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-rw-r--r--src/math/__fpclassifyl.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/src/math/__fpclassifyl.c b/src/math/__fpclassifyl.c
index 481c0b94..e41781b6 100644
--- a/src/math/__fpclassifyl.c
+++ b/src/math/__fpclassifyl.c
@@ -13,10 +13,18 @@ int __fpclassifyl(long double x)
int msb = u.i.m>>63;
if (!e && !msb)
return u.i.m ? FP_SUBNORMAL : FP_ZERO;
+ if (e == 0x7fff) {
+ /* The x86 variant of 80-bit extended precision only admits
+ * one representation of each infinity, with the mantissa msb
+ * necessarily set. The version with it clear is invalid/nan.
+ * The m68k variant, however, allows either, and tooling uses
+ * the version with it clear. */
+ if (__BYTE_ORDER == __LITTLE_ENDIAN && !msb)
+ return FP_NAN;
+ return u.i.m << 1 ? FP_NAN : FP_INFINITE;
+ }
if (!msb)
return FP_NAN;
- if (e == 0x7fff)
- return u.i.m << 1 ? FP_NAN : FP_INFINITE;
return FP_NORMAL;
}
#elif LDBL_MANT_DIG == 113 && LDBL_MAX_EXP == 16384