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Disable the unpack optimization #1884

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Merged
merged 2 commits into from
Apr 25, 2020
Merged

Disable the unpack optimization #1884

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d7842c7
Disable the unpack optimization
coolreader18 Apr 24, 2020
c50ab85
Add test for unpack regression
coolreader18 Apr 25, 2020
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2 changes: 1 addition & 1 deletion compiler/src/peephole.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -92,7 +92,7 @@ impl<O: OutputStream> PeepholeOptimizer<O> {
}

fn optimize(&mut self) {
apply_optimizations!(self, operator, unpack);
apply_optimizations!(self, operator /* , unpack */);
}
}

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47 changes: 24 additions & 23 deletions compiler/src/peephole/optimizations.rs
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Expand Up @@ -73,26 +73,27 @@ pub fn operator(buf: &mut impl OptimizationBuffer) {
}
}

pub fn unpack(buf: &mut impl OptimizationBuffer) {
let (instruction, meta) = buf.pop();
if let Instruction::UnpackSequence { size } = instruction {
let (arg, arg_meta) = buf.pop();
match arg {
Instruction::BuildTuple {
size: tup_size,
unpack,
} if !unpack && tup_size == size => {
buf.emit(
Instruction::Reverse { amount: size },
vec![arg_meta, meta].into(),
);
}
arg => {
buf.emit(arg, arg_meta);
buf.emit(instruction, meta);
}
}
} else {
buf.emit(instruction, meta)
}
}
// TODO: make a version of this that doesn't miscompile `a, b = (1, 2) if True else (3, 4)`
// pub fn unpack(buf: &mut impl OptimizationBuffer) {
// let (instruction, meta) = buf.pop();
// if let Instruction::UnpackSequence { size } = instruction {
// let (arg, arg_meta) = buf.pop();
// match arg {
// Instruction::BuildTuple {
// size: tup_size,
// unpack,
// } if !unpack && tup_size == size => {
// buf.emit(
// Instruction::Reverse { amount: size },
// vec![arg_meta, meta].into(),
// );
// }
// arg => {
// buf.emit(arg, arg_meta);
// buf.emit(instruction, meta);
// }
// }
// } else {
// buf.emit(instruction, meta)
// }
// }
4 changes: 4 additions & 0 deletions tests/snippets/if_expressions.py
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Expand Up @@ -24,3 +24,7 @@ def func2():
return 20

assert ret(func1() or func2()) == 20

a, b = (1, 2) if True else (3, 4)
assert a == 1
assert b == 2