cranelift_codegen/ir/
entities.rs

1//! Cranelift IR entity references.
2//!
3//! Instructions in Cranelift IR need to reference other entities in the function. This can be other
4//! parts of the function like basic blocks or stack slots, or it can be external entities
5//! that are declared in the function preamble in the text format.
6//!
7//! These entity references in instruction operands are not implemented as Rust references both
8//! because Rust's ownership and mutability rules make it difficult, and because 64-bit pointers
9//! take up a lot of space, and we want a compact in-memory representation. Instead, entity
10//! references are structs wrapping a `u32` index into a table in the `Function` main data
11//! structure. There is a separate index type for each entity type, so we don't lose type safety.
12//!
13//! The `entities` module defines public types for the entity references along with constants
14//! representing an invalid reference. We prefer to use `Option<EntityRef>` whenever possible, but
15//! unfortunately that type is twice as large as the 32-bit index type on its own. Thus, compact
16//! data structures use the `PackedOption<EntityRef>` representation, while function arguments and
17//! return values prefer the more Rust-like `Option<EntityRef>` variant.
18//!
19//! The entity references all implement the `Display` trait in a way that matches the textual IR
20//! format.
21
22use crate::entity::entity_impl;
23use core::fmt;
24use core::u32;
25#[cfg(feature = "enable-serde")]
26use serde_derive::{Deserialize, Serialize};
27
28/// An opaque reference to a [basic block](https://en.wikipedia.org/wiki/Basic_block) in a
29/// [`Function`](super::function::Function).
30///
31/// You can get a `Block` using
32/// [`FunctionBuilder::create_block`](https://docs.rs/cranelift-frontend/*/cranelift_frontend/struct.FunctionBuilder.html#method.create_block)
33///
34/// While the order is stable, it is arbitrary and does not necessarily resemble the layout order.
35#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
36#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
37pub struct Block(u32);
38entity_impl!(Block, "block");
39
40impl Block {
41    /// Create a new block reference from its number. This corresponds to the `blockNN` representation.
42    ///
43    /// This method is for use by the parser.
44    pub fn with_number(n: u32) -> Option<Self> {
45        if n < u32::MAX { Some(Self(n)) } else { None }
46    }
47}
48
49/// An opaque reference to an SSA value.
50///
51/// You can get a constant `Value` from the following
52/// [`InstBuilder`](super::InstBuilder) instructions:
53///
54/// - [`iconst`](super::InstBuilder::iconst) for integer constants
55/// - [`f16const`](super::InstBuilder::f16const) for 16-bit float constants
56/// - [`f32const`](super::InstBuilder::f32const) for 32-bit float constants
57/// - [`f64const`](super::InstBuilder::f64const) for 64-bit float constants
58/// - [`f128const`](super::InstBuilder::f128const) for 128-bit float constants
59/// - [`vconst`](super::InstBuilder::vconst) for vector constants
60///
61/// Any `InstBuilder` instruction that has an output will also return a `Value`.
62///
63/// While the order is stable, it is arbitrary.
64#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
65#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
66pub struct Value(u32);
67entity_impl!(Value, "v");
68
69impl Value {
70    /// Create a value from its number representation.
71    /// This is the number in the `vNN` notation.
72    ///
73    /// This method is for use by the parser.
74    pub fn with_number(n: u32) -> Option<Self> {
75        if n < u32::MAX / 2 {
76            Some(Self(n))
77        } else {
78            None
79        }
80    }
81}
82
83/// An opaque reference to an instruction in a [`Function`](super::Function).
84///
85/// Most usage of `Inst` is internal. `Inst`ructions are returned by
86/// [`InstBuilder`](super::InstBuilder) instructions that do not return a
87/// [`Value`], such as control flow and trap instructions, as well as instructions that return a
88/// variable (potentially zero!) number of values, like call or call-indirect instructions. To get
89/// the `Value` of such instructions, use [`inst_results`](super::DataFlowGraph::inst_results) or
90/// its analogue in `cranelift_frontend::FuncBuilder`.
