On 22 Sep 2022, at 01:49, Quincey Morris <quinceymorris@...> wrote:
I really think you should start by asking this question over in the Swift forums, in case there is some compiler-specific answer that can immediately explain the result. It could be a compiler code generation deficiency, but there are many other possibilities. For example, a colleague of mine speculated that there could be reasons why the M1 Mac ran the Rosetta translation on a *performance* core, but ran the Apple Silicon version on an *efficiency* core.
I was wondering about the P/E cores too. Perhaps you can avoid that difference by using GCD + QOS to explicitly run the calculation on the desired kind of core. Though I guess we don’t actually know if Rosetta always runs high QOS Intel threads on high QOS M1 threads..
But yes, Gerriet’s good spot about the use of >>= looks like something for the compiler/codegen folks.
