[Bug middle-end/19779] IBM 128bit long double format is not constant folded.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19779 --- Comment #13 from Jakub Jelinek --- Nobody is blocking proper double double evaluation support. But somebody needs to do the work, spend a few weeks on it and submit that. I'm just saying that is highly unlikely. If somebody was really bothered about that there wouldn't be 19 years of it being unfixed. More so in the years when it was the typical long double on Linux powerpc64le as well. It is still the usually supported long double on Linux powerpc64 and powerpc, but those are rarely used these days.
[Bug middle-end/19779] IBM 128bit long double format is not constant folded.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19779 --- Comment #12 from Jonathan Wakely --- Then the maintainers or users of those targets should consider contributing a fix.
[Bug middle-end/19779] IBM 128bit long double format is not constant folded.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19779 --- Comment #11 from Sergey Fedorov --- (In reply to Jakub Jelinek from comment #7) > Unlikely to be ever fixed, at least Linux has migrated to IEEE quad long > double on powerpc64le. Perhaps several *BSDs and AIX are using IBM format though.
[Bug middle-end/19779] IBM 128bit long double format is not constant folded.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19779 --- Comment #10 from Jakub Jelinek --- (In reply to Iain Sandoe from comment #9) > (In reply to Andrew Pinski from comment #8) > > (In reply to Sergey Fedorov from comment #6) > > > (In reply to Andrew Pinski from comment #0) > > > > This is the new bug for PR 19405. Keeping track of that we no longer > > > > constant fold long doubles in the > > > > IBM 128bit long double format. > > > > > > What is the current status of the issue? > > > > Nothing has changed here that much. Though powerpc64 le is heading towards > > doing IEEE 128bit FP by default so this might be much much less of an issue > > for most people which means this is more likely never get fixed. > > it occasionally causes grief, but so far there's been a work-around; I guess > if someone really wanted to make a patch - they'd have to use MPFR et. al. > to do the work. MPFR won't really help, after all, it doesn't have any double double arithmetic support at all. The problem is that real.cc pretends that IBM double double is a sane floating point format with 106bit precision, which is not the case. In GCC, basic floating point operations are performed by performing stuff in the GCC internal format, which is something with sufficient precision and exponent range to cover all the sane supported formats including some extra precision bits and then converting that to the appropriate mode. That doesn't work for double double, which has precision between 53 to some thousands bits of precision, so in order to emulate in the compiler basic floating point, it would need to be handled like it is actually at runtime, which is hold the REAL_CST/CONST_DOUBLE double double values as a pair of DFmode values rather than a single real_internal_format value (because the latter can't express all the double double values), perform whatever __gcc_qadd/__gcc_qsub/__gcc_qmul/__gcc_qdiv etc. perform at runtime on the DFmode values, etc. And then there is a question what to do about emulation of libm functions - how to map that e.g. to mpfr operations, because what libm actually does for those is sometimes quite weird and hard to define.
[Bug middle-end/19779] IBM 128bit long double format is not constant folded.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19779 --- Comment #9 from Iain Sandoe --- (In reply to Andrew Pinski from comment #8) > (In reply to Sergey Fedorov from comment #6) > > (In reply to Andrew Pinski from comment #0) > > > This is the new bug for PR 19405. Keeping track of that we no longer > > > constant fold long doubles in the > > > IBM 128bit long double format. > > > > What is the current status of the issue? > > Nothing has changed here that much. Though powerpc64 le is heading towards > doing IEEE 128bit FP by default so this might be much much less of an issue > for most people which means this is more likely never get fixed. it occasionally causes grief, but so far there's been a work-around; I guess if someone really wanted to make a patch - they'd have to use MPFR et. al. to do the work.
[Bug middle-end/19779] IBM 128bit long double format is not constant folded.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19779 --- Comment #8 from Andrew Pinski --- (In reply to Sergey Fedorov from comment #6) > (In reply to Andrew Pinski from comment #0) > > This is the new bug for PR 19405. Keeping track of that we no longer > > constant fold long doubles in the > > IBM 128bit long double format. > > What is the current status of the issue? Nothing has changed here that much. Though powerpc64 le is heading towards doing IEEE 128bit FP by default so this might be much much less of an issue for most people which means this is more likely never get fixed.
[Bug middle-end/19779] IBM 128bit long double format is not constant folded.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19779 --- Comment #7 from Jakub Jelinek --- Unlikely to be ever fixed, at least Linux has migrated to IEEE quad long double on powerpc64le.
[Bug middle-end/19779] IBM 128bit long double format is not constant folded.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19779 --- Comment #6 from Sergey Fedorov --- (In reply to Andrew Pinski from comment #0) > This is the new bug for PR 19405. Keeping track of that we no longer > constant fold long doubles in the > IBM 128bit long double format. What is the current status of the issue?
[Bug middle-end/19779] IBM 128bit long double format is not constant folded.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19779 Andrew Pinski changed: What|Removed |Added CC||Sebastian at SSpaeth dot de --- Comment #5 from Andrew Pinski --- *** Bug 107745 has been marked as a duplicate of this bug. ***
[Bug middle-end/19779] IBM 128bit long double format is not constant folded.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19779 Andrew Pinski changed: What|Removed |Added CC||liushuyu011 at gmail dot com --- Comment #4 from Andrew Pinski --- *** Bug 105578 has been marked as a duplicate of this bug. ***
[Bug middle-end/19779] IBM 128bit long double format is not constant folded.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19779 --- Comment #3 from Jonathan Wakely --- Yeah, I'm not asking for it to be fixed, just noting here that it affects C++ constant expressions.
[Bug middle-end/19779] IBM 128bit long double format is not constant folded.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19779 Jakub Jelinek changed: What|Removed |Added CC||jakub at gcc dot gnu.org --- Comment #2 from Jakub Jelinek --- We do fold it with -ffast-math or -funsafe-math-optimizations. PR19405 explains the reasons why we can't fold those results that aren't exactly representable in double double.
[Bug middle-end/19779] IBM 128bit long double format is not constant folded.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19779 Jonathan Wakely changed: What|Removed |Added CC||redi at gcc dot gnu.org --- Comment #1 from Jonathan Wakely --- I think this should be rejects-valid not a missed-optimization enhancement. For C++20 we reject valid code: #include constexpr long double x = 1.0L + std::numeric_limits::epsilon(); :1:32: error: ‘(1.0e+0l + 4.94065645841246544176568792868221e-324l)’ is not a constant expression The code reduces to: constexpr long double x = 1.0L + __LDBL_EPSILON__;
[Bug middle-end/19779] IBM 128bit long double format is not constant folded.
-- What|Removed |Added Status|UNCONFIRMED |NEW Ever Confirmed||1 Last reconfirmed|-00-00 00:00:00 |2005-02-20 14:18:49 date|| http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19779
[Bug middle-end/19779] IBM 128bit long double format is not constant folded.
-- What|Removed |Added Summary|IBM 128bit long double |IBM 128bit long double |format is not constant |format is not constant |foldded.|folded. http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19779
