add conv_direct_int8 impl

paddle/fluid/lite/arm/math/CMakeLists.txt

@@ -37,6 +37,8 @@ cc_library(math_arm SRCS
     dropout.cc
     gemm_prepacked_int8.cc
     gemv_arm_int8.cc
+    conv3x3s1_direct_int8.cc
+    conv3x3s2_direct_int8.cc
     DEPS ${lite_kernel_deps} eigen3 framework_proto_lite)
   # TODO(TJ): fix me do not deps proto
  

paddle/fluid/lite/kernels/arm/conv_compute.cc

@@ -127,7 +127,7 @@ void ConvComputeInt8<Ptype_out>::PrepareForRun() {
     VLOG(3) << "DepthwiseConv Int8";
   } else if (param.groups == 1 && kw == 3 && (sw == 1 || sw == 2) &&
              kps_equal && no_dilation) {
-    // impl_ = new lite::arm::math::DirectConv<Ptype_out>;
+    impl_ = new lite::arm::math::DirectConvInt8<Ptype_out>;
   } else {
     VLOG(3) << "GemmLikeConvInt8";
     impl_ = new lite::arm::math::GemmLikeConvInt8<Ptype_out>;