diff options
Diffstat (limited to 'compiler/rustc_middle/src/mir/syntax.rs')
| -rw-r--r-- | compiler/rustc_middle/src/mir/syntax.rs | 41 |
1 files changed, 26 insertions, 15 deletions
diff --git a/compiler/rustc_middle/src/mir/syntax.rs b/compiler/rustc_middle/src/mir/syntax.rs index cc35e6106e2..c2a12bb3b66 100644 --- a/compiler/rustc_middle/src/mir/syntax.rs +++ b/compiler/rustc_middle/src/mir/syntax.rs @@ -515,14 +515,14 @@ pub struct CopyNonOverlapping<'tcx> { /// /// A note on unwinding: Panics may occur during the execution of some terminators. Depending on the /// `-C panic` flag, this may either cause the program to abort or the call stack to unwind. Such -/// terminators have a `cleanup: Option<BasicBlock>` field on them. If stack unwinding occurs, then -/// once the current function is reached, execution continues at the given basic block, if any. If -/// `cleanup` is `None` then no cleanup is performed, and the stack continues unwinding. This is -/// equivalent to the execution of a `Resume` terminator. +/// terminators have a `unwind: UnwindAction` field on them. If stack unwinding occurs, then +/// once the current function is reached, an action will be taken based on the `unwind` field. +/// If the action is `Cleanup`, then the execution continues at the given basic block. If the +/// action is `Continue` then no cleanup is performed, and the stack continues unwinding. /// -/// The basic block pointed to by a `cleanup` field must have its `cleanup` flag set. `cleanup` -/// basic blocks have a couple restrictions: -/// 1. All `cleanup` fields in them must be `None`. +/// The basic block pointed to by a `Cleanup` unwind action must have its `cleanup` flag set. +/// `cleanup` basic blocks have a couple restrictions: +/// 1. All `unwind` fields in them must be `UnwindAction::Continue`. /// 2. `Return` terminators are not allowed in them. `Abort` and `Unwind` terminators are. /// 3. All other basic blocks (in the current body) that are reachable from `cleanup` basic blocks /// must also be `cleanup`. This is a part of the type system and checked statically, so it is @@ -604,7 +604,7 @@ pub enum TerminatorKind<'tcx> { /// > The drop glue is executed if, among all statements executed within this `Body`, an assignment to /// > the place or one of its "parents" occurred more recently than a move out of it. This does not /// > consider indirect assignments. - Drop { place: Place<'tcx>, target: BasicBlock, unwind: Option<BasicBlock> }, + Drop { place: Place<'tcx>, target: BasicBlock, unwind: UnwindAction }, /// Roughly speaking, evaluates the `func` operand and the arguments, and starts execution of /// the referred to function. The operand types must match the argument types of the function. @@ -628,8 +628,8 @@ pub enum TerminatorKind<'tcx> { destination: Place<'tcx>, /// Where to go after this call returns. If none, the call necessarily diverges. target: Option<BasicBlock>, - /// Cleanups to be done if the call unwinds. - cleanup: Option<BasicBlock>, + /// Action to be taken if the call unwinds. + unwind: UnwindAction, /// `true` if this is from a call in HIR rather than from an overloaded /// operator. True for overloaded function call. from_hir_call: bool, @@ -654,7 +654,7 @@ pub enum TerminatorKind<'tcx> { expected: bool, msg: AssertMessage<'tcx>, target: BasicBlock, - cleanup: Option<BasicBlock>, + unwind: UnwindAction, }, /// Marks a suspend point. @@ -720,9 +720,10 @@ pub enum TerminatorKind<'tcx> { /// 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 + /// due to release vs. debug mode builds. + /// This field does not necessary have to be `UnwindAction::Cleanup` because /// of the `remove_noop_landing_pads` and `abort_unwinding_calls` passes. - unwind: Option<BasicBlock>, + unwind: UnwindAction, }, /// Block ends with an inline assembly block. This is a terminator since @@ -745,12 +746,22 @@ pub enum TerminatorKind<'tcx> { /// diverging (InlineAsmOptions::NORETURN). destination: Option<BasicBlock>, - /// Cleanup to be done if the inline assembly unwinds. This is present + /// Action to be taken if the inline assembly unwinds. This is present /// if and only if InlineAsmOptions::MAY_UNWIND is set. - cleanup: Option<BasicBlock>, + unwind: UnwindAction, }, } +/// Action to be taken when a stack unwind happens. +#[derive(Copy, Clone, Debug, PartialEq, TyEncodable, TyDecodable, Hash, HashStable)] +#[derive(TypeFoldable, TypeVisitable)] +pub enum UnwindAction { + // No action is to be taken. Continue unwinding. + Continue, + // Cleanups to be done. + Cleanup(BasicBlock), +} + /// Information about an assertion failure. #[derive(Clone, TyEncodable, TyDecodable, Hash, HashStable, PartialEq, TypeFoldable, TypeVisitable)] pub enum AssertKind<O> { |