Experiment: Try Motoko Debugger

[Kamirus]

Do not merge: Just an experiment of using the motoko_debugger in the new-base

Cases I wanted to test:

• Simple main-program with mops sources
• Debugging tests

Check out this branch locally and try one of the changed files. See the instructions below.

Update:
I've tried the debugger with this moc fix to the debug section and I can say that it works pretty well on these 3 files in this PR and it runs on the List.test.mo as well

Current limitations that I've found:

• Most test files e.g. test/List.test.mo do not work and fail with index out of bounds: the len is 27 but the index is 30, seems like bigger wasms are problematic
• The list command (and transitively other commands e.g. thread step-in with similar output): sometimes produces wrong output. The code line shown might not correspond to the actual one. See the changed files.
  • This is probably due to wrong debug section encoding on the moc side
• Use of mops packages break the list output, frequent File not found: "./internals"
• read local works great for primitives but complex types like objects are just memory addresses.
• No vscode integration yet

How to run

Setup motoko debugger:

• git clone https://github.com/scalebit/motoko_debugger to ~/motoko_debugger
• cd ~/motoko_debugger && cargo build --release

Run, e.g. src/SimpleDebuggerTest.mo:

• moc $(mops sources) -o MoDe.wasm -g src/SimpleDebuggerTest.mo && ~/motoko_debugger/target/release/debugger MoDe.wasm
• Or using custom-built moc:
  • cd ~/motoko && nix develop
  • cd ~/motoko-core
  • make -C ../motoko/src moc && moc $(mops sources) -o MoDe.wasm -g --legacy-persistence src/SimpleDebuggerTest.mo && ~/motoko_debugger/target/release/debugger MoDe.wasm

[github-actions]

✨ Documentation preview for 2864fae:

https://dfinity.github.io/motoko-core/pull/327 (source code)

[github-actions]

Benchmark Results

bench/ArrayBuilding.bench.mo $({\color{gray}0\%})$

Large known-size array building

Compares performance of different data structures for building arrays of known size.

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Instructions

	1000	100000	1000000
List	548_233 $({\color{gray}0\%})$	48_324_535 $({\color{gray}0\%})$	478_161_875 $({\color{gray}0\%})$
Buffer	342_005 $({\color{gray}0\%})$	33_903_435 $({\color{gray}0\%})$	339_003_650 $({\color{gray}0\%})$
pure/List	302_135 $({\color{gray}0\%})$	30_003_590 $({\color{gray}0\%})$	300_055_972 $({\color{gray}0\%})$
VarArray ?T	180_526 $({\color{gray}0\%})$	17_802_956 $({\color{gray}0\%})$	178_003_171 $({\color{gray}0\%})$
VarArray T	160_813 $({\color{gray}0\%})$	15_803_243 $({\color{gray}0\%})$	158_003_458 $({\color{gray}0\%})$
Array (baseline)	42_695 $({\color{gray}0\%})$	4_003_125 $({\color{gray}0\%})$	40_003_340 $({\color{gray}0\%})$

Heap

	1000	100000	1000000
List	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$
Buffer	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$
pure/List	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$
VarArray ?T	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$
VarArray T	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$
Array (baseline)	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$

Garbage Collection

	1000	100000	1000000
List	10.05 KiB $({\color{gray}0\%})$	797.56 KiB $({\color{gray}0\%})$	7.67 MiB $({\color{gray}0\%})$
Buffer	8.71 KiB $({\color{gray}0\%})$	782.15 KiB $({\color{gray}0\%})$	7.63 MiB $({\color{gray}0\%})$
pure/List	19.95 KiB $({\color{gray}0\%})$	1.91 MiB $({\color{gray}0\%})$	19.07 MiB $({\color{gray}0\%})$
VarArray ?T	8.24 KiB $({\color{gray}0\%})$	781.68 KiB $({\color{gray}0\%})$	7.63 MiB $({\color{gray}0\%})$
VarArray T	8.23 KiB $({\color{gray}0\%})$	781.67 KiB $({\color{gray}0\%})$	7.63 MiB $({\color{gray}0\%})$
Array (baseline)	4.3 KiB $({\color{gray}0\%})$	391.02 KiB $({\color{gray}0\%})$	3.82 MiB $({\color{gray}0\%})$

bench/FromIters.bench.mo $({\color{gray}0\%})$

Benchmarking the fromIter functions

Columns describe the number of elements in the input iter.

