I recall doing some Gentoo installs using -Os at least for some packages, just to see how much that would shrink binary sizes. Documentation / wikis etc. advis

I recall doing some Gentoo installs using -Os at least for some packages, just to see how much that would shrink binary sizes. Documentation / wikis etc. advised against that not just for performance-of-generated-code reasons, but also because of compiler bugs using -Os was considered unreliable. Note this was with ancient GCC (v2.9.x, early 3.x releases iirc)