Move Google3-specific stack limitation logic to template classes. Remove #ifdefs in other files.

include/private/SkTemplates.h

Index: include/private/SkTemplates.h
diff --git a/include/private/SkTemplates.h b/include/private/SkTemplates.h
index 496cf427337664d82ed499412e67168af14f8f5b..c63bfdabe19f9ea34721212e3f4af22d1cb89aed 100644
--- a/include/private/SkTemplates.h
+++ b/include/private/SkTemplates.h
@@ -195,13 +195,13 @@ public:
         }
 
         if (fCount != count) {
-            if (fCount > N) {
+            if (fCount > N_ADJ) {

[mtklein, 2016/02/02 03:04:29]

Ditto here.  It just seems easy to accidentally use N instead of N_ADJ.  Let's
make the user-supplied value have the weird name, e.g. N_REQUESTED, and the
value we're supposed to use be the simple one, e.g. N.

[dogben, 2016/02/02 19:39:34]

Done. I made the naming consistent with SkAutoSMalloc.

                 // 'fArray' was allocated last time so free it now
                 SkASSERT((T*) fStorage != fArray);
                 sk_free(fArray);
             }
 
-            if (count > N) {
+            if (count > N_ADJ) {
                 const uint64_t size64 = sk_64_mul(count, sizeof(T));
                 const size_t size = static_cast<size_t>(size64);
                 if (size != size64) {
@@ -240,10 +240,19 @@ public:
     }
 
 private:
+#if defined(GOOGLE3)
+    // Stack frame size is limited for GOOGLE3. 4k is less than the actual max, but some functions
+    // have multiple large stack allocations.
+    static const int MAX_BYTES = 4 * 1024;
+    static const int N_ADJ = N * sizeof(T) > MAX_BYTES ? MAX_BYTES / sizeof(T) : N;
+#else
+    static const int N_ADJ = N;
+#endif
+
     int     fCount;
     T*      fArray;
     // since we come right after fArray, fStorage should be properly aligned
-    char    fStorage[N * sizeof(T)];
+    char    fStorage[N_ADJ * sizeof(T)];
 };
 
 /** Manages an array of T elements, freeing the array in the destructor.
@@ -322,7 +331,7 @@ public:
     SkAutoSTMalloc() : fPtr(fTStorage) {}
 
     SkAutoSTMalloc(size_t count) {
-        if (count > N) {
+        if (count > N_ADJ) {
             fPtr = (T*)sk_malloc_flags(count * sizeof(T), SK_MALLOC_THROW | SK_MALLOC_TEMP);
         } else {
             fPtr = fTStorage;
@@ -340,7 +349,7 @@ public:
         if (fPtr != fTStorage) {
             sk_free(fPtr);
         }
-        if (count > N) {
+        if (count > N_ADJ) {
             fPtr = (T*)sk_malloc_throw(count * sizeof(T));
         } else {
             fPtr = fTStorage;
@@ -368,10 +377,10 @@ public:
 
     // Reallocs the array, can be used to shrink the allocation.  Makes no attempt to be intelligent
     void realloc(size_t count) {
-        if (count > N) {
+        if (count > N_ADJ) {
             if (fPtr == fTStorage) {
                 fPtr = (T*)sk_malloc_throw(count * sizeof(T));
-                memcpy(fPtr, fTStorage, N * sizeof(T));
+                memcpy(fPtr, fTStorage, N_ADJ * sizeof(T));
             } else {
                 fPtr = (T*)sk_realloc_throw(fPtr, count * sizeof(T));
             }
@@ -381,9 +390,20 @@ public:
     }
 
 private:
+    // Since we use uint32_t storage, we might be able to get more elements for free.
+    static const size_t N_WITH_PADDING = (((N*sizeof(T) + 3) >> 2) << 2) / sizeof(T);
+#if defined(GOOGLE3)
+    // Stack frame size is limited for GOOGLE3. 4k is less than the actual max, but some functions
+    // have multiple large stack allocations.
+    static const size_t MAX_BYTES = 4 * 1024;
+    static const size_t N_ADJ = N * sizeof(T) > MAX_BYTES ? MAX_BYTES / sizeof(T) : N_WITH_PADDING;
+#else
+    static const size_t N_ADJ = N_WITH_PADDING;
+#endif
+
     T*          fPtr;
     union {
-        uint32_t    fStorage32[(N*sizeof(T) + 3) >> 2];
+        uint32_t    fStorage32[(N_ADJ*sizeof(T) + 3) >> 2];
         T           fTStorage[1];   // do NOT want to invoke T::T()
     };
 };