1274 lines
48 KiB
Rust
1274 lines
48 KiB
Rust
//! # The MIR Visitor
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//!
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//! ## Overview
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//!
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//! There are two visitors, one for immutable and one for mutable references,
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//! but both are generated by the following macro. The code is written according
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//! to the following conventions:
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//!
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//! - introduce a `visit_foo` and a `super_foo` method for every MIR type
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//! - `visit_foo`, by default, calls `super_foo`
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//! - `super_foo`, by default, destructures the `foo` and calls `visit_foo`
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//!
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//! This allows you as a user to override `visit_foo` for types are
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//! interested in, and invoke (within that method) call
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//! `self.super_foo` to get the default behavior. Just as in an OO
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//! language, you should never call `super` methods ordinarily except
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//! in that circumstance.
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//!
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//! For the most part, we do not destructure things external to the
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//! MIR, e.g., types, spans, etc, but simply visit them and stop. This
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//! avoids duplication with other visitors like `TypeFoldable`.
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//!
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//! ## Updating
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//!
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//! The code is written in a very deliberate style intended to minimize
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//! the chance of things being overlooked. You'll notice that we always
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//! use pattern matching to reference fields and we ensure that all
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//! matches are exhaustive.
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//!
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//! For example, the `super_basic_block_data` method begins like this:
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//!
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//! ```rust
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//! fn super_basic_block_data(&mut self,
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//! block: BasicBlock,
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//! data: & $($mutability)? BasicBlockData<'tcx>) {
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//! let BasicBlockData {
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//! statements,
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//! terminator,
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//! is_cleanup: _
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//! } = *data;
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//!
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//! for statement in statements {
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//! self.visit_statement(block, statement);
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//! }
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//!
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//! ...
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//! }
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//! ```
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//!
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//! Here we used `let BasicBlockData { <fields> } = *data` deliberately,
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//! rather than writing `data.statements` in the body. This is because if one
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//! adds a new field to `BasicBlockData`, one will be forced to revise this code,
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//! and hence one will (hopefully) invoke the correct visit methods (if any).
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//!
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//! For this to work, ALL MATCHES MUST BE EXHAUSTIVE IN FIELDS AND VARIANTS.
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//! That means you never write `..` to skip over fields, nor do you write `_`
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//! to skip over variants in a `match`.
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//!
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//! The only place that `_` is acceptable is to match a field (or
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//! variant argument) that does not require visiting, as in
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//! `is_cleanup` above.
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use crate::mir::*;
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use crate::ty::subst::SubstsRef;
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use crate::ty::{CanonicalUserTypeAnnotation, Ty};
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use rustc_span::Span;
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macro_rules! make_mir_visitor {
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($visitor_trait_name:ident, $($mutability:ident)?) => {
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pub trait $visitor_trait_name<'tcx> {
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// Override these, and call `self.super_xxx` to revert back to the
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// default behavior.
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fn visit_body(
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&mut self,
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body: &$($mutability)? Body<'tcx>,
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) {
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self.super_body(body);
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}
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fn visit_basic_block_data(&mut self,
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block: BasicBlock,
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data: & $($mutability)? BasicBlockData<'tcx>) {
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self.super_basic_block_data(block, data);
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}
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fn visit_source_scope_data(&mut self,
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scope_data: & $($mutability)? SourceScopeData<'tcx>) {
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self.super_source_scope_data(scope_data);
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}
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fn visit_statement(&mut self,
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statement: & $($mutability)? Statement<'tcx>,
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location: Location) {
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self.super_statement(statement, location);
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}
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fn visit_assign(&mut self,
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place: & $($mutability)? Place<'tcx>,
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rvalue: & $($mutability)? Rvalue<'tcx>,
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location: Location) {
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self.super_assign(place, rvalue, location);
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}
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fn visit_terminator(&mut self,
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terminator: & $($mutability)? Terminator<'tcx>,
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location: Location) {
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self.super_terminator(terminator, location);
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}
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fn visit_assert_message(&mut self,
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msg: & $($mutability)? AssertMessage<'tcx>,
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location: Location) {
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self.super_assert_message(msg, location);
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}
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fn visit_rvalue(&mut self,
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rvalue: & $($mutability)? Rvalue<'tcx>,
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location: Location) {
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self.super_rvalue(rvalue, location);
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}
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fn visit_operand(&mut self,
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operand: & $($mutability)? Operand<'tcx>,
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location: Location) {
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self.super_operand(operand, location);
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}
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fn visit_ascribe_user_ty(&mut self,
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place: & $($mutability)? Place<'tcx>,
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variance: & $($mutability)? ty::Variance,
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user_ty: & $($mutability)? UserTypeProjection,
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location: Location) {
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self.super_ascribe_user_ty(place, variance, user_ty, location);
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}
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fn visit_coverage(&mut self,
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coverage: & $($mutability)? Coverage,
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location: Location) {
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self.super_coverage(coverage, location);
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}
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fn visit_retag(&mut self,
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kind: & $($mutability)? RetagKind,
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place: & $($mutability)? Place<'tcx>,
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location: Location) {
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self.super_retag(kind, place, location);
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}
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fn visit_place(&mut self,
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place: & $($mutability)? Place<'tcx>,
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context: PlaceContext,
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location: Location) {
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self.super_place(place, context, location);
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}
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visit_place_fns!($($mutability)?);
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fn visit_constant(&mut self,
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constant: & $($mutability)? Constant<'tcx>,
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location: Location) {
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self.super_constant(constant, location);
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}
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fn visit_span(&mut self,
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span: & $($mutability)? Span) {
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self.super_span(span);
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}
