| use crate::mir::interpret::Scalar; |
| use crate::ty::{self, Ty, TyCtxt}; |
| use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece}; |
| use smallvec::{smallvec, SmallVec}; |
| |
| use super::{ |
| AssertMessage, BasicBlock, InlineAsmOperand, Operand, Place, SourceInfo, Successors, |
| SuccessorsMut, |
| }; |
| pub use rustc_ast::Mutability; |
| use rustc_macros::HashStable; |
| use rustc_span::Span; |
| use std::borrow::Cow; |
| use std::fmt::{self, Debug, Formatter, Write}; |
| use std::iter; |
| use std::slice; |
| |
| pub use super::query::*; |
| |
| #[derive(Debug, Clone, TyEncodable, TyDecodable, HashStable, PartialEq)] |
| pub struct SwitchTargets { |
| /// Possible values. The locations to branch to in each case |
| /// are found in the corresponding indices from the `targets` vector. |
| values: SmallVec<[u128; 1]>, |
| |
| /// Possible branch sites. The last element of this vector is used |
| /// for the otherwise branch, so targets.len() == values.len() + 1 |
| /// should hold. |
| // |
| // This invariant is quite non-obvious and also could be improved. |
| // One way to make this invariant is to have something like this instead: |
| // |
| // branches: Vec<(ConstInt, BasicBlock)>, |
| // otherwise: Option<BasicBlock> // exhaustive if None |
| // |
| // However we’ve decided to keep this as-is until we figure a case |
| // where some other approach seems to be strictly better than other. |
| targets: SmallVec<[BasicBlock; 2]>, |
| } |
| |
| impl SwitchTargets { |
| /// Creates switch targets from an iterator of values and target blocks. |
| /// |
| /// The iterator may be empty, in which case the `SwitchInt` instruction is equivalent to |
| /// `goto otherwise;`. |
| pub fn new(targets: impl Iterator<Item = (u128, BasicBlock)>, otherwise: BasicBlock) -> Self { |
| let (values, mut targets): (SmallVec<_>, SmallVec<_>) = targets.unzip(); |
| targets.push(otherwise); |
| Self { values: values.into(), targets } |
| } |
| |
| /// Builds a switch targets definition that jumps to `then` if the tested value equals `value`, |
| /// and to `else_` if not. |
| pub fn static_if(value: u128, then: BasicBlock, else_: BasicBlock) -> Self { |
| Self { values: smallvec![value], targets: smallvec![then, else_] } |
| } |
| |
| /// Returns the fallback target that is jumped to when none of the values match the operand. |
| pub fn otherwise(&self) -> BasicBlock { |
| *self.targets.last().unwrap() |
| } |
| |
| /// Returns an iterator over the switch targets. |
| /// |
| /// The iterator will yield tuples containing the value and corresponding target to jump to, not |
| /// including the `otherwise` fallback target. |
| /// |
| /// Note that this may yield 0 elements. Only the `otherwise` branch is mandatory. |
| pub fn iter(&self) -> SwitchTargetsIter<'_> { |
| SwitchTargetsIter { inner: self.values.iter().zip(self.targets.iter()) } |
| } |
| |
| /// Returns a slice with all possible jump targets (including the fallback target). |
| pub fn all_targets(&self) -> &[BasicBlock] { |
| &self.targets |
| } |
| |
| pub fn all_targets_mut(&mut self) -> &mut [BasicBlock] { |
| &mut self.targets |
| } |
| } |
| |
| pub struct SwitchTargetsIter<'a> { |
| inner: iter::Zip<slice::Iter<'a, u128>, slice::Iter<'a, BasicBlock>>, |
| } |
| |
| impl<'a> Iterator for SwitchTargetsIter<'a> { |
| type Item = (u128, BasicBlock); |
| |
| fn next(&mut self) -> Option<Self::Item> { |
