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1 /*
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145
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2 * Copyright (C) 2005-2020 Free Software Foundation, Inc.
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111
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3 *
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4 * This file is free software; you can redistribute it and/or modify it
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5 * under the terms of the GNU General Public License as published by the
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6 * Free Software Foundation; either version 3, or (at your option) any
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7 * later version.
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8 *
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9 * This file is distributed in the hope that it will be useful, but
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10 * WITHOUT ANY WARRANTY; without even the implied warranty of
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11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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12 * General Public License for more details.
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13 *
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14 * Under Section 7 of GPL version 3, you are granted additional
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15 * permissions described in the GCC Runtime Library Exception, version
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16 * 3.1, as published by the Free Software Foundation.
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17 *
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18 * You should have received a copy of the GNU General Public License and
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19 * a copy of the GCC Runtime Library Exception along with this program;
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20 * see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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21 * <http://www.gnu.org/licenses/>.
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22 */
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23
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24 #ifndef _SOFT_FLOAT
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25 #define MXCSR_DAZ (1 << 6) /* Enable denormals are zero mode */
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26 #define MXCSR_FTZ (1 << 15) /* Enable flush to zero mode */
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27
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28 #ifndef __x86_64__
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29 /* All 64-bit targets have SSE and DAZ;
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30 only check them explicitly for 32-bit ones. */
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31 #include "cpuid.h"
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32
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33 __attribute__ ((target("fxsr,sse")))
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34 static void
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35 /* The i386 ABI only requires 4-byte stack alignment, so this is necessary
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36 to make sure the fxsave struct gets correct alignment.
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37 See PR27537 and PR28621. */
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38 __attribute__ ((force_align_arg_pointer))
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39 set_fast_math_sse (unsigned int edx)
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40 {
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41 unsigned int mxcsr;
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42
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43 if (edx & bit_FXSAVE)
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44 {
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45 /* Check if DAZ is available. */
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46 struct
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47 {
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48 unsigned short cwd;
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49 unsigned short swd;
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50 unsigned short twd;
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51 unsigned short fop;
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52 unsigned int fip;
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53 unsigned int fcs;
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54 unsigned int foo;
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55 unsigned int fos;
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56 unsigned int mxcsr;
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57 unsigned int mxcsr_mask;
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58 unsigned int st_space[32];
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59 unsigned int xmm_space[32];
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60 unsigned int padding[56];
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61 } __attribute__ ((aligned (16))) fxsave;
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62
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63 /* This is necessary since some implementations of FXSAVE
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64 do not modify reserved areas within the image. */
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65 fxsave.mxcsr_mask = 0;
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66
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67 __builtin_ia32_fxsave (&fxsave);
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68
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69 mxcsr = fxsave.mxcsr;
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70
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71 if (fxsave.mxcsr_mask & MXCSR_DAZ)
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72 mxcsr |= MXCSR_DAZ;
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73 }
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74 else
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75 mxcsr = __builtin_ia32_stmxcsr ();
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76
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77 mxcsr |= MXCSR_FTZ;
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78 __builtin_ia32_ldmxcsr (mxcsr);
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79 }
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80 #endif
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81
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82 static void __attribute__((constructor))
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83 set_fast_math (void)
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84 {
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85 #ifndef __x86_64__
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86 unsigned int eax, ebx, ecx, edx;
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87
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88 if (!__get_cpuid (1, &eax, &ebx, &ecx, &edx))
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89 return;
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90
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91 if (edx & bit_SSE)
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92 set_fast_math_sse (edx);
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93 #else
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94 unsigned int mxcsr = __builtin_ia32_stmxcsr ();
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95 mxcsr |= MXCSR_DAZ | MXCSR_FTZ;
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96 __builtin_ia32_ldmxcsr (mxcsr);
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97 #endif
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98 }
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99 #endif
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