vector benchmark

benchmarks/vector/saxpy/vx_vec_saxpy.s

@@ -0,0 +1,26 @@
+.type vx_vec_saxpy, @function
+.global vx_vec_saxpy
+# void
+# saxpy(size_t n, int factor, int *a, int *b)
+# {  for (int i=0; i<n; i++) { y[i] = a * x[i] + y[i];}  }
+#
+# register arguments:
+#     a0      n
+#     a1      factor
+#     a2      a
+#     a3      b
+vx_vec_saxpy:
+    vsetvli a4, a0, e32, m8
+loop:
+    vlw.v v0, (a2)
+    sub a0, a0, a4
+    slli a4, a4, 2
+    add a2, a2, a4
+    vlw.v v1, (a3)
+    vmul.vx v0, v0, a1
+    vadd.vv v1, v0, v1
+#   vmacc.vx v1, rs1, v0
+    vsw.v v1, (a3)
+    add a3, a3, a4
+    bnez a0, loop
+    ret