Fixes regression introduced by glibc-rh1869380.patch.  This fix
backports the upstream fixed implementation of __isnanl to use only in
printf_fp.c so that the fix remains localized and does not affect
other callers of __isnanl.

diff --git a/include/math.h b/include/math.h
index 0925d604ea3552a7..4eddc81be0dccad9 100644
--- a/include/math.h
+++ b/include/math.h
@@ -6,6 +6,11 @@
 /* Now define the internal interfaces.  */
 extern int __matherr (struct exception *__exc);
 
+# if IS_IN (libc)
+extern int __isnanl_pseudo (long double);
+hidden_proto (__isnanl_pseudo)
+#endif
+
 # if IS_IN (libc) || IS_IN (libm)
 hidden_proto (__finite)
 hidden_proto (__isinf)
diff --git a/stdio-common/printf_fp.c b/stdio-common/printf_fp.c
index 60b143571065a082..af842156eaa3eace 100644
--- a/stdio-common/printf_fp.c
+++ b/stdio-common/printf_fp.c
@@ -155,19 +155,7 @@ static __always_inline int
 isnanl_or_pseudo (long double in)
 {
 #if defined __x86_64__ || defined __i386__
-  union
-    {
-      long double f;
-      struct
-	{
-	  uint64_t low;
-	  uint64_t high;
-	} u;
-    } ldouble;
-
-  ldouble.f = in;
-
-  return __isnanl (in) || (ldouble.u.low & 0x8000000000000000) == 0;
+  return __isnanl_pseudo (in);
 #else
   return __isnanl (in);
 #endif
diff --git a/sysdeps/i386/fpu/s_isnanl.c b/sysdeps/i386/fpu/s_isnanl.c
index 816396d8fbc79dde..dc83d7a85fb3318b 100644
--- a/sysdeps/i386/fpu/s_isnanl.c
+++ b/sysdeps/i386/fpu/s_isnanl.c
@@ -41,3 +41,23 @@ int __isnanl(long double x)
 }
 hidden_def (__isnanl)
 weak_alias (__isnanl, isnanl)
+
+#if IS_IN (libc)
+/* Exact backport from glibc-2.33, used only in printf_fp.c.  */
+int __isnanl_pseudo (long double x)
+{
+	int32_t se,hx,lx,pn;
+	GET_LDOUBLE_WORDS(se,hx,lx,x);
+	se = (se & 0x7fff) << 1;
+	/* Detect pseudo-normal numbers, i.e. exponent is non-zero and the top
+	   bit of the significand is not set.   */
+	pn = (uint32_t)((~hx & 0x80000000) & (se|(-se)))>>31;
+	/* Clear the significand bit when computing mantissa.  */
+	lx |= hx & 0x7fffffff;
+	se |= (uint32_t)(lx|(-lx))>>31;
+	se = 0xfffe - se;
+
+	return (int)(((uint32_t)(se)) >> 16) | pn;
+}
+hidden_def (__isnanl_pseudo)
+#endif