diff --git a/lib/codegen/selection/generator.cc b/lib/codegen/selection/generator.cc
index 63f72f9ff..6507080f9 100644
--- a/lib/codegen/selection/generator.cc
+++ b/lib/codegen/selection/generator.cc
@@ -903,9 +903,9 @@ void generator::visit_atomic_add_inst(ir::atomic_add_inst* add) {
       std::string suffix = vec == 2 ? "x2" : "";
       std::string mod = nbits == 32 ? "" : ".noftz";
       std::string ty_str = add->get_type()->get_scalar_ty()->is_floating_point_ty() ? "f" : "u";
-      std::string asm_str = "@$0 atom.global.gpu.add" + mod + "." + ty_str + std::to_string(nbits) + suffix + " $1, [$2" + offset + "], $3;";
+      std::string asm_str = "@$1 atom.global.gpu.add" + mod + "." + ty_str + std::to_string(nbits) + suffix + " $0, [$2" + offset + "], $3;";
       std::string ty_id = nbits == 32 ? ty_str : (vec == 1 ? "h" : "r");
-      std::string constraint = "b,=" + ty_id + ",l," + ty_id;
+      std::string constraint = "=" + ty_id + ",b,l," + ty_id;
       // create inline asm
       InlineAsm *iasm = InlineAsm::get(fn_ty, asm_str, constraint, true);
       // call asm
@@ -922,9 +922,9 @@ void generator::visit_atomic_add_inst(ir::atomic_add_inst* add) {
     FunctionType *fn_ty = FunctionType::get(ty, arg_ty, false);
     std::string mod = nbits == 32 ? "" : ".noftz";
     std::string ty_str = add->get_type()->get_scalar_ty()->is_floating_point_ty() ? "f" : "u";
-    std::string asm_str = "@$0 atom.global.gpu.add" + mod + "." + ty_str + std::to_string(nbits) + " $1, [$2], $3;";
+    std::string asm_str = "@$1 atom.global.gpu.add" + mod + "." + ty_str + std::to_string(nbits) + " $0, [$2], $3;";
     std::string ty_id = nbits == 32 ? "r" : "h";
-    InlineAsm *iasm = InlineAsm::get(fn_ty, asm_str, "b,="+ty_id+",l,"+ty_id, true);
+    InlineAsm *iasm = InlineAsm::get(fn_ty, asm_str, "="+ty_id+",b,l,"+ty_id, true);
 
     BasicBlock *current = builder_->GetInsertBlock();
     Module *module = current->getModule();
diff --git a/lib/codegen/transform/prefetch.cc b/lib/codegen/transform/prefetch.cc
index 876ee3e43..96bcf57d7 100644
--- a/lib/codegen/transform/prefetch.cc
+++ b/lib/codegen/transform/prefetch.cc
@@ -95,11 +95,17 @@ void prefetch::run(ir::module &mod) {
       });
 
       builder.set_insert_point(bb->get_first_non_phi());
-      for (ir::instruction *i : loads) {
+      auto& inst_list = bb->get_inst_list();
+      for (ir::instruction *i : loads){
+        auto it = std::find(inst_list.begin(), inst_list.end(), i);
+        // make sure we don't invalidate insert point
+        // in case instruction already at the top
+        if(it == builder.get_insert_point())
+          continue;
         bb->erase(i);
         builder.insert(i);
       }
     }
   }
 }
-} // namespace triton::codegen::transform
\ No newline at end of file
+} // namespace triton::codegen::transform