!4972 fix post training quant

Merge pull request !4972 from xutianchun/quant_0822

mindspore/lite/tools/converter/quantizer/post_training_quantizer.cc

@@ -227,10 +227,10 @@ struct DivergInfo {
     int zero_point = 0;
     if (quant_min == 0 && quant_max == 255) {
       zero_point = 128;
-    } else if (quant_min == -128 && quant_max == 127) {
+    } else if (quant_min == -127 && quant_max == 127) {
       zero_point = 0;
     } else {
-      MS_LOG(ERROR) << "unexpectd quant range, quant_min: " << quant_min << " quant_max: " << quant_max;
+      MS_LOG(WARNING) << "unexpectd quant range, quant_min: " << quant_min << " quant_max: " << quant_max;
     }
     return std::make_pair(this->cnode, zero_point);
   }
@@ -486,7 +486,7 @@ PostTrainingQuantizer::PostTrainingQuantizer(FuncGraphPtr graph, string path, in
   this->target_type_ = target_type;
   if (target_type == kNumberTypeInt8) {
     quant_max = (1 << (this->bit_num - 1)) - 1;  // 127
-    quant_min = -(1 << (this->bit_num - 1));     // -128
+    quant_min = -quant_max;     // -127
   } else if (target_type == kNumberTypeUInt8) {
     quant_max = (1 << this->bit_num) - 1;  // 255
     quant_min = 0;

mindspore/lite/tools/converter/quantizer/quant_cast.cc

@@ -100,7 +100,7 @@ STATUS QuantCast::Run(FuncGraphPtr graph) {
         }
         std::vector<AnfNodePtr> op_inputs = {value_node, input_cnode};
         auto quant_cast_cnode = graph->NewCNode(op_inputs);
-        quant_cast_cnode->set_fullname_with_scope(cnode->fullname_with_scope() + "_quant_cast");
+        quant_cast_cnode->set_fullname_with_scope(cnode->fullname_with_scope() + "_quant_cast_" + std::to_string(i));
         cnode->set_input(i, quant_cast_cnode);
         MS_LOG(DEBUG) << "Add quant cast. "
                       << "cur_node: " << cnode->fullname_with_scope() << " quant_type: " << curnode_quant_type

mindspore/lite/tools/converter/quantizer/quantize_util.cc

@@ -220,11 +220,11 @@ STATUS CalQuantizationParams(schema::QuantParamT *quantParam, double mMin, doubl
                              bool narrowRange, int numBits) {
   MS_ASSERT(quantParam != nullptr);
   if (mMin > 0.0f) {
-    MS_LOG(ERROR) << "min " << mMin << " is bigger then 0, set to 0, this may course low precision";
+    MS_LOG(DEBUG) << "min " << mMin << " is bigger then 0, set to 0, this may course low precision";
     mMin = 0.0f;
   }
   if (mMax < 0.0f) {
-    MS_LOG(ERROR) << "mMax " << mMax << " is smaller than 0, set to 0, this may course low precision";
+    MS_LOG(DEBUG) << "mMax " << mMax << " is smaller than 0, set to 0, this may course low precision";
     mMax = 0.0f;
   }
   if (mMin > mMax) {