Add arm int8 place automatic, test=develop (#3234)

lite/api/cxx_api.cc

@@ -294,6 +294,32 @@ void Predictor::Build(const cpp::ProgramDesc &desc,
   inner_places.emplace_back(TARGET(kHost), PRECISION(kAny), DATALAYOUT(kAny));
   inner_places.emplace_back(
       TARGET(kHost), PRECISION(kFloat), DATALAYOUT(kNCHW));
+
+  const std::vector<std::string> quant_dequant_op = {
+      "fake_quantize_abs_max",
+      "fake_quantize_range_abs_max",
+      "fake_quantize_moving_average_abs_max",
+      "fake_quantize_dequantize_moving_average_abs_max",
+      "fake_dequantize_max_abs",
+      "fake_channel_wise_dequantize_max_abs"};
+  bool is_quantized_model = false;
+  for (size_t i = 0; i < program_desc_.BlocksSize() && !is_quantized_model;
+       ++i) {
+    auto *block_desc = program_desc_.GetBlock<cpp::BlockDesc>(i);
+    for (size_t j = 0; j < block_desc->OpsSize() && !is_quantized_model; ++j) {
+      auto *op_desc = block_desc->GetOp<cpp::OpDesc>(j);
+      std::string op_type = op_desc->Type();
+      if (std::find(quant_dequant_op.begin(),
+                    quant_dequant_op.end(),
+                    op_type) != quant_dequant_op.end()) {
+        is_quantized_model = true;
+      }
+    }
+  }
+  if (is_quantized_model) {
+    inner_places.emplace_back(Place{TARGET(kARM), PRECISION(kInt8)});
+  }
+
   Program program(desc, scope_, inner_places);
 
   core::KernelPickFactor factor;

lite/api/opt.cc

@@ -67,7 +67,6 @@ DEFINE_string(valid_targets,
               "arm",
               "The targets this model optimized for, should be one of (arm, "
               "opencl, x86), splitted by space");
-DEFINE_bool(prefer_int8_kernel, false, "Prefer to run model with int8 kernels");
 DEFINE_bool(print_supported_ops,
             false,
             "Print supported operators on the inputed target");
@@ -121,11 +120,6 @@ std::vector<Place> ParserValidPlaces() {
       << "At least one target should be set, should set the "
          "command argument 'valid_targets'";
 
-  if (FLAGS_prefer_int8_kernel) {
-    LOG(WARNING) << "Int8 mode is only support by ARM target";
-    valid_places.insert(valid_places.begin(),
-                        Place{TARGET(kARM), PRECISION(kInt8)});
-  }
   return valid_places;
 }
 
@@ -255,7 +249,6 @@ void PrintHelpInfo() {
       "        `--optimize_out_type=(protobuf|naive_buffer)`\n"
       "        `--optimize_out=<output_optimize_model_dir>`\n"
       "        `--valid_targets=(arm|opencl|x86|npu|xpu)`\n"
-      "        `--prefer_int8_kernel=(true|false)`\n"
       "        `--record_tailoring_info=(true|false)`\n"
       "  Arguments of model checking and ops information:\n"
       "        `--print_all_ops=true`   Display all the valid operators of "