On 7/27/17 1:33 PM, Adrian Matoga wrote:
Why can't we just make the compiler insert null checks in @safe code? We can afford bounds checking even in @system -O -release. C++ can afford null check upon executing an std::function. The pointer would most likely be in a register anyway, and the conditional branch would almost always not be taken, so the cost of that check would be barely measurable. Moreover, the compiler can elide the check e.g. if the access via pointer is made in a loop in which the pointer doesn't change. And if you prove that this tiny little check ruins performance of your code, there's @trusted to help you.
The rationale from Walter has always been that the hardware is already doing this for us. I was always under the assumption that D only supported environments/systems where this happens. But technically there's nothing in the spec to require it. And it does seem apparent that we handle this situation.
This question/query is asking whether we should amend the spec with (what I think is) Walter's view, or if we should change the compiler to insert the checks.
-Steve
