src/librustc/middle/trans/reflect.rs

   1 // Copyright 2012 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use back::link::mangle_internal_name_by_path_and_seq;
  12 use llvm::{ValueRef, get_param};
  13 use middle::trans::adt;
  14 use middle::trans::base::*;
  15 use middle::trans::build::*;
  16 use middle::trans::callee::ArgVals;
  17 use middle::trans::callee;
  18 use middle::trans::common::*;
  19 use middle::trans::datum::*;
  20 use middle::trans::glue;
  21 use middle::trans::machine;
  22 use middle::trans::meth;
  23 use middle::trans::type_::Type;
  24 use middle::trans::type_of::*;
  25 use middle::ty;
  26 use util::ppaux::ty_to_string;
  27
  28 use arena::TypedArena;
  29 use libc::c_uint;
  30 use syntax::ast::DefId;
  31 use syntax::ast;
  32 use syntax::ast_map;
  33 use syntax::parse::token::{InternedString, special_idents};
  34 use syntax::parse::token;
  35
  36 pub struct Reflector<'a, 'blk, 'tcx: 'blk> {
  37     visitor_val: ValueRef,
  38     visitor_items: &'a [ty::ImplOrTraitItem],
  39     final_bcx: Block<'blk, 'tcx>,
  40     tydesc_ty: Type,
  41     bcx: Block<'blk, 'tcx>
  42 }
  43
  44 impl<'a, 'blk, 'tcx> Reflector<'a, 'blk, 'tcx> {
  45     pub fn c_uint(&mut self, u: uint) -> ValueRef {
  46         C_uint(self.bcx.ccx(), u)
  47     }
  48
  49     pub fn c_bool(&mut self, b: bool) -> ValueRef {
  50         C_bool(self.bcx.ccx(), b)
  51     }
  52
  53     pub fn c_slice(&mut self, s: InternedString) -> ValueRef {
  54         // We're careful to not use first class aggregates here because that
  55         // will kick us off fast isel. (Issue #4352.)
  56         let bcx = self.bcx;
  57         let str_ty = ty::mk_str_slice(bcx.tcx(), ty::ReStatic, ast::MutImmutable);
  58         let scratch = rvalue_scratch_datum(bcx, str_ty, "");
  59         let len = C_uint(bcx.ccx(), s.get().len());
  60         let c_str = PointerCast(bcx, C_cstr(bcx.ccx(), s, false), Type::i8p(bcx.ccx()));
  61         Store(bcx, c_str, GEPi(bcx, scratch.val, [ 0, 0 ]));
  62         Store(bcx, len, GEPi(bcx, scratch.val, [ 0, 1 ]));
  63         scratch.val
  64     }
  65
  66     pub fn c_size_and_align(&mut self, t: ty::t) -> Vec<ValueRef> {
  67         let tr = type_of(self.bcx.ccx(), t);
  68         let s = machine::llsize_of_real(self.bcx.ccx(), tr);
  69         let a = align_of(self.bcx.ccx(), t);
  70         return vec!(self.c_uint(s as uint),
  71              self.c_uint(a as uint));
  72     }
  73
  74     pub fn c_tydesc(&mut self, t: ty::t) -> ValueRef {
  75         let bcx = self.bcx;
  76         let static_ti = get_tydesc(bcx.ccx(), t);
  77         glue::lazily_emit_visit_glue(bcx.ccx(), &*static_ti);
  78         PointerCast(bcx, static_ti.tydesc, self.tydesc_ty.ptr_to())
  79     }
  80
  81     pub fn c_mt(&mut self, mt: &ty::mt) -> Vec<ValueRef> {
  82         vec!(self.c_uint(mt.mutbl as uint),
  83           self.c_tydesc(mt.ty))
  84     }
  85
  86     pub fn visit(&mut self, ty_name: &str, args: &[ValueRef]) {
  87         let fcx = self.bcx.fcx;
  88         let tcx = self.bcx.tcx();
  89         let mth_idx = ty::impl_or_trait_item_idx(token::str_to_ident(format!(
  90                         "visit_{}", ty_name).as_slice()),
  91                                      self.visitor_items.as_slice()).expect(
  92                 format!("couldn't find visit method for {}", ty_name).as_slice());
  93         let method = match self.visitor_items[mth_idx] {
  94             ty::MethodTraitItem(ref method) => (*method).clone(),
  95         };
  96         let mth_ty = ty::mk_bare_fn(tcx, method.fty.clone());
  97         debug!("Emit call visit method: visit_{}: {}", ty_name, ty_to_string(tcx, mth_ty));
  98         let v = self.visitor_val;
  99         debug!("passing {} args:", args.len());
 100         let mut bcx = self.bcx;
 101         for (i, a) in args.iter().enumerate() {
 102             debug!("arg {}: {}", i, bcx.val_to_string(*a));
 103         }
 104         let result = unpack_result!(bcx, callee::trans_call_inner(
 105             self.bcx, None, mth_ty,
 106             |bcx, _| meth::trans_trait_callee_from_llval(bcx,
 107                                                          mth_ty,
 108                                                          mth_idx,
 109                                                          v),
 110             ArgVals(args), None));
 111         let next_bcx = fcx.new_temp_block("next");
 112         CondBr(bcx, result, next_bcx.llbb, self.final_bcx.llbb);
 113         self.bcx = next_bcx
 114     }
 115
 116     pub fn bracketed(&mut self,
 117                      bracket_name: &str,
 118                      extra: &[ValueRef],
 119                      inner: |&mut Reflector|) {
 120         self.visit(format!("enter_{}", bracket_name).as_slice(), extra);
 121         inner(self);
 122         self.visit(format!("leave_{}", bracket_name).as_slice(), extra);
 123     }
 124
 125     pub fn leaf(&mut self, name: &str) {
 126         self.visit(name, []);
 127     }
 128
 129     // Entrypoint
 130     pub fn visit_ty(&mut self, t: ty::t) {
 131         let bcx = self.bcx;
 132         let tcx = bcx.tcx();
 133         debug!("reflect::visit_ty {}", ty_to_string(bcx.tcx(), t));
 134
 135         match ty::get(t).sty {
 136           ty::ty_bot => self.leaf("bot"),
 137           ty::ty_nil => self.leaf("nil"),
 138           ty::ty_bool => self.leaf("bool"),
 139           ty::ty_char => self.leaf("char"),
 140           ty::ty_int(ast::TyI) => self.leaf("int"),
 141           ty::ty_int(ast::TyI8) => self.leaf("i8"),
 142           ty::ty_int(ast::TyI16) => self.leaf("i16"),
 143           ty::ty_int(ast::TyI32) => self.leaf("i32"),
 144           ty::ty_int(ast::TyI64) => self.leaf("i64"),
 145           ty::ty_uint(ast::TyU) => self.leaf("uint"),
 146           ty::ty_uint(ast::TyU8) => self.leaf("u8"),
 147           ty::ty_uint(ast::TyU16) => self.leaf("u16"),
 148           ty::ty_uint(ast::TyU32) => self.leaf("u32"),
 149           ty::ty_uint(ast::TyU64) => self.leaf("u64"),
 150           ty::ty_float(ast::TyF32) => self.leaf("f32"),
 151           ty::ty_float(ast::TyF64) => self.leaf("f64"),
 152
 153           ty::ty_open(_) | ty::ty_str | ty::ty_vec(_, None) | ty::ty_trait(..) => {
 154               // Unfortunately we can't do anything here because at runtime we
 155               // pass around the value by pointer (*u8). But unsized pointers are
 156               // fat and so we can't just cast them to *u8 and back. So we have
 157               // to work with the pointer directly (see ty_ptr/ty_rptr/ty_uniq).
 158               fail!("Can't reflect unsized type")
 159           }
 160           // FIXME(15049) Reflection for unsized structs.
 161           ty::ty_struct(..) if !ty::type_is_sized(bcx.tcx(), t) => {
 162               fail!("Can't reflect unsized type")
 163           }
 164
 165           // Should rename to vec_*.
 166           ty::ty_vec(ty, Some(sz)) => {
 167               let mut extra = (vec!(self.c_uint(sz))).append(self.c_size_and_align(t).as_slice());
 168               extra.push(self.c_tydesc(ty));
 169               self.visit("evec_fixed", extra.as_slice())
 170           }
 171           // Should remove mt from box and uniq.
