For all but the last pass the assembler only needs to count how much space
is needed for the machine code, it doesn't actually need to emit anything.
The dummy_data just uses unnecessary RAM and without it the code is not
any more complex (and code size does not increase for Thumb and Xtensa
archs).
If a port defines MP_PLAT_COMMIT_EXEC then this function is used to turn
RAM data into executable code. For example a port may want to write the
data to flash for execution. The function must return a pointer to the
executable data.
Scott Shawcroft
microDev
Diego Elio Pettenò
Damien George