61 lines
2.1 KiB
C
61 lines
2.1 KiB
C
/*
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* Copyright (c) 2023, Red Hat, Inc. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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#include "jni.h"
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// See GCC bug 55522:
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//
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// "When used at link-time, [ GCC with -ffast-math ] may include
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// libraries or startup files that change the default FPU control word
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// or other similar optimizations."
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//
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// This breaks Java's floating point arithmetic.
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#if defined(__GNUC__)
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// On systems on which GCC bug 55522 has been fixed, this constructor
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// serves to reproduce that bug for the purposes of testing HotSpot.
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static void __attribute__((constructor)) set_flush_to_zero(void) {
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#if defined(__x86_64__)
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#define MXCSR_DAZ (1 << 6) /* Enable denormals are zero mode */
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#define MXCSR_FTZ (1 << 15) /* Enable flush to zero mode */
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unsigned int mxcsr = __builtin_ia32_stmxcsr ();
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mxcsr |= MXCSR_DAZ | MXCSR_FTZ;
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__builtin_ia32_ldmxcsr (mxcsr);
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#elif defined(__aarch64__)
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#define _FPU_FPCR_FZ (unsigned long)0x1000000
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#define _FPU_SETCW(fpcr) \
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__asm__ __volatile__ ("msr fpcr, %0" : : "r" (fpcr));
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/* Flush to zero, round to nearest, IEEE exceptions disabled. */
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_FPU_SETCW (_FPU_FPCR_FZ);
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#endif // CPU arch
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}
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#endif // defined(__GNUC__)
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