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Fix fdim handling of infinities (bug 15797)
- From: "Joseph S. Myers" <joseph at codesourcery dot com>
- To: <libc-alpha at sourceware dot org>
- Date: Wed, 21 Aug 2013 16:43:59 +0000
- Subject: Fix fdim handling of infinities (bug 15797)
This patch fixes bug 15797, incorrect fdim handling of infinities, by
removing the bogus check for infinities when returning x - y for NaN
arguments and instead checking later when determining whether an
infinite result means overflow. Appropriate testcases are added and
existing ones made to verify that errno is unchanged. (It does not do
anything about bug 6796, missing errno setting on overflow from
architecture-specific versions, or add any testcases relating to
overflow.)
Tested x86_64 and x86.
2013-08-21 Joseph Myers <joseph@codesourcery.com>
[BZ #15797]
* math/s_fdim.c (__fdim): Check for infinite arguments if result
is infinite, not alongside NaN test.
* math/s_fdimf.c (__fdimf): Likewise.
* math/s_fdiml.c (__fdiml): Likewise.
* math/libm-test.inc (fdim_test_data): Add more tests. Test that
errno is unchanged.
diff --git a/math/libm-test.inc b/math/libm-test.inc
index 25ea336..43c4a8f 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -8144,33 +8144,37 @@ fabs_test (void)
static const struct test_ff_f_data fdim_test_data[] =
{
- TEST_ff_f (fdim, 0, 0, 0, NO_INEXACT_EXCEPTION),
- TEST_ff_f (fdim, 9, 0, 9, NO_INEXACT_EXCEPTION),
- TEST_ff_f (fdim, 0, 9, 0, NO_INEXACT_EXCEPTION),
- TEST_ff_f (fdim, -9, 0, 0, NO_INEXACT_EXCEPTION),
- TEST_ff_f (fdim, 0, -9, 9, NO_INEXACT_EXCEPTION),
-
- TEST_ff_f (fdim, plus_infty, 9, plus_infty, NO_INEXACT_EXCEPTION),
- TEST_ff_f (fdim, plus_infty, -9, plus_infty, NO_INEXACT_EXCEPTION),
- TEST_ff_f (fdim, minus_infty, 9, 0, NO_INEXACT_EXCEPTION),
- TEST_ff_f (fdim, minus_infty, -9, 0, NO_INEXACT_EXCEPTION),
- TEST_ff_f (fdim, 9, minus_infty, plus_infty, NO_INEXACT_EXCEPTION),
- TEST_ff_f (fdim, -9, minus_infty, plus_infty, NO_INEXACT_EXCEPTION),
- TEST_ff_f (fdim, 9, plus_infty, 0, NO_INEXACT_EXCEPTION),
- TEST_ff_f (fdim, -9, plus_infty, 0, NO_INEXACT_EXCEPTION),
-
- TEST_ff_f (fdim, 0, qnan_value, qnan_value, NO_INEXACT_EXCEPTION),
- TEST_ff_f (fdim, 9, qnan_value, qnan_value, NO_INEXACT_EXCEPTION),
- TEST_ff_f (fdim, -9, qnan_value, qnan_value, NO_INEXACT_EXCEPTION),
- TEST_ff_f (fdim, qnan_value, 9, qnan_value, NO_INEXACT_EXCEPTION),
- TEST_ff_f (fdim, qnan_value, -9, qnan_value, NO_INEXACT_EXCEPTION),
- TEST_ff_f (fdim, plus_infty, qnan_value, qnan_value, NO_INEXACT_EXCEPTION),
- TEST_ff_f (fdim, minus_infty, qnan_value, qnan_value, NO_INEXACT_EXCEPTION),
- TEST_ff_f (fdim, qnan_value, plus_infty, qnan_value, NO_INEXACT_EXCEPTION),
- TEST_ff_f (fdim, qnan_value, minus_infty, qnan_value, NO_INEXACT_EXCEPTION),
- TEST_ff_f (fdim, qnan_value, qnan_value, qnan_value, NO_INEXACT_EXCEPTION),
-
- TEST_ff_f (fdim, plus_infty, plus_infty, 0, NO_INEXACT_EXCEPTION),
+ TEST_ff_f (fdim, 0, 0, 0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, 9, 0, 9, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, 0, 9, 0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, -9, 0, 0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, 0, -9, 9, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+
