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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/95450] [10/11 regression] Wrong long double folding Date: Tue, 11 Aug 2020 16:19:04 +0000 [thread overview] Message-ID: <bug-95450-4-oIAZAAZ2GE@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-95450-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95450 --- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> --- The problem is that this gl_LDBL_MAX.ld is really the right maximum normalized double double number, but is one ulp larger than GCC's __LDBL_MAX__. The former is: 0x1.fffffffffffff7ffffffffffffc000p+1023 and the latter is: 0x1.fffffffffffff7ffffffffffff8000p+1023 The reason why gcc doesn't like the former and will treat it as infinity is that GCC internally treats the double double as having a 106 bit precision, but the former number is too large for 106 bit precision, it requires 107 bit precision. If we'd want to handle double double "properly" in GCC, we'd need to emulate it the way it is actually implemented, as a pair of doubles, and have all the operations defined for those (the question is what to do for transcendentals etc.), by recursing on real_* operations on both doubles.
next prev parent reply other threads:[~2020-08-11 16:19 UTC|newest] Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-05-31 12:51 [Bug target/95450] New: [10 " schwab@linux-m68k.org 2020-06-02 7:32 ` [Bug target/95450] [10/11 " rguenth at gcc dot gnu.org 2020-06-02 8:34 ` schwab@linux-m68k.org 2020-07-23 6:51 ` rguenth at gcc dot gnu.org 2020-08-11 16:14 ` carlos at redhat dot com 2020-08-11 16:17 ` mpolacek at gcc dot gnu.org 2020-08-11 16:19 ` jakub at gcc dot gnu.org [this message] 2020-08-11 16:46 ` jakub at gcc dot gnu.org 2020-08-11 16:54 ` jakub at gcc dot gnu.org 2020-08-11 17:26 ` jakub at gcc dot gnu.org 2020-08-25 5:18 ` cvs-commit at gcc dot gnu.org 2020-08-25 17:45 ` cvs-commit at gcc dot gnu.org 2020-08-25 18:25 ` jakub at gcc dot gnu.org
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