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