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Instructions

	100	10_000	100_000
Array.fromIter	48_764 $({\color{gray}0\%})$	4_712_025 $({\color{gray}0\%})$	47_103_135 $({\color{gray}0\%})$
List.fromIter	31_698 $({\color{gray}0\%})$	3_061_541 $({\color{gray}0\%})$	30_603_553 $({\color{gray}0\%})$
List.fromIter . Iter.reverse	50_297 $({\color{gray}0\%})$	4_832_522 $({\color{gray}0\%})$	48_305_436 $({\color{gray}0\%})$

Heap

	100	10_000	100_000
Array.fromIter	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$
List.fromIter	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$
List.fromIter . Iter.reverse	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$

Garbage Collection

	100	10_000	100_000
Array.fromIter	2.76 KiB $({\color{gray}0\%})$	234.79 KiB $({\color{gray}0\%})$	2.29 MiB $({\color{gray}0\%})$
List.fromIter	3.51 KiB $({\color{gray}0\%})$	312.88 KiB $({\color{gray}0\%})$	3.05 MiB $({\color{gray}0\%})$
List.fromIter . Iter.reverse	5.11 KiB $({\color{gray}0\%})$	469.17 KiB $({\color{gray}0\%})$	4.58 MiB $({\color{gray}0\%})$

bench/ListBufferNewArray.bench.mo $({\color{gray}0\%})$

List vs. Buffer for creating known-size arrays

Performance comparison between List and Buffer for creating a new array.

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Instructions

	0 (baseline)	1	5	10	100 (for loop)
List	1_547 $({\color{gray}0\%})$	2_916 $({\color{gray}0\%})$	9_046 $({\color{gray}0\%})$	13_948 $({\color{gray}0\%})$	74_564 $({\color{gray}0\%})$
pure/List	1_247 $({\color{gray}0\%})$	1_355 $({\color{gray}0\%})$	2_439 $({\color{gray}0\%})$	3_801 $({\color{gray}0\%})$	31_868 $({\color{gray}0\%})$
Buffer	2_119 $({\color{gray}0\%})$	2_271 $({\color{gray}0\%})$	3_518 $({\color{gray}0\%})$	5_085 $({\color{gray}0\%})$	36_640 $({\color{gray}0\%})$

Heap

	0 (baseline)	1	5	10	100 (for loop)
List	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$
pure/List	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$
Buffer	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$	272 B $({\color{gray}0\%})$

Garbage Collection

	0 (baseline)	1	5	10	100 (for loop)
List	576 B $({\color{gray}0\%})$	616 B $({\color{gray}0\%})$	776 B $({\color{gray}0\%})$	884 B $({\color{gray}0\%})$	1.93 KiB $({\color{gray}0\%})$
pure/List	360 B $({\color{gray}0\%})$	380 B $({\color{gray}0\%})$	460 B $({\color{gray}0\%})$	560 B $({\color{gray}0\%})$	2.3 KiB $({\color{gray}0\%})$
Buffer	856 B $({\color{gray}0\%})$	864 B $({\color{gray}0\%})$	896 B $({\color{gray}0\%})$	936 B $({\color{gray}0\%})$	1.62 KiB $({\color{gray}0\%})$

bench/PureListStackSafety.bench.mo $({\color{gray}0\%})$

List Stack safety

Check stack-safety of the following pure/List-related functions.

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Instructions

pure/List.split	24_602_524 $({\color{gray}0\%})$
pure/List.all	7_901_014 $({\color{gray}0\%})$
pure/List.any	8_001_390 $({\color{gray}0\%})$
pure/List.map	23_103_767 $({\color{gray}0\%})$
pure/List.filter	21_104_188 $({\color{gray}0\%})$
pure/List.filterMap	27_404_742 $({\color{gray}0\%})$
pure/List.partition	21_304_994 $({\color{gray}0\%})$
pure/List.join	33_105_326 $({\color{gray}0\%})$
pure/List.flatten	24_805_667 $({\color{gray}0\%})$
pure/List.take	24_605_664 $({\color{gray}0\%})$
pure/List.drop	9_904_119 $({\color{gray}0\%})$
pure/List.foldRight	19_105_768 $({\color{gray}0\%})$
pure/List.merge	31_808_584 $({\color{gray}0\%})$
pure/List.chunks	51_510_344 $({\color{gray}0\%})$
pure/Queue	140_562_492 $({\color{gray}0\%})$

Heap

pure/List.split	272 B $({\color{gray}0\%})$
pure/List.all	272 B $({\color{gray}0\%})$
pure/List.any	272 B $({\color{gray}0\%})$
pure/List.map	272 B $({\color{gray}0\%})$
pure/List.filter	272 B $({\color{gray}0\%})$
pure/List.filterMap	272 B $({\color{gray}0\%})$
pure/List.partition	272 B $({\color{gray}0\%})$
pure/List.join	272 B $({\color{gray}0\%})$
pure/List.flatten	272 B $({\color{gray}0\%})$
pure/List.take	272 B $({\color{gray}0\%})$
pure/List.drop	272 B $({\color{gray}0\%})$
pure/List.foldRight	272 B $({\color{gray}0\%})$
pure/List.merge	272 B $({\color{gray}0\%})$
pure/List.chunks	272 B $({\color{gray}0\%})$
pure/Queue	272 B $({\color{gray}0\%})$

