Implement and test arg_loc

Signed-off-by: Mariano Uvalle <u.g.a.mariano@gmail.com>

hw3/bin/backend.ml

@@ -287,7 +287,18 @@ let compile_lbl_block fn lbl ctxt blk : elem =
 
    [ NOTE: the first six arguments are numbered 0 .. 5 ]
 *)
-let arg_loc (n : int) : operand = failwith "arg_loc not implemented"
+let arg_loc (n : int) : operand =
+  let n64 = Int64.of_int n in
+  let rbp_offset = Int64.mul 8L (Int64.sub n64 4L) in
+  match n with
+  | 0 -> Reg Rdi
+  | 1 -> Reg Rsi
+  | 2 -> Reg Rdx
+  | 3 -> Reg Rcx
+  | 4 -> Reg R08
+  | 5 -> Reg R09
+  | _ -> Ind3 (Lit rbp_offset, Rbp)
+;;
 
 (* We suggest that you create a helper function that computes the
    stack layout for a given function declaration.

hw3/test/studenttests.ml

@@ -1,12 +1,26 @@
 open Util.Assert
+open X86
+open Ll
+module Backend = Llbackend.Backend
+module Driver = Llbackend.Driver
+open Llbackend.Backend
 open Gradedtests
-    
 
 (* These tests are provided by you -- they will be graded manually *)
 
 (* You should also add additional test cases here to help you   *)
 (* debug your program.                                          *)
 
-let provided_tests : suite = [
+let arg_loc_tests =
-  
+  [ "arg_loc_0", assert_eqf (fun () -> arg_loc 0) (Reg Rdi)
-] 
+  ; "arg_loc_1", assert_eqf (fun () -> arg_loc 1) (Reg Rsi)
+  ; "arg_loc_2", assert_eqf (fun () -> arg_loc 2) (Reg Rdx)
+  ; "arg_loc_3", assert_eqf (fun () -> arg_loc 3) (Reg Rcx)
+  ; "arg_loc_4", assert_eqf (fun () -> arg_loc 4) (Reg R08)
+  ; "arg_loc_5", assert_eqf (fun () -> arg_loc 5) (Reg R09)
+  ; "arg_loc_6", assert_eqf (fun () -> arg_loc 6) (Ind3 (Lit 16L, Rbp))
+  ; "arg_loc_100", assert_eqf (fun () -> arg_loc 100) (Ind3 (Lit 768L, Rbp))
+  ]
+;;
+
+let provided_tests : suite = [ Test ("arg_loc_tests", arg_loc_tests) ]