polydat_core/compile/
marshal.rs

1// Copyright 2024-2026 Jonathan Shook
2// SPDX-License-Identifier: Apache-2.0
3
4//! Marshalling between typed `Value`s and compiled-tier slots. One
5//! place owns the rule for every port type, so embedded cones and
6//! whole compiled kernels decode alike:
7//!
8//! - scalars ride as their slot bits, one slot or two;
9//! - every `Ref2` kind rides as a `(ptr, len)` pair (jit_boundary.md,
10//!   axioms S1–S10): a typed vector, a string, or a byte string as a
11//!   slice of its elements, and a JSON, extension, or handle value as
12//!   a one-element slice holding the `Value`.
13//!
14//! Entering the compiled tier, a `Value` is borrowed: the pair points
15//! into the value the caller holds for the duration of the call.
16//! Leaving it, the pair is copied out to an owned `Value`: the
17//! interpreter and the host never hold a reference into a state's
18//! buffers.
19
20use crate::ast::SlotShape;
21use crate::ast::{PortType, Value};
22
23/// The `(ptr, len)` pair a `Ref2`-kind value is borrowed as: into the
24/// value's own bytes or element storage, or the value itself for a
25/// JSON, extension, or handle value. The pair is valid while `v` is.
26/// `None` for a scalar or for a variant the port type does not admit.
27pub(crate) fn borrow_pair(v: &Value) -> Option<(u64, u64)> {
28    Some(match v {
29        Value::Str(s) => (s.as_ptr() as usize as u64, s.len() as u64),
30        Value::Bytes(b) => (b.as_ptr() as usize as u64, b.len() as u64),
31        Value::Json(_) | Value::Ext(_) | Value::Handle(_) => (v as *const Value as usize as u64, 1),
32        Value::VecF32(v) => slice_pair(v.as_slice()),
33        Value::VecF64(v) => slice_pair(v.as_slice()),
34        Value::VecF16(v) => slice_pair(v.as_slice()),
35        Value::VecI8(v) => slice_pair(v.as_slice()),
36        Value::VecI16(v) => slice_pair(v.as_slice()),
37        Value::VecI32(v) => slice_pair(v.as_slice()),
38        Value::VecI64(v) => slice_pair(v.as_slice()),
39        _ => return None,
40    })
41}
42
43/// The `(ptr, len)` pair of a slice.
44#[inline]
45pub(crate) fn slice_pair<T>(s: &[T]) -> (u64, u64) {
46    (s.as_ptr() as usize as u64, s.len() as u64)
47}
48
49/// An empty pair for an unset `Ref2` slot: a dangling, non-null
50/// pointer with length zero, which every slice reader accepts.
51#[inline]
52pub(crate) fn empty_pair() -> (u64, u64) {
53    (
54        std::ptr::NonNull::<u8>::dangling().as_ptr() as usize as u64,
55        0,
56    )
57}
58
59/// A `Value` as the slot bits its port type rides as: the bits of a
60/// scalar, or the borrowed pair of a `Ref2` kind. `None` when the
61/// value's variant has no compiled representation.
62#[cfg(feature = "jit")]
63pub(crate) fn encode_slots(v: &Value, out: &mut [u64]) -> Option<()> {
64    match v {
65        Value::U64(x) => out[0] = *x,
66        Value::I64(x) => out[0] = *x as u64,
67        Value::F64(x) => out[0] = x.to_bits(),
68        Value::Bool(b) => out[0] = *b as u64,
69        _ => {
70            let (p, l) = borrow_pair(v)?;
71            out[0] = p;
72            out[1] = l;
73        }
74    }
75    Some(())
76}
77
78/// The value a `Ref2` pair names, copied out as the `Value` its port
79/// type declares. Every read that leaves the compiled tier goes
80/// through here.
81///
82/// # Safety
83///
84/// The pair was published by a producer whose storage is alive: its
85/// own scratch, an extern's stored value, an interned constant, or a
86/// boundary value alive for the call (axioms S3, S4).
87pub(crate) unsafe fn decode_pair(ty: PortType, ptr: u64, len: u64) -> Value {
88    use crate::ast::SliceArc;
89    let (p, n) = (ptr as usize, len as usize);
90    // SAFETY: as documented on the function.
