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

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inline asm: How to push PIC reg before seven in...
\ lynx.abraxas (24 Mar 2007)
. \ Andrew Haley (24 Mar 2007)
. . \ lynx.abraxas (24 Mar 2007)
. . . \ Andrew Haley (24 Mar 2007)
. . . . \ lynx.abraxas (24 Mar 2007)
. . . . . \ Andrew Haley (24 Mar 2007)
. . . . . . \ lynx.abraxas (24 Mar 2007)
. . . . . . . \ Andrew Haley (25 Mar 2007)
. \ Timothy C Prince (24 Mar 2007)

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Subject:	Re: inline asm: How to push PIC reg before seven input operands get loaded?
Group:	Gcc-help
From:	Andrew Haley
Date:	25 Mar 2007

lynx.abraxas writes:
> On 24/03/07 20:42:02, Andrew Haley wrote:
>
> Is there then an option to gcc that lets gcc push all registers before asm so
> that I can use what I need without having to hope gcc lets me use all
> registers?

No.

> > > But if I specified "b" it complains about: error: PIC register
> > > %ebx clobbered in asm
> > >
> > > Is this a bug in gcc??? Is there a constraint just for ebp so I
> > > don't have to use "R" and hope it gets into ebp?
> >
> > Why do you care that it is in ebp? Why do you not allow gcc to choose
> > the register? You seem to want to use explicit registers in your asm,
> > but I can't see any reason why you want to do that. gcc usually works
> > better when you let gcc choose the registers.
>
> I tried with just "r". But then gcc complains about not enough
> registers as it seems not wanting to use ebp and it still doesn't
> want to give up on ebx for PIC.

Please, give us a test case.

> Another reason is I don't know how to specify a register in the asm
> code that is still empty. Like in my problem I need at least one
> empty register apart the six preloaded ones. I use ebx there, so I
> can circumvent the PIC problem. Is there a way to specify an empty
> register without a direct name?

Sure, you just need to use an input/ouput register operand. It's in
the docs.

> And %dx I use because there is no way mentioned in the docs how to
> reduce the size when using eg %3.

How to reduce the size of what? This doesn't make any sense to me.
Please, give us a test case.

Andrew.