On Wed, Oct 25, 2017 at 07:11:07PM -0500, Segher Boessenkool wrote: > Hi Mike, > > On Sat, Oct 21, 2017 at 09:09:58AM -0400, Michael Meissner wrote: > > As Segher and I were discussing off-line, I have some problems with the > > current > > -mabi={ieee,ibm}longdouble switches as we start to planning to modify GCC 9 > > and > > GLIBC 2.27/2.28 to support __float128 as the default long double format for > > power server systems. > > > > My gripes are: > > > > 1) Using Warn() in rs6000.opt means that you get two warning > > messages when > > you use the switches (one from the driver, and one from cc1). > > > > 2) I feel you should not get a warning if you select the option > > that > > reflects the current default behavior (i.e. -mabi=ibmlongdouble > > currently for power server systems). > > > > 3) There is no way to silenece the warning (i.e. -w doesn't work on > > warnings in the .opt file). Both GLIBC and LIBGCC will need the > > ability to build support modules with an explicit long double format. > > > > 4) In the future we will need a little more flexibility in how the > > default > > is set. > > > > 5) There is a mis-match between the documentation and rs6000.opt, > > as these > > switches are documented, but use Undocumented in the rs6000.opt. > > Agreed on all. > > > These patches fix these issues. If you use -Wno-psabi, it will silence the > > warning. I have built these patches on a little endian power8 system, and > > there were no regressions. Can I check these patches into the trunk? > > > > 2017-10-21 Michael Meissner <meiss...@linux.vnet.ibm.com> > > > > * config/rs6000/aix.h (TARGET_IEEEQUAD_DEFAULT): Set long double > > default to IBM. > > * config/rs6000/darwin.h (TARGET_IEEEQUAD_DEFAULT): Likewise. > > * config/rs6000/rs6000.opt (-mabi=ieeelongdouble): Move the > > warning to rs6000.c. Remove the Undocumented flag, since it has > > been documented. > > (-mabi=ibmlongdouble): Likewise. > > And more importantly, we _want_ it to be documented (right)?
I would have preferred to not document it until GCC 9 when we start the switch to long double == _Float128, but since it was already documented (albeit only for 32 bit), I kept it documented. If you want me to change it to undocumented, I can do that. > > --- gcc/config/rs6000/rs6000.opt (revision 253961) > > +++ gcc/config/rs6000/rs6000.opt (working copy) > > @@ -381,10 +381,10 @@ mabi=d32 > > Target RejectNegative Undocumented Warn(using old darwin ABI) > > Var(rs6000_darwin64_abi, 0) > > > > mabi=ieeelongdouble > > -Target RejectNegative Undocumented Warn(using IEEE extended precision long > > double) Var(rs6000_ieeequad) Save > > +Target RejectNegative Var(rs6000_ieeequad) Save > > > > mabi=ibmlongdouble > > -Target RejectNegative Undocumented Warn(using IBM extended precision long > > double) Var(rs6000_ieeequad, 0) > > +Target RejectNegative Var(rs6000_ieeequad, 0) > > Does this need "Save" as well? No for variables, you want Save on the first instance only. > > + if (!warned_change_long_double && warn_psabi) > > + { > > + warned_change_long_double = true; > > + if (TARGET_IEEEQUAD) > > + warning (0, "Using IEEE extended precision long double"); > > + else > > + warning (0, "Using IBM extended precision long double"); > > + } > > You can put OPT_Wpsabi in place of that 0, it's what that arg is for :-) Ah, ok. Thanks. > Okay with that changed. Thanks! > > > Segher > -- Michael Meissner, IBM IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA email: meiss...@linux.vnet.ibm.com, phone: +1 (978) 899-4797