| self.inner.next().map(|(val, bb)| (*val, *bb)) |
| } |
| |
| fn size_hint(&self) -> (usize, Option<usize>) { |
| self.inner.size_hint() |
| } |
| } |
| |
| impl<'a> ExactSizeIterator for SwitchTargetsIter<'a> {} |
| |
| #[derive(Clone, TyEncodable, TyDecodable, HashStable, PartialEq)] |
| pub enum TerminatorKind<'tcx> { |
| /// Block should have one successor in the graph; we jump there. |
| Goto { target: BasicBlock }, |
| |
| /// Operand evaluates to an integer; jump depending on its value |
| /// to one of the targets, and otherwise fallback to `otherwise`. |
| SwitchInt { |
| /// The discriminant value being tested. |
| discr: Operand<'tcx>, |
| |
| /// The type of value being tested. |
| /// This is always the same as the type of `discr`. |
| /// FIXME: remove this redundant information. Currently, it is relied on by pretty-printing. |
| switch_ty: Ty<'tcx>, |
| |
| targets: SwitchTargets, |
| }, |
| |
| /// Indicates that the landing pad is finished and unwinding should |
| /// continue. Emitted by `build::scope::diverge_cleanup`. |
| Resume, |
| |
| /// Indicates that the landing pad is finished and that the process |
| /// should abort. Used to prevent unwinding for foreign items. |
| Abort, |
| |
| /// Indicates a normal return. The return place should have |
| /// been filled in before this executes. This can occur multiple times |
| /// in different basic blocks. |
| Return, |
| |
| /// Indicates a terminator that can never be reached. |
| Unreachable, |
| |
| /// Drop the `Place`. |
| Drop { place: Place<'tcx>, target: BasicBlock, unwind: Option<BasicBlock> }, |
| |
| /// Drop the `Place` and assign the new value over it. This ensures |
| /// that the assignment to `P` occurs *even if* the destructor for |
| /// place unwinds. Its semantics are best explained by the |
| /// elaboration: |
| /// |
| /// ``` |
| /// BB0 { |
| /// DropAndReplace(P <- V, goto BB1, unwind BB2) |
| /// } |
| /// ``` |
| /// |
| /// becomes |
| /// |
| /// ``` |
| /// BB0 { |
| /// Drop(P, goto BB1, unwind BB2) |
| /// } |
| /// BB1 { |
| /// // P is now uninitialized |
| /// P <- V |
| /// } |
| /// BB2 { |
| /// // P is now uninitialized -- its dtor panicked |
| /// P <- V |
| /// } |
| /// ``` |
| /// |
| /// Note that DropAndReplace is eliminated as part of the `ElaborateDrops` pass. |
| DropAndReplace { |
| place: Place<'tcx>, |
| value: Operand<'tcx>, |
| target: BasicBlock, |
| unwind: Option<BasicBlock>, |
| }, |
| |
| /// Block ends with a call of a function. |
| Call { |
| /// The function that’s being called. |
| func: Operand<'tcx>, |
| /// Arguments the function is called with. |
| /// These are owned by the callee, which is free to modify them. |
| /// This allows the memory occupied by "by-value" arguments to be |
| /// reused across function calls without duplicating the contents. |
| args: Vec<Operand<'tcx>>, |
| /// Destination for the return value. If some, the call is converging. |
| destination: Option<(Place<'tcx>, BasicBlock)>, |
| /// Cleanups to be done if the call unwinds. |
| cleanup: Option<BasicBlock>, |
| /// `true` if this is from a call in HIR rather than from an overloaded |
| /// operator. True for overloaded function call. |
| from_hir_call: bool, |
| /// This `Span` is the span of the function, without the dot and receiver |
| /// (e.g. `foo(a, b)` in `x.foo(a, b)` |
| fn_span: Span, |
| }, |
| |
| /// Jump to the target if the condition has the expected value, |
