workaround clang crash for gfx908

(gfx908 only) workaround for compiler crash in fused kernels on mainline #9110; #10738 seems ok
error message was "fatal error: error in backend: Error while trying to spill VGPR0 from class
VGPR_32: Cannot scavenge register without an emergency spill slot!"
this fall back to less ideal way of handle NPadding in fused attention kernel

include/ck/ck.hpp

@@ -144,6 +144,17 @@
 // workaround: compiler gnerating inefficient ds_write instructions
 #define CK_WORKAROUND_SWDEV_XXXXXX_INT8_DS_WRITE_ISSUE 1
 
+// (gfx908 only) workaround: compiler crash in fused kernels on mainline #9110; #10738 seems ok
+// error message was "fatal error: error in backend: Error while trying to spill VGPR0 from class
+// VGPR_32: Cannot scavenge register without an emergency spill slot!"
+// this fall back to less ideal way of handle NPadding in fused attention kernel
+#ifdef __gfx908__
+#define CK_WORKAROUND_SWDEV_XXXXXX_ATTN_KERNEL_CLANG_CANNOT_SCAVENGE_REGISTER 1
+#else
+// for __gfx90a__, ...
+#define CK_WORKAROUND_SWDEV_XXXXXX_ATTN_KERNEL_CLANG_CANNOT_SCAVENGE_REGISTER 0
+#endif // __gfx908__
+
 // workaround: verifaction failure, due to compiler regression, for conv bwd-data fp16 using some
 // tuning parameter
 #define CK_WORKAROUND_SWDEV_325164 0

include/ck/tensor_operation/gpu/block/blockwise_softmax.hpp

@@ -16,7 +16,8 @@ template <index_t BlockSize,
           typename AccDataType,
           typename ThreadMap_M_K, // thread_id to m_k
           typename ThreadClusterDesc_M_K,
-          typename ThreadSliceDesc_M_K>
+          typename ThreadSliceDesc_M_K,
+          bool IgnoreNaN = false>
 struct BlockwiseSoftmax
 {
     static constexpr auto I0         = Number<0>{};
@@ -27,11 +28,33 @@ struct BlockwiseSoftmax
     using ThreadSliceDesc_M = decltype(
         make_naive_tensor_descriptor_packed(make_tuple(ThreadSliceDesc_M_K{}.GetLength(I0))));
 
-    using ThreadwiseMaxReduce = ThreadwiseReduction<AccDataType,
+    using ThreadwiseMaxReduce = typename conditional<
+        IgnoreNaN,
+        ThreadwiseReduction<AccDataType,
                             ThreadSliceDesc_M_K,
                             ThreadSliceDesc_M,
                             reduce::Max,
-                                                    false>;
+                            false,
+                            detail::AccumulateWithNanIgnore<reduce::Max, AccDataType>>,
+        ThreadwiseReduction<AccDataType,
+                            ThreadSliceDesc_M_K,
+                            ThreadSliceDesc_M,
+                            reduce::Max,
+                            false>>::type;
+
+    using ThreadwiseSumReduce = typename conditional<
+        IgnoreNaN,
+        ThreadwiseReduction<AccDataType,
+                            ThreadSliceDesc_M_K,
+                            ThreadSliceDesc_M,
+                            reduce::Add,
+                            false,
+                            detail::AccumulateWithNanIgnore<reduce::Add, AccDataType>>,
+        ThreadwiseReduction<AccDataType,
+                            ThreadSliceDesc_M_K,
+                            ThreadSliceDesc_M,
+                            reduce::Add,
+                            false>>::type;
 
     using ThreadClusterLengths_M_K = decltype(ThreadClusterDesc_M_K{}.GetLengths());
 
@@ -49,12 +72,6 @@ struct BlockwiseSoftmax
                                                                 reduce::Add,
                                                                 false>;
 
-    using ThreadwiseSumReduce = ThreadwiseReduction<AccDataType,
-                                                    ThreadSliceDesc_M_K,
-                                                    ThreadSliceDesc_M,
-                                                    reduce::Add,
-                                                    false>;
-
     using BufferType = StaticBuffer<AddressSpaceEnum::Vgpr, AccDataType, MRepeat, true>;
 
     template <typename CThreadBuffer, typename WorkspaceBuffer>
@@ -74,7 +91,9 @@ struct BlockwiseSoftmax
         static_for<0, MRepeat, 1>{}([&](auto iM) {
             static_for<0, KRepeat, 1>{}([&](auto iK) {
                 auto offset = Number<ThreadSliceDesc_M_K{}.CalculateOffset(make_tuple(iM, iK))>{};
-                in_thread_buf(offset) = math::exp(in_thread_buf[offset] - max_value_buf(iM));
+                in_thread_buf(offset) = IgnoreNaN && ck::math::isnan(in_thread_buf[offset])
+                                            ? 0
+                                            : math::exp(in_thread_buf[offset] - max_value_buf(iM));
             });
         });
 

include/ck/tensor_operation/gpu/grid/gridwise_batched_gemm_softmax_gemm_xdl_cshuffle_v1.hpp

@@ -717,7 +717,12 @@ struct GridwiseBatchedGemmSoftmaxGemm_Xdl_CShuffle
                                                   FloatGemmAcc,
                                                   decltype(threadid_to_m_n_thread_cluster_adaptor),
                                                   decltype(thread_cluster_desc_m_n),
-                                                  decltype(thread_slice_desc_m_n)>{};
+                                                  decltype(thread_slice_desc_m_n)
+#if CK_WORKAROUND_SWDEV_XXXXXX_ATTN_KERNEL_CLANG_CANNOT_SCAVENGE_REGISTER
+                                                      ,
+                                                  true
+#endif
+                                                  >{};
 
         const index_t num_gemm1_k_block_outer_loop =
             b_grid_desc_bk0_n_bk1.GetLength(I1) / NPerBlock;
@@ -758,10 +763,15 @@ struct GridwiseBatchedGemmSoftmaxGemm_Xdl_CShuffle
                                                                    num_k_block_main_loop);
 
             // Acc0 elementwise Op
+#if CK_WORKAROUND_SWDEV_XXXXXX_ATTN_KERNEL_CLANG_CANNOT_SCAVENGE_REGISTER
+            static_for<0, acc_thread_buf.Size(), 1>{}(
+                [&](auto i) { acc_element_op(acc_thread_buf(i), acc_thread_buf[i]); });
+#else
             static_for<0, acc_thread_buf.Size(), 1>{}([&](auto i) {
                 ElementOpPredicatedResetNaNToMinusInf<PadN>{}.Run(
                     acc_thread_buf(i), acc_element_op, acc_thread_buf[i]);
             });
+#endif
 
             block_sync_lds(); // wait for lds read in gemm0 blockwise gemm