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Work around C11 const atomic restrictions. 

Cast away the const qualifier in BBinder::findObject.  C11, unlike C++11,
does not allow loads from const atomics.  This is widely regarded as
a bug (see WG14 DR 459).  This is a hack to work around it until it's
officially fixed in the spec.

load_const_atomic was adapted from commit
1e8587a479fd8b1ce9b594298a93f517816e8f15

I don't think we want to dignify this by putting it into a header file.

Bug:17067219
Change-Id: Icbfcbda2722e6f80d2bb065a0bb3ec7634bcacb2
This commit is contained in:
Hans Boehm 2014-09-11 14:49:09 -07:00
parent 7d587c31d5
commit c0df68bb80
1 changed files with 9 additions and 1 deletions
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10
libs/binder/Binder.cpp
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@ -160,10 +160,18 @@ void BBinder::attachObject(
e->mObjects.attach(objectID, object, cleanupCookie, func);
}
// The C11 standard doesn't allow atomic loads from const fields,
// though C++11 does. Fudge it until standards get straightened out.
static inline uintptr_t load_const_atomic(const atomic_uintptr_t* p,
memory_order mo) {
atomic_uintptr_t* non_const_p = const_cast<atomic_uintptr_t*>(p);
return atomic_load_explicit(non_const_p, mo);
}
void* BBinder::findObject(const void* objectID) const
{
Extras* e = reinterpret_cast<Extras*>(
atomic_load_explicit(&mExtras, memory_order_acquire));
load_const_atomic(&mExtras, memory_order_acquire));
if (!e) return NULL;
AutoMutex _l(e->mLock);