diff options
Diffstat (limited to 'compiler/rustc_middle/src/mir/terminator.rs')
| -rw-r--r-- | compiler/rustc_middle/src/mir/terminator.rs | 421 |
1 files changed, 215 insertions, 206 deletions
diff --git a/compiler/rustc_middle/src/mir/terminator.rs b/compiler/rustc_middle/src/mir/terminator.rs index 1f878d23b..02aab4a89 100644 --- a/compiler/rustc_middle/src/mir/terminator.rs +++ b/compiler/rustc_middle/src/mir/terminator.rs @@ -1,38 +1,16 @@ +/// Functionality for terminators and helper types that appear in terminators. +use rustc_hir::LangItem; use smallvec::SmallVec; use super::{BasicBlock, InlineAsmOperand, Operand, SourceInfo, TerminatorKind, UnwindAction}; -use rustc_ast::InlineAsmTemplatePiece; pub use rustc_ast::Mutability; use rustc_macros::HashStable; -use std::borrow::Cow; -use std::fmt::{self, Debug, Formatter, Write}; use std::iter; use std::slice; pub use super::query::*; use super::*; -#[derive(Debug, Clone, TyEncodable, TyDecodable, Hash, 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. /// @@ -100,6 +78,202 @@ impl<'a> Iterator for SwitchTargetsIter<'a> { impl<'a> ExactSizeIterator for SwitchTargetsIter<'a> {} +impl UnwindAction { + fn cleanup_block(self) -> Option<BasicBlock> { + match self { + UnwindAction::Cleanup(bb) => Some(bb), + UnwindAction::Continue | UnwindAction::Unreachable | UnwindAction::Terminate(_) => None, + } + } +} + +impl UnwindTerminateReason { + pub fn as_str(self) -> &'static str { + // Keep this in sync with the messages in `core/src/panicking.rs`. + match self { + UnwindTerminateReason::Abi => "panic in a function that cannot unwind", + UnwindTerminateReason::InCleanup => "panic in a destructor during cleanup", + } + } + + /// A short representation of this used for MIR printing. + pub fn as_short_str(self) -> &'static str { + match self { + UnwindTerminateReason::Abi => "abi", + UnwindTerminateReason::InCleanup => "cleanup", + } + } + + pub fn lang_item(self) -> LangItem { + match self { + UnwindTerminateReason::Abi => LangItem::PanicCannotUnwind, + UnwindTerminateReason::InCleanup => LangItem::PanicInCleanup, + } + } +} + +impl<O> AssertKind<O> { + /// Returns true if this an overflow checking assertion controlled by -C overflow-checks. + pub fn is_optional_overflow_check(&self) -> bool { + use AssertKind::*; + use BinOp::*; + matches!(self, OverflowNeg(..) | Overflow(Add | Sub | Mul | Shl | Shr, ..)) + } + + /// Get the message that is printed at runtime when this assertion fails. + /// + /// The caller is expected to handle `BoundsCheck` and `MisalignedPointerDereference` by + /// invoking the appropriate lang item (panic_bounds_check/panic_misaligned_pointer_dereference) + /// instead of printing a static message. + pub fn description(&self) -> &'static str { + use AssertKind::*; + match self { + Overflow(BinOp::Add, _, _) => "attempt to add with overflow", + Overflow(BinOp::Sub, _, _) => "attempt to subtract with overflow", + Overflow(BinOp::Mul, _, _) => "attempt to multiply with overflow", + Overflow(BinOp::Div, _, _) => "attempt to divide with overflow", + Overflow(BinOp::Rem, _, _) => "attempt to calculate the remainder with overflow", + OverflowNeg(_) => "attempt to negate with overflow", + Overflow(BinOp::Shr, _, _) => "attempt to shift right with overflow", + Overflow(BinOp::Shl, _, _) => "attempt to shift left with overflow", + Overflow(op, _, _) => bug!("{:?