[{"id":3680283,"web_url":"http://patchwork.ozlabs.org/comment/3680283/","msgid":"<13008704.CDJkKcVGEf@vir-laptop>","list_archive_url":null,"date":"2026-04-22T07:01:09","subject":"Re: [PATCH] libstdc++: simd: map 64-bit long double to double on sse\n [PR124657]","submitter":{"id":92625,"url":"http://patchwork.ozlabs.org/api/people/92625/","name":"Matthias Kretz","email":"MatthiasKretz@gmx.net"},"content":"Alexandre Oliva [Friday, 10 April 2026, 00:11:02 CEST]:\n> On Mar 26, 2026, Matthias Kretz wrote:\n> > For whatever reason, this is the first email I received of this thread.\n> \n> I guess I could have copied you.\n\nHere's the strange thing: Your mail reached me only via gcc-patches (which I'm \nsubscribed to with my m.kretz@gsi.de address). The libstdc++ mails and your CC \nto MatthiasKretz@gmx.net did not reach my inbox. And I can't find it in the \nJunk folder either.\n\nEmail hasn't been my friend in recent years. :(\n\n> \n> > I fear that this might lead to problems further down in the\n> > implementation. I think this should rather map '__intrinsic_type > double, N>' to '[[gnu::vector_size(16/32/64)]] double'. PPC has to do a\n> > similar thing (below).\n> \n> Indeed, I had filed PR124657 about the remaining compile failure with my\n> previous change, and your point above was exactly the solution for that\n> bit. But it got me to a subsequent problem that I'm addressing in a\n> later patch.\n> \n> \n> When long double is as wide as double on x86 (-mlong-double-64), make\n> the __intrinsic_type a vector of double.\n> \n> Regstrapped on x86_64-linux-gnu. This is not enough to enable\n> experimental/simd/pr109261_constexpr_simd.cc to compile with\n> -mlong-double-64. Ok to install?\n> \n> \n> for libstdc++-v3/ChangeLog\n> \n> \tPR libstdc++/124657\n> \t* include/experimental/bits/simd.h (__intrinsic_type::type):\n> \tMap long double to double.\n> ---\n> libstdc++-v3/include/experimental/bits/simd.h | 3 ++-\n> 1 file changed, 2 insertions(+), 1 deletion(-)\n> \n> diff --git a/libstdc++-v3/include/experimental/bits/simd.h\n> b/libstdc++-v3/include/experimental/bits/simd.h index\n> b96818af6e6ff..8c30c8af26881 100644\n> --- a/libstdc++-v3/include/experimental/bits/simd.h\n> +++ b/libstdc++-v3/include/experimental/bits/simd.h\n> @@ -2477,7 +2477,8 @@ template \n> static constexpr size_t _S_VBytes = _Bytes <= 16 ? 