Main changes:
* OpenCL legacy atom/atomic builtins now call CLC atomic functions
(which use Clang __scoped_atomic_*), replacing previous Clang __sync_*
functions.
* Change memory order from seq_cst to relaxed; keep device scope (spec
permits broader than workgroup). LLVM IR for _Z8atom_decPU3AS1Vi in
amdgcn--amdhsa.bc:
Before:
%2 = atomicrmw volatile sub ptr subrspace(1) %0, i32 1
syncscope("agent") seq_cst
After:
%2 = atomicrmw volatile sub ptr subrspace(1) %0, i32 1
syncscope("agent") monotonic
* Also adds OpenCL 1.0 atom_* variants without volatile on the pointer.
They are added for backward compatibility.
f38cf01fc8