Address all Copilot review comments (round 3)

psiddh · psiddh · commit 91cd412e209f · 2026-06-16T16:23:54.000-07:00
- Make MFCC test_input arrays static const (flash, not RAM)
- Copy sizes/dim_order to local arrays instead of const_cast
- Fix comment: "double intermediate" not "inline assembly"
- Remove unused arena in HelloExecuTorch
- Remove cmsis_nn from export_model.py requirements (not imported)
- Update generate_test_input.py to emit static const arrays
diff --git a/examples/arduino/examples/HelloExecuTorch/HelloExecuTorch.ino b/examples/arduino/examples/HelloExecuTorch/HelloExecuTorch.ino
@@ -20,7 +20,6 @@ using executorch::runtime::MemoryAllocator;
 using executorch::runtime::Program;
 using executorch::runtime::Result;
 
-alignas(16) static uint8_t arena[32 * 1024];
 
 void setup() {
   Serial.begin(115200);
diff --git a/examples/arduino/examples/KeywordSpotting/KeywordSpotting.ino b/examples/arduino/examples/KeywordSpotting/KeywordSpotting.ino
@@ -103,11 +103,15 @@ void setup() {
   // Set input from MFCC data
   auto imeta = meta->input_tensor_meta(0);
   if (!imeta.ok()) { Serial.println("FAIL: imeta"); while (1) delay(1000); }
+  // Copy sizes/dim_order to local mutable arrays — TensorImpl takes
+  // mutable pointers but TensorInfo exposes const spans from the .pte.
+  int32_t input_sizes[4];
+  for (size_t d = 0; d < imeta->sizes().size(); d++) input_sizes[d] = imeta->sizes()[d];
+  uint8_t input_dim_order[4];
+  for (size_t d = 0; d < imeta->dim_order().size(); d++) input_dim_order[d] = imeta->dim_order()[d];
   executorch::aten::TensorImpl iimpl(
       imeta->scalar_type(), imeta->sizes().size(),
-      const_cast<executorch::aten::TensorImpl::SizesType*>(imeta->sizes().data()),
-      test_input,
-      const_cast<executorch::aten::TensorImpl::DimOrderType*>(imeta->dim_order().data()));
+      input_sizes, const_cast<float*>(test_input), input_dim_order);
   executorch::aten::Tensor it(&iimpl);
   Error serr = method->set_input(EValue(it), 0);
   if (serr != Error::Ok) {
diff --git a/examples/arduino/examples/KeywordSpotting/mfcc_down.h b/examples/arduino/examples/KeywordSpotting/mfcc_down.h
@@ -2,7 +2,7 @@
 // 49 time frames x 10 MFCC coefficients = 490 float values
 #pragma once
 
-static float test_input[490] = {
+static const float test_input[490] = {
     -507.322296f, 19.031570f,  11.984641f,  4.382929f,   2.187682f,
     -2.236901f,   -5.487720f,  -4.277254f,  -3.514820f,  -2.503060f,
     -506.204712f, 16.616709f,  9.791165f,   1.699199f,   0.929732f,
diff --git a/examples/arduino/examples/KeywordSpotting/mfcc_go.h b/examples/arduino/examples/KeywordSpotting/mfcc_go.h
@@ -2,7 +2,7 @@
 // 49 time frames x 10 MFCC coefficients = 490 float values
 #pragma once
 
-static float test_input[490] = {
+static const float test_input[490] = {
     -258.684387f, 58.165886f,  3.168766f,   7.946958f,   3.306427f,
     9.479866f,    5.606411f,   3.052066f,   -7.099144f,  -2.936588f,
     -265.543152f, 59.884911f,  7.261999f,   10.668991f,  5.931267f,
diff --git a/examples/arduino/examples/KeywordSpotting/mfcc_left.h b/examples/arduino/examples/KeywordSpotting/mfcc_left.h
@@ -2,7 +2,7 @@
 // 49 time frames x 10 MFCC coefficients = 490 float values
 #pragma once
 
-static float test_input[490] = {
+static const float test_input[490] = {
     -506.012085f, 19.527250f,  16.936848f,  10.008033f,  5.769112f,
     2.787449f,    -1.006611f,  -2.850882f,  -6.202645f,  -7.454649f,
     -507.090790f, 17.847679f,  13.063059f,  4.104880f,   0.178153f,
diff --git a/examples/arduino/examples/KeywordSpotting/mfcc_no.h b/examples/arduino/examples/KeywordSpotting/mfcc_no.h
@@ -2,7 +2,7 @@
 // 49 time frames x 10 MFCC coefficients = 490 float values
 #pragma once
 
-static float test_input[490] = {
+static const float test_input[490] = {
     -503.800079f, 18.831722f,  14.820873f,  5.787148f,   0.999313f,
     0.268913f,    -0.730756f,  -3.137853f,  -7.256411f,  -5.541068f,
     -504.038208f, 16.911341f,  7.856658f,   4.925719f,   2.151710f,
diff --git a/examples/arduino/examples/KeywordSpotting/mfcc_off.h b/examples/arduino/examples/KeywordSpotting/mfcc_off.h
@@ -2,7 +2,7 @@
 // 49 time frames x 10 MFCC coefficients = 490 float values
 #pragma once
 