91///
92/// [inst_comment]: https://github.com/bjorn3/rustc_codegen_cranelift/blob/0f8814fd6da3d436a90549d4bb19b94034f2b19c/src/pretty_clif.rs
93///
94/// While the order is stable, it is arbitrary and does not necessarily resemble the layout order.
95#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
96#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
97pub struct Inst(u32);
98entity_impl!(Inst, "inst");
99
100/// An opaque reference to a stack slot.
101///
102/// Stack slots represent an address on the
103/// [call stack](https://en.wikipedia.org/wiki/Call_stack).
104///
105/// `StackSlot`s can be created with
106/// [`FunctionBuilder::create_sized_stack_slot`](https://docs.rs/cranelift-frontend/*/cranelift_frontend/struct.FunctionBuilder.html#method.create_sized_stack_slot)
107/// or
108/// [`FunctionBuilder::create_dynamic_stack_slot`](https://docs.rs/cranelift-frontend/*/cranelift_frontend/struct.FunctionBuilder.html#method.create_dynamic_stack_slot).
109///
110/// `StackSlot`s are most often used with
111/// [`stack_addr`](super::InstBuilder::stack_addr),
112/// [`stack_load`](super::InstBuilder::stack_load), and
113/// [`stack_store`](super::InstBuilder::stack_store).
114///
115/// While the order is stable, it is arbitrary and does not necessarily resemble the stack order.
116#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
117#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
118pub struct StackSlot(u32);
119entity_impl!(StackSlot, "ss");
120
121impl StackSlot {
122    /// Create a new stack slot reference from its number.
123    ///
124    /// This method is for use by the parser.
125    pub fn with_number(n: u32) -> Option<Self> {
126        if n < u32::MAX { Some(Self(n)) } else { None }
127    }
128}
129
130/// An opaque reference to a dynamic stack slot.
131#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
132#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
133pub struct DynamicStackSlot(u32);
134entity_impl!(DynamicStackSlot, "dss");
135
136impl DynamicStackSlot {
137    /// Create a new stack slot reference from its number.
138    ///
139    /// This method is for use by the parser.
140    pub fn with_number(n: u32) -> Option<Self> {
141        if n < u32::MAX { Some(Self(n)) } else { None }
142    }
143}
144
145/// An opaque reference to a dynamic type.
146#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
147#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
148pub struct DynamicType(u32);
149entity_impl!(DynamicType, "dt");
150
151impl DynamicType {
152    /// Create a new dynamic type reference from its number.
153    ///
154    /// This method is for use by the parser.
155    pub fn with_number(n: u32) -> Option<Self> {
156        if n < u32::MAX { Some(Self(n)) } else { None }
157    }
158}
159
160/// An opaque reference to a global value.
161///
162/// A `GlobalValue` is a [`Value`] that will be live across the entire
163/// function lifetime. It can be preloaded from other global values.
164///
165/// You can create a `GlobalValue` in the following ways:
166///
167/// - When compiling to native code, you can use it for objects in static memory with
168///   [`Module::declare_data_in_func`](https://docs.rs/cranelift-module/*/cranelift_module/trait.Module.html#method.declare_data_in_func).
169/// - For any compilation target, it can be registered with
170///   [`FunctionBuilder::create_global_value`](https://docs.rs/cranelift-frontend/*/cranelift_frontend/struct.FunctionBuilder.html#method.create_global_value).
171///
172/// `GlobalValue`s can be retrieved with
173/// [`InstBuilder:global_value`](super::InstBuilder::global_value).
174///
175/// While the order is stable, it is arbitrary.
176#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
177#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
178pub struct GlobalValue(u32);
179entity_impl!(GlobalValue, "gv");
180
181impl GlobalValue {
182    /// Create a new global value reference from its number.
183    ///
184    /// This method is for use by the parser.
185    pub fn with_number(n: u32) -> Option<Self> {
186        if n < u32::MAX { Some(Self(n)) } else { None }
187    }
188}
189
190/// An opaque reference to a constant.
191///
192/// You can store [`ConstantData`](super::ConstantData) in a
193/// [`ConstantPool`](super::ConstantPool) for efficient storage and retrieval.
