From 90d0c3316c1bc0f2b904e758a4446c1cd111bc63 Mon Sep 17 00:00:00 2001
From: Robert Griesemer <gri@golang.org>
Date: Tue, 18 May 2010 16:31:49 -0700
Subject: [PATCH] big: bug fix for division

Fixes #784.

R=rsc
CC=golang-dev
https://golang.org/cl/1196043
---
 src/pkg/big/nat.go | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/pkg/big/nat.go b/src/pkg/big/nat.go
index 56f3c444ef4..668a626891d 100755
--- a/src/pkg/big/nat.go
+++ b/src/pkg/big/nat.go
@@ -528,10 +528,15 @@ func (z nat) divLarge(u, uIn, v nat) (q, r nat) {
 	n := len(v)
 	m := len(uIn) - n
 
+	// determine if z can be reused
+	if alias(z, uIn) || alias(z, v) {
+		z = nil // z is an alias for uIn or v - cannot reuse
+	}
 	q = z.make(m + 1)
+
 	qhatv := make(nat, n+1)
-	if alias(u, uIn) {
-		u = nil // u is an alias for uIn - cannot reuse
+	if alias(u, uIn) || alias(u, v) {
+		u = nil // u is an alias for uIn or v - cannot reuse
 	}
 	u = u.make(len(uIn) + 1)
 	u.clear()