src/interpreter.rs

   1 use arena::TypedArena;
   2 use rustc::infer;
   3 use rustc::middle::const_eval;
   4 use rustc::middle::def_id::DefId;
   5 use rustc::mir::mir_map::MirMap;
   6 use rustc::mir::repr as mir;
   7 use rustc::traits::{self, ProjectionMode};
   8 use rustc::ty::fold::TypeFoldable;
   9 use rustc::ty::subst::{self, Subst, Substs};
  10 use rustc::ty::{self, TyCtxt};
  11 use rustc::util::nodemap::DefIdMap;
  12 use rustc_data_structures::fnv::FnvHashMap;
  13 use std::cell::RefCell;
  14 use std::iter;
  15 use std::ops::Deref;
  16 use std::rc::Rc;
  17 use syntax::ast;
  18 use syntax::attr;
  19 use syntax::codemap::{self, DUMMY_SP};
  20
  21 use error::{EvalError, EvalResult};
  22 use memory::{self, FieldRepr, Memory, Pointer, Repr};
  23 use primval::{self, PrimVal};
  24
  25 const TRACE_EXECUTION: bool = false;
  26
  27 struct Interpreter<'a, 'tcx: 'a, 'arena> {
  28     /// The results of the type checker, from rustc.
  29     tcx: &'a TyCtxt<'tcx>,
  30
  31     /// A mapping from NodeIds to Mir, from rustc. Only contains MIR for crate-local items.
  32     mir_map: &'a MirMap<'tcx>,
  33
  34     /// A local cache from DefIds to Mir for non-crate-local items.
  35     mir_cache: RefCell<DefIdMap<Rc<mir::Mir<'tcx>>>>,
  36
  37     /// An arena allocator for type representations.
  38     repr_arena: &'arena TypedArena<Repr>,
  39
  40     /// A cache for in-memory representations of types.
  41     repr_cache: RefCell<FnvHashMap<ty::Ty<'tcx>, &'arena Repr>>,
  42
  43     /// The virtual memory system.
  44     memory: Memory,
  45
  46     /// The virtual call stack.
  47     stack: Vec<Frame<'a, 'tcx>>,
  48
  49     /// Another stack containing the type substitutions for the current function invocation. It
  50     /// exists separately from `stack` because it must contain the `Substs` for a function while
  51     /// *creating* the `Frame` for that same function.
  52     substs_stack: Vec<&'tcx Substs<'tcx>>,
  53 }
  54
  55 /// A stack frame.
  56 struct Frame<'a, 'tcx: 'a> {
  57     /// The MIR for the function called on this frame.
  58     mir: CachedMir<'a, 'tcx>,
  59
  60     /// The block this frame will execute when a function call returns back to this frame.
  61     next_block: mir::BasicBlock,
  62
  63     /// A pointer for writing the return value of the current call if it's not a diverging call.
  64     return_ptr: Option<Pointer>,
  65
  66     /// The list of locals for the current function, stored in order as
  67     /// `[arguments..., variables..., temporaries...]`. The variables begin at `self.var_offset`
  68     /// and the temporaries at `self.temp_offset`.
  69     locals: Vec<Pointer>,
  70
  71     /// The offset of the first variable in `self.locals`.
  72     var_offset: usize,
  73
  74     /// The offset of the first temporary in `self.locals`.
  75     temp_offset: usize,
  76 }
  77
  78 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
  79 struct Lvalue {
  80     ptr: Pointer,
  81     extra: LvalueExtra,
  82 }
  83
  84 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
  85 enum LvalueExtra {
  86     None,
  87     Length(u64),
  88     // Vtable(memory::AllocId),
  89 }
  90
  91 #[derive(Clone)]
  92 enum CachedMir<'mir, 'tcx: 'mir> {
  93     Ref(&'mir mir::Mir<'tcx>),
  94     Owned(Rc<mir::Mir<'tcx>>)
  95 }
  96
  97 /// Represents the action to be taken in the main loop as a result of executing a terminator.
  98 enum TerminatorTarget {
  99     /// Make a local jump to the given block.
 100     Block(mir::BasicBlock),
 101
 102     /// Start executing from the new current frame. (For function calls.)
 103     Call,
 104
 105     /// Stop executing the current frame and resume the previous frame.
 106     Return,
 107 }
 108
 109 impl<'a, 'tcx: 'a, 'arena> Interpreter<'a, 'tcx, 'arena> {
 110     fn new(tcx: &'a TyCtxt<'tcx>, mir_map: &'a MirMap<'tcx>, repr_arena: &'arena TypedArena<Repr>)
 111         -> Self
 112     {
 113         Interpreter {
 114             tcx: tcx,
 115             mir_map: mir_map,
 116             mir_cache: RefCell::new(DefIdMap()),
 117             repr_arena: repr_arena,
 118             repr_cache: RefCell::new(FnvHashMap()),
 119             memory: Memory::new(),
 120             stack: Vec::new(),
 121             substs_stack: Vec::new(),
 122         }
 123     }
 124
 125     fn maybe_report<T>(&self, span: codemap::Span, r: EvalResult<T>) -> EvalResult<T> {
 126         if let Err(ref e) = r {
 127             let mut err = self.tcx.sess.struct_span_err(span, &e.to_string());
 128             err.emit();
 129         }
 130         r
 131     }
 132
 133     fn run(&mut self) -> EvalResult<()> {
 134         use std::fmt::Debug;
 135         fn print_trace<T: Debug>(t: &T, suffix: &'static str, indent: usize) {
 136             if !TRACE_EXECUTION { return; }
 137             for _ in 0..indent { print!("  "); }
 138             println!("{:?}{}", t, suffix);
 139         }
 140
 141         'outer: while !self.stack.is_empty() {
 142             let mut current_block = self.frame().next_block;
 143
 144             loop {
 145                 print_trace(&current_block, ":", self.stack.len());
 146                 let current_mir = self.mir().clone(); // Cloning a reference.
