powerpc assembler: STW and .sdata variables

powerpc assembler: STW and .sdata variables

[Jeff Lasslett]

Hello,

The Diab assembler that I am replacing with GNU as supports the following:-

     stw     r3,Trace@sdarx(r13)

All it's doing is storing the contents of r3 into the variable 'Trace' which
happens to be in the .sdata section.

Is there a GNU equivalent to the diab syntax above?

'Trace' is a variable declared in section .sdata.

'@sdarx' is described as follows in the Diab assembler manual:-


	expr@sdarx	The 16 bit offset of expr from the SDA base register
			is calculated. The produced relocation will cause the
			linker to modify the destination register field in the
			instruction.

If I understand the EABI correctly then r13 should hold the base address of
the .sdata section.

Do I have to do something like:

	lis	r10,Trace@ha
	stw	r3,Trace@l(r10)

Or is there some syntax that makes use of the fact that a register (r13) has
the .sdata address in it already?

Thanks,

Jeff

Re: powerpc assembler: STW and .sdata variables

[Alan Modra]

On Thu, Sep 14, 2006 at 12:23:23PM +1000, Jeff Lasslett wrote:
> The Diab assembler that I am replacing with GNU as supports the following:-
> 
>     stw     r3,Trace@sdarx(r13)
> 
> All it's doing is storing the contents of r3 into the variable 'Trace' which
> happens to be in the .sdata section.
> 
> Is there a GNU equivalent to the diab syntax above?

     stw     %r3,Trace@sdarel(%r13)

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre