Earlier quoted context omitted.
Arguing about icache utilization is a little silly here - the code will be laid out for you as though the branches are not taken (or you should force it to do so). In that case, the only "waste" of icache is the CMP and JMP, an additional 4-8 bytes per return, and literally 0 cycles. When you do take an error, each RET takes you 1 cycle, plus the 10-15 cycle mispredict for the CMP+JMP because there's a stack engine i…
The checks you're talking about are duplicated more or less per statement in some types of code. Every single call site ends up with an `if err != nil` or moral equivalent. It can add up, also consider the extra register pressure. The return values aren't valuable anymore, they're just error signalling. The compiler doesn't necessarily know what your error types are, it can try to use heuristics to move those blocks…
There is obviously a sparsity of exceptional cases where error-handling code like this is worse than using exceptions. I would claim that it's a lot more sparse than you think. Many people use exceptions for things like "file not found" or "function failed for whatever reason," (my favorite) "timeout," or "bad input from the user." These cases are often not that exceptional!