91    unsafe {
92        match ty {
93            PortType::Str => Value::Str(std::sync::Arc::from(std::str::from_utf8_unchecked(
94                std::slice::from_raw_parts(p as *const u8, n),
95            ))),
96            PortType::Bytes => Value::Bytes(std::sync::Arc::from(std::slice::from_raw_parts(
97                p as *const u8,
98                n,
99            ))),
100            PortType::Json | PortType::Ext | PortType::Handle => {
101                if n == 0 {
102                    Value::None
103                } else {
104                    (*(p as *const Value)).clone()
105                }
106            }
107            PortType::VecF32 => Value::VecF32(SliceArc::from_vec(
108                std::slice::from_raw_parts(p as *const f32, n).to_vec(),
109            )),
110            PortType::VecF64 => Value::VecF64(SliceArc::from_vec(
111                std::slice::from_raw_parts(p as *const f64, n).to_vec(),
112            )),
113            PortType::VecF16 => Value::VecF16(SliceArc::from_vec(
114                std::slice::from_raw_parts(p as *const half::f16, n).to_vec(),
115            )),
116            PortType::VecI8 => Value::VecI8(SliceArc::from_vec(
117                std::slice::from_raw_parts(p as *const i8, n).to_vec(),
118            )),
119            PortType::VecI16 => Value::VecI16(SliceArc::from_vec(
120                std::slice::from_raw_parts(p as *const i16, n).to_vec(),
121            )),
122            PortType::VecI32 => Value::VecI32(SliceArc::from_vec(
123                std::slice::from_raw_parts(p as *const i32, n).to_vec(),
124            )),
125            PortType::VecI64 => Value::VecI64(SliceArc::from_vec(
126                std::slice::from_raw_parts(p as *const i64, n).to_vec(),
127            )),
128            other => panic!("{other:?} is not a Ref2-colored port type"),
129        }
130    }
131}
132
133/// Slot bits as the `Value` their declared port type names, copied
134/// out where they are a pair.
135pub(crate) fn decode_slot(slots: &[u64], ty: PortType) -> Value {
136    match ty {
137        PortType::F64 => Value::F64(f64::from_bits(slots[0])),
138        PortType::Bool => Value::Bool(slots[0] != 0),
139        PortType::I64 => Value::I64(slots[0] as i64),
140        // A signed narrow carrier rides sign-extended (alignment §8.1)
141        // and is the `I64` value its `Wire` impl injects.
142        PortType::I8 | PortType::I16 | PortType::I32 => Value::I64(slots[0] as i64),
143        // SAFETY: the pair in a kernel's buffer was published by a
144        // producer whose storage is alive (axioms S3, S4).
145        ty if ty.slot_color() == crate::ast::SlotColor::Ref2 => unsafe {
146            decode_pair(ty, slots[0], slots[1])
147        },
148        _ => Value::U64(slots[0]),
149    }
150}
151
152/// An output at `slot` of `buffer` as the `Value` its port type names:
153/// `decode_slot` for a one-slot carrier and a `Ref2` pair, and the
154/// two-limb reassembly for a 128-bit integer or a register word, which
155/// ride two consecutive slots (alignment §8.4 layer 1). This is the
156/// typed read every compiled kernel's `get_value` makes.
157pub fn decode_output(buffer: &[u64], slot: usize, ty: PortType) -> Value {
158    use crate::ast::{Bits128, RegLanes, SlotColor};
159    if ty.slot_color() == SlotColor::Imm2 {
160        let limbs = Bits128([buffer[slot], buffer[slot + 1]]);
161        return match ty {
162            PortType::U128 => Value::U128(limbs),
163            PortType::I128 => Value::I128(limbs),
164            PortType::RegI8x16 => Value::Reg128(limbs, RegLanes::I8x16),
165            PortType::RegI16x8 => Value::Reg128(limbs, RegLanes::I16x8),
166            PortType::RegI32x4 => Value::Reg128(limbs, RegLanes::I32x4),
167            PortType::RegI64x2 => Value::Reg128(limbs, RegLanes::I64x2),
168            PortType::RegF16x8 => Value::Reg128(limbs, RegLanes::F16x8),
169            PortType::RegF32x4 => Value::Reg128(limbs, RegLanes::F32x4),
170            PortType::RegF64x2 => Value::Reg128(limbs, RegLanes::F64x2),
171            _ => Value::Reg128(limbs, RegLanes::Raw),
172        };
173    }
174    decode_slot(&buffer[slot..], ty)
175}
176
177/// An argument's slots as a borrowed view of the value, decoded by its
178/// port type: nothing is copied. A string, byte string, or value is
179/// borrowed through its pair, valid while its producer's storage is.
180///
181/// # Safety
182///
183/// As for `decode_pair`.
184pub unsafe fn arg_ref<'a>(ty: PortType, slots: &'a [u64]) -> crate::ast::ValueRef<'a> {
185    use crate::ast::ValueRef;
186    let (p, n) = (
187        slots.first().copied().unwrap_or(0) as usize,
188        slots.get(1).copied().unwrap_or(0) as usize,
189    );
190    // SAFETY: as documented on the function.
191    unsafe {
192        match ty {
193            PortType::U64 => ValueRef::U64(slots[0]),
194            PortType::I64 | PortType::I8 | PortType::I16 | PortType::I32 => {
195                ValueRef::I64(slots[0] as i64)
196            }
197            PortType::F64 => ValueRef::F64(f64::from_bits(slots[0])),
198            PortType::Bool => ValueRef::Bool(slots[0] != 0),
199            PortType::Str => ValueRef::Str(std::str::from_utf8_unchecked(
200                std::slice::from_raw_parts(p as *const u8, n),
201            )),
202            PortType::Bytes => ValueRef::Bytes(std::slice::from_raw_parts(p as *const u8, n)),
203            PortType::Json | PortType::Ext | PortType::Handle => {
204                if n == 0 {
205                    ValueRef::None
206                } else {
207                    ValueRef::from(&*(p as *const Value))
208                }
209            }
210            _ => ValueRef::U64(slots[0]),
211        }
212    }
213}
polydat_core/compile/marshal.rs

polydat_core/compile/
marshal.rs
