Chris Brooks wrote:

"I think the problem may also come down to treating programming using C on a microcontroller like you were using C on a PC..."

Actually, I think you identified the fundamental problem when you said:

"I suggest reading the manual that comes with SDCC"

This whole spate of SDCC questions seems to come from someone who has neglected this basic discipline! :-(

You cannot hope to use a compiler effectively, and understand the results, unless you Read The Manual!!!