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Auto merge of #71192 - oli-obk:eager_alloc_id_canonicalization, r=wes…
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…leywiser

Make TLS accesses explicit in MIR

r? @rust-lang/wg-mir-opt

cc @RalfJung @vakaras for miri thread locals

cc @bjorn3 for cranelift

fixes #70685
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bors committed Jun 1, 2020
2 parents b85e3fe + 0aa7f4d commit d3cba25
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Showing 31 changed files with 157 additions and 23 deletions.
1 change: 1 addition & 0 deletions src/librustc_codegen_llvm/common.rs
Original file line number Diff line number Diff line change
Expand Up @@ -259,6 +259,7 @@ impl ConstMethods<'tcx> for CodegenCx<'ll, 'tcx> {
GlobalAlloc::Function(fn_instance) => self.get_fn_addr(fn_instance),
GlobalAlloc::Static(def_id) => {
assert!(self.tcx.is_static(def_id));
assert!(!self.tcx.is_thread_local_static(def_id));
self.get_static(def_id)
}
};
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8 changes: 8 additions & 0 deletions src/librustc_codegen_ssa/mir/rvalue.rs
Original file line number Diff line number Diff line change
Expand Up @@ -522,6 +522,13 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
let operand = OperandRef { val: OperandValue::Immediate(val), layout: box_layout };
(bx, operand)
}
mir::Rvalue::ThreadLocalRef(def_id) => {
assert!(bx.cx().tcx().is_static(def_id));
let static_ = bx.get_static(def_id);
let layout = bx.layout_of(bx.cx().tcx().static_ptr_ty(def_id));
let operand = OperandRef::from_immediate_or_packed_pair(&mut bx, static_, layout);
(bx, operand)
}
mir::Rvalue::Use(ref operand) => {
let operand = self.codegen_operand(&mut bx, operand);
(bx, operand)
Expand Down Expand Up @@ -745,6 +752,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
mir::Rvalue::UnaryOp(..) |
mir::Rvalue::Discriminant(..) |
mir::Rvalue::NullaryOp(..) |
mir::Rvalue::ThreadLocalRef(_) |
mir::Rvalue::Use(..) => // (*)
true,
mir::Rvalue::Repeat(..) |
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3 changes: 3 additions & 0 deletions src/librustc_middle/mir/interpret/error.rs
Original file line number Diff line number Diff line change
Expand Up @@ -513,6 +513,8 @@ pub enum UnsupportedOpInfo {
//
/// Encountered raw bytes where we needed a pointer.
ReadBytesAsPointer,
/// Accessing thread local statics
ThreadLocalStatic(DefId),
}

impl fmt::Display for UnsupportedOpInfo {
Expand All @@ -526,6 +528,7 @@ impl fmt::Display for UnsupportedOpInfo {
NoMirFor(did) => write!(f, "no MIR body is available for {:?}", did),
ReadPointerAsBytes => write!(f, "unable to turn pointer into raw bytes",),
ReadBytesAsPointer => write!(f, "unable to turn bytes into a pointer"),
ThreadLocalStatic(did) => write!(f, "accessing thread local static {:?}", did),
}
}
}
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1 change: 1 addition & 0 deletions src/librustc_middle/mir/interpret/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -209,6 +209,7 @@ pub fn specialized_encode_alloc_id<'tcx, E: Encoder>(
fn_instance.encode(encoder)?;
}
GlobalAlloc::Static(did) => {
assert!(!tcx.is_thread_local_static(did));
// References to statics doesn't need to know about their allocations,
// just about its `DefId`.
AllocDiscriminant::Static.encode(encoder)?;
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14 changes: 13 additions & 1 deletion src/librustc_middle/mir/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2214,6 +2214,11 @@ pub enum Rvalue<'tcx> {
/// &x or &mut x
Ref(Region<'tcx>, BorrowKind, Place<'tcx>),

/// Accessing a thread local static. This is inherently a runtime operation, even if llvm
/// treats it as an access to a static. This `Rvalue` yields a reference to the thread local
/// static.
ThreadLocalRef(DefId),

