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Rollup merge of #87583 - tmiasko:compression-cache, r=wesleywiser

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Refactor compression cache in v0 symbol mangler

* Remove redundant option around compression caches (they are always present).
* Flatten compression caches into symbol mangler to avoid dynamic memory allocation.
* Implement printer for `&mut SymbolMangler` instead of `SymbolMangler` to avoid passing now slightly larger symbol mangler by value.
This commit is contained in:
Yuki Okushi 2021-07-30 16:26:58 +09:00 • committed by GitHub
commit 1757d6b34d
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1 changed files with 32 additions and 45 deletions
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77
compiler/rustc_symbol_mangling/src/v0.rs
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@ -23,15 +23,12 @@ pub(super) fn mangle(
let substs = tcx.normalize_erasing_regions(ty::ParamEnv::reveal_all(), instance.substs);
let prefix = "_R";
let mut cx = SymbolMangler {
let mut cx = &mut SymbolMangler {
tcx,
compress: Some(Box::new(CompressionCaches {
start_offset: prefix.len(),
paths: FxHashMap::default(),
types: FxHashMap::default(),
consts: FxHashMap::default(),
})),
start_offset: prefix.len(),
paths: FxHashMap::default(),
types: FxHashMap::default(),
consts: FxHashMap::default(),
binders: vec![],
out: String::from(prefix),
};
@ -52,17 +49,7 @@ pub(super) fn mangle(
if let Some(instantiating_crate) = instantiating_crate {
cx = cx.print_def_path(instantiating_crate.as_def_id(), &[]).unwrap();
}
cx.out
}
struct CompressionCaches<'tcx> {
// The length of the prefix in `out` (e.g. 2 for `_R`).
start_offset: usize,
// The values are start positions in `out`, in bytes.
paths: FxHashMap<(DefId, &'tcx [GenericArg<'tcx>]), usize>,
types: FxHashMap<Ty<'tcx>, usize>,
consts: FxHashMap<&'tcx ty::Const<'tcx>, usize>,
std::mem::take(&mut cx.out)
}
struct BinderLevel {
@ -81,9 +68,15 @@ struct BinderLevel {
struct SymbolMangler<'tcx> {
tcx: TyCtxt<'tcx>,
compress: Option<Box<CompressionCaches<'tcx>>>,
binders: Vec<BinderLevel>,
out: String,
/// The length of the prefix in `out` (e.g. 2 for `_R`).
start_offset: usize,
/// The values are start positions in `out`, in bytes.
paths: FxHashMap<(DefId, &'tcx [GenericArg<'tcx>]), usize>,
types: FxHashMap<Ty<'tcx>, usize>,
consts: FxHashMap<&'tcx ty::Const<'tcx>, usize>,
}
impl SymbolMangler<'tcx> {
@ -160,13 +153,13 @@ impl SymbolMangler<'tcx> {
self.push(ident);
}
fn path_append_ns(
mut self,
print_prefix: impl FnOnce(Self) -> Result<Self, !>,
fn path_append_ns<'a>(
mut self: &'a mut Self,
print_prefix: impl FnOnce(&'a mut Self) -> Result<&'a mut Self, !>,
ns: char,
disambiguator: u64,
name: &str,
) -> Result<Self, !> {
) -> Result<&'a mut Self, !> {
self.push("N");
self.out.push(ns);
self = print_prefix(self)?;
@ -175,17 +168,17 @@ impl SymbolMangler<'tcx> {
Ok(self)
}
fn print_backref(mut self, i: usize) -> Result<Self, !> {
fn print_backref(&mut self, i: usize) -> Result<&mut Self, !> {
self.push("B");
self.push_integer_62((i - self.compress.as_ref().unwrap().start_offset) as u64);
self.push_integer_62((i - self.start_offset) as u64);
Ok(self)
}
fn in_binder<T>(
mut self,
fn in_binder<'a, T>(
mut self: &'a mut Self,
value: &ty::Binder<'tcx, T>,
print_value: impl FnOnce(Self, &T) -> Result<Self, !>,
) -> Result<Self, !>
print_value: impl FnOnce(&'a mut Self, &T) -> Result<&'a mut Self, !>,
) -> Result<&'a mut Self, !>
where
T: TypeFoldable<'tcx>,
{
@ -218,7 +211,7 @@ impl SymbolMangler<'tcx> {
}
}
impl Printer<'tcx> for SymbolMangler<'tcx> {
impl Printer<'tcx> for &mut SymbolMangler<'tcx> {
type Error = !;
type Path = Self;
@ -236,7 +229,7 @@ impl Printer<'tcx> for SymbolMangler<'tcx> {
def_id: DefId,
substs: &'tcx [GenericArg<'tcx>],
) -> Result<Self::Path, Self::Error> {
if let Some(&i) = self.compress.as_ref().and_then(|c| c.paths.get(&(def_id, substs))) {
if let Some(&i) = self.paths.get(&(def_id, substs)) {
return self.print_backref(i);
}
let start = self.out.len();
@ -246,9 +239,7 @@ impl Printer<'tcx> for SymbolMangler<'tcx> {
// Only cache paths that do not refer to an enclosing
// binder (which would change depending on context).
if !substs.iter().any(|k| k.has_escaping_bound_vars()) {
if let Some(c) = &mut self.compress {
c.paths.insert((def_id, substs), start);
}
self.paths.insert((def_id, substs), start);
}
Ok(self)
}
@ -312,7 +303,7 @@ impl Printer<'tcx> for SymbolMangler<'tcx> {
Ok(self)
}
fn print_region(mut self, region: ty::Region<'_>) -> Result<Self::Region, Self::Error> {
fn print_region(self, region: ty::Region<'_>) -> Result<Self::Region, Self::Error> {
let i = match *region {
// Erased lifetimes use the index 0, for a
// shorter mangling of `L_`.
@ -367,7 +358,7 @@ impl Printer<'tcx> for SymbolMangler<'tcx> {
return Ok(self);
}
if let Some(&i) = self.compress.as_ref().and_then(|c| c.types.get(&ty)) {
if let Some(&i) = self.types.get(&ty) {
return self.print_backref(i);
}
let start = self.out.len();
@ -476,9 +467,7 @@ impl Printer<'tcx> for SymbolMangler<'tcx> {
// Only cache types that do not refer to an enclosing
// binder (which would change depending on context).
if !ty.has_escaping_bound_vars() {
if let Some(c) = &mut self.compress {
c.types.insert(ty, start);
}
self.types.insert(ty, start);
}
Ok(self)
}
@ -545,7 +534,7 @@ impl Printer<'tcx> for SymbolMangler<'tcx> {
}
fn print_const(mut self, ct: &'tcx ty::Const<'tcx>) -> Result<Self::Const, Self::Error> {
if let Some(&i) = self.compress.as_ref().and_then(|c| c.consts.get(&ct)) {
if let Some(&i) = self.consts.get(&ct) {
return self.print_backref(i);
}
let start = self.out.len();
@ -583,14 +572,12 @@ impl Printer<'tcx> for SymbolMangler<'tcx> {
// Only cache consts that do not refer to an enclosing
// binder (which would change depending on context).
if !ct.has_escaping_bound_vars() {
if let Some(c) = &mut self.compress {
c.consts.insert(ct, start);
}
self.consts.insert(ct, start);
}
Ok(self)
}
fn path_crate(mut self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
fn path_crate(self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
self.push("C");
let stable_crate_id = self.tcx.def_path_hash(cnum.as_def_id()).stable_crate_id();
self.push_disambiguator(stable_crate_id.to_u64());