 147                 let block_data = current_mir.basic_block_data(current_block);
 148
 149                 for stmt in &block_data.statements {
 150                     print_trace(stmt, "", self.stack.len() + 1);
 151                     let mir::StatementKind::Assign(ref lvalue, ref rvalue) = stmt.kind;
 152                     let result = self.eval_assignment(lvalue, rvalue);
 153                     try!(self.maybe_report(stmt.span, result));
 154                 }
 155
 156                 let terminator = block_data.terminator();
 157                 print_trace(terminator, "", self.stack.len() + 1);
 158
 159                 let result = self.eval_terminator(terminator);
 160                 match try!(self.maybe_report(terminator.span, result)) {
 161                     TerminatorTarget::Block(block) => current_block = block,
 162                     TerminatorTarget::Return => {
 163                         self.pop_stack_frame();
 164                         self.substs_stack.pop();
 165                         continue 'outer;
 166                     }
 167                     TerminatorTarget::Call => continue 'outer,
 168                 }
 169             }
 170         }
 171
 172         Ok(())
 173     }
 174
 175     fn push_stack_frame(&mut self, mir: CachedMir<'a, 'tcx>, return_ptr: Option<Pointer>) {
 176         let arg_tys = mir.arg_decls.iter().map(|a| a.ty);
 177         let var_tys = mir.var_decls.iter().map(|v| v.ty);
 178         let temp_tys = mir.temp_decls.iter().map(|t| t.ty);
 179
 180         let locals: Vec<Pointer> = arg_tys.chain(var_tys).chain(temp_tys).map(|ty| {
 181             let size = self.ty_size(ty);
 182             self.memory.allocate(size)
 183         }).collect();
 184
 185         let num_args = mir.arg_decls.len();
 186         let num_vars = mir.var_decls.len();
 187
 188         self.stack.push(Frame {
 189             mir: mir.clone(),
 190             next_block: mir::START_BLOCK,
 191             return_ptr: return_ptr,
 192             locals: locals,
 193             var_offset: num_args,
 194             temp_offset: num_args + num_vars,
 195         });
 196     }
 197
 198     fn pop_stack_frame(&mut self) {
 199         let _frame = self.stack.pop().expect("tried to pop a stack frame, but there were none");
 200         // TODO(tsion): Deallocate local variables.
 201     }
 202
 203     fn eval_terminator(&mut self, terminator: &mir::Terminator<'tcx>)
 204             -> EvalResult<TerminatorTarget> {
 205         use rustc::mir::repr::TerminatorKind::*;
 206         let target = match terminator.kind {
 207             Return => TerminatorTarget::Return,
 208
 209             Goto { target } => TerminatorTarget::Block(target),
 210
 211             If { ref cond, targets: (then_target, else_target) } => {
 212                 let cond_ptr = try!(self.eval_operand(cond));
 213                 let cond_val = try!(self.memory.read_bool(cond_ptr));
 214                 TerminatorTarget::Block(if cond_val { then_target } else { else_target })
 215             }
 216
 217             SwitchInt { ref discr, ref values, ref targets, .. } => {
 218                 let discr_ptr = try!(self.eval_lvalue(discr)).to_ptr();
 219                 let discr_size = self.lvalue_repr(discr).size();
 220                 let discr_val = try!(self.memory.read_uint(discr_ptr, discr_size));
 221
 222                 // Branch to the `otherwise` case by default, if no match is found.
 223                 let mut target_block = targets[targets.len() - 1];
 224
 225                 for (index, val_const) in values.iter().enumerate() {
 226                     let ptr = try!(self.const_to_ptr(val_const));
 227                     let val = try!(self.memory.read_uint(ptr, discr_size));
 228                     if discr_val == val {
 229                         target_block = targets[index];
 230                         break;
 231                     }
 232                 }
 233
 234                 TerminatorTarget::Block(target_block)
 235             }
 236
 237             Switch { ref discr, ref targets, adt_def } => {
 238                 let adt_ptr = try!(self.eval_lvalue(discr)).to_ptr();
 239                 let adt_repr = self.lvalue_repr(discr);
 240                 let discr_size = match *adt_repr {
 241                     Repr::Aggregate { discr_size, .. } => discr_size,
 242                     _ => panic!("attmpted to switch on non-aggregate type"),
 243                 };
 244                 let discr_val = try!(self.memory.read_uint(adt_ptr, discr_size));
 245
 246                 let matching = adt_def.variants.iter()
 247                     .position(|v| discr_val == v.disr_val.to_u64_unchecked());
 248
 249                 match matching {
 250                     Some(i) => TerminatorTarget::Block(targets[i]),
 251                     None => return Err(EvalError::InvalidDiscriminant),
 252                 }
 253             }
 254
 255             Call { ref func, ref args, ref destination, .. } => {
 256                 let mut return_ptr = None;
 257                 if let Some((ref lv, target)) = *destination {
 258                     self.frame_mut().next_block = target;
 259                     return_ptr = Some(try!(self.eval_lvalue(lv)).to_ptr());
 260                 }
 261
 262                 let func_ty = self.operand_ty(func);
 263                 match func_ty.sty {
 264                     ty::TyFnDef(def_id, substs, fn_ty) => {
 265                         use syntax::abi::Abi;
 266                         match fn_ty.abi {
 267                             Abi::RustIntrinsic => {
 268                                 let name = self.tcx.item_name(def_id).as_str();
 269                                 match fn_ty.sig.0.output {
 270                                     ty::FnConverging(ty) => {
 271                                         let size = self.ty_size(ty);
 272                                         try!(self.call_intrinsic(&name, substs, args,
 273                                             return_ptr.unwrap(), size))
 274                                     }
 275                                     ty::FnDiverging => unimplemented!(),
 276                                 }
 277                             }
 278
 279                             Abi::C =>
 280                                 try!(self.call_c_abi(def_id, args, return_ptr.unwrap())),
 281
 282                             Abi::Rust | Abi::RustCall => {
 283                                 // TODO(tsion): Adjust the first argument when calling a Fn or
 284                                 // FnMut closure via FnOnce::call_once.
 285
 286                                 // Only trait methods can have a Self parameter.
 287                                 let (def_id, substs) = if substs.self_ty().is_some() {
 288                                     self.trait_method(def_id, substs)
 289                                 } else {
 290                                     (def_id, substs)
 291                                 };
 292
 293                                 let mut arg_srcs = Vec::new();
 294                                 for arg in args {
 295                                     let (src, repr) = try!(self.eval_operand_and_repr(arg));
 296                                     arg_srcs.push((src, repr.size()));
 297                                 }
 298
 299                                 if fn_ty.abi == Abi::RustCall && !args.is_empty() {
 300                                     arg_srcs.pop();
 301                                     let last_arg = args.last().unwrap();
 302                                     let (last_src, last_repr) =
 303                                         try!(self.eval_operand_and_repr(last_arg));
 304                                     match *last_repr {
 305                                         Repr::Aggregate { discr_size: 0, ref variants, .. } => {
 306                                             assert_eq!(variants.len(), 1);
 307                                             for field in &variants[0] {
 308                                                 let src = last_src.offset(field.offset as isize);
 309                                                 arg_srcs.push((src, field.size));
 310                                             }
 311                                         }
 312
 313                                         _ => panic!("expected tuple as last argument in function with 'rust-call' ABI"),
 314                                     }
 315                                 }
 316
 317                                 let mir = self.load_mir(def_id);
 318                                 self.substs_stack.push(substs);
 319                                 self.push_stack_frame(mir, return_ptr);
 320
 321                                 for (i, (src, size)) in arg_srcs.into_iter().enumerate() {
 322                                     let dest = self.frame().locals[i];
 323                                     try!(self.memory.copy(src, dest, size));
 324                                 }
 325
 326                                 TerminatorTarget::Call
 327                             }
 328
 329                             abi => panic!("can't handle function with {:?} ABI", abi),
 330                         }
 331                     }
 332
 333                     _ => panic!("can't handle callee of type {:?}", func_ty),
 334                 }
 335             }
 336
 337             Drop { target, .. } => {
 338                 // TODO: Handle destructors and dynamic drop.
 339                 TerminatorTarget::Block(target)
 340             }
 341
 342             Resume => unimplemented!(),
 343         };
 344
 345         Ok(target)
 346     }
 347
 348     fn call_intrinsic(&mut self, name: &str, substs: &'tcx Substs<'tcx>,
 349         args: &[mir::Operand<'tcx>], dest: Pointer, dest_size: usize)
 350         -> EvalResult<TerminatorTarget>
 351     {
 352         match name {
 353             "assume" => {}
 354
 355             "copy_nonoverlapping" => {
 356                 let elem_ty = *substs.types.get(subst::FnSpace, 0);
 357                 let elem_size = self.ty_size(elem_ty);
 358
 359                 let src_arg   = try!(self.eval_operand(&args[0]));
 360                 let dest_arg  = try!(self.eval_operand(&args[1]));
 361                 let count_arg = try!(self.eval_operand(&args[2]));
 362
 363                 let src   = try!(self.memory.read_ptr(src_arg));
 364                 let dest  = try!(self.memory.read_ptr(dest_arg));
 365                 let count = try!(self.memory.read_isize(count_arg));
 366
 367                 try!(self.memory.copy(src, dest, count as usize * elem_size));
 368             }
 369
 370             // TODO(tsion): Mark as dropped?
 371             "forget" => {}
 372
 373             "min_align_of" => {
 374                 try!(self.memory.write_int(dest, 1, dest_size));
 375             }
 376
 377             "move_val_init" => {
 378                 let ty = *substs.types.get(subst::FnSpace, 0);
 379                 let size = self.ty_size(ty);
 380
 381                 let ptr_arg = try!(self.eval_operand(&args[0]));
 382                 let ptr = try!(self.memory.read_ptr(ptr_arg));
 383
 384                 let val = try!(self.eval_operand(&args[1]));
 385                 try!(self.memory.copy(val, ptr, size));
 386             }
 387
 388             // FIXME(tsion): Handle different integer types correctly.
 389             "mul_with_overflow" => {
 390                 let ty = *substs.types.get(subst::FnSpace, 0);
 391                 let size = self.ty_size(ty);
 392
 393                 let left_arg  = try!(self.eval_operand(&args[0]));
 394                 let right_arg = try!(self.eval_operand(&args[1]));
 395
 396                 let left = try!(self.memory.read_int(left_arg, size));
 397                 let right = try!(self.memory.read_int(right_arg, size));
 398
 399                 let (n, overflowed) = unsafe {
 400                     ::std::intrinsics::mul_with_overflow::<i64>(left, right)
 401                 };
 402
 403                 try!(self.memory.write_int(dest, n, size));
 404                 try!(self.memory.write_bool(dest.offset(size as isize), overflowed));
 405             }
 406
 407             "offset" => {
 408                 let pointee_ty = *substs.types.get(subst::FnSpace, 0);
 409                 let pointee_size = self.ty_size(pointee_ty) as isize;
 410
 411                 let ptr_arg    = try!(self.eval_operand(&args[0]));
 412                 let offset_arg = try!(self.eval_operand(&args[1]));
 413
 414                 let offset = try!(self.memory.read_isize(offset_arg));
 415
 416                 match self.memory.read_ptr(ptr_arg) {
 417                     Ok(ptr) => {
 418                         let result_ptr = ptr.offset(offset as isize * pointee_size);
 419                         try!(self.memory.write_ptr(dest, result_ptr));
 420                     }
 421                     Err(EvalError::ReadBytesAsPointer) => {
 422                         let addr = try!(self.memory.read_isize(ptr_arg));
 423                         let result_addr = addr + offset * pointee_size as i64;
 424                         try!(self.memory.write_isize(dest, result_addr));
 425                     }
 426                     Err(e) => return Err(e),
 427                 }
 428             }
 429
 430             // FIXME(tsion): Handle different integer types correctly. Use primvals?
