adding amd64 architecture

library/compiler/amd64/architecture.factor

@@ -0,0 +1,24 @@
+IN: compiler-backend
+USING: assembler compiler-backend kernel sequences ;
+
+! AMD64 register assignments
+! RAX RCX RDX RSI RDI R8 R9 R10 R11 vregs
+! R12 datastack
+! R13 callstack
+
+: fixnum-imm? ( -- ? )
+    #! Can fixnum operations take immediate operands?
+    t ; inline
+
+: vregs ( -- n )
+    #! Number of vregs
+    3 ; inline
+
+M: vreg v>operand vreg-n { RAX RCX RDX RSI RDI R8 R9 R10 R11 } nth ;
+
+! FIXME
+M: int-regs fastcall-regs drop 0 ;
+M: int-regs reg-class-size drop 4 ;
+M: float-regs fastcall-regs drop 0 ;
+
+: dual-fp/int-regs? f ;