The insn is definitely js-specific though. The architecture has int-float conversion insns already which work fine for the purposes of almost all languages (dyn

The insn is definitely js-specific though. The architecture has int-float conversion insns already which work fine for the purposes of almost all languages (dynamic or not); but js requires some specific oddball semantics which this new insn provides. There are some details in this 2016 blogpost -- https://community.arm.com/processors/b/blog/posts/armv8-a-architecture-2016-additions https://community.arm.com/processors/b/blog/posts/armv8-a-ar...