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Commit1088cc4

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authored
OptimizeNanBoxedValue related operations (#4506)
Another batch of optimizations.- Optimize NanBoxedValue::clone by inlining the calls to`as_object/string/symbol/bigint`.- Optimize NanBoxedValue::tag_pointer by receiving a `NonNull` pointer,which removes the assertion we have there. Also marks the rarest path(unsupported platform) as a cold function.- Optimize GcHeader::inc_ref_count by marking the possible ref countoverflow as a cold path.### Main resultsRESULT Richards 237RESULT DeltaBlue 243RESULT Crypto 192RESULT RayTrace 524RESULT EarleyBoyer 618RESULT RegExp 87.6RESULT Splay 877RESULT NavierStokes 427SCORE 323### PR resultsRESULT Richards 229RESULT DeltaBlue 238RESULT Crypto 197RESULT RayTrace 532RESULT EarleyBoyer 635RESULT RegExp 91.8RESULT Splay 888RESULT NavierStokes 439SCORE 327
1 parentc9b1f94 commit1088cc4

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3 files changed

+71
-36
lines changed

3 files changed

+71
-36
lines changed

‎core/engine/src/bigint.rs‎

Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -7,6 +7,7 @@ use num_traits::{FromPrimitive, One, ToPrimitive, Zero, pow::Pow};
77
use std::{
88
fmt::{self,Display},
99
ops::{Add,BitAnd,BitOr,BitXor,Div,Mul,Neg,Rem,Shl,Shr,Sub},
10+
ptr::NonNull,
1011
rc::Rc,
1112
};
1213

@@ -334,8 +335,9 @@ impl JsBigInt {
334335
#[inline]
335336
#[must_use]
336337
#[allow(unused, reason ="only used in nan-boxed implementation of JsValue")]
337-
pub(crate)fninto_raw(self) ->*constRawBigInt{
338-
Rc::into_raw(self.inner)
338+
pub(crate)fninto_raw(self) ->NonNull<RawBigInt>{
339+
// SAFETY: `Rc::into_raw` must always return a non-null pointer.
340+
unsafe{NonNull::new_unchecked(Rc::into_raw(self.inner).cast_mut())}
339341
}
340342

341343
/// Constructs a `JsBigInt` from a pointer to [`RawBigInt`].

‎core/engine/src/value/inner/nan_boxed.rs‎

Lines changed: 52 additions & 30 deletions
Original file line numberDiff line numberDiff line change
@@ -115,7 +115,7 @@ use boa_string::{JsString, RawJsString};
115115
use core::fmt;
116116
use static_assertions::const_assert;
117117
use std::{
118-
mem::ManuallyDrop,
118+
mem::{self,ManuallyDrop},
119119
ptr::{self,NonNull},
120120
};
121121

@@ -139,6 +139,7 @@ const _NAN_BOX_COMPAT_CHECK: () = const {
139139
///
140140
/// All bit magic is done here.
141141
mod bits{
142+
use std::ptr::NonNull;
142143

143144
/// The mask for the bits that indicate if the value is a NaN-value.
144145
constMASK_NAN:u64 =0x7FF0_0000_0000_0000;
@@ -262,19 +263,29 @@ mod bits {
262263
value&MASK_BOOLEAN_VALUE !=0
263264
}
264265

265-
pub(super)fntag_pointer<T>(ptr:*mutT,type_mask:u64) ->u64{
266-
let value = ptr.addr()asu64;
266+
#[inline(always)]
267+
pub(super)fntag_pointer<T>(ptr:NonNull<T>,type_mask:u64) ->u64{
268+
// Mark this as `cold` since on well-behaved platforms
269+
// this will never be called.
270+
#[cold]
271+
#[inline(never)]
272+
fnunsupported_platform(){
273+
panic!(
274+
"this platform is not compatible with a nan-boxed `JsValueInner`\n\
275+
enable the `jsvalue-enum` feature to use the enum-based `JsValueInner`"
276+
)
277+
}
278+
279+
let value = ptr.addr().get()asu64;
267280
let value_masked:u64 = value&MASK_POINTER_VALUE;
268281

269282
// Assert alignment and location of the pointer.
270-
assert_eq!(
271-
value_masked, value,
272-
"this platform is not compatible with a nan-boxed `JsValueInner`\n\
273-
enable the `jsvalue-enum` feature to use the enum-based `JsValueInner`"
274-
);
275-
276-
// Cannot have a null pointer.
277-
assert_ne!(value_masked,0,"pointer is null");
283+
// TODO: we may want to have nan-boxing be the default only on
284+
// certain platforms, and make it an unsafe operation
285+
// to manually enable the implementation.
286+
if value_masked != value{
287+
unsupported_platform();
288+
}
278289

