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fix(pointer-casts): support array-to-wrapper projections #1014

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fix(pointer-casts): support array-to-wrapper projections #1014

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77d87b8
fix(pointer-casts): support array-to-wrapper projections
Stevengre Apr 3, 2026
f789dd5
fix(pointer-casts): preserve wrapper projections for iterators
Stevengre Apr 3, 2026
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14 changes: 14 additions & 0 deletions kmir/src/kmir/kdist/mir-semantics/rt/data.md
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Original file line number Diff line number Diff line change
Expand Up @@ -492,6 +492,20 @@ The situation typically arises when the stored value is a pointer (`NonNull`) bu
)
=> #traverseProjection(DEST, Aggregate(variantIdx(0), ListItem(VALUE)), PROJS, CtxWrapStruct CTXTS) ... </k>
[preserves-definedness, priority(100)]

rule <k> #traverseProjection(
DEST,
Aggregate(variantIdx(0), ListItem(Range(ELEMS))),
projectionElemConstantIndex(I, MIN_LENGTH, FROM_END) PROJS,
CTXTS
)
=> #traverseProjection(
DEST,
Range(ELEMS),
projectionElemConstantIndex(I, MIN_LENGTH, FROM_END) PROJS,
CTXTS
) ... </k>
[preserves-definedness, priority(100)]
```

A somewhat dual case to this rule can occur when a pointer into an array of data elements has been offset and is then dereferenced.
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25 changes: 18 additions & 7 deletions kmir/src/kmir/kdist/mir-semantics/rt/types.md
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Original file line number Diff line number Diff line change
Expand Up @@ -113,14 +113,11 @@ the source should be wrapped rather than unwrapped (e.g., `*const [u8;2] → *co
)
requires #zeroFieldOffset(LAYOUT)

rule #pointeeProjection(SRC:TypeInfo, typeInfoStructType(_NAME, _ADTDEF, FIELD .Tys, LAYOUT))
=> maybeConcatProj(
projectionElemWrapStruct,
#pointeeProjection(SRC, lookupTy(FIELD))
)
rule #pointeeProjection(SRC:TypeInfo, TGT)
=> #pointeeProjectionTarget(SRC, TGT)
requires #isArrayType(SRC)
andBool #zeroFieldOffset(LAYOUT)
andBool lookupTy(FIELD) ==K SRC
andBool #wholeArrayTargetCompatible(SRC, TGT)
andBool SRC =/=K TGT
[priority(42)]

rule #pointeeProjection(typeInfoArrayType(TY1, _), TY2)
Expand Down Expand Up @@ -189,6 +186,20 @@ the source-first strategy.
rule #layoutOffsets(someLayoutShape(layoutShape(fieldsShapeArbitrary(mk(OFFSETS)), _, _, _, _))) => OFFSETS
rule #layoutOffsets(noLayoutShape) => .MachineSizes
rule #layoutOffsets(_) => .MachineSizes [owise]

syntax Bool ::= #wholeArrayTargetCompatible ( TypeInfo , TypeInfo ) [function, total]
// ----------------------------------------------------------------------------
rule #wholeArrayTargetCompatible(SRC, SRC) => true

rule #wholeArrayTargetCompatible(SRC, typeInfoStructType(_, _, FIELD .Tys, LAYOUT))
=> #wholeArrayTargetCompatible(SRC, lookupTy(FIELD))
requires #zeroFieldOffset(LAYOUT)

rule #wholeArrayTargetCompatible(SRC, typeInfoArrayType(ELEM_TY, someTyConst(tyConst(KIND, _))))
=> #wholeArrayTargetCompatible(SRC, lookupTy(ELEM_TY))
requires readTyConstInt(KIND) ==Int 1

rule #wholeArrayTargetCompatible(_, _) => false [owise]
```

--------------------------------------------------
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