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Cleanup metadata and incremental cache processing of constants #49079

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Mar 19, 2018
Merged

Cleanup metadata and incremental cache processing of constants #49079

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82 changes: 81 additions & 1 deletion src/librustc/mir/interpret/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,11 +15,13 @@ pub use self::value::{PrimVal, PrimValKind, Value, Pointer};
use std::collections::BTreeMap;
use std::fmt;
use mir;
use ty;
use hir::def_id::DefId;
use ty::{self, TyCtxt};
use ty::layout::{self, Align, HasDataLayout};
use middle::region;
use std::iter;
use syntax::ast::Mutability;
use rustc_serialize::{Encoder, Decoder, Decodable, Encodable};

#[derive(Clone, Debug, PartialEq)]
pub enum Lock {
Expand Down Expand Up @@ -152,6 +154,84 @@ pub struct AllocId(pub u64);
impl ::rustc_serialize::UseSpecializedEncodable for AllocId {}
impl ::rustc_serialize::UseSpecializedDecodable for AllocId {}

pub const ALLOC_DISCRIMINANT: usize = 0;
pub const FN_DISCRIMINANT: usize = 1;

pub fn specialized_encode_alloc_id<
'a, 'tcx,
E: Encoder,
>(
encoder: &mut E,
tcx: TyCtxt<'a, 'tcx, 'tcx>,
alloc_id: AllocId,
shorthand: Option<usize>,
) -> Result<(), E::Error> {
if let Some(shorthand) = shorthand {
return shorthand.encode(encoder);
}
if let Some(alloc) = tcx.interpret_interner.get_alloc(alloc_id) {
trace!("encoding {:?} with {:#?}", alloc_id, alloc);
ALLOC_DISCRIMINANT.encode(encoder)?;
alloc.encode(encoder)?;
tcx.interpret_interner
.get_corresponding_static_def_id(alloc_id)
.encode(encoder)?;
} else if let Some(fn_instance) = tcx.interpret_interner.get_fn(alloc_id) {
trace!("encoding {:?} with {:#?}", alloc_id, fn_instance);
FN_DISCRIMINANT.encode(encoder)?;
fn_instance.encode(encoder)?;
} else {
bug!("alloc id without corresponding allocation: {}", alloc_id);
}
Ok(())
}

pub fn specialized_decode_alloc_id<
'a, 'tcx,
D: Decoder,
CACHE: FnOnce(&mut D, usize, AllocId),
SHORT: FnOnce(&mut D, usize) -> Result<AllocId, D::Error>
>(
decoder: &mut D,
tcx: TyCtxt<'a, 'tcx, 'tcx>,
pos: usize,
cache: CACHE,
short: SHORT,
) -> Result<AllocId, D::Error> {
match usize::decode(decoder)? {
ALLOC_DISCRIMINANT => {
let alloc_id = tcx.interpret_interner.reserve();
trace!("creating alloc id {:?} at {}", alloc_id, pos);
// insert early to allow recursive allocs
cache(decoder, pos, alloc_id);

let allocation = Allocation::decode(decoder)?;
trace!("decoded alloc {:?} {:#?}", alloc_id, allocation);
let allocation = tcx.intern_const_alloc(allocation);
tcx.interpret_interner.intern_at_reserved(alloc_id, allocation);

if let Some(glob) = Option::<DefId>::decode(decoder)? {
tcx.interpret_interner.cache(glob, alloc_id);
}

Ok(alloc_id)
},
FN_DISCRIMINANT => {
trace!("creating fn alloc id at {}", pos);
let instance = ty::Instance::decode(decoder)?;
trace!("decoded fn alloc instance: {:?}", instance);
let id = tcx.interpret_interner.create_fn_alloc(instance);
trace!("created fn alloc id: {:?}", id);
cache(decoder, pos, id);
Ok(id)
},
shorthand => {
trace!("loading shorthand {}", shorthand);
short(decoder, shorthand)
},
}
}

impl fmt::Display for AllocId {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{}", self.0)
Expand Down
126 changes: 63 additions & 63 deletions src/librustc/ty/maps/on_disk_cache.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -75,6 +75,13 @@ pub struct OnDiskCache<'sess> {
// A map from dep-node to the position of any associated diagnostics in
// `serialized_data`.
prev_diagnostics_index: FxHashMap<SerializedDepNodeIndex, AbsoluteBytePos>,

