TrishAce Resident
While trying to stress test / benchmark a comparison for
(string) list
and
llDumpList2String
, I came across a register exhaustion for a script in lsl-luau that works in mono.
I'm reporting both as one canny because I'm unsure if these are related.
A) First, for the benchmark:
In LSO:
=== list-to-string benchmark: 100 iterations x 300 items ===
(string)list total = 1040.432007 ms mean = 10.404320 ms
llDumpList2String total = 1896.921143 ms mean = 18.969212 ms
ratio (string/dump) = 0.548485x
=== DONE ===
In Mono:
=== list-to-string benchmark: 100 iterations x 300 items ===
(string)list total = 226.023000 ms mean = 2.260230 ms
llDumpList2String total = 316.186000 ms mean = 3.161860 ms
ratio (string/dump) = 0.714842x
=== DONE ===
In LSL-LUAU:
=== list-to-string benchmark: 100 iterations x 300 items ===
(string)list total = 2287.902000 ms mean = 22.879020 ms
llDumpList2String total = 589.087000 ms mean = 5.890871 ms
ratio (string/dump) = 3.883810x
=== DONE ===
=== list-to-string benchmark: 100 reps x 500 items ===
(string)list total = 4536.675000 ms mean = 45.366750 ms
llDumpList2String total = 1022.474000 ms mean = 10.224740 ms
ratio (string/dump) = 4.436957x
=== DONE ===
Something about how casting a list to a string is way worse in lsl-luau. My thought was that it's likely something that could be optimized if llDumpList2String is about 4x faster already.
B) Second, a test script of the discrepancy is the following
default
{
state_entry()
{
integer i = 1;
string s =
(string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i +
(string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i +
(string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i +
(string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i +
(string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i +
(string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i +
(string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i +
(string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i +
(string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i +
(string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i + (string)i ;
llOwnerSay(s);
}
}
It prints "1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111" in mono, but in lsl-luau it fails to compile with "Out of registers when trying to allocate 1 registers: exceeded limit 255"
I doubt there are many real use cases where this would have an impact after switching off mono, but it is still a notable difference.