Fix race in supports_simd().

src/opts/opts_check_x86.cpp

 /*
  * Copyright 2009 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmapFilter_opts_SSE2.h"
 #include "SkBitmapProcState_opts_SSE2.h"
 #include "SkBitmapProcState_opts_SSSE3.h"
 #include "SkBitmapScaler.h"
 #include "SkBlitMask.h"
 #include "SkBlitRect_opts_SSE2.h"
 #include "SkBlitRow.h"
 #include "SkBlitRow_opts_SSE2.h"
 #include "SkBlitRow_opts_SSE4.h"
 #include "SkBlurImage_opts_SSE2.h"
 #include "SkBlurImage_opts_SSE4.h"
+#include "SkLazyPtr.h"
 #include "SkMorphology_opts.h"
 #include "SkMorphology_opts_SSE2.h"
 #include "SkRTConf.h"
 #include "SkUtils.h"
 #include "SkUtils_opts_SSE2.h"
 #include "SkXfermode.h"
 #include "SkXfermode_proccoeff.h"
 
 #if defined(_MSC_VER) && defined(_WIN64)
 #include <intrin.h>
@@ skipping 43 matching lines @@
         : "a"(info_type)
     );
 }
 #endif
 
 ////////////////////////////////////////////////////////////////////////////////
 
 /* Fetch the SIMD level directly from the CPU, at run-time.
  * Only checks the levels needed by the optimizations in this file.
  */
-static int get_SIMD_level() {
-    int cpu_info[4] = { 0 };
+namespace {  // get_SIMD_level() technically must have external linkage, so no static.
+int* get_SIMD_level() {
+    int cpu_info[4] = { 0, 0, 0, 0 };
+    getcpuid(1, cpu_info);
 
-    getcpuid(1, cpu_info);
+    int* level = SkNEW(int);
+
     if ((cpu_info[2] & (1<<20)) != 0) {
-        return SK_CPU_SSE_LEVEL_SSE42;
+        *level = SK_CPU_SSE_LEVEL_SSE42;
     } else if ((cpu_info[2] & (1<<19)) != 0) {
-        return SK_CPU_SSE_LEVEL_SSE41;
+        *level = SK_CPU_SSE_LEVEL_SSE41;
     } else if ((cpu_info[2] & (1<<9)) != 0) {
-        return SK_CPU_SSE_LEVEL_SSSE3;
+        *level = SK_CPU_SSE_LEVEL_SSSE3;
     } else if ((cpu_info[3] & (1<<26)) != 0) {
-        return SK_CPU_SSE_LEVEL_SSE2;
+        *level = SK_CPU_SSE_LEVEL_SSE2;
     } else {
-        return 0;
+        *level = 0;
     }
+    return level;
 }
+} // namespace
+
+SK_DECLARE_STATIC_LAZY_PTR(int, gSIMDLevel, get_SIMD_level);
 
 /* Verify that the requested SIMD level is supported in the build.
  * If not, check if the platform supports it.
  */
 static inline bool supports_simd(int minLevel) {
 #if defined(SK_CPU_SSE_LEVEL)
     if (minLevel <= SK_CPU_SSE_LEVEL) {
         return true;
     } else
 #endif
     {
 #if defined(SK_BUILD_FOR_ANDROID_FRAMEWORK)
         /* For the Android framework we should always know at compile time if the device
          * we are building for supports SSSE3.  The one exception to this rule is on the
          * emulator where we are compiled without the -mssse3 option (so we have no
          * SSSE3 procs) but can be run on a host machine that supports SSSE3
          * instructions. So for that particular case we disable our SSSE3 options.
          */
         return false;
 #else
-        static int gSIMDLevel = get_SIMD_level();
-        return (minLevel <= gSIMDLevel);
+        return minLevel <= *gSIMDLevel.get();
 #endif
     }
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 
 SK_CONF_DECLARE( bool, c_hqfilter_sse, "bitmap.filter.highQualitySSE", true, "Use SSE optimized version of high quality image filters");
 
 void SkBitmapScaler::PlatformConvolutionProcs(SkConvolutionProcs* procs) {
     if (supports_simd(SK_CPU_SSE_LEVEL_SSE2)) {
@@ skipping 262 matching lines @@
     } else {
         return SkPlatformXfermodeFactory_impl(rec, mode);
     }
 }
 
 SkXfermodeProc SkPlatformXfermodeProcFactory(SkXfermode::Mode mode);
 
 SkXfermodeProc SkPlatformXfermodeProcFactory(SkXfermode::Mode mode) {
     return NULL;
 }