// A cache to ensure we don't read allocations twice
interpret_alloc_cache: RefCell<FxHashMap<usize, interpret::AllocId>>,

// A map from positions to size of the serialized allocation
// so we can skip over already processed allocations
interpret_alloc_size: RefCell<FxHashMap<usize, usize>>,
}

// This type is used only for (de-)serialization.
Expand Down Expand Up @@ -140,6 +147,8 @@ impl<'sess> OnDiskCache<'sess> {
query_result_index: footer.query_result_index.into_iter().collect(),
prev_diagnostics_index: footer.diagnostics_index.into_iter().collect(),
synthetic_expansion_infos: RefCell::new(FxHashMap()),
interpret_alloc_cache: RefCell::new(FxHashMap::default()),
interpret_alloc_size: RefCell::new(FxHashMap::default()),
}
}

Expand All @@ -155,6 +164,8 @@ impl<'sess> OnDiskCache<'sess> {
query_result_index: FxHashMap(),
prev_diagnostics_index: FxHashMap(),
synthetic_expansion_infos: RefCell::new(FxHashMap()),
interpret_alloc_cache: RefCell::new(FxHashMap::default()),
interpret_alloc_size: RefCell::new(FxHashMap::default()),
}
}

Expand Down Expand Up @@ -381,7 +392,8 @@ impl<'sess> OnDiskCache<'sess> {
file_index_to_file: &self.file_index_to_file,
file_index_to_stable_id: &self.file_index_to_stable_id,
synthetic_expansion_infos: &self.synthetic_expansion_infos,
interpret_alloc_cache: FxHashMap::default(),
interpret_alloc_cache: &self.interpret_alloc_cache,
interpret_alloc_size: &self.interpret_alloc_size,
};

match decode_tagged(&mut decoder, dep_node_index) {
Expand Down Expand Up @@ -443,7 +455,8 @@ struct CacheDecoder<'a, 'tcx: 'a, 'x> {
synthetic_expansion_infos: &'x RefCell<FxHashMap<AbsoluteBytePos, SyntaxContext>>,
file_index_to_file: &'x RefCell<FxHashMap<FileMapIndex, Lrc<FileMap>>>,
file_index_to_stable_id: &'x FxHashMap<FileMapIndex, StableFilemapId>,
interpret_alloc_cache: FxHashMap<usize, interpret::AllocId>,
interpret_alloc_cache: &'x RefCell<FxHashMap<usize, interpret::AllocId>>,
interpret_alloc_size: &'x RefCell<FxHashMap<usize, usize>>,
}

impl<'a, 'tcx, 'x> CacheDecoder<'a, 'tcx, 'x> {
Expand Down Expand Up @@ -565,47 +578,37 @@ implement_ty_decoder!( CacheDecoder<'a, 'tcx, 'x> );

impl<'a, 'tcx, 'x> SpecializedDecoder<interpret::AllocId> for CacheDecoder<'a, 'tcx, 'x> {
fn specialized_decode(&mut self) -> Result<interpret::AllocId, Self::Error> {
const MAX1: usize = usize::max_value() - 1;
let tcx = self.tcx;
let pos = TyDecoder::position(self);
match usize::decode(self)? {
::std::usize::MAX => {
let alloc_id = tcx.interpret_interner.reserve();
trace!("creating alloc id {:?} at {}", alloc_id, pos);
// insert early to allow recursive allocs
self.interpret_alloc_cache.insert(pos, alloc_id);

let allocation = interpret::Allocation::decode(self)?;
trace!("decoded alloc {:?} {:#?}", alloc_id, allocation);
let allocation = self.tcx.intern_const_alloc(allocation);
tcx.interpret_interner.intern_at_reserved(alloc_id, allocation);

if let Some(glob) = Option::<DefId>::decode(self)? {
trace!("connecting alloc {:?} with {:?}", alloc_id, glob);
tcx.interpret_interner.cache(glob, alloc_id);
}

