I find it curious - and slightly scary - that as the world is stampeding towards increasingly-parallelized computing models, most of us in ASIC design are becoming increasingly thwarted by the limitations of functional simulation - which, by and large - is pretty much single-threaded. I mean, we're supposed to be designing to keep up with Moore, and our simulator performance has pretty much flat-lined. And even more alarming, I've heard very few ASIC people even talk about it.
First of all, we try to circumvent simulating the ASIC design by debugging the design in FPGAs. We then simulate the working design in software on our own small supercomputer built with these FPGAs. Simulating on many cores and running the design in FPGAs should bring us to the point where we can make a wafer scale integration at 180nm. Imagine 10000 cores on an 8 inch wafer.
Our software stack uses adaptive compilation to reconfigurable hardware, so we can identify hotspots in the code that can be compiled to the FPGA at runtime. Eventually we will be able to write and debug the whole ASIC in our software at runtime on the FPGA.
Simulating a single core is not to hard because our microcode processors is small. The ring network connecting cores, caches, memory and four 10 Gbps off-chip communication channels are harder to simulate tough.