| 1 | #include <assert.h>
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| 2 | #include <fenv.h>
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| 3 | #include <stdio.h>
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| 4 |
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| 5 | typedef struct
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| 6 | {
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| 7 | unsigned short __control_word;
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| 8 | unsigned short __reserved1;
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| 9 | unsigned short __status_word;
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| 10 | unsigned short __reserved2;
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| 11 | unsigned int more[5];
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| 12 | }
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| 13 | x86_387_fenv_t;
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| 14 |
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| 15 | int
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| 16 | feenableexcept (int exceptions)
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| 17 | {
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| 18 | exceptions &= 0x3f;
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| 19 |
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| 20 | /* Enable the traps in the 387 unit. */
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| 21 | unsigned short fctrl, orig_fctrl;
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| 22 | __asm__ __volatile__ ("fnstcw %0" : "=m" (*&orig_fctrl));
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| 23 | fctrl = orig_fctrl & ~exceptions;
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| 24 | if (fctrl != orig_fctrl)
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| 25 | __asm__ __volatile__ ("fldcw %0" : : "m" (*&fctrl));
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| 26 |
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| 27 | if (1)
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| 28 | {
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| 29 | /* Enable the traps in the SSE unit as well. */
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| 30 | unsigned int mxcsr, orig_mxcsr;
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| 31 | __asm__ __volatile__ ("stmxcsr %0" : "=m" (*&orig_mxcsr));
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| 32 | mxcsr = orig_mxcsr & ~(exceptions << 7);
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| 33 | if (mxcsr != orig_mxcsr)
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| 34 | __asm__ __volatile__ ("ldmxcsr %0" : : "m" (*&mxcsr));
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| 35 | }
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| 36 |
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| 37 | return 0x3f & ~orig_fctrl;
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| 38 | }
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| 39 |
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| 40 | static int
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| 41 | sigfpe_on_invalid ()
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| 42 | {
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| 43 | /* Clear FE_INVALID exceptions from past operations. */
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| 44 | feclearexcept (FE_INVALID);
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| 45 |
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| 46 | /* An FE_INVALID exception shall trigger a SIGFPE signal.
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| 47 | This call may fail on arm, arm64, riscv64 CPUs.
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| 48 | Also, possibly a bug in glibc/sysdeps/m68k/fpu/feenablxcpt.c: it sets
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| 49 | only bit 13, but should better set bits 15, 14, 13 of the control
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| 50 | register together. See
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| 51 | <https://sourceware.org/bugzilla/show_bug.cgi?id=30993>. */
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| 52 | int ret = feenableexcept (FE_INVALID);
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| 53 | if (ret == -1)
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| 54 | return -1;
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| 55 |
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| 56 | return 0;
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| 57 | }
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| 58 |
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| 59 | /* Test that feupdateenv(), unlike fesetenv(), can trigger traps. */
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| 60 |
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| 61 | int
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| 62 | main ()
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| 63 | {
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| 64 | fenv_t env1;
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| 65 |
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| 66 | /* Get to a known initial state. */
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| 67 | assert (feclearexcept (0x3f) == 0);
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| 68 |
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| 69 | /* Enable trapping on FE_INVALID. */
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| 70 | if (sigfpe_on_invalid () < 0)
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| 71 | {
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| 72 | fputs ("Skipping test: trapping floating-point exceptions are not supported on this machine.\n", stderr);
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| 73 | return 77;
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| 74 | }
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| 75 |
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| 76 | /* Save the current environment in env1. */
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| 77 | assert (fegetenv (&env1) == 0);
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| 78 |
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| 79 | /* Go back to the default environment. */
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| 80 | assert (fesetenv (FE_DFL_ENV) == 0);
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| 81 |
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| 82 | /* Modify the current environment. */
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| 83 | assert (feraiseexcept (FE_INVALID) == 0);
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| 84 |
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| 85 | /* Go back to env1.
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| 86 | Since the exceptions flag FE_INVALID is currently set, and since
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| 87 | env1 has trapping on FE_INVALID enabled, this should trap. */
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| 88 | assert (feupdateenv (&env1) == 0);
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| 89 |
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| 90 | return 0;
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| 91 | }
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