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fn visit_source_info(&mut self,
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source_info: & $($mutability)? SourceInfo) {
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self.super_source_info(source_info);
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}
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fn visit_ty(&mut self,
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ty: $(& $mutability)? Ty<'tcx>,
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_: TyContext) {
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self.super_ty(ty);
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}
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fn visit_user_type_projection(
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&mut self,
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ty: & $($mutability)? UserTypeProjection,
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) {
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self.super_user_type_projection(ty);
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}
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fn visit_user_type_annotation(
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&mut self,
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index: UserTypeAnnotationIndex,
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ty: & $($mutability)? CanonicalUserTypeAnnotation<'tcx>,
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) {
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self.super_user_type_annotation(index, ty);
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}
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fn visit_region(&mut self,
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region: & $($mutability)? ty::Region<'tcx>,
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_: Location) {
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self.super_region(region);
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}
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fn visit_const(&mut self,
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constant: & $($mutability)? &'tcx ty::Const<'tcx>,
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_: Location) {
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self.super_const(constant);
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}
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fn visit_substs(&mut self,
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substs: & $($mutability)? SubstsRef<'tcx>,
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_: Location) {
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self.super_substs(substs);
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}
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fn visit_local_decl(&mut self,
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local: Local,
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local_decl: & $($mutability)? LocalDecl<'tcx>) {
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self.super_local_decl(local, local_decl);
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}
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fn visit_var_debug_info(&mut self,
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var_debug_info: & $($mutability)* VarDebugInfo<'tcx>) {
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self.super_var_debug_info(var_debug_info);
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}
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fn visit_local(&mut self,
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_local: & $($mutability)? Local,
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_context: PlaceContext,
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_location: Location) {
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}
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fn visit_source_scope(&mut self,
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scope: & $($mutability)? SourceScope) {
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self.super_source_scope(scope);
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}
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// The `super_xxx` methods comprise the default behavior and are
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// not meant to be overridden.
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fn super_body(
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&mut self,
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body: &$($mutability)? Body<'tcx>,
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) {
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let span = body.span;
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if let Some(gen) = &$($mutability)? body.generator {
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if let Some(yield_ty) = &$($mutability)? gen.yield_ty {
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self.visit_ty(
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yield_ty,
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TyContext::YieldTy(SourceInfo::outermost(span))
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);
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}
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}
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// for best performance, we want to use an iterator rather
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// than a for-loop, to avoid calling `body::Body::invalidate` for
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// each basic block.
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macro_rules! basic_blocks {
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(mut) => (body.basic_blocks_mut().iter_enumerated_mut());
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() => (body.basic_blocks().iter_enumerated());
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}
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for (bb, data) in basic_blocks!($($mutability)?) {
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self.visit_basic_block_data(bb, data);
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}
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for scope in &$($mutability)? body.source_scopes {
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self.visit_source_scope_data(scope);
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}
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self.visit_ty(
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&$($mutability)? body.return_ty(),
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TyContext::ReturnTy(SourceInfo::outermost(body.span))
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);
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for local in body.local_decls.indices() {
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self.visit_local_decl(local, & $($mutability)? body.local_decls[local]);
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}
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macro_rules! type_annotations {
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(mut) => (body.user_type_annotations.iter_enumerated_mut());
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() => (body.user_type_annotations.iter_enumerated());
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}
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for (index, annotation) in type_annotations!($($mutability)?) {
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self.visit_user_type_annotation(
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index, annotation
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);
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}
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for var_debug_info in &$($mutability)? body.var_debug_info {
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self.visit_var_debug_info(var_debug_info);
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}
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self.visit_span(&$($mutability)? body.span);
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for const_ in &$($mutability)? body.required_consts {
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let location = START_BLOCK.start_location();
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self.visit_constant(const_, location);
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}
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}
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fn super_basic_block_data(&mut self,
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block: BasicBlock,
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data: & $($mutability)? BasicBlockData<'tcx>) {
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let BasicBlockData {
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statements,
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terminator,
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is_cleanup: _
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} = data;
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let mut index = 0;
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for statement in statements {
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let location = Location { block, statement_index: index };
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self.visit_statement(statement, location);
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index += 1;
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}
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if let Some(terminator) = terminator {
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let location = Location { block, statement_index: index };
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self.visit_terminator(terminator, location);
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}
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}
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fn super_source_scope_data(
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&mut self,
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scope_data: & $($mutability)? SourceScopeData<'tcx>,
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) {
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let SourceScopeData {
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span,
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parent_scope,
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inlined,
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inlined_parent_scope,
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local_data: _,
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} = scope_data;
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self.visit_span(span);
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if let Some(parent_scope) = parent_scope {
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self.visit_source_scope(parent_scope);
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}
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if let Some((callee, callsite_span)) = inlined {
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let location = START_BLOCK.start_location();
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self.visit_span(callsite_span);
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let ty::Instance { def: callee_def, substs: callee_substs } = callee;
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match callee_def {
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ty::InstanceDef::Item(_def_id) => {}
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ty::InstanceDef::Intrinsic(_def_id) |
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ty::InstanceDef::VtableShim(_def_id) |
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ty::InstanceDef::ReifyShim(_def_id) |
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ty::InstanceDef::Virtual(_def_id, _) |
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ty::InstanceDef::ClosureOnceShim { call_once: _def_id } |
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ty::InstanceDef::DropGlue(_def_id, None) => {}
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ty::InstanceDef::FnPtrShim(_def_id, ty) |
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ty::InstanceDef::DropGlue(_def_id, Some(ty)) |
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ty::InstanceDef::CloneShim(_def_id, ty) => {
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// FIXME(eddyb) use a better `TyContext` here.
