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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/94083] inefficient soft-float x!=Inf code Date: Wed, 28 Feb 2024 09:51:44 +0000 [thread overview] Message-ID: <bug-94083-4-g2ethqnBNp@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-94083-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94083 Jakub Jelinek <jakub at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |jakub at gcc dot gnu.org, | |jsm28 at gcc dot gnu.org --- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Shall __builtin_isinf (x) or __builtin_isinf_sign (x) raise exception if x is a sNaN? Or never? Or it can but doesn't have to? glibc's int64_t hx,lx; GET_LDOUBLE_WORDS64(hx,lx,x); lx |= (hx & 0x7fffffffffffffffLL) ^ 0x7fff000000000000LL; lx |= -lx; return ~(lx >> 63) & (hx >> 62); doesn't, but I think when we lower __builtin_isinf to fabs (x) (which should just clear the sign bit, not raise exception) u<= <max_representable_finite>, it would. If we wouldn't need to raise exception, I think fastest would be to pattern recognize the fabs (x) <= <max_representable> and emit there the (lx | ((hx & 0x7fffffffffffffffLL) ^ 0x7fff000000000000LL)) != 0. But __builtin_islessequal (__builtin_fabsf128 (x), __builtin_nextafterf128 (__builtin_inff128 (), 0.0f128)) I think should raise exception and those 2 will be indistinguishable, so maybe just recognize that case during expansion if 2 libcalls would be needed and emit the equality comparison instead. Or do both depending on if -fsignaling-nans is specified or not?
next prev parent reply other threads:[~2024-02-28 9:51 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <bug-94083-4@http.gcc.gnu.org/bugzilla/> 2020-11-07 21:22 ` wilson at gcc dot gnu.org 2021-08-16 21:40 ` pinskia at gcc dot gnu.org 2024-02-27 19:48 ` pinskia at gcc dot gnu.org 2024-02-27 19:49 ` pinskia at gcc dot gnu.org 2024-02-28 9:51 ` jakub at gcc dot gnu.org [this message] 2024-02-28 10:24 ` harald at gigawatt dot nl 2024-02-28 10:33 ` jakub at gcc dot gnu.org 2024-02-28 11:42 ` jsm28 at gcc dot gnu.org 2024-02-28 22:19 ` harald at gigawatt dot nl
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