1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use graphviz::IntoCow;
12 use middle::const_val::ConstVal;
13 use rustc_const_math::{ConstUsize, ConstInt, ConstMathErr};
14 use rustc_data_structures::indexed_vec::{IndexVec, Idx};
15 use rustc_data_structures::control_flow_graph::dominators::{Dominators, dominators};
16 use rustc_data_structures::control_flow_graph::{GraphPredecessors, GraphSuccessors};
17 use rustc_data_structures::control_flow_graph::ControlFlowGraph;
18 use hir::def::CtorKind;
19 use hir::def_id::DefId;
20 use ty::subst::Substs;
21 use ty::{self, AdtDef, ClosureSubsts, Region, Ty};
23 use rustc_back::slice;
26 use std::borrow::{Cow};
28 use std::fmt::{self, Debug, Formatter, Write};
30 use std::ops::{Index, IndexMut};
31 use std::vec::IntoIter;
32 use syntax::ast::Name;
41 macro_rules! newtype_index {
42 ($name:ident, $debug_name:expr) => (
43 #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord,
44 RustcEncodable, RustcDecodable)]
45 pub struct $name(u32);
48 fn new(value: usize) -> Self {
49 assert!(value < (u32::MAX) as usize);
52 fn index(self) -> usize {
57 impl Debug for $name {
58 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
59 write!(fmt, "{}{}", $debug_name, self.0)
65 /// Lowered representation of a single function.
66 // Do not implement clone for Mir, its easy to do so accidently and its kind of expensive.
67 #[derive(RustcEncodable, RustcDecodable, Debug)]
68 pub struct Mir<'tcx> {
69 /// List of basic blocks. References to basic block use a newtyped index type `BasicBlock`
70 /// that indexes into this vector.
71 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
73 /// List of visibility (lexical) scopes; these are referenced by statements
74 /// and used (eventually) for debuginfo. Indexed by a `VisibilityScope`.
75 pub visibility_scopes: IndexVec<VisibilityScope, VisibilityScopeData>,
77 /// Rvalues promoted from this function, such as borrows of constants.
78 /// Each of them is the Mir of a constant with the fn's type parameters
79 /// in scope, but a separate set of locals.
80 pub promoted: IndexVec<Promoted, Mir<'tcx>>,
82 /// Return type of the function.
83 pub return_ty: Ty<'tcx>,
85 /// Declarations of locals.
87 /// The first local is the return value pointer, followed by `arg_count`
88 /// locals for the function arguments, followed by any user-declared
89 /// variables and temporaries.
90 pub local_decls: IndexVec<Local, LocalDecl<'tcx>>,
92 /// Number of arguments this function takes.
94 /// Starting at local 1, `arg_count` locals will be provided by the caller
95 /// and can be assumed to be initialized.
97 /// If this MIR was built for a constant, this will be 0.
100 /// Names and capture modes of all the closure upvars, assuming
101 /// the first argument is either the closure or a reference to it.
102 pub upvar_decls: Vec<UpvarDecl>,
104 /// Mark an argument local (which must be a tuple) as getting passed as
105 /// its individual components at the LLVM level.
107 /// This is used for the "rust-call" ABI.
108 pub spread_arg: Option<Local>,
110 /// A span representing this MIR, for error reporting
113 /// A cache for various calculations
117 /// where execution begins
118 pub const START_BLOCK: BasicBlock = BasicBlock(0);
120 impl<'tcx> Mir<'tcx> {
121 pub fn new(basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
122 visibility_scopes: IndexVec<VisibilityScope, VisibilityScopeData>,
123 promoted: IndexVec<Promoted, Mir<'tcx>>,
125 local_decls: IndexVec<Local, LocalDecl<'tcx>>,
127 upvar_decls: Vec<UpvarDecl>,
130 // We need `arg_count` locals, and one for the return pointer
131 assert!(local_decls.len() >= arg_count + 1,
132 "expected at least {} locals, got {}", arg_count + 1, local_decls.len());
133 assert_eq!(local_decls[RETURN_POINTER].ty, return_ty);
136 basic_blocks: basic_blocks,
137 visibility_scopes: visibility_scopes,
139 return_ty: return_ty,
140 local_decls: local_decls,
141 arg_count: arg_count,
142 upvar_decls: upvar_decls,
145 cache: cache::Cache::new()
150 pub fn basic_blocks(&self) -> &IndexVec<BasicBlock, BasicBlockData<'tcx>> {
155 pub fn basic_blocks_mut(&mut self) -> &mut IndexVec<BasicBlock, BasicBlockData<'tcx>> {
156 self.cache.invalidate();
157 &mut self.basic_blocks
161 pub fn predecessors(&self) -> Ref<IndexVec<BasicBlock, Vec<BasicBlock>>> {
162 self.cache.predecessors(self)
166 pub fn predecessors_for(&self, bb: BasicBlock) -> Ref<Vec<BasicBlock>> {
167 Ref::map(self.predecessors(), |p| &p[bb])
171 pub fn dominators(&self) -> Dominators<BasicBlock> {
176 pub fn local_kind(&self, local: Local) -> LocalKind {
177 let index = local.0 as usize;
179 debug_assert!(self.local_decls[local].mutability == Mutability::Mut,
180 "return pointer should be mutable");
182 LocalKind::ReturnPointer
183 } else if index < self.arg_count + 1 {
185 } else if self.local_decls[local].name.is_some() {
188 debug_assert!(self.local_decls[local].mutability == Mutability::Mut,
189 "temp should be mutable");
195 /// Returns an iterator over all temporaries.