 431             "overflowing_sub" => {
 432                 let ty = *substs.types.get(subst::FnSpace, 0);
 433                 let size = self.ty_size(ty);
 434
 435                 let left_arg  = try!(self.eval_operand(&args[0]));
 436                 let right_arg = try!(self.eval_operand(&args[1]));
 437
 438                 let left = try!(self.memory.read_int(left_arg, size));
 439                 let right = try!(self.memory.read_int(right_arg, size));
 440
 441                 let n = left.wrapping_sub(right);
 442                 try!(self.memory.write_int(dest, n, size));
 443             }
 444
 445             "size_of" => {
 446                 let ty = *substs.types.get(subst::FnSpace, 0);
 447                 let size = self.ty_size(ty) as u64;
 448                 try!(self.memory.write_uint(dest, size, dest_size));
 449             }
 450
 451             "transmute" => {
 452                 let src = try!(self.eval_operand(&args[0]));
 453                 try!(self.memory.copy(src, dest, dest_size));
 454             }
 455
 456             "uninit" => {
 457                 try!(self.memory.mark_definedness(dest, dest_size, false));
 458             }
 459
 460             name => panic!("can't handle intrinsic: {}", name),
 461         }
 462
 463         // Since we pushed no stack frame, the main loop will act
 464         // as if the call just completed and it's returning to the
 465         // current frame.
 466         Ok(TerminatorTarget::Call)
 467     }
 468
 469     fn call_c_abi(&mut self, def_id: DefId, args: &[mir::Operand<'tcx>], dest: Pointer)
 470         -> EvalResult<TerminatorTarget>
 471     {
 472         let name = self.tcx.item_name(def_id);
 473         let attrs = self.tcx.get_attrs(def_id);
 474         let link_name = match attr::first_attr_value_str_by_name(&attrs, "link_name") {
 475             Some(ln) => ln.clone(),
 476             None => name.as_str(),
 477         };
 478
 479         match &link_name[..] {
 480             "__rust_allocate" => {
 481                 let size_arg  = try!(self.eval_operand(&args[0]));
 482                 let _align_arg = try!(self.eval_operand(&args[1]));
 483                 let size = try!(self.memory.read_usize(size_arg));
 484                 let ptr = self.memory.allocate(size as usize);
 485                 try!(self.memory.write_ptr(dest, ptr));
 486             }
 487
 488             _ => panic!("can't call C ABI function: {}", link_name),
 489         }
 490
 491         // Since we pushed no stack frame, the main loop will act
 492         // as if the call just completed and it's returning to the
 493         // current frame.
 494         Ok(TerminatorTarget::Call)
 495     }
 496
 497     fn assign_to_aggregate(
 498         &mut self,
 499         dest: Pointer,
 500         dest_repr: &Repr,
 501         variant: usize,
 502         discr: Option<u64>,
 503         operands: &[mir::Operand<'tcx>],
 504     ) -> EvalResult<()> {
 505         match *dest_repr {
 506             Repr::Aggregate { discr_size, ref variants, .. } => {
 507                 if discr_size > 0 {
 508                     try!(self.memory.write_uint(dest, discr.unwrap(), discr_size));
 509                 }
 510                 let after_discr = dest.offset(discr_size as isize);
 511                 for (field, operand) in variants[variant].iter().zip(operands) {
 512                     let src = try!(self.eval_operand(operand));
 513                     let field_dest = after_discr.offset(field.offset as isize);
 514                     try!(self.memory.copy(src, field_dest, field.size));
 515                 }
 516             }
 517             _ => panic!("expected Repr::Aggregate target"),
 518         }
 519         Ok(())
 520     }
 521
 522     fn eval_assignment(&mut self, lvalue: &mir::Lvalue<'tcx>, rvalue: &mir::Rvalue<'tcx>)
 523         -> EvalResult<()>
 524     {
 525         let dest = try!(self.eval_lvalue(lvalue)).to_ptr();
 526         let dest_repr = self.lvalue_repr(lvalue);
 527
 528         use rustc::mir::repr::Rvalue::*;
 529         match *rvalue {
 530             Use(ref operand) => {
 531                 let src = try!(self.eval_operand(operand));
 532                 try!(self.memory.copy(src, dest, dest_repr.size()));
 533             }
 534
 535             BinaryOp(bin_op, ref left, ref right) => {
 536                 let left_ptr = try!(self.eval_operand(left));
 537                 let left_ty = self.operand_ty(left);
 538                 let left_val = try!(self.read_primval(left_ptr, left_ty));
 539
 540                 let right_ptr = try!(self.eval_operand(right));
 541                 let right_ty = self.operand_ty(right);
 542                 let right_val = try!(self.read_primval(right_ptr, right_ty));
 543
 544                 let val = try!(primval::binary_op(bin_op, left_val, right_val));
 545                 try!(self.memory.write_primval(dest, val));
 546             }
 547
 548             UnaryOp(un_op, ref operand) => {
 549                 let ptr = try!(self.eval_operand(operand));
 550                 let ty = self.operand_ty(operand);
 551                 let val = try!(self.read_primval(ptr, ty));
 552                 try!(self.memory.write_primval(dest, primval::unary_op(un_op, val)));
 553             }
 554
 555             Aggregate(ref kind, ref operands) => {
 556                 use rustc::mir::repr::AggregateKind::*;
 557                 match *kind {
 558                     Tuple | Closure(..) =>
 559                         try!(self.assign_to_aggregate(dest, &dest_repr, 0, None, operands)),
 560
 561                     Adt(adt_def, variant, _) => {