/// Create a raw pointer to the given place
/// Can be generated by raw address of expressions (`&raw const x`),
/// or when casting a reference to a raw pointer.
Expand Down Expand Up @@ -2353,6 +2358,10 @@ impl<'tcx> Debug for Rvalue<'tcx> {
UnaryOp(ref op, ref a) => write!(fmt, "{:?}({:?})", op, a),
Discriminant(ref place) => write!(fmt, "discriminant({:?})", place),
NullaryOp(ref op, ref t) => write!(fmt, "{:?}({:?})", op, t),
ThreadLocalRef(did) => ty::tls::with(|tcx| {
let muta = tcx.static_mutability(did).unwrap().prefix_str();
write!(fmt, "&/*tls*/ {}{}", muta, tcx.def_path_str(did))
}),
Ref(region, borrow_kind, ref place) => {
let kind_str = match borrow_kind {
BorrowKind::Shared => "",
Expand Down Expand Up @@ -2506,7 +2515,10 @@ impl Constant<'tcx> {
pub fn check_static_ptr(&self, tcx: TyCtxt<'_>) -> Option<DefId> {
match self.literal.val.try_to_scalar() {
Some(Scalar::Ptr(ptr)) => match tcx.global_alloc(ptr.alloc_id) {
GlobalAlloc::Static(def_id) => Some(def_id),
GlobalAlloc::Static(def_id) => {
assert!(!tcx.is_thread_local_static(def_id));
Some(def_id)
}
_ => None,
},
_ => None,
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7 changes: 7 additions & 0 deletions src/librustc_middle/mir/tcx.rs
Original file line number Diff line number Diff line change
Expand Up @@ -151,6 +151,13 @@ impl<'tcx> Rvalue<'tcx> {
Rvalue::Repeat(ref operand, count) => {
tcx.mk_ty(ty::Array(operand.ty(local_decls, tcx), count))
}
Rvalue::ThreadLocalRef(did) => {
if tcx.is_mutable_static(did) {
tcx.mk_mut_ptr(tcx.type_of(did))
} else {
tcx.mk_imm_ref(tcx.lifetimes.re_static, tcx.type_of(did))
}
}
Rvalue::Ref(reg, bk, ref place) => {
let place_ty = place.ty(local_decls, tcx).ty;
tcx.mk_ref(reg, ty::TypeAndMut { ty: place_ty, mutbl: bk.to_mutbl_lossy() })
Expand Down
2 changes: 2 additions & 0 deletions src/librustc_middle/mir/type_foldable.rs
Original file line number Diff line number Diff line change
Expand Up @@ -177,6 +177,7 @@ impl<'tcx> TypeFoldable<'tcx> for Rvalue<'tcx> {
match *self {
Use(ref op) => Use(op.fold_with(folder)),
Repeat(ref op, len) => Repeat(op.fold_with(folder), len),
ThreadLocalRef(did) => ThreadLocalRef(did.fold_with(folder)),
Ref(region, bk, ref place) => {
Ref(region.fold_with(folder), bk, place.fold_with(folder))
}
Expand Down Expand Up @@ -220,6 +221,7 @@ impl<'tcx> TypeFoldable<'tcx> for Rvalue<'tcx> {
match *self {
Use(ref op) => op.visit_with(visitor),
Repeat(ref op, _) => op.visit_with(visitor),
ThreadLocalRef(did) => did.visit_with(visitor),
Ref(region, _, ref place) => region.visit_with(visitor) || place.visit_with(visitor),
AddressOf(_, ref place) => place.visit_with(visitor),
Len(ref place) => place.visit_with(visitor),
Expand Down
2 changes: 2 additions & 0 deletions src/librustc_middle/mir/visit.rs
Original file line number Diff line number Diff line change
Expand Up @@ -601,6 +601,8 @@ macro_rules! make_mir_visitor {
self.visit_operand(value, location);
}

Rvalue::ThreadLocalRef(_) => {}

Rvalue::Ref(r, bk, path) => {
self.visit_region(r, location);
let ctx = match bk {
Expand Down
2 changes: 2 additions & 0 deletions src/librustc_mir/borrow_check/invalidation.rs
Original file line number Diff line number Diff line change
Expand Up @@ -301,6 +301,8 @@ impl<'cx, 'tcx> InvalidationGenerator<'cx, 'tcx> {
self.access_place(location, place, access_kind, LocalMutationIsAllowed::No);
}

Rvalue::ThreadLocalRef(_) => {}

Rvalue::Use(ref operand)
| Rvalue::Repeat(ref operand, _)
| Rvalue::UnaryOp(_ /*un_op*/, ref operand)
Expand Down
2 changes: 2 additions & 0 deletions src/librustc_mir/borrow_check/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1296,6 +1296,8 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
);
}

Rvalue::ThreadLocalRef(_) => {}

Rvalue::Use(ref operand)
| Rvalue::Repeat(ref operand, _)
| Rvalue::UnaryOp(_ /*un_op*/, ref operand)
Expand Down
2 changes: 2 additions & 0 deletions src/librustc_mir/borrow_check/type_check/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2353,6 +2353,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
}