16 : _Bytes <= 32 ?\n> 32 : 64;\n> \n> using type [[__gnu__::__vector_size__(_S_VBytes)]]\n> - = conditional_t, long long int, _Tp>;\n> + = conditional_t, long long int,\n> +\t\t conditional_t, double, \n_Tp> >;\n> };\n> #endif // _GLIBCXX_SIMD_HAVE_SSE\n\nLooks good. But I would also prefer to make it cheaper for the standard 80-bit \nlong double case by guarding the extra conditional_t behind a\n\n#if __LDBL_MANT_DIG == __DBL_MANT_DIG","headers":{"Return-Path":"","X-Original-To":["incoming@patchwork.ozlabs.org","gcc-patches@gcc.gnu.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","gcc-patches@gcc.gnu.org"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n secure) header.d=gmx.net header.i=matthiaskretz@gmx.net header.a=rsa-sha256\n header.s=s31663417 header.b=iVtEIqB8;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org\n (client-ip=38.145.34.32; helo=vm01.sourceware.org;\n envelope-from=gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org;\n receiver=patchwork.ozlabs.org)","sourceware.org;\n\tdkim=pass (2048-bit key,\n secure) header.d=gmx.net header.i=matthiaskretz@gmx.net header.a=rsa-sha256\n header.s=s31663417 header.b=iVtEIqB8","sourceware.org;\n dmarc=pass (p=quarantine dis=none) header.from=gmx.net","sourceware.org; spf=pass smtp.mailfrom=gmx.net","server2.sourceware.org;\n arc=none smtp.remote-ip=212.227.17.22"],"Received":["from vm01.sourceware.org (vm01.sourceware.org [38.145.34.32])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519 server-signature ECDSA (secp384r1) server-digest SHA384)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4g0s023Cwfz1y2d\n\tfor ; Wed, 22 Apr 2026 17:52:50 +1000 (AEST)","from vm01.sourceware.org (localhost [127.0.0.1])\n\tby sourceware.org (Postfix) with ESMTP id 71B854BA901D\n\tfor ; Wed, 22 Apr 2026 07:52:48 +0000 (GMT)","from mout.gmx.net (mout.gmx.net [212.227.17.22])\n by sourceware.org (Postfix) with ESMTPS id 4F0534BA23D0;\n Wed, 22 Apr 2026 07:52:09 +0000 (GMT)","from client.hidden.invalid by mail.gmx.net (mrgmx105\n [212.227.17.168]) with