File ldbl-128ibm-ceill-floorl-roundl-truncl.patch of Package glibc
From 022abaeacbc85d8409bad22375b16a8c07d3ae39 Mon Sep 17 00:00:00 2001
From: Aurelien Jarno <aurelien@aurel32.net>
Date: Tue, 20 Jan 2026 18:25:08 +0100
Subject: [PATCH] Fix ldbl-128ibm ceill, floorl, roundl and truncl zero-sign
handling
When the result of ceill, floorl, roundl and truncl is zero, the sign of
the result must match the sign of the input. For the IBM 128-bit long
double format, the sign is determined by the high part.
Ensure the correct sign when the high part is the result of
computations, by copying the sign from the input high part to the output
high part. On POWER, this conveniently maps to the fcpsgn instruction.
In addition add test for the values provided in BZ #33623, and for the
opposite value when the result is 0.
Fixes: BZ #33623
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
(cherry picked from commit 6f4b28b20aa9161aeb42a7f34f4d3b96194e5666)
---
NEWS | 2 ++
math/libm-test-ceil.inc | 3 +++
math/libm-test-floor.inc | 3 +++
math/libm-test-round.inc | 4 ++++
math/libm-test-trunc.inc | 4 ++++
sysdeps/ieee754/ldbl-128ibm/s_ceill.c | 3 +++
sysdeps/ieee754/ldbl-128ibm/s_floorl.c | 3 +++
sysdeps/ieee754/ldbl-128ibm/s_roundl.c | 3 +++
sysdeps/ieee754/ldbl-128ibm/s_truncl.c | 3 +++
9 files changed, 28 insertions(+)
diff --git a/math/libm-test-ceil.inc b/math/libm-test-ceil.inc
index a471b43932..48be68cf91 100644
--- a/math/libm-test-ceil.inc
+++ b/math/libm-test-ceil.inc
@@ -79,6 +79,9 @@ static const struct test_f_f_data ceil_test_data[] =
TEST_f_f (ceil, -max_value, -max_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
#if MANT_DIG >= 64
+ /* The input value can only be represented in long double. */
+ TEST_f_f (ceil, -0x0.ffffffffffffffffp0L, minus_zero, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+
/* The result can only be represented in long double. */
TEST_f_f (ceil, 4503599627370495.5L, 4503599627370496.0L, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (ceil, 4503599627370496.25L, 4503599627370497.0L, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
diff --git a/math/libm-test-floor.inc b/math/libm-test-floor.inc
index dee4afff7a..bc945a6c22 100644
--- a/math/libm-test-floor.inc
+++ b/math/libm-test-floor.inc
@@ -79,6 +79,9 @@ static const struct test_f_f_data floor_test_data[] =
TEST_f_f (floor, -max_value, -max_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
#if MANT_DIG >= 64
+ /* The input value can only be represented in long double. */
+ TEST_f_f (floor, 0x0.ffffffffffffffffp0L, plus_zero, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+
/* The result can only be represented in long double. */
TEST_f_f (floor, 4503599627370495.5L, 4503599627370495.0L, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (floor, 4503599627370496.25L, 4503599627370496.0L, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
diff --git a/math/libm-test-round.inc b/math/libm-test-round.inc
index 898ff3791b..1395c51d5d 100644
--- a/math/libm-test-round.inc
+++ b/math/libm-test-round.inc
@@ -99,6 +99,10 @@ static const struct test_f_f_data round_test_data[] =
#endif
#if MANT_DIG >= 64
+ /* The input value can only be represented in long double. */
+ TEST_f_f (round, 0x0.ffffffffffffffffp-1L, plus_zero, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_f_f (round, -0x0.ffffffffffffffffp-1L, minus_zero, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+
/* The result can only be represented in long double. */
TEST_f_f (round, 4503599627370495.5L, 4503599627370496.0L, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (round, 4503599627370496.25L, 4503599627370496.0L, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
diff --git a/math/libm-test-trunc.inc b/math/libm-test-trunc.inc
index 7df741f3ba..5d69cd4b5b 100644
--- a/math/libm-test-trunc.inc
+++ b/math/libm-test-trunc.inc
@@ -91,6 +91,10 @@ static const struct test_f_f_data trunc_test_data[] =
TEST_f_f (trunc, -4294967296.625L, -4294967296.0L, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
#if MANT_DIG >= 64
+ /* The input value can only be represented in long double. */
+ TEST_f_f (trunc, 0x0.ffffffffffffffffp0L, plus_zero, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+ TEST_f_f (trunc, -0x0.ffffffffffffffffp0L, minus_zero, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+
/* The result can only be represented in long double. */
TEST_f_f (trunc, 4503599627370495.5L, 4503599627370495.0L, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_f_f (trunc, 4503599627370496.25L, 4503599627370496.0L, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
diff --git a/sysdeps/ieee754/ldbl-128ibm/s_ceill.c b/sysdeps/ieee754/ldbl-128ibm/s_ceill.c
index 8038cf9fda..88bc364db5 100644
--- a/sysdeps/ieee754/ldbl-128ibm/s_ceill.c
+++ b/sysdeps/ieee754/ldbl-128ibm/s_ceill.c
@@ -54,6 +54,9 @@ __ceill (long double x)
xh = hi;
xl = lo;
ldbl_canonicalize_int (&xh, &xl);
+
+ /* Ensure we return -0 rather than +0 when appropriate. */
+ xh = copysign (xh, hi);
}
}
else
diff --git a/sysdeps/ieee754/ldbl-128ibm/s_floorl.c b/sysdeps/ieee754/ldbl-128ibm/s_floorl.c
index 23f45b773f..4a8294cc78 100644
--- a/sysdeps/ieee754/ldbl-128ibm/s_floorl.c
+++ b/sysdeps/ieee754/ldbl-128ibm/s_floorl.c
@@ -54,6 +54,9 @@ __floorl (long double x)
xh = hi;
xl = lo;
ldbl_canonicalize_int (&xh, &xl);
+
+ /* Ensure we return -0 rather than +0 when appropriate. */
+ xh = copysign (xh, hi);
}
}
else
diff --git a/sysdeps/ieee754/ldbl-128ibm/s_roundl.c b/sysdeps/ieee754/ldbl-128ibm/s_roundl.c
index e8948a0c05..340a63c76a 100644
--- a/sysdeps/ieee754/ldbl-128ibm/s_roundl.c
+++ b/sysdeps/ieee754/ldbl-128ibm/s_roundl.c
@@ -80,6 +80,9 @@ __roundl (long double x)
xh = hi;
ldbl_canonicalize_int (&xh, &xl);
}
+
+ /* Ensure we return -0 rather than +0 when appropriate. */
+ xh = copysign(xh, hi);
}
else
/* Quiet signaling NaN arguments. */
diff --git a/sysdeps/ieee754/ldbl-128ibm/s_truncl.c b/sysdeps/ieee754/ldbl-128ibm/s_truncl.c
index 7f0b77cd3f..21ecbd0c85 100644
--- a/sysdeps/ieee754/ldbl-128ibm/s_truncl.c
+++ b/sysdeps/ieee754/ldbl-128ibm/s_truncl.c
@@ -56,6 +56,9 @@ __truncl (long double x)
xh = hi;
xl = lo;
ldbl_canonicalize_int (&xh, &xl);
+
+ /* Ensure we return -0 rather than +0 when appropriate. */
+ xh = copysign (xh, hi);
}
}
else
--
2.53.0
