Add a flag to force CPU inference in the inference calculator

PiperOrigin-RevId: 678131539

mediapipe/calculators/tensor/BUILD

@@ -408,6 +408,14 @@ mediapipe_proto_library(
     ],
 )
 
+config_setting(
+    name = "force_cpu_inference",
+    values = {
+        "define": "MEDIAPIPE_FORCE_CPU_INFERENCE=true",
+    },
+    visibility = ["//visibility:public"],
+)
+
 # This target defines the "InferenceCalculator" component, which looks for the available concrete
 # implementations linked into the current binary and picks the one to use.
 # You can depend on :inference_calculator instead if you want to automatically include a default
@@ -420,6 +428,10 @@ cc_library_with_tflite(
     name = "inference_calculator_interface",
     srcs = ["inference_calculator.cc"],
     hdrs = ["inference_calculator.h"],
+    local_defines = select({
+        ":force_cpu_inference": ["MEDIAPIPE_FORCE_CPU_INFERENCE=1"],
+        "//conditions:default": [],
+    }),
     tflite_deps = [
         ":inference_runner",
         ":inference_io_mapper",

mediapipe/calculators/tensor/inference_calculator.cc

@@ -50,6 +50,8 @@ class InferenceCalculatorSelectorImpl
             subgraph_node);
     std::vector<absl::string_view> impls;
 
+#if !defined(MEDIAPIPE_FORCE_CPU_INFERENCE) || !MEDIAPIPE_FORCE_CPU_INFERENCE
+
     const bool should_use_gpu =
         !options.has_delegate() ||  // Use GPU delegate if not specified
         (options.has_delegate() && options.delegate().has_gpu());
@@ -59,7 +61,6 @@ class InferenceCalculatorSelectorImpl
 #if MEDIAPIPE_METAL_ENABLED
       impls.emplace_back("Metal");
 #endif
-
       const bool prefer_gl_advanced =
           options.delegate().gpu().use_advanced_gpu_api() &&
           (api == Gpu::ANY || api == Gpu::OPENGL || api == Gpu::OPENCL);
@@ -71,6 +72,8 @@ class InferenceCalculatorSelectorImpl
         impls.emplace_back("GlAdvanced");
       }
     }
+#endif  // !defined(MEDIAPIPE_FORCE_CPU_INFERENCE) ||
+        // !MEDIAPIPE_FORCE_CPU_INFERENCE
     impls.emplace_back("Cpu");
     impls.emplace_back("Xnnpack");
     for (const auto& suffix : impls) {