Rvalue::AddressOf(..)
| Rvalue::ThreadLocalRef(..)
| Rvalue::Use(..)
| Rvalue::Len(..)
| Rvalue::BinaryOp(..)
Expand All @@ -2368,6 +2369,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
fn rvalue_user_ty(&self, rvalue: &Rvalue<'tcx>) -> Option<UserTypeAnnotationIndex> {
match rvalue {
Rvalue::Use(_)
| Rvalue::ThreadLocalRef(_)
| Rvalue::Repeat(..)
| Rvalue::Ref(..)
| Rvalue::AddressOf(..)
Expand Down
1 change: 1 addition & 0 deletions src/librustc_mir/dataflow/impls/borrowed_locals.rs
Original file line number Diff line number Diff line change
Expand Up @@ -176,6 +176,7 @@ where

mir::Rvalue::Cast(..)
| mir::Rvalue::Use(..)
| mir::Rvalue::ThreadLocalRef(..)
| mir::Rvalue::Repeat(..)
| mir::Rvalue::Len(..)
| mir::Rvalue::BinaryOp(..)
Expand Down
1 change: 1 addition & 0 deletions src/librustc_mir/dataflow/move_paths/builder.rs
Original file line number Diff line number Diff line change
Expand Up @@ -324,6 +324,7 @@ impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> {

fn gather_rvalue(&mut self, rvalue: &Rvalue<'tcx>) {
match *rvalue {
Rvalue::ThreadLocalRef(_) => {} // not-a-move
Rvalue::Use(ref operand)
| Rvalue::Repeat(ref operand, _)
| Rvalue::Cast(_, ref operand, _)
Expand Down
7 changes: 7 additions & 0 deletions src/librustc_mir/interpret/machine.rs
Original file line number Diff line number Diff line change
Expand Up @@ -358,6 +358,13 @@ pub trait Machine<'mir, 'tcx>: Sized {
_mem: &Memory<'mir, 'tcx, Self>,
_ptr: Pointer<Self::PointerTag>,
) -> InterpResult<'tcx, u64>;

fn thread_local_alloc_id(
_ecx: &mut InterpCx<'mir, 'tcx, Self>,
did: DefId,
) -> InterpResult<'tcx, AllocId> {
throw_unsup!(ThreadLocalStatic(did))
}
}

// A lot of the flexibility above is just needed for `Miri`, but all "compile-time" machines
Expand Down
2 changes: 2 additions & 0 deletions src/librustc_mir/interpret/memory.rs
Original file line number Diff line number Diff line change
Expand Up @@ -437,6 +437,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
Some(GlobalAlloc::Function(..)) => throw_ub!(DerefFunctionPointer(id)),
None => throw_ub!(PointerUseAfterFree(id)),
Some(GlobalAlloc::Static(def_id)) => {
assert!(!tcx.is_thread_local_static(def_id));
// Notice that every static has two `AllocId` that will resolve to the same
// thing here: one maps to `GlobalAlloc::Static`, this is the "lazy" ID,
// and the other one is maps to `GlobalAlloc::Memory`, this is returned by
Expand Down Expand Up @@ -592,6 +593,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
// be held throughout the match.
match self.tcx.get_global_alloc(id) {
Some(GlobalAlloc::Static(did)) => {
assert!(!self.tcx.is_thread_local_static(did));
// Use size and align of the type.
let ty = self.tcx.type_of(did);
let layout = self.tcx.layout_of(ParamEnv::empty().and(ty)).unwrap();
Expand Down
6 changes: 6 additions & 0 deletions src/librustc_mir/interpret/step.rs
Original file line number Diff line number Diff line change
Expand Up @@ -141,6 +141,12 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {

use rustc_middle::mir::Rvalue::*;
match *rvalue {
ThreadLocalRef(did) => {
let id = M::thread_local_alloc_id(self, did)?;
let val = Scalar::Ptr(self.tag_global_base_pointer(id.into()));
self.write_scalar(val, dest)?;
}

