What about performance overheads? I think the reason a lot of people write C is that they have direct control over the generated assembly to maximise performance.
Even direct control over the generated assembly (C does not provide this; only writing assembler does, and only if you don't do things like LTO) is not sufficient.
Modern CPUs do all sorts of weird things. Assembly instructions can be executed out of order. Your conditional jump instruction can be speculatively executed before the condition's truth is known. Fetches from main memory can be reordered.
Even more wildly, copying the contents of one register to another is often a no-op. Yes, that's right; the following code:
mov edx, eax
... does next to nothing on some modern CPUs. All it does sometimes is set an internal note to the effect of "later references to edx should read/write eax instead", until that note is cleared by some other operation.
You can write your assembler with the best of intentions as to how it should behave, only to discover that the CPU does things entirely differently. You still end up getting the same observable result out of it, but any timing and order of operation guarantees went out the window decades ago.
Modern CPUs do all sorts of weird things. Assembly instructions can be executed out of order. Your conditional jump instruction can be speculatively executed before the condition's truth is known. Fetches from main memory can be reordered.
Even more wildly, copying the contents of one register to another is often a no-op. Yes, that's right; the following code:
... does next to nothing on some modern CPUs. All it does sometimes is set an internal note to the effect of "later references to edx should read/write eax instead", until that note is cleared by some other operation.You can write your assembler with the best of intentions as to how it should behave, only to discover that the CPU does things entirely differently. You still end up getting the same observable result out of it, but any timing and order of operation guarantees went out the window decades ago.