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powerpc: Do not raise exception traps for fesetexcept/fesetexceptflag (BZ 30988)
According to ISO C23 (7.6.4.4), fesetexcept is supposed to set floating-point exception flags without raising a trap (unlike feraiseexcept, which is supposed to raise a trap if feenableexcept was called with the appropriate argument). This is a side-effect of how we implement the GNU extension feenableexcept, where feenableexcept/fesetenv/fesetmode/feupdateenv might issue prctl (PR_SET_FPEXC, PR_FP_EXC_PRECISE) depending of the argument. And on PR_FP_EXC_PRECISE, setting a floating-point exception flag triggers a trap. To make the both functions follow the C23, fesetexcept and fesetexceptflag now fail if the argument may trigger a trap. The math tests now check for an value different than 0, instead of bail out as unsupported for EXCEPTION_SET_FORCES_TRAP. Checked on powerpc64le-linux-gnu. Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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@ -39,16 +39,24 @@ do_test (void)
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return result;
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}
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if (EXCEPTION_SET_FORCES_TRAP)
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{
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puts ("setting exceptions traps, cannot test on this architecture");
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return 77;
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}
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/* Verify fesetexcept does not cause exception traps. */
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/* Verify fesetexcept does not cause exception traps. For architectures
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where setting the exception might result in traps the function should
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return a nonzero value. */
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ret = fesetexcept (FE_ALL_EXCEPT);
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_Static_assert (!(EXCEPTION_SET_FORCES_TRAP && !EXCEPTION_TESTS(float)),
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"EXCEPTION_SET_FORCES_TRAP only makes sense if the "
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"architecture suports exceptions");
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if (ret == 0)
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puts ("fesetexcept (FE_ALL_EXCEPT) succeeded");
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else
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{
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if (EXCEPTION_SET_FORCES_TRAP)
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{
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puts ("unexpected fesetexcept success");
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result = 1;
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}
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}
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else if (!EXCEPTION_SET_FORCES_TRAP)
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{
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puts ("fesetexcept (FE_ALL_EXCEPT) failed");
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if (EXCEPTION_TESTS (float))
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@ -63,14 +63,16 @@ do_test (void)
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result = 1;
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}
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if (EXCEPTION_SET_FORCES_TRAP)
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{
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puts ("setting exceptions traps, cannot test on this architecture");
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return 77;
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}
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/* The test is that this does not cause exception traps. */
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/* The test is that this does not cause exception traps. For architectures
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where setting the exception might result in traps the function should
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return a nonzero value. */
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ret = fesetexceptflag (&saved, FE_ALL_EXCEPT);
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if (ret != 0)
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_Static_assert (!(EXCEPTION_SET_FORCES_TRAP && !EXCEPTION_TESTS(float)),
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"EXCEPTION_SET_FORCES_TRAP only makes sense if the "
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"architecture suports exceptions");
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if (ret != 0 && !EXCEPTION_SET_FORCES_TRAP)
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{
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puts ("fesetexceptflag failed");
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result = 1;
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@ -31,6 +31,11 @@ fesetexcept (int excepts)
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& FE_INVALID_SOFTWARE));
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if (n.l != u.l)
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{
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if (n.l & fenv_exceptions_to_reg (excepts))
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/* Setting the exception flags may trigger a trap. ISO C 23 § 7.6.4.4
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does not allow it. */
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return -1;
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fesetenv_register (n.fenv);
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/* Deal with FE_INVALID_SOFTWARE not being implemented on some chips. */
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@ -44,7 +44,14 @@ __fesetexceptflag (const fexcept_t *flagp, int excepts)
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This may cause floating-point exceptions if the restored state
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requests it. */
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if (n.l != u.l)
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fesetenv_register (n.fenv);
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{
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if (n.l & fenv_exceptions_to_reg (excepts))
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/* Setting the exception flags may trigger a trap. ISO C 23 § 7.6.4.4
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does not allow it. */
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return -1;
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fesetenv_register (n.fenv);
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}
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/* Deal with FE_INVALID_SOFTWARE not being implemented on some chips. */
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if (flag & FE_INVALID)
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