Use(ref operand) => {
// Avoid recomputing the layout
let op = self.eval_operand(operand, Some(dest.layout))?;
Expand Down
1 change: 1 addition & 0 deletions src/librustc_mir/interpret/validity.rs
Original file line number Diff line number Diff line change
Expand Up @@ -418,6 +418,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
// Skip validation entirely for some external statics
let alloc_kind = self.ecx.tcx.get_global_alloc(ptr.alloc_id);
if let Some(GlobalAlloc::Static(did)) = alloc_kind {
assert!(!self.ecx.tcx.is_thread_local_static(did));
// See const_eval::machine::MemoryExtra::can_access_statics for why
// this check is so important.
// This check is reachable when the const just referenced the static,
Expand Down
1 change: 1 addition & 0 deletions src/librustc_mir/monomorphize/collector.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1143,6 +1143,7 @@ fn create_mono_items_for_default_impls<'tcx>(
fn collect_miri<'tcx>(tcx: TyCtxt<'tcx>, alloc_id: AllocId, output: &mut Vec<MonoItem<'tcx>>) {
match tcx.global_alloc(alloc_id) {
GlobalAlloc::Static(def_id) => {
assert!(!tcx.is_thread_local_static(def_id));
let instance = Instance::mono(tcx, def_id);
if should_monomorphize_locally(tcx, &instance) {
trace!("collecting static {:?}", def_id);
Expand Down
4 changes: 3 additions & 1 deletion src/librustc_mir/transform/check_consts/qualifs.rs
Original file line number Diff line number Diff line change
Expand Up @@ -153,7 +153,9 @@ where
F: FnMut(Local) -> bool,
{
match rvalue {
Rvalue::NullaryOp(..) => Q::in_any_value_of_ty(cx, rvalue.ty(cx.body, cx.tcx)),
Rvalue::ThreadLocalRef(_) | Rvalue::NullaryOp(..) => {
Q::in_any_value_of_ty(cx, rvalue.ty(cx.body, cx.tcx))
}

Rvalue::Discriminant(place) | Rvalue::Len(place) => {
in_place::<Q, _>(cx, in_local, place.as_ref())
Expand Down
12 changes: 7 additions & 5 deletions src/librustc_mir/transform/check_consts/validation.rs
Original file line number Diff line number Diff line change
Expand Up @@ -263,11 +263,11 @@ impl Validator<'mir, 'tcx> {
}

fn check_static(&mut self, def_id: DefId, span: Span) {
if self.tcx.is_thread_local_static(def_id) {
self.check_op_spanned(ops::ThreadLocalAccess, span)
} else {
self.check_op_spanned(ops::StaticAccess, span)
}
assert!(
!self.tcx.is_thread_local_static(def_id),
"tls access is checked in `Rvalue::ThreadLocalRef"
);
self.check_op_spanned(ops::StaticAccess, span)
}
}

Expand Down Expand Up @@ -332,6 +332,8 @@ impl Visitor<'tcx> for Validator<'mir, 'tcx> {
self.super_rvalue(rvalue, location);

match *rvalue {
Rvalue::ThreadLocalRef(_) => self.check_op(ops::ThreadLocalAccess),

Rvalue::Use(_)
| Rvalue::Repeat(..)
| Rvalue::UnaryOp(UnOp::Neg, _)
Expand Down
2 changes: 2 additions & 0 deletions src/librustc_mir/transform/promote_consts.rs
Original file line number Diff line number Diff line change
Expand Up @@ -603,6 +603,8 @@ impl<'tcx> Validator<'_, 'tcx> {
}

match rvalue {
Rvalue::ThreadLocalRef(_) => Err(Unpromotable),

Rvalue::NullaryOp(..) => Ok(()),

Rvalue::Discriminant(place) | Rvalue::Len(place) => self.validate_place(place.as_ref()),
Expand Down
3 changes: 3 additions & 0 deletions src/librustc_mir/transform/qualify_min_const_fn.rs
Original file line number Diff line number Diff line change
Expand Up @@ -156,6 +156,9 @@ fn check_rvalue(
span: Span,
) -> McfResult {
match rvalue {
Rvalue::ThreadLocalRef(_) => {
Err((span, "cannot access thread local storage in const fn".into()))
}
Rvalue::Repeat(operand, _) | Rvalue::Use(operand) => {
check_operand(tcx, operand, span, def_id, body)
}
Expand Down
1 change: 1 addition & 0 deletions src/librustc_mir_build/build/expr/as_place.rs
Original file line number Diff line number Diff line change
Expand Up @@ -258,6 +258,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
| ExprKind::InlineAsm { .. }
| ExprKind::LlvmInlineAsm { .. }
| ExprKind::Yield { .. }
| ExprKind::ThreadLocalRef(_)
| ExprKind::Call { .. } => {
// these are not places, so we need to make a temporary.
debug_assert!(match Category::of(&expr.kind) {
Expand Down
1 change: 1 addition & 0 deletions src/librustc_mir_build/build/expr/as_rvalue.rs
Original file line number Diff line number Diff line change
Expand Up @@ -53,6 +53,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
let source_info = this.source_info(expr_span);

