Move 'as' precedence up to just above relational; support indexing str and vec by all integral types. Closes #94.

Author: graydon

src/Makefile

@@ -464,6 +464,7 @@ TEST_XFAILS_LLVM := $(TASK_XFAILS) \
                       i8-incr.rs \
                       import.rs \
                       inner-module.rs \
+                      integral-indexing.rs \
                       iter-range.rs \
                       iter-ret.rs \
                       large-records.rs \

src/boot/be/x86.ml

@@ -1936,15 +1936,20 @@ let zero (dst:Il.cell) (count:Il.operand) : Asm.frag =
 ;;
 
 let mov (signed:bool) (dst:Il.cell) (src:Il.operand) : Asm.frag =
-  if is_ty8 (Il.cell_scalar_ty dst) || is_ty8 (Il.operand_scalar_ty src)
+  if is_ty8 (Il.cell_scalar_ty dst)
   then
     begin
-      (match dst with
-           Il.Reg (Il.Hreg r, _)
-           -> assert (is_ok_r8 r) | _ -> ());
-      (match src with
-           Il.Cell (Il.Reg (Il.Hreg r, _))
-           -> assert (is_ok_r8 r) | _ -> ());
+      match dst with
+          Il.Reg (Il.Hreg r, _) -> assert (is_ok_r8 r)
+        | _ -> ()
+    end;
+
+  if is_ty8 (Il.operand_scalar_ty src)
+  then
+    begin
+      match src with
+          Il.Cell (Il.Reg (Il.Hreg r, _)) -> assert (is_ok_r8 r)
+        | _ -> ()
     end;
 
   match (signed, dst, src) with

src/boot/fe/pexp.ml

@@ -817,11 +817,33 @@ and parse_or_pexp (ps:pstate) : pexp =
     step lhs
 
 
+and parse_as_pexp (ps:pstate) : pexp =
+  let apos = lexpos ps in
+  let pexp = ctxt "as pexp" parse_or_pexp ps in
+  let rec step accum =
+    match peek ps with
+        AS ->
+          bump ps;
+          let tapos = lexpos ps in
+          let t = parse_ty ps in
+          let bpos = lexpos ps in
+          let t = span ps tapos bpos t in
+          let node =
+            span ps apos bpos
+              (PEXP_unop ((Ast.UNOP_cast t), accum))
+          in
+            step node
+
+      | _ -> accum
+  in
+    step pexp
+
+
 and parse_relational_pexp (ps:pstate) : pexp =
   let name = "relational pexp" in
   let apos = lexpos ps in
-  let lhs = ctxt (name ^ " lhs") parse_or_pexp ps in
-  let build = binop_build ps name apos parse_or_pexp in
+  let lhs = ctxt (name ^ " lhs") parse_as_pexp ps in
+  let build = binop_build ps name apos parse_as_pexp in
   let rec step accum =
     match peek ps with
         LT -> build accum step Ast.BINOP_lt
@@ -883,30 +905,8 @@ and parse_oror_pexp (ps:pstate) : pexp =
     step lhs
 
 
-and parse_as_pexp (ps:pstate) : pexp =
-  let apos = lexpos ps in
-  let pexp = ctxt "as pexp" parse_oror_pexp ps in
-  let rec step accum =
-    match peek ps with
-        AS ->
-          bump ps;
-          let tapos = lexpos ps in
-          let t = parse_ty ps in
-          let bpos = lexpos ps in
-          let t = span ps tapos bpos t in
-          let node =
-            span ps apos bpos
-              (PEXP_unop ((Ast.UNOP_cast t), accum))
-          in
-            step node
-
-      | _ -> accum
-  in
-    step pexp
-
-
 and parse_pexp (ps:pstate) : pexp =
-  parse_as_pexp ps
+  parse_oror_pexp ps
 
 and parse_mutable_and_pexp (ps:pstate) : (Ast.mutability * pexp) =
   let mutability = parse_mutability ps in

src/boot/me/trans.ml

@@ -914,7 +914,8 @@ let trans_visitor
       let atop = trans_atom at in
       let unit_sz = ty_sz_in_current_frame ty in
       let idx = next_vreg_cell word_sty in
-        emit (Il.binary Il.UMUL idx atop unit_sz);
+        mov idx atop;
+        emit (Il.binary Il.UMUL idx (Il.Cell idx) unit_sz);
         let elt_mem = trans_bounds_check (deref cell) (Il.Cell idx) in
           (Il.Mem (elt_mem, referent_type abi ty), ty)
     in

src/boot/me/type.ml

@@ -380,19 +380,20 @@ let check_stmt (cx:Semant.ctxt) : (fn_ctx -> Ast.stmt -> unit) =
               sprintf_itype ()
 
         | `Type (Ast.TY_vec ty_vec), Ast.COMP_atom atom ->
-            demand Ast.TY_int (check_atom atom);
+            demand_integer (check_atom atom);
             LTYPE_mono ty_vec
 
         | `Type (Ast.TY_vec _), _ ->
-            Common.err None "the vector type '%a' must be indexed via an int"
+            Common.err None
+              "the vector type '%a' must be indexed by an integral type"
               sprintf_itype ()
 
         | `Type Ast.TY_str, Ast.COMP_atom atom ->
-            demand Ast.TY_int (check_atom atom);
+            demand_integer (check_atom atom);
             LTYPE_mono (Ast.TY_mach Common.TY_u8)
 
         | `Type Ast.TY_str, _ ->
-            Common.err None "strings must be indexed via an int"
+            Common.err None "strings must be indexed by an integral type"
 
         | `Type (Ast.TY_box ty_box), Ast.COMP_deref -> LTYPE_mono ty_box
 

src/test/run-pass/integral-indexing.rs

@@ -0,0 +1,22 @@
+// This is a testcase for issue #94.
+
+fn main() {
+
+  let vec[int] v = vec(0, 1, 2, 3, 4, 5);
+  let str s = "abcdef";
+  check (v.(3u) == 3);
+  check (v.(3u8) == 3);
+  check (v.(3i8) == 3);
+  check (v.(3u32) == 3);
+  check (v.(3i32) == 3);
+
+  log v.(3u8);
+
+  check (s.(3u) == 'd' as u8);
+  check (s.(3u8) == 'd' as u8);
+  check (s.(3i8) == 'd' as u8);
+  check (s.(3u32) == 'd' as u8);
+  check (s.(3i32) == 'd' as u8);
+
+  log s.(3u8);
+}