move zero-init to sk_malloc for masks

Bug: skia:
Change-Id: I75d557068bdcd9e9f7e380e4fa447f9d83dd1554
Reviewed-on: https://skia-review.googlesource.com/98200
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Reed <reed@google.com>

include/core/SkMask.h

@@ -114,7 +114,11 @@ struct SkMask {
      */
     void* getAddr(int x, int y) const;
 
-    static uint8_t* AllocImage(size_t bytes);
+    enum AllocType {
+        kUninit_Alloc,
+        kZeroInit_Alloc,
+    };
+    static uint8_t* AllocImage(size_t bytes, AllocType = kUninit_Alloc);
     static void FreeImage(void* image);
 
     enum CreateMode {

src/core/SkDraw.cpp

@@ -1730,8 +1730,7 @@ bool SkDraw::DrawToMask(const SkPath& devPath, const SkIRect* clipBounds,
             // we're too big to allocate the mask, abort
             return false;
         }
-        mask->fImage = SkMask::AllocImage(size);
-        memset(mask->fImage, 0, mask->computeImageSize());
+        mask->fImage = SkMask::AllocImage(size, SkMask::kZeroInit_Alloc);
     }
 
     if (SkMask::kJustComputeBounds_CreateMode != mode) {

src/core/SkMask.cpp

@@ -6,10 +6,8 @@
  */
 
 #include "SkMask.h"
-
 #include "SkMalloc.h"
-
-//#define TRACK_SKMASK_LIFETIME
+#include "SkSafeMath.h"
 
 /** returns the product if it is positive and fits in 31 bits. Otherwise this
     returns 0.
@@ -34,36 +32,22 @@ size_t SkMask::computeTotalImageSize() const {
     return size;
 }
 
-#ifdef TRACK_SKMASK_LIFETIME
-    static int gCounter;
-#endif
-
 /** We explicitly use this allocator for SkBimap pixels, so that we can
     freely assign memory allocated by one class to the other.
 */
-uint8_t* SkMask::AllocImage(size_t size) {
-#ifdef TRACK_SKMASK_LIFETIME
-    SkDebugf("SkMask::AllocImage %d\n", gCounter++);
-#endif
-    size_t aligned_size = std::numeric_limits<size_t>::max();
-
-    // Expand size to next multiple of four.
-    size_t adjustment = 3;
-    if (size + adjustment > size) {
-        aligned_size = (size + adjustment) & ~adjustment;
+uint8_t* SkMask::AllocImage(size_t size, AllocType at) {
+    size_t aligned_size = SkSafeMath::Align4(size);
+    unsigned flags = SK_MALLOC_THROW;
+    if (at == kZeroInit_Alloc) {
+        flags |= SK_MALLOC_ZERO_INITIALIZE;
     }
-    return static_cast<uint8_t*>(sk_malloc_throw(aligned_size));
+    return static_cast<uint8_t*>(sk_malloc_flags(aligned_size, flags));
 }
 
 /** We explicitly use this allocator for SkBimap pixels, so that we can
     freely assign memory allocated by one class to the other.
 */
 void SkMask::FreeImage(void* image) {
-#ifdef TRACK_SKMASK_LIFETIME
-    if (image) {
-        SkDebugf("SkMask::FreeImage  %d\n", --gCounter);
-    }
-#endif
     sk_free(image);
 }
 

src/core/SkSafeMath.h

@@ -51,6 +51,10 @@ public:
     // These saturate to their results
     static size_t Add(size_t x, size_t y);
     static size_t Mul(size_t x, size_t y);
+    static size_t Align4(size_t x) {
+        SkSafeMath safe;
+        return safe.alignUp(x, 4);
+    }
 
 private:
     uint32_t mul32(uint32_t x, uint32_t y) {

src/effects/SkBlurMaskFilter.cpp

@@ -347,13 +347,10 @@ static bool prepare_to_draw_into_mask(const SkRect& bounds, SkMask* mask) {
     mask->fRowBytes = SkAlign4(mask->fBounds.width());
     mask->fFormat = SkMask::kA8_Format;
     const size_t size = mask->computeImageSize();
-    mask->fImage = SkMask::AllocImage(size);
+    mask->fImage = SkMask::AllocImage(size, SkMask::kZeroInit_Alloc);
     if (nullptr == mask->fImage) {
         return false;
     }
-
-    // FIXME: use sk_calloc in AllocImage?
-    sk_bzero(mask->fImage, size);
     return true;
 }