197 pub fn temps_iter<'a>(&'a self) -> impl Iterator<Item=Local> + 'a {
198 (self.arg_count+1..self.local_decls.len()).filter_map(move |index| {
199 let local = Local::new(index);
200 if self.local_decls[local].source_info.is_none() {
208 /// Returns an iterator over all user-declared locals.
210 pub fn vars_iter<'a>(&'a self) -> impl Iterator<Item=Local> + 'a {
211 (self.arg_count+1..self.local_decls.len()).filter_map(move |index| {
212 let local = Local::new(index);
213 if self.local_decls[local].source_info.is_none() {
221 /// Returns an iterator over all function arguments.
223 pub fn args_iter(&self) -> impl Iterator<Item=Local> {
224 let arg_count = self.arg_count;
225 (1..arg_count+1).map(Local::new)
228 /// Returns an iterator over all user-defined variables and compiler-generated temporaries (all
229 /// locals that are neither arguments nor the return pointer).
231 pub fn vars_and_temps_iter(&self) -> impl Iterator<Item=Local> {
232 let arg_count = self.arg_count;
233 let local_count = self.local_decls.len();
234 (arg_count+1..local_count).map(Local::new)
237 /// Changes a statement to a nop. This is both faster than deleting instructions and avoids
238 /// invalidating statement indices in `Location`s.
239 pub fn make_statement_nop(&mut self, location: Location) {
240 let block = &mut self[location.block];
241 debug_assert!(location.statement_index < block.statements.len());
242 block.statements[location.statement_index].make_nop()
246 impl<'tcx> Index<BasicBlock> for Mir<'tcx> {
247 type Output = BasicBlockData<'tcx>;
250 fn index(&self, index: BasicBlock) -> &BasicBlockData<'tcx> {
251 &self.basic_blocks()[index]
255 impl<'tcx> IndexMut<BasicBlock> for Mir<'tcx> {
257 fn index_mut(&mut self, index: BasicBlock) -> &mut BasicBlockData<'tcx> {
258 &mut self.basic_blocks_mut()[index]
262 /// Grouped information about the source code origin of a MIR entity.
263 /// Intended to be inspected by diagnostics and debuginfo.
264 /// Most passes can work with it as a whole, within a single function.
265 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
266 pub struct SourceInfo {
267 /// Source span for the AST pertaining to this MIR entity.
270 /// The lexical visibility scope, i.e. which bindings can be seen.
271 pub scope: VisibilityScope
274 ///////////////////////////////////////////////////////////////////////////
275 // Mutability and borrow kinds
277 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
278 pub enum Mutability {
283 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
284 pub enum BorrowKind {
285 /// Data must be immutable and is aliasable.
288 /// Data must be immutable but not aliasable. This kind of borrow
289 /// cannot currently be expressed by the user and is used only in
290 /// implicit closure bindings. It is needed when you the closure
291 /// is borrowing or mutating a mutable referent, e.g.:
293 /// let x: &mut isize = ...;
294 /// let y = || *x += 5;
296 /// If we were to try to translate this closure into a more explicit
297 /// form, we'd encounter an error with the code as written:
299 /// struct Env { x: & &mut isize }
300 /// let x: &mut isize = ...;
301 /// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn
302 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
304 /// This is then illegal because you cannot mutate a `&mut` found
305 /// in an aliasable location. To solve, you'd have to translate with
306 /// an `&mut` borrow:
308 /// struct Env { x: & &mut isize }
309 /// let x: &mut isize = ...;
310 /// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x
311 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
313 /// Now the assignment to `**env.x` is legal, but creating a
314 /// mutable pointer to `x` is not because `x` is not mutable. We
315 /// could fix this by declaring `x` as `let mut x`. This is ok in
316 /// user code, if awkward, but extra weird for closures, since the
317 /// borrow is hidden.
319 /// So we introduce a "unique imm" borrow -- the referent is
320 /// immutable, but not aliasable. This solves the problem. For
321 /// simplicity, we don't give users the way to express this
322 /// borrow, it's just used when translating closures.
325 /// Data is mutable and not aliasable.
329 ///////////////////////////////////////////////////////////////////////////
330 // Variables and temps
332 newtype_index!(Local, "_");
334 pub const RETURN_POINTER: Local = Local(0);
336 /// Classifies locals into categories. See `Mir::local_kind`.
337 #[derive(PartialEq, Eq, Debug)]
339 /// User-declared variable binding
341 /// Compiler-introduced temporary
343 /// Function argument
345 /// Location of function's return value
351 /// This can be a binding declared by the user, a temporary inserted by the compiler, a function
352 /// argument, or the return pointer.
353 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
354 pub struct LocalDecl<'tcx> {
355 /// `let mut x` vs `let x`.
357 /// Temporaries and the return pointer are always mutable.
