[Libclc-dev] [PATCH 1/2] atomic: Add generic bitcode implementation of atomic_max

[Matt Arsenault]

On Sep 8, 2014, at 12:52 PM, Aaron Watry <awatry at gmail.com> wrote:

> From CL v1.2, Section 6.12.11:
> int atomic_max (volatile __global int *p, int val)
> unsigned int atomic_max (volatile __global unsigned int *p, unsigned int val)
> int atomic_max (volatile __local int *p, int val)
> unsigned int atomic_max (volatile __local unsigned int *p, unsigned int val)
> 
> I'm assuming that the pointer declaration as volatile should translate
> directly to the statement in the bitcode.  Let me know if you think I
> mis-understood that.  If that's the case, then we also need to fix the
> atomic_add and atomic_sub functions.

Yes, that’s how I would interpret it.
> 
> And yes, there's a note that the atom_* functions from CL 1.0 are
> still supported. Those functions do NOT define the pointers as
> volatile.

Yes, the sets of atomic functions are separate. It looks like currently atom_add is defined to be the same as atomic_add



> 
> --Aaron
> 
> --Aaron
> 
> 
> On Mon, Sep 8, 2014 at 11:41 AM, Matt Arsenault <arsenm2 at gmail.com> wrote:
>> 
>> On Sep 8, 2014, at 12:31 PM, Aaron Watry <awatry at gmail.com> wrote:
>> 
>>> Not used yet...
>>> 
>>> Signed-off-by: Aaron Watry <awatry at gmail.com>
>>> ---
>>> generic/include/clc/atomic/atomic_max.h |  3 +++
>>> generic/include/clc/clc.h               |  1 +
>>> generic/lib/atomic/atomic_impl.ll       | 12 ++++++++++++
>>> 3 files changed, 16 insertions(+)
>>> create mode 100644 generic/include/clc/atomic/atomic_max.h
>>> 
>>> diff --git a/generic/include/clc/atomic/atomic_max.h b/generic/include/clc/atomic/atomic_max.h
>>> new file mode 100644
>>> index 0000000..30dc180
>>> --- /dev/null
>>> +++ b/generic/include/clc/atomic/atomic_max.h
>>> @@ -0,0 +1,3 @@
>>> +#define __CLC_FUNCTION atomic_max
>>> +#include <clc/atomic/atomic_decl.inc>
>>> +#undef __CLC_FUNCTION
>>> diff --git a/generic/include/clc/clc.h b/generic/include/clc/clc.h
>>> index b8c1cb9..b492c54 100644
>>> --- a/generic/include/clc/clc.h
>>> +++ b/generic/include/clc/clc.h
>>> @@ -143,6 +143,7 @@
>>> #include <clc/atomic/atomic_add.h>
>>> #include <clc/atomic/atomic_dec.h>
>>> #include <clc/atomic/atomic_inc.h>
>>> +#include <clc/atomic/atomic_max.h>
>>> #include <clc/atomic/atomic_sub.h>
>>> 
>>> /* cl_khr_global_int32_base_atomics Extension Functions */
>>> diff --git a/generic/lib/atomic/atomic_impl.ll b/generic/lib/atomic/atomic_impl.ll
>>> index 9df5b9f..4e228e8 100644
>>> --- a/generic/lib/atomic/atomic_impl.ll
>>> +++ b/generic/lib/atomic/atomic_impl.ll
>>> @@ -10,6 +10,18 @@ entry:
>>>  ret i32 %0
>>> }
>>> 
>>> +define i32 @__clc_atomic_max_addr1(i32 addrspace(1)* nocapture %ptr, i32 %value) nounwind alwaysinline {
>>> +entry:
>>> +  %0 = atomicrmw volatile max i32 addrspace(1)* %ptr, i32 %value seq_cst
>>> +  ret i32 %0
>>> +}
>> 
>> Why is it necessary to mark these with volatile (though I never remember whether it’s the atom_* or atomic_* functions which is supposed to be volatile)
>> 
>> 
>>> +
>>> +define i32 @__clc_atomic_max_addr3(i32 addrspace(3)* nocapture %ptr, i32 %value) nounwind alwaysinline {
>>> +entry:
>>> +  %0 = atomicrmw volatile max i32 addrspace(3)* %ptr, i32 %value seq_cst
>>> +  ret i32 %0
>>> +}
>>> +
>>> define i32 @__clc_atomic_sub_addr1(i32 addrspace(1)* nocapture %ptr, i32 %value) nounwind alwaysinline {
>>> entry:
>>>  %0 = atomicrmw volatile sub i32 addrspace(1)* %ptr, i32 %value seq_cst
>>> --
>>> 1.9.1
>>> 
>>> 
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>>