-static float test_input[490] = {
+static const float test_input[490] = {
     -175.550064f, 36.675400f, 1.704316f,   19.794855f,  6.347660f,
     5.608477f,    -0.642213f, 12.882412f,  10.317157f,  1.862832f,
     -170.788635f, 46.692368f, 3.367630f,   18.206554f,  4.198709f,
diff --git a/examples/arduino/examples/KeywordSpotting/mfcc_on.h b/examples/arduino/examples/KeywordSpotting/mfcc_on.h
@@ -2,7 +2,7 @@
 // 49 time frames x 10 MFCC coefficients = 490 float values
 #pragma once
 
-static float test_input[490] = {
+static const float test_input[490] = {
     -169.743530f, 21.981453f,  11.185447f,  14.363379f,  7.026345f,
     8.041018f,    2.363853f,   10.931651f,  1.520875f,   0.555498f,
     -170.588623f, 23.007666f,  8.181622f,   8.672327f,   4.949448f,
diff --git a/examples/arduino/examples/KeywordSpotting/mfcc_right.h b/examples/arduino/examples/KeywordSpotting/mfcc_right.h
@@ -2,7 +2,7 @@
 // 49 time frames x 10 MFCC coefficients = 490 float values
 #pragma once
 
-static float test_input[490] = {
+static const float test_input[490] = {
     -476.811279f, -5.110255f,  17.742918f,  12.991923f,  -10.009543f,
     16.099197f,   -8.517653f,  -1.396785f,  -3.775454f,  -5.338952f,
     -485.660583f, 5.495706f,   14.872177f,  5.643840f,   -11.644445f,
diff --git a/examples/arduino/examples/KeywordSpotting/mfcc_stop.h b/examples/arduino/examples/KeywordSpotting/mfcc_stop.h
@@ -2,7 +2,7 @@
 // 49 time frames x 10 MFCC coefficients = 490 float values
 #pragma once
 
-static float test_input[490] = {
+static const float test_input[490] = {
     -247.903046f, 55.235271f,  10.757340f,  6.266783f,   2.433547f,
     10.195817f,   7.269604f,   12.213093f,  -0.981211f,  1.087342f,
     -238.716736f, 62.930332f,  18.089561f,  13.942317f,  5.814198f,
diff --git a/examples/arduino/examples/KeywordSpotting/mfcc_up.h b/examples/arduino/examples/KeywordSpotting/mfcc_up.h
@@ -2,7 +2,7 @@
 // 49 time frames x 10 MFCC coefficients = 490 float values
 #pragma once
 
-static float test_input[490] = {
+static const float test_input[490] = {
     -485.746887f, -1.299434f,  -3.842550f,  -3.186123f,  -0.103117f,
     2.111575f,    -2.739380f,  2.771092f,   -3.467221f,  -0.501581f,
     -476.447784f, 7.004504f,   1.368172f,   0.103827f,   -1.262842f,
diff --git a/examples/arduino/examples/KeywordSpotting/mfcc_yes.h b/examples/arduino/examples/KeywordSpotting/mfcc_yes.h
@@ -2,7 +2,7 @@
 // 49 time frames x 10 MFCC coefficients = 490 float values
 #pragma once
 
-static float test_input[490] = {
+static const float test_input[490] = {
     -234.681412f, 43.233639f,  5.400801f,   20.397280f,  2.792400f,
     -1.854441f,   0.334868f,   19.084484f,  0.550039f,   8.545486f,
     -228.795731f, 48.089474f,  16.147015f,  16.006577f,  4.168744f,
diff --git a/examples/arduino/export_model.py b/examples/arduino/export_model.py
@@ -15,7 +15,7 @@
     python export_model.py --checkpoint my_weights.pth --output model.h
 
 Requirements:
-    pip install executorch soundfile numpy torch torchao cmsis_nn
+    pip install executorch soundfile numpy torch torchao
 """
 
 import argparse
diff --git a/examples/arduino/generate_test_input.py b/examples/arduino/generate_test_input.py
@@ -99,7 +99,7 @@ def main():
     h = f"// MFCC from: {args.input}\n"
     h += "// 49 time frames x 10 MFCC coefficients = 490 float values\n"
     h += "#pragma once\n\n"
-    h += "static float test_input[490] = {\n"
+    h += "static const float test_input[490] = {\n"
     for i in range(0, len(mfcc), 8):
         h += "    " + ",".join(f"{v:.6f}f" for v in mfcc[i : i + 8]) + ",\n"
     h += "};\n"
diff --git a/examples/arduino/platform_stubs.c b/examples/arduino/platform_stubs.c
@@ -25,7 +25,7 @@ __attribute__((weak)) int fprintf(FILE* stream, const char* fmt, ...) {
 }
 
 #if defined(__ARM_EABI__)
-// Use inline assembly to avoid the compiler lowering (long long)f back
+// Use double intermediate to avoid the compiler lowering (long long)f back
 // into a call to __aeabi_f2lz, which would cause infinite recursion.
 __attribute__((weak)) long long __aeabi_f2lz(float f) {
     long long result;