Garbage Collection

pure/List.split	3.05 MiB $({\color{gray}0\%})$
pure/List.all	328 B $({\color{gray}0\%})$
pure/List.any	328 B $({\color{gray}0\%})$
pure/List.map	3.05 MiB $({\color{gray}0\%})$
pure/List.filter	3.05 MiB $({\color{gray}0\%})$
pure/List.filterMap	3.05 MiB $({\color{gray}0\%})$
pure/List.partition	3.05 MiB $({\color{gray}0\%})$
pure/List.join	3.05 MiB $({\color{gray}0\%})$
pure/List.flatten	3.05 MiB $({\color{gray}0\%})$
pure/List.take	3.05 MiB $({\color{gray}0\%})$
pure/List.drop	328 B $({\color{gray}0\%})$
pure/List.foldRight	1.53 MiB $({\color{gray}0\%})$
pure/List.merge	4.58 MiB $({\color{gray}0\%})$
pure/List.chunks	7.63 MiB $({\color{gray}0\%})$
pure/Queue	18.31 MiB $({\color{gray}0\%})$

bench/Queues.bench.mo $({\color{gray}0\%})$

Different queue implementations

Compare the performance of the following queue implementations:

• pure/Queue: The default immutable double-ended queue implementation.
  • Pros: Good amortized performance, meaning that the average cost of operations is low O(1).
  • Cons: In worst case, an operation can take O(size) time rebuilding the queue as demonstrated in the Pop front 2 elements scenario.
• pure/RealTimeQueue
  • Pros: Every operation is guaranteed to take at most O(1) time and space.
  • Cons: Poor amortized performance: Instruction cost is on average 3x for pop and 8x for push compared to pure/Queue.
• mutable Queue
  • Pros: Also O(1) guarantees with a lower constant factor than pure/RealTimeQueue. Amortized performance is comparable to pure/Queue.
  • Cons: It is mutable and cannot be used in shared types (not shareable).

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Instructions

	pure/Queue	pure/RealTimeQueue	mutable Queue
Initialize with 2 elements	3_092 $({\color{gray}0\%})$	2_304 $({\color{gray}0\%})$	3_040 $({\color{gray}0\%})$
Push 500 elements	90_713 $({\color{gray}0\%})$	744_219 $({\color{gray}0\%})$	219_284 $({\color{gray}0\%})$
Pop front 2 elements	86_966 $({\color{gray}0\%})$	4_446 $({\color{gray}0\%})$	3_847 $({\color{gray}0\%})$
Pop 150 front&back	92_074 $({\color{gray}0\%})$	304_887 $({\color{gray}0\%})$	124_560 $({\color{gray}0\%})$

Heap

	pure/Queue	pure/RealTimeQueue	mutable Queue
Initialize with 2 elements	324 B $({\color{gray}0\%})$	300 B $({\color{gray}0\%})$	352 B $({\color{gray}0\%})$
Push 500 elements	8.08 KiB $({\color{gray}0\%})$	8.17 KiB $({\color{gray}0\%})$	19.8 KiB $({\color{gray}0\%})$
Pop front 2 elements	240 B $({\color{gray}0\%})$	240 B $({\color{gray}0\%})$	192 B $({\color{gray}0\%})$
Pop 150 front&back	-4.42 KiB $({\color{gray}0\%})$	-492 B $({\color{gray}0\%})$	-11.45 KiB $({\color{gray}0\%})$

Garbage Collection

	pure/Queue	pure/RealTimeQueue	mutable Queue
Initialize with 2 elements	508 B $({\color{gray}0\%})$	444 B $({\color{gray}0\%})$	456 B $({\color{gray}0\%})$
Push 500 elements	10.1 KiB $({\color{gray}0\%})$	137.84 KiB $({\color{gray}0\%})$	344 B $({\color{gray}0\%})$
Pop front 2 elements	12.19 KiB $({\color{gray}0\%})$	528 B $({\color{gray}0\%})$	424 B $({\color{gray}0\%})$
Pop 150 front&back	15.61 KiB $({\color{gray}0\%})$	49.66 KiB $({\color{gray}0\%})$	12.1 KiB $({\color{gray}0\%})$

Note: Renamed benchmarks cannot be compared. Refer to the current baseline for manual comparison.

[rvanasa]

Good idea to try this!