Microoptimization to regexps.

src/x64/code-stubs-x64.cc

 // Copyright 2012 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 3217 matching lines @@
   // rax: JSArray.
   // rcx: FixedArray.
   // rbx: Number of elements in array as int32.
 
   // Set map.
   __ LoadRoot(kScratchRegister, Heap::kFixedArrayMapRootIndex);
   __ movq(FieldOperand(rcx, HeapObject::kMapOffset), kScratchRegister);
   // Set length.
   __ Integer32ToSmi(rdx, rbx);
   __ movq(FieldOperand(rcx, FixedArray::kLengthOffset), rdx);
-  // Fill contents of fixed-array with the-hole.
-  __ LoadRoot(rdx, Heap::kTheHoleValueRootIndex);
+  // Fill contents of fixed-array with undefined.
+  __ LoadRoot(rdx, Heap::kUndefinedValueRootIndex);
   __ lea(rcx, FieldOperand(rcx, FixedArray::kHeaderSize));
-  // Fill fixed array elements with hole.
+  // Fill fixed array elements with undefined.
   // rax: JSArray.
   // rbx: Number of elements in array that remains to be filled, as int32.
   // rcx: Start of elements in FixedArray.
-  // rdx: the hole.
+  // rdx: undefined.
   Label loop;
   __ testl(rbx, rbx);
   __ bind(&loop);
   __ j(less_equal, &done);  // Jump if rcx is negative or zero.
   __ subl(rbx, Immediate(1));
   __ movq(Operand(rcx, rbx, times_pointer_size, 0), rdx);
   __ jmp(&loop);
 
   __ bind(&done);
   __ ret(3 * kPointerSize);
@@ skipping 3226 matching lines @@
 #endif
 
   __ Ret();
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64