{"id":2175299,"url":"http://patchwork.ozlabs.org/api/1.0/patches/2175299/?format=json","project":{"id":41,"url":"http://patchwork.ozlabs.org/api/1.0/projects/41/?format=json","name":"GNU C Library","link_name":"glibc","list_id":"libc-alpha.sourceware.org","list_email":"libc-alpha@sourceware.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20251217175554.1157780-9-adhemerval.zanella@linaro.org>","date":"2025-12-17T17:51:54","name":"[8/8] math: Use math_opt_barrier on underflow/overflow","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"fb55a51d5de9b555559f6406ad6c3b6793337a18","submitter":{"id":66065,"url":"http://patchwork.ozlabs.org/api/1.0/people/66065/?format=json","name":"Adhemerval Zanella Netto","email":"adhemerval.zanella@linaro.org"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/glibc/patch/20251217175554.1157780-9-adhemerval.zanella@linaro.org/mbox/","series":[{"id":485739,"url":"http://patchwork.ozlabs.org/api/1.0/series/485739/?format=json","date":"2025-12-17T17:51:48","name":"Improve test when building with clang","version":1,"mbox":"http://patchwork.ozlabs.org/series/485739/mbox/"}],"check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2175299/checks/","tags":{},"headers":{"Return-Path":"","X-Original-To":["incoming@patchwork.ozlabs.org","libc-alpha@sourceware.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","libc-alpha@sourceware.org"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=linaro.org header.i=@linaro.org header.a=rsa-sha256\n header.s=google header.b=Rm0aab5m;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=sourceware.org\n (client-ip=38.145.34.32; helo=vm01.sourceware.org;\n envelope-from=libc-alpha-bounces~incoming=patchwork.ozlabs.org@sourceware.org;\n receiver=patchwork.ozlabs.org)","sourceware.org;\n\tdkim=pass (2048-bit key,\n unprotected) header.d=linaro.org header.i=@linaro.org header.a=rsa-sha256\n header.s=google header.b=Rm0aab5m","sourceware.org;\n dmarc=pass (p=none dis=none) header.from=linaro.org","sourceware.org; spf=pass smtp.mailfrom=linaro.org","server2.sourceware.org;\n arc=none smtp.remote-ip=209.85.210.169"],"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 4dWhMM5BWvz1y0P\n\tfor ; Thu, 18 Dec 2025 04:57:03 +1100 (AEDT)","from vm01.sourceware.org (localhost [127.0.0.1])\n\tby sourceware.org (Postfix) with ESMTP id 7C2374BA2E2E\n\tfor ; Wed, 17 Dec 2025 17:57:01 +0000 (GMT)","from mail-pf1-f169.google.com (mail-pf1-f169.google.com\n [209.85.210.169])\n by sourceware.org (Postfix) with ESMTPS id A03574BA2E07\n for ; Wed, 17 Dec 2025 17:56:16 +0000 (GMT)","by mail-pf1-f169.google.com with SMTP id\n d2e1a72fcca58-7bab7c997eeso6792886b3a.0\n for ; Wed, 17 Dec 2025 09:56:16 -0800 (PST)","from ubuntu-vm.. 