  This paper argues for an accelerator development toolchain that takes into
account the whole system containing the accelerator. With whole-system
visibility, the toolchain can better assist accelerator scoping and composition
in the context of the expected workloads and intended performance objectives.
Despite being focused on the 'meta-level' of accelerators, this would build on
existing and ongoing DSLs and toolchains for accelerator design. Basing this on
our experience in programmable networking and reconfigurable-hardware
programming, we propose an integrative approach that relies on three
activities: (i) generalizing the focus of acceleration to offloading to
accommodate a broader variety of non-functional needs -- such as security and
power use -- while using similar implementation approaches, (ii) discovering
what to offload, and to what hardware, through semi-automated analysis of a
whole system that might compose different offload choices that changeover time,
(iii) connecting with research and state-of-the-art approaches for using
domain-specific languages (DSLs) and high-level synthesis (HLS) systems for
custom offload development. We outline how this integration can drive new
development tooling that accepts models of programs and resources to assist
system designers through design-space exploration for the accelerated system.