358 pub mutability: Mutability,
360 /// Type of this local.
363 /// Name of the local, used in debuginfo and pretty-printing.
365 /// Note that function arguments can also have this set to `Some(_)`
366 /// to generate better debuginfo.
367 pub name: Option<Name>,
369 /// For user-declared variables, stores their source information.
371 /// For temporaries, this is `None`.
373 /// This is the primary way to differentiate between user-declared
374 /// variables and compiler-generated temporaries.
375 pub source_info: Option<SourceInfo>,
378 impl<'tcx> LocalDecl<'tcx> {
379 /// Create a new `LocalDecl` for a temporary.
381 pub fn new_temp(ty: Ty<'tcx>) -> Self {
383 mutability: Mutability::Mut,
390 /// Builds a `LocalDecl` for the return pointer.
392 /// This must be inserted into the `local_decls` list as the first local.
394 pub fn new_return_pointer(return_ty: Ty) -> LocalDecl {
396 mutability: Mutability::Mut,
399 name: None, // FIXME maybe we do want some name here?
404 /// A closure capture, with its name and mode.
405 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
406 pub struct UpvarDecl {
407 pub debug_name: Name,
409 /// If true, the capture is behind a reference.
413 ///////////////////////////////////////////////////////////////////////////
416 newtype_index!(BasicBlock, "bb");
418 ///////////////////////////////////////////////////////////////////////////
419 // BasicBlockData and Terminator
421 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
422 pub struct BasicBlockData<'tcx> {
423 /// List of statements in this block.
424 pub statements: Vec<Statement<'tcx>>,
426 /// Terminator for this block.
428 /// NB. This should generally ONLY be `None` during construction.
429 /// Therefore, you should generally access it via the
430 /// `terminator()` or `terminator_mut()` methods. The only
431 /// exception is that certain passes, such as `simplify_cfg`, swap
432 /// out the terminator temporarily with `None` while they continue
433 /// to recurse over the set of basic blocks.
434 pub terminator: Option<Terminator<'tcx>>,
436 /// If true, this block lies on an unwind path. This is used
437 /// during trans where distinct kinds of basic blocks may be
438 /// generated (particularly for MSVC cleanup). Unwind blocks must
439 /// only branch to other unwind blocks.
440 pub is_cleanup: bool,
443 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
444 pub struct Terminator<'tcx> {
445 pub source_info: SourceInfo,
446 pub kind: TerminatorKind<'tcx>
449 #[derive(Clone, RustcEncodable, RustcDecodable)]
450 pub enum TerminatorKind<'tcx> {
451 /// block should have one successor in the graph; we jump there
456 /// jump to branch 0 if this lvalue evaluates to true
459 targets: (BasicBlock, BasicBlock),
462 /// lvalue evaluates to some enum; jump depending on the branch
465 adt_def: &'tcx AdtDef,
466 targets: Vec<BasicBlock>,
469 /// operand evaluates to an integer; jump depending on its value
470 /// to one of the targets, and otherwise fallback to `otherwise`
472 /// discriminant value being tested
475 /// type of value being tested
478 /// Possible values. The locations to branch to in each case
479 /// are found in the corresponding indices from the `targets` vector.
480 values: Vec<ConstVal>,
482 /// Possible branch sites. The length of this vector should be
483 /// equal to the length of the `values` vector plus 1 -- the
484 /// extra item is the block to branch to if none of the values
486 targets: Vec<BasicBlock>,
489 /// Indicates that the landing pad is finished and unwinding should
490 /// continue. Emitted by build::scope::diverge_cleanup.
493 /// Indicates a normal return. The return pointer lvalue should
494 /// have been filled in by now. This should occur at most once.
497 /// Indicates a terminator that can never be reached.
502 location: Lvalue<'tcx>,
504 unwind: Option<BasicBlock>
507 /// Drop the Lvalue and assign the new value over it
509 location: Lvalue<'tcx>,
510 value: Operand<'tcx>,
512 unwind: Option<BasicBlock>,
515 /// Block ends with a call of a converging function
517 /// The function that’s being called
519 /// Arguments the function is called with
520 args: Vec<Operand<'tcx>>,
521 /// Destination for the return value. If some, the call is converging.
522 destination: Option<(Lvalue<'tcx>, BasicBlock)>,
523 /// Cleanups to be done if the call unwinds.
524 cleanup: Option<BasicBlock>
527 /// Jump to the target if the condition has the expected value,
528 /// otherwise panic with a message and a cleanup target.