+ TEST_ff_f (fdim, plus_infty, 9, plus_infty, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, plus_infty, -9, plus_infty, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, minus_infty, 9, 0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, minus_infty, -9, 0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, 9, minus_infty, plus_infty, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, -9, minus_infty, plus_infty, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, 9, plus_infty, 0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, -9, plus_infty, 0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+
+ TEST_ff_f (fdim, 0, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, 9, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, -9, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, qnan_value, 0, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, qnan_value, 9, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, qnan_value, -9, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, plus_infty, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, minus_infty, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, qnan_value, plus_infty, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, qnan_value, minus_infty, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, qnan_value, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+
+ TEST_ff_f (fdim, plus_infty, plus_infty, 0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, plus_infty, minus_infty, plus_infty, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, minus_infty, plus_infty, 0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_ff_f (fdim, minus_infty, minus_infty, 0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
};
static void
diff --git a/math/s_fdim.c b/math/s_fdim.c
index 2f97948..f8fd804 100644
--- a/math/s_fdim.c
+++ b/math/s_fdim.c
@@ -26,16 +26,16 @@ __fdim (double x, double y)
int clsx = fpclassify (x);
int clsy = fpclassify (y);
- if (clsx == FP_NAN || clsy == FP_NAN
- || (y < 0 && clsx == FP_INFINITE && clsy == FP_INFINITE))
- /* Raise invalid flag. */
+ if (clsx == FP_NAN || clsy == FP_NAN)
+ /* Raise invalid flag for signaling but not quiet NaN. */
return x - y;
if (x <= y)
return 0.0;
double r = x - y;
- if (fpclassify (r) == FP_INFINITE)
+ if (fpclassify (r) == FP_INFINITE
+ && clsx != FP_INFINITE && clsy != FP_INFINITE)
__set_errno (ERANGE);
return r;
diff --git a/math/s_fdimf.c b/math/s_fdimf.c
index 03810b5..86efe6e 100644
--- a/math/s_fdimf.c
+++ b/math/s_fdimf.c
@@ -26,16 +26,16 @@ __fdimf (float x, float y)
int clsx = fpclassify (x);
int clsy = fpclassify (y);
- if (clsx == FP_NAN || clsy == FP_NAN
- || (y < 0 && clsx == FP_INFINITE && clsy == FP_INFINITE))
- /* Raise invalid flag. */
+ if (clsx == FP_NAN || clsy == FP_NAN)
+ /* Raise invalid flag for signaling but not quiet NaN. */
return x - y;
if (x <= y)
return 0.0f;
float r = x - y;
- if (fpclassify (r) == FP_INFINITE)
+ if (fpclassify (r) == FP_INFINITE
+ && clsx != FP_INFINITE && clsy != FP_INFINITE)
__set_errno (ERANGE);
return r;
diff --git a/math/s_fdiml.c b/math/s_fdiml.c
index 5604532..030fcc2 100644
--- a/math/s_fdiml.c
+++ b/math/s_fdiml.c
@@ -26,16 +26,16 @@ __fdiml (long double x, long double y)
int clsx = fpclassify (x);
int clsy = fpclassify (y);
- if (clsx == FP_NAN || clsy == FP_NAN
- || (y < 0 && clsx == FP_INFINITE && clsy == FP_INFINITE))
- /* Raise invalid flag. */
+ if (clsx == FP_NAN || clsy == FP_NAN)
+ /* Raise invalid flag for signaling but not quiet NaN. */
return x - y;
if (x <= y)
return 0.0f;
long double r = x - y;
- if (fpclassify (r) == FP_INFINITE)
+ if (fpclassify (r) == FP_INFINITE
+ && clsx != FP_INFINITE && clsy != FP_INFINITE)
__set_errno (ERANGE);
return r;
--
Joseph S. Myers
joseph@codesourcery.com