ESMTPSA (Nemesis) id 1MRCOK-1w3GeR0nIq-00UgFC; Wed, 22\n Apr 2026 09:52:07 +0200"],"DKIM-Filter":["OpenDKIM Filter v2.11.0 sourceware.org 71B854BA901D","OpenDKIM Filter v2.11.0 sourceware.org 4F0534BA23D0"],"DMARC-Filter":"OpenDMARC Filter v1.4.2 sourceware.org 4F0534BA23D0","ARC-Filter":"OpenARC Filter v1.0.0 sourceware.org 4F0534BA23D0","ARC-Seal":"i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1776844329; cv=none;\n b=TywwIyE39asemI/9Rr7rQi/h0xvb7TISJYuWZH448Oz0vPWaDSgK+lYBj3KPrWZDOF2ui2p+qZ3OYptT87nW6vXyjDrC36oxW62g3FBDLf1d1ENcBdHNsdxEqev7hJcvKGPQu1mV1yb8ApvFBuowighoQssQg56d7WfB5Yxlcc8=","ARC-Message-Signature":"i=1; a=rsa-sha256; d=sourceware.org; s=key;\n t=1776844329; c=relaxed/simple;\n bh=vgv4yujcc1wGmIA1Zh3J/ce0V2awprQI/asSdDTi3u0=;\n h=DKIM-Signature:From:To:Subject:Date:Message-ID:MIME-Version;\n b=tfuON/80bhBBUrYdksATNIGRiwCvX2C1SHqllCfm8QorieNETW7gCpI4yU/Xdn/Hul6dT5cNuF3IQJMJroxty+SNg1gLVd1ZUVY3+b8bavajStCM3iV3RHaIyQhOvI33+pM8c96sQr43RGBP5skqj40N3j5rnInDWh9OF6xGgKU=","ARC-Authentication-Results":"i=1; server2.sourceware.org","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmx.net;\n s=s31663417; t=1776844327; x=1777449127; i=matthiaskretz@gmx.net;\n bh=RUKQSiE0M2cfLxw2GtMs6ckE5nhNC1kxwkVkMRYcdKc=;\n h=X-UI-Sender-Class:From:To:Cc:Subject:Date:Message-ID:In-Reply-To:\n References:MIME-Version:Content-Transfer-Encoding:Content-Type:cc:\n content-transfer-encoding:content-type:date:from:message-id:\n mime-version:reply-to:subject:to;\n b=iVtEIqB8yNQf6pPG8LzXtwQS4Bv7u+rlAjEgJds2PjCxymJovIWRId18zYy6tvLb\n MnMmYykl9jL+UbsY0jAyfGSmwKN1bBwIwNjxAmoxXhgQZeEfsADtGHAdy/J8/spSF\n KS97kQDi6+EQT5vUjbB8rkb4F+/fWjX2Jt4FrggDvUQW7850vjrbgK7tw7lBhdv5C\n +u/ChDyapOLxNqC1M+OerQfcCBKBzmn83YVCubK3LbCDk4ID23UHD6vRkUNqxCBBX\n 4UwxcfrUrh2RAqx9WHbA+m7ucmueOMbWj6YHOYHV7hChsxkT1A2Wny7JpgHZuvmh0\n t5C9WnsQi5+XTaAhrw==","X-UI-Sender-Class":"724b4f7f-cbec-4199-ad4e-598c01a50d3a","From":"Matthias Kretz ","To":"gcc-patches@gcc.gnu.org, Alexandre Oliva ","Cc":"libstdc++@gcc.gnu.org, Jonathan Wakely ","Subject":"Re: [PATCH] libstdc++: simd: map 64-bit long double to double on sse\n [PR124657]","Date":"Wed, 22 Apr 2026 09:01:09 +0200","Message-ID":"<13008704.CDJkKcVGEf@vir-laptop>","Organization":"GSI