From 3f3dd1a810b166303c3e2aaba168b74f3e4e9691 Mon Sep 17 00:00:00 2001
From: "pavlov%pavlov.net"
 <pavlov%pavlov.net@18797224-902f-48f8-a5cc-f745e15eee43>
Date: Tue, 11 Dec 2007 08:36:29 +0000
Subject: [PATCH] bug 407428. stack allocate small strings in js_XDRStringAtom
 instead of instead of using the tempPool arena to allocate them. 
 r=brendan,igor

git-svn-id: svn://10.0.0.236/trunk@240793 18797224-902f-48f8-a5cc-f745e15eee43
---
 mozilla/js/src/jsxdrapi.c | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/mozilla/js/src/jsxdrapi.c b/mozilla/js/src/jsxdrapi.c
index 0b9146f67e6..ad1aef11646 100644
--- a/mozilla/js/src/jsxdrapi.c
+++ b/mozilla/js/src/jsxdrapi.c
@@ -644,8 +644,8 @@ js_XDRStringAtom(JSXDRState *xdr, JSAtom **atomp)
     uint32 nchars;
     JSAtom *atom;
     JSContext *cx;
-    void *mark;
     jschar *chars;
+    jschar stackChars[256];
 
     if (xdr->mode == JSXDR_ENCODE) {
         JS_ASSERT(ATOM_IS_STRING(*atomp));
@@ -661,14 +661,23 @@ js_XDRStringAtom(JSXDRState *xdr, JSAtom **atomp)
         return JS_FALSE;
     atom = NULL;
     cx = xdr->cx;
-    mark = JS_ARENA_MARK(&cx->tempPool);
-    JS_ARENA_ALLOCATE_CAST(chars, jschar *, &cx->tempPool,
-                           nchars * sizeof(jschar));
-    if (!chars)
-        js_ReportOutOfScriptQuota(cx);
-    else if (XDRChars(xdr, chars, nchars))
+    if (nchars <= JS_ARRAY_LENGTH(stackChars)) {
+        chars = stackChars;
+    } else {
+        /*
+         * This is very uncommon. Don't use the tempPool arena for this as
+         * most allocations here will be bigger than tempPool's arenasize.
+         */
+        chars = (jschar *) JS_malloc(cx, nchars * sizeof(jschar));
+        if (!chars)
+            return JS_FALSE;
+    }
+
+    if (XDRChars(xdr, chars, nchars))
         atom = js_AtomizeChars(cx, chars, nchars, 0);
-    JS_ARENA_RELEASE(&cx->tempPool, mark);
+    if (chars != stackChars)
+        JS_free(cx, chars);
+
     if (!atom)
         return JS_FALSE;
     *atomp = atom;