On Thu, Feb 9, 2017 at 8:33 PM, Steve Kargl <s...@troutmask.apl.washington.edu> wrote: > On Thu, Feb 09, 2017 at 12:10:02PM +0200, Janne Blomqvist wrote: >> >> That being said, I think even with Steve's patch, it's not guaranteed >> to give you IEEE 754-2008 binary128. E.g. on IBM POWER targets, >> depending on the ABI you may get an IBM extended double (double-double >> or __ibm128) format. Although if IEEE binary128 is also available, >> with Steve's patch you should get that one has it has more precision >> that __ibm128. > > I do not have to a IBM POWER system, so cannot easily check the > effect of my patch.
Well, me neither. (And as I haven't heard back from Laurent Guerby wrt. access to the GCC compile farm, my charlen->size_t patch is stuck, and most likely won't make it to GCC 7. Gah!) > I, however, suspect that it has no effect, > because IBM POWER probably only supports REAL(4), REAL(8), and > REAL(16). REAL(16) can have either double-double or IEEE-754 > semantics, but not both. Hmm, I think you're right. Per https://gcc.gnu.org/wiki/Ieee128PowerPC it seems that powerpc defines IFmode and KFmode in addition to TFmode, where TFmode is an alias to IFmode or KFmode where the choice depends on various compile options, ABI defaults etc. And further, in trans-types.c:gfc_init_kinds we use TFmode only if we also use libquadmath (if TFmode is different from long double). So I guess on POWER REAL(16) will be whatever the C long double type maps to. >> >> - Is this appropriate for stage 4? >> >> >> > Now that you remind of it, if we take the rules to the letter, no. >> > My opinion is that it should be accepted, in stage 4 or later. >> > But I don’t have a strong opinion about it either. >> >> I think it's Ok, the patch is quite small and unlikely to cause >> regressions. In particular since the ABI has already been bumped, now >> is a good time to piggyback other ABI changing stuff. >> >> Steve, please don't revert, but add a note to gcc-7/changes.html and >> the GFortran wiki. > > I may have had acces to the wiki at some point, but no longer can > login. For the gcc-7/changes.html, is the attached diff ok? Maybe prepend something like "The practical effect of this change is that ..." to the second paragraph? > Gerald, > is there a ChangeLog for wwwdocs/? > > -- > Steve > 20161221 https://www.youtube.com/watch?v=IbCHE-hONow -- Janne Blomqvist