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J . Lu\" , Collin Funk ,\n Sam James ","Subject":"[PATCH 8/8] math: Use math_opt_barrier on underflow/overflow","Date":"Wed, 17 Dec 2025 14:51:54 -0300","Message-ID":"<20251217175554.1157780-9-adhemerval.zanella@linaro.org>","X-Mailer":"git-send-email 2.43.0","In-Reply-To":"<20251217175554.1157780-1-adhemerval.zanella@linaro.org>","References":"<20251217175554.1157780-1-adhemerval.zanella@linaro.org>","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit","X-BeenThere":"libc-alpha@sourceware.org","X-Mailman-Version":"2.1.30","Precedence":"list","List-Id":"Libc-alpha mailing list ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"libc-alpha-bounces~incoming=patchwork.ozlabs.org@sourceware.org"},"content":"This avoids compiler to move the operation before the 'iy' compare.\n\nIt fixes math/test-float128-pow regreesions when building with clang:\n\nFailure: pow (-0x1.000002p+0, 0xf.ffffffffffff8p+1020): Exception \"Underflow\" set\nFailure: pow (-0x1.000002p+0, 0xf.ffffffffffffbffffffffffffcp+1020): Exception \"Underflow\" set\nFailure: pow (-0x1.000002p+0, 0xf.fffffffffffffffffffffffffff8p+16380): Exception \"Underflow\" set\nFailure: pow (-0x1.000002p+0, 0xf.fffffffffffffffp+16380): Exception \"Underflow\" set\nFailure: pow (-0x1.000002p+0, 0xf.fffffp+124): Exception \"Underflow\" set\nFailure: pow (-0x1.00000ep+0, 0xf.ffffffffffff8p+1020): Exception \"Underflow\" set\nFailure: pow (-0x1.00000ep+0, 0xf.ffffffffffffbffffffffffffcp+1020): Exception \"Underflow\" set\nFailure: pow (-0x1.00000ep+0, 0xf.fffffffffffffffffffffffffff8p+16380): Exception \"Underflow\" set\nFailure: pow (-0x1.00000ep+0, 0xf.fffffffffffffffp+16380): Exception \"Underflow\" set\nFailure: pow (-0x2p+0, -0xf.ffffffffffff8p+1020): Exception \"Overflow\" set\nFailure: pow (-0x2p+0, -0xf.ffffffffffffbffffffffffffcp+1020): Exception \"Overflow\" set\nFailure: pow (-0x2p+0, -0xf.fffffffffffffffffffffffffff8p+16380): Exception \"Overflow\" set\nFailure: pow (-0x2p+0, -0xf.fffffffffffffffp+16380): Exception \"Overflow\" set\nFailure: pow (-0x2p+0, -0xf.fffffp+124): Exception \"Overflow\" set\nFailure: pow (-0x2p+0, 0xf.ffffffffffff8p+1020): Exception \"Underflow\" set\nFailure: pow (-0x2p+0, 0xf.ffffffffffffbffffffffffffcp+1020): Exception \"Underflow\" set\nFailure: pow (-0x2p+0, 0xf.fffffffffffffffffffffffffff8p+16380): Exception \"Underflow\" set\nFailure: pow (-0x2p+0, 0xf.fffffffffffffffp+16380): Exception \"Underflow\" set\nFailure: pow (-0x2p+0, 0xf.fffffp+124): Exception \"Underflow\" set\n[...]\n\nChecked on x86_64-linux-gnu and aarch64-linux-gnu with gcc-15 and\nclang-18.\n---\n sysdeps/ieee754/ldbl-128/e_powl.c | 6 ++++--\n 1 file changed, 4 insertions(+), 2 deletions(-)","diff":"diff --git a/sysdeps/ieee754/ldbl-128/e_powl.c b/sysdeps/ieee754/ldbl-128/e_powl.c\nindex 4e20616705..9ff5a43573 100644\n--- a/sysdeps/ieee754/ldbl-128/e_powl.c\n+++ b/sysdeps/ieee754/ldbl-128/e_powl.c\n@@ -279,9 +279,11 @@ __ieee754_powl (_Float128 x, _Float128 y)\n if (iy > 0x407d654b)\n \t{\n \t if (ix <= 0x3ffeffff)\n-\t return (hy < 0) ? huge * huge : tiny * tiny;\n+\t return (hy < 0) ? math_opt_barrier (huge * huge)\n+\t : math_opt_barrier (tiny * tiny);\n \t if (ix >= 0x3fff0000)\n-\t return (hy > 0) ? huge * huge : tiny * tiny;\n+\t return (hy > 0) ? math_opt_barrier (huge * huge)\n+\t : math_opt_barrier (tiny * tiny);\n \t}\n /* over/underflow if x is not close to one */\n if (ix < 0x3ffeffff)\n","prefixes":["8/8"]}