Ok(alloc_id)
},
MAX1 => {
trace!("creating fn alloc id at {}", pos);
let instance = ty::Instance::decode(self)?;
trace!("decoded fn alloc instance: {:?}", instance);
let id = tcx.interpret_interner.create_fn_alloc(instance);
trace!("created fn alloc id: {:?}", id);
self.interpret_alloc_cache.insert(pos, id);
Ok(id)
trace!("specialized_decode_alloc_id: {:?}", pos);
if let Some(cached) = self.interpret_alloc_cache.borrow().get(&pos).cloned() {
// if there's no end position we are currently deserializing a recursive
// allocation
if let Some(end) = self.interpret_alloc_size.borrow().get(&pos).cloned() {
trace!("{} already cached as {:?}", pos, cached);
// skip ahead
self.opaque.set_position(end);
return Ok(cached)
}
}
let id = interpret::specialized_decode_alloc_id(
self,
tcx,
pos,
|this, pos, alloc_id| {
assert!(this.interpret_alloc_cache.borrow_mut().insert(pos, alloc_id).is_none());
},
shorthand => {
trace!("loading shorthand {}", shorthand);
if let Some(&alloc_id) = self.interpret_alloc_cache.get(&shorthand) {
return Ok(alloc_id);
}
trace!("shorthand {} not cached, loading entire allocation", shorthand);
|this, shorthand| {
// need to load allocation
self.with_position(shorthand, |this| interpret::AllocId::decode(this))
},
}
this.with_position(shorthand, |this| interpret::AllocId::decode(this))
}
)?;
assert!(self
.interpret_alloc_size
.borrow_mut()
.insert(pos, TyDecoder::position(self))
.is_none());
Ok(id)
}
}
impl<'a, 'tcx, 'x> SpecializedDecoder<Span> for CacheDecoder<'a, 'tcx, 'x> {
Expand Down Expand Up @@ -806,30 +809,27 @@ impl<'enc, 'a, 'tcx, E> SpecializedEncoder<interpret::AllocId> for CacheEncoder<
where E: 'enc + ty_codec::TyEncoder
{
fn specialized_encode(&mut self, alloc_id: &interpret::AllocId) -> Result<(), Self::Error> {
trace!("encoding {:?} at {}", alloc_id, self.position());
if let Some(shorthand) = self.interpret_alloc_shorthands.get(alloc_id).cloned() {
trace!("encoding {:?} as shorthand to {}", alloc_id, shorthand);
return shorthand.encode(self);
}
let start = self.position();
// cache the allocation shorthand now, because the allocation itself might recursively
// point to itself.
self.interpret_alloc_shorthands.insert(*alloc_id, start);
if let Some(alloc) = self.tcx.interpret_interner.get_alloc(*alloc_id) {
trace!("encoding {:?} with {:#?}", alloc_id, alloc);
usize::max_value().encode(self)?;
alloc.encode(self)?;
self.tcx.interpret_interner
.get_corresponding_static_def_id(*alloc_id)
.encode(self)?;
} else if let Some(fn_instance) = self.tcx.interpret_interner.get_fn(*alloc_id) {
trace!("encoding {:?} with {:#?}", alloc_id, fn_instance);
(usize::max_value() - 1).encode(self)?;
fn_instance.encode(self)?;
} else {
bug!("alloc id without corresponding allocation: {}", alloc_id);
}
Ok(())
use std::collections::hash_map::Entry;
let tcx = self.tcx;
let pos = self.position();
let shorthand = match self.interpret_alloc_shorthands.entry(*alloc_id) {
Entry::Occupied(entry) => Some(entry.get().clone()),
Entry::Vacant(entry) => {
// ensure that we don't place any AllocIds at the very beginning
// of the metadata file, because that would end up making our indices
// not special. It is essentially impossible for that to happen,
// but let's make sure
assert!(pos != interpret::ALLOC_DISCRIMINANT && pos != interpret::FN_DISCRIMINANT);
entry.insert(pos);
None
},
};
interpret::specialized_encode_alloc_id(
self,
tcx,
*alloc_id,
shorthand,
)
}
}

