> Did you know that you can’t write to video memory on the Game Boy Advance in units of 8 bits, and if you do, it’ll still work but all your graphics will be messed up with no obvious way to figure it out unless you read one specific paragraph of the documentation? Hey did you know that when you compile a binary optimized for size, memory copies will be by units of 8 bits, but not if you use debug mode?
Andrew (or any Zig mavens) -
What would be the idiomatic way of solving this issue? Can you define your own memcpy with @std.mem.doNotOptimizeAway or something?
Andrew’s point is that marking the memory as volatile should prevent this optimization. (i.e. the compiler isn’t allowed to split a 16-bit volatile write into two 8-but writes.) This is idiomatic because volatile is intended for MMIO.
There’s a proposal for a way to disable LLVM generating builtin calls like memcpy. But I’d argue volatile would still be more appropriate in this case.
Andrew (or any Zig mavens) - What would be the idiomatic way of solving this issue? Can you define your own memcpy with @std.mem.doNotOptimizeAway or something?