Revert "Revert of https://codereview.chromium.org/113823003/"

src/core/SkBitmap.cpp

Index: src/core/SkBitmap.cpp
diff --git a/src/core/SkBitmap.cpp b/src/core/SkBitmap.cpp
index d4c3a47d81f42519dbb08c15c9fbb6ad5cbcb4cf..11c7cbd69c289991ea25c8894a6b62037ec34a2c 100644
--- a/src/core/SkBitmap.cpp
+++ b/src/core/SkBitmap.cpp
@@ -24,10 +24,6 @@
 #include "SkPackBits.h"
 #include <new>
 
-static bool isPos32Bits(const Sk64& value) {
-    return !value.isNeg() && value.is32();
-}
-
 struct MipLevel {
     void*       fPixels;
     uint32_t    fRowBytes;
@@ -44,14 +40,12 @@ struct SkBitmap::MipMap : SkNoncopyable {
         if (levelCount < 0) {
             return NULL;
         }
-        Sk64 size;
-        size.setMul(levelCount + 1, sizeof(MipLevel));
-        size.add(sizeof(MipMap));
-        size.add(SkToS32(pixelSize));
-        if (!isPos32Bits(size)) {
+        int64_t size = (levelCount + 1) * sizeof(MipLevel);
+        size += sizeof(MipMap) + pixelSize;
+        if (!sk_64_isS32(size)) {
             return NULL;
         }
-        MipMap* mm = (MipMap*)sk_malloc_throw(size.get32());
+        MipMap* mm = (MipMap*)sk_malloc_throw(sk_64_asS32(size));
         mm->fRefCnt = 1;
         mm->fLevelCount = levelCount;
         return mm;
@@ -185,58 +179,49 @@ size_t SkBitmap::ComputeRowBytes(Config c, int width) {
         return 0;
     }
 
-    Sk64 rowBytes;
-    rowBytes.setZero();
+    int64_t rowBytes = 0;
 
     switch (c) {
         case kNo_Config:
             break;
         case kA8_Config:
         case kIndex8_Config:
-            rowBytes.set(width);
+            rowBytes = width;
             break;
         case kRGB_565_Config:
         case kARGB_4444_Config:
-            rowBytes.set(width);
-            rowBytes.shiftLeft(1);
+            rowBytes = width << 1;
             break;
         case kARGB_8888_Config:
-            rowBytes.set(width);
-            rowBytes.shiftLeft(2);
+            rowBytes = width << 2;
             break;
         default:
             SkDEBUGFAIL("unknown config");
             break;
     }
-    return isPos32Bits(rowBytes) ? rowBytes.get32() : 0;
+    return sk_64_isS32(rowBytes) ? sk_64_asS32(rowBytes) : 0;
 }
 
-Sk64 SkBitmap::ComputeSize64(Config c, int width, int height) {
-    Sk64 size;
-    size.setMul(SkToS32(SkBitmap::ComputeRowBytes(c, width)), height);
-    return size;
+int64_t SkBitmap::ComputeSize64(Config config, int width, int height) {
+    int64_t rowBytes = sk_64_mul(ComputeBytesPerPixel(config), width);
+    return rowBytes * height;
 }
 
 size_t SkBitmap::ComputeSize(Config c, int width, int height) {
-    Sk64 size = SkBitmap::ComputeSize64(c, width, height);
-    return isPos32Bits(size) ? size.get32() : 0;
+    int64_t size = SkBitmap::ComputeSize64(c, width, height);
+    return sk_64_isS32(size) ? sk_64_asS32(size) : 0;
 }
 
-Sk64 SkBitmap::ComputeSafeSize64(Config config,
-                                 uint32_t width,
-                                 uint32_t height,
-                                 size_t rowBytes) {
-    Sk64 safeSize;
-    safeSize.setZero();
+int64_t SkBitmap::ComputeSafeSize64(Config config,
+                                    uint32_t width,
+                                    uint32_t height,
+                                    size_t rowBytes) {
+    int64_t safeSize = 0;
     if (height > 0) {
-        // TODO: Handle the case where the return value from
-        // ComputeRowBytes is more than 31 bits.
-        safeSize.set(SkToS32(ComputeRowBytes(config, width)));
-        Sk64 sizeAllButLastRow;
-        sizeAllButLastRow.setMul(height - 1, SkToS32(rowBytes));
-        safeSize.add(sizeAllButLastRow);
-    }
-    SkASSERT(!safeSize.isNeg());
+        int64_t lastRow = sk_64_mul(ComputeBytesPerPixel(config), width);
+        safeSize = sk_64_mul(height - 1, rowBytes) + lastRow;
+    }
+    SkASSERT(safeSize >= 0);
     return safeSize;
 }
 
@@ -244,8 +229,13 @@ size_t SkBitmap::ComputeSafeSize(Config config,
                                  uint32_t width,
                                  uint32_t height,
                                  size_t rowBytes) {
-    Sk64 safeSize = ComputeSafeSize64(config, width, height, rowBytes);
-    return (safeSize.is32() ? safeSize.get32() : 0);
+    int64_t safeSize = ComputeSafeSize64(config, width, height, rowBytes);
+    int32_t safeSize32 = (int32_t)safeSize;
+    
+    if (safeSize32 != safeSize) {
+        safeSize32 = 0;
+    }
+    return safeSize32;
 }
 
 void SkBitmap::getBounds(SkRect* bounds) const {
@@ -558,10 +548,6 @@ size_t SkBitmap::getSafeSize() const {
             ComputeRowBytes(this->config(), fWidth): 0);
 }
 
-Sk64 SkBitmap::getSafeSize64() const {
-    return ComputeSafeSize64(this->config(), fWidth, fHeight, fRowBytes);
-}
-
 bool SkBitmap::copyPixelsTo(void* const dst, size_t dstSize,
                             size_t dstRowBytes, bool preserveDstPad) const {