Patch fp16 to fix Xcode 16 builds with XNNPACK EP targeting x86_64.

.github/workflows/mac.yml

@@ -19,7 +19,7 @@ env:
   python_version: 3.11
 
 jobs:
-  ARM64:
+  ARM64-Xcode16:
     runs-on: macos-14
 
     env:
@@ -60,6 +60,54 @@ jobs:
           --use_xnnpack \
           --use_binskim_compliant_compile_flags
 
+  ARM64-Xcode16-targeting-iphonesimulator-x86_64:
+    runs-on: macos-14
+
+    env:
+      xcode_version: 16
+
+    timeout-minutes: 60
+
+    steps:
+    - uses: actions/setup-python@v5
+      with:
+        python-version: ${{ env.python_version }}
+
+    - name: Verify ARM64 machine
+      shell: python
+      run: |
+        import platform
+        assert platform.machine() == "arm64", "This job expects to be run on an ARM64 machine."
+
+    - name: Use Xcode ${{ env.xcode_version }}
+      shell: bash
+      run: |
+        XCODE_DEVELOPER_DIR="/Applications/Xcode_${{ env.xcode_version }}.app/Contents/Developer"
+        sudo xcode-select --switch "${XCODE_DEVELOPER_DIR}"
+
+    - uses: actions/checkout@v4
+
+    # Note: Setting onnxruntime_BUILD_UNIT_TESTS=OFF as a workaround for
+    # https://github.com/microsoft/onnxruntime/issues/22245.
+    - name: Build
+      shell: bash
+      run: |
+        python ./tools/ci_build/build.py \
+          --build_dir ./build \
+          --update \
+          --build --parallel \
+          --skip_tests \
+          --build_apple_framework \
+          --use_xcode \
+          --use_coreml \
+          --use_xnnpack \
+          --use_binskim_compliant_compile_flags \
+          --ios \
+          --apple_deploy_target=13.0 \
+          --apple_sysroot=iphonesimulator \
+          --osx_arch=x86_64 \
+          --cmake_extra_defines=onnxruntime_BUILD_UNIT_TESTS=OFF
+
   Vcpkg:
     runs-on: macos-13
     steps:

cmake/external/xnnpack.cmake

@@ -21,7 +21,38 @@ endif()
 FetchContent_Declare(psimd URL ${DEP_URL_psimd} URL_HASH SHA1=${DEP_SHA1_psimd})
 onnxruntime_fetchcontent_makeavailable(psimd)
 set(PSIMD_SOURCE_DIR ${psimd_SOURCE_DIR})
-FetchContent_Declare(fp16 URL ${DEP_URL_fp16} URL_HASH SHA1=${DEP_SHA1_fp16})
+
+block(PROPAGATE fp16_PATCH_COMMAND)
+  # only apply fp16 patch for Apple x86_64 targets
+
+  if(APPLE)
+    if(NOT "${CMAKE_OSX_ARCHITECTURES}" STREQUAL "")
+      if ("x86_64" IN_LIST CMAKE_OSX_ARCHITECTURES)
+        set(fp16_PATCH_REQUIRED 1)
+      endif()
+    else()
+      # CMAKE_OSX_ARCHITECTURES unspecified, check host
+      if(CMAKE_SYSTEM_PROCESSOR STREQUAL "x86_64")
+        set(fp16_PATCH_REQUIRED 1)
+      endif()
+    endif()
+  endif()
+
+  if(fp16_PATCH_REQUIRED)
+    message(STATUS "Applying fp16 patch.")
+    set(fp16_PATCH_FILE ${PROJECT_SOURCE_DIR}/patches/fp16/remove_math_h_dependency_from_fp16_h.patch)
+    set(fp16_PATCH_COMMAND ${Patch_EXECUTABLE} --binary --ignore-whitespace -p1 < ${fp16_PATCH_FILE})
+  else()
+    set(fp16_PATCH_COMMAND "")
+  endif()
+endblock()
+
+FetchContent_Declare(
+    fp16
+    URL ${DEP_URL_fp16}
+    URL_HASH SHA1=${DEP_SHA1_fp16}
+    PATCH_COMMAND ${fp16_PATCH_COMMAND}
+    )
 onnxruntime_fetchcontent_makeavailable(fp16)
 
 # pthreadpool depends on fxdiv

cmake/patches/fp16/readme.md

@@ -0,0 +1,11 @@
+# remove_math_h_dependency_from_fp16_h.patch
+
+Remove dependency on math.h (with fabsf()) to work around Xcode 16 build error for iphonesimulator x86_64 target:
+
+/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk/usr/include/math.h:614:27: error:
+      _Float16 is not supported on this target
+  614 | extern _Float16 __fabsf16(_Float16) __API_AVAILABLE(macos(15.0), ios(18.0), watchos(11.0), tvos(18.0));
+      |
+
+This patch was adapted from this PR: https://github.com/Maratyszcza/FP16/pull/32
+See also: https://github.com/google/XNNPACK/issues/6989

cmake/patches/fp16/remove_math_h_dependency_from_fp16_h.patch

@@ -0,0 +1,29 @@
+diff --git a/include/fp16/fp16.h b/include/fp16/fp16.h
+index 2b61fff..1947805 100644
+--- a/include/fp16/fp16.h
++++ b/include/fp16/fp16.h
+@@ -4,10 +4,8 @@
+
+ #if defined(__cplusplus) && (__cplusplus >= 201103L)
+ 	#include <cstdint>
+-	#include <cmath>
+ #elif !defined(__OPENCL_VERSION__)
+ 	#include <stdint.h>
+-	#include <math.h>
+ #endif
+
+ #ifdef _MSC_VER
+@@ -228,9 +226,11 @@ static inline uint16_t fp16_ieee_from_fp32_value(float f) {
+ 	const float scale_to_inf = fp32_from_bits(UINT32_C(0x77800000));
+ 	const float scale_to_zero = fp32_from_bits(UINT32_C(0x08800000));
+ #endif
+-	float base = (fabsf(f) * scale_to_inf) * scale_to_zero;
+-
+ 	const uint32_t w = fp32_to_bits(f);
++	const float abs_f = fp32_from_bits(w & UINT32_C(0x7FFFFFFF));
++
++	float base = (abs_f * scale_to_inf) * scale_to_zero;
++
+ 	const uint32_t shl1_w = w + w;
+ 	const uint32_t sign = w & UINT32_C(0x80000000);
+ 	uint32_t bias = shl1_w & UINT32_C(0xFF000000);