#306 RIP-relative addressing not supported

[MazeGen]

I'm surprised that JWasm doesn't support explicit RIP-relative addressing. I know that MASM doesn't support it as well. I'm sure there is a number of specific projects that need this addressing. And it should be easy to add.

Example: (compile with jwasm -win64)

.code
lea rax, [rip]
end

Error A2102: Symbol not defined : rip