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Rollup merge of #66789 - eddyb:mir-source-scope-local-data, r=oli-obk

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rustc: move mir::SourceScopeLocalData to a field of SourceScopeData.

By having one `ClearCrossCrate<SourceScopeLocalData>` for each scope, as opposed to a single `ClearCrossCrate` for all the `SourceScopeLocalData`s, we can represent the fact that some scopes have `SourceScopeLocalData` associated with them, and some don't.

This is useful when doing MIR inlining across crates, because the `ClearCrossCrate` will be `Clear` for the cross-crate MIR scopes and `Set` for the local ones.

Also see https://github.com/rust-lang/rust/pull/66203#issuecomment-555589574 for some context around this approach.

Fixes #51314.
This commit is contained in:
Mazdak Farrokhzad 2019-12-02 04:09:00 +01:00 • committed by GitHub
commit fd09fad064
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GPG key ID: 4AEE18F83AFDEB23
11 changed files with 103 additions and 130 deletions
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17
src/librustc/mir/mod.rs
View file

@ -104,10 +104,6 @@ pub struct Body<'tcx> {
/// and used for debuginfo. Indexed by a `SourceScope`.
pub source_scopes: IndexVec<SourceScope, SourceScopeData>,
/// Crate-local information for each source scope, that can't (and
/// needn't) be tracked across crates.
pub source_scope_local_data: ClearCrossCrate<IndexVec<SourceScope, SourceScopeLocalData>>,
/// The yield type of the function, if it is a generator.
pub yield_ty: Option<Ty<'tcx>>,
@ -167,7 +163,6 @@ impl<'tcx> Body<'tcx> {
pub fn new(
basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
source_scopes: IndexVec<SourceScope, SourceScopeData>,
source_scope_local_data: ClearCrossCrate<IndexVec<SourceScope, SourceScopeLocalData>>,
local_decls: LocalDecls<'tcx>,
user_type_annotations: CanonicalUserTypeAnnotations<'tcx>,
arg_count: usize,
@ -188,7 +183,6 @@ impl<'tcx> Body<'tcx> {
phase: MirPhase::Build,
basic_blocks,
source_scopes,
source_scope_local_data,
yield_ty: None,
generator_drop: None,
generator_layout: None,
@ -435,6 +429,13 @@ pub enum ClearCrossCrate<T> {
}
impl<T> ClearCrossCrate<T> {
pub fn as_ref(&'a self) -> ClearCrossCrate<&'a T> {
match self {
ClearCrossCrate::Clear => ClearCrossCrate::Clear,
ClearCrossCrate::Set(v) => ClearCrossCrate::Set(v),
}
}
pub fn assert_crate_local(self) -> T {
match self {
ClearCrossCrate::Clear => bug!("unwrapping cross-crate data"),
@ -2027,6 +2028,10 @@ rustc_index::newtype_index! {
pub struct SourceScopeData {
pub span: Span,
pub parent_scope: Option<SourceScope>,
/// Crate-local information for this source scope, that can't (and
/// needn't) be tracked across crates.
pub local_data: ClearCrossCrate<SourceScopeLocalData>,
}
#[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]

1
src/librustc/mir/visit.rs
View file

@ -317,6 +317,7 @@ macro_rules! make_mir_visitor {
let SourceScopeData {
span,
parent_scope,
local_data: _,
} = scope_data;
self.visit_span(span);

