wasmtime_environ/gc/
drc.rs

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//! Layout of Wasm GC objects in the deferred reference-counting collector.

use super::*;

/// The size of the `VMDrcHeader` header for GC objects.
pub const HEADER_SIZE: u32 = 16;

/// The align of the `VMDrcHeader` header for GC objects.
pub const HEADER_ALIGN: u32 = 8;

/// The offset of the length field in a `VMDrcArrayHeader`.
pub const ARRAY_LENGTH_OFFSET: u32 = HEADER_SIZE;

/// The layout of Wasm GC objects in the deferred reference-counting collector.
#[derive(Default)]
pub struct DrcTypeLayouts;

impl GcTypeLayouts for DrcTypeLayouts {
    fn array_length_field_offset(&self) -> u32 {
        ARRAY_LENGTH_OFFSET
    }

    fn array_layout(&self, ty: &WasmArrayType) -> GcArrayLayout {
        common_array_layout(ty, HEADER_SIZE, HEADER_ALIGN, ARRAY_LENGTH_OFFSET)
    }

    fn struct_layout(&self, ty: &WasmStructType) -> GcStructLayout {
        common_struct_layout(ty, HEADER_SIZE, HEADER_ALIGN)
    }
}