Helmholtz Center for Heavy Ion Research","In-Reply-To":"","References":"\n <47992676.fMDQidcC6G@vir-laptop>\n ","MIME-Version":"1.0","Content-Transfer-Encoding":"quoted-printable","Content-Type":"text/plain; charset=\"utf-8\"","X-Provags-ID":"V03:K1:+7Xy/vRIDieQQEaTLbV4ZB349S4xKTfiidlVEpLJQo0j0nhSBE9\n gu5OhRI/UKg162M2Y8UVHFoVwaPdHLeOv4qQVvpdlTG0Vjnr6MYunz3ydaRBbS3k8zDRW5+\n 7HZiwao7CufFxwzyNFPqHkGsKiw86MOMunTn6ctxekPoVG6X5DhU6/fsQExSH/Pfqm4Tslv\n UcyMQSRjKQBhL9JflxGHQ==","UI-OutboundReport":"notjunk:1;M01:P0:vapZSCKrYUk=;wyAB7OO/8R8XenBsPtkfSpsGshR\n JsNqEJZHaaL3C/S2PZHEDtCPKv5bPOEMpzQLP/KnMtv2rkhk9B/33PHsAyUwEC7jiqSu9iArD\n RJLklNlvNNBLAf66r6a6r/Rko2y0OfLv9QOuugx/faGDykmdvnN9ITy3BrwklSAiDiHnZg6bj\n KfpIhXFeinGybYXHGJbkBlCsWNI9uGtT8NV9isDJvRsGtwdpGRFoBO+MZxC3cF70ypimmoWqD\n aF9PpgMAc4iUYmPGyO9bErH5z1FiJoXixL8fklk4b9ID9Z+PxmWkZqEpYKcGxzwV0PNLnSfdB\n ol8E/IO9Y5hS+15P0px6wByWBl9yCendMOYUatbizSyJ9eqXZLg+gFigfuLkge/BoPagpFv1q\n CuGDQQ55+9JDYYYQmGEkYtoL/KymgoldRifTTBMAog3b1HJtAGONhjZVs0MZoEkwSNZeNmn8v\n L/07pu3c7Nb3HY9HCGL8gxO4r3BADGI6SoRN2AH9TM+Yls9V65v0civCILlIM80YjMdTLQTDZ\n Us290FSYYOcfc6Ml++/tfVWk07ojvReh+UqpTpu/6tWAICU80+TEVMvC1fDF0GGv5xXz0uczm\n rDBGVXRB3gqy1kAqngfP0zrzmzOpi4RVyB1N33jzt9yz4BardDCbiG18VG016RulGXrF38+FW\n PZEEiJXySvT5FWFzkYKqp1d4Sf5PhaAW5HqhVLbLFUG7va7/FV+0Tt9XmYfllxf5WNT4zKA+T\n Aw3IhCdYSY/CzDuN1FRWpyFZufXusIN+PM3oIAyqh1N4U4w6y17ggSDRtZRRistCcBoKrdw9a\n bfxEHHQA2/N7TN79ZXlPTnkd6zKAj6v4WMXFXRUzND2u46YZjjpwYX3VTHXNx3mNrqJFh3SLz\n iigF2DQKsorD+5QQ4YjXw/R5tVtT+s9/EHK3xDfClhRS175ya+dJtW7RNRli2O9t0qZI6+3yP\n g1bVCmesggxDo7PIaZwry85zbhOpsEzyG3X6xf2/RbzVmbqgsCVqTzp8UNovm1anqMRF0Cp41\n WqthQbJliQ02B1CamxpwKYE05vNu9kdGUGtIOmeY2Dnnsd2s7bttJkGtfvcosV9p6ysfekyTL\n lRUzhD4/npCgzrnp7UfZ66mMvjxE6SkVtfrXPiU/hBWKPrwWGu857o5ELtydIJ7V76eC4pQwZ\n hul4DYKusaXYhyrci13Spk+OHvw4JzyAN6EC/qkbf3QxozCQHWm0i5Y5VdMAOSJy92tTaUDdC\n vwAQgW/+8wwXKB73BXQlgYuB86zIzDYRM9OXQlRTMGAE4iwmqejwvAF9uhuQT3zt2HQDRw/P1\n nMIONQT1dthEtvBQ4d7ra0jQ+V+eYA4auF2H9cG58oqjfrSwP7SvW37uk0LVuCP/EG5ZltbpW\n +wqQqD5/CnpITgsw1+Ta6FHgULgTOWX4t9XWn48cizG4cA8Z5Y8vpbMR+YfK7+ZDgro8CE1nH\n wZZ05k/q7+XXt3sJbt4sSugKsmN1KRTurZBygne/FZ0sE9s4JZUFpHJAJ056iMPkcd1RW3OJL\n 