Andrei Alexandrescu needs to read this

Walter Bright newshound2 at
Wed Oct 23 23:22:08 UTC 2019

On 10/23/2019 3:03 PM, Jonathan Marler wrote:
> What I find funny is that there are alot of clever tricks you can do to make 
> your code execute less operations, but with modern CPUs it's more about making 
> your code more predictable so that the cache can predict what to load next and 
> which branches you're more likely to take.  So in a way, as CPUs get smarter, 
> you want to make your code "dumber" (i.e . more predictable) in order to get the 
> best performance.  When hardware was "dumber", it was better to make your code 
> smarter.  An odd switch in paradigms.

Keep in mind that starting in the late 70's, CPUs started being designed around 
the way compilers generate code. (Before then, instruction sets were a wacky 
collection of seemingly unrelated instructions. Compilers like orthogonality, 
and specialized instructions to do things like stack frame setup / teardown.)

This means that unusual instruction sequences tend to perform less well than the 
ordinary stuff a compiler generates.

It's also true that code optimizers are tuned to what the local C/C++ compiler 
generates, even if the optimizer is designed to work with multiple diverse 

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