} cannot overflow", op), + DivisionByZero(_) => "attempt to divide by zero", + RemainderByZero(_) => "attempt to calculate the remainder with a divisor of zero", + ResumedAfterReturn(GeneratorKind::Gen) => "generator resumed after completion", + ResumedAfterReturn(GeneratorKind::Async(_)) => "`async fn` resumed after completion", + ResumedAfterPanic(GeneratorKind::Gen) => "generator resumed after panicking", + ResumedAfterPanic(GeneratorKind::Async(_)) => "`async fn` resumed after panicking", + BoundsCheck { .. } | MisalignedPointerDereference { .. } => { + bug!("Unexpected AssertKind") + } + } + } + + /// Format the message arguments for the `assert(cond, msg..)` terminator in MIR printing. + /// + /// Needs to be kept in sync with the run-time behavior (which is defined by + /// `AssertKind::description` and the lang items mentioned in its docs). + /// Note that we deliberately show more details here than we do at runtime, such as the actual + /// numbers that overflowed -- it is much easier to do so here than at runtime. + pub fn fmt_assert_args<W: fmt::Write>(&self, f: &mut W) -> fmt::Result + where + O: Debug, + { + use AssertKind::*; + match self { + BoundsCheck { ref len, ref index } => write!( + f, + "\"index out of bounds: the length is {{}} but the index is {{}}\", {len:?}, {index:?}" + ), + + OverflowNeg(op) => { + write!(f, "\"attempt to negate `{{}}`, which would overflow\", {op:?}") + } + DivisionByZero(op) => write!(f, "\"attempt to divide `{{}}` by zero\", {op:?}"), + RemainderByZero(op) => write!( + f, + "\"attempt to calculate the remainder of `{{}}` with a divisor of zero\", {op:?}" + ), + Overflow(BinOp::Add, l, r) => write!( + f, + "\"attempt to compute `{{}} + {{}}`, which would overflow\", {l:?}, {r:?}" + ), + Overflow(BinOp::Sub, l, r) => write!( + f, + "\"attempt to compute `{{}} - {{}}`, which would overflow\", {l:?}, {r:?}" + ), + Overflow(BinOp::Mul, l, r) => write!( + f, + "\"attempt to compute `{{}} * {{}}`, which would overflow\", {l:?}, {r:?}" + ), + Overflow(BinOp::Div, l, r) => write!( + f, + "\"attempt to compute `{{}} / {{}}`, which would overflow\", {l:?}, {r:?}" + ), + Overflow(BinOp::Rem, l, r) => write!( + f, + "\"attempt to compute the remainder of `{{}} % {{}}`, which would overflow\", {l:?}, {r:?}" + ), + Overflow(BinOp::Shr, _, r) => { + write!(f, "\"attempt to shift right by `{{}}`, which would overflow\", {r:?}") + } + Overflow(BinOp::Shl, _, r) => { + write!(f, "\"attempt to shift left by `{{}}`, which would overflow\", {r:?}") + } + MisalignedPointerDereference { required, found } => { + write!( + f, + "\"misaligned pointer dereference: address must be a multiple of {{}} but is {{}}\", {required:?}, {found:?}" + ) + } + _ => write!(f, "\"{}\"", self.description()), + } + } + + /// Format the diagnostic message for use in a lint (e.g. when the assertion fails during const-eval). + /// + /// Needs to be kept in sync with the run-time behavior (which is defined by + /// `AssertKind::description` and the lang items mentioned in its docs). + /// Note that we deliberately show more details here than we do at runtime, such as the actual + /// numbers that overflowed -- it is much easier to do so here than at runtime. + pub fn diagnostic_message(&self) -> DiagnosticMessage { + use crate::fluent_generated::*; + use AssertKind::*; + + match self { + BoundsCheck { .. } => middle_bounds_check, + Overflow(BinOp::Shl, _, _) => middle_assert_shl_overflow, + Overflow(BinOp::Shr, _, _) => middle_assert_shr_overflow, + Overflow(_, _, _) => middle_assert_op_overflow, + OverflowNeg(_) => middle_assert_overflow_neg, + DivisionByZero(_) => middle_assert_divide_by_zero, + RemainderByZero(_) => middle_assert_remainder_by_zero, + ResumedAfterReturn(GeneratorKind::Async(_)) => middle_assert_async_resume_after_return, + ResumedAfterReturn(GeneratorKind::Gen) => middle_assert_generator_resume_after_return, + ResumedAfterPanic(GeneratorKind::Async(_)) => middle_assert_async_resume_after_panic, + ResumedAfterPanic(GeneratorKind::Gen) => middle_assert_generator_resume_after_panic, + + MisalignedPointerDereference { .. } => middle_assert_misaligned_ptr_deref, + } + } + + pub fn add_args(self, adder: &mut dyn FnMut(Cow<'static, str>, DiagnosticArgValue<'static>)) + where + O: fmt::Debug, + { + use AssertKind::*; + + macro_rules! add { + ($name: expr, $value: expr) => { + adder($name.into(), $value.into_diagnostic_arg()); + }; + } + + match self { + BoundsCheck { len, index } => { + add!("len", format!("{len:?}")); + add!("index", format!("{index:?}")); + } + Overflow(BinOp::Shl | BinOp::Shr, _, val) + | DivisionByZero(val) + | RemainderByZero(val) + | OverflowNeg(val) => { + add!("val", format!("{val:#?}")); + } + Overflow(binop, left, right) => { + add!("op", binop.to_hir_binop().as_str()); + add!("left", format!("{left:#?}")); + add!("right", format!("{right:#?}")); + } + ResumedAfterReturn(_) | ResumedAfterPanic(_) => {} + MisalignedPointerDereference { required, found } => { + add!("required", format!("{required:#?}")); + add!("found", format!("{found:#?}")); + } + } + } +} + #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)] pub struct Terminator<'tcx> { pub source_info: SourceInfo, @@ -155,8 +329,8 @@ impl<'tcx> TerminatorKind<'tcx> { | InlineAsm { destination: Some(t), unwind: _, .. } => { Some(t).into_iter().chain((&[]).into_iter().copied()) } - Resume - | Terminate + UnwindResume + | UnwindTerminate(_) | GeneratorDrop | Return | Unreachable @@ -197,8 +371,8 @@ impl<'tcx> TerminatorKind<'tcx> { | InlineAsm { destination: Some(ref mut t), unwind: _, .. } => { Some(t).into_iter().chain(&mut []) } - Resume - | Terminate + UnwindResume + | UnwindTerminate(_) | GeneratorDrop | Return | Unreachable @@ -214,8 +388,8 @@ impl<'tcx> TerminatorKind<'tcx> { pub fn unwind(&self) -> Option<&UnwindAction> { match *self { TerminatorKind::Goto { .. } - | TerminatorKind::Resume - | TerminatorKind::Terminate + | TerminatorKind::UnwindResume + | TerminatorKind::UnwindTerminate(_) | TerminatorKind::Return | TerminatorKind::Unreachable | TerminatorKind::GeneratorDrop @@ -233,8 +407,8 @@ impl<'tcx> TerminatorKind<'tcx> { pub fn unwind_mut(&mut self) -> Option<&mut UnwindAction> { match *self { TerminatorKind::Goto { .. } - | TerminatorKind::Resume - | TerminatorKind::Terminate + | TerminatorKind::UnwindResume + | TerminatorKind::UnwindTerminate(_) | TerminatorKind::Return | TerminatorKind::Unreachable | TerminatorKind::GeneratorDrop @@ -264,174 +438,6 @@ impl<'tcx> TerminatorKind<'tcx> { } } -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()); - - let unwind = match self.unwind() { - // Not needed or included in successors - None | Some(UnwindAction::Cleanup(_)) => None, - Some(UnwindAction::Continue) => Some("unwind continue"), - Some(UnwindAction::Unreachable) => Some("unwind unreachable"), - Some(UnwindAction::Terminate) => Some("unwind terminate"), - }; - - match (successor_count, unwind) { - (0, None) => Ok(()), - (0, Some(unwind)) => write!(fmt, " -> {unwind}"), - (1, None) => 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)?; - } - if let Some(unwind) = unwind { - write!(fmt, ", {unwind}")?; - } - 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"), - Terminate => write!(fmt, "abort"), - Yield { value, resume_arg, .. } => write!(fmt, "{resume_arg:?} = yield({value:?})"), - Unreachable => write!(fmt, "unreachable"), - Drop { place, .. } => write!(fmt, "drop({place:?})"), - Call { func, args, 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 | Terminate | Unreachable | GeneratorDrop => vec![], - Goto { .. } => vec!