| 1 | /* Set floating-point environment exception handling. |
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| 2 | Copyright (C) 1997-2024 Free Software Foundation, Inc. |
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| 3 | This file is part of the GNU C Library. |
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| 4 | |
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| 5 | The GNU C Library is free software; you can redistribute it and/or |
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| 6 | modify it under the terms of the GNU Lesser General Public |
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| 7 | License as published by the Free Software Foundation; either |
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| 8 | version 2.1 of the License, or (at your option) any later version. |
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| 9 | |
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| 10 | The GNU C Library is distributed in the hope that it will be useful, |
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| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 13 | Lesser General Public License for more details. |
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| 14 | |
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| 15 | You should have received a copy of the GNU Lesser General Public |
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| 16 | License along with the GNU C Library; if not, see |
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| 17 | <https://www.gnu.org/licenses/>. */ |
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| 18 | |
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| 19 | #include <fenv.h> |
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| 20 | #include <ldsodefs.h> |
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| 21 | |
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| 22 | int |
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| 23 | __fesetexceptflag (const fexcept_t *flagp, int excepts) |
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| 24 | { |
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| 25 | /* The flags can be set in the 387 unit or in the SSE unit. When we need to |
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| 26 | clear a flag, we need to do so in both units, due to the way fetestexcept |
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| 27 | is implemented. |
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| 28 | When we need to set a flag, it is sufficient to do it in the SSE unit, |
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| 29 | because that is guaranteed to not trap. However, on i386 CPUs that have |
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| 30 | only a 387 unit, set the flags in the 387, as long as this cannot trap. */ |
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| 31 | |
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| 32 | fenv_t temp; |
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| 33 | |
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| 34 | excepts &= FE_ALL_EXCEPT; |
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| 35 | |
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| 36 | /* Get the current x87 FPU environment. We have to do this since we |
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| 37 | cannot separately set the status word. |
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| 38 | Note: fnstenv masks all floating-point exceptions until the fldenv |
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| 39 | or fldcw below. */ |
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| 40 | __asm__ ("fnstenv %0" : "=m" (*&temp)); |
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| 41 | |
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| 42 | if (CPU_FEATURE_USABLE (SSE)) |
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| 43 | { |
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| 44 | unsigned int mxcsr; |
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| 45 | |
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| 46 | /* Clear relevant flags. */ |
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| 47 | temp.__status_word &= ~(excepts & ~ *flagp); |
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| 48 | |
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| 49 | /* Store the new status word (along with the rest of the environment). */ |
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| 50 | __asm__ ("fldenv %0" : : "m" (*&temp)); |
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| 51 | |
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| 52 | /* And now similarly for SSE. */ |
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| 53 | __asm__ ("stmxcsr %0" : "=m" (*&mxcsr)); |
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| 54 | |
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| 55 | /* Clear or set relevant flags. */ |
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| 56 | mxcsr ^= (mxcsr ^ *flagp) & excepts; |
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| 57 | |
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| 58 | /* Put the new data in effect. */ |
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| 59 | __asm__ ("ldmxcsr %0" : : "m" (*&mxcsr)); |
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| 60 | } |
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| 61 | else |
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| 62 | { |
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| 63 | /* Clear or set relevant flags. */ |
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| 64 | temp.__status_word ^= (temp.__status_word ^ *flagp) & excepts; |
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| 65 | |
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| 66 | if ((~temp.__control_word) & temp.__status_word & excepts) |
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| 67 | { |
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| 68 | /* Setting the exception flags may trigger a trap (at the next |
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| 69 | floating-point instruction, but that does not matter). |
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| 70 | ISO C 23 ยง 7.6.4.5 does not allow it. */ |
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| 71 | __asm__ volatile ("fldcw %0" : : "m" (*&temp.__control_word)); |
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| 72 | return -1; |
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| 73 | } |
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| 74 | |
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| 75 | /* Store the new status word (along with the rest of the environment). */ |
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| 76 | __asm__ ("fldenv %0" : : "m" (*&temp)); |
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| 77 | } |
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| 78 | |
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| 79 | /* Success. */ |
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| 80 | return 0; |
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| 81 | } |
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| 82 | |
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| 83 | #include <shlib-compat.h> |
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| 84 | #if SHLIB_COMPAT (libm, GLIBC_2_1, GLIBC_2_2) |
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| 85 | strong_alias (__fesetexceptflag, __old_fesetexceptflag) |
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| 86 | compat_symbol (libm, __old_fesetexceptflag, fesetexceptflag, GLIBC_2_1); |
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| 87 | #endif |
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| 88 | |
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| 89 | versioned_symbol (libm, __fesetexceptflag, fesetexceptflag, GLIBC_2_2); |
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| 90 | |
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