 172           ty::ty_box(typ) => {
 173               let extra = self.c_mt(&ty::mt {
 174                   ty: typ,
 175                   mutbl: ast::MutImmutable,
 176               });
 177               self.visit("box", extra.as_slice())
 178           }
 179           ty::ty_ptr(ref mt) => {
 180               match ty::get(mt.ty).sty {
 181                   ty::ty_vec(ty, None) => {
 182                       let extra = self.c_mt(&ty::mt{ty: ty, mutbl: mt.mutbl});
 183                       self.visit("evec_slice", extra.as_slice())
 184                   }
 185                   ty::ty_str => self.visit("estr_slice", &[]),
 186                   ty::ty_trait(..) => {
 187                       let extra = [
 188                           self.c_slice(token::intern_and_get_ident(
 189                                   ty_to_string(tcx, t).as_slice()))
 190                       ];
 191                       self.visit("trait", extra);
 192                   }
 193                   _ => {
 194                       let extra = self.c_mt(mt);
 195                       self.visit("ptr", extra.as_slice())
 196                   }
 197               }
 198           }
 199           ty::ty_uniq(typ) => {
 200               match ty::get(typ).sty {
 201                   ty::ty_trait(..) => {
 202                       let extra = [
 203                           self.c_slice(token::intern_and_get_ident(
 204                                   ty_to_string(tcx, t).as_slice()))
 205                       ];
 206                       self.visit("trait", extra);
 207                   }
 208                   // FIXME(15049) allow reflection of Box<[T]>. You'll need to
 209                   // restore visit_evec_uniq.
 210                   ty::ty_vec(_, None) => {
 211                       fail!("Box<[T]> theoretically doesn't exist, so don't try to reflect it")
 212                   }
 213                   ty::ty_str => fail!("Can't reflect Box<str> which shouldn't be used anyway"),
 214                   _ => {
 215                       let extra = self.c_mt(&ty::mt {
 216                           ty: typ,
 217                           mutbl: ast::MutImmutable,
 218                       });
 219                       self.visit("uniq", extra.as_slice())
 220                   }
 221               }
 222           }
 223           ty::ty_rptr(_, ref mt) => {
 224               match ty::get(mt.ty).sty {
 225                   ty::ty_vec(ty, None) => {
 226                       let extra = self.c_mt(&ty::mt{ty: ty, mutbl: mt.mutbl});
 227                       self.visit("evec_slice", extra.as_slice())
 228                   }
 229                   ty::ty_str => self.visit("estr_slice", &[]),
 230                   ty::ty_trait(..) => {
 231                       let extra = [
 232                           self.c_slice(token::intern_and_get_ident(
 233                                   ty_to_string(tcx, t).as_slice()))
 234                       ];
 235                       self.visit("trait", extra);
 236                   }
 237                   _ => {
 238                       let extra = self.c_mt(mt);
 239                       self.visit("rptr", extra.as_slice())
 240                   }
 241               }
 242           }
 243
 244           ty::ty_tup(ref tys) => {
 245               let extra = (vec!(self.c_uint(tys.len())))
 246                           .append(self.c_size_and_align(t).as_slice());
 247               self.bracketed("tup", extra.as_slice(), |this| {
 248                   for (i, t) in tys.iter().enumerate() {
 249                       let extra = vec!(this.c_uint(i), this.c_tydesc(*t));
 250                       this.visit("tup_field", extra.as_slice());
 251                   }
 252               })
 253           }
 254
 255           // FIXME (#2594): fetch constants out of intrinsic
 256           // FIXME (#4809): visitor should break out bare fns from other fns
 257           ty::ty_closure(ref fty) => {
 258             let pureval = ast_fn_style_constant(fty.fn_style);
 259             let sigilval = match fty.store {
 260                 ty::UniqTraitStore => 2u,
 261                 ty::RegionTraitStore(..) => 4u,
 262             };
 263             let retval = if ty::type_is_bot(fty.sig.output) {0u} else {1u};
 264             let extra = vec!(self.c_uint(pureval),
 265                           self.c_uint(sigilval),
 266                           self.c_uint(fty.sig.inputs.len()),
 267                           self.c_uint(retval));
 268             self.visit("enter_fn", extra.as_slice());
 269             self.visit_sig(retval, &fty.sig);
 270             self.visit("leave_fn", extra.as_slice());
 271           }
 272
 273           // FIXME (#2594): fetch constants out of intrinsic:: for the
 274           // numbers.