| /// otherwise panic with a message and a cleanup target. |
| Assert { |
| cond: Operand<'tcx>, |
| expected: bool, |
| msg: AssertMessage<'tcx>, |
| target: BasicBlock, |
| cleanup: Option<BasicBlock>, |
| }, |
| |
| /// A suspend point. |
| Yield { |
| /// The value to return. |
| value: Operand<'tcx>, |
| /// Where to resume to. |
| resume: BasicBlock, |
| /// The place to store the resume argument in. |
| resume_arg: Place<'tcx>, |
| /// Cleanup to be done if the generator is dropped at this suspend point. |
| drop: Option<BasicBlock>, |
| }, |
| |
| /// Indicates the end of the dropping of a generator. |
| GeneratorDrop, |
| |
| /// A block where control flow only ever takes one real path, but borrowck |
| /// needs to be more conservative. |
| FalseEdge { |
| /// The target normal control flow will take. |
| real_target: BasicBlock, |
| /// A block control flow could conceptually jump to, but won't in |
| /// practice. |
| imaginary_target: BasicBlock, |
| }, |
| /// A terminator for blocks that only take one path in reality, but where we |
| /// reserve the right to unwind in borrowck, even if it won't happen in practice. |
| /// This can arise in infinite loops with no function calls for example. |
| FalseUnwind { |
| /// The target normal control flow will take. |
| real_target: BasicBlock, |
| /// The imaginary cleanup block link. This particular path will never be taken |
| /// in practice, but in order to avoid fragility we want to always |
| /// consider it in borrowck. We don't want to accept programs which |
| /// pass borrowck only when `panic=abort` or some assertions are disabled |
| /// due to release vs. debug mode builds. This needs to be an `Option` because |
| /// of the `remove_noop_landing_pads` and `no_landing_pads` passes. |
| unwind: Option<BasicBlock>, |
| }, |
| |
| /// Block ends with an inline assembly block. This is a terminator since |
| /// inline assembly is allowed to diverge. |
| InlineAsm { |
| /// The template for the inline assembly, with placeholders. |
| template: &'tcx [InlineAsmTemplatePiece], |
| |
| /// The operands for the inline assembly, as `Operand`s or `Place`s. |
| operands: Vec<InlineAsmOperand<'tcx>>, |
| |
| /// Miscellaneous options for the inline assembly. |
| options: InlineAsmOptions, |
| |
| /// Source spans for each line of the inline assembly code. These are |
| /// used to map assembler errors back to the line in the source code. |
| line_spans: &'tcx [Span], |
| |
| /// Destination block after the inline assembly returns, unless it is |
| /// diverging (InlineAsmOptions::NORETURN). |
| destination: Option<BasicBlock>, |
| }, |
| } |
| #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)] |
| pub struct Terminator<'tcx> { |
| pub source_info: SourceInfo, |
| pub kind: TerminatorKind<'tcx>, |
| } |
| |
| impl<'tcx> Terminator<'tcx> { |
| pub fn successors(&self) -> Successors<'_> { |
| self.kind.successors() |
| } |
| |
| pub fn successors_mut(&mut self) -> SuccessorsMut<'_> { |
| self.kind.successors_mut() |
| } |
| |
| pub fn unwind(&self) -> Option<&Option<BasicBlock>> { |
| self.kind.unwind() |
| } |
| |
| pub fn unwind_mut(&mut self) -> Option<&mut Option<BasicBlock>> { |
| self.kind.unwind_mut() |
| } |
| } |
| |
| impl<'tcx> TerminatorKind<'tcx> { |
| pub fn if_( |
| tcx: TyCtxt<'tcx>, |
| cond: Operand<'tcx>, |
| t: BasicBlock, |
| f: BasicBlock, |
