dp4a works

Author: masahi

python/tvm/tir/tensor_intrin/dot_product_common.py

@@ -45,10 +45,9 @@ def dp4a_impl(
         T.reads(C[0], A[0:4], B[0:4])
         T.writes(C[0])
 
-        A_i8x4 = B.vload([0], "int8x4")
-        B_i8x4 = B.vload([0], "int8x4")
-
-        C[0] = T.call_pure_extern("__dp4a", A_i8x4, B_i8x4, C[0], dtype="int32")
+        C[0] += T.call_pure_extern(
+            "__dp4a", A.vload([0], "int8x4"), B.vload([0], "int8x4"), T.int32(0), dtype="int32"
+        )
 
 
 DP4A_INTRIN = "dp4a"