tooling quality and some random rant

[Walter Bright]

retard wrote:
 > There are no arch specific optimizations for PIII, Pentium 4, Pentium D,
Core, Core 2, Core i7, Core i7 2600K, and similar kinds of products from
AMD.

The optimal instruction sequences varied dramatically on those earlier 
processors, but not so much at all on the later ones. Reading the latest 
Intel/AMD instruction set references doesn't even provide that information anymore.

In particular, instruction scheduling no longer seems to matter, except for the 
Intel Atom, which benefits very much from Pentium style instruction scheduling. 
Ironically, dmc++ is the only available current compiler which supports that.


> No mention of auto-vectorization 

dmc doesn't do auto-vectorization. I agree that's an issue.


 > or whole program

I looked into that, there's not a lot of oil in that well.


 > and instruction level optimizations the very latest GCC and LLVM are now 
slowly adopting.

Huh? Every compiler in existence has done, and always has done, instruction 
level optimizations.


Note: a lot of modern compilers expend tremendous effort optimizing access to 
global variables (often screwing up multithreaded code in the process). I've 
always viewed this as a crock, since modern programming style eschews globals as 
much as possible.