| ) -> TerminatorKind<'tcx> { |
| TerminatorKind::SwitchInt { |
| discr: cond, |
| switch_ty: tcx.types.bool, |
| targets: SwitchTargets::static_if(0, f, t), |
| } |
| } |
| |
| pub fn successors(&self) -> Successors<'_> { |
| use self::TerminatorKind::*; |
| match *self { |
| Resume |
| | Abort |
| | GeneratorDrop |
| | Return |
| | Unreachable |
| | Call { destination: None, cleanup: None, .. } |
| | InlineAsm { destination: None, .. } => None.into_iter().chain(&[]), |
| Goto { target: ref t } |
| | Call { destination: None, cleanup: Some(ref t), .. } |
| | Call { destination: Some((_, ref t)), cleanup: None, .. } |
| | Yield { resume: ref t, drop: None, .. } |
| | DropAndReplace { target: ref t, unwind: None, .. } |
| | Drop { target: ref t, unwind: None, .. } |
| | Assert { target: ref t, cleanup: None, .. } |
| | FalseUnwind { real_target: ref t, unwind: None } |
| | InlineAsm { destination: Some(ref t), .. } => Some(t).into_iter().chain(&[]), |
| Call { destination: Some((_, ref t)), cleanup: Some(ref u), .. } |
| | Yield { resume: ref t, drop: Some(ref u), .. } |
| | DropAndReplace { target: ref t, unwind: Some(ref u), .. } |
| | Drop { target: ref t, unwind: Some(ref u), .. } |
| | Assert { target: ref t, cleanup: Some(ref u), .. } |
| | FalseUnwind { real_target: ref t, unwind: Some(ref u) } => { |
| Some(t).into_iter().chain(slice::from_ref(u)) |
| } |
| SwitchInt { ref targets, .. } => None.into_iter().chain(&targets.targets[..]), |
| FalseEdge { ref real_target, ref imaginary_target } => { |
| Some(real_target).into_iter().chain(slice::from_ref(imaginary_target)) |
| } |
| } |
| } |
| |
| pub fn successors_mut(&mut self) -> SuccessorsMut<'_> { |
| use self::TerminatorKind::*; |
| match *self { |
| Resume |
| | Abort |
| | GeneratorDrop |
| | Return |
| | Unreachable |
| | Call { destination: None, cleanup: None, .. } |
| | InlineAsm { destination: None, .. } => None.into_iter().chain(&mut []), |
| Goto { target: ref mut t } |
| | Call { destination: None, cleanup: Some(ref mut t), .. } |
| | Call { destination: Some((_, ref mut t)), cleanup: None, .. } |
| | Yield { resume: ref mut t, drop: None, .. } |
| | DropAndReplace { target: ref mut t, unwind: None, .. } |
| | Drop { target: ref mut t, unwind: None, .. } |
| | Assert { target: ref mut t, cleanup: None, .. } |
| | FalseUnwind { real_target: ref mut t, unwind: None } |
| | InlineAsm { destination: Some(ref mut t), .. } => Some(t).into_iter().chain(&mut []), |
| Call { destination: Some((_, ref mut t)), cleanup: Some(ref mut u), .. } |
| | Yield { resume: ref mut t, drop: Some(ref mut u), .. } |
| | DropAndReplace { target: ref mut t, unwind: Some(ref mut u), .. } |
| | Drop { target: ref mut t, unwind: Some(ref mut u), .. } |
| | Assert { target: ref mut t, cleanup: Some(ref mut u), .. } |
| | FalseUnwind { real_target: ref mut t, unwind: Some(ref mut u) } => { |
| Some(t).into_iter().chain(slice::from_mut(u)) |
| } |
| SwitchInt { ref mut targets, .. } => None.into_iter().chain(&mut targets.targets[..]), |
| FalseEdge { ref mut real_target, ref mut imaginary_target } => { |
| Some(real_target).into_iter().chain(slice::from_mut(imaginary_target)) |
| } |
| } |
| } |
| |
| pub fn unwind(&self) -> Option<&Option<BasicBlock>> { |
| match *self { |
| TerminatorKind::Goto { .. } |
| | TerminatorKind::Resume |
| | TerminatorKind::Abort |
| | TerminatorKind::Return |
| | TerminatorKind::Unreachable |