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self.visit_ty(ty, TyContext::Location(location));
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}
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}
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self.visit_substs(callee_substs, location);
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}
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if let Some(inlined_parent_scope) = inlined_parent_scope {
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self.visit_source_scope(inlined_parent_scope);
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}
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}
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fn super_statement(&mut self,
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statement: & $($mutability)? Statement<'tcx>,
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location: Location) {
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let Statement {
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source_info,
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kind,
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} = statement;
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self.visit_source_info(source_info);
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match kind {
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StatementKind::Assign(
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box(ref $($mutability)? place, ref $($mutability)? rvalue)
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) => {
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self.visit_assign(place, rvalue, location);
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}
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StatementKind::FakeRead(_, place) => {
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self.visit_place(
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place,
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PlaceContext::NonMutatingUse(NonMutatingUseContext::Inspect),
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location
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);
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}
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StatementKind::SetDiscriminant { place, .. } => {
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self.visit_place(
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place,
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PlaceContext::MutatingUse(MutatingUseContext::Store),
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location
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);
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}
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StatementKind::StorageLive(local) => {
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self.visit_local(
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local,
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PlaceContext::NonUse(NonUseContext::StorageLive),
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location
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);
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}
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StatementKind::StorageDead(local) => {
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self.visit_local(
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local,
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PlaceContext::NonUse(NonUseContext::StorageDead),
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location
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);
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}
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StatementKind::LlvmInlineAsm(asm) => {
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for output in & $($mutability)? asm.outputs[..] {
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self.visit_place(
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output,
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PlaceContext::MutatingUse(MutatingUseContext::AsmOutput),
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location
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);
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}
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for (span, input) in & $($mutability)? asm.inputs[..] {
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self.visit_span(span);
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self.visit_operand(input, location);
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}
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}
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StatementKind::Retag(kind, place) => {
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self.visit_retag(kind, place, location);
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}
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StatementKind::AscribeUserType(
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box(ref $($mutability)? place, ref $($mutability)? user_ty),
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variance
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) => {
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self.visit_ascribe_user_ty(place, variance, user_ty, location);
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}
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StatementKind::Coverage(coverage) => {
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self.visit_coverage(
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coverage,
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location
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)
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}
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StatementKind::CopyNonOverlapping(box crate::mir::CopyNonOverlapping{
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ref $($mutability)? src,
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ref $($mutability)? dst,
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ref $($mutability)? count,
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}) => {
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self.visit_operand(src, location);
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self.visit_operand(dst, location);
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self.visit_operand(count, location)
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}
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StatementKind::Nop => {}
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}
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}
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fn super_assign(&mut self,
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place: &$($mutability)? Place<'tcx>,
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rvalue: &$($mutability)? Rvalue<'tcx>,
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location: Location) {
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self.visit_place(
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place,
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PlaceContext::MutatingUse(MutatingUseContext::Store),
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location
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);
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self.visit_rvalue(rvalue, location);
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}
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fn super_terminator(&mut self,
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terminator: &$($mutability)? Terminator<'tcx>,
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location: Location) {
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let Terminator { source_info, kind } = terminator;
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self.visit_source_info(source_info);
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match kind {
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TerminatorKind::Goto { .. } |
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TerminatorKind::Resume |
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TerminatorKind::Abort |
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TerminatorKind::GeneratorDrop |
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TerminatorKind::Unreachable |
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TerminatorKind::FalseEdge { .. } |
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TerminatorKind::FalseUnwind { .. } => {
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}
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TerminatorKind::Return => {
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// `return` logically moves from the return place `_0`. Note that the place
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// cannot be changed by any visitor, though.
