Spin off just SkLazyFnPtr from 305513002.

The memory barrier in SkOnce is a perf regression for sk_mem{set,cpy} in
SkUtils on ARM.  We can do a lot better for function pointers.

BUG=skia:

Committed: http://code.google.com/p/skia/source/detail?r=14929

R=bungeman@google.com, mtklein@google.com

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/305753002

git-svn-id: http://skia.googlecode.com/svn/trunk@14938 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 16 insertions, 34 deletions

diff --git a/src/core/SkUtils.cpp b/src/core/SkUtils.cpp
index ca18e0cb2d..591a198c65 100644
--- a/src/core/SkUtils.cpp
+++ b/src/core/SkUtils.cpp
@@ -8,7 +8,7 @@
 
 
 #include "SkUtils.h"
-#include "SkOnce.h"
+#include "SkLazyFnPtr.h"
 
 #if 0
 #define assign_16_longs(dst, value)             \
@@ -113,52 +113,34 @@ static void sk_memcpy32_portable(uint32_t dst[], const uint32_t src[], int count
     memcpy(dst, src, count * sizeof(uint32_t));
 }
 
-static void choose_memset16(SkMemset16Proc* proc) {
-    *proc = SkMemset16GetPlatformProc();
-    if (NULL == *proc) {
-        *proc = &sk_memset16_portable;
-    }
+static SkMemset16Proc choose_memset16() {
+    SkMemset16Proc proc = SkMemset16GetPlatformProc();
+    return proc ? proc : sk_memset16_portable;
 }
 
 void sk_memset16(uint16_t dst[], uint16_t value, int count) {
-    SK_DECLARE_STATIC_ONCE(once);
-    static SkMemset16Proc proc = NULL;
-    SkOnce(&once, choose_memset16, &proc);
-    SkASSERT(proc != NULL);
-
-    return proc(dst, value, count);
+    SK_DECLARE_STATIC_LAZY_FN_PTR(SkMemset16Proc, choice);
+    return choice.get(choose_memset16)(dst, value, count);
 }
 
-static void choose_memset32(SkMemset32Proc* proc) {
-    *proc = SkMemset32GetPlatformProc();
-    if (NULL == *proc) {
-        *proc = &sk_memset32_portable;
-    }
+static SkMemset32Proc choose_memset32() {
+    SkMemset32Proc proc = SkMemset32GetPlatformProc();
+    return proc ? proc : sk_memset32_portable;
 }
 
 void sk_memset32(uint32_t dst[], uint32_t value, int count) {
-    SK_DECLARE_STATIC_ONCE(once);
-    static SkMemset32Proc proc = NULL;
-    SkOnce(&once, choose_memset32, &proc);
-    SkASSERT(proc != NULL);
-
-    return proc(dst, value, count);
+    SK_DECLARE_STATIC_LAZY_FN_PTR(SkMemset32Proc, choice);
+    return choice.get(choose_memset32)(dst, value, count);
 }
 
-static void choose_memcpy32(SkMemcpy32Proc* proc) {
-    *proc = SkMemcpy32GetPlatformProc();
-    if (NULL == *proc) {
-        *proc = &sk_memcpy32_portable;
-    }
+static SkMemcpy32Proc choose_memcpy32() {
+    SkMemcpy32Proc proc = SkMemcpy32GetPlatformProc();
+    return proc ? proc : sk_memcpy32_portable;
 }
 
 void sk_memcpy32(uint32_t dst[], const uint32_t src[], int count) {
-    SK_DECLARE_STATIC_ONCE(once);
-    static SkMemcpy32Proc proc = NULL;
-    SkOnce(&once, choose_memcpy32, &proc);
-    SkASSERT(proc != NULL);
-
-    return proc(dst, src, count);
+    SK_DECLARE_STATIC_LAZY_FN_PTR(SkMemcpy32Proc, choice);
+    return choice.get(choose_memcpy32)(dst, src, count);
 }
 
 ///////////////////////////////////////////////////////////////////////////////