| | TerminatorKind::GeneratorDrop |
| | TerminatorKind::Yield { .. } |
| | TerminatorKind::SwitchInt { .. } |
| | TerminatorKind::FalseEdge { .. } |
| | TerminatorKind::InlineAsm { .. } => None, |
| TerminatorKind::Call { cleanup: ref unwind, .. } |
| | TerminatorKind::Assert { cleanup: ref unwind, .. } |
| | TerminatorKind::DropAndReplace { ref unwind, .. } |
| | TerminatorKind::Drop { ref unwind, .. } |
| | TerminatorKind::FalseUnwind { ref unwind, .. } => Some(unwind), |
| } |
| } |
| |
| pub fn unwind_mut(&mut self) -> Option<&mut Option<BasicBlock>> { |
| match *self { |
| TerminatorKind::Goto { .. } |
| | TerminatorKind::Resume |
| | TerminatorKind::Abort |
| | TerminatorKind::Return |
| | TerminatorKind::Unreachable |
| | TerminatorKind::GeneratorDrop |
| | TerminatorKind::Yield { .. } |
| | TerminatorKind::SwitchInt { .. } |
| | TerminatorKind::FalseEdge { .. } |
| | TerminatorKind::InlineAsm { .. } => None, |
| TerminatorKind::Call { cleanup: ref mut unwind, .. } |
| | TerminatorKind::Assert { cleanup: ref mut unwind, .. } |
| | TerminatorKind::DropAndReplace { ref mut unwind, .. } |
| | TerminatorKind::Drop { ref mut unwind, .. } |
| | TerminatorKind::FalseUnwind { ref mut unwind, .. } => Some(unwind), |
| } |
| } |
| } |
| |
| impl<'tcx> Debug for TerminatorKind<'tcx> { |
| fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { |
| self.fmt_head(fmt)?; |
| let successor_count = self.successors().count(); |
| let labels = self.fmt_successor_labels(); |
| assert_eq!(successor_count, labels.len()); |
| |
| match successor_count { |
| 0 => Ok(()), |
| |
| 1 => write!(fmt, " -> {:?}", self.successors().next().unwrap()), |
| |
| _ => { |
| write!(fmt, " -> [")?; |
| for (i, target) in self.successors().enumerate() { |
| if i > 0 { |
| write!(fmt, ", ")?; |
| } |
| write!(fmt, "{}: {:?}", labels[i], target)?; |
| } |
| write!(fmt, "]") |
| } |
| } |
| } |
| } |
| |
| impl<'tcx> TerminatorKind<'tcx> { |
| /// Writes the "head" part of the terminator; that is, its name and the data it uses to pick the |
| /// successor basic block, if any. The only information not included is the list of possible |
| /// successors, which may be rendered differently between the text and the graphviz format. |
| pub fn fmt_head<W: Write>(&self, fmt: &mut W) -> fmt::Result { |
| use self::TerminatorKind::*; |
| match self { |
| Goto { .. } => write!(fmt, "goto"), |
| SwitchInt { discr, .. } => write!(fmt, "switchInt({:?})", discr), |
| Return => write!(fmt, "return"), |
| GeneratorDrop => write!(fmt, "generator_drop"), |
| Resume => write!(fmt, "resume"), |
| Abort => write!(fmt, "abort"), |
| Yield { value, resume_arg, .. } => write!(fmt, "{:?} = yield({:?})", resume_arg, value), |
| Unreachable => write!(fmt, "unreachable"), |
| Drop { place, .. } => write!(fmt, "drop({:?})", place), |
| DropAndReplace { place, value, .. } => { |
| write!(fmt, "replace({:?} <- {:?})", place, value) |
| } |
| Call { func, args, destination, .. } => { |
| if let Some((destination, _)) = destination { |
| write!(fmt, "{:?} = ", destination)?; |
| } |
| write!(fmt, "{:?}(", func)?; |
| for (index, arg) in args.iter().enumerate() { |
| if index > 0 { |
| write!(fmt, ", ")?; |
| } |
| write!(fmt, "{:?}", arg)?; |
| } |
| write!(fmt, ")") |
| } |
| Assert { cond, expected, msg, .. } => { |
| write!(fmt, "assert(")?; |
| if !expected { |
| write!(fmt, "!")?; |
| } |
| write!(fmt, "{:?}, ", cond)?; |
