Implement some intrinsics on x64, fix a bug in ia32 intrinciscs (must return false if there is a fa…

runtime/vm/assembler_x64.cc

Index: runtime/vm/assembler_x64.cc
===================================================================
--- runtime/vm/assembler_x64.cc	(revision 7950)
+++ runtime/vm/assembler_x64.cc	(working copy)
@@ -524,6 +524,17 @@
 }
 
 
+void Assembler::comisd(XmmRegister a, XmmRegister b) {
+  ASSERT(a <= XMM7);
+  ASSERT(b <= XMM7);
+  AssemblerBuffer::EnsureCapacity ensured(&buffer_);
+  EmitUint8(0x66);
+  EmitUint8(0x0F);
+  EmitUint8(0x2F);
+  EmitXmmRegisterOperand(a, b);
+}
+
+
 void Assembler::xchgl(Register dst, Register src) {
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);
   Operand operand(src);