Stub out a small portion of the x64 assembler.

src/x64/assembler-x64.h

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+#ifndef V8_X64_ASSEMBLER_X64_H_
+#define V8_X64_ASSEMBLER_X64_H_
+
+// TODO(x64): This is a temporary stub, we will need to implement this code.
+
+namespace v8 { namespace internal {
+
+struct Register {
+  bool is_valid() const  { return 0 <= code_ && code_ < 8; }
+  bool is(Register reg) const  { return code_ == reg.code_; }
+  // eax, ebx, ecx and edx are byte registers, the rest are not.
+  bool is_byte_register() const  { return code_ <= 3; }
+  int code() const  {
+    ASSERT(is_valid());
+    return code_;
+  }
+  int bit() const  {
+    ASSERT(is_valid());
+    return 1 << code_;
+  }
+
+  // (unfortunately we can't make this private in a struct)

[Kevin Millikin (Chromium), 2009/05/05 15:48:00]

I've never liked this  comment.

+  int code_;
+};
+
+const int kNumRegisters = 8;
+extern Register no_reg;
+
+enum Condition {
+  // any value < 0 is considered no_condition
+  no_condition  = -1,
+
+  overflow      =  0,
+  no_overflow   =  1,
+  below         =  2,
+  above_equal   =  3,
+  equal         =  4,
+  not_equal     =  5,
+  below_equal   =  6,
+  above         =  7,
+  negative      =  8,
+  positive      =  9,
+  parity_even   = 10,
+  parity_odd    = 11,
+  less          = 12,
+  greater_equal = 13,
+  less_equal    = 14,
+  greater       = 15,
+
+  // aliases
+  carry         = below,
+  not_carry     = above_equal,
+  zero          = equal,
+  not_zero      = not_equal,
+  sign          = negative,
+  not_sign      = positive
+};
+
+enum Hint {
+  no_hint = 0,
+  not_taken = 0x2e,
+  taken = 0x3e
+};
+
+} }  // namespace v8::internal
+
+#endif  // V8_X64_ASSEMBLER_X64_H_