Relief for retpoline pain
Relief for retpoline pain
Posted Dec 15, 2018 9:55 UTC (Sat) by ibukanov (subscriber, #3942)In reply to: Relief for retpoline pain by pbonzini
Parent article: Relief for retpoline pain
It was not only dynamic languages. Some compilers for object-oriented languages replace virtual calls by few ifs that check for all known classes and call the corresponding method statically. This was done, for example, in SmallEiffel compiler 20 years ago.
The indirect branch prediction on CPU made that optimization largely unnecessary, but now we are back to it as the prediction turned out to be a security nightmare.
Posted Dec 15, 2018 19:32 UTC (Sat)
by jcm (subscriber, #18262)
[Link]
Relief for retpoline pain
* The implemention turned out to be a nightmare, not the concept. It's ok to speculate into branches, you just need to tag the BTB with enough disambiguating context.