Per,

It is perfectly valid to inspect compiler generated code, especially if you are worried about the optimal efficiency of a sequence.

You might also inspect in order to pick up some tips for ASM techniques.

However most applications are not that critical. For example reading or writing a 93c66 chip is not going to make much difference. You will be dependent on the 8051's SPI peripheral and the speed of SCK clock.

Other applications might involve a lot of bit-bashing where the SPI chip is capable of faster speeds than the 8051. I still reckon that a reliable algorithm is the key. It is wise to make use of prior knowledge, especially if manufacturers offer proven methods.

You simply tweak if required. Keil is very good at code generation. SDCC sometimes needs some help. Very occasionally, both may benefit from a short hand-made ASM sequence.

I get the feeling that some people had to write every opcode themselves in their youth, and think that no one should benefit from available app notes, text books, example code ...

It is the skill to research and digest the available information that is important. Otherwise General Motors has to reinvent the wheel for each new model instead of developing from their existing products.

David.