Scoping effort needed to support new CPU

Omar gcc.omar@gmail.com
Tue Apr 8 22:09:00 GMT 2008


Hi,
 My company is looking at the possibility of creating a new CPU core
for an embedded application. The goals for the CPU are (in order of
importance):
  1- High code density
  2- Low power
  3- Small silicon footprint (low gate count)

 We want to have GCC as the compiler, so my main goal here is to have
the GCC community help me to get an idea for the following:
1- How long will it take to port GCC to the new CPU. I know this is
question depend on many aspects, but just want to get a rough
estimate. Lets assume the CPU is a 16-bit RISC with a limited
instruction set, and that the person doing the port have experience
doing so. How will this estimate change with if the person doing the
port do not have any experience?
2- Are there any specific instructions that will make the port easier,
and/or help with the code density? We are quite early in the
development cycle, so we can add support to instructions that will
make it easier to GCC achieve our goals.
3- Any other issues that you think we should consider?
 3.1- For example, I am estimating that after the initial port, we
will need to allocate 1 moth worth of effort each year to maintain
this port (mainly to up-rev to newer GCC versions). Is this a sensible
number?

Thanks in advance for your comments!
-Omar



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