commit a3799ae3f5dd6648040d499224cc6dea61b355dd
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Mon Sep 19 18:51:28 2022 +0300

    Fix negative NaN issue on RiscV.

diff --git a/ChangeLog b/ChangeLog
index 35941d0a..d751baf1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,0 +1,6 @@
+2022-09-19         Arnold D. Robbins     <arnold@skeeve.com>
+
+	* eval.c (fix_nan_sign): New function. See bug list citation
+	in the code.
+	* interpret.h (r_interpret): Use it for plus and minus cases.
+
diff --git a/eval.c b/eval.c
index 1069570b..3bfff0ca 100644
--- a/eval.c
+++ b/eval.c
@@ -39,6 +39,8 @@ static int num_exec_hook = 0;
 static Func_pre_exec pre_execute[MAX_EXEC_HOOKS];
 static Func_post_exec post_execute = NULL;
 
+static double fix_nan_sign(double left, double right, double result);
+
 extern void frame_popped();
 
 int OFSlen;
@@ -1901,3 +1903,20 @@ elem_new_to_scalar(NODE *n)
 
 	return n;
 }
+
+/* fix_nan_sign --- fix NaN sign on RiscV */
+
+// See the thread starting at
+// https://lists.gnu.org/archive/html/bug-gawk/2022-09/msg00005.html
+// for why we need this function.
+
+static double
+fix_nan_sign(double left, double right, double result)
+{
+	if (isnan(left) && signbit(left))
+		return copysign(result, -1.0);
+	else if (isnan(right) && signbit(right))
+		return copysign(result, -1.0);
+	else
+		return result;
+}
diff --git a/interpret.h b/interpret.h
index 26010ada..955d918f 100644
--- a/interpret.h
+++ b/interpret.h
@@ -583,6 +583,7 @@ uninitialized_scalar:
 plus:
 			t1 = TOP_NUMBER();
 			r = make_number(t1->numbr + x2);
+			r->numbr = fix_nan_sign(t1->numbr, x2, r->numbr);
 			DEREF(t1);
 			REPLACE(r);
 			break;
@@ -597,6 +598,7 @@ plus:
 minus:
 			t1 = TOP_NUMBER();
 			r = make_number(t1->numbr - x2);
+			r->numbr = fix_nan_sign(t1->numbr, x2, r->numbr);
 			DEREF(t1);
 			REPLACE(r);
 			break;