532 msg: AssertMessage<'tcx>,
534 cleanup: Option<BasicBlock>
538 impl<'tcx> Terminator<'tcx> {
539 pub fn successors(&self) -> Cow<[BasicBlock]> {
540 self.kind.successors()
543 pub fn successors_mut(&mut self) -> Vec<&mut BasicBlock> {
544 self.kind.successors_mut()
548 impl<'tcx> TerminatorKind<'tcx> {
549 pub fn successors(&self) -> Cow<[BasicBlock]> {
550 use self::TerminatorKind::*;
552 Goto { target: ref b } => slice::ref_slice(b).into_cow(),
553 If { targets: (b1, b2), .. } => vec![b1, b2].into_cow(),
554 Switch { targets: ref b, .. } => b[..].into_cow(),
555 SwitchInt { targets: ref b, .. } => b[..].into_cow(),
556 Resume => (&[]).into_cow(),
557 Return => (&[]).into_cow(),
558 Unreachable => (&[]).into_cow(),
559 Call { destination: Some((_, t)), cleanup: Some(c), .. } => vec![t, c].into_cow(),
560 Call { destination: Some((_, ref t)), cleanup: None, .. } =>
561 slice::ref_slice(t).into_cow(),
562 Call { destination: None, cleanup: Some(ref c), .. } => slice::ref_slice(c).into_cow(),
563 Call { destination: None, cleanup: None, .. } => (&[]).into_cow(),
564 DropAndReplace { target, unwind: Some(unwind), .. } |
565 Drop { target, unwind: Some(unwind), .. } => {
566 vec![target, unwind].into_cow()
568 DropAndReplace { ref target, unwind: None, .. } |
569 Drop { ref target, unwind: None, .. } => {
570 slice::ref_slice(target).into_cow()
572 Assert { target, cleanup: Some(unwind), .. } => vec![target, unwind].into_cow(),
573 Assert { ref target, .. } => slice::ref_slice(target).into_cow(),
577 // FIXME: no mootable cow. I’m honestly not sure what a “cow” between `&mut [BasicBlock]` and
578 // `Vec<&mut BasicBlock>` would look like in the first place.
579 pub fn successors_mut(&mut self) -> Vec<&mut BasicBlock> {
580 use self::TerminatorKind::*;
582 Goto { target: ref mut b } => vec![b],
583 If { targets: (ref mut b1, ref mut b2), .. } => vec![b1, b2],
584 Switch { targets: ref mut b, .. } => b.iter_mut().collect(),
585 SwitchInt { targets: ref mut b, .. } => b.iter_mut().collect(),
586 Resume => Vec::new(),
587 Return => Vec::new(),
588 Unreachable => Vec::new(),
589 Call { destination: Some((_, ref mut t)), cleanup: Some(ref mut c), .. } => vec![t, c],
590 Call { destination: Some((_, ref mut t)), cleanup: None, .. } => vec![t],
591 Call { destination: None, cleanup: Some(ref mut c), .. } => vec![c],
592 Call { destination: None, cleanup: None, .. } => vec![],
593 DropAndReplace { ref mut target, unwind: Some(ref mut unwind), .. } |
594 Drop { ref mut target, unwind: Some(ref mut unwind), .. } => vec![target, unwind],
595 DropAndReplace { ref mut target, unwind: None, .. } |
596 Drop { ref mut target, unwind: None, .. } => {
599 Assert { ref mut target, cleanup: Some(ref mut unwind), .. } => vec![target, unwind],
600 Assert { ref mut target, .. } => vec![target]
605 impl<'tcx> BasicBlockData<'tcx> {
606 pub fn new(terminator: Option<Terminator<'tcx>>) -> BasicBlockData<'tcx> {
609 terminator: terminator,
614 /// Accessor for terminator.
616 /// Terminator may not be None after construction of the basic block is complete. This accessor
617 /// provides a convenience way to reach the terminator.
618 pub fn terminator(&self) -> &Terminator<'tcx> {
619 self.terminator.as_ref().expect("invalid terminator state")
622 pub fn terminator_mut(&mut self) -> &mut Terminator<'tcx> {
623 self.terminator.as_mut().expect("invalid terminator state")
627 impl<'tcx> Debug for TerminatorKind<'tcx> {
628 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
630 let successors = self.successors();
631 let labels = self.fmt_successor_labels();
632 assert_eq!(successors.len(), labels.len());
634 match successors.len() {
637 1 => write!(fmt, " -> {:?}", successors[0]),
640 write!(fmt, " -> [")?;
641 for (i, target) in successors.iter().enumerate() {
645 write!(fmt, "{}: {:?}", labels[i], target)?;
654 impl<'tcx> TerminatorKind<'tcx> {
655 /// Write the "head" part of the terminator; that is, its name and the data it uses to pick the
656 /// successor basic block, if any. The only information not inlcuded is the list of possible
657 /// successors, which may be rendered differently between the text and the graphviz format.
658 pub fn fmt_head<W: Write>(&self, fmt: &mut W) -> fmt::Result {
659 use self::TerminatorKind::*;
661 Goto { .. } => write!(fmt, "goto"),
662 If { cond: ref lv, .. } => write!(fmt, "if({:?})", lv),
663 Switch { discr: ref lv, .. } => write!(fmt, "switch({:?})", lv),
664 SwitchInt { discr: ref lv, .. } => write!(fmt, "switchInt({:?})", lv),
665 Return => write!(fmt, "return"),
666 Resume => write!(fmt, "resume"),
667 Unreachable => write!(fmt, "unreachable"),
668 Drop { ref location, .. } => write!(fmt, "drop({:?})", location),
669 DropAndReplace { ref location, ref value, .. } =>
670 write!(fmt, "replace({:?} <- {:?})", location, value),
671 Call { ref func, ref args, ref destination, .. } => {
672 if let Some((ref destination, _)) = *destination {
673 write!(fmt, "{:?} = ", destination)?;
675 write!(fmt, "{:?}(", func)?;
676 for (index, arg) in args.iter().enumerate() {
680 write!(fmt, "{:?}", arg)?;
684 Assert { ref cond, expected, ref msg, .. } => {
685 write!(fmt, "assert(")?;
689 write!(fmt, "{:?}, ", cond)?;
692 AssertMessage::BoundsCheck { ref len, ref index } => {
693 write!(fmt, "{:?}, {:?}, {:?}",
694 "index out of bounds: the len is {} but the index is {}",
697 AssertMessage::Math(ref err) => {
698 write!(fmt, "{:?}", err.description())?;
707 /// Return the list of labels for the edges to the successor basic blocks.
708 pub fn fmt_successor_labels(&self) -> Vec<Cow<'static, str>> {
709 use self::TerminatorKind::*;
711 Return | Resume | Unreachable => vec![],
712 Goto { .. } => vec!["".into()],
713 If { .. } => vec!["true".into(), "false".into()],
714 Switch { ref adt_def, .. } => {
717 .map(|variant| variant.name.to_string().into())
720 SwitchInt { ref values, .. } => {
723 let mut buf = String::new();
724 fmt_const_val(&mut buf, const_val).unwrap();
727 .chain(iter::once(String::from("otherwise").into()))
730 Call { destination: Some(_), cleanup: Some(_), .. } =>
731 vec!["return".into_cow(), "unwind".into_cow()],
732 Call { destination: Some(_), cleanup: None, .. } => vec!["return".into_cow()],
733 Call { destination: None, cleanup: Some(_), .. } => vec!["unwind".into_cow()],
734 Call { destination: None, cleanup: None, .. } => vec![],
735 DropAndReplace { unwind: None, .. } |
736 Drop { unwind: None, .. } => vec!["return".into_cow()],
737 DropAndReplace { unwind: Some(_), .. } |
738 Drop { unwind: Some(_), .. } => {
739 vec!["return".into_cow(), "unwind".into_cow()]
741 Assert { cleanup: None, .. } => vec!["".into()],
743 vec!["success".into_cow(), "unwind".into_cow()]
748 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
749 pub enum AssertMessage<'tcx> {
757 ///////////////////////////////////////////////////////////////////////////
760 #[derive(Clone, RustcEncodable, RustcDecodable)]
761 pub struct Statement<'tcx> {
762 pub source_info: SourceInfo,
763 pub kind: StatementKind<'tcx>,
766 impl<'tcx> Statement<'tcx> {
767 /// Changes a statement to a nop. This is both faster than deleting instructions and avoids
768 /// invalidating statement indices in `Location`s.
769 pub fn make_nop(&mut self) {
770 self.kind = StatementKind::Nop
774 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
775 pub enum StatementKind<'tcx> {
776 /// Write the RHS Rvalue to the LHS Lvalue.
777 Assign(Lvalue<'tcx>, Rvalue<'tcx>),
779 /// Write the discriminant for a variant to the enum Lvalue.
780 SetDiscriminant { lvalue: Lvalue<'tcx>, variant_index: usize },
782 /// Start a live range for the storage of the local.
783 StorageLive(Lvalue<'tcx>),
785 /// End the current live range for the storage of the local.
786 StorageDead(Lvalue<'tcx>),
788 /// No-op. Useful for deleting instructions without affecting statement indices.
792 impl<'tcx> Debug for Statement<'tcx> {
793 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
794 use self::StatementKind::*;
796 Assign(ref lv, ref rv) => write!(fmt, "{:?} = {:?}", lv, rv),
797 StorageLive(ref lv) => write!(fmt, "StorageLive({:?})", lv),
798 StorageDead(ref lv) => write!(fmt, "StorageDead({:?})", lv),
799 SetDiscriminant{lvalue: ref lv, variant_index: index} => {
800 write!(fmt, "discriminant({:?}) = {:?}", lv, index)
802 Nop => write!(fmt, "nop"),
807 ///////////////////////////////////////////////////////////////////////////
810 /// A path to a value; something that can be evaluated without
811 /// changing or disturbing program state.
812 #[derive(Clone, PartialEq, RustcEncodable, RustcDecodable)]
813 pub enum Lvalue<'tcx> {
817 /// static or static mut variable
820 /// projection out of an lvalue (access a field, deref a pointer, etc)
821 Projection(Box<LvalueProjection<'tcx>>),
824 /// The `Projection` data structure defines things of the form `B.x`
825 /// or `*B` or `B[index]`. Note that it is parameterized because it is
826 /// shared between `Constant` and `Lvalue`. See the aliases
827 /// `LvalueProjection` etc below.
828 #[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
829 pub struct Projection<'tcx, B, V> {
831 pub elem: ProjectionElem<'tcx, V>,
834 #[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
835 pub enum ProjectionElem<'tcx, V> {
837 Field(Field, Ty<'tcx>),
840 /// These indices are generated by slice patterns. Easiest to explain
844 /// [X, _, .._, _, _] => { offset: 0, min_length: 4, from_end: false },
845 /// [_, X, .._, _, _] => { offset: 1, min_length: 4, from_end: false },
846 /// [_, _, .._, X, _] => { offset: 2, min_length: 4, from_end: true },
847 /// [_, _, .._, _, X] => { offset: 1, min_length: 4, from_end: true },
850 /// index or -index (in Python terms), depending on from_end
852 /// thing being indexed must be at least this long
854 /// counting backwards from end?