Expand Down
68 changes: 30 additions & 38 deletions src/librustc_metadata/decoder.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,9 @@ pub struct DecodeContext<'a, 'tcx: 'a> {

// interpreter allocation cache
interpret_alloc_cache: FxHashMap<usize, interpret::AllocId>,
// a cache for sizes of interpreter allocations
// needed to skip already deserialized allocations
interpret_alloc_size: FxHashMap<usize, usize>,
}

/// Abstract over the various ways one can create metadata decoders.
Expand All @@ -77,6 +80,7 @@ pub trait Metadata<'a, 'tcx>: Copy {
last_filemap_index: 0,
lazy_state: LazyState::NoNode,
interpret_alloc_cache: FxHashMap::default(),
interpret_alloc_size: FxHashMap::default(),
}
}
}
Expand Down Expand Up @@ -282,46 +286,34 @@ impl<'a, 'tcx> SpecializedDecoder<LocalDefId> for DecodeContext<'a, 'tcx> {

impl<'a, 'tcx> SpecializedDecoder<interpret::AllocId> for DecodeContext<'a, 'tcx> {
fn specialized_decode(&mut self) -> Result<interpret::AllocId, Self::Error> {
const MAX1: usize = usize::max_value() - 1;
let tcx = self.tcx.unwrap();
let tcx = self.tcx.expect("need tcx for AllocId decoding");
let pos = self.position();
match usize::decode(self)? {
::std::usize::MAX => {
let alloc_id = tcx.interpret_interner.reserve();
trace!("creating alloc id {:?} at {}", alloc_id, pos);
// insert early to allow recursive allocs
self.interpret_alloc_cache.insert(pos, alloc_id);

let allocation = interpret::Allocation::decode(self)?;
trace!("decoded alloc {:?} {:#?}", alloc_id, allocation);
let allocation = self.tcx.unwrap().intern_const_alloc(allocation);
tcx.interpret_interner.intern_at_reserved(alloc_id, allocation);

if let Some(glob) = Option::<DefId>::decode(self)? {
tcx.interpret_interner.cache(glob, alloc_id);
}

Ok(alloc_id)
},
MAX1 => {
trace!("creating fn alloc id at {}", pos);
let instance = ty::Instance::decode(self)?;
trace!("decoded fn alloc instance: {:?}", instance);
let id = tcx.interpret_interner.create_fn_alloc(instance);
trace!("created fn alloc id: {:?}", id);
self.interpret_alloc_cache.insert(pos, id);
Ok(id)
},
shorthand => {
trace!("loading shorthand {}", shorthand);
if let Some(&alloc_id) = self.interpret_alloc_cache.get(&shorthand) {
return Ok(alloc_id);
}
trace!("shorthand {} not cached, loading entire allocation", shorthand);
// need to load allocation
self.with_position(shorthand, |this| interpret::AllocId::decode(this))
},
if let Some(cached) = self.interpret_alloc_cache.get(&pos).cloned() {
// if there's no end position we are currently deserializing a recursive
// allocation
if let Some(end) = self.interpret_alloc_size.get(&pos).cloned() {
trace!("{} already cached as {:?}", pos, cached);
// skip ahead
self.opaque.set_position(end);
return Ok(cached)
}
}
let id = interpret::specialized_decode_alloc_id(
self,
tcx,
pos,
|this, pos, alloc_id| { this.interpret_alloc_cache.insert(pos, alloc_id); },
|this, shorthand| {
// need to load allocation
this.with_position(shorthand, |this| interpret::AllocId::decode(this))
}
)?;
let end_pos = self.position();
assert!(self
.interpret_alloc_size
.insert(pos, end_pos)
.is_none());
Ok(id)
}
}

Expand Down
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