Better performance for -LayoutUnit

third_party/WebKit/Source/wtf/SaturatedArithmetic.h

 /*
  * Copyright (c) 2012, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 55 matching lines @@
 
     // Can only overflow if the signed bit of the two input values differ. If
     // the signed bit of the result and the first value differ it overflowed.
 
     if ((ua ^ ub) & (result ^ ua) & (1 << 31))
         return std::numeric_limits<int>::max() + (ua >> 31);
 
     return result;
 }
 
+ALWAYS_INLINE int32_t saturatedNegative(int32_t a)
+{
+    if (UNLIKELY(a == std::numeric_limits<int>::min()))
+        return std::numeric_limits<int>::max();
+    return -a;
+}
+
 inline int getMaxSaturatedSetResultForTesting(int FractionalShift)
 {
     // For C version the set function maxes out to max int, this differs from
     // the ARM asm version, see SaturatedArithmetiARM.h for the equivalent asm
     // version.
     return std::numeric_limits<int>::max();
 }
 
 inline int getMinSaturatedSetResultForTesting(int FractionalShift)
 {
@@ skipping 26 matching lines @@
         std::numeric_limits<int>::max() >> FractionalShift;
 
     if (value >= intMaxForLayoutUnit)
         return std::numeric_limits<int>::max();
 
     return value << FractionalShift;
 }
 
 #endif // CPU(ARM) && COMPILER(GCC)
 #endif // SaturatedArithmetic_h