llvm

37a9a2a9 - [SYCL] Specialize atomic fetch_add for floating point types (#2765)

[SYCL] Specialize atomic fetch_add for floating point types (#2765) The new EXT/SPV_EXT_shader_atomic_float_add SPIR-V extension allows us to further specialize atomic::fetch_add() for floating point types. In device mode, we'll now be creating an external call to a built-in-like __spirv_AtomicFAddEXT(). This is similar to what is done for other atomic binary instructions, e.g. the integer specialization of fetch_add() being mapped onto __spirv_AtomicIAdd(). Furthermore, atomic::fetch_sub() is also re-implemented to use __spirv_AtomicFAddEXT(), the added operand being a negation of the original one. The new implementation can be exposed if a dedicated macro is defined: SYCL_USE_NATIVE_FP_ATOMICS. Otherwise, a fallback is used, where the atomic operation is done via spinlock emulation. At the moment of committing this, only Intel GPUs support the "native" implementation, which relies on a SPIR-V extension. Tests for the feature have been finalized in intel/llvm-test-suite#104. Signed-off-by: Artem Gindinson artem.gindinson@intel.com