15
src/librustc_mir/borrow_check/mod.rs
View file

@ -300,11 +300,10 @@ fn do_mir_borrowck<'a, 'tcx>(
let mut initial_diag =
mbcx.report_conflicting_borrow(location, (&place, span), bk, &borrow);
let lint_root = if let ClearCrossCrate::Set(ref vsi) = mbcx.body.source_scope_local_data {
let scope = mbcx.body.source_info(location).scope;
vsi[scope].lint_root
} else {
id
let lint_root = match &mbcx.body.source_scopes[scope].local_data {
ClearCrossCrate::Set(data) => data.lint_root,
_ => id,
};
// Span and message don't matter; we overwrite them below anyway
@ -338,8 +337,11 @@ fn do_mir_borrowck<'a, 'tcx>(
debug!("mbcx.used_mut: {:?}", mbcx.used_mut);
let used_mut = mbcx.used_mut;
for local in mbcx.body.mut_vars_and_args_iter().filter(|local| !used_mut.contains(local)) {
if let ClearCrossCrate::Set(ref vsi) = mbcx.body.source_scope_local_data {
let local_decl = &mbcx.body.local_decls[local];
let lint_root = match &mbcx.body.source_scopes[local_decl.source_info.scope].local_data {
ClearCrossCrate::Set(data) => data.lint_root,
_ => continue,
};
// Skip over locals that begin with an underscore or have no name
match mbcx.local_names[local] {
@ -358,7 +360,7 @@ fn do_mir_borrowck<'a, 'tcx>(
let mut_span = tcx.sess.source_map().span_until_non_whitespace(span);
tcx.struct_span_lint_hir(
UNUSED_MUT,
vsi[local_decl.source_info.scope].lint_root,
lint_root,
span,
"variable does not need to be mutable",
)
@ -370,7 +372,6 @@ fn do_mir_borrowck<'a, 'tcx>(
)
.emit();
}
}
// Buffer any move errors that we collected and de-duplicated.
for (_, (_, diag)) in mbcx.move_error_reported {

9
src/librustc_mir/build/mod.rs
View file

@ -309,7 +309,6 @@ struct Builder<'a, 'tcx> {
/// The vector of all scopes that we have created thus far;
/// we track this for debuginfo later.
source_scopes: IndexVec<SourceScope, SourceScopeData>,
source_scope_local_data: IndexVec<SourceScope, SourceScopeLocalData>,
source_scope: SourceScope,
/// The guard-context: each time we build the guard expression for
@ -704,7 +703,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
block_context: BlockContext::new(),
source_scopes: IndexVec::new(),
source_scope: OUTERMOST_SOURCE_SCOPE,
source_scope_local_data: IndexVec::new(),
guard_context: vec![],
push_unsafe_count: 0,
unpushed_unsafe: safety,
@ -741,7 +739,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
Body::new(
self.cfg.basic_blocks,
self.source_scopes,
ClearCrossCrate::Set(self.source_scope_local_data),
self.local_decls,
self.canonical_user_type_annotations,
self.arg_count,
@ -942,7 +939,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
self.hir.root_lint_level
);
let parent_root = tcx.maybe_lint_level_root_bounded(
self.source_scope_local_data[original_source_scope].lint_root,
self.source_scopes[original_source_scope]
.local_data
.as_ref()
.assert_crate_local()
.lint_root,
self.hir.root_lint_level,
);
if current_root != parent_root {

23
src/librustc_mir/build/scope.rs
View file

@ -436,7 +436,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
// We estimate the true lint roots here to avoid creating a lot of source scopes.
let parent_root = tcx.maybe_lint_level_root_bounded(
self.source_scope_local_data[source_scope].lint_root,
self.source_scopes[source_scope]
.local_data
.as_ref()
.assert_crate_local()
.lint_root,
self.hir.root_lint_level,
);
let current_root = tcx.maybe_lint_level_root_bounded(
@ -654,23 +658,22 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
let parent = self.source_scope;
debug!("new_source_scope({:?}, {:?}, {:?}) - parent({:?})={:?}",
span, lint_level, safety,
parent, self.source_scope_local_data.get(parent));
let scope = self.source_scopes.push(SourceScopeData {
span,
parent_scope: Some(parent),
});
parent, self.source_scopes.get(parent));
let scope_local_data = SourceScopeLocalData {
lint_root: if let LintLevel::Explicit(lint_root) = lint_level {
lint_root
} else {
self.source_scope_local_data[parent].lint_root
self.source_scopes[parent].local_data.as_ref().assert_crate_local().lint_root
},
safety: safety.unwrap_or_else(|| {
self.source_scope_local_data[parent].safety
self.source_scopes[parent].local_data.as_ref().assert_crate_local().safety
})
};
self.source_scope_local_data.push(scope_local_data);
scope
self.source_scopes.push(SourceScopeData {
span,
parent_scope: Some(parent),
local_data: ClearCrossCrate::Set(scope_local_data),
})
}
/// Given a span and the current source scope, make a SourceInfo.