 275           ty::ty_bare_fn(ref fty) => {
 276             let pureval = ast_fn_style_constant(fty.fn_style);
 277             let sigilval = 0u;
 278             let retval = if ty::type_is_bot(fty.sig.output) {0u} else {1u};
 279             let extra = vec!(self.c_uint(pureval),
 280                           self.c_uint(sigilval),
 281                           self.c_uint(fty.sig.inputs.len()),
 282                           self.c_uint(retval));
 283             self.visit("enter_fn", extra.as_slice());
 284             self.visit_sig(retval, &fty.sig);
 285             self.visit("leave_fn", extra.as_slice());
 286           }
 287
 288           ty::ty_struct(did, ref substs) => {
 289               let fields = ty::struct_fields(tcx, did, substs);
 290               let mut named_fields = false;
 291               if !fields.is_empty() {
 292                   named_fields = fields.get(0).ident.name !=
 293                       special_idents::unnamed_field.name;
 294               }
 295
 296               // This and the type_is_sized check on individual field types are
 297               // because we cannot reflect unsized types (see note above). We
 298               // just pretend the unsized field does not exist and print nothing.
 299               // This is sub-optimal.
 300               let len = fields.len();
 301
 302               let extra = (vec!(
 303                   self.c_slice(
 304                       token::intern_and_get_ident(ty_to_string(tcx,
 305                                                             t).as_slice())),
 306                   self.c_bool(named_fields),
 307                   self.c_uint(len)
 308               )).append(self.c_size_and_align(t).as_slice());
 309               self.bracketed("class", extra.as_slice(), |this| {
 310                   for (i, field) in fields.iter().enumerate() {
 311                       let extra = (vec!(
 312                         this.c_uint(i),
 313                         this.c_slice(token::get_ident(field.ident)),
 314                         this.c_bool(named_fields)
 315                       )).append(this.c_mt(&field.mt).as_slice());
 316                       this.visit("class_field", extra.as_slice());
 317                   }
 318               })
 319           }
 320
 321           // FIXME (#2595): visiting all the variants in turn is probably
 322           // not ideal. It'll work but will get costly on big enums. Maybe
 323           // let the visitor tell us if it wants to visit only a particular
 324           // variant?
 325           ty::ty_enum(did, ref substs) => {
 326             let ccx = bcx.ccx();
 327             let repr = adt::represent_type(bcx.ccx(), t);
 328             let variants = ty::substd_enum_variants(ccx.tcx(), did, substs);
 329             let llptrty = type_of(ccx, t).ptr_to();
 330             let opaquety = ty::get_opaque_ty(ccx.tcx()).unwrap();
 331             let opaqueptrty = ty::mk_ptr(ccx.tcx(), ty::mt { ty: opaquety,
 332                                                            mutbl: ast::MutImmutable });
 333
 334             let make_get_disr = || {
 335                 let sym = mangle_internal_name_by_path_and_seq(
 336                     ast_map::Values([].iter()).chain(None), "get_disr");
 337
 338                 let fn_ty = ty::mk_ctor_fn(ccx.tcx(), ast::DUMMY_NODE_ID,
 339                                            [opaqueptrty], ty::mk_u64());
 340                 let llfdecl = decl_internal_rust_fn(ccx,
 341                                                     fn_ty,
 342                                                     sym.as_slice());
 343                 let arena = TypedArena::new();
 344                 let empty_param_substs = param_substs::empty();
 345                 let fcx = new_fn_ctxt(ccx, llfdecl, ast::DUMMY_NODE_ID, false,
 346                                       ty::mk_u64(), &empty_param_substs,
 347                                       None, &arena);
 348                 let bcx = init_function(&fcx, false, ty::mk_u64());
 349
 350                 // we know the return type of llfdecl is an int here, so
 351                 // no need for a special check to see if the return type
 352                 // is immediate.