194/// See [`ConstantPool::insert`](super::ConstantPool::insert).
195///
196/// While the order is stable, it is arbitrary and does not necessarily resemble the order in which
197/// the constants are written in the constant pool.
198#[derive(Copy, Clone, PartialEq, Eq, Hash, Ord, PartialOrd)]
199#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
200pub struct Constant(u32);
201entity_impl!(Constant, "const");
202
203impl Constant {
204    /// Create a const reference from its number.
205    ///
206    /// This method is for use by the parser.
207    pub fn with_number(n: u32) -> Option<Self> {
208        if n < u32::MAX { Some(Self(n)) } else { None }
209    }
210}
211
212/// An opaque reference to an immediate.
213///
214/// Some immediates (e.g. SIMD shuffle masks) are too large to store in the
215/// [`InstructionData`](super::instructions::InstructionData) struct and therefore must be
216/// tracked separately in [`DataFlowGraph::immediates`](super::dfg::DataFlowGraph). `Immediate`
217/// provides a way to reference values stored there.
218///
219/// While the order is stable, it is arbitrary.
220#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
221#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
222pub struct Immediate(u32);
223entity_impl!(Immediate, "imm");
224
225impl Immediate {
226    /// Create an immediate reference from its number.
227    ///
228    /// This method is for use by the parser.
229    pub fn with_number(n: u32) -> Option<Self> {
230        if n < u32::MAX { Some(Self(n)) } else { None }
231    }
232}
233
234/// An opaque reference to a [jump table](https://en.wikipedia.org/wiki/Branch_table).
235///
236/// `JumpTable`s are used for indirect branching and are specialized for dense,
237/// 0-based jump offsets. If you want a jump table which doesn't start at 0,
238/// or is not contiguous, consider using a [`Switch`](https://docs.rs/cranelift-frontend/*/cranelift_frontend/struct.Switch.html) instead.
239///
240/// `JumpTable` are used with [`br_table`](super::InstBuilder::br_table).
241///
242/// `JumpTable`s can be created with
243/// [`create_jump_table`](https://docs.rs/cranelift-frontend/*/cranelift_frontend/struct.FunctionBuilder.html#method.create_jump_table).
244///
245/// While the order is stable, it is arbitrary.
246#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
247#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
248pub struct JumpTable(u32);
249entity_impl!(JumpTable, "jt");
250
251impl JumpTable {
252    /// Create a new jump table reference from its number.
253    ///
254    /// This method is for use by the parser.
255    pub fn with_number(n: u32) -> Option<Self> {
256        if n < u32::MAX { Some(Self(n)) } else { None }
257    }
258}
259
260/// An opaque reference to another [`Function`](super::Function).
261///
262/// `FuncRef`s are used for [direct](super::InstBuilder::call) function calls
263/// and by [`func_addr`](super::InstBuilder::func_addr) for use in
264/// [indirect](super::InstBuilder::call_indirect) function calls.
265///
266/// `FuncRef`s can be created with
267///
268/// - [`FunctionBuilder::import_function`](https://docs.rs/cranelift-frontend/*/cranelift_frontend/struct.FunctionBuilder.html#method.import_function)
269///   for external functions
270/// - [`Module::declare_func_in_func`](https://docs.rs/cranelift-module/*/cranelift_module/trait.Module.html#method.declare_func_in_func)
271///   for functions declared elsewhere in the same native
272///   [`Module`](https://docs.rs/cranelift-module/*/cranelift_module/trait.Module.html)
273///
274/// While the order is stable, it is arbitrary.
275#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
276#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
277pub struct FuncRef(u32);
278entity_impl!(FuncRef, "fn");
279
280impl FuncRef {
281    /// Create a new external function reference from its number.
282    ///
283    /// This method is for use by the parser.
284    pub fn with_number(n: u32) -> Option<Self> {
285        if n < u32::MAX { Some(Self(n)) } else { None }
286    }
287}
288
289/// A reference to an `UserExternalName`, declared with `Function::declare_imported_user_function`.
