[AArch64] Enable feature detection on Windows and Apple Silicon

Using the platform-specific functions IsProcessorFeaturePresent and
sysctlbyname to check individual features.

Bug: libyuv:980
Change-Id: I7971238ca72e5df862c30c2e65331c46dc634074
Reviewed-on: https://chromium-review.googlesource.com/c/libyuv/libyuv/+/5465591
Reviewed-by: Frank Barchard <fbarchard@chromium.org>
Commit-Queue: Frank Barchard <fbarchard@chromium.org>

include/libyuv/cpu_id.h

@@ -92,6 +92,7 @@ int MipsCpuCaps(const char* cpuinfo_name);
 LIBYUV_API
 int RiscvCpuCaps(const char* cpuinfo_name);
 
+#ifdef __aarch64__
 #if __linux__
 // On Linux, parse AArch64 features from getauxval(AT_HWCAP{,2}).
 LIBYUV_API
@@ -100,6 +101,7 @@ int AArch64CpuCaps(unsigned long hwcap, unsigned long hwcap2);
 LIBYUV_API
 int AArch64CpuCaps();
 #endif
+#endif
 
 // For testing, allow CPU flags to be disabled.
 // ie MaskCpuFlags(~kCpuHasSSSE3) to disable SSSE3.

source/cpu_id.cc

@@ -23,10 +23,22 @@
 #include <stdio.h>  // For fopen()
 #include <string.h>
 
-#ifdef __linux__
+#if defined(__linux__) && defined(__aarch64__)
 #include <sys/auxv.h>  // For getauxval()
 #endif
 
+#if defined(_WIN32) && defined(__aarch64__)
+#undef WIN32_LEAN_AND_MEAN
+#define WIN32_LEAN_AND_MEAN
+#undef WIN32_EXTRA_LEAN
+#define WIN32_EXTRA_LEAN
+#include <windows.h>  // For IsProcessorFeaturePresent()
+#endif
+
+#if defined(__APPLE__) && defined(__aarch64__)
+#include <sys/sysctl.h>  // For sysctlbyname()
+#endif
+
 #ifdef __cplusplus
 namespace libyuv {
 extern "C" {
@@ -166,6 +178,7 @@ LIBYUV_API SAFEBUFFERS int ArmCpuCaps(const char* cpuinfo_name) {
   return features;
 }
 
+#ifdef __aarch64__
 #ifdef __linux__
 // Define hwcap values ourselves: building with an old auxv header where these
 // hwcap values are not defined should not prevent features from being enabled.
@@ -194,17 +207,63 @@ LIBYUV_API SAFEBUFFERS int AArch64CpuCaps(unsigned long hwcap,
   }
   return features;
 }
-#else  // !defined(__linux__)
+
+#elif defined(_WIN32)
 // For AArch64, but public to allow testing on any CPU.
 LIBYUV_API SAFEBUFFERS int AArch64CpuCaps() {
   // Neon is mandatory on AArch64, so enable unconditionally.
   int features = kCpuHasNEON;
 
-  // TODO(libyuv:980) support feature detection on non-Linux platforms.
+  // For more information on IsProcessorFeaturePresent(), see:
+  // https://learn.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-isprocessorfeaturepresent#parameters
+#ifdef PF_ARM_V82_DP_INSTRUCTIONS_AVAILABLE
+  if (IsProcessorFeaturePresent(PF_ARM_V82_DP_INSTRUCTIONS_AVAILABLE)) {
+    features |= kCpuHasNeonDotProd;
+  }
+#endif
+  // No Neon I8MM or SVE feature detection available here at time of writing.
+  return features;
+}
+
+#elif defined(__APPLE__)
+static bool have_feature(const char* feature) {
+  // For more information on sysctlbyname(), see:
+  // https://developer.apple.com/documentation/kernel/1387446-sysctlbyname/determining_instruction_set_characteristics
+  int64_t feature_present = 0;
+  size_t size = sizeof(feature_present);
+  if (sysctlbyname(feature, &feature_present, &size, NULL, 0) != 0) {
+    return false;
+  }
+  return feature_present;
+}
+
+// For AArch64, but public to allow testing on any CPU.
+LIBYUV_API SAFEBUFFERS int AArch64CpuCaps() {
+  // Neon is mandatory on AArch64, so enable unconditionally.
+  int features = kCpuHasNEON;
+
+  if (have_feature("hw.optional.arm.FEAT_DotProd")) {
+    features |= kCpuHasNeonDotProd;
+  }
+  if (have_feature("hw.optional.arm.FEAT_I8MM")) {
+    features |= kCpuHasNeonI8MM;
+  }
+  // No SVE feature detection available here at time of writing.
+  return features;
+}
+
+#else  // !defined(__linux__) && !defined(_WIN32) && !defined(__APPLE__)
+// For AArch64, but public to allow testing on any CPU.
+LIBYUV_API SAFEBUFFERS int AArch64CpuCaps() {
+  // Neon is mandatory on AArch64, so enable unconditionally.
+  int features = kCpuHasNEON;
+
+  // TODO(libyuv:980) support feature detection on other platforms.
 
   return features;
 }
 #endif
+#endif  // defined(__aarch64__)
 
 LIBYUV_API SAFEBUFFERS int RiscvCpuCaps(const char* cpuinfo_name) {
   char cpuinfo_line[512];

unit_test/cpu_test.cc

@@ -273,7 +273,7 @@ TEST_F(LibYUVBaseTest, TestLinuxArm) {
 #endif
 }
 
-#ifdef __linux__
+#if defined(__linux__) && defined(__aarch64__)
 TEST_F(LibYUVBaseTest, TestLinuxAArch64) {
   // Values taken from a Cortex-A57 machine, only Neon available.
   EXPECT_EQ(kCpuHasNEON, AArch64CpuCaps(0xffU, 0x0U));