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let $($mutability)? local = RETURN_PLACE;
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self.visit_local(
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& $($mutability)? local,
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PlaceContext::NonMutatingUse(NonMutatingUseContext::Move),
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location,
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);
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assert_eq!(
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local,
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RETURN_PLACE,
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"`MutVisitor` tried to mutate return place of `return` terminator"
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);
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}
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TerminatorKind::SwitchInt {
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discr,
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switch_ty,
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targets: _
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} => {
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self.visit_operand(discr, location);
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self.visit_ty(switch_ty, TyContext::Location(location));
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}
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TerminatorKind::Drop {
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place,
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target: _,
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unwind: _,
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} => {
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self.visit_place(
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place,
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PlaceContext::MutatingUse(MutatingUseContext::Drop),
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location
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);
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}
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TerminatorKind::DropAndReplace {
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place,
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value,
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target: _,
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unwind: _,
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} => {
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self.visit_place(
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place,
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PlaceContext::MutatingUse(MutatingUseContext::Drop),
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location
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);
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self.visit_operand(value, location);
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}
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TerminatorKind::Call {
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func,
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args,
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destination,
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cleanup: _,
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from_hir_call: _,
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fn_span: _
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} => {
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self.visit_operand(func, location);
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for arg in args {
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self.visit_operand(arg, location);
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}
|
|
if let Some((destination, _)) = destination {
|
|
self.visit_place(
|
|
destination,
|
|
PlaceContext::MutatingUse(MutatingUseContext::Call),
|
|
location
|
|
);
|
|
}
|
|
}
|
|
|
|
TerminatorKind::Assert {
|
|
cond,
|
|
expected: _,
|
|
msg,
|
|
target: _,
|
|
cleanup: _,
|
|
} => {
|
|
self.visit_operand(cond, location);
|
|
self.visit_assert_message(msg, location);
|
|
}
|
|
|
|
TerminatorKind::Yield {
|
|
value,
|
|
resume: _,
|
|
resume_arg,
|
|
drop: _,
|
|
} => {
|
|
self.visit_operand(value, location);
|
|
self.visit_place(
|
|
resume_arg,
|
|
PlaceContext::MutatingUse(MutatingUseContext::Yield),
|
|
location,
|
|
);
|
|
}
|
|
|
|
TerminatorKind::InlineAsm {
|
|
template: _,
|
|
operands,
|
|
options: _,
|
|
line_spans: _,
|
|
destination: _,
|
|
} => {
|
|
for op in operands {
|
|
match op {
|
|
InlineAsmOperand::In { value, .. }
|
|
| InlineAsmOperand::Const { value } => {
|
|
self.visit_operand(value, location);
|
|
}
|
|
InlineAsmOperand::Out { place, .. } => {
|
|
if let Some(place) = place {
|
|
self.visit_place(
|
|
place,
|
|
PlaceContext::MutatingUse(MutatingUseContext::Store),
|
|
location,
|
|
);
|
|
}
|
|
}
|
|
