[PING^3] Make ARM use UNSPECs instead of complicated CONSTs

[PING^3] Make ARM use UNSPECs instead of complicated CONSTs

[Richard Sandiford]

http://gcc.gnu.org/ml/gcc-patches/2008-10/msg00456.html
Fixes what I think is the last example of (const minus) being used
by a port.  Please review, since the fix for PR37363 depends on it.

Richard

Re: [PING^3] Make ARM use UNSPECs instead of complicated CONSTs

[Michael Meissner]

On Tue, Oct 28, 2008 at 10:30:08PM +0000, Richard Sandiford wrote:
> http://gcc.gnu.org/ml/gcc-patches/2008-10/msg00456.html
> Fixes what I think is the last example of (const minus) being used
> by a port.  Please review, since the fix for PR37363 depends on it.
> 
> Richard

I took a look at this, and I wonder why you don't see an insn not found message
for the change in arm.c to build the pic_rtx register with UNSPEC_GOTSYM_OFF,
since I don't see any insns that use UNSPEC_GOTSYM_OFF.

-- 
Michael Meissner, IBM
4 Technology Place Drive, MS 2203A, Westford, MA, 01886, USA
meissner@linux.vnet.ibm.com

Re: [PING^3] Make ARM use UNSPECs instead of complicated CONSTs

[Richard Sandiford]

Hi Mike,

Thanks for taking a look.

Michael Meissner <meissner@linux.vnet.ibm.com> writes:
> On Tue, Oct 28, 2008 at 10:30:08PM +0000, Richard Sandiford wrote:
>> http://gcc.gnu.org/ml/gcc-patches/2008-10/msg00456.html
>> Fixes what I think is the last example of (const minus) being used
>> by a port.  Please review, since the fix for PR37363 depends on it.
>> 
>> Richard
>
> I took a look at this, and I wonder why you don't see an insn not
> found message for the change in arm.c to build the pic_rtx register
> with UNSPEC_GOTSYM_OFF, since I don't see any insns that use
> UNSPEC_GOTSYM_OFF.

The idea is that the UNSPEC_GOTSYM_OFF is wrapped in a CONST, just like
the original MINUS expression was.  Both the old and new forms satisfy
immediate_operand, so the SET matches the normal move insns.

As it happens, Paul recently approved the patch in the original thread
(thanks) so I've since applied it.  But like I say, thanks for looking
at the patch, and for raising your concerns.

Richard