Update on "Reuse GELU implementation from PyTorch core"

kernels/optimized doesn't need to support embedded systems, so it can just take a header-only dep on PyTorch.

Note that, because we will pick up Sleef internally and ignore it
externally thanks to ATen vec, this PR gets to enable optimized GELU in OSS.

Testing: CI to make sure this doesn't break mobile build modes; happy to take advice on anything not currently covered that might break.

Differential Revision: [D66335522](https://our.internmc.facebook.com/intern/diff/D66335522/)

[ghstack-poisoned]

Author: swolchok

build/build_apple_frameworks.sh

@@ -187,7 +187,6 @@ echo "Exporting headers"
 
 mkdir -p "$HEADERS_PATH"
 
-# Set BUCK2 to the path of the buck2 executable in $OUTPUT/*/buck2-bin/buck2-*
 BUCK2=$(find $SOURCE_ROOT_DIR -type f -path '*/buck2-bin/buck2-*' | head -n 1)
 if [[ -z "$BUCK2" ]]; then
   echo "Could not find buck2 executable in any buck2-bin directory under $OUTPUT"
@@ -208,11 +207,11 @@ check_command "$BUCK2"
 # So, just patch our generated framework to do that.
 sed -i '' '1i\
 #define C10_USING_CUSTOM_GENERATED_MACROS
-' $SOURCE_ROOT_DIR/runtime/core/portable_type/c10/macros/Macros.h
+' $HEADERS_PATH/executorch/runtime/core/portable_type/c10/macros/Macros.h
 sed -i '' '1i\
 #define C10_USING_CUSTOM_GENERATED_MACROS
-' $SOURCE_ROOT_DIR/runtime/core/portable_type/c10/macros/Export.h
-cp -r $SOURCE_ROOT_DIR/runtime/core/portable_type/c10 "$HEADERS_PATH/"
+' $HEADERS_PATH/executorch/runtime/core/portable_type/c10/macros/Export.h
+ln -s $HEADERS_PATH/executorch/runtime/core/portable_type/c10 "$HEADERS_PATH/"
 
 
 cp "$SOURCE_ROOT_DIR/extension/apple/ExecuTorch/Exported/"*.h "$HEADERS_PATH/executorch"

runtime/core/portable_type/c10/util/BFloat16-math.h

@@ -8,8 +8,7 @@ C10_CLANG_DIAGNOSTIC_PUSH()
 C10_CLANG_DIAGNOSTIC_IGNORE("-Wimplicit-float-conversion")
 #endif
 
-namespace std {
-
+namespace c10 {
 template <typename T>
 struct is_reduced_floating_point
     : std::integral_constant<
@@ -19,193 +18,201 @@ struct is_reduced_floating_point
 template <typename T>
 constexpr bool is_reduced_floating_point_v =
     is_reduced_floating_point<T>::value;
+} // namespace c10
+
+namespace std {
+
+#if !defined(FBCODE_CAFFE2) && !defined(C10_NODEPRECATED)
+using c10::is_reduced_floating_point;
+using c10::is_reduced_floating_point_v;
+#endif // !defined(FBCODE_CAFFE2) && !defined(C10_NODEPRECATED)
 
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T acos(T a) {
   return std::acos(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T asin(T a) {
   return std::asin(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T atan(T a) {
   return std::atan(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T atanh(T a) {
   return std::atanh(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T erf(T a) {
   return std::erf(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T erfc(T a) {
   return std::erfc(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T exp(T a) {
   return std::exp(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T expm1(T a) {
   return std::expm1(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline bool isfinite(T a) {
   return std::isfinite(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T log(T a) {
   return std::log(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T log10(T a) {
   return std::log10(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T log1p(T a) {
   return std::log1p(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T log2(T a) {
   return std::log2(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T ceil(T a) {
   return std::ceil(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T cos(T a) {
   return std::cos(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T floor(T a) {
   return std::floor(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T nearbyint(T a) {
   return std::nearbyint(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T sin(T a) {
   return std::sin(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T tan(T a) {
   return std::tan(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T sinh(T a) {
   return std::sinh(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T cosh(T a) {
   return std::cosh(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T tanh(T a) {
   return std::tanh(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T trunc(T a) {
   return std::trunc(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T lgamma(T a) {
   return std::lgamma(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T sqrt(T a) {
   return std::sqrt(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T rsqrt(T a) {
   return 1.0 / std::sqrt(float(a));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T abs(T a) {
   return std::abs(float(a));
 }
 #if defined(_MSC_VER) && defined(__CUDACC__)
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T pow(T a, double b) {
   return std::pow(float(a), float(b));
 }
 #else
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T pow(T a, double b) {
   return std::pow(float(a), b);
 }
 #endif
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T pow(T a, T b) {
   return std::pow(float(a), float(b));
 }
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 inline T fmod(T a, T b) {
   return std::fmod(float(a), float(b));
 }
@@ -238,7 +245,7 @@ inline T fmod(T a, T b) {
  */
 template <
     typename T,
-    typename std::enable_if_t<is_reduced_floating_point_v<T>, int> = 0>
+    typename std::enable_if_t<c10::is_reduced_floating_point_v<T>, int> = 0>
 C10_HOST_DEVICE inline T nextafter(T from, T to) {
   // Reference:
   // https://git.musl-libc.org/cgit/musl/tree/src/math/nextafter.c