4
src/librustc_mir/interpret/eval_context.rs
View file

@ -849,8 +849,8 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
} else {
block.terminator().source_info
};
match body.source_scope_local_data {
mir::ClearCrossCrate::Set(ref ivs) => Some(ivs[source_info.scope].lint_root),
match &body.source_scopes[source_info.scope].local_data {
mir::ClearCrossCrate::Set(data) => Some(data.lint_root),
mir::ClearCrossCrate::Clear => None,
}
});

19
src/librustc_mir/shim.rs
View file

@ -198,9 +198,6 @@ fn build_drop_shim<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, ty: Option<Ty<'tcx>>)
let mut body = new_body(
blocks,
IndexVec::from_elem_n(
SourceScopeData { span, parent_scope: None }, 1
),
local_decls_for_sig(&sig, span),
sig.inputs().len(),
span);
@ -244,15 +241,16 @@ fn build_drop_shim<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, ty: Option<Ty<'tcx>>)
fn new_body<'tcx>(
basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
source_scopes: IndexVec<SourceScope, SourceScopeData>,
local_decls: IndexVec<Local, LocalDecl<'tcx>>,
arg_count: usize,
span: Span,
) -> Body<'tcx> {
Body::new(
basic_blocks,
source_scopes,
ClearCrossCrate::Clear,
IndexVec::from_elem_n(
SourceScopeData { span, parent_scope: None, local_data: ClearCrossCrate::Clear },
1,
),
local_decls,
IndexVec::new(),
arg_count,
@ -380,9 +378,6 @@ impl CloneShimBuilder<'tcx> {
fn into_mir(self) -> Body<'tcx> {
new_body(
self.blocks,
IndexVec::from_elem_n(
SourceScopeData { span: self.span, parent_scope: None }, 1
),
self.local_decls,
self.sig.inputs().len(),
self.span,
@ -836,9 +831,6 @@ fn build_call_shim<'tcx>(
let mut body = new_body(
blocks,
IndexVec::from_elem_n(
SourceScopeData { span, parent_scope: None }, 1
),
local_decls,
sig.inputs().len(),
span,
@ -919,9 +911,6 @@ pub fn build_adt_ctor(tcx: TyCtxt<'_>, ctor_id: DefId) -> &Body<'_> {
let body = new_body(
IndexVec::from_elem_n(start_block, 1),
IndexVec::from_elem_n(
SourceScopeData { span, parent_scope: None }, 1
),
local_decls,
sig.inputs().len(),
span,

