CodeWarrior for MCUのトピックRe: C code not generating correct assembly

C code not generating correct assembly

ScottC — Mon, 24 Apr 2006 23:04:28 GMT

I am using CW and noticed code that I wrote to set a variable is being ignored, sometimes. I looked at the assemly listing. '08ap32

Any ideas?

Re: C code not generating correct assembly

J2MEJediMaster — Tue, 25 Apr 2006 02:11:58 GMT

It would help to have a look at your code and know what optimization level you're using with the compiler. When generating highly optimized code, the compiler may interpret some code is being run once and can be optimized out of existence.

---Tom

Re: C code not generating correct assembly

ScottC — Tue, 25 Apr 2006 04:46:49 GMT

I am just setting a global variable. In one section of the code it is ignored. In another, the code in the listing file is as it should be.

It happens to be ignored in the same in the same routine when set at different times.

How do I check optimization settings?

Message Edited by Scott C on 04-24-200604:47 PM

Message Edited by Scott C on 04-24-200604:53 PM

Message Edited by Scott C on 04-24-200604:54 PM

Re: C code not generating correct assembly

CrasyCat — Tue, 25 Apr 2006 16:22:26 GMT

Hello

Basically the compiler is optimizing access to global variables. If you have something like

var = 4;

var = 5;

the compiler will only generate code to assign 5 to var.

To make sure the compiler does not optimize access to a variable, define it as volatile.

CrasyCat

Re: C code not generating correct assembly

ScottC — Tue, 25 Apr 2006 20:01:27 GMT

I just define it to pass to another routine, but I will give it a try.

Thanks