All ports that enable LTO by default either downstream (port option) or upstream are broken on riscv64. During build object files are built with -mabi=lp64d (hard float) but linking happens with implicit -mabi=lp64 (soft float). LTO postpones optimization until linking, so ABI must match. https://lists.freebsd.org/archives/dev-commits-ports-main/2021-October/002774.html