 562                         let discr = Some(adt_def.variants[variant].disr_val.to_u64_unchecked());
 563                         try!(self.assign_to_aggregate(dest, &dest_repr, variant, discr, operands));
 564                     }
 565
 566                     Vec => if let Repr::Array { elem_size, length } = *dest_repr {
 567                         assert_eq!(length, operands.len());
 568                         for (i, operand) in operands.iter().enumerate() {
 569                             let src = try!(self.eval_operand(operand));
 570                             let elem_dest = dest.offset((i * elem_size) as isize);
 571                             try!(self.memory.copy(src, elem_dest, elem_size));
 572                         }
 573                     } else {
 574                         panic!("expected Repr::Array target");
 575                     },
 576                 }
 577             }
 578
 579             Repeat(ref operand, _) => {
 580                 if let Repr::Array { elem_size, length } = *dest_repr {
 581                     let src = try!(self.eval_operand(operand));
 582                     for i in 0..length {
 583                         let elem_dest = dest.offset((i * elem_size) as isize);
 584                         try!(self.memory.copy(src, elem_dest, elem_size));
 585                     }
 586                 } else {
 587                     panic!("expected Repr::Array target");
 588                 }
 589             }
 590
 591             Len(ref lvalue) => {
 592                 let src = try!(self.eval_lvalue(lvalue));
 593                 let ty = self.lvalue_ty(lvalue);
 594                 let len = match ty.sty {
 595                     ty::TyArray(_, n) => n as u64,
 596                     ty::TySlice(_) => if let LvalueExtra::Length(n) = src.extra {
 597                         n
 598                     } else {
 599                         panic!("Rvalue::Len of a slice given non-slice pointer: {:?}", src);
 600                     },
 601                     _ => panic!("Rvalue::Len expected array or slice, got {:?}", ty),
 602                 };
 603                 try!(self.memory.write_usize(dest, len));
 604             }
 605
 606             Ref(_, _, ref lvalue) => {
 607                 let lv = try!(self.eval_lvalue(lvalue));
 608                 try!(self.memory.write_ptr(dest, lv.ptr));
 609                 match lv.extra {
 610                     LvalueExtra::None => {},
 611                     LvalueExtra::Length(len) => {
 612                         let len_ptr = dest.offset(self.memory.pointer_size as isize);
 613                         try!(self.memory.write_usize(len_ptr, len));
 614                     }
 615                 }
 616             }
 617
 618             Box(ty) => {
 619                 let size = self.ty_size(ty);
 620                 let ptr = self.memory.allocate(size);
 621                 try!(self.memory.write_ptr(dest, ptr));
 622             }
 623
 624             Cast(kind, ref operand, dest_ty) => {
 625                 let src = try!(self.eval_operand(operand));
 626                 let src_ty = self.operand_ty(operand);
 627
 628                 use rustc::mir::repr::CastKind::*;
 629                 match kind {
 630                     Unsize => {
 631                         try!(self.memory.copy(src, dest, 8));
 632                         let src_pointee_ty = pointee_type(src_ty).unwrap();
 633                         let dest_pointee_ty = pointee_type(dest_ty).unwrap();
 634
 635                         match (&src_pointee_ty.sty, &dest_pointee_ty.sty) {
 636                             (&ty::TyArray(_, length), &ty::TySlice(_)) => {
 637                                 let len_ptr = dest.offset(self.memory.pointer_size as isize);
 638                                 try!(self.memory.write_usize(len_ptr, length as u64));
 639                             }
 640
 641                             _ => panic!("can't handle cast: {:?}", rvalue),
 642                         }
 643                     }
 644
 645                     Misc => {
 646                         // FIXME(tsion): Wrong for almost everything.
 647                         let size = dest_repr.size();
 648                         try!(self.memory.copy(src, dest, size));
 649                     }
 650
 651                     _ => panic!("can't handle cast: {:?}", rvalue),
 652                 }
 653             }
 654
 655             Slice { .. } => unimplemented!(),
 656             InlineAsm { .. } => unimplemented!(),
 657         }
 658
 659         Ok(())
 660     }
 661
 662     fn eval_operand(&mut self, op: &mir::Operand<'tcx>) -> EvalResult<Pointer> {
 663         self.eval_operand_and_repr(op).map(|(p, _)| p)
 664     }
 665
 666     fn eval_operand_and_repr(&mut self, op: &mir::Operand<'tcx>)
 667         -> EvalResult<(Pointer, &'arena Repr)>
 668     {
 669         use rustc::mir::repr::Operand::*;
 670         match *op {
 671             Consume(ref lvalue) =>
 672                 Ok((try!(self.eval_lvalue(lvalue)).to_ptr(), self.lvalue_repr(lvalue))),
 673             Constant(mir::Constant { ref literal, ty, .. }) => {
 674                 use rustc::mir::repr::Literal::*;
 675                 match *literal {
 676                     Value { ref value } => Ok((
 677                         try!(self.const_to_ptr(value)),
 678                         self.ty_to_repr(ty),
 679                     )),
 680                     Item { .. } => unimplemented!(),
 681                 }
 682             }
 683         }
 684     }
 685
 686     // TODO(tsion): Replace this inefficient hack with a wrapper like LvalueTy (e.g. LvalueRepr).
