bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

moves terminator types to sub module

Browse source
This commit is contained in:
root 2020-06-26 19:07:36 +00:00
parent 7750c3d46b
commit 15e81beb47
2 changed files with 519 additions and 494 deletions
Download patch file Download diff file Expand all files Collapse all files

506
src/librustc_middle/mir/mod.rs
View file

@ -21,7 +21,6 @@ use rustc_target::abi::VariantIdx;
use polonius_engine::Atom; use polonius_engine::Atom;
pub use rustc_ast::ast::Mutability; pub use rustc_ast::ast::Mutability;
use rustc_ast::ast::{InlineAsmOptions, InlineAsmTemplatePiece};
use rustc_data_structures::fx::FxHashSet; use rustc_data_structures::fx::FxHashSet;
use rustc_data_structures::graph::dominators::{dominators, Dominators}; use rustc_data_structures::graph::dominators::{dominators, Dominators};
use rustc_data_structures::graph::{self, GraphSuccessors}; use rustc_data_structures::graph::{self, GraphSuccessors};
@ -47,6 +46,8 @@ pub mod mono;
mod predecessors; mod predecessors;
mod query; mod query;
pub mod tcx; pub mod tcx;
pub mod terminator;
pub use terminator::*;
pub mod traversal; pub mod traversal;
mod type_foldable; mod type_foldable;
pub mod visit; pub mod visit;
@ -298,7 +299,11 @@ impl<'tcx> Body<'tcx> {
pub fn temps_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a { pub fn temps_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
(self.arg_count + 1..self.local_decls.len()).filter_map(move |index| { (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
let local = Local::new(index); let local = Local::new(index);
if self.local_decls[local].is_user_variable() { None } else { Some(local) } if self.local_decls[local].is_user_variable() {
None
} else {
Some(local)
}
}) })
} }
@ -1059,191 +1064,6 @@ pub struct BasicBlockData<'tcx> {
pub is_cleanup: bool, pub is_cleanup: bool,
} }
#[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
pub struct Terminator<'tcx> {
pub source_info: SourceInfo,
pub kind: TerminatorKind<'tcx>,
}
#[derive(Clone, RustcEncodable, RustcDecodable, 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>,
/// Possible values. The locations to branch to in each case
/// are found in the corresponding indices from the `targets` vector.
values: Cow<'tcx, [u128]>,
/// 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: Vec<BasicBlock>,
},
/// 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
/// }
/// ```
DropAndReplace {
place: Place<'tcx>,
value: Operand<'tcx>,
target: BasicBlock,
unwind: Option<BasicBlock>,
},
/// Block ends with a call of a converging 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>,
},
}
/// Information about an assertion failure. /// Information about an assertion failure.
#[derive(Clone, RustcEncodable, RustcDecodable, HashStable, PartialEq)] #[derive(Clone, RustcEncodable, RustcDecodable, HashStable, PartialEq)]
pub enum AssertKind<O> { pub enum AssertKind<O> {
@ -1292,149 +1112,6 @@ pub type Successors<'a> =
pub type SuccessorsMut<'a> = pub type SuccessorsMut<'a> =
iter::Chain<option::IntoIter<&'a mut BasicBlock>, slice::IterMut<'a, BasicBlock>>; iter::Chain<option::IntoIter<&'a mut BasicBlock>, slice::IterMut<'a, BasicBlock>>;
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> {
static BOOL_SWITCH_FALSE: &[u128] = &[0];
TerminatorKind::SwitchInt {
discr: cond,
switch_ty: tcx.types.bool,
values: From::from(BOOL_SWITCH_FALSE),
targets: vec![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[..]),
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[..]),
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> BasicBlockData<'tcx> { impl<'tcx> BasicBlockData<'tcx> {
pub fn new(terminator: Option<Terminator<'tcx>>) -> BasicBlockData<'tcx> { pub fn new(terminator: Option<Terminator<'tcx>>) -> BasicBlockData<'tcx> {
BasicBlockData { statements: vec![], terminator, is_cleanup: false } BasicBlockData { statements: vec![], terminator, is_cleanup: false }
@ -1513,7 +1190,11 @@ impl<'tcx> BasicBlockData<'tcx> {
} }
pub fn visitable(&self, index: usize) -> &dyn MirVisitable<'tcx> { pub fn visitable(&self, index: usize) -> &dyn MirVisitable<'tcx> {
if index < self.statements.len() { &self.statements[index] } else { &self.terminator } if index < self.statements.len() {
&self.statements[index]
} else {
&self.terminator
}
} }
} }
@ -1641,169 +1322,6 @@ impl<O: fmt::Debug> fmt::Debug for AssertKind<O> {
} }
} }
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 values, 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;
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![],
}
}
}
/////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////
// Statements // Statements

507
src/librustc_middle/mir/terminator/mod.rs Normal file
View file

@ -0,0 +1,507 @@
use crate::mir::interpret::Scalar;
use crate::ty::{self, Ty, TyCtxt};
use rustc_ast::ast::{InlineAsmOptions, InlineAsmTemplatePiece};
use super::{
AssertMessage, BasicBlock, InlineAsmOperand, Operand, Place, SourceInfo, Successors,
SuccessorsMut,
};
pub use rustc_ast::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(Clone, RustcEncodable, RustcDecodable, 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>,
/// Possible values. The locations to branch to in each case
/// are found in the corresponding indices from the `targets` vector.
values: Cow<'tcx, [u128]>,
/// 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: Vec<BasicBlock>,
},
/// 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
/// }
/// ```
DropAndReplace {
place: Place<'tcx>,
value: Operand<'tcx>,
target: BasicBlock,
unwind: Option<BasicBlock>,
},
/// Block ends with a call of a converging 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, RustcEncodable, RustcDecodable, 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> {
static BOOL_SWITCH_FALSE: &[u128] = &[0];
TerminatorKind::SwitchInt {
discr: cond,
switch_ty: tcx.types.bool,
values: From::from(BOOL_SWITCH_FALSE),
targets: vec![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[..]),
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[..]),
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 values, 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;
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![],
}
}
}