InlineAsmOperand::InOut { in_value, out_place, .. } => {
|
|
self.visit_operand(in_value, location);
|
|
if let Some(out_place) = out_place {
|
|
self.visit_place(
|
|
out_place,
|
|
PlaceContext::MutatingUse(MutatingUseContext::Store),
|
|
location,
|
|
);
|
|
}
|
|
}
|
|
InlineAsmOperand::SymFn { value } => {
|
|
self.visit_constant(value, location);
|
|
}
|
|
InlineAsmOperand::SymStatic { def_id: _ } => {}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn super_assert_message(&mut self,
|
|
msg: & $($mutability)? AssertMessage<'tcx>,
|
|
location: Location) {
|
|
use crate::mir::AssertKind::*;
|
|
match msg {
|
|
BoundsCheck { len, index } => {
|
|
self.visit_operand(len, location);
|
|
self.visit_operand(index, location);
|
|
}
|
|
Overflow(_, l, r) => {
|
|
self.visit_operand(l, location);
|
|
self.visit_operand(r, location);
|
|
}
|
|
OverflowNeg(op) | DivisionByZero(op) | RemainderByZero(op) => {
|
|
self.visit_operand(op, location);
|
|
}
|
|
ResumedAfterReturn(_) | ResumedAfterPanic(_) => {
|
|
// Nothing to visit
|
|
}
|
|
}
|
|
}
|
|
|
|
fn super_rvalue(&mut self,
|
|
rvalue: & $($mutability)? Rvalue<'tcx>,
|
|
location: Location) {
|
|
match rvalue {
|
|
Rvalue::Use(operand) => {
|
|
self.visit_operand(operand, location);
|
|
}
|
|
|
|
Rvalue::Repeat(value, _) => {
|
|
self.visit_operand(value, location);
|
|
}
|
|
|
|
Rvalue::ThreadLocalRef(_) => {}
|
|
|
|
Rvalue::Ref(r, bk, path) => {
|
|
self.visit_region(r, location);
|
|
let ctx = match bk {
|
|
BorrowKind::Shared => PlaceContext::NonMutatingUse(
|
|
NonMutatingUseContext::SharedBorrow
|
|
),
|
|
BorrowKind::Shallow => PlaceContext::NonMutatingUse(
|
|
NonMutatingUseContext::ShallowBorrow
|
|
),
|
|
BorrowKind::Unique => PlaceContext::NonMutatingUse(
|
|
NonMutatingUseContext::UniqueBorrow
|
|
),
|
|
BorrowKind::Mut { .. } =>
|
|
PlaceContext::MutatingUse(MutatingUseContext::Borrow),
|
|
};
|
|
self.visit_place(path, ctx, location);
|
|
}
|
|
|
|
Rvalue::AddressOf(m, path) => {
|
|
let ctx = match m {
|
|
Mutability::Mut => PlaceContext::MutatingUse(
|
|
MutatingUseContext::AddressOf
|
|
),
|
|
Mutability::Not => PlaceContext::NonMutatingUse(
|
|
NonMutatingUseContext::AddressOf
|
|
),
|
|
};
|
|
self.visit_place(path, ctx, location);
|
|
}
|
|
|
|
Rvalue::Len(path) => {
|
|
self.visit_place(
|
|
path,
|
|
PlaceContext::NonMutatingUse(NonMutatingUseContext::Inspect),
|
|
location
|
|
);
|
|
}
|
|
|
|
Rvalue::Cast(_cast_kind, operand, ty) => {
|
|
self.visit_operand(operand, location);
|
|
self.visit_ty(ty, TyContext::Location(location));
|
|
}
|
|
|
|
Rvalue::BinaryOp(_bin_op, box(lhs, rhs))
|
|
| Rvalue::CheckedBinaryOp(_bin_op, box(lhs, rhs)) => {
|
|
self.visit_operand(lhs, location);
|
|
self.visit_operand(rhs, location);
|
|
}
|
|
|
|
Rvalue::UnaryOp(_un_op, op) => {
|
|
self.visit_operand(op, location);
|
|
}
|
|
|
|
Rvalue::Discriminant(place) => {
|
|
self.visit_place(
|
|
place,
|
|
PlaceContext::NonMutatingUse(NonMutatingUseContext::Inspect),
|
|
location
|
|
);
|
|
}
|
|
|
|
Rvalue::NullaryOp(_op, ty) => {
|
|
self.visit_ty(ty, TyContext::Location(location));
|
|
}
|
|
|
|
Rvalue::Aggregate(kind, operands) => {
|
|
let kind = &$($mutability)? **kind;
|
|
match kind {
|
|
AggregateKind::Array(ty) => {
|
|
self.visit_ty(ty, TyContext::Location(location));
|
|
}
|
|
AggregateKind::Tuple => {
|
|
}
|
|
AggregateKind::Adt(
|
|
_adt_def,
|
|
_variant_index,
|
|
substs,
|
|
_user_substs,
|
|
_active_field_index
|
|
) => {
|
|
self.visit_substs(substs, location);
|
|
}
|
|
AggregateKind::Closure(
|
|
_,
|
|
closure_substs
|
|
) => {
|
|
self.visit_substs(closure_substs, location);
|
|
}
|
|
AggregateKind::Generator(
|
|
_,
|
|
generator_substs,
|
|
_movability,
|
|
) => {
|
|
self.visit_substs(generator_substs, location);
|
|
}
|
|
}
|
|
|
|
for operand in operands {
|
|
self.visit_operand(operand, location);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn super_operand(&mut self,
|
|
operand: & $($mutability)? Operand<'tcx>,
|
|
location: Location) {
|
|
match operand {
|
|
Operand::Copy(place) => {
|
|
self.visit_place(
|
|
place,
|
|
PlaceContext::NonMutatingUse(NonMutatingUseContext::Copy),
|
|
location
|
|
);
|
|
}
|
|
Operand::Move(place) => {
|
|
self.visit_place(
|
|
place,
|
|
PlaceContext::NonMutatingUse(NonMutatingUseContext::Move),
|
|
location
|
|
);
|
|
}
|
|
Operand::Constant(constant) => {
|
|
self.visit_constant(constant, location);
|
|
}
|
|
}
|
|
}
|
|
|
|
fn super_ascribe_user_ty(&mut self,
|
|
place: & $($mutability)? Place<'tcx>,
|
|
_variance: & $($mutability)? ty::Variance,
|
|
user_ty: & $($mutability)? UserTypeProjection,
|
|
location: Location) {
|
|
self.visit_place(
|
|
place,
|
|
PlaceContext::NonUse(NonUseContext::AscribeUserTy),
|
|
location
|
|
);
|
|
self.visit_user_type_projection(user_ty);
|
|
}
|
|
|
|
fn super_coverage(&mut self,
|
|
_coverage: & $($mutability)? Coverage,
|
|
_location: Location) {
|
|
}
|
|
|
|
fn super_retag(&mut self,
|
|
_kind: & $($mutability)? RetagKind,
|
|
place: & $($mutability)? Place<'tcx>,
|
|
location: Location) {
|
|
self.visit_place(
|
|
place,
|
|
