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Fix spurious "inexact" exceptions from __kernel_standard_l (bug 18245, bug 18583) [committed]
- From: Joseph Myers <joseph at codesourcery dot com>
- To: <libc-alpha at sourceware dot org>
- Date: Tue, 23 Jun 2015 17:27:18 +0000
- Subject: Fix spurious "inexact" exceptions from __kernel_standard_l (bug 18245, bug 18583) [committed]
- Authentication-results: sourceware.org; auth=none
__kernel_standard_l converts long double arguments to double for use
in SVID "struct exception". This has special-case handling for when
that conversion would overflow or underflow but the original long
double function wouldn't. However, it turns out that "inexact"
exceptions can be spurious here as well, when the function is exactly
determined and __kernel_standard_l is being called for a domain error.
This patch fixes this by using feholdexcept / fesetenv to avoid
exceptions from the conversion, replacing the previous special-case
logic for overflow and underflow (this covers all functions using
__kernel_standard_l, not just those that actually need a change, since
there doesn't seem to be much point in restricting things just to the
functions that mustn't get "inexact" here).
Tested for x86_64 and x86. Committed.
2015-06-23 Joseph Myers <joseph@codesourcery.com>
[BZ #18245]
[BZ #18583]
* sysdeps/ieee754/k_standardl.c: Include <fenv.h>.
(__kernel_standard_l): Use feholdexcept and fesetenv around
conversion to double instead of special-casing overflow and
underflow.
* math/libm-test.inc (fmod_test_data): Add more tests.
(remainder_test_data): Likewise.
(sqrt_test_data): Likewise.
diff --git a/math/libm-test.inc b/math/libm-test.inc
index 85a1746..03c3831 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -7115,12 +7115,16 @@ static const struct test_ff_f_data fmod_test_data[] =
/* fmod (+inf, y) == qNaN plus invalid exception. */
TEST_ff_f (fmod, plus_infty, 3, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
+ TEST_ff_f (fmod, plus_infty, -1.1L, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
/* fmod (-inf, y) == qNaN plus invalid exception. */
TEST_ff_f (fmod, minus_infty, 3, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
+ TEST_ff_f (fmod, minus_infty, -1.1L, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
/* fmod (x, +0) == qNaN plus invalid exception. */
TEST_ff_f (fmod, 3, 0, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
+ TEST_ff_f (fmod, -1.1L, 0, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
/* fmod (x, -0) == qNaN plus invalid exception. */
TEST_ff_f (fmod, 3, minus_zero, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
+ TEST_ff_f (fmod, -1.1L, minus_zero, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
/* fmod (x, +inf) == x for x not infinite. */
TEST_ff_f (fmod, 3.0, plus_infty, 3.0, NO_INEXACT_EXCEPTION),
@@ -8719,6 +8723,8 @@ static const struct test_ff_f_data remainder_test_data[] =
{
TEST_ff_f (remainder, 1, 0, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
TEST_ff_f (remainder, 1, minus_zero, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
+ TEST_ff_f (remainder, -1.1L, 0, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
+ TEST_ff_f (remainder, -1.1L, minus_zero, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
TEST_ff_f (remainder, plus_zero, plus_zero, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
TEST_ff_f (remainder, plus_zero, minus_zero, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
TEST_ff_f (remainder, minus_zero, plus_zero, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
@@ -8726,12 +8732,14 @@ static const struct test_ff_f_data remainder_test_data[] =
TEST_ff_f (remainder, plus_infty, minus_zero, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
TEST_ff_f (remainder, plus_infty, 0, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
TEST_ff_f (remainder, plus_infty, 1, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
+ TEST_ff_f (remainder, plus_infty, 1.1L, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
TEST_ff_f (remainder, plus_infty, 2, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
TEST_ff_f (remainder, plus_infty, plus_infty, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
TEST_ff_f (remainder, plus_infty, minus_infty, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
TEST_ff_f (remainder, minus_infty, minus_zero, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
TEST_ff_f (remainder, minus_infty, 0, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
TEST_ff_f (remainder, minus_infty, 1, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
+ TEST_ff_f (remainder, minus_infty, 1.1L, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
TEST_ff_f (remainder, minus_infty, 2, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
TEST_ff_f (remainder, minus_infty, plus_infty, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
TEST_ff_f (remainder, minus_infty, minus_infty, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
@@ -9507,6 +9515,7 @@ static const struct test_f_f_data sqrt_test_data[] =
/* sqrt (x) == qNaN plus invalid exception for x < 0. */
TEST_f_f (sqrt, -1, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
+ TEST_f_f (sqrt, -1.1L, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
TEST_f_f (sqrt, -max_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
TEST_f_f (sqrt, minus_infty, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
diff --git a/sysdeps/ieee754/k_standardl.c b/sysdeps/ieee754/k_standardl.c
index eaa2f66..aa95748 100644
--- a/sysdeps/ieee754/k_standardl.c
+++ b/sysdeps/ieee754/k_standardl.c
@@ -32,6 +32,7 @@
#include <math.h>
#include <math_private.h>
+#include <fenv.h>
#include <float.h>
#include <errno.h>
@@ -47,31 +48,14 @@ __kernel_standard_l (long double x, long double y, int type)
{
double dx, dy;
struct exception exc;
+ fenv_t env;
- if (isfinite (x))
- {
- long double ax = fabsl (x);
- if (ax > DBL_MAX)
- dx = __copysignl (DBL_MAX, x);
- else if (ax > 0 && ax < DBL_MIN)
- dx = __copysignl (DBL_MIN, x);
- else
- dx = x;
- }
- else
- dx = x;
- if (isfinite (y))
- {
- long double ay = fabsl (y);
- if (ay > DBL_MAX)
- dy = __copysignl (DBL_MAX, y);
- else if (ay > 0 && ay < DBL_MIN)
- dy = __copysignl (DBL_MIN, y);
- else
- dy = y;
- }
- else
- dy = y;
+ feholdexcept (&env);
+ dx = x;
+ dy = y;
+ math_force_eval (dx);
+ math_force_eval (dy);
+ fesetenv (&env);
switch (type)
{
--
Joseph S. Myers
joseph@codesourcery.com