[Icc-avr] Preserved registers?

[bobgardner at aol.com]

Only exception... maybe one of these programs is using r20,21,22,23 by accident when it shouldnt be?? 
 
-----Original Message-----
From: richard-lists at imagecraft.com
Sent: Wed, 4 Apr 2007 4:03 PM
Subject: Re: [Icc-avr] Preserved registers?


Is "foo" compiled by ICC? If so, then it should not be a problem, since foo()'s code will save/restore the "Preserved Registers" (see Help on Calling Convention and Assembler Interface). If foo() is written in assembler, it will still need to obey the convention. 
 
At 10:44 AM 4/4/2007, Peter LaDow wrote: 
>I'm running into an issue with preserved registers being overwritten. 
> 
>For example, I have something like: 
> 
>extern void (*foo)(void); 
> 
>void bar(void) 
>{ 
> int i; 
> 
> for(i=0; i < 16; i++) 
> { 
> foo(); 
> } 
>} 
> 
>The problem is that i keeps getting destroyed after a call to foo(). I've >tracked this down and it is because foo() is using the same registers that >i is using. Now foo() is not located in the same executable ( i.e. not >linked with bar()), and I think some sort of optimization is being >done. Since bar() is unaware of foo()'s register usage, and foo() is >unaware of bar()'s register usage, they can pick the same registers. 
> 
>(The application calls functions in the bootloader to program the flash, >but the bootloader and application are compiled separately.) 
> 
>I do NOT have global optimizations enabled (which I think is -Wf-O8). 
> 
>I think my only way to handle this is to make sure that all preserved >registers are saved and restored whenever leaving (or entering) code >outside of the current executable. Is this my only solution, or is there >an ICC way to handle this? 
> 
>Thanks, 
>Pete 
 
// richard (This email is for mailing lists. To reach me directly, please use richard at imagecraft.com)  
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