From c09e2af17fab03d3d36c20e5201a560c3e4c233e Mon Sep 17 00:00:00 2001
From: mtklein <mtklein@chromium.org>
Date: Mon, 13 Oct 2014 12:48:16 -0700
Subject: Fix race in supports_simd().

Local statics are not thread safe in Chrome.  Use an SkLazyPtr instead.

See https://code.google.com/p/chromium/issues/detail?id=418041

BUG=418041

Review URL: https://codereview.chromium.org/655573002
---
 src/opts/opts_check_x86.cpp | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)

(limited to 'src')

diff --git a/src/opts/opts_check_x86.cpp b/src/opts/opts_check_x86.cpp
index 55eb843312..8fec2ba69c 100644
--- a/src/opts/opts_check_x86.cpp
+++ b/src/opts/opts_check_x86.cpp
@@ -16,6 +16,7 @@
 #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"
@@ -79,22 +80,29 @@ static inline void getcpuid(int info_type, int info[4]) {
 /* 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);
+
+    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.
@@ -115,8 +123,7 @@ static inline bool supports_simd(int minLevel) {
          */
         return false;
 #else
-        static int gSIMDLevel = get_SIMD_level();
-        return (minLevel <= gSIMDLevel);
+        return minLevel <= *gSIMDLevel.get();
 #endif
     }
 }
-- 
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