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fix(codegen): ILP32 class-field access must use target-aware object-header size #6107

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Merged
proggeramlug merged 1 commit into from
Jul 8, 2026
Merged

fix(codegen): ILP32 class-field access must use target-aware object-header size #6107

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14 changes: 12 additions & 2 deletions crates/perry-codegen/src/expr/property_get.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1325,10 +1325,20 @@ pub(crate) fn lower(ctx: &mut FnCtx<'_>, expr: &Expr) -> Result<String> {
.cond_br(&guard_pass, &fast_label, &fallback_label);

ctx.current_block = fast_idx;
// arm64_32 watchOS: the object fields region begins at
// `size_of::<ObjectHeader>()` past the user pointer — 24 on
// 64-bit, 20 on ILP32 (the trailing `keys_array` pointer is 4
// bytes there). A hardcoded 24 reads every class field 4 bytes
// off on a 32-bit watch, so this inline class-field load
// disagreed with the generic-PIC load / runtime setter (both
// target-aware) and typed-object string fields came back as
// word-swapped NaN-boxes. Derive it from the target triple
// (no-op on 64-bit; see `target_layout`).
let header_skip =
crate::target_layout::object_header_size_bytes(ctx.target_triple)
.to_string();
let blk = ctx.block();
let obj_ptr = blk.inttoptr(I64, &obj_handle);
// Skip the 24-byte ObjectHeader.
let header_skip = "24".to_string();
let fields_base = blk.gep(I8, &obj_ptr, &[(I64, &header_skip)]);
let field_ptr = blk.gep(DOUBLE, &fields_base, &[(I64, &field_idx_str)]);
let val_fast = blk.load(DOUBLE, &field_ptr);
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12 changes: 11 additions & 1 deletion crates/perry-codegen/src/expr/property_set.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -650,9 +650,19 @@ pub(crate) fn lower(ctx: &mut FnCtx<'_>, expr: &Expr) -> Result<String> {
let field_set_barrier_needed =
!expr_produces_non_pointer_bits_by_construction(ctx, value);
let raw_stored_value = {
// arm64_32 watchOS: the object fields region begins at
// `size_of::<ObjectHeader>()` past the user pointer — 24 on
// 64-bit, 20 on ILP32 (the trailing `keys_array` pointer is
// 4 bytes there). A hardcoded 24 writes every class field 4
// bytes off on a 32-bit watch; the paired inline read
// (`property_get`) and the runtime setter must agree, so
// derive it from the target triple (no-op on 64-bit; see
// `target_layout`).
let header_skip =
crate::target_layout::object_header_size_bytes(ctx.target_triple)
.to_string();
let blk = ctx.block();
let obj_ptr = blk.inttoptr(I64, &obj_handle);
let header_skip = "24".to_string();
let fields_base = blk.gep(I8, &obj_ptr, &[(I64, &header_skip)]);
let field_ptr = blk.gep(DOUBLE, &fields_base, &[(I64, &field_idx_str)]);
let raw_stored_value = if requires_raw_f64 {
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