NaN-packing changes for interpreter.

1 files changed, 23 insertions, 0 deletions

diff --git a/src/test/values.zig b/src/test/values.zig
index 968a5bc..a276b2e 100644
--- a/src/test/values.zig
+++ b/src/test/values.zig
@@ -42,6 +42,29 @@ test "fixnum" {
     try testing.expectEqual(int1 + int2, result);
 }
 
+test "snan" {
+    // Can speculative execution screw up sNaN handling?
+    const v1 = value.fixnum.pack(1234);
+    const v2 = value.fixnum.pack(1234);
+
+    // Even executing this unconditionally doesn't seem to cause issues on my
+    // machine, so it's not clear how to best test this.
+    //const f = v1.double + v2.double;
+    //std.debug.print("oh no! {}\n", .{f});
+
+    if (v1.isDouble() and v2.isDouble()) {
+        @branchHint(.likely);
+        // This actually doesn't even cause any issues if you execute it
+        // unconditionally.  It just prints the NaN value.
+        const fl = v1.double + v2.double;
+        std.debug.print("oh no! {}\n", .{fl});
+    } else {
+        @branchHint(.cold);
+        const v3 = value.fixnum.add(v1, v2);
+        try testing.expectEqual(value.fixnum.unpack(v3), 2468);
+    }
+}
+
 test "ptr" {
     const ptr = value.ptr;