Re: inline asm: How to push PIC reg before seven input operands get loaded?

[lynx dot abraxas at freenet dot de]

On 24/03/07 11:11:52, Andrew Haley wrote:
>  > I got a bit further with my problem. Now I'm stuck on how to save
>  > the register used when -fPIC is enabled to the stack before my
>  > seven input operands, needing all registers, get loaded. Is that
>  > somehow possible? I couldn't find any examples on the net. It seems
>  > not to be necessary in the original code for MSC.
> 
> I doubt very much thath is possible.

Thanks for Your answer. I then wonder why gcc doesn't let me load the registers from the memory myself. 
If I do eg:

Pixel16 *tileData[4]; uint16 *pDestPixel; Pixel16 *dataPtr, *transDataPtr;
sint32 startX, endX;
__asm__ __volatile__ (
"push %%ebx     \n\t"  // save reg for PIC!
//code here using %1 but now reg can be rused:

"movl %5, %1            \n\t" //no reg left for %5 when gcc should handel it
                              //but now gcc says: 
                              //error: memory input 5 is not directly addressable
"movl (%1,%%ebx,4), %1 \n\t"  //instead of "movl (%5,%%ebx,4), %1 \n\t" 
                              //because m for %5 didn't work here

//more code using also ebx and ebp
"pop %%ebx     \n\t" // restore reg for PIC!
:
: "D" (pDestPixel), "d" (endX), "c" (startX), "a" (transDataPtr), "S" (dataPtr), "m" (tileData)
: "cc" //don't tell gcc about what was done to ebx because of PIC!!!
);

gcc complains about: error: memory input 5 is not directly addressable
Why is that? How else should I load the tileData pointer from memory into a register?

>  > Also I wonder which -f option that comes with -O2 makes gcc stop reporting:
>  > error: can't find a register in class 'LEGACY_REGS' while reloading 'asm'
> 
> I guess this is a joke.

No, it isn't. I wouldn't have asked else wise...
Is it the combination of all -f options in -O2? I coudn't find a single obviouse one in the manpage.
Is it a rule then to include -O2 or higher if inline asm is used???

> 
> Andrew.

Thanks Andrew.
Lynx