We are developing a product on 8051 microcontroller. We have done coding using assembly language. Right now our code size is very high and is overshooting the allocated ROM size.
We have started code optimization using “code optimizing tips†and by “optimizing the designâ€. But from “assembler and linker†I am unaware of any directive available for code optimization.
Please let me know for any tools/KEIL options which help in "Assembly code optimization" (Eg: Identifying repeated patterns, identifying duplicate expressions, removal of dead code, Suggesting right instruction etc…)
Please let me know for any tools/KEIL options which help in "Assembly code optimization"
I'm not aware of any such tools.
Usually, the point of writing code in assembly is to have the processor execute _exactly_ the instructions specified by the programmer, without giving the tools any freedom to make changes to the code.
Also, "highly optimized" assembly code is usually a nightmare to debug. If the code was produced by a compiler from a high-level language, it's easy to reduce the optimization level and check the un-optimized code for correct function, but it'd be hard to do that with "optimized" assembly.
However, if you are exceeding the "allocated ROM size" which was deemed enough for the project, then maybe you should start by optimizing the ("high level") program flow and the algorithms first, and _then_ look at the actual code again. Usually, this is easier and can bring more savings and less headaches than painstakingly sifting through already-written assembly and changing it without breaking the program.
So, why did you choose assembler?
As Christoph says, the whole point of writing in assembler is that you have complete and total control - which means that you must do any and all optimisation yourself!
If you want to delegate this to tools, then you will have to use a high-level language.
It is quite possible that a good optimising 'C' compiler and linker might produce "tighter" code than a novice assembler programmer, I think...
a novice assembler programmer may, indeed need to 'optimize' his assembly, a seasoned assembler programmer will automatically write optimum code (if he did not need optimum, he would use C).
conclusion: a novice assembler programmer has the same chance as a tailor in hell, a seasoned assembler programmer does not need to optimize, it is already dome.
sure, a seasoned assembler programmer can, occasionally, squeeze a few bytes or a few microseconds out by reviewing his code, but that would be a nominal gain.
anyhow, if the OP would show some code it could be judged if any particular method is suboptimum
Erik