Index: gcc/match.pd
===================================================================
--- gcc/match.pd	(revision 222062)
+++ gcc/match.pd	(working copy)
@@ -925,20 +925,29 @@ along with GCC; see the file COPYING3.
      (ncmp @0 @1)))))
  (simplify
   (bit_xor (cmp @0 @1) integer_truep)
   (with { enum tree_code ic = invert_tree_comparison
             (cmp, HONOR_NANS (@0)); }
    (if (ic == icmp)
     (icmp @0 @1))
    (if (ic == ncmp)
     (ncmp @0 @1)))))
 
+/* Unordered tests if either argument is a NaN.  */
+(simplify
+ (bit_ior (unordered @0 @0) (unordered @1 @1))
+ (if ((GIMPLE && types_compatible_p (TREE_TYPE (@0), TREE_TYPE (@1)))
+      || (GENERIC && TREE_TYPE (@0) == TREE_TYPE (@1)))
+  (unordered @0 @1)))
+(simplify
+ (bit_ior:c (unordered @0 @0) (unordered:c@2 @0 @1))
+ @2)
 
 /* Simplification of math builtins.  */
 
 (define_operator_list LOG BUILT_IN_LOGF BUILT_IN_LOG BUILT_IN_LOGL)
 (define_operator_list EXP BUILT_IN_EXPF BUILT_IN_EXP BUILT_IN_EXPL)
 (define_operator_list LOG2 BUILT_IN_LOG2F BUILT_IN_LOG2 BUILT_IN_LOG2L)
 (define_operator_list EXP2 BUILT_IN_EXP2F BUILT_IN_EXP2 BUILT_IN_EXP2L)
 (define_operator_list LOG10 BUILT_IN_LOG10F BUILT_IN_LOG10 BUILT_IN_LOG10L)
 (define_operator_list EXP10 BUILT_IN_EXP10F BUILT_IN_EXP10 BUILT_IN_EXP10L)
 (define_operator_list POW BUILT_IN_POWF BUILT_IN_POW BUILT_IN_POWL)
Index: gcc/testsuite/gcc.dg/pr63387.c
===================================================================
--- gcc/testsuite/gcc.dg/pr63387.c	(revision 0)
+++ gcc/testsuite/gcc.dg/pr63387.c	(working copy)
@@ -0,0 +1,26 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-optimized" } */
+
+int f(double aaa, double bbb){
+  int xa = __builtin_isunordered(aaa, aaa);
+  int xb = __builtin_isunordered(bbb, bbb);
+  return xa | xb;
+}
+
+int g(double aaa, double bbb){
+  int xa = __builtin_isunordered(aaa, bbb);
+  int xb = __builtin_isunordered(bbb, bbb);
+  return xa | xb;
+}
+
+int h(double ccc, float ddd){
+  int xc = __builtin_isunordered(ccc, ccc);
+  int xd = __builtin_isunordered(ddd, ddd);
+  return xc | xd;
+}
+
+/* { dg-final { scan-tree-dump-not "aaa\[^\n\r\]* unord aaa" "optimized" } } */
+/* { dg-final { scan-tree-dump-not "bbb\[^\n\r\]* unord bbb" "optimized" } } */
+/* { dg-final { scan-tree-dump-times "aaa\[^\n\r\]* unord bbb" 2 "optimized" } } */
+/* { dg-final { scan-tree-dump-not "ccc\[^\n\r\]* unord ddd" "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */