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Don't look up layouts in STORE_ATTR_INSTANCE_OVERFLOW #491

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Don't look up layouts in STORE_ATTR_INSTANCE_OVERFLOW #491

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39 changes: 24 additions & 15 deletions runtime/interpreter-gen-x64.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1512,24 +1512,33 @@ void emitHandler<STORE_ATTR_INSTANCE>(EmitEnv* env) {
template <>
void emitHandler<STORE_ATTR_INSTANCE_OVERFLOW>(EmitEnv* env) {
ScratchReg r_base(env);
ScratchReg r_layout_id(env);
ScratchReg r_cache_value(env);
ScratchReg r_caches(env);
ScratchReg r_packed_location(env);
Label slow_path;

__ popq(r_base);
emitGetLayoutId(env, r_layout_id, r_base);
__ movq(r_caches, Address(env->frame, Frame::kCachesOffset));
emitIcLookupMonomorphic(env, &slow_path, r_cache_value, r_layout_id,
r_caches);
emitConvertFromSmallInt(env, r_cache_value);

{
ScratchReg r_scratch(env);
emitLoadOverflowTuple(env, r_scratch, r_layout_id, r_base);
// The real tuple index is -offset - 1, which is the same as ~offset.
__ notq(r_cache_value);
__ popq(Address(r_scratch, r_cache_value, TIMES_8, heapObjectDisp(0)));
ScratchReg r_layout_id(env);
ScratchReg r_caches(env);
__ popq(r_base);
emitGetLayoutId(env, r_layout_id, r_base);
__ movq(r_caches, Address(env->frame, Frame::kCachesOffset));
emitIcLookupMonomorphic(env, &slow_path, r_packed_location, r_layout_id,
r_caches);
}

ScratchReg r_overflow_offset(env);
// uword packed_location = SmallInt::cast(cached).value();
emitConvertFromSmallInt(env, r_packed_location);
__ movq(r_overflow_offset, r_packed_location);
// uword overflow_offset = packed_location & 0xffffffff;
__ andq(r_overflow_offset, Immediate(0xffffffff));
// uword offset = packed_location >> 32;
__ shrq(r_packed_location, Immediate(32));
{
ScratchReg r_overflow_tuple(env);
__ movq(r_overflow_tuple,
Address(r_base, r_overflow_offset, TIMES_1, heapObjectDisp(0)));
__ popq(Address(r_overflow_tuple, r_packed_location, TIMES_8,
heapObjectDisp(0)));
emitNextOpcode(env);
}

Expand Down
40 changes: 31 additions & 9 deletions runtime/interpreter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3288,9 +3288,20 @@ Continue Interpreter::storeAttrUpdateCache(Thread* thread, word arg,
icUpdateAttr(thread, caches, cache, saved_layout_id, location, name,
dependent);
} else {
rewriteCurrentBytecode(frame, STORE_ATTR_INSTANCE_OVERFLOW);
icUpdateAttr(thread, caches, cache, saved_layout_id, location, name,
dependent);
uword offset = -SmallInt::cast(*location).value() - 1;
Layout layout(&scope, thread->runtime()->layoutOf(*receiver));
uword overflow_offset = layout.overflowOffset();
// Save one bit for the SmallInt tag
uword packed_location = (offset << 32) | overflow_offset;
// We need to check that they fit in 32 bits each and 63 bits together.
if (Utils::fits<uint32_t>(offset) &&
Utils::fits<uint32_t>(overflow_offset) &&
SmallInt::isValid(packed_location)) {
location = SmallInt::fromWord(packed_location);
rewriteCurrentBytecode(frame, STORE_ATTR_INSTANCE_OVERFLOW);
icUpdateAttr(thread, caches, cache, saved_layout_id, location, name,
dependent);
}
}
} else {
// Layout transition.
Expand All @@ -3316,6 +3327,18 @@ Continue Interpreter::storeAttrUpdateCache(Thread* thread, word arg,
currentBytecode(thread) == STORE_ATTR_INSTANCE_OVERFLOW ||
currentBytecode(thread) == STORE_ATTR_POLYMORPHIC,
"unexpected opcode");
if (ic_state == ICState::kMonomorphic &&
currentBytecode(thread) == STORE_ATTR_INSTANCE_OVERFLOW) {
// Fix up the packed cache; save only the index into the overflow tuple.
// That's what STORE_ATTR_POLYMORPHIC expects. Also, make it negative
// again to indicate that it's an overflow offset.
word index = cache * kIcPointersPerEntry;
RawObject cached = caches.at(index + kIcEntryValueOffset);
uword packed_location = SmallInt::cast(cached).value();
caches.atPut(index + kIcEntryValueOffset,
SmallInt::fromWord(~(packed_location >> 32)));
}

if (saved_layout_id == receiver_layout_id) {
rewriteCurrentBytecode(frame, STORE_ATTR_POLYMORPHIC);
icUpdateAttr(thread, caches, cache, saved_layout_id, location, name,
Expand Down Expand Up @@ -3384,13 +3407,12 @@ HANDLER_INLINE Continue Interpreter::doStoreAttrInstanceOverflow(Thread* thread,
EVENT_CACHE(STORE_ATTR_INSTANCE_OVERFLOW);
return storeAttrUpdateCache(thread, arg, cache);
}
word offset = SmallInt::cast(cached).value();
DCHECK(offset < 0, "unexpected offset");
uword packed_location = SmallInt::cast(cached).value();
uword overflow_offset = packed_location & 0xffffffff;
uword offset = packed_location >> 32;
RawInstance instance = Instance::cast(receiver);
RawLayout layout = Layout::cast(thread->runtime()->layoutOf(receiver));
RawTuple overflow =
Tuple::cast(instance.instanceVariableAt(layout.overflowOffset()));
overflow.atPut(-offset - 1, thread->stackPeek(1));
RawTuple overflow = Tuple::cast(instance.instanceVariableAt(overflow_offset));
overflow.atPut(offset, thread->stackPeek(1));
thread->stackDrop(2);
return Continue::NEXT;
}
Expand Down