zlacker

[return to "Std: Clamp generates less efficient assembly than std:min(max,std:max(min,v))"]
◧
1. tambre+2i[view] [source] 2024-01-16 13:21:16
>>x1f604+(OP)
Both recent GCC and Clang are able to generate the most optimal version for std::clamp() if you add something like -march=znver1, even at -O1 [0]. Interesting!

[0] https://godbolt.org/z/YsMMo7Kjz

◧◩
2. Grumpy+Wk[view] [source] 2024-01-16 13:41:52
>>tambre+2i
But then it uses AVX instructions. (You can replace -march=znver1 with just -mavx.)

When AVX isn’t enabled, the std::min + std::max example still uses fewer instructions. Looks like a random register allocation failure.

[go to top]