[userbinator]

Intel sells a compiler. I've only used it briefly a long time ago, but its code generation was well ahead of MSVC at the time even for scalar (non-SIMD) stuff, and I remember GCC was far behind too (it would generate roughly the same performance in microbenchmarks, but far more bloated.)

[bee_rider]

Intel has released at least some of their software suite for free (as in beer, not as in speech).

https://www.intel.com/content/www/us/en/developer/articles/n...

I think software is not a huge profit center for them.

The original comment presents:

> The actual details there are [1] too secret for Intel to want to accurately describe them in gcc, [2] they’re different across different CPUs, [3] and compilers just aren’t as good as you think they are.

2 and 3 could just be the whole story. Although we haven't actually accumulated any evidence here for 3, given that the original story was about surprisingly getting beat by a compiler, despite performing a seemingly obvious optimization.

[astrange]

You can just look at gcc and llvm source. GCC’s x86 backend is maintained by an Intel employee and it doesn’t have especially detailed descriptions of any cpu in -mtune.

Actually, compiler optimizations like scheduling tend to be neutral to negative on x86 because they increase register pressure. You’d probably want to do “anti-scheduling” and hope the CPU decoder takes care of it if anything.

[projektfu]

https://en.wikipedia.org/wiki/Intel_C%2B%2B_Compiler

Interesting that it generates suboptimal code for non-Intel processors.