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Bug 497794. Don't allocate two copies of the image data when doing GetImageData/CreateImageData, just to throw one away immediately. r=robarnold,jwalden

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This commit is contained in:
Boris Zbarsky
2009-10-26 16:57:41 -04:00
parent a2688e9153
commit 879dcafc42
3 changed files with 85 additions and 36 deletions
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56
js/src/jsarray.cpp
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@@ -309,7 +309,8 @@ BigIndexToId(JSContext *cx, JSObject *obj, jsuint index, JSBool createAtom,
}
static JSBool
ResizeSlots(JSContext *cx, JSObject *obj, uint32 oldlen, uint32 newlen)
ResizeSlots(JSContext *cx, JSObject *obj, uint32 oldlen, uint32 newlen,
bool initializeAllSlots = true)
{
jsval *slots, *newslots;
@@ -334,8 +335,10 @@ ResizeSlots(JSContext *cx, JSObject *obj, uint32 oldlen, uint32 newlen)
obj->dslots = newslots + 1;
js_SetDenseArrayCapacity(obj, newlen);
for (slots = obj->dslots + oldlen; slots < obj->dslots + newlen; slots++)
*slots = JSVAL_HOLE;
if (initializeAllSlots) {
for (slots = obj->dslots + oldlen; slots < obj->dslots + newlen; slots++)
*slots = JSVAL_HOLE;
}
return JS_TRUE;
}
@@ -356,7 +359,8 @@ ResizeSlots(JSContext *cx, JSObject *obj, uint32 oldlen, uint32 newlen)
#define CAPACITY_CHUNK (1024 * 1024 / sizeof(jsval))
static JSBool
EnsureCapacity(JSContext *cx, JSObject *obj, uint32 newcap)
EnsureCapacity(JSContext *cx, JSObject *obj, uint32 newcap,
bool initializeAllSlots = true)
{
uint32 oldcap = js_DenseArrayCapacity(obj);
@@ -375,12 +379,23 @@ EnsureCapacity(JSContext *cx, JSObject *obj, uint32 newcap)
? oldcap * 2 + 1
: oldcap + (oldcap >> 3);
newcap = JS_MAX(newcap, nextsize);
if (newcap >= CAPACITY_CHUNK)
newcap = JS_ROUNDUP(newcap + 1, CAPACITY_CHUNK) - 1; /* -1 for dslots[-1] */
else if (newcap < ARRAY_CAPACITY_MIN)
newcap = ARRAY_CAPACITY_MIN;
return ResizeSlots(cx, obj, oldcap, newcap);
uint32 actualCapacity = JS_MAX(newcap, nextsize);
if (actualCapacity >= CAPACITY_CHUNK)
actualCapacity = JS_ROUNDUP(actualCapacity + 1, CAPACITY_CHUNK) - 1; /* -1 for dslots[-1] */
else if (actualCapacity < ARRAY_CAPACITY_MIN)
actualCapacity = ARRAY_CAPACITY_MIN;
if (!ResizeSlots(cx, obj, oldcap, actualCapacity, initializeAllSlots))
return JS_FALSE;
if (!initializeAllSlots) {
/*
* Initialize the slots caller didn't actually ask for.
*/
for (jsval *slots = obj->dslots + newcap;
slots < obj->dslots + actualCapacity;
slots++) {
*slots = JSVAL_HOLE;
}
}
}
return JS_TRUE;
}
@@ -3568,3 +3583,24 @@ js_CoerceArrayToCanvasImageData(JSObject *obj, jsuint offset, jsuint count,
return JS_TRUE;
}
JS_FRIEND_API(JSObject *)
js_NewArrayObjectWithCapacity(JSContext *cx, jsuint capacity, jsval **vector)
{
JSObject *obj = js_NewArrayObject(cx, capacity, NULL);
if (!obj)
return NULL;
JSAutoTempValueRooter tvr(cx, obj);
if (!EnsureCapacity(cx, obj, capacity, JS_FALSE))
obj = NULL;
/* Set/clear newborn root, in case we lost it. */
cx->weakRoots.finalizableNewborns[FINALIZE_OBJECT] = obj;
if (!obj)
return NULL;
obj->fslots[JSSLOT_ARRAY_COUNT] = capacity;
*vector = obj->dslots;
return obj;
}