858 /// These indices are generated by slice patterns.
860 /// slice[from:-to] in Python terms.
866 /// "Downcast" to a variant of an ADT. Currently, we only introduce
867 /// this for ADTs with more than one variant. It may be better to
868 /// just introduce it always, or always for enums.
869 Downcast(&'tcx AdtDef, usize),
872 /// Alias for projections as they appear in lvalues, where the base is an lvalue
873 /// and the index is an operand.
874 pub type LvalueProjection<'tcx> = Projection<'tcx, Lvalue<'tcx>, Operand<'tcx>>;
876 /// Alias for projections as they appear in lvalues, where the base is an lvalue
877 /// and the index is an operand.
878 pub type LvalueElem<'tcx> = ProjectionElem<'tcx, Operand<'tcx>>;
880 newtype_index!(Field, "field");
882 impl<'tcx> Lvalue<'tcx> {
883 pub fn field(self, f: Field, ty: Ty<'tcx>) -> Lvalue<'tcx> {
884 self.elem(ProjectionElem::Field(f, ty))
887 pub fn deref(self) -> Lvalue<'tcx> {
888 self.elem(ProjectionElem::Deref)
891 pub fn downcast(self, adt_def: &'tcx AdtDef, variant_index: usize) -> Lvalue<'tcx> {
892 self.elem(ProjectionElem::Downcast(adt_def, variant_index))
895 pub fn index(self, index: Operand<'tcx>) -> Lvalue<'tcx> {
896 self.elem(ProjectionElem::Index(index))
899 pub fn elem(self, elem: LvalueElem<'tcx>) -> Lvalue<'tcx> {
900 Lvalue::Projection(Box::new(LvalueProjection {
907 impl<'tcx> Debug for Lvalue<'tcx> {
908 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
912 Local(id) => write!(fmt, "{:?}", id),
914 write!(fmt, "{}", ty::tls::with(|tcx| tcx.item_path_str(def_id))),
915 Projection(ref data) =>
917 ProjectionElem::Downcast(ref adt_def, index) =>
918 write!(fmt, "({:?} as {})", data.base, adt_def.variants[index].name),
919 ProjectionElem::Deref =>
920 write!(fmt, "(*{:?})", data.base),
921 ProjectionElem::Field(field, ty) =>
922 write!(fmt, "({:?}.{:?}: {:?})", data.base, field.index(), ty),
923 ProjectionElem::Index(ref index) =>
924 write!(fmt, "{:?}[{:?}]", data.base, index),
925 ProjectionElem::ConstantIndex { offset, min_length, from_end: false } =>
926 write!(fmt, "{:?}[{:?} of {:?}]", data.base, offset, min_length),
927 ProjectionElem::ConstantIndex { offset, min_length, from_end: true } =>
928 write!(fmt, "{:?}[-{:?} of {:?}]", data.base, offset, min_length),
929 ProjectionElem::Subslice { from, to } if to == 0 =>
930 write!(fmt, "{:?}[{:?}:]", data.base, from),
931 ProjectionElem::Subslice { from, to } if from == 0 =>
932 write!(fmt, "{:?}[:-{:?}]", data.base, to),
933 ProjectionElem::Subslice { from, to } =>
934 write!(fmt, "{:?}[{:?}:-{:?}]", data.base,
942 ///////////////////////////////////////////////////////////////////////////
945 newtype_index!(VisibilityScope, "scope");
946 pub const ARGUMENT_VISIBILITY_SCOPE : VisibilityScope = VisibilityScope(0);
948 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
949 pub struct VisibilityScopeData {
951 pub parent_scope: Option<VisibilityScope>,
954 ///////////////////////////////////////////////////////////////////////////
957 /// These are values that can appear inside an rvalue (or an index
958 /// lvalue). They are intentionally limited to prevent rvalues from
959 /// being nested in one another.
960 #[derive(Clone, PartialEq, RustcEncodable, RustcDecodable)]
961 pub enum Operand<'tcx> {
962 Consume(Lvalue<'tcx>),
963 Constant(Constant<'tcx>),
966 impl<'tcx> Debug for Operand<'tcx> {
967 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
968 use self::Operand::*;
970 Constant(ref a) => write!(fmt, "{:?}", a),
971 Consume(ref lv) => write!(fmt, "{:?}", lv),
976 ///////////////////////////////////////////////////////////////////////////
979 #[derive(Clone, RustcEncodable, RustcDecodable)]
980 pub enum Rvalue<'tcx> {
981 /// x (either a move or copy, depending on type of x)
985 Repeat(Operand<'tcx>, TypedConstVal<'tcx>),
988 Ref(&'tcx Region, BorrowKind, Lvalue<'tcx>),
990 /// length of a [X] or [X;n] value
993 Cast(CastKind, Operand<'tcx>, Ty<'tcx>),
995 BinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>),
996 CheckedBinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>),
998 UnaryOp(UnOp, Operand<'tcx>),
1000 /// Creates an *uninitialized* Box
1003 /// Create an aggregate value, like a tuple or struct. This is
1004 /// only needed because we want to distinguish `dest = Foo { x:
1005 /// ..., y: ... }` from `dest.x = ...; dest.y = ...;` in the case
1006 /// that `Foo` has a destructor. These rvalues can be optimized
1007 /// away after type-checking and before lowering.
