More intrinsification x64: array index load and store.

runtime/vm/assembler_x64.cc

Index: runtime/vm/assembler_x64.cc
===================================================================
--- runtime/vm/assembler_x64.cc	(revision 7968)
+++ runtime/vm/assembler_x64.cc	(working copy)
@@ -828,10 +828,20 @@
 
 
 void Assembler::addq(const Address& address, const Immediate& imm) {
-  UNIMPLEMENTED();
+  // TODO(srdjan): Implement shorter version for imm32.
+  movq(TMP, imm);
+  addq(address, TMP);
 }
 
 
+void Assembler::addq(const Address& address, Register reg) {
+  AssemblerBuffer::EnsureCapacity ensured(&buffer_);
+  EmitOperandREX(reg, address, REX_W);
+  EmitUint8(0x01);
+  EmitOperand(reg & 7, address);
+}
+
+
 void Assembler::subl(Register dst, Register src) {
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);
   Operand operand(src);