From 93024e94b87c8a1d60ae7da438d4e76bc9ed9c49 Mon Sep 17 00:00:00 2001
From: MITSUNARI Shigeo <herumi@nifty.com>
Date: Tue, 1 Nov 2016 10:31:00 +0900
Subject: [PATCH] don't call AddUnitPre if not necessary

---
 src/fp_proto.hpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/fp_proto.hpp b/src/fp_proto.hpp
index 73fc272..6c54a74 100644
--- a/src/fp_proto.hpp
+++ b/src/fp_proto.hpp
@@ -146,7 +146,10 @@ struct MulPre {
 		c -= SubPre<N, Tag>::f(tmp, tmp, z + N);
 		// c:tmp[N] = ad + bc
 		c += AddPre<N, Tag>::f(z + H, z + H, tmp);
-		AddUnitPre<Tag>::f(z + N + H, H, c);
+		assert(c <= 1);
+		if (c) {
+			AddUnitPre<Tag>::f(z + N + H, H, 1);
+		}
 	}
 	static inline void func(Unit *z, const Unit *x, const Unit *y)
 	{