tooling quality and some random rant

[Walter Bright]

Don wrote:
> In hand-coded asm, instruction scheduling still gives more than half of 
> the same benefit that it used to do. But, it's become ten times more 
> difficult. You have to use Agner Fog's manuals, not Intel/AMD.
> 
> For example:
> (1) a common bottleneck on all Intel processors, is that you can only 
> read from three registers per cycle, but you can also read from any 
> register which has been modified in the last three cycles.
> (2) it's important to break dependency chains.
> 
> On the BigInt code, instruction scheduling gave a speedup of ~40%.

Wow. I didn't know that. Do any compilers currently schedule this stuff?

Any chance you want to take a look at cgsched.c? I had great success using the 
same algorithm for the quite different Pentium and P6 scheduling minutia.