another thing a compiler cant do is what it cant know
like when you know a loop will only execute 3-7 times
a compiler dosent know that so it will put out a speed optimized version, one that is bloated for what it does
also i never said you have to write whole programs in assembly too get performance
on the contrary i said you are best to write only few tightest loops in assembly
also can you show me a program more optimized then x264 or glibc ?
benchmark the pure C version of musl against glibc then you can say for sure how good a compiler is
musl from what i see is good, optimized, C so perfect for benchmarks