Move Google3-specific stack limitation logic to template classes.

include/core/SkTypes.h

Index: include/core/SkTypes.h
diff --git a/include/core/SkTypes.h b/include/core/SkTypes.h
index 0d31efc6ccf7dd904dd7232b094aedaddbbc6870..4592168bd4d6da020179236511f439cd5cd30937 100644
--- a/include/core/SkTypes.h
+++ b/include/core/SkTypes.h
@@ -606,17 +606,16 @@ private:
 #define SkAutoMalloc(...) SK_REQUIRE_LOCAL_VAR(SkAutoMalloc)
 
 /**
- *  Manage an allocated block of memory. If the requested size is <= kSize, then
- *  the allocation will come from the stack rather than the heap. This object
- *  is the sole manager of the lifetime of the block, so the caller must not
- *  call sk_free() or delete on the block.
+ *  Manage an allocated block of memory. If the requested size is <= kSizeRequested (or slightly
+ *  more), then the allocation will come from the stack rather than the heap. This object is the
+ *  sole manager of the lifetime of the block, so the caller must not call sk_free() or delete on
+ *  the block.
  */
-template <size_t kSize> class SkAutoSMalloc : SkNoncopyable {
+template <size_t kSizeRequested> class SkAutoSMalloc : SkNoncopyable {
 public:
     /**
-     *  Creates initially empty storage. get() returns a ptr, but it is to
-     *  a zero-byte allocation. Must call reset(size) to return an allocated
-     *  block.
+     *  Creates initially empty storage. get() returns a ptr, but it is to a zero-byte allocation.
+     *  Must call reset(size) to return an allocated block.
      */
     SkAutoSMalloc() {
         fPtr = fStorage;
@@ -624,9 +623,8 @@ public:
     }
 
     /**
-     *  Allocate a block of the specified size. If size <= kSize, then the
-     *  allocation will come from the stack, otherwise it will be dynamically
-     *  allocated.
+     *  Allocate a block of the specified size. If size <= kSizeRequested (or slightly more), then
+     *  the allocation will come from the stack, otherwise it will be dynamically allocated.
      */
     explicit SkAutoSMalloc(size_t size) {
         fPtr = fStorage;
@@ -635,8 +633,8 @@ public:
     }
 
     /**
-     *  Free the allocated block (if any). If the block was small enought to
-     *  have been allocated on the stack (size <= kSize) then this does nothing.
+     *  Free the allocated block (if any). If the block was small enough to have been allocated on
+     *  the stack, then this does nothing.
      */
     ~SkAutoSMalloc() {
         if (fPtr != (void*)fStorage) {
@@ -645,18 +643,16 @@ public:
     }
 
     /**
-     *  Return the allocated block. May return non-null even if the block is
-     *  of zero size. Since this may be on the stack or dynamically allocated,
-     *  the caller must not call sk_free() on it, but must rely on SkAutoSMalloc
-     *  to manage it.
+     *  Return the allocated block. May return non-null even if the block is of zero size. Since
+     *  this may be on the stack or dynamically allocated, the caller must not call sk_free() on it,
+     *  but must rely on SkAutoSMalloc to manage it.
      */
     void* get() const { return fPtr; }
 
     /**
-     *  Return a new block of the requested size, freeing (as necessary) any
-     *  previously allocated block. As with the constructor, if size <= kSize
-     *  then the return block may be allocated locally, rather than from the
-     *  heap.
+     *  Return a new block of the requested size, freeing (as necessary) any previously allocated
+     *  block. As with the constructor, if size <= kSizeRequested (or slightly more) then the return
+     *  block may be allocated locally, rather than from the heap.
      */
     void* reset(size_t size,
                 SkAutoMalloc::OnShrink shrink = SkAutoMalloc::kAlloc_OnShrink,
@@ -686,9 +682,20 @@ public:
     }
 
 private:
+    // Align up to 32 bits.
+    static const size_t kSizeAlign4 = SkAlign4(kSizeRequested);
+#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 kMaxBytes = 4 * 1024;
+    static const size_t kSize = kSizeRequested > kMaxBytes ? kMaxBytes : kSizeAlign4;
+#else
+    static const size_t kSize = kSizeAlign4;
+#endif
+
     void*       fPtr;
     size_t      fSize;  // can be larger than the requested size (see kReuse)
-    uint32_t    fStorage[(kSize + 3) >> 2];
+    uint32_t    fStorage[kSize >> 2];
 };
 // Can't guard the constructor because it's a template class.