This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: [PATCH, ifcvt] Allow CC mode if HAVE_cbranchcc4 (fix s390 build)
- From: "Ulrich Weigand" <uweigand at de dot ibm dot com>
- To: rth at redhat dot com (Richard Henderson)
- Cc: zhenqiang dot chen at arm dot com (Zhenqiang Chen), jbglaw at lug-owl dot de ('Jan-Benedict Glaw'), hpenner at de dot ibm dot com (Hartmut Penner), Andreas dot Krebbel at de dot ibm dot com (Andreas Krebbel), gcc-patches at gcc dot gnu dot org
- Date: Thu, 6 Nov 2014 17:10:48 +0100 (CET)
- Subject: Re: [PATCH, ifcvt] Allow CC mode if HAVE_cbranchcc4 (fix s390 build)
- Authentication-results: sourceware.org; auth=none
Richard Henderson wrote:
> On 11/06/2014 08:44 AM, Zhenqiang Chen wrote:
> > Hi,
> >
> > The patch add runtime check to fix s390 build fail
> > (https://gcc.gnu.org/ml/gcc-patches/2014-11/msg00050.html).
> >
> > And there is additional code to workaround s390 cstorecc4 issue.
> >
> > Bootstrap and no make check regression on X86-64.
> > Build s390-linux-gnu and s390x-linux-gnu.
> >
> > I do not have env to run full s390 tests. Would anyone in the TO list help
> > to run the s390 tests?
> >
> > Thanks!
> > -Zhenqiang
> >
> > ChangeLog:
> > 2014-11-06 Zhenqiang Chen <zhenqiang.chen@arm.com>
> >
> > * ifcvt.c (noce_emit_cmove, noce_get_alt_condition,
> > noce_get_condition):
> > Allow CC mode if HAVE_cbranchcc4.
> > (noce_emit_store_flag): Change CC REG as cond_complex.
> >
> > diff --git a/gcc/ifcvt.c b/gcc/ifcvt.c
> > index f4002f9..7f7b7c1 100644
> > --- a/gcc/ifcvt.c
> > +++ b/gcc/ifcvt.c
> > @@ -849,7 +849,10 @@ noce_emit_store_flag (struct noce_if_info *if_info, rtx
> > x, int reversep,
> > enum rtx_code code;
> >
> > cond_complex = (! general_operand (XEXP (cond, 0), VOIDmode)
> > - || ! general_operand (XEXP (cond, 1), VOIDmode));
> > + || ! general_operand (XEXP (cond, 1), VOIDmode)
> > + /* For s390, CC REG is general_operand. But cstorecc4
> > only
> > + handles CCZ1, which can not handle others like CCU.
> > */
> > + || GET_MODE_CLASS (GET_MODE (XEXP (cond, 0))) == MODE_CC);
> >
>
> I'd like to know more about this. This seems like a mistake in the backend.
We do indeed allow the CC register as general_operand, since it has a
register class of CC_REGS. This has been in place for over 10 years now
and was a deliberate decision to allow for pseudos that carry a condition
value to be allocated to the actual CC register or some GPR, depending on
reload's choices. As long as moves and (secondary) reloads are fully
supported (and they should be), this should be OK ...
Zhenqiang, what specific problem are you seeing?
Bye,
Ulrich
--
Dr. Ulrich Weigand
GNU/Linux compilers and toolchain
Ulrich.Weigand@de.ibm.com