33
src/librustc_mir/transform/check_unsafety.rs
View file

@ -1,6 +1,4 @@
use rustc_data_structures::fx::FxHashSet;
use rustc_index::vec::IndexVec;
use rustc_data_structures::sync::Lrc;
use rustc::ty::query::Providers;
use rustc::ty::{self, TyCtxt};
@ -24,7 +22,6 @@ pub struct UnsafetyChecker<'a, 'tcx> {
body: &'a Body<'tcx>,
const_context: bool,
min_const_fn: bool,
source_scope_local_data: &'a IndexVec<SourceScope, SourceScopeLocalData>,
violations: Vec<UnsafetyViolation>,
source_info: SourceInfo,
tcx: TyCtxt<'tcx>,
@ -39,7 +36,6 @@ impl<'a, 'tcx> UnsafetyChecker<'a, 'tcx> {
const_context: bool,
min_const_fn: bool,
body: &'a Body<'tcx>,
source_scope_local_data: &'a IndexVec<SourceScope, SourceScopeLocalData>,
tcx: TyCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,
) -> Self {
@ -51,7 +47,6 @@ impl<'a, 'tcx> UnsafetyChecker<'a, 'tcx> {
body,
const_context,
min_const_fn,
source_scope_local_data,
violations: vec![],
source_info: SourceInfo {
span: body.span,
@ -219,8 +214,11 @@ impl<'a, 'tcx> Visitor<'tcx> for UnsafetyChecker<'a, 'tcx> {
if context.is_borrow() {
if util::is_disaligned(self.tcx, self.body, self.param_env, place) {
let source_info = self.source_info;
let lint_root =
self.source_scope_local_data[source_info.scope].lint_root;
let lint_root = self.body.source_scopes[source_info.scope]
.local_data
.as_ref()
.assert_crate_local()
.lint_root;
self.register_violations(&[UnsafetyViolation {
source_info,
description: Symbol::intern("borrow of packed field"),
@ -346,7 +344,11 @@ impl<'a, 'tcx> UnsafetyChecker<'a, 'tcx> {
fn register_violations(&mut self,
violations: &[UnsafetyViolation],
unsafe_blocks: &[(hir::HirId, bool)]) {
let safety = self.source_scope_local_data[self.source_info.scope].safety;
let safety = self.body.source_scopes[self.source_info.scope]
.local_data
.as_ref()
.assert_crate_local()
.safety;
let within_unsafe = match safety {
// `unsafe` blocks are required in safe code
Safety::Safe => {
@ -516,17 +518,6 @@ fn unsafety_check_result(tcx: TyCtxt<'_>, def_id: DefId) -> UnsafetyCheckResult
// `mir_built` force this.
let body = &tcx.mir_built(def_id).borrow();
let source_scope_local_data = match body.source_scope_local_data {
ClearCrossCrate::Set(ref data) => data,
ClearCrossCrate::Clear => {
debug!("unsafety_violations: {:?} - remote, skipping", def_id);
return UnsafetyCheckResult {
violations: Lrc::new([]),
unsafe_blocks: Lrc::new([])
}
}
};
let param_env = tcx.param_env(def_id);
let id = tcx.hir().as_local_hir_id(def_id).unwrap();
@ -536,9 +527,7 @@ fn unsafety_check_result(tcx: TyCtxt<'_>, def_id: DefId) -> UnsafetyCheckResult
hir::BodyOwnerKind::Const |
hir::BodyOwnerKind::Static(_) => (true, false),
};
let mut checker = UnsafetyChecker::new(
const_context, min_const_fn,
body, source_scope_local_data, tcx, param_env);
let mut checker = UnsafetyChecker::new(const_context, min_const_fn, body, tcx, param_env);
checker.visit_body(body);
check_unused_unsafe(tcx, def_id, &checker.used_unsafe, &mut checker.inherited_blocks);