290#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Default)]
291#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
292pub struct UserExternalNameRef(u32);
293entity_impl!(UserExternalNameRef, "userextname");
294
295/// An opaque reference to a function [`Signature`](super::Signature).
296///
297/// `SigRef`s are used to declare a function with
298/// [`FunctionBuilder::import_function`](https://docs.rs/cranelift-frontend/*/cranelift_frontend/struct.FunctionBuilder.html#method.import_function)
299/// as well as to make an [indirect function call](super::InstBuilder::call_indirect).
300///
301/// `SigRef`s can be created with
302/// [`FunctionBuilder::import_signature`](https://docs.rs/cranelift-frontend/*/cranelift_frontend/struct.FunctionBuilder.html#method.import_signature).
303///
304/// You can retrieve the [`Signature`](super::Signature) that was used to create a `SigRef` with
305/// [`FunctionBuilder::signature`](https://docs.rs/cranelift-frontend/*/cranelift_frontend/struct.FunctionBuilder.html#method.signature) or
306/// [`func.dfg.signatures`](super::dfg::DataFlowGraph::signatures).
307///
308/// While the order is stable, it is arbitrary.
309#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
310#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
311pub struct SigRef(u32);
312entity_impl!(SigRef, "sig");
313
314impl SigRef {
315    /// Create a new function signature reference from its number.
316    ///
317    /// This method is for use by the parser.
318    pub fn with_number(n: u32) -> Option<Self> {
319        if n < u32::MAX { Some(Self(n)) } else { None }
320    }
321}
322
323/// An opaque exception tag.
324///
325/// Exception tags are used to denote the identity of an exception for
326/// matching by catch-handlers in exception tables.
327///
328/// The index space is arbitrary and is given meaning only by the
329/// embedder of Cranelift. Cranelift will carry through these tags
330/// from exception tables to the handler metadata produced as output
331/// (for use by the embedder's unwinder).
332#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
333#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
334pub struct ExceptionTag(u32);
335entity_impl!(ExceptionTag, "tag");
336
337impl ExceptionTag {
338    /// Create a new exception tag from its arbitrary index.
339    ///
340    /// This method is for use by the parser.
341    pub fn with_number(n: u32) -> Option<Self> {
342        if n < u32::MAX { Some(Self(n)) } else { None }
343    }
344}
345
346/// An opaque reference to an exception table.
347///
348/// `ExceptionTable`s are used for describing exception catch handlers on
349/// `try_call` and `try_call_indirect` instructions.
350#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
351#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
352pub struct ExceptionTable(u32);
353entity_impl!(ExceptionTable, "extable");
354
355impl ExceptionTable {
356    /// Create a new exception table reference from its number.
357    ///
358    /// This method is for use by the parser.
359    pub fn with_number(n: u32) -> Option<Self> {
360        if n < u32::MAX { Some(Self(n)) } else { None }
361    }
362}
363
364/// An opaque reference to any of the entities defined in this module that can appear in CLIF IR.
365#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
366#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
367pub enum AnyEntity {
368    /// The whole function.
369    Function,
370    /// a basic block.
371    Block(Block),
372    /// An instruction.
373    Inst(Inst),
374    /// An SSA value.
375    Value(Value),
376    /// A stack slot.
377    StackSlot(StackSlot),
378    /// A dynamic stack slot.
379    DynamicStackSlot(DynamicStackSlot),
380    /// A dynamic type
381    DynamicType(DynamicType),
382    /// A Global value.
383    GlobalValue(GlobalValue),
384    /// A jump table.
385    JumpTable(JumpTable),
386    /// A constant.
387    Constant(Constant),
388    /// An external function.
389    FuncRef(FuncRef),
390    /// A function call signature.
391    SigRef(SigRef),
392    /// An exception table.