 353                 let arg = get_param(llfdecl, fcx.arg_pos(0u) as c_uint);
 354                 let arg = BitCast(bcx, arg, llptrty);
 355                 let ret = adt::trans_get_discr(bcx, &*repr, arg, Some(Type::i64(ccx)));
 356                 assert!(!fcx.needs_ret_allocas);
 357                 let ret_slot = fcx.get_ret_slot(bcx, ty::mk_u64(), "ret_slot");
 358                 Store(bcx, ret, ret_slot);
 359                 match fcx.llreturn.get() {
 360                     Some(llreturn) => Br(bcx, llreturn),
 361                     None => {}
 362                 };
 363                 finish_fn(&fcx, bcx, ty::mk_u64());
 364                 llfdecl
 365             };
 366
 367             let enum_args = (vec!(self.c_uint(variants.len()), make_get_disr()))
 368                             .append(self.c_size_and_align(t).as_slice());
 369             self.bracketed("enum", enum_args.as_slice(), |this| {
 370                 for (i, v) in variants.iter().enumerate() {
 371                     let name = token::get_ident(v.name);
 372                     let variant_args = [this.c_uint(i),
 373                                          C_u64(ccx, v.disr_val),
 374                                          this.c_uint(v.args.len()),
 375                                          this.c_slice(name)];
 376                     this.bracketed("enum_variant",
 377                                    variant_args,
 378                                    |this| {
 379                         for (j, a) in v.args.iter().enumerate() {
 380                             let bcx = this.bcx;
 381                             let null = C_null(llptrty);
 382                             let ptr = adt::trans_field_ptr(bcx, &*repr, null, v.disr_val, j);
 383                             let offset = p2i(ccx, ptr);
 384                             let field_args = [this.c_uint(j),
 385                                                offset,
 386                                                this.c_tydesc(*a)];
 387                             this.visit("enum_variant_field",
 388                                        field_args);
 389                         }
 390                     })
 391                 }
 392             })
 393           }
 394
 395           // Miscellaneous extra types
 396           ty::ty_infer(_) => self.leaf("infer"),
 397           ty::ty_err => self.leaf("err"),
 398           ty::ty_unboxed_closure(..) => self.leaf("err"),
 399           ty::ty_param(ref p) => {
 400               let extra = vec!(self.c_uint(p.idx));
 401               self.visit("param", extra.as_slice())
 402           }
 403         }
 404     }
 405
 406     pub fn visit_sig(&mut self, retval: uint, sig: &ty::FnSig) {
 407         for (i, arg) in sig.inputs.iter().enumerate() {
 408             let modeval = 5u;   // "by copy"
 409             let extra = vec!(self.c_uint(i),
 410                          self.c_uint(modeval),
 411                          self.c_tydesc(*arg));
 412             self.visit("fn_input", extra.as_slice());
 413         }
 414         let extra = vec!(self.c_uint(retval),
 415                       self.c_bool(sig.variadic),
 416                       self.c_tydesc(sig.output));
 417         self.visit("fn_output", extra.as_slice());
 418     }
 419 }
 420
 421 // Emit a sequence of calls to visit_ty::visit_foo
 422 pub fn emit_calls_to_trait_visit_ty<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
 423                                                 t: ty::t,
 424                                                 visitor_val: ValueRef,
 425                                                 visitor_trait_id: DefId)
 426                                                 -> Block<'blk, 'tcx> {
 427     let fcx = bcx.fcx;
 428     let final = fcx.new_temp_block("final");
 429     let tydesc_ty = ty::get_tydesc_ty(bcx.tcx()).unwrap();
 430     let tydesc_ty = type_of(bcx.ccx(), tydesc_ty);
 431     let visitor_items = ty::trait_items(bcx.tcx(), visitor_trait_id);
 432     let mut r = Reflector {
 433         visitor_val: visitor_val,
 434         visitor_items: visitor_items.as_slice(),
 435         final_bcx: final,
 436         tydesc_ty: tydesc_ty,
 437         bcx: bcx
 438     };
 439     r.visit_ty(t);
 440     Br(r.bcx, final.llbb);
 441     return final;
 442 }
 443
 444 pub fn ast_fn_style_constant(fn_style: ast::FnStyle) -> uint {
 445     match fn_style {
 446         ast::UnsafeFn => 1u,
 447         ast::NormalFn => 2u,
 448     }
 449 }