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Remove const from _Atomic vars to make Clang happy

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Clang does not allow using C11's atomic_load on const _Atomic variables.
Previously it just disabled use of C11 atomics if atomic_load didn't work on a
const _Atomic variable, but I think I'd prefer to have Clang use C11 atomics
for the added features (more explicit memory ordering) even if it means a few
instances of breaking const.
This commit is contained in:
Chris Robinson 2017-04-21 16:58:55 -07:00
parent d85177cd3e
commit a0a41921fc
5 changed files with 42 additions and 19 deletions
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2
Alc/ALu.c
View File

@ -1276,7 +1276,7 @@ static void CalcAttnSourceParams(ALvoice *voice, const struct ALvoiceProps *prop
static void CalcSourceParams(ALvoice *voice, ALCcontext *context, ALboolean force)
{
const ALbufferlistitem *BufferListItem;
ALbufferlistitem *BufferListItem;
struct ALvoiceProps *props;
props = ATOMIC_EXCHANGE_PTR(&voice->Update, NULL, almemory_order_acq_rel);

20
Alc/alcRing.c
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@ -103,16 +103,16 @@ void ll_ringbuffer_reset(ll_ringbuffer_t *rb)
* elements in front of the read pointer and behind the write pointer. */
size_t ll_ringbuffer_read_space(const ll_ringbuffer_t *rb)
{
size_t w = ATOMIC_LOAD(&rb->write_ptr, almemory_order_acquire) & rb->size_mask;
size_t r = ATOMIC_LOAD(&rb->read_ptr, almemory_order_acquire) & rb->size_mask;
size_t w = ATOMIC_LOAD(&CONST_CAST(ll_ringbuffer_t*,rb)->write_ptr, almemory_order_acquire);
size_t r = ATOMIC_LOAD(&CONST_CAST(ll_ringbuffer_t*,rb)->read_ptr, almemory_order_acquire);
return (w-r) & rb->size_mask;
}
/* Return the number of elements available for writing. This is the number of
* elements in front of the write pointer and behind the read pointer. */
size_t ll_ringbuffer_write_space(const ll_ringbuffer_t *rb)
{
size_t w = ATOMIC_LOAD(&rb->write_ptr, almemory_order_acquire) & rb->size_mask;
size_t r = ATOMIC_LOAD(&rb->read_ptr, almemory_order_acquire) & rb->size_mask;
size_t w = ATOMIC_LOAD(&CONST_CAST(ll_ringbuffer_t*,rb)->write_ptr, almemory_order_acquire);
size_t r = ATOMIC_LOAD(&CONST_CAST(ll_ringbuffer_t*,rb)->read_ptr, almemory_order_acquire);
return (r-w-1) & rb->size_mask;
}
@ -256,8 +256,10 @@ void ll_ringbuffer_get_read_vector(const ll_ringbuffer_t *rb, ll_ringbuffer_data
size_t cnt2;
size_t w, r;
w = ATOMIC_LOAD(&rb->write_ptr, almemory_order_acquire) & rb->size_mask;
r = ATOMIC_LOAD(&rb->read_ptr, almemory_order_acquire) & rb->size_mask;
w = ATOMIC_LOAD(&CONST_CAST(ll_ringbuffer_t*,rb)->write_ptr, almemory_order_acquire);
r = ATOMIC_LOAD(&CONST_CAST(ll_ringbuffer_t*,rb)->read_ptr, almemory_order_acquire);
w &= rb->size_mask;
r &= rb->size_mask;
free_cnt = (w-r) & rb->size_mask;
cnt2 = r + free_cnt;
@ -289,8 +291,10 @@ void ll_ringbuffer_get_write_vector(const ll_ringbuffer_t *rb, ll_ringbuffer_dat
size_t cnt2;
size_t w, r;
w = ATOMIC_LOAD(&rb->write_ptr, almemory_order_acquire) & rb->size_mask;
r = ATOMIC_LOAD(&rb->read_ptr, almemory_order_acquire) & rb->size_mask;
w = ATOMIC_LOAD(&CONST_CAST(ll_ringbuffer_t*,rb)->write_ptr, almemory_order_acquire);
r = ATOMIC_LOAD(&CONST_CAST(ll_ringbuffer_t*,rb)->read_ptr, almemory_order_acquire);
w &= rb->size_mask;
r &= rb->size_mask;
free_cnt = (r-w-1) & rb->size_mask;
cnt2 = w + free_cnt;

