All interesting ... and I will try out each candidate and report back. It will be tested only on Hercules so in one sense not a fair test. On the other hand we could argue that that Hercules is S/370 done well ... meaning I agree with a comment that if a CPU manufacturer defines a bulk move command they should implement it fast!
One thing, modern compilers generally produce faster code than a human assembler programmer. This is because both of front end optimisations (e.g. reassigning / calculating values that have not changes), and backend optimisation based on loop unrolling, and instruction reordering based on CPU pipelines etc.
This is why LLVM is becoming the one toolchain to rule them all ... even IBM works with them to ensure mainframe CPU internals are fully leveraged.
A