["".into()], - SwitchInt { ref targets, .. } => targets - .values - .iter() - .map(|&u| Cow::Owned(u.to_string())) - .chain(iter::once("otherwise".into())) - .collect(), - Call { target: Some(_), unwind: UnwindAction::Cleanup(_), .. } => { - vec!["return".into(), "unwind".into()] - } - Call { target: Some(_), unwind: _, .. } => vec!["return".into()], - Call { target: None, unwind: UnwindAction::Cleanup(_), .. } => vec!["unwind".into()], - Call { target: None, unwind: _, .. } => vec![], - Yield { drop: Some(_), .. } => vec!["resume".into(), "drop".into()], - Yield { drop: None, .. } => vec!["resume".into()], - Drop { unwind: UnwindAction::Cleanup(_), .. } => vec!["return".into(), "unwind".into()], - Drop { unwind: _, .. } => vec!["return".into()], - Assert { unwind: UnwindAction::Cleanup(_), .. } => { - vec!["success".into(), "unwind".into()] - } - Assert { unwind: _, .. } => vec!["success".into()], - FalseEdge { .. } => vec!["real".into(), "imaginary".into()], - FalseUnwind { unwind: UnwindAction::Cleanup(_), .. } => { - vec!["real".into(), "unwind".into()] - } - FalseUnwind { unwind: _, .. } => vec!["real".into()], - InlineAsm { destination: Some(_), unwind: UnwindAction::Cleanup(_), .. } => { - vec!["return".into(), "unwind".into()] - } - InlineAsm { destination: Some(_), unwind: _, .. } => { - vec!["return".into()] - } - InlineAsm { destination: None, unwind: UnwindAction::Cleanup(_), .. } => { - vec!["unwind".into()] - } - InlineAsm { destination: None, unwind: _, .. } => vec![], - } - } -} - #[derive(Copy, Clone, Debug)] pub enum TerminatorEdges<'mir, 'tcx> { /// For terminators that have no successor, like `return`. @@ -443,7 +449,8 @@ pub enum TerminatorEdges<'mir, 'tcx> { /// Special action for `Yield`, `Call` and `InlineAsm` terminators. AssignOnReturn { return_: Option<BasicBlock>, - unwind: UnwindAction, + /// The cleanup block, if it exists. + cleanup: Option<BasicBlock>, place: CallReturnPlaces<'mir, 'tcx>, }, /// Special edge for `SwitchInt`. @@ -486,7 +493,9 @@ impl<'tcx> TerminatorKind<'tcx> { pub fn edges(&self) -> TerminatorEdges<'_, 'tcx> { use TerminatorKind::*; match *self { - Return | Resume | Terminate | GeneratorDrop | Unreachable => TerminatorEdges::None, + Return | UnwindResume | UnwindTerminate(_) | GeneratorDrop | Unreachable => { + TerminatorEdges::None + } Goto { target } => TerminatorEdges::Single(target), @@ -494,7 +503,7 @@ impl<'tcx> TerminatorKind<'tcx> { | Drop { target, unwind, place: _, replace: _ } | FalseUnwind { real_target: target, unwind } => match unwind { UnwindAction::Cleanup(unwind) => TerminatorEdges::Double(target, unwind), - UnwindAction::Continue | UnwindAction::Terminate | UnwindAction::Unreachable => { + UnwindAction::Continue | UnwindAction::Terminate(_) | UnwindAction::Unreachable => { TerminatorEdges::Single(target) } }, @@ -506,7 +515,7 @@ impl<'tcx> TerminatorKind<'tcx> { Yield { resume: target, drop, resume_arg, value: _ } => { TerminatorEdges::AssignOnReturn { return_: Some(target), - unwind: drop.map_or(UnwindAction::Terminate, UnwindAction::Cleanup), + cleanup: drop, place: CallReturnPlaces::Yield(resume_arg), } } @@ -514,7 +523,7 @@ impl<'tcx> TerminatorKind<'tcx> { Call { unwind, destination, target, func: _, args: _, fn_span: _, call_source: _ } => { TerminatorEdges::AssignOnReturn { return_: target, - unwind, + cleanup: unwind.cleanup_block(), place: CallReturnPlaces::Call(destination), } } @@ -528,7 +537,7 @@ impl<'tcx> TerminatorKind<'tcx> { unwind, } => TerminatorEdges::AssignOnReturn { return_: destination, - unwind, + cleanup: unwind.cleanup_block(), place: CallReturnPlaces::InlineAsm(operands), }, |