError::new(
597 "LIVE_INTERVAL.SLOT_RANGE",
598 Some(block),
599 None,
600 vec![value],
601 "live segment end overflows or has no local reason to exist",
602 )
603 })?;
604 if start >= end {
605 return Err(LiveIntervalError::new(
606 "LIVE_INTERVAL.EMPTY_SEGMENT",
607 Some(block),
608 None,
609 vec![value],
610 format!("segment {start}..{end} is empty or reversed"),
611 ));
612 }
613 segments
614 .entry(value)
615 .or_default()
616 .push(LiveSegment { block, start, end });
617 }
618 }
619
620 let mut intervals = BTreeMap::new();
621 for (&value, &definition) in &model.definitions {
622 let mut value_segments = segments.remove(&value).unwrap_or_default();
623 value_segments.sort_unstable_by_key(|segment| (segment.block, segment.start));
624 let interval = LiveInterval {
625 value,
626 segments: value_segments,
627 };
628 if !interval
629 .segment_in_block(definition.block)
630 .is_some_and(|segment| segment.contains(definition.slot))
631 {
632 return Err(LiveIntervalError::new(
633 "LIVE_INTERVAL.DEFINITION_COVERAGE",
634 Some(definition.block),
635 definition.instruction,
636 vec![value],
637 "definition is not covered by its live interval",
638 ));
639 }
640 for site in model.uses.get(&value).into_iter().flatten() {
641 let covered = interval
642 .segment_in_block(site.block)
643 .is_some_and(|segment| segment.contains(site.slot));
644 let dominated = if definition.block == site.block {
645 definition.slot < site.slot
646 } else {
647 dominators.dominates(definition.block, site.block)
648 };
649 if !covered || !dominated {
650 return Err(LiveIntervalError::new(
651 "LIVE_INTERVAL.DEFINITION_DOMINANCE",
652 Some(site.block),
653 site.instruction,
654 vec![value],
655 "definition does not dominate the target-MIR use",
656 ));
657 }
658 }
659 intervals.insert(value, interval);
660 }
661 if let Some((&value, sites)) = model
662 .uses
663 .iter()
664 .find(|(value, _)| !model.definitions.contains_key(value))
665 {
666 return Err(LiveIntervalError::new(
667 "LIVE_INTERVAL.MISSING_DEFINITION",
668 sites.first().map(|site| site.block),
669 sites.first().and_then(|site| site.instruction),
670 vec![value],
671 "used value has no target-MIR definition",
672 ));
673 }
674
675 Ok(LiveIntervals {
676 intervals,
677 live_in,
678 live_out,
679 })
680}
681
682#[cfg(test)]
683mod tests {
684 use super::*;
685 use crate::regalloc::{
686 BlockAllocationFacts, InstructionAllocationFacts, InstructionConstraints,
687 PhiAllocationFacts, PhiSource,
688 };
689
690 fn instruction(uses: Vec<u32>, defs: Vec<u32>) -> InstructionAllocationFacts<u32, ()> {
691 InstructionAllocationFacts {
692 uses,
693 defs,
694 constraints: InstructionConstraints::default(),
695 is_copy: false,
696 }
697 }
698
699 #[test]
700 fn diamond_arms_remain_non_interfering() {
701 let facts = FunctionAllocationFacts {
702 entry: 0,
703 blocks: vec![
704 BlockAllocationFacts {
705 successors: vec![1, 2],
706 phis: Vec::new(),
707 instructions: vec![instruction(Vec::new(), vec![0])],
708 },
709 BlockAllocationFacts {
710 successors: vec![3],
711 phis: Vec::new(),
712 instructions: vec![instruction(vec![0], vec![1])],
713 },
714 BlockAllocationFacts {
715 successors: vec![3],
716 phis: Vec::new(),
717 instructions: vec![instruction(vec![0], vec![2])],
718 },
719 BlockAllocationFacts {
720 successors: Vec::new(),
721 phis: vec![PhiAllocationFacts {
722 destination: 3,
723 sources: vec![
724 PhiSource {
725 predecessor: 1,
726 value: 1,
727 },
728 PhiSource {
729 predecessor: 2,
730 value: 2,
731 },
732 ],
733 }],
734 instructions: vec![instruction(vec![3], Vec::new())],
735 },
736 ],
737 };
738
739 let intervals = analyze_live_intervals(&facts).unwrap();
740 assert!(
741 !intervals
742 .get(&1)
743 .unwrap()
744 .interferes(intervals.get(&2).unwrap())
745 );
746 assert!(intervals.live_out(1).unwrap().contains(&1));
747 assert!(intervals.live_out(2).unwrap().contains(&2));
748 assert!(!intervals.live_in(3).unwrap().contains(&1));
749 }
750
751 #[test]
752 fn rejects_missing_phi_source() {
753 let facts = FunctionAllocationFacts::<u32, ()> {
754 entry: 0,
755 blocks: vec![
756 BlockAllocationFacts {
757 successors: vec![1, 2],
758 phis: Vec::new(),
759 instructions: vec![instruction(Vec::new(), vec![0])],
760 },
761 BlockAllocationFacts {
762 successors: vec![2],
763 phis: Vec::new(),
764 instructions: vec![instruction(Vec::new(), vec![1])],
765 },
766 BlockAllocationFacts {
767 successors: Vec::new(),
768 phis: vec![PhiAllocationFacts {
769 destination: 2,
770 sources: vec![PhiSource {
771 predecessor: 0,
772 value: 0,
773 }],
774 }],
775 instructions: Vec::new(),
776 },
777 ],
778 };
779
780 assert_eq!(
781 analyze_live_intervals(&facts).unwrap_err().rule,
782 "LIVE_INTERVAL.PHI_PREDECESSOR"
783 );
784 }
785
786 #[test]
787 fn rejects_use_before_definition() {
788 let facts = FunctionAllocationFacts::<u32, ()> {
789 entry: 0,
790 blocks: vec![BlockAllocationFacts {
791 successors: Vec::new(),
792 phis: Vec::new(),
793 instructions: vec![
794 instruction(vec![0], Vec::new()),
795 instruction(Vec::new(), vec![0]),
796 ],
797 }],
798 };
799
800 assert_eq!(
801 analyze_live_intervals(&facts).unwrap_err().rule,
802 "LIVE_INTERVAL.USE_BEFORE_DEFINITION"
803 );
804 }
805}