From 092511bac76a4aca95e15107c67deb16272154c5 Mon Sep 17 00:00:00 2001
From: akr <akr@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Sat, 3 Aug 2013 16:01:14 +0000
Subject: [PATCH] * bignum.c (big2str_karatsuba): Don't allocate new temporary
 buffer   if the buffer is enough for current invocation.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42364 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 ChangeLog | 5 +++++
 bignum.c  | 9 +++++----
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index aff5a024a2..fc0a391c08 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sun Aug  4 00:57:58 2013  Tanaka Akira  <akr@fsij.org>
+
+	* bignum.c (big2str_karatsuba): Don't allocate new temporary buffer
+	  if the buffer is enough for current invocation.
+
 Sun Aug  4 00:22:34 2013  Tanaka Akira  <akr@fsij.org>
 
 	* bignum.c (bary2bdigitdbl): New function.
diff --git a/bignum.c b/bignum.c
index a3e4a0be91..f7599c3449 100644
--- a/bignum.c
+++ b/bignum.c
@@ -4383,12 +4383,13 @@ big2str_karatsuba(struct big2str_struct *b2s, BDIGIT *xds, size_t xn,
             memset(b2s->ptr, '0', len);
             b2s->ptr += len;
         }
-        if (wn < bn * 4 + BIGDIVREM_EXTRA_WORDS) {
-            wn = bn * 4 + BIGDIVREM_EXTRA_WORDS;
-            wds = ALLOCV_N(BDIGIT, tmpw, wn);
-        }
         rn = bn;
         qn = xn+BIGDIVREM_EXTRA_WORDS;
+        if (wn < rn + qn) {
+            wn = bn * 4 + BIGDIVREM_EXTRA_WORDS;
+            assert(rn + qn <= wn);
+            wds = ALLOCV_N(BDIGIT, tmpw, wn);
+        }
         rds = wds;
         qds = wds+rn;
         bary_divmod(qds, qn, rds, rn, xds, xn, bds, bn);