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Walk the input list during List.find alias analysis

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ayazhafiz 2021-11-08 22:00:03 -05:00
parent 074c2ca398
commit 9e50580715
1 changed files with 24 additions and 23 deletions
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47
compiler/mono/src/alias_analysis.rs
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@ -1096,36 +1096,37 @@ fn call_spec(
ListFindUnsafe { xs } => {
let list = env.symbols[xs];
// Mark the list as being used by the "find" predicate function.
// It may be the case that all elements in the list are used by the predicate.
// Since `bag_get` assumes items are picked non-deterministically, this is
// (probably?) enough to express that usage.
let bag = builder.add_get_tuple_field(block, list, LIST_BAG_INDEX)?;
let element = builder.add_bag_get(block, bag)?;
let _bool = call_function!(builder, block, [element]);
// ListFindUnsafe returns { value: v, found: Bool=Int1 }
let output_layouts = vec![arg_layouts[0], Layout::Builtin(Builtin::Int1)];
let output_layout = Layout::Struct(&output_layouts);
let output_type = layout_spec(builder, &output_layout)?;
// We may or may not use the element we got from the list in the output struct,
// depending on whether we found the element to satisfy the "find" predicate.
let found_branch = builder.add_block();
let output_with_element =
builder.add_unknown_with(found_branch, &[element], output_type)?;
let loop_body = |builder: &mut FuncDefBuilder, block, output| {
let bag = builder.add_get_tuple_field(block, list, LIST_BAG_INDEX)?;
let element = builder.add_bag_get(block, bag)?;
let _is_found = call_function!(builder, block, [element]);
let not_found_branch = builder.add_block();
let output_without_element =
builder.add_unknown_with(not_found_branch, &[], output_type)?;
// We may or may not use the element we got from the list in the output struct,
// depending on whether we found the element to satisfy the "find" predicate.
// If we did find the element, our output "changes" to be a record including that element.
let found_branch = builder.add_block();
let new_output =
builder.add_unknown_with(block, &[element], output_type)?;
builder.add_choice(
block,
&[
BlockExpr(found_branch, output_with_element),
BlockExpr(not_found_branch, output_without_element),
],
)
let not_found_branch = builder.add_block();
builder.add_choice(
block,
&[
BlockExpr(found_branch, new_output),
BlockExpr(not_found_branch, output),
],
)
};
// Assume the output is initially { found: False, value: \empty }
let output_state = builder.add_unknown_with(block, &[], output_type)?;
add_loop(builder, block, output_type, output_state, loop_body)
}
}
}