7
CMakeLists.txt
View File

@ -264,12 +264,11 @@ HAVE_C11_ALIGNAS)
# Check if we have C11 _Atomic
CHECK_C_SOURCE_COMPILES(
"#include <stdatomic.h>
const int _Atomic foo = ATOMIC_VAR_INIT(~0);
int _Atomic bar = ATOMIC_VAR_INIT(0);
int _Atomic foo = ATOMIC_VAR_INIT(0);
int main()
{
atomic_fetch_add(&bar, 2);
return atomic_load(&foo);
atomic_fetch_add(&foo, 2);
return 0;
}"
HAVE_C11_ATOMIC)

14
OpenAL32/Include/alMain.h
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@ -204,6 +204,20 @@ AL_API const ALchar* AL_APIENTRY alGetStringiSOFT(ALenum pname, ALsizei index);
#endif
#ifdef __GNUC__
/* This helps cast away the const-ness of a pointer without accidentally
* changing the pointer type. This is necessary due to Clang's inability to use
* atomic_load on a const _Atomic variable.
*/
#define CONST_CAST(T, V) __extension__({ \
const T _tmp = (V); \
(T)_tmp; \
})
#else
#define CONST_CAST(T, V) ((T)(V))
#endif
typedef ALint64SOFT ALint64;
typedef ALuint64SOFT ALuint64;

18
OpenAL32/alSource.c
View File

@ -1407,7 +1407,8 @@ static ALboolean GetSourceiv(ALsource *Source, ALCcontext *Context, SourceProp p
while(BufferList && BufferList != Current)
{
played++;
BufferList = ATOMIC_LOAD(&BufferList->next, almemory_order_relaxed);
BufferList = ATOMIC_LOAD(&CONST_CAST(ALbufferlistitem*,BufferList)->next,
almemory_order_relaxed);
}
*values = played;
}
@ -3177,7 +3178,8 @@ static ALint64 GetSourceSampleOffset(ALsource *Source, ALCcontext *context, ALui
{
if(BufferList->buffer)
readPos += (ALuint64)BufferList->buffer->SampleLen << 32;
BufferList = ATOMIC_LOAD(&BufferList->next, almemory_order_relaxed);
BufferList = ATOMIC_LOAD(&CONST_CAST(ALbufferlistitem*,BufferList)->next,
almemory_order_relaxed);
}
readPos = minu64(readPos, U64(0x7fffffffffffffff));
}
@ -3233,13 +3235,15 @@ static ALdouble GetSourceSecOffset(ALsource *Source, ALCcontext *context, ALuint
if(!BufferFmt) BufferFmt = buffer;
readPos += (ALuint64)buffer->SampleLen << FRACTIONBITS;
}
BufferList = ATOMIC_LOAD(&BufferList->next, almemory_order_relaxed);
BufferList = ATOMIC_LOAD(&CONST_CAST(ALbufferlistitem*,BufferList)->next,
almemory_order_relaxed);
}
while(BufferList && !BufferFmt)
{
BufferFmt = BufferList->buffer;
BufferList = ATOMIC_LOAD(&BufferList->next, almemory_order_relaxed);
BufferList = ATOMIC_LOAD(&CONST_CAST(ALbufferlistitem*,BufferList)->next,
almemory_order_relaxed);
}
assert(BufferFmt != NULL);
@ -3302,7 +3306,8 @@ static ALdouble GetSourceOffset(ALsource *Source, ALenum name, ALCcontext *conte
totalBufferLen += buffer->SampleLen;
if(!readFin) readPos += buffer->SampleLen;
}
BufferList = ATOMIC_LOAD(&BufferList->next, almemory_order_relaxed);
BufferList = ATOMIC_LOAD(&CONST_CAST(ALbufferlistitem*,BufferList)->next,
almemory_order_relaxed);
}
assert(BufferFmt != NULL);
@ -3421,7 +3426,8 @@ static ALboolean GetSampleOffset(ALsource *Source, ALuint *offset, ALsizei *frac
{
if((BufferFmt=BufferList->buffer) != NULL)
break;
BufferList = ATOMIC_LOAD(&BufferList->next, almemory_order_relaxed);
BufferList = ATOMIC_LOAD(&CONST_CAST(ALbufferlistitem*,BufferList)->next,
almemory_order_relaxed);
}
if(!BufferFmt)
{