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Re: builtin assembler constraints
On Fri, Feb 8, 2013 at 1:26 PM, Grobman Alexander-R53196
<R53196@freescale.com> wrote:
> This is really strange that such option does not exist. VLE instruction set does not use r8-r24 for many 16bit instructions. How do people use inline assembly with these? Or does compiler recognize these limitations for
"known" instructions by itself?
(Plesae don't top-post. Thanks.)
I don't know the PPC instruction set all that well. I don't know how
the VLE instructions work; I don't even know what they are. I can
tell you that GCC never recognizes instructions in an asm strings.
The valid set of registers for any argument are always expressed
through constraints.
Ian
> -----Original Message-----
> From: Ian Lance Taylor [mailto:iant@google.com]
> Sent: Friday, February 08, 2013 3:19 PM
> To: Grobman Alexander-R53196
> Cc: gcc-help@gcc.gnu.org
> Subject: Re: builtin assembler constraints
>
> On Fri, Feb 8, 2013 at 10:15 AM, Grobman Alexander-R53196 <R53196@freescale.com> wrote:
>>
>> I'm trying to incorporate new PPC instructions into a C code. These
>> instructions use limited set of GPRs as operands i.e. only even
>> registers can be used as a source,
>>
>> Is there way to specify that in the asm() statement?
>
> As far as I know there is no constraint that describes only the even registers of the general register set. It would not be very difficult to add one to the PPC backend. I can't think of any other way to approach this.
>
> Ian
>
>