 687     fn lvalue_repr(&self, lvalue: &mir::Lvalue<'tcx>) -> &'arena Repr {
 688         use rustc::mir::tcx::LvalueTy;
 689         match self.mir().lvalue_ty(self.tcx, lvalue) {
 690             LvalueTy::Ty { ty } => self.ty_to_repr(ty),
 691             LvalueTy::Downcast { adt_def, substs, variant_index } => {
 692                 let field_tys = adt_def.variants[variant_index].fields.iter()
 693                     .map(|f| f.ty(self.tcx, substs));
 694                 self.repr_arena.alloc(self.make_aggregate_repr(iter::once(field_tys)))
 695             }
 696         }
 697     }
 698
 699     fn eval_lvalue(&mut self, lvalue: &mir::Lvalue<'tcx>) -> EvalResult<Lvalue> {
 700         use rustc::mir::repr::Lvalue::*;
 701         let ptr = match *lvalue {
 702             ReturnPointer => self.frame().return_ptr
 703                 .expect("ReturnPointer used in a function with no return value"),
 704             Arg(i) => self.frame().locals[i as usize],
 705             Var(i) => self.frame().locals[self.frame().var_offset + i as usize],
 706             Temp(i) => self.frame().locals[self.frame().temp_offset + i as usize],
 707
 708             Static(_def_id) => unimplemented!(),
 709
 710             Projection(ref proj) => {
 711                 let base_ptr = try!(self.eval_lvalue(&proj.base)).to_ptr();
 712                 let base_repr = self.lvalue_repr(&proj.base);
 713                 let base_ty = self.lvalue_ty(&proj.base);
 714                 use rustc::mir::repr::ProjectionElem::*;
 715                 match proj.elem {
 716                     Field(field, _) => match *base_repr {
 717                         Repr::Aggregate { discr_size: 0, ref variants, .. } => {
 718                             let fields = &variants[0];
 719                             base_ptr.offset(fields[field.index()].offset as isize)
 720                         }
 721                         _ => panic!("field access on non-product type: {:?}", base_repr),
 722                     },
 723
 724                     Downcast(..) => match *base_repr {
 725                         Repr::Aggregate { discr_size, .. } => base_ptr.offset(discr_size as isize),
 726                         _ => panic!("variant downcast on non-aggregate type: {:?}", base_repr),
 727                     },
 728
 729                     Deref => {
 730                         let pointee_ty = pointee_type(base_ty).expect("Deref of non-pointer");
 731                         let ptr = try!(self.memory.read_ptr(base_ptr));
 732                         let extra = match pointee_ty.sty {
 733                             ty::TySlice(_) | ty::TyStr => {
 734                                 let len_ptr = base_ptr.offset(self.memory.pointer_size as isize);
 735                                 let len = try!(self.memory.read_usize(len_ptr));
 736                                 LvalueExtra::Length(len)
 737                             }
 738                             ty::TyTrait(_) => unimplemented!(),
 739                             _ => LvalueExtra::None,
 740                         };
 741                         return Ok(Lvalue { ptr: ptr, extra: extra });
 742                     }
 743
 744                     Index(ref operand) => {
 745                         let elem_size = match base_ty.sty {
 746                             ty::TyArray(elem_ty, _) => self.ty_size(elem_ty),
 747                             ty::TySlice(elem_ty) => self.ty_size(elem_ty),
 748                             _ => panic!("indexing expected an array or slice, got {:?}", base_ty),
 749                         };
 750                         let n_ptr = try!(self.eval_operand(operand));
 751                         let n = try!(self.memory.read_usize(n_ptr));
 752                         base_ptr.offset(n as isize * elem_size as isize)
 753                     }
 754
 755                     ConstantIndex { .. } => unimplemented!(),
 756                 }
 757             }
 758         };
 759
 760         Ok(Lvalue { ptr: ptr, extra: LvalueExtra::None })
 761     }
 762
 763     // TODO(tsion): Try making const_to_primval instead.
 764     fn const_to_ptr(&mut self, const_val: &const_eval::ConstVal) -> EvalResult<Pointer> {
 765         use rustc::middle::const_eval::ConstVal::*;
 766         match *const_val {
 767             Float(_f) => unimplemented!(),
 768             Integral(int) => {
 769                 // TODO(tsion): Check int constant type.
 770                 let ptr = self.memory.allocate(8);
 771                 try!(self.memory.write_uint(ptr, int.to_u64_unchecked(), 8));
 772                 Ok(ptr)
 773             }
 774             Str(ref s) => {
 775                 let psize = self.memory.pointer_size;
 776                 let static_ptr = self.memory.allocate(s.len());
 777                 let ptr = self.memory.allocate(psize * 2);
 778                 try!(self.memory.write_bytes(static_ptr, s.as_bytes()));
 779                 try!(self.memory.write_ptr(ptr, static_ptr));
 780                 try!(self.memory.write_usize(ptr.offset(psize as isize), s.len() as u64));
 781                 Ok(ptr)
 782             }
 783             ByteStr(ref bs) => {
 784                 let psize = self.memory.pointer_size;
 785                 let static_ptr = self.memory.allocate(bs.len());
 786                 let ptr = self.memory.allocate(psize);
 787                 try!(self.memory.write_bytes(static_ptr, bs));
 788                 try!(self.memory.write_ptr(ptr, static_ptr));
 789                 Ok(ptr)
 790             }
 791             Bool(b) => {
 792                 let ptr = self.memory.allocate(1);
 793                 try!(self.memory.write_bool(ptr, b));
 794                 Ok(ptr)
 795             }
 796             Char(_c)          => unimplemented!(),
 797             Struct(_node_id)  => unimplemented!(),
 798             Tuple(_node_id)   => unimplemented!(),
 799             Function(_def_id) => unimplemented!(),
 800             Array(_, _)       => unimplemented!(),
 801             Repeat(_, _)      => unimplemented!(),
 802             Dummy             => unimplemented!(),
 803         }
 804     }
 805
 806     fn lvalue_ty(&self, lvalue: &mir::Lvalue<'tcx>) -> ty::Ty<'tcx> {
 807         self.monomorphize(self.mir().lvalue_ty(self.tcx, lvalue).to_ty(self.tcx))
 808     }
 809
 810     fn operand_ty(&self, operand: &mir::Operand<'tcx>) -> ty::Ty<'tcx> {
 811         self.monomorphize(self.mir().operand_ty(self.tcx, operand))
 812     }
 813
 814     fn monomorphize(&self, ty: ty::Ty<'tcx>) -> ty::Ty<'tcx> {
 815         let substituted = ty.subst(self.tcx, self.substs());
 816         infer::normalize_associated_type(self.tcx, &substituted)
 817     }
 818
 819     fn type_is_sized(&self, ty: ty::Ty<'tcx>) -> bool {
 820         ty.is_sized(&self.tcx.empty_parameter_environment(), DUMMY_SP)
 821     }
 822
 823     fn ty_size(&self, ty: ty::Ty<'tcx>) -> usize {
 824         self.ty_to_repr(ty).size()
 825     }
 826
 827     fn ty_to_repr(&self, ty: ty::Ty<'tcx>) -> &'arena Repr {
 828         let ty = self.monomorphize(ty);
 829
 830         if let Some(repr) = self.repr_cache.borrow().get(ty) {
 831             return repr;
 832         }
 833
 834         use syntax::ast::{IntTy, UintTy};
 835         let repr = match ty.sty {
 836             ty::TyBool => Repr::Primitive { size: 1 },
 837
 838             ty::TyInt(IntTy::I8)  | ty::TyUint(UintTy::U8)  => Repr::Primitive { size: 1 },
 839             ty::TyInt(IntTy::I16) | ty::TyUint(UintTy::U16) => Repr::Primitive { size: 2 },
 840             ty::TyInt(IntTy::I32) | ty::TyUint(UintTy::U32) => Repr::Primitive { size: 4 },
 841             ty::TyInt(IntTy::I64) | ty::TyUint(UintTy::U64) => Repr::Primitive { size: 8 },
 842
 843             ty::TyInt(IntTy::Is) | ty::TyUint(UintTy::Us) =>
 844                 Repr::Primitive { size: self.memory.pointer_size },
 845
 846             ty::TyTuple(ref fields) =>
 847                 self.make_aggregate_repr(iter::once(fields.iter().cloned())),
 848
 849             ty::TyEnum(adt_def, substs) | ty::TyStruct(adt_def, substs) => {
 850                 let variants = adt_def.variants.iter().map(|v| {
 851                     v.fields.iter().map(|f| f.ty(self.tcx, substs))
 852                 });
 853                 self.make_aggregate_repr(variants)
 854             }
 855
 856             ty::TyArray(elem_ty, length) => Repr::Array {
 857                 elem_size: self.ty_size(elem_ty),
 858                 length: length,
 859             },
 860
 861             ty::TyRef(_, ty::TypeAndMut { ty, .. }) |
 862             ty::TyRawPtr(ty::TypeAndMut { ty, .. }) |
 863             ty::TyBox(ty) => {
 864                 if self.type_is_sized(ty) {
 865                     Repr::Primitive { size: self.memory.pointer_size }
 866                 } else {
 867                     Repr::Primitive { size: self.memory.pointer_size * 2 }
 868                 }
 869             }
 870
 871             ty::TyFnPtr(..) => Repr::Primitive { size: self.memory.pointer_size },
 872
 873             ty::TyClosure(_, ref closure_substs) =>
 874                 self.make_aggregate_repr(iter::once(closure_substs.upvar_tys.iter().cloned())),
 875
 876             ref t => panic!("can't convert type to repr: {:?}", t),
 877         };
 878
 879         let repr_ref = self.repr_arena.alloc(repr);
 880         self.repr_cache.borrow_mut().insert(ty, repr_ref);
 881         repr_ref
 882     }
 883
 884     fn make_aggregate_repr<V>(&self, variant_fields: V) -> Repr
 885         where V: IntoIterator, V::Item: IntoIterator<Item = ty::Ty<'tcx>>
 886     {
 887         let mut variants = Vec::new();
 888         let mut max_variant_size = 0;
 889
 890         for field_tys in variant_fields {
 891             let mut fields = Vec::new();
 892             let mut size = 0;
 893
 894             for ty in field_tys {
 895                 let field_size = self.ty_size(ty);
 896                 let offest = size;
 897                 size += field_size;
 898                 fields.push(FieldRepr { offset: offest, size: field_size });
 899             }
 900
 901             if size > max_variant_size { max_variant_size = size; }
 902             variants.push(fields);
 903         }
 904
 905         let discr_size = match variants.len() {
 906             n if n <= 1       => 0,
 907             n if n <= 1 << 8  => 1,
 908             n if n <= 1 << 16 => 2,
 909             n if n <= 1 << 32 => 4,
 910             _                 => 8,
 911         };
 912         Repr::Aggregate {
 913             discr_size: discr_size,
 914             size: max_variant_size + discr_size,
 915             variants: variants,
 916         }
 917     }
 918
 919     pub fn read_primval(&mut self, ptr: Pointer, ty: ty::Ty<'tcx>) -> EvalResult<PrimVal> {
 920         use syntax::ast::{IntTy, UintTy};
 921         let val = match ty.sty {
 922             ty::TyBool              => PrimVal::Bool(try!(self.memory.read_bool(ptr))),
 923             ty::TyInt(IntTy::I8)    => PrimVal::I8(try!(self.memory.read_int(ptr, 1)) as i8),
 924             ty::TyInt(IntTy::I16)   => PrimVal::I16(try!(self.memory.read_int(ptr, 2)) as i16),
 925             ty::TyInt(IntTy::I32)   => PrimVal::I32(try!(self.memory.read_int(ptr, 4)) as i32),
 926             ty::TyInt(IntTy::I64)   => PrimVal::I64(try!(self.memory.read_int(ptr, 8)) as i64),
 927             ty::TyUint(UintTy::U8)  => PrimVal::U8(try!(self.memory.read_uint(ptr, 1)) as u8),
 928             ty::TyUint(UintTy::U16) => PrimVal::U16(try!(self.memory.read_uint(ptr, 2)) as u16),
 929             ty::TyUint(UintTy::U32) => PrimVal::U32(try!(self.memory.read_uint(ptr, 4)) as u32),
 930             ty::TyUint(UintTy::U64) => PrimVal::U64(try!(self.memory.read_uint(ptr, 8)) as u64),
 931
 932             // TODO(tsion): Pick the PrimVal dynamically.