match expr.kind {
ExprKind::ThreadLocalRef(did) => block.and(Rvalue::ThreadLocalRef(did)),
ExprKind::Scope { region_scope, lint_level, value } => {
let region_scope = (region_scope, source_info);
this.in_scope(region_scope, lint_level, |this| this.as_rvalue(block, scope, value))
Expand Down
16 changes: 12 additions & 4 deletions src/librustc_mir_build/build/expr/as_temp.rs
Original file line number Diff line number Diff line change
Expand Up @@ -63,10 +63,18 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
if let Some(tail_info) = this.block_context.currently_in_block_tail() {
local_decl = local_decl.block_tail(tail_info);
}
if let ExprKind::StaticRef { def_id, .. } = expr.kind {
let is_thread_local = this.hir.tcx().is_thread_local_static(def_id);
local_decl.internal = true;
local_decl.local_info = Some(box LocalInfo::StaticRef { def_id, is_thread_local });
match expr.kind {
ExprKind::StaticRef { def_id, .. } => {
assert!(!this.hir.tcx().is_thread_local_static(def_id));
local_decl.internal = true;
local_decl.local_info = Some(box LocalInfo::StaticRef { def_id, is_thread_local: false });
}
ExprKind::ThreadLocalRef(def_id) => {
assert!(this.hir.tcx().is_thread_local_static(def_id));
local_decl.internal = true;
local_decl.local_info = Some(box LocalInfo::StaticRef { def_id, is_thread_local: true });
}
_ => {}
}
this.local_decls.push(local_decl)
};
Expand Down
1 change: 1 addition & 0 deletions src/librustc_mir_build/build/expr/category.rs
Original file line number Diff line number Diff line change
Expand Up @@ -65,6 +65,7 @@ impl Category {
| ExprKind::Repeat { .. }
| ExprKind::Assign { .. }
| ExprKind::AssignOp { .. }
| ExprKind::ThreadLocalRef(_)
| ExprKind::LlvmInlineAsm { .. } => Some(Category::Rvalue(RvalueFunc::AsRvalue)),

ExprKind::Literal { .. } | ExprKind::StaticRef { .. } => Some(Category::Constant),
Expand Down
1 change: 1 addition & 0 deletions src/librustc_mir_build/build/expr/into.rs
Original file line number Diff line number Diff line change
Expand Up @@ -445,6 +445,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
| ExprKind::Tuple { .. }
| ExprKind::Closure { .. }
| ExprKind::Literal { .. }
| ExprKind::ThreadLocalRef(_)
| ExprKind::StaticRef { .. } => {
debug_assert!(match Category::of(&expr.kind).unwrap() {
// should be handled above
Expand Down
21 changes: 9 additions & 12 deletions src/librustc_mir_build/hair/cx/expr.rs
Original file line number Diff line number Diff line change
Expand Up @@ -856,20 +856,17 @@ fn convert_path_expr<'a, 'tcx>(
// a constant reference (or constant raw pointer for `static mut`) in MIR
Res::Def(DefKind::Static, id) => {
let ty = cx.tcx.static_ptr_ty(id);
let ptr = cx.tcx.create_static_alloc(id);
let temp_lifetime = cx.region_scope_tree.temporary_scope(expr.hir_id.local_id);
ExprKind::Deref {
arg: Expr {
ty,
temp_lifetime,
span: expr.span,
kind: ExprKind::StaticRef {
literal: ty::Const::from_scalar(cx.tcx, Scalar::Ptr(ptr.into()), ty),
def_id: id,
},
let kind = if cx.tcx.is_thread_local_static(id) {
ExprKind::ThreadLocalRef(id)
} else {
let ptr = cx.tcx.create_static_alloc(id);
ExprKind::StaticRef {
literal: ty::Const::from_scalar(cx.tcx, Scalar::Ptr(ptr.into()), ty),
def_id: id,
}
.to_ref(),
}
};
ExprKind::Deref { arg: Expr { ty, temp_lifetime, span: expr.span, kind }.to_ref() }
}

Res::Local(var_hir_id) => convert_var(cx, expr, var_hir_id),
Expand Down
2 changes: 2 additions & 0 deletions src/librustc_mir_build/hair/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -285,6 +285,8 @@ crate enum ExprKind<'tcx> {
options: InlineAsmOptions,
line_spans: &'tcx [Span],
},
/// An expression taking a reference to a thread local.
ThreadLocalRef(DefId),
LlvmInlineAsm {
asm: &'tcx hir::LlvmInlineAsmInner,
outputs: Vec<ExprRef<'tcx>>,
Expand Down
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