1008 Aggregate(AggregateKind<'tcx>, Vec<Operand<'tcx>>),
1012 outputs: Vec<Lvalue<'tcx>>,
1013 inputs: Vec<Operand<'tcx>>
1017 #[derive(Clone, Copy, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
1021 /// Convert unique, zero-sized type for a fn to fn()
1024 /// Convert safe fn() to unsafe fn()
1027 /// "Unsize" -- convert a thin-or-fat pointer to a fat pointer.
1028 /// trans must figure out the details once full monomorphization
1029 /// is known. For example, this could be used to cast from a
1030 /// `&[i32;N]` to a `&[i32]`, or a `Box<T>` to a `Box<Trait>`
1031 /// (presuming `T: Trait`).
1035 #[derive(Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
1036 pub enum AggregateKind<'tcx> {
1039 /// The second field is variant number (discriminant), it's equal to 0
1040 /// for struct and union expressions. The fourth field is active field
1041 /// number and is present only for union expressions.
1042 Adt(&'tcx AdtDef, usize, &'tcx Substs<'tcx>, Option<usize>),
1043 Closure(DefId, ClosureSubsts<'tcx>),
1046 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
1048 /// The `+` operator (addition)
1050 /// The `-` operator (subtraction)
1052 /// The `*` operator (multiplication)
1054 /// The `/` operator (division)
1056 /// The `%` operator (modulus)
1058 /// The `^` operator (bitwise xor)
1060 /// The `&` operator (bitwise and)
1062 /// The `|` operator (bitwise or)
1064 /// The `<<` operator (shift left)
1066 /// The `>>` operator (shift right)
1068 /// The `==` operator (equality)
1070 /// The `<` operator (less than)
1072 /// The `<=` operator (less than or equal to)
1074 /// The `!=` operator (not equal to)
1076 /// The `>=` operator (greater than or equal to)
1078 /// The `>` operator (greater than)
1083 pub fn is_checkable(self) -> bool {
1086 Add | Sub | Mul | Shl | Shr => true,
1092 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
1094 /// The `!` operator for logical inversion
1096 /// The `-` operator for negation
1100 impl<'tcx> Debug for Rvalue<'tcx> {
1101 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1102 use self::Rvalue::*;
1105 Use(ref lvalue) => write!(fmt, "{:?}", lvalue),
1106 Repeat(ref a, ref b) => write!(fmt, "[{:?}; {:?}]", a, b),
1107 Len(ref a) => write!(fmt, "Len({:?})", a),
1108 Cast(ref kind, ref lv, ref ty) => write!(fmt, "{:?} as {:?} ({:?})", lv, ty, kind),
1109 BinaryOp(ref op, ref a, ref b) => write!(fmt, "{:?}({:?}, {:?})", op, a, b),
1110 CheckedBinaryOp(ref op, ref a, ref b) => {
1111 write!(fmt, "Checked{:?}({:?}, {:?})", op, a, b)
1113 UnaryOp(ref op, ref a) => write!(fmt, "{:?}({:?})", op, a),
1114 Box(ref t) => write!(fmt, "Box({:?})", t),
1115 InlineAsm { ref asm, ref outputs, ref inputs } => {
1116 write!(fmt, "asm!({:?} : {:?} : {:?})", asm, outputs, inputs)
1119 Ref(_, borrow_kind, ref lv) => {
1120 let kind_str = match borrow_kind {
1121 BorrowKind::Shared => "",
1122 BorrowKind::Mut | BorrowKind::Unique => "mut ",
1124 write!(fmt, "&{}{:?}", kind_str, lv)
1127 Aggregate(ref kind, ref lvs) => {
1128 fn fmt_tuple(fmt: &mut Formatter, lvs: &[Operand]) -> fmt::Result {
1129 let mut tuple_fmt = fmt.debug_tuple("");
1131 tuple_fmt.field(lv);
1137 AggregateKind::Array => write!(fmt, "{:?}", lvs),
1139 AggregateKind::Tuple => {
1141 0 => write!(fmt, "()"),
1142 1 => write!(fmt, "({:?},)", lvs[0]),
1143 _ => fmt_tuple(fmt, lvs),
1147 AggregateKind::Adt(adt_def, variant, substs, _) => {
1148 let variant_def = &adt_def.variants[variant];
1150 ppaux::parameterized(fmt, substs, variant_def.did, &[])?;
1152 match variant_def.ctor_kind {
1153 CtorKind::Const => Ok(()),
1154 CtorKind::Fn => fmt_tuple(fmt, lvs),
1155 CtorKind::Fictive => {
1156 let mut struct_fmt = fmt.debug_struct("");
1157 for (field, lv) in variant_def.fields.iter().zip(lvs) {
1158 struct_fmt.field(&field.name.as_str(), lv);
1165 AggregateKind::Closure(def_id, _) => ty::tls::with(|tcx| {
1166 if let Some(node_id) = tcx.hir.as_local_node_id(def_id) {
1167 let name = format!("[closure@{:?}]", tcx.hir.span(node_id));
1168 let mut struct_fmt = fmt.debug_struct(&name);
1170 tcx.with_freevars(node_id, |freevars| {
1171 for (freevar, lv) in freevars.iter().zip(lvs) {
1172 let def_id = freevar.def.def_id();
1173 let var_id = tcx.hir.as_local_node_id(def_id).unwrap();
1174 let var_name = tcx.local_var_name_str(var_id);
1175 struct_fmt.field(&var_name, lv);
1181 write!(fmt, "[closure]")
1190 ///////////////////////////////////////////////////////////////////////////
1193 /// Two constants are equal if they are the same constant. Note that
1194 /// this does not necessarily mean that they are "==" in Rust -- in
1195 /// particular one must be wary of `NaN`!
