Ask HN: Should i build an auto-parallelizer for C or for JAVA?

Assume that we focus on desktop and mobile type programs. Mostly OO source code, linux userland tools, Office, android software..

If you could choose just one language for your tool - which one would it be?!

I am specifically ignoring HPC, numerical workloads, and server tools. These are already hand-crafted, partially parallelized, and fairly efficient at what they do.