PlaceContext::MutatingUse(MutatingUseContext::Retag),
|
|
location,
|
|
);
|
|
}
|
|
|
|
fn super_local_decl(&mut self,
|
|
local: Local,
|
|
local_decl: & $($mutability)? LocalDecl<'tcx>) {
|
|
let LocalDecl {
|
|
mutability: _,
|
|
ty,
|
|
user_ty,
|
|
source_info,
|
|
internal: _,
|
|
local_info: _,
|
|
is_block_tail: _,
|
|
} = local_decl;
|
|
|
|
self.visit_ty(ty, TyContext::LocalDecl {
|
|
local,
|
|
source_info: *source_info,
|
|
});
|
|
if let Some(user_ty) = user_ty {
|
|
for (user_ty, _) in & $($mutability)? user_ty.contents {
|
|
self.visit_user_type_projection(user_ty);
|
|
}
|
|
}
|
|
self.visit_source_info(source_info);
|
|
}
|
|
|
|
fn super_var_debug_info(&mut self,
|
|
var_debug_info: & $($mutability)? VarDebugInfo<'tcx>) {
|
|
let VarDebugInfo {
|
|
name: _,
|
|
source_info,
|
|
value,
|
|
} = var_debug_info;
|
|
|
|
self.visit_source_info(source_info);
|
|
let location = START_BLOCK.start_location();
|
|
match value {
|
|
VarDebugInfoContents::Const(c) => self.visit_constant(c, location),
|
|
VarDebugInfoContents::Place(place) =>
|
|
self.visit_place(
|
|
place,
|
|
PlaceContext::NonUse(NonUseContext::VarDebugInfo),
|
|
location
|
|
),
|
|
}
|
|
}
|
|
|
|
fn super_source_scope(&mut self,
|
|
_scope: & $($mutability)? SourceScope) {
|
|
}
|
|
|
|
fn super_constant(&mut self,
|
|
constant: & $($mutability)? Constant<'tcx>,
|
|
location: Location) {
|
|
let Constant {
|
|
span,
|
|
user_ty,
|
|
literal,
|
|
} = constant;
|
|
|
|
self.visit_span(span);
|
|
drop(user_ty); // no visit method for this
|
|
match literal {
|
|
ConstantKind::Ty(ct) => self.visit_const(ct, location),
|
|
ConstantKind::Val(_, t) => self.visit_ty(t, TyContext::Location(location)),
|
|
}
|
|
}
|
|
|
|
fn super_span(&mut self, _span: & $($mutability)? Span) {
|
|
}
|
|
|
|
fn super_source_info(&mut self, source_info: & $($mutability)? SourceInfo) {
|
|
let SourceInfo {
|
|
span,
|
|
scope,
|
|
} = source_info;
|
|
|
|
self.visit_span(span);
|
|
self.visit_source_scope(scope);
|
|
}
|
|
|
|
fn super_user_type_projection(
|
|
&mut self,
|
|
_ty: & $($mutability)? UserTypeProjection,
|
|
) {
|
|
}
|
|
|
|
fn super_user_type_annotation(
|
|
&mut self,
|
|
_index: UserTypeAnnotationIndex,
|
|
ty: & $($mutability)? CanonicalUserTypeAnnotation<'tcx>,
|
|
) {
|
|
self.visit_span(& $($mutability)? ty.span);
|
|
self.visit_ty(& $($mutability)? ty.inferred_ty, TyContext::UserTy(ty.span));
|
|
}
|
|
|
|
fn super_ty(&mut self, _ty: $(& $mutability)? Ty<'tcx>) {
|
|
}
|
|
|
|
fn super_region(&mut self, _region: & $($mutability)? ty::Region<'tcx>) {
|
|
}
|
|
|
|
fn super_const(&mut self, _const: & $($mutability)? &'tcx ty::Const<'tcx>) {
|
|
}
|
|
|
|
fn super_substs(&mut self, _substs: & $($mutability)? SubstsRef<'tcx>) {
|
|
}
|
|
|
|
// Convenience methods
|
|
|
|
fn visit_location(
|
|
&mut self,
|
|
body: &$($mutability)? Body<'tcx>,
|
|
location: Location
|
|
) {
|
|
macro_rules! basic_blocks {
|
|
(mut) => (body.basic_blocks_mut());
|
|
() => (body.basic_blocks());
|
|
}
|
|
let basic_block = & $($mutability)? basic_blocks!($($mutability)?)[location.block];
|
|
if basic_block.statements.len() == location.statement_index {
|
|
if let Some(ref $($mutability)? terminator) = basic_block.terminator {
|
|
self.visit_terminator(terminator, location)
|
|
}
|
|
} else {
|
|
let statement = & $($mutability)?
|
|
basic_block.statements[location.statement_index];
|
|
self.visit_statement(statement, location)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
macro_rules! visit_place_fns {
|
|
(mut) => {
|
|
fn tcx<'a>(&'a self) -> TyCtxt<'tcx>;
|
|
|
|
fn super_place(
|
|
&mut self,
|
|
place: &mut Place<'tcx>,
|
|
context: PlaceContext,
|
|
location: Location,
|
|
) {
|
|
self.visit_local(&mut place.local, context, location);
|
|
|
|
if let Some(new_projection) = self.process_projection(&place.projection, location) {
|
|
place.projection = self.tcx().intern_place_elems(&new_projection);
|
|
}
|
|
}
|
|
|
|
fn process_projection(
|
|
&mut self,
|
|
projection: &'a [PlaceElem<'tcx>],
|
|
location: Location,
|
|
) -> Option<Vec<PlaceElem<'tcx>>> {
|
|
let mut projection = Cow::Borrowed(projection);
|
|
|
|
for i in 0..projection.len() {
|
|
if let Some(&elem) = projection.get(i) {
|
|
if let Some(elem) = self.process_projection_elem(elem, location) {
|
|
// This converts the borrowed projection into `Cow::Owned(_)` and returns a
|
|
// clone of the projection so we can mutate and reintern later.
|
|
let vec = projection.to_mut();
|
|
vec[i] = elem;
|
|
}
|
|
}
|
|
}
|
|
|
|
match projection {
|
|
Cow::Borrowed(_) => None,
|
|
Cow::Owned(vec) => Some(vec),
|
|
}
|
|
}
|
|
|
|
fn process_projection_elem(
|
|
&mut self,
|
|
elem: PlaceElem<'tcx>,
|
|
location: Location,
|
|
) -> Option<PlaceElem<'tcx>> {
|
|
match elem {
|
|
PlaceElem::Index(local) => {
|
|
let mut new_local = local;
|
|
self.visit_local(
|
|
&mut new_local,
|
|
PlaceContext::NonMutatingUse(NonMutatingUseContext::Copy),
|
|
location,
|
|
);
|
|
|
|
if new_local == local { None } else { Some(PlaceElem::Index(new_local)) }
|
|
}
|
|
PlaceElem::Deref
|
|
| PlaceElem::Field(..)
