Eric Blake <ebb9 <at> byu.net> writes:
>
> Here's one idea. Since it fixes the mingw cross-compilation failure of test-
> isnanl-nolibm, I'm installing it; if we come up with something better or more
> efficient in the future, we can alter the test then.
>
> The idea behind this patch is that = doesn't alter the bit pattern of an
> invalid representation that sneaks past the == check, but +0 will result in a
> normalized bit pattern, so that the memcmp can then filter out pseudo-
> denormals. For all valid bit patterns, the == already filtered out NaN, so
> adding +0.0 is a no-op to the bit pattern. Here's a snippet of my gdb
session
> on mingw that shows this point (where sizeof(long double) is 12):
That fix was insufficient, since it failed on isnan(-0.0L) (-0.0 + 0.0 is +0.0,
not -0.0, not to mention that the padding bits in m1 and m2 were uninitialized
and could differ). Since the failure on -0.0L wasn't caught until the test-
vasprintf-posix test, I'm augmenting test-isnan* to actually try this case.
From: Eric Blake <[EMAIL PROTECTED]>
Date: Tue, 11 Dec 2007 14:00:26 -0700
Subject: [PATCH] Fix bug with -0.0L in previous patch.
* lib/isnan.c (rpl_isnanl): Make robust to -0.0L and pad bits.
* tests/test-isnan.c (main): Also test on zeroes.
* tests/test-isnanf.c (main): Likewise.
* tests/test-isnanl.h (main): Likewise.
Signed-off-by: Eric Blake <[EMAIL PROTECTED]>
---
ChangeLog | 6 ++++++
lib/isnan.c | 4 +++-
tests/test-isnan.c | 2 ++
tests/test-isnanf.c | 2 ++
tests/test-isnanl.h | 2 ++
5 files changed, 15 insertions(+), 1 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 127f9a5..a954c4c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
2007-12-11 Eric Blake <[EMAIL PROTECTED]>
+ Fix bug with -0.0L in previous patch.
+ * lib/isnan.c (rpl_isnanl): Make robust to -0.0L and pad bits.
+ * tests/test-isnan.c (main): Also test on zeroes.
+ * tests/test-isnanf.c (main): Likewise.
+ * tests/test-isnanl.h (main): Likewise.
+
Detect pseudo-denormals on x86 even when cross-compiling.
* lib/isnan.c (rpl_isnanl) [!KNOWN_EXPBIT0_LOCATION
&& USE_LONG_DOUBLE && x86]: Add one more check to filter out
diff --git a/lib/isnan.c b/lib/isnan.c
index 182a7bd..04bf7f0 100644
--- a/lib/isnan.c
+++ b/lib/isnan.c
@@ -146,8 +146,10 @@ FUNC (DOUBLE x)
memory_double m1;
memory_double m2;
+ memset (&m1.value, 0, SIZE);
+ memset (&m2.value, 0, SIZE);
m1.value = x;
- m2.value = x + 0;
+ m2.value = x + (x ? 0.0L : -0.0L);
if (memcmp (&m1.value, &m2.value, SIZE) != 0)
return 1;
# endif
diff --git a/tests/test-isnan.c b/tests/test-isnan.c
index 717ad7a..3541af4 100644
--- a/tests/test-isnan.c
+++ b/tests/test-isnan.c
@@ -57,6 +57,8 @@ main ()
ASSERT (!isnan (-2.718));
ASSERT (!isnan (-2.718e30));
ASSERT (!isnan (-2.718e-30));
+ ASSERT (!isnan (0.0));
+ ASSERT (!isnan (-0.0));
/* Infinite values. */
ASSERT (!isnan (1.0 / 0.0));
ASSERT (!isnan (-1.0 / 0.0));
diff --git a/tests/test-isnanf.c b/tests/test-isnanf.c
index 898e6ed..c433089 100644
--- a/tests/test-isnanf.c
+++ b/tests/test-isnanf.c
@@ -57,6 +57,8 @@ main ()
ASSERT (!isnanf (-2.718f));
ASSERT (!isnanf (-2.718e30f));
ASSERT (!isnanf (-2.718e-30f));
+ ASSERT (!isnanf (0.0f));
+ ASSERT (!isnanf (-0.0f));
/* Infinite values. */
ASSERT (!isnanf (1.0f / 0.0f));
ASSERT (!isnanf (-1.0f / 0.0f));
diff --git a/tests/test-isnanl.h b/tests/test-isnanl.h
index 5885457..657948c 100644
--- a/tests/test-isnanl.h
+++ b/tests/test-isnanl.h
@@ -47,6 +47,8 @@ main ()
ASSERT (!isnanl (-2.718L));
ASSERT (!isnanl (-2.718e30L));
ASSERT (!isnanl (-2.718e-30L));
+ ASSERT (!isnanl (0.0L));
+ ASSERT (!isnanl (-0.0L));
/* Infinite values. */
ASSERT (!isnanl (1.0L / 0.0L));
ASSERT (!isnanl (-1.0L / 0.0L));
--
1.5.3.5
