Does a compiler use all x86 instructions? (2010)
My question is if compilers use "new" x86 instructions, as then the program won't work <i>at all</i> on old systems.<p>For example, if Intel decided today that CPUs need a new "fast" hashing opcode (I don't know if they actually do),  a compiler can't compiles to it, as programs won't work on older computers.<p>Is it like the API cruft in Android, where "new" Lollipop APIs are introduced for 10 years from now, when no one uses any phones from before 2014?