Support conversion of clamped double values for pixel arrays in Crankshaft.

src/x64/macro-assembler-x64.h

 // Copyright 2011 the V8 project authors. 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
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 747 matching lines @@
   // registers map and instance_type can be the same as heap_object.
   Condition IsObjectStringType(Register heap_object,
                                Register map,
                                Register instance_type);
 
   // FCmp compares and pops the two values on top of the FPU stack.
   // The flag results are similar to integer cmp, but requires unsigned
   // jcc instructions (je, ja, jae, jb, jbe, je, and jz).
   void FCmp();
 
+  void ClampUint8(Register reg);
+
+  void ClampDoubleToUint8(XMMRegister input_reg,
+                          XMMRegister temp_xmm_reg,
+                          Register result_reg,
+                          Register temp_reg);
+
   // Abort execution if argument is not a number. Used in debug code.
   void AbortIfNotNumber(Register object);
 
   // Abort execution if argument is a smi. Used in debug code.
   void AbortIfSmi(Register object);
 
   // Abort execution if argument is not a smi. Used in debug code.
   void AbortIfNotSmi(Register object);
   void AbortIfNotSmi(const Operand& object);
 
@@ skipping 475 matching lines @@
     masm->popfd();                                                        \
   }                                                                       \
   masm->
 #else
 #define ACCESS_MASM(masm) masm->
 #endif
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_MACRO_ASSEMBLER_X64_H_