From 0887d82406c9a9701acd235e8f510480cea9f218 Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Wed, 10 Sep 2025 00:23:56 +0900
Subject: [PATCH] dtoa.c: Add shortcut if arguments are zero

---
 missing/dtoa.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/missing/dtoa.c b/missing/dtoa.c
index 8859fcfa44..4d266ecf12 100644
--- a/missing/dtoa.c
+++ b/missing/dtoa.c
@@ -699,6 +699,8 @@ i2b(int i)
     return b;
 }
 
+#define Bzero_p(b) (!(b)->x[0] && (b)->wds <= 1)
+
 static Bigint *
 mult(Bigint *a, Bigint *b)
 {
@@ -715,6 +717,13 @@ mult(Bigint *a, Bigint *b)
 #endif
 #endif
 
+    if (Bzero_p(a) || Bzero_p(b)) {
+        c = Balloc(0);
+        c->wds = 1;
+        c->x[0] = 0;
+        return c;
+    }
+
     if (a->wds < b->wds) {
         c = a;
         a = b;
@@ -862,6 +871,8 @@ lshift(Bigint *b, int k)
     Bigint *b1;
     ULong *x, *x1, *xe, z;
 
+    if (!k || Bzero_p(b)) return b;
+
 #ifdef Pack_32
     n = k >> 5;
 #else