Slight adjustments to shape, rename to type_glue.rs.

Author: graydon

src/comp/middle/shape.rs

@@ -0,0 +1,104 @@
+// The "shape" of a type is best defined as "how a value of a type looks from
+// the standpoint of a certain built-in operation".
+//
+// This is used to collapse take/drop glues that would otherwise be
+// separate. For instance, a boxed tuple of 3 ints and a boxed tuple of 3
+// uints look the same as far as reference count manipulation is concerned, so
+// they get the same shape so that their reference count glues can be
+// collapsed together. To give another example, an int and float have the
+// same (nonexistent!) glue as far as reference counting is concerned, since
+// they aren't reference counted.
+
+import front::ast;
+import middle::trans::variant_info;
+import middle::ty;
+
+type variant_getter = fn(&ast::def_id) -> vec[variant_info];
+
+
+// Reference counting shapes.
+
+tag rc_shape {
+    rs_none;                        // No reference count.
+    rs_ref;                         // Reference counted box.
+    rs_pair;                        // Pair of code/const ptr + rc box.
+    rs_tag(vec[vec[@rc_shape]]);    // Discriminated union.
+    rs_tup(vec[@rc_shape]);         // Tuple.
+}
+
+fn rc_shape_of(&ty::ctxt tcx, variant_getter getter, ty::t t) -> rc_shape {
+    alt (ty::struct(tcx, t)) {
+        // TODO: Or-patterns
+        case (ty::ty_nil) { ret rs_none; }
+        case (ty::ty_bool) { ret rs_none; }
+        case (ty::ty_int) { ret rs_none; }
+        case (ty::ty_uint) { ret rs_none; }
+        case (ty::ty_machine(_)) { ret rs_none; }
+        case (ty::ty_char) { ret rs_none; }
+        case (ty::ty_str) { ret rs_none; }
+        case (ty::ty_tag(?did, ?params)) {
+            let vec[vec[@rc_shape]] result = vec();
+
+            auto vinfos = getter(did);
+            for (variant_info vinfo in vinfos) {
+                let vec[@rc_shape] variant_rcs = vec();
+                for (ty::t typ in vinfo.args) {
+                    auto ty_1 = ty::bind_params_in_type(tcx, typ);
+                    ty_1 = ty::substitute_type_params(tcx, params, ty_1);
+                    variant_rcs += vec(@rc_shape_of(tcx, getter, ty_1));
+                }
+                result += vec(variant_rcs);
+            }
+
+            ret rs_tag(result);
+        }
+        case (ty::ty_box(_)) { ret rs_ref; }
+        case (ty::ty_vec(_)) { ret rs_ref; }
+        case (ty::ty_port(_)) { ret rs_ref; }
+        case (ty::ty_chan(_)) { ret rs_ref; }
+        case (ty::ty_task) { ret rs_ref; }
+        case (ty::ty_tup(?mts)) {
+            let vec[@rc_shape] result = vec();
+            for (ty::mt tm in mts) {
+                result += vec(@rc_shape_of(tcx, getter, tm.ty));
+            }
+            ret rs_tup(result);
+        }
+        case (ty::ty_rec(?fields)) {
+            let vec[@rc_shape] result = vec();
+            for (ty::field fld in fields) {
+                result += vec(@rc_shape_of(tcx, getter, fld.mt.ty));
+            }
+            ret rs_tup(result);
+        }
+        case (ty::ty_fn(_, _, _)) { ret rs_pair; }
+        case (ty::ty_native_fn(_, _, _)) { ret rs_pair; }
+        case (ty::ty_obj(_)) { ret rs_pair; }
+        case (ty::ty_var(_)) { log_err "var in rc_shape_of()"; fail; }
+        case (ty::ty_local(_)) {
+            log_err "local in rc_shape_of()";
+            fail;
+        }
+        case (ty::ty_param(_)) {
+            log_err "param in rc_shape_of()";
+            fail;
+        }
+        case (ty::ty_bound_param(_)) {
+            log_err "bound param in rc::shape_of()";
+            fail;
+        }
+        case (ty::ty_type) { ret rs_ref; }
+        case (ty::ty_native) { ret rs_none; }
+    }
+}
+
+//
+// Local Variables:
+// mode: rust
+// fill-column: 78;
+// indent-tabs-mode: nil
+// c-basic-offset: 4
+// buffer-file-coding-system: utf-8-unix
+// compile-command: "make -k -C $RBUILD 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
+// End:
+//

src/comp/middle/type_glue.rs

@@ -10,7 +10,7 @@ meta (name = "rustc",
 use std;
 
 mod middle {
-    mod shape;
+    mod type_glue;
     mod trans;
     mod ty;
     mod fold;