Better performance for -LayoutUnit

third_party/WebKit/Source/wtf/asm/SaturatedArithmeticARM.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SaturatedArithmeticARM_h
 #define SaturatedArithmeticARM_h
 
 #include "wtf/CPU.h"
 #include <limits>
 #include <stdint.h>
@@ skipping 15 matching lines @@
     int32_t result;
 
     asm("qsub %[output],%[first],%[second]"
         :   [output] "=r"  (result)
         :   [first]  "r"   (a),
             [second] "r"   (b));
 
     return result;
 }
 
+ALWAYS_INLINE int32_t saturatedNegative(int32_t a)
+{
+    return saturatedSubtraction(0, a);
+}
+
 inline int getMaxSaturatedSetResultForTesting(int FractionalShift)
 {
     // For ARM Asm version the set function maxes out to the biggest
     // possible integer part with the fractional part zero'd out.
     // e.g. 0x7fffffc0.
     return std::numeric_limits<int>::max() & ~((1 << FractionalShift)-1);
 }
 
 inline int getMinSaturatedSetResultForTesting(int FractionalShift)
 {
@@ skipping 52 matching lines @@
         "lsl  %[output],%[shift]"
         :   [output]    "=r"  (result)
         :   [value]     "r"   (value),
             [saturate]  "n"   (Saturate),
             [shift]     "n"   (FractionalShift));
 
     return result;
 }
 
 #endif // SaturatedArithmeticARM_h