From 47a9eeb9ba72fd30766bdf4faa7d46b8ca33a7fd Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Tue, 24 Oct 2023 08:37:15 -0300 Subject: i686: Do not raise exception traps on fesetexcept (BZ 30989) 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). The flags can be set in the 387 unit or in the SSE unit. To set a flag, it is sufficient to do it in the SSE unit, because that is guaranteed to not trap. However, on i386 CPUs that have only a 387 unit, set the flags in the 387, as long as this cannot trap. Checked on i686-linux-gnu. Reviewed-by: Carlos O'Donell --- math/test-fesetexcept-traps.c | 26 +++++++++++++++++++++++--- 1 file changed, 23 insertions(+), 3 deletions(-) (limited to 'math') diff --git a/math/test-fesetexcept-traps.c b/math/test-fesetexcept-traps.c index 7efcd0343a..9e2023962b 100644 --- a/math/test-fesetexcept-traps.c +++ b/math/test-fesetexcept-traps.c @@ -19,6 +19,7 @@ #include #include #include +#include static int do_test (void) @@ -41,12 +42,32 @@ do_test (void) /* Verify fesetexcept does not cause exception traps. For architectures where setting the exception might result in traps the function should - return a nonzero value. */ + return a nonzero value. + Also check if the function does not alter the exception mask. */ ret = fesetexcept (FE_ALL_EXCEPT); _Static_assert (!(EXCEPTION_SET_FORCES_TRAP && !EXCEPTION_TESTS(float)), "EXCEPTION_SET_FORCES_TRAP only makes sense if the " "architecture suports exceptions"); + { + int exc_before = fegetexcept (); + ret = fesetexcept (FE_ALL_EXCEPT); + int exc_after = fegetexcept (); + if (exc_before != exc_after) + { + puts ("fesetexcept (FE_ALL_EXCEPT) changed the exceptions mask"); + return 1; + } + } + + /* Execute some floating-point operations, since on some CPUs exceptions + triggers a trap only at the next floating-point instruction. */ + volatile double a = 1.0; + volatile double b = a + a; + math_force_eval (b); + volatile long double al = 1.0L; + volatile long double bl = al + al; + math_force_eval (bl); if (ret == 0) { @@ -72,5 +93,4 @@ do_test (void) return result; } -#define TEST_FUNCTION do_test () -#include "../test-skeleton.c" +#include -- cgit 1.4.1