Prevent deopt when assigning double values to typed arrays

src/ia32/macro-assembler-ia32.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 219 matching lines @@
                             Register scratch,
                             Label* fail);
 
   // The contents of the scratch register will be overwritten.
   void IsInstanceJSObjectType(Register map, Register scratch, Label* fail);
 
   // FCmp is similar to integer cmp, but requires unsigned
   // jcc instructions (je, ja, jae, jb, jbe, je, and jz).
   void FCmp();
 
+  void ClampUInt8(Register reg) {
+    NearLabel done;
+    test(reg, Immediate(0xFFFFFF00));
+    j(zero, &done);
+    setcc(negative, reg);  // 1 if negative, 0 if positive.
+    dec_b(reg);  // 0 if negative, 255 if positive.
+    bind(&done);
+  }
+
+  void ClampDoubleToUInt8(XMMRegister input_reg, Register result_reg) {
+    NearLabel above_zero;
+    NearLabel done;
+    NearLabel in_bounds;
+    ExternalReference zero = ExternalReference::address_of_zero();
+    movdbl(xmm0, Operand::StaticVariable(zero));
+    ucomisd(input_reg, xmm0);
+    j(above, &above_zero);
+    Set(result_reg, Immediate(0));
+    jmp(&done);
+    bind(&above_zero);
+    ExternalReference uint8_max_value =
+        ExternalReference::address_of_uint8_max_value();
+    movdbl(xmm0, Operand::StaticVariable(uint8_max_value));
+    ucomisd(input_reg, xmm0);
+    j(below_equal, &in_bounds);
+    Set(result_reg, Immediate(255));
+    jmp(&done);
+    bind(&in_bounds);
+    ExternalReference one_half =
+        ExternalReference::address_of_one_half();
+    movdbl(xmm0, Operand::StaticVariable(one_half));
+    addsd(input_reg, xmm0);
+    cvttsd2si(result_reg, Operand(input_reg));
+    bind(&done);
+  }
+
   // Smi tagging support.
   void SmiTag(Register reg) {
     ASSERT(kSmiTag == 0);
     ASSERT(kSmiTagSize == 1);
     add(reg, Operand(reg));
   }
   void SmiUntag(Register reg) {
     sar(reg, kSmiTagSize);
   }
 
@@ skipping 545 matching lines @@
   }                                                                       \
   masm->
 #else
 #define ACCESS_MASM(masm) masm->
 #endif
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_IA32_MACRO_ASSEMBLER_IA32_H_