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Add Instruction and InstructionIterator #3201

Merged
merged 1 commit into from
Sep 6, 2023
Merged

Add Instruction and InstructionIterator #3201

merged 1 commit into from
Sep 6, 2023

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HalidOdat
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This PR adds a fat enum that represents a full instruction (opcode + operands) and an iterator that takes bytecode and produces instructions.

I implemented something like this in #3037, this PR just extracts and refines it.

Why is this useful/needed?

  • It allows us to iterate over instructions without worrying, whether we are reading the operands correctly. Currently we do the same thing in instruction_operands() and flowgraph generation, this is duplicate code and can easily lead to mistakes (also doing it in Implement control flow graph construction #3037 )
  • Extracting the operands is harder when manually accessing bytecode.
  • If we have a list of instructions it's easier to do changes in it.

Note: This is not intended to replace the compact bytecode representation, that is optimized for execution and storage.

... This also makes it easier to implement an bytecode size optimization on operands, that I'm working on ;)

@HalidOdat HalidOdat added enhancement New feature or request Internal Category for changelog labels Aug 5, 2023
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github-actions bot commented Aug 5, 2023 •
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Test262 conformance changes

Test result main count PR count difference
Total 95,368 95,368 0
Passed 75,046 75,046 0
Ignored 19,302 19,302 0
Failed 1,020 1,020 0
Panics 0 0 0
Conformance 78.69% 78.69% 0.00%

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codecov bot commented Aug 5, 2023 •
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Codecov Report

Merging #3201 (cfe700b) into main (dda713d) will decrease coverage by 0.09%.
The diff coverage is 1.88%.

@@            Coverage Diff             @@
##             main    #3201      +/-   ##
==========================================
- Coverage   50.42%   50.34%   -0.09%     
==========================================
  Files         436      436              
  Lines       42549    42618      +69     
==========================================
  Hits        21457    21457              
- Misses      21092    21161      +69
Files Changed Coverage Δ
boa_engine/src/vm/call_frame/mod.rs 90.47% <ø> (ø)
boa_engine/src/vm/code_block.rs 52.99% <0.00%> (-1.51%) ⬇️
boa_engine/src/vm/flowgraph/mod.rs 0.00% <0.00%> (ø)
boa_engine/src/vm/mod.rs 62.50% <ø> (ø)
boa_engine/src/vm/opcode/mod.rs 7.03% <ø> (-62.20%) ⬇️
boa_engine/src/bytecompiler/mod.rs 66.58% <100.00%> (ø)
boa_engine/src/vm/opcode/control_flow/jump.rs 92.68% <100.00%> (ø)

@HalidOdat HalidOdat force-pushed the instruction-iterator branch 2 times, most recently from b952db4 to 776a25b Compare August 5, 2023 06:09
jedel1043
jedel1043 approved these changes Aug 5, 2023
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Really nice improvement! It simplifies our logic a LOT.
Any plans for extending it to Operation implementers or is it just not worth?

boa_engine/src/vm/opcode/mod.rs Outdated Show resolved Hide resolved
@HalidOdat HalidOdat force-pushed the instruction-iterator branch from 776a25b to 9922448 Compare August 6, 2023 04:03
@HalidOdat
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HalidOdat commented Aug 6, 2023 •
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Any plans for extending it to Operation implementers or is it just not worth?

No, this representation is intended for easier bytecode analysis, not really execution, the compact bytecode version is smaller and faster.

@HalidOdat HalidOdat requested a review from a team August 12, 2023 14:13
@HalidOdat HalidOdat added this to the v0.18.0 milestone Aug 12, 2023
nekevss
nekevss reviewed Aug 23, 2023
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boa_engine/src/vm/opcode/mod.rs
}
}

macro_rules! generate_opcodes {
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Should we start writing implementation notes to break down macros?

nekevss
nekevss approved these changes Aug 23, 2023
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Overall looks good to me. Nice work! Just one thought I had while reviewing the macro.

@HalidOdat HalidOdat force-pushed the instruction-iterator branch from 9922448 to b2a8126 Compare August 24, 2023 01:50
@HalidOdat HalidOdat force-pushed the instruction-iterator branch from b2a8126 to cfe700b Compare August 24, 2023 01:52
@HalidOdat HalidOdat mentioned this pull request Sep 3, 2023
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Whats the affect on performance with this change?

@HalidOdat
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HalidOdat commented Sep 5, 2023 •
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Whats the affect on performance with this change?

There is no change in performance, this is doesn't change the way we execute bytecode. It only implements an iterator and the result being an Instruction (opcode + operands). For easier iteration of bytecode, without worrying about the size of operands.

@HalidOdat HalidOdat added this pull request to the merge queue Sep 6, 2023
Merged via the queue into main with commit 3ea0a77 Sep 6, 2023
@HalidOdat HalidOdat deleted the instruction-iterator branch September 7, 2023 07:49
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@nekevss nekevss nekevss approved these changes

@jedel1043 jedel1043 jedel1043 approved these changes

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@HalidOdat @jasonwilliams @jedel1043 @nekevss