In practice, <asterisk>(int <asterisk>)0 (how do I escape asterisks on HN?) and similar are popular idioms for "segfault here". Making them break is not an optimization any compiler maintainer would bother to make - it requires a special case and there don't seem to be any benefits to justify the effort.

See the series of articles starting with http://blog.llvm.org/2011/05/what-every-c-programmer-should-...

In practice: compilers usually don't touch expressions with volatile vars.