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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/102971] GCC cannot understand >>32 pattern Date: Wed, 27 Oct 2021 21:03:04 +0000 [thread overview] Message-ID: <bug-102971-4-aO5OUFg2ta@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-102971-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102971 --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- #include <cstdint> std::uint64_t umul_naive(std::uint64_t a,std::uint64_t b,std::uint64_t& high) noexcept { std::uint32_t a0(static_cast<std::uint32_t>(a)); std::uint32_t a1(static_cast<std::uint32_t>(a>>32)); std::uint32_t b0(static_cast<std::uint32_t>(b)); std::uint32_t b1(static_cast<std::uint32_t>(b>>32)); std::uint64_t c00(static_cast<std::uint64_t>(a0)*b0); std::uint64_t c01(static_cast<std::uint64_t>(a0)*b1); std::uint64_t c10(static_cast<std::uint64_t>(a1)*b0); std::uint64_t c11(static_cast<std::uint64_t>(a1)*b1); std::uint64_t d0{static_cast<std::uint32_t>(c00)}; std::uint64_t c00_high{c00>>32}; std::uint64_t c01_low{static_cast<std::uint32_t>(c01)}; std::uint64_t c01_high{c01>>32}; std::uint64_t c10_low{static_cast<std::uint32_t>(c10)}; std::uint64_t c10_high{c10>>32}; std::uint64_t d1{c00_high+c01_low+c10_low}; std::uint64_t d2{(d1>>32)+c10_high+c01_high}; std::uint64_t d3{(d2>>32)+c11}; high=d2|(d3<<32); return d0|(d1<<32); }
next prev parent reply other threads:[~2021-10-27 21:03 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-10-27 20:29 [Bug tree-optimization/102971] New: " unlvsur at live dot com 2021-10-27 20:30 ` [Bug tree-optimization/102971] " unlvsur at live dot com 2021-10-27 21:03 ` pinskia at gcc dot gnu.org [this message] 2021-10-28 8:19 ` [Bug target/102971] " rguenth at gcc dot gnu.org
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