52
src/librustc_mir/transform/const_prop.rs
View file

@ -9,7 +9,7 @@ use rustc::hir::def_id::DefId;
use rustc::mir::{
AggregateKind, Constant, Location, Place, PlaceBase, Body, Operand, Rvalue, Local, UnOp,
StatementKind, Statement, LocalKind, TerminatorKind, Terminator, ClearCrossCrate, SourceInfo,
BinOp, SourceScope, SourceScopeLocalData, LocalDecl, BasicBlock, RETURN_PLACE,
BinOp, SourceScope, SourceScopeData, LocalDecl, BasicBlock, RETURN_PLACE,
};
use rustc::mir::visit::{
Visitor, PlaceContext, MutatingUseContext, MutVisitor, NonMutatingUseContext,
@ -74,17 +74,10 @@ impl<'tcx> MirPass<'tcx> for ConstProp {
trace!("ConstProp starting for {:?}", source.def_id());
// Steal some data we need from `body`.
let source_scope_local_data = std::mem::replace(
&mut body.source_scope_local_data,
ClearCrossCrate::Clear
);
let dummy_body =
&Body::new(
body.basic_blocks().clone(),
Default::default(),
ClearCrossCrate::Clear,
body.source_scopes.clone(),
body.local_decls.clone(),
Default::default(),
body.arg_count,
@ -101,19 +94,11 @@ impl<'tcx> MirPass<'tcx> for ConstProp {
let mut optimization_finder = ConstPropagator::new(
body,
dummy_body,
source_scope_local_data,
tcx,
source
);
optimization_finder.visit_body(body);
// put back the data we stole from `mir`
let source_scope_local_data = optimization_finder.release_stolen_data();
std::mem::replace(
&mut body.source_scope_local_data,
source_scope_local_data
);
trace!("ConstProp done for {:?}", source.def_id());
}
}
@ -267,7 +252,9 @@ struct ConstPropagator<'mir, 'tcx> {
source: MirSource<'tcx>,
can_const_prop: IndexVec<Local, bool>,
param_env: ParamEnv<'tcx>,
source_scope_local_data: ClearCrossCrate<IndexVec<SourceScope, SourceScopeLocalData>>,
// FIXME(eddyb) avoid cloning these two fields more than once,
// by accessing them through `ecx` instead.
source_scopes: IndexVec<SourceScope, SourceScopeData>,
local_decls: IndexVec<Local, LocalDecl<'tcx>>,
ret: Option<OpTy<'tcx, ()>>,
}
@ -299,7 +286,6 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
fn new(
body: &Body<'tcx>,
dummy_body: &'mir Body<'tcx>,
source_scope_local_data: ClearCrossCrate<IndexVec<SourceScope, SourceScopeLocalData>>,
tcx: TyCtxt<'tcx>,
source: MirSource<'tcx>,
) -> ConstPropagator<'mir, 'tcx> {
@ -337,17 +323,15 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
source,
param_env,
can_const_prop,
source_scope_local_data,
// FIXME(eddyb) avoid cloning these two fields more than once,
// by accessing them through `ecx` instead.
source_scopes: body.source_scopes.clone(),
//FIXME(wesleywiser) we can't steal this because `Visitor::super_visit_body()` needs it
local_decls: body.local_decls.clone(),
ret: ret.map(Into::into),
}
}
fn release_stolen_data(self) -> ClearCrossCrate<IndexVec<SourceScope, SourceScopeLocalData>> {
self.source_scope_local_data
}
fn get_const(&self, local: Local) -> Option<Const<'tcx>> {
if local == RETURN_PLACE {
// Try to read the return place as an immediate so that if it is representable as a
@ -377,14 +361,11 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
F: FnOnce(&mut Self) -> InterpResult<'tcx, T>,
{
self.ecx.tcx.span = source_info.span;
let lint_root = match self.source_scope_local_data {
ClearCrossCrate::Set(ref ivs) => {
//FIXME(#51314): remove this check
if source_info.scope.index() >= ivs.len() {
return None;
}
ivs[source_info.scope].lint_root
},
// FIXME(eddyb) move this to the `Panic(_)` error case, so that
// `f(self)` is always called, and that the only difference when the
// scope's `local_data` is missing, is that the lint isn't emitted.
let lint_root = match &self.source_scopes[source_info.scope].local_data {
ClearCrossCrate::Set(data) => data.lint_root,
ClearCrossCrate::Clear => return None,
};
let r = match f(self) {
@ -525,8 +506,8 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
let right_size = r.layout.size;
let r_bits = r.to_scalar().and_then(|r| r.to_bits(right_size));
if r_bits.ok().map_or(false, |b| b >= left_bits as u128) {
let source_scope_local_data = match self.source_scope_local_data {
ClearCrossCrate::Set(ref data) => data,
let lint_root = match &self.source_scopes[source_info.scope].local_data {
ClearCrossCrate::Set(data) => data.lint_root,
ClearCrossCrate::Clear => return None,
};
let dir = if *op == BinOp::Shr {
@ -534,10 +515,9 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
} else {
"left"
};
let hir_id = source_scope_local_data[source_info.scope].lint_root;
self.tcx.lint_hir(
::rustc::lint::builtin::EXCEEDING_BITSHIFTS,
hir_id,
lint_root,
span,
&format!("attempt to shift {} with overflow", dir));
return None;

5
src/librustc_mir/transform/inline.rs
View file

@ -391,9 +391,14 @@ impl Inliner<'tcx> {
for mut scope in callee_body.source_scopes.iter().cloned() {
if scope.parent_scope.is_none() {
scope.parent_scope = Some(callsite.location.scope);
// FIXME(eddyb) is this really needed?
// (also note that it's always overwritten below)
scope.span = callee_body.span;
}
// FIXME(eddyb) this doesn't seem right at all.
// The inlined source scopes should probably be annotated as
// such, but also contain all of the original information.
scope.span = callsite.location.span;
let idx = caller_body.source_scopes.push(scope);

1
src/librustc_mir/transform/promote_consts.rs
View file

@ -1081,7 +1081,6 @@ pub fn promote_candidates<'tcx>(
// FIXME: maybe try to filter this to avoid blowing up
// memory usage?
body.source_scopes.clone(),
body.source_scope_local_data.clone(),
initial_locals,
IndexVec::new(),
0,