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feat(ssa): Simplify signed casts #6166

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Merged
vezenovm merged 1 commit into from
Sep 27, 2024
Merged

feat(ssa): Simplify signed casts #6166

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22 changes: 20 additions & 2 deletions compiler/noirc_evaluator/src/ssa/ir/instruction/cast.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -27,10 +27,10 @@ pub(super) fn simplify_cast(
SimplifiedTo(value)
}
(
Type::Numeric(NumericType::Unsigned { .. }),
Type::Numeric(NumericType::Unsigned { .. } | NumericType::Signed { .. }),
Type::Numeric(NumericType::NativeField),
) => {
// Unsigned -> Field: redefine same constant as Field
// Unsigned/Signed -> Field: redefine same constant as Field
SimplifiedTo(dfg.make_constant(constant, dst_typ.clone()))
}
(
Expand All @@ -48,6 +48,24 @@ pub(super) fn simplify_cast(
let truncated = FieldElement::from_be_bytes_reduce(&truncated.to_bytes_be());
SimplifiedTo(dfg.make_constant(truncated, dst_typ.clone()))
}
(
Type::Numeric(
NumericType::NativeField
| NumericType::Unsigned { .. }
| NumericType::Signed { .. },
),
Type::Numeric(NumericType::Signed { bit_size }),
) => {
// Field/Unsigned -> signed
// We only simplify to signed when we are below the maximum signed integer of the destination type.
let integer_modulus = BigUint::from(2u128).pow(*bit_size - 1);
let constant_uint: BigUint = BigUint::from_bytes_be(&constant.to_be_bytes());
if constant_uint < integer_modulus {
SimplifiedTo(dfg.make_constant(constant, dst_typ.clone()))
} else {
None
}
}
_ => None,
}
} else if *dst_typ == dfg.type_of_value(value) {
Expand Down