[terrymah]

No, we compile in bottom up order, starting with leaf functions, and collecting information about functions as we go. So "not throwing" sort of trickles up when possible to a certain degree.

In LTCG (MSVC)/O3 (GCC/Clang) there are prepasses over the entire callgraph to collect this order

[compiler-guy]

Yes of course. Sometimes the compiler can tell. But the original question feels to me more like “Shouldn't the compiler deduce restrict for you?”