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Root all strings and objects first when unboxing. Then box values that might trigger the GC (doubles/ints). This probably needs some performance tuning over time.

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This commit is contained in:
Andreas Gal 2008-07-10 13:24:49 -07:00
parent e42a82831b
commit 6f69a35718
1 changed files with 23 additions and 9 deletions
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32
js/src/jstracer.cpp
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@ -668,9 +668,8 @@ box_jsval(JSContext* cx, jsval& v, uint8 t, double* slot)
if (JSDOUBLE_IS_INT(d, i))
goto store_int;
store_double:
/* GC is not allowed to hit as we come out of the native frame. We have to teach
the GC how to scan native frames to avoid this race condition. */
JS_ASSERT(cx->doubleFreeList != NULL);
/* Its safe to trigger the GC here since we rooted all strings/objects and all the
doubles we already processed. */
return js_NewDoubleInRootedValue(cx, d, &v);
case JSVAL_STRING:
v = STRING_TO_JSVAL(*(JSString**)slot);
@ -688,13 +687,15 @@ box_jsval(JSContext* cx, jsval& v, uint8 t, double* slot)
/* Attempt to unbox the given JS frame into a native frame, checking along the way that the
supplied typemap holds. */
static bool
unbox(JSStackFrame* entryFrame, JSStackFrame* currentFrame, uint8* m, double* native)
unbox(JSStackFrame* entryFrame, JSStackFrame* currentFrame, uint8* map, double* native)
{
verbose_only(printf("unbox native@%p ", native);)
double* np = native;
uint8* mp = map;
FORALL_SLOTS_IN_PENDING_FRAMES(entryFrame, currentFrame,
if (vp && !unbox_jsval(*vp, *m, native))
if (vp && !unbox_jsval(*vp, *mp, np))
return false;
++m; ++native
++mp; ++np;
);
verbose_only(printf("\n");)
return true;
@ -703,13 +704,26 @@ unbox(JSStackFrame* entryFrame, JSStackFrame* currentFrame, uint8* m, double* na
/* Box the given native frame into a JS frame. This only fails due to a hard error
(out of memory for example). */
static bool
box(JSContext* cx, JSStackFrame* entryFrame, JSStackFrame* currentFrame, uint8* m, double* native)
box(JSContext* cx, JSStackFrame* entryFrame, JSStackFrame* currentFrame, uint8* map, double* native)
{
verbose_only(printf("box native@%p ", native);)
double* np = native;
uint8* mp = map;
/* Root all string and object references first (we don't need to call the GC for this). */
FORALL_SLOTS_IN_PENDING_FRAMES(entryFrame, currentFrame,
if (vp && !box_jsval(cx, *vp, *m, native))
if (vp && (*mp == JSVAL_STRING || *mp == JSVAL_OBJECT) && !box_jsval(cx, *vp, *mp, np))
return false;
++m; ++native
++mp; ++np
);
/* Now do this again but this time for all values (properly quicker than actually checking
the type and excluding strings and objects). The GC might kick in when we store doubles,
but everything is rooted now (all strings/objects and all doubles we already boxed). */
np = native;
mp = map;
FORALL_SLOTS_IN_PENDING_FRAMES(entryFrame, currentFrame,
if (vp && !box_jsval(cx, *vp, *mp, np))
return false;
++mp; ++np
);
verbose_only(printf("\n");)
return true;