0CIdYwk5GpUN5bAujErcf2a8ga++QFU3BiUiaZ6O2Ig35wj0XjG74MG/wxQ32Q4AoaIBwSoF1\n YrzatcZeUKavZfAyPlyD5G5NxE1MnSWlxwYUAZ0z0929YnwYgEI9e8hX4wq2jZyrYa+yXNKD0\n iG9klywVGeTatMdCCHPm74STm7dK+UOsXg7axN/q6b6FrdyziflgvAyXNp3tVUzgN7SAo2U0j\n kqvgTYAUFhUlxo6T7itUdfDWtS0H+HJmpIFJhauyZBlLUIFC8beMSOrgQNzshzTGzbWGKMUrp\n a1xPi5rOZGPyTYcj2BbYR0LvkAgD+6zg8eorAjMvbE8f2+MM0tHNMntEg2iCKsvyPKaQz0NhT\n U+1sXwlQvbX5NAtXrpnv7Ez6bg65C45oe4P5qUHhY3j3sifIPQIK9Y9E/b2HnaAqvOA+8Ctim\n cgN8kcn9oy031B2Zzf02C/3uw5asNhynYraS/9HjMeEiMyhT1D0aJGKeiamYcDYlK5R2s6+sB\n a4vvVwYE7fwhd2SrortifTtAYlmy8tyuPbT1BVZ6ZzATckSItgACr6SKztG7U0lWEof77Ejji\n URze3U2t5WPUtCwCMchepoCugWs9WkEAvxuTQvr26onnoy4xxP+6b5tTpXIe2XTsE2uzTDo9I\n 0lS5vS396ExNapIvjYfGnIs+x5mF0ccCyDJfPhM6x2ZXGUJSHrmWy4uVUqnAM9FF9Opi1tt2C\n HOlpf32+j96uhNaPJnB5W/ZuEbwI0MU/NJJVb3mE6rUj/iF2WvWThJwUszUnI9he9oTGEWrFW\n 7CxNjmzSBsyJNM7Q1uXCVSaZGe/OUv6dt5El6yS478uJ+VYFSik1Bc1d9koL1RSoWmng/36M4\n uanaLo60MDHh9ntULh2c4/vMDLQr+77cVyxVOXBxs16CAik1dfsgO2+PWxUTuxBaqD4rO3QQg\n mdus5VG5f+6mXzO+JUoabhHbVMLZOzP+EhcqLf1Tp7Y0v/bGad0z7991i4tIjp6+wqN4MNnta\n eZXRmKlWw10f1300Ojt6/59KvGLfAm3WfFGAs15ltSBuH2Zl6DAOS6Z8EyT1f/CpYnqv42pr8\n uMfxJVYwPwfSQp22YPXD2FS99hh8fZ9zTNSy2Fjs6R0nWb2VWUe1YdDijN54fynMecEI6iHiH\n oTPmvVQrcom7m4zgzb60mBTXKenXdu2ervT1/2Fs6Ml7AZH4Aq8Uy8FF2Xo510KKIk2MG9PqQ\n M9lvmByHSp/nKgvitW6aHH6InG94fDfhR8oY3UAWGtmCkzUeoV4UueUqh+DBhsLpiXdAW7kUn\n JR+PpUFL21NSKizoY+XcZLS2UBcSLQO61a1ZlmX0MTvFreA70xqyEOYfidaIhykkFp6agf57Z\n 6DD15YB0icnXz+yu27HGHMTW0eoQBib9yCa3rYmqsO8ADGW5fiUX389ykFrFppvrGX6XNec1n\n 7g6ru/JEpKVrtc1bOtksOgFlsEEpdKq6HXKgX8eF5fcvF2dfBn3q3ZaJKzbzPGNYu/YnT08dz\n qWfrbx+wMkQom/5HugdlfWqaAu6gKezrc/bo4KC/7y5Ju057FQcYCw0QdrkwUeEG5KNnCDUpN\n PTv33nRG8sQ+WTSA3L/AAzffKzPjmE5Yh1ZRm+wa4Zrm/6tRhcZiDPo24yG6IfOgsxyITvBft\n 5AduWPR+67hzu8ls2UXJH4WQysQiqjCZj6gnxusPZKHMVXHxld8MjsDoB3PAvrojbsgRgFbwr\n loTyLlWCDSCZNTtxI3cSjTlm1mx7oeMGi77E3WO8+uAlro8jGxvrgh/hWXuZgHdTqhr3Oz/EH\n gMtwhLo5SB06sSNyMjQqyIrRoWf5Ix7CoeyGX52/zu1s7eMvUAsy/MkY8mmFbP7jVig+m6E5b\n Md49jFbDeu6Jut96sjhsrcQ0wfK86Wp4tojqOIkt+irDNL1FUYN67FK5HCc3pdW+I0cQmh9+a\n gfIXhGMqUr4b1pMyjwUxJF01Zn/s7Z0Jj9AptDoMBcgOvFCmNqwH00Spo4yv09g5ftmzJ7e24\n 1RCp8tgdYj7cTypjUCOr+OiA9l3nPQtE7vqR7qi1z0+kDkh+q1eHI1q8TTKNa/PNx4iFJ0Bhb\n 