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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug libstdc++/87744] Some valid instantiations of linear_congruential_engine produce compiler errors when __int128 isn't available Date: Tue, 06 Feb 2024 22:12:15 +0000 [thread overview] Message-ID: <bug-87744-4-jBav91tFLg@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-87744-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87744 Jakub Jelinek <jakub at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |jakub at gcc dot gnu.org --- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> --- As discussed on IRC, probably the if (!__builtin_mul_overflow(__l._M_lo, __x, &__lo)) optimization isn't a good idea, because most likely the compiler will in that case expand that to a full 64x64->128 multiplication plus testing that the upper 64 bits are or aren't zero, so computing everything this function needs and doing it again if there is overflow, without possibility to query what it computed.
next prev parent reply other threads:[~2024-02-06 22:12 UTC|newest] Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <bug-87744-4@http.gcc.gnu.org/bugzilla/> 2024-02-06 21:09 ` redi at gcc dot gnu.org 2024-02-06 21:21 ` redi at gcc dot gnu.org 2024-02-06 21:28 ` redi at gcc dot gnu.org 2024-02-06 21:32 ` jakub at gcc dot gnu.org 2024-02-06 21:46 ` redi at gcc dot gnu.org 2024-02-06 21:48 ` redi at gcc dot gnu.org 2024-02-06 21:51 ` redi at gcc dot gnu.org 2024-02-06 21:51 ` jakub at gcc dot gnu.org 2024-02-06 22:04 ` redi at gcc dot gnu.org 2024-02-06 22:12 ` jakub at gcc dot gnu.org [this message] 2024-02-06 22:14 ` jakub at gcc dot gnu.org 2024-02-07 10:14 ` lrflew.coll at gmail dot com 2024-02-07 10:38 ` redi at gcc dot gnu.org 2024-02-07 10:55 ` redi at gcc dot gnu.org 2024-02-15 11:44 ` cvs-commit at gcc dot gnu.org 2024-02-16 10:52 ` cvs-commit at gcc dot gnu.org 2024-02-16 19:12 ` cvs-commit at gcc dot gnu.org
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