|
|
| PlaceElem::ConstantIndex { .. }
|
|
| PlaceElem::Subslice { .. }
|
|
| PlaceElem::Downcast(..) => None,
|
|
}
|
|
}
|
|
};
|
|
|
|
() => {
|
|
fn visit_projection(
|
|
&mut self,
|
|
place_ref: PlaceRef<'tcx>,
|
|
context: PlaceContext,
|
|
location: Location,
|
|
) {
|
|
self.super_projection(place_ref, context, location);
|
|
}
|
|
|
|
fn visit_projection_elem(
|
|
&mut self,
|
|
local: Local,
|
|
proj_base: &[PlaceElem<'tcx>],
|
|
elem: PlaceElem<'tcx>,
|
|
context: PlaceContext,
|
|
location: Location,
|
|
) {
|
|
self.super_projection_elem(local, proj_base, elem, context, location);
|
|
}
|
|
|
|
fn super_place(&mut self, place: &Place<'tcx>, context: PlaceContext, location: Location) {
|
|
let mut context = context;
|
|
|
|
if !place.projection.is_empty() {
|
|
if context.is_use() {
|
|
// ^ Only change the context if it is a real use, not a "use" in debuginfo.
|
|
context = if context.is_mutating_use() {
|
|
PlaceContext::MutatingUse(MutatingUseContext::Projection)
|
|
} else {
|
|
PlaceContext::NonMutatingUse(NonMutatingUseContext::Projection)
|
|
};
|
|
}
|
|
}
|
|
|
|
self.visit_local(&place.local, context, location);
|
|
|
|
self.visit_projection(place.as_ref(), context, location);
|
|
}
|
|
|
|
fn super_projection(
|
|
&mut self,
|
|
place_ref: PlaceRef<'tcx>,
|
|
context: PlaceContext,
|
|
location: Location,
|
|
) {
|
|
// FIXME: Use PlaceRef::iter_projections, once that exists.
|
|
let mut cursor = place_ref.projection;
|
|
while let &[ref proj_base @ .., elem] = cursor {
|
|
cursor = proj_base;
|
|
self.visit_projection_elem(place_ref.local, cursor, elem, context, location);
|
|
}
|
|
}
|
|
|
|
fn super_projection_elem(
|
|
&mut self,
|
|
_local: Local,
|
|
_proj_base: &[PlaceElem<'tcx>],
|
|
elem: PlaceElem<'tcx>,
|
|
_context: PlaceContext,
|
|
location: Location,
|
|
) {
|
|
match elem {
|
|
ProjectionElem::Field(_field, ty) => {
|
|
self.visit_ty(ty, TyContext::Location(location));
|
|
}
|
|
ProjectionElem::Index(local) => {
|
|
self.visit_local(
|
|
&local,
|
|
PlaceContext::NonMutatingUse(NonMutatingUseContext::Copy),
|
|
location,
|
|
);
|
|
}
|
|
ProjectionElem::Deref
|
|
| ProjectionElem::Subslice { from: _, to: _, from_end: _ }
|
|
| ProjectionElem::ConstantIndex { offset: _, min_length: _, from_end: _ }
|
|
| ProjectionElem::Downcast(_, _) => {}
|
|
}
|
|
}
|
|
};
|
|
}
|
|
|
|
make_mir_visitor!(Visitor,);
|
|
make_mir_visitor!(MutVisitor, mut);
|
|
|
|
pub trait MirVisitable<'tcx> {
|
|
fn apply(&self, location: Location, visitor: &mut dyn Visitor<'tcx>);
|
|
}
|
|
|
|
impl<'tcx> MirVisitable<'tcx> for Statement<'tcx> {
|
|
fn apply(&self, location: Location, visitor: &mut dyn Visitor<'tcx>) {
|
|
visitor.visit_statement(self, location)
|
|
}
|
|
}
|
|
|
|
impl<'tcx> MirVisitable<'tcx> for Terminator<'tcx> {
|
|
fn apply(&self, location: Location, visitor: &mut dyn Visitor<'tcx>) {
|
|
visitor.visit_terminator(self, location)
|
|
}
|
|
}
|
|
|
|
impl<'tcx> MirVisitable<'tcx> for Option<Terminator<'tcx>> {
|
|
fn apply(&self, location: Location, visitor: &mut dyn Visitor<'tcx>) {
|
|
visitor.visit_terminator(self.as_ref().unwrap(), location)
|
|
}
|
|
}
|
|
|
|
/// Extra information passed to `visit_ty` and friends to give context
|
|
/// about where the type etc appears.
|
|
#[derive(Debug)]
|
|
pub enum TyContext {
|
|
LocalDecl {
|
|
/// The index of the local variable we are visiting.
|
|
local: Local,
|
|
|
|
/// The source location where this local variable was declared.
|
|
source_info: SourceInfo,
|
|
},
|
|
|
|
/// The inferred type of a user type annotation.
