After having spent about a decade of aggressively optimising C/C++ code, the speaker would like to share his view on modern compilers, why C isn't a portable assembler anymore and why some people have a rather radical belief that optimising compilers are dead. After having spent about a decade of aggressively optimising C/C++ code, the speaker would like to share his view on modern compilers, why C isn't a portable assembler anymore and why some people have a rather radical belief that optimising compilers are dead. The speaker will demonstrate several simple C programs that get compiled to native code with surprising results including now famous "rm -rf /" executed from an unreachable function. These and other similar programs cause a friction in programming and infosec communities. While people are mostly concerned with unpredictable artefacts of undefined behaviour in C/C++ languages, there are also performance considerations. Finally, the speaker will briefly look at other languages and check if they do any better.