| msg.fmt_assert_args(fmt)?; |
| write!(fmt, ")") |
| } |
| FalseEdge { .. } => write!(fmt, "falseEdge"), |
| FalseUnwind { .. } => write!(fmt, "falseUnwind"), |
| InlineAsm { template, ref operands, options, .. } => { |
| write!(fmt, "asm!(\"{}\"", InlineAsmTemplatePiece::to_string(template))?; |
| for op in operands { |
| write!(fmt, ", ")?; |
| let print_late = |&late| if late { "late" } else { "" }; |
| match op { |
| InlineAsmOperand::In { reg, value } => { |
| write!(fmt, "in({}) {:?}", reg, value)?; |
| } |
| InlineAsmOperand::Out { reg, late, place: Some(place) } => { |
| write!(fmt, "{}out({}) {:?}", print_late(late), reg, place)?; |
| } |
| InlineAsmOperand::Out { reg, late, place: None } => { |
| write!(fmt, "{}out({}) _", print_late(late), reg)?; |
| } |
| InlineAsmOperand::InOut { |
| reg, |
| late, |
| in_value, |
| out_place: Some(out_place), |
| } => { |
| write!( |
| fmt, |
| "in{}out({}) {:?} => {:?}", |
| print_late(late), |
| reg, |
| in_value, |
| out_place |
| )?; |
| } |
| InlineAsmOperand::InOut { reg, late, in_value, out_place: None } => { |
| write!(fmt, "in{}out({}) {:?} => _", print_late(late), reg, in_value)?; |
| } |
| InlineAsmOperand::Const { value } => { |
| write!(fmt, "const {:?}", value)?; |
| } |
| InlineAsmOperand::SymFn { value } => { |
| write!(fmt, "sym_fn {:?}", value)?; |
| } |
| InlineAsmOperand::SymStatic { def_id } => { |
| write!(fmt, "sym_static {:?}", def_id)?; |
| } |
| } |
| } |
| write!(fmt, ", options({:?}))", options) |
| } |
| } |
| } |
| |
| /// Returns the list of labels for the edges to the successor basic blocks. |
| pub fn fmt_successor_labels(&self) -> Vec<Cow<'static, str>> { |
| use self::TerminatorKind::*; |
| match *self { |
| Return | Resume | Abort | Unreachable | GeneratorDrop => vec![], |
| Goto { .. } => vec!["".into()], |
| SwitchInt { ref targets, switch_ty, .. } => ty::tls::with(|tcx| { |
| let param_env = ty::ParamEnv::empty(); |
| let switch_ty = tcx.lift(switch_ty).unwrap(); |
| let size = tcx.layout_of(param_env.and(switch_ty)).unwrap().size; |
| targets |
| .values |
| .iter() |
| .map(|&u| { |
| ty::Const::from_scalar(tcx, Scalar::from_uint(u, size), switch_ty) |
| .to_string() |
| .into() |
| }) |
| .chain(iter::once("otherwise".into())) |
| .collect() |
| }), |
| Call { destination: Some(_), cleanup: Some(_), .. } => { |
| vec!["return".into(), "unwind".into()] |
| } |
| Call { destination: Some(_), cleanup: None, .. } => vec!["return".into()], |
| Call { destination: None, cleanup: Some(_), .. } => vec!["unwind".into()], |
| Call { destination: None, cleanup: None, .. } => vec![], |
| Yield { drop: Some(_), .. } => vec!["resume".into(), "drop".into()], |
| Yield { drop: None, .. } => vec!["resume".into()], |
| DropAndReplace { unwind: None, .. } | Drop { unwind: None, .. } => { |
| vec!["return".into()] |
| } |
| DropAndReplace { unwind: Some(_), .. } | Drop { unwind: Some(_), .. } => { |
| vec!["return".into(), "unwind".into()] |
| } |
| Assert { cleanup: None, .. } => vec!["".into()], |
| Assert { .. } => vec!["success".into(), "unwind".into()], |
| FalseEdge { .. } => vec!["real".into(), "imaginary".into()], |
| FalseUnwind { unwind: Some(_), .. } => vec!["real".into(), "cleanup".into()], |
| FalseUnwind { unwind: None, .. } => vec!["real".into()], |
| InlineAsm { destination: Some(_), .. } => vec!["".into()], |
| InlineAsm { destination: None, .. } => vec![], |
| } |
| } |
| } |