1197 #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1198 pub struct Constant<'tcx> {
1201 pub literal: Literal<'tcx>,
1204 #[derive(Clone, RustcEncodable, RustcDecodable)]
1205 pub struct TypedConstVal<'tcx> {
1208 pub value: ConstUsize,
1211 impl<'tcx> Debug for TypedConstVal<'tcx> {
1212 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1213 write!(fmt, "const {}", ConstInt::Usize(self.value))
1217 newtype_index!(Promoted, "promoted");
1219 #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1220 pub enum Literal<'tcx> {
1223 substs: &'tcx Substs<'tcx>,
1229 // Index into the `promoted` vector of `Mir`.
1234 impl<'tcx> Debug for Constant<'tcx> {
1235 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1236 write!(fmt, "{:?}", self.literal)
1240 impl<'tcx> Debug for Literal<'tcx> {
1241 fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
1242 use self::Literal::*;
1244 Item { def_id, substs } => {
1245 ppaux::parameterized(fmt, substs, def_id, &[])
1247 Value { ref value } => {
1248 write!(fmt, "const ")?;
1249 fmt_const_val(fmt, value)
1251 Promoted { index } => {
1252 write!(fmt, "{:?}", index)
1258 /// Write a `ConstVal` in a way closer to the original source code than the `Debug` output.
1259 fn fmt_const_val<W: Write>(fmt: &mut W, const_val: &ConstVal) -> fmt::Result {
1260 use middle::const_val::ConstVal::*;
1262 Float(f) => write!(fmt, "{:?}", f),
1263 Integral(n) => write!(fmt, "{}", n),
1264 Str(ref s) => write!(fmt, "{:?}", s),
1265 ByteStr(ref bytes) => {
1266 let escaped: String = bytes
1268 .flat_map(|&ch| ascii::escape_default(ch).map(|c| c as char))
1270 write!(fmt, "b\"{}\"", escaped)
1272 Bool(b) => write!(fmt, "{:?}", b),
1273 Function(def_id) => write!(fmt, "{}", item_path_str(def_id)),
1274 Struct(_) | Tuple(_) | Array(_) | Repeat(..) =>
1275 bug!("ConstVal `{:?}` should not be in MIR", const_val),
1276 Char(c) => write!(fmt, "{:?}", c),
1280 fn item_path_str(def_id: DefId) -> String {
1281 ty::tls::with(|tcx| tcx.item_path_str(def_id))
1284 impl<'tcx> ControlFlowGraph for Mir<'tcx> {
1286 type Node = BasicBlock;
1288 fn num_nodes(&self) -> usize { self.basic_blocks.len() }
1290 fn start_node(&self) -> Self::Node { START_BLOCK }
1292 fn predecessors<'graph>(&'graph self, node: Self::Node)
1293 -> <Self as GraphPredecessors<'graph>>::Iter
1295 self.predecessors_for(node).clone().into_iter()
1297 fn successors<'graph>(&'graph self, node: Self::Node)
1298 -> <Self as GraphSuccessors<'graph>>::Iter
1300 self.basic_blocks[node].terminator().successors().into_owned().into_iter()
1304 impl<'a, 'b> GraphPredecessors<'b> for Mir<'a> {
1305 type Item = BasicBlock;
1306 type Iter = IntoIter<BasicBlock>;
1309 impl<'a, 'b> GraphSuccessors<'b> for Mir<'a> {
1310 type Item = BasicBlock;
1311 type Iter = IntoIter<BasicBlock>;
1314 #[derive(Copy, Clone, PartialEq, Eq, Hash, Ord, PartialOrd)]
1315 pub struct Location {
1316 /// the location is within this block
1317 pub block: BasicBlock,
1319 /// the location is the start of the this statement; or, if `statement_index`
1320 /// == num-statements, then the start of the terminator.
1321 pub statement_index: usize,
1324 impl fmt::Debug for Location {
1325 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
1326 write!(fmt, "{:?}[{}]", self.block, self.statement_index)
1331 pub fn dominates(&self, other: &Location, dominators: &Dominators<BasicBlock>) -> bool {
1332 if self.block == other.block {
1333 self.statement_index <= other.statement_index
1335 dominators.is_dominated_by(other.block, self.block)