|
|
UserTy(Span),
|
|
|
|
/// The return type of the function.
|
|
ReturnTy(SourceInfo),
|
|
|
|
YieldTy(SourceInfo),
|
|
|
|
/// A type found at some location.
|
|
Location(Location),
|
|
}
|
|
|
|
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
|
|
pub enum NonMutatingUseContext {
|
|
/// Being inspected in some way, like loading a len.
|
|
Inspect,
|
|
/// Consumed as part of an operand.
|
|
Copy,
|
|
/// Consumed as part of an operand.
|
|
Move,
|
|
/// Shared borrow.
|
|
SharedBorrow,
|
|
/// Shallow borrow.
|
|
ShallowBorrow,
|
|
/// Unique borrow.
|
|
UniqueBorrow,
|
|
/// AddressOf for *const pointer.
|
|
AddressOf,
|
|
/// Used as base for another place, e.g., `x` in `x.y`. Will not mutate the place.
|
|
/// For example, the projection `x.y` is not marked as a mutation in these cases:
|
|
///
|
|
/// z = x.y;
|
|
/// f(&x.y);
|
|
///
|
|
Projection,
|
|
}
|
|
|
|
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
|
|
pub enum MutatingUseContext {
|
|
/// Appears as LHS of an assignment.
|
|
Store,
|
|
/// Can often be treated as a `Store`, but needs to be separate because
|
|
/// ASM is allowed to read outputs as well, so a `Store`-`AsmOutput` sequence
|
|
/// cannot be simplified the way a `Store`-`Store` can be.
|
|
AsmOutput,
|
|
/// Destination of a call.
|
|
Call,
|
|
/// Destination of a yield.
|
|
Yield,
|
|
/// Being dropped.
|
|
Drop,
|
|
/// Mutable borrow.
|
|
Borrow,
|
|
/// AddressOf for *mut pointer.
|
|
AddressOf,
|
|
/// Used as base for another place, e.g., `x` in `x.y`. Could potentially mutate the place.
|
|
/// For example, the projection `x.y` is marked as a mutation in these cases:
|
|
///
|
|
/// x.y = ...;
|
|
/// f(&mut x.y);
|
|
///
|
|
Projection,
|
|
/// Retagging, a "Stacked Borrows" shadow state operation
|
|
Retag,
|
|
}
|
|
|
|
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
|
|
pub enum NonUseContext {
|
|
/// Starting a storage live range.
|
|
StorageLive,
|
|
/// Ending a storage live range.
|
|
StorageDead,
|
|
/// User type annotation assertions for NLL.
|
|
AscribeUserTy,
|
|
/// The data of an user variable, for debug info.
|
|
VarDebugInfo,
|
|
}
|
|
|
|
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
|
|
pub enum PlaceContext {
|
|
NonMutatingUse(NonMutatingUseContext),
|
|
MutatingUse(MutatingUseContext),
|
|
NonUse(NonUseContext),
|
|
}
|
|
|
|
impl PlaceContext {
|
|
/// Returns `true` if this place context represents a drop.
|
|
#[inline]
|
|
pub fn is_drop(&self) -> bool {
|
|
matches!(self, PlaceContext::MutatingUse(MutatingUseContext::Drop))
|
|
}
|
|
|
|
/// Returns `true` if this place context represents a borrow.
|
|
pub fn is_borrow(&self) -> bool {
|
|
matches!(
|
|
self,
|
|
PlaceContext::NonMutatingUse(
|
|
NonMutatingUseContext::SharedBorrow
|
|
| NonMutatingUseContext::ShallowBorrow
|
|
| NonMutatingUseContext::UniqueBorrow
|
|
) | PlaceContext::MutatingUse(MutatingUseContext::Borrow)
|
|
)
|
|
}
|
|
|
|
/// Returns `true` if this place context represents a storage live or storage dead marker.
|
|
#[inline]
|
|
pub fn is_storage_marker(&self) -> bool {
|
|
matches!(
|
|
self,
|
|
PlaceContext::NonUse(NonUseContext::StorageLive | NonUseContext::StorageDead)
|
|
)
|
|
}
|
|
|
|
/// Returns `true` if this place context represents a use that potentially changes the value.
|
|
#[inline]
|
|
pub fn is_mutating_use(&self) -> bool {
|
|
matches!(self, PlaceContext::MutatingUse(..))
|
|
}
|
|
|
|
/// Returns `true` if this place context represents a use that does not change the value.
|
|
#[inline]
|
|
pub fn is_nonmutating_use(&self) -> bool {
|
|
matches!(self, PlaceContext::NonMutatingUse(..))
|
|
}
|
|
|
|
/// Returns `true` if this place context represents a use.
|
|
#[inline]
|
|
pub fn is_use(&self) -> bool {
|
|
!matches!(self, PlaceContext::NonUse(..))
|
|
}
|
|
|
|
/// Returns `true` if this place context represents an assignment statement.
|
|
pub fn is_place_assignment(&self) -> bool {
|
|
matches!(
|
|
self,
|
|
PlaceContext::MutatingUse(
|
|
MutatingUseContext::Store
|
|
| MutatingUseContext::Call
|
|
| MutatingUseContext::AsmOutput,
|
|
)
|
|
)
|
|
}
|
|
}
|