279290
value_masked | type_mask
280291
}
@@ -342,21 +353,32 @@ unsafe impl Trace for NanBoxedValue {
342353
implCloneforNanBoxedValue{
343354
#[inline(always)]
344355
fnclone(&self) ->Self{
345-
ifletSome(o) =self.as_object(){
346-
Self::object(o.clone())
347-
}elseifletSome(s) =self.as_string(){
348-
Self::string(s.clone())
349-
}elseifletSome(b) =self.as_bigint(){
350-
Self::bigint(b.clone())
351-
}elseifletSome(s) =self.as_symbol(){
352-
Self::symbol(s.clone())
353-
}else{
354-
Self{
355-
#[cfg(target_pointer_width ="32")]
356-
half:self.half,
357-
ptr:self.ptr,
356+
// This way of inlining ensures the compiler
357+
// knows it can convert the match into a
358+
// jump table.
359+
matchself.value()& bits::MASK_KIND{
360+
bits::MASK_OBJECT =>unsafe{
361+
mem::forget((*self.as_object_unchecked()).clone());
362+
},
363+
bits::MASK_STRING =>unsafe{
364+
mem::forget((*self.as_string_unchecked()).clone());
365+
},
366+
bits::MASK_SYMBOL =>unsafe{
367+
mem::forget((*self.as_symbol_unchecked()).clone());
368+
},
369+
bits::MASK_BIGINT =>unsafe{
370+
mem::forget((*self.as_bigint_unchecked()).clone());
371+
},
372+
_ =>{
373+
// Rest of the variants don't need additional handling.
358374
}
359375
}
376+
377+
Self{
378+
#[cfg(target_pointer_width ="32")]
379+
half:self.half,
380+
ptr:self.ptr,
381+
}
360382
}
361383
}
362384

@@ -377,11 +399,11 @@ impl NanBoxedValue {
377399
/// pointer.
378400
///
379401
/// This preserves the provenance of the original pointer.
380-
fnfrom_object_like<T>(ptr:*mutT,addr:u64) ->Self{
402+
fnfrom_object_like<T>(ptr:NonNull<T>,addr:u64) ->Self{
381403
Self{
382404
#[cfg(target_pointer_width ="32")]
383405
half:(addr >>32)asu32,
384-
ptr: ptr.cast::<()>().with_addr(addrasusize),
406+
ptr: ptr.cast::<()>().as_ptr().with_addr(addrasusize),
385407
}
386408
}
387409

@@ -437,7 +459,7 @@ impl NanBoxedValue {
437459
#[must_use]
438460
#[inline(always)]
439461
pub(crate)fnbigint(value:JsBigInt) ->Self{
440-
let ptr = value.into_raw().cast_mut();
462+
let ptr = value.into_raw();
441463
let addr = bits::tag_pointer(ptr, bits::MASK_BIGINT);
442464
Self::from_object_like(ptr, addr)
443465
}
@@ -446,7 +468,7 @@ impl NanBoxedValue {
446468
#[must_use]
447469
#[inline(always)]
448470
pub(crate)fnobject(value:JsObject) ->Self{
449-
let ptr = value.into_raw().as_ptr();
471+
let ptr = value.into_raw();
450472
let addr = bits::tag_pointer(ptr, bits::MASK_OBJECT);
451473
Self::from_object_like(ptr, addr)
452474
}
@@ -455,7 +477,7 @@ impl NanBoxedValue {
455477
#[must_use]
456478
#[inline(always)]
457479
pub(crate)fnsymbol(value:JsSymbol) ->Self{
458-
let ptr = value.into_raw().as_ptr();
480+
let ptr = value.into_raw();
459481
let addr = bits::tag_pointer(ptr, bits::MASK_SYMBOL);
460482
Self::from_object_like(ptr, addr)
461483
}
@@ -464,7 +486,7 @@ impl NanBoxedValue {
464486
#[must_use]
465487
#[inline(always)]
466488
pub(crate)fnstring(value:JsString) ->Self{
467-
let ptr = value.into_raw().as_ptr();
489+
let ptr = value.into_raw();
468490
let addr = bits::tag_pointer(ptr, bits::MASK_STRING);
469491
Self::from_object_like(ptr, addr)
470492
}

‎core/gc/src/internals/gc_header.rs‎

Lines changed: 15 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -59,12 +59,24 @@ impl GcHeader {
5959
self.non_root_count.get()&MARK_MASK !=0
6060
}
6161

62-
#[inline]
6362
pub(crate)fninc_ref_count(&self){
64-
self.ref_count.set(self.ref_count.get() +1);
63+
// Mark this as `cold` since the ref count will
64+
// (almost) never overflow.
65+
#[cold]
66+
#[inline(never)]
67+
fnoverflow_panic(){
68+
panic!("too many references to a gc allocation");
69+
}
70+
71+
let count =self.ref_count.get().wrapping_add(1);
72+
73+
self.ref_count.set(count);
74+
75+
if count ==0{
76+
overflow_panic();
77+
}
6578
}
6679

67-
#[inline]
6880
pub(crate)fndec_ref_count(&self){
6981
self.ref_count.set(self.ref_count.get() -1);
7082
}
@@ -75,7 +87,6 @@ impl GcHeader {
7587
///
7688
/// This only gives valid result if the we have run through the
7789
/// tracing non roots phase.
78-
#[inline]
7990
pub(crate)fnis_rooted(&self) ->bool{
8091
self.non_root_count() <self.ref_count()
8192
}

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