I implemented the original allocation elision in JavaScriptCore and then oversaw the development of the pass that superseded mine. Huge speedup, but very hit o

I implemented the original allocation elision in JavaScriptCore and then oversaw the development of the pass that superseded mine. Huge speedup, but very hit or miss. Out of a large suite of benchmarks, 90% of the tests saw no change and 10% saw improvements of 3x or so. Note each of these tests was itself a large program; these weren’t some BS microbenchmarks. Maybe someone from V8 can comment but my understanding is they had a similar experience. So it’s possible that someone measured this being perf neutral, if they used a too small benchmark suite.