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Re: pr11135: make PIC register a pseudo
- From: Rask Ingemann Lambertsen <rask at sygehus dot dk>
- To: Richard Henderson <rth at redhat dot com>, Ian Lance Taylor <ian at airs dot com>, Stuart Hastings <stuart at apple dot com>, gcc at gcc dot gnu dot org
- Date: Sun, 13 May 2007 12:32:21 +0200
- Subject: Re: pr11135: make PIC register a pseudo
- References: <4061F155-7B01-47B4-B4C5-56A82C2E9824@apple.com> <m3y81uxsju.fsf@gossamer.airs.com> <20060106224830.GA6328@redhat.com>
On Fri, Jan 06, 2006 at 02:48:30PM -0800, Richard Henderson wrote:
>
> What they're looking for is, for functions that don't use
> the pic register, to not reserve the pic register so that
> it's available for computation. This is harder. In theory,
> ppc has some scheme for this, where they eliminate the pic
> register to itself. I've never really understood how that's
> supposed to work.
Suppose you tell reload that %rpic can be eliminated as %rpic + 0. Reload
will start out by assuming that the elimination is possible and %rpic will
be available for reloads. If no insns mention %rpic at all, it should just
work, and you will have recovered a register.
--
Rask Ingemann Lambertsen