Lay groundwork for SkOpts.

src/core/SkOpts.cpp

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkOnce.h"
+#include "SkOpts.h"
+
+#if defined(SK_CPU_X86)
+    #if defined(SK_BUILD_FOR_WIN32)
+        #include <intrin.h>
+        static void cpuid(uint32_t abcd[4]) { __cpuid((int*)abcd, 1); }
+    #else
+        #include <cpuid.h>
+        static void cpuid(uint32_t abcd[4]) { __get_cpuid(1, abcd+0, abcd+1, abcd+2, abcd+3); }
+    #endif
+#elif !defined(SK_ARM_HAS_NEON) && defined(SK_CPU_ARM32) && defined(SK_BUILD_FOR_ANDROID)
+    #include <cpu-features.h>
+#endif
+
+namespace SkOpts {
+    // (Define default function pointer values here...)
+
+    // Each Init_foo() is defined in src/opts/SkOpts_foo.cpp.
+    void Init_sse2();
+    void Init_ssse3();
+    void Init_sse41();
+    void Init_neon();
+    //TODO: _dsp2, _armv7, _armv8, _x86, _x86_64, _sse42, _avx, avx2, ... ?
+
+    static void init() {
+    #if defined(SK_CPU_X86)
+        uint32_t abcd[] = {0,0,0,0};
+        cpuid(abcd);
+        if (abcd[3] & (1<<26)) { Init_sse2(); }
+        if (abcd[2] & (1<< 9)) { Init_ssse3(); }
+        if (abcd[2] & (1<<19)) { Init_sse41(); }
+    #elif defined(SK_ARM_HAS_NEON)
+        Init_neon();
+    #elif defined(SK_CPU_ARM32) && defined(SK_BUILD_FOR_ANDROID)
+        if (android_getCpuFeatures() & ANDROID_CPU_ARM_FEATURE_NEON) { Init_neon(); }
+    #endif
+    }
+
+    SK_DECLARE_STATIC_ONCE(gInitOnce);
+    void Init() { SkOnce(&gInitOnce, init); }
+
+#if SK_ALLOW_STATIC_GLOBAL_INITIALIZERS
+    static struct AutoInit {
+        AutoInit() { Init(); }
+    } gAutoInit;
+#endif
+}