393    ExceptionTable(ExceptionTable),
394    /// A function's stack limit
395    StackLimit,
396}
397
398impl fmt::Display for AnyEntity {
399    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
400        match *self {
401            Self::Function => write!(f, "function"),
402            Self::Block(r) => r.fmt(f),
403            Self::Inst(r) => r.fmt(f),
404            Self::Value(r) => r.fmt(f),
405            Self::StackSlot(r) => r.fmt(f),
406            Self::DynamicStackSlot(r) => r.fmt(f),
407            Self::DynamicType(r) => r.fmt(f),
408            Self::GlobalValue(r) => r.fmt(f),
409            Self::JumpTable(r) => r.fmt(f),
410            Self::Constant(r) => r.fmt(f),
411            Self::FuncRef(r) => r.fmt(f),
412            Self::SigRef(r) => r.fmt(f),
413            Self::ExceptionTable(r) => r.fmt(f),
414            Self::StackLimit => write!(f, "stack_limit"),
415        }
416    }
417}
418
419impl fmt::Debug for AnyEntity {
420    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
421        (self as &dyn fmt::Display).fmt(f)
422    }
423}
424
425impl From<Block> for AnyEntity {
426    fn from(r: Block) -> Self {
427        Self::Block(r)
428    }
429}
430
431impl From<Inst> for AnyEntity {
432    fn from(r: Inst) -> Self {
433        Self::Inst(r)
434    }
435}
436
437impl From<Value> for AnyEntity {
438    fn from(r: Value) -> Self {
439        Self::Value(r)
440    }
441}
442
443impl From<StackSlot> for AnyEntity {
444    fn from(r: StackSlot) -> Self {
445        Self::StackSlot(r)
446    }
447}
448
449impl From<DynamicStackSlot> for AnyEntity {
450    fn from(r: DynamicStackSlot) -> Self {
451        Self::DynamicStackSlot(r)
452    }
453}
454
455impl From<DynamicType> for AnyEntity {
456    fn from(r: DynamicType) -> Self {
457        Self::DynamicType(r)
458    }
459}
460
461impl From<GlobalValue> for AnyEntity {
462    fn from(r: GlobalValue) -> Self {
463        Self::GlobalValue(r)
464    }
465}
466
467impl From<JumpTable> for AnyEntity {
468    fn from(r: JumpTable) -> Self {
469        Self::JumpTable(r)
470    }
471}
472
473impl From<Constant> for AnyEntity {
474    fn from(r: Constant) -> Self {
475        Self::Constant(r)
476    }
477}
478
479impl From<FuncRef> for AnyEntity {
480    fn from(r: FuncRef) -> Self {
481        Self::FuncRef(r)
482    }
483}
484
485impl From<SigRef> for AnyEntity {
486    fn from(r: SigRef) -> Self {
487        Self::SigRef(r)
488    }
489}
490
491impl From<ExceptionTable> for AnyEntity {
492    fn from(r: ExceptionTable) -> Self {
493        Self::ExceptionTable(r)
494    }
495}
496
497#[cfg(test)]
498mod tests {
499    use super::*;
500    use alloc::string::ToString;
501
502    #[test]
503    fn value_with_number() {
504        assert_eq!(Value::with_number(0).unwrap().to_string(), "v0");
505        assert_eq!(Value::with_number(1).unwrap().to_string(), "v1");
506
507        assert_eq!(Value::with_number(u32::MAX / 2), None);
508        assert!(Value::with_number(u32::MAX / 2 - 1).is_some());
509    }
510
511    #[test]
512    fn memory() {
513        use crate::packed_option::PackedOption;
514        use core::mem;
515        // This is the whole point of `PackedOption`.
516        assert_eq!(
517            mem::size_of::<Value>(),
518            mem::size_of::<PackedOption<Value>>()
519        );
520    }
521
522    #[test]
523    fn memory_option() {
524        use core::mem;
525        // PackedOption is used because Option<EntityRef> is twice as large
526        // as EntityRef. If this ever fails to be the case, this test will fail.
527        assert_eq!(mem::size_of::<Value>() * 2, mem::size_of::<Option<Value>>());
528    }
529
530    #[test]
531    fn constant_with_number() {
532        assert_eq!(Constant::with_number(0).unwrap().to_string(), "const0");
533        assert_eq!(Constant::with_number(1).unwrap().to_string(), "const1");
534    }
535}
cranelift_codegen/ir/entities.rs

cranelift_codegen/ir/
entities.rs