98maXyHTXe5xYHr6H1QmbXYL/iRyHAgM8EHSVMr9KVhD45CTPS8w+HUnbNZM3X0XCXUq5x9zE\n fRGpmLrVQ/LplLjPRgLXeuQNATpjZjfqjho2ia921sAe0H4ljtfNDOesW7eSYGH5kpMVAWHS2\n Ce722grvjvb6EhXsH3jtKxbdXTb4L2LHADYsGaZBE/qX4XXSvMD1isaZ3aY/wl/oTLpSr2AFo\n 3cGodEIgeC4o7G5ALjuWxu88K81mYU6eu1ocJU9wXzTLRY5fSJG/PzJOo2yBLnFUsKlv3vjsZ\n sb11sRsOq/1u/mmLUTVxtirk9upDeK2nE29fa5a7TwtbWZRzsf1rPnzvxip/XcT92wkd0D6aC\n I62OJP9XxzvfqdnmVXe/5MBGnQMCUM2b6PFRQ1tPjP1/fjaPi/RICovS1AB6i4S4Tg1cSJwJb\n 7r/h2+codQT6kPucKgFm2R74GJcfShHLZliHgDOIeIEx7QR2b3MBTtsJWx9MegucXb8fbp4/8\n G1XA1emwuqRTCvO8O4a09kif0gKmLL79J2vjNcobxvSFM9WiauCrlq7Tf7YA0u5UiT6/DSx2p\n OgNdGphNryeKyF9Dm2heTR/glAiPcbAfpASsg0tKiWS3GbSzTmfjusrFAjDlhSDjQ5L2GGLH0\n A8LfbzBfyoCDSy5bNbN7N0yRg1q46oZWOjEQFMk31SNASx2IXIawIvI2Hy6pltgLc2aipFUAi\n YYKOe8Q9s5fiAPVzSEoFueJlG//7ahihTB5UMQJdRLTAuzT90yyClEd6dvkWiXGiv9o8cLE2h\n PZ3+IkrNhfkm8DpcU9mCCVw/Cg7EBR6uiRhdmXUECN9tu4dP1VeczXcpItw7oCIPNmHbO4snx\n 3NrA5USYM6KAKWH7SG4sEK1dNBa5wRopESsAddhvQVQRGjvihQD/BHgxYiEpH6vDECe47o8KV\n 0xoCVXVgG0H3irrJjNUrkZ2b/AQr60iBHdqiMYKMthK7vLEx7nS2uFxdbzxsA0UD21NNHF6hA\n 7+bQZL9xOv39JVVjbi7ZiU9vbZ6PG8D/AL/+hMvRD+V6w7ILA0EvxZQ7o9pl6rOA50un/6Sbx\n +8OCoYQl5napsNqZgDompHsjaxbw9hyQJM/IBrgQTIlFPA60/PfEXnRBsaJJfBS0npuTXO3d9\n LAjXdHqRn46JRDdWaevko6rGMIAbIxG2A7VwZL2nbZ7m5WaeBa4y1VoCRRw6r+cugg8CoSGEF\n X+7KZUCyMgSk35cP7oxEugZXwQvh9e65QWa+QPMvBsdFT3QrV2BFvyPJwsLcylxT00XjAYpYn\n hK1LzLm4oo2y35krUqq7ZpJwKoOKvpmDxtT8fTo9uOkX9GjEIPHP73TgVe0XZqBZq8j9CBoW/\n mX+wzI0XWjAIzW9+J02lCfEvvRJY1csIbq70+hcDvJuL5XG8YZGOenA9t6+1iEf7+d30X/PbN\n Cs1GlGi8GWlHllKb+mrVGmQeI971T2b/SLWzA8FgmKiFQfiPESoQRlYlcpaiwu7UszcMME4xz\n DUwRGeVVXOwNsatrNGr92/rFyZdxPemwdklRTT1IGrcU4HCMGbFrOqIsmvk8CO604+pTUvF7R\n VeiAu3XWCiMCp2/334UCpo+ygbPzsf31SYj3hOoS5sh0kckWLrvltShSpShuWOTXBeK4Dnlvm\n YLdhDCEYiSUq8e7lTsCKOt9nUb980NmDLek47Yr6cReCR4ys145mlsneDS25GHYM9RgqpouOZ\n JEehTvGOX5bKvPCyY4KpQy+w9giDTbDW4rU8VEK1paC64m06mS2YXsNI2xZtohODvw6F3h6wN\n mwT2gYWtitjT7t9/MSb6WX7QnYCn7wTBwAYKAfTXxetP6lENh6BaMF8RBmv7CFLRYWI2EzWFl\n Nu30DGWHsnFkZromfrosxZxQAOSUcPXRfGQGXLYjHNNx+FcT/7bkkkSkR","X-BeenThere":"gcc-patches@gcc.gnu.org","X-Mailman-Version":"2.1.30","Precedence":"list","List-Id":"Gcc-patches mailing list ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org"}}]