Processor cache

Hi /prog/,
The people who write high-perforance stuff must use a lot of tricks like putting the data in a continuous chunk of memory and splitting your program by what is done with your data instead of what is your data. Now, all these tricks are used to make sure you don't get a cache miss, but couldn't they be considered premature optimization?

What if the cpu let us specify what should be put in its cache; then compilers could automatically manage this, and people who needs extreme performance would have more control over the cache.

Thanks

I want to know if there is an obvious reason why we are not allowed to put data manually in the cache*