 933             ty::TyInt(IntTy::Is)   => PrimVal::I64(try!(self.memory.read_isize(ptr))),
 934             ty::TyUint(UintTy::Us) => PrimVal::U64(try!(self.memory.read_usize(ptr))),
 935
 936             ty::TyRef(_, ty::TypeAndMut { ty, .. }) |
 937             ty::TyRawPtr(ty::TypeAndMut { ty, .. }) => {
 938                 if self.type_is_sized(ty) {
 939                     match self.memory.read_ptr(ptr) {
 940                         Ok(p) => PrimVal::AbstractPtr(p),
 941                         Err(EvalError::ReadBytesAsPointer) => {
 942                             let n = try!(self.memory.read_usize(ptr));
 943                             PrimVal::IntegerPtr(n)
 944                         }
 945                         Err(e) => return Err(e),
 946                     }
 947                 } else {
 948                     panic!("unimplemented: primitive read of fat pointer type: {:?}", ty);
 949                 }
 950             }
 951
 952             _ => panic!("primitive read of non-primitive type: {:?}", ty),
 953         };
 954         Ok(val)
 955     }
 956
 957     fn frame(&self) -> &Frame<'a, 'tcx> {
 958         self.stack.last().expect("no call frames exist")
 959     }
 960
 961     fn frame_mut(&mut self) -> &mut Frame<'a, 'tcx> {
 962         self.stack.last_mut().expect("no call frames exist")
 963     }
 964
 965     fn mir(&self) -> &mir::Mir<'tcx> {
 966         &self.frame().mir
 967     }
 968
 969     fn substs(&self) -> &'tcx Substs<'tcx> {
 970         self.substs_stack.last().cloned().unwrap_or_else(|| self.tcx.mk_substs(Substs::empty()))
 971     }
 972
 973     fn load_mir(&self, def_id: DefId) -> CachedMir<'a, 'tcx> {
 974         match self.tcx.map.as_local_node_id(def_id) {
 975             Some(node_id) => CachedMir::Ref(self.mir_map.map.get(&node_id).unwrap()),
 976             None => {
 977                 let mut mir_cache = self.mir_cache.borrow_mut();
 978                 if let Some(mir) = mir_cache.get(&def_id) {
 979                     return CachedMir::Owned(mir.clone());
 980                 }
 981
 982                 use rustc::middle::cstore::CrateStore;
 983                 let cs = &self.tcx.sess.cstore;
 984                 let mir = cs.maybe_get_item_mir(self.tcx, def_id).unwrap_or_else(|| {
 985                     panic!("no mir for {:?}", def_id);
 986                 });
 987                 let cached = Rc::new(mir);
 988                 mir_cache.insert(def_id, cached.clone());
 989                 CachedMir::Owned(cached)
 990             }
 991         }
 992     }
 993
 994     fn fulfill_obligation(&self, trait_ref: ty::PolyTraitRef<'tcx>) -> traits::Vtable<'tcx, ()> {
 995         // Do the initial selection for the obligation. This yields the shallow result we are
 996         // looking for -- that is, what specific impl.
 997         let infcx = infer::normalizing_infer_ctxt(self.tcx, &self.tcx.tables, ProjectionMode::Any);
 998         let mut selcx = traits::SelectionContext::new(&infcx);
 999
1000         let obligation = traits::Obligation::new(
1001             traits::ObligationCause::misc(DUMMY_SP, ast::DUMMY_NODE_ID),
1002             trait_ref.to_poly_trait_predicate(),
1003         );
1004         let selection = selcx.select(&obligation).unwrap().unwrap();
1005
1006         // Currently, we use a fulfillment context to completely resolve all nested obligations.
1007         // This is because they can inform the inference of the impl's type parameters.
1008         let mut fulfill_cx = traits::FulfillmentContext::new();
1009         let vtable = selection.map(|predicate| {
1010             fulfill_cx.register_predicate_obligation(&infcx, predicate);
1011         });
1012         let vtable = infer::drain_fulfillment_cx_or_panic(
1013             DUMMY_SP, &infcx, &mut fulfill_cx, &vtable
1014         );
1015
1016         vtable
1017     }
1018
1019     /// Trait method, which has to be resolved to an impl method.
1020     pub fn trait_method(&self, def_id: DefId, substs: &'tcx Substs<'tcx>)
1021         -> (DefId, &'tcx Substs<'tcx>)
1022     {
1023         let method_item = self.tcx.impl_or_trait_item(def_id);
1024         let trait_id = method_item.container().id();
1025         let trait_ref = ty::Binder(substs.to_trait_ref(self.tcx, trait_id));
1026         match self.fulfill_obligation(trait_ref) {
1027             traits::VtableImpl(vtable_impl) => {
1028                 let impl_did = vtable_impl.impl_def_id;
1029                 let mname = self.tcx.item_name(def_id);
1030                 // Create a concatenated set of substitutions which includes those from the impl
1031                 // and those from the method:
1032                 let impl_substs = vtable_impl.substs.with_method_from(substs);
1033                 let substs = self.tcx.mk_substs(impl_substs);
1034                 let mth = get_impl_method(self.tcx, impl_did, substs, mname);
1035
1036                 (mth.method.def_id, mth.substs)
1037             }
1038
1039             traits::VtableClosure(vtable_closure) =>
1040                 (vtable_closure.closure_def_id, vtable_closure.substs.func_substs),
1041
1042             traits::VtableFnPointer(_fn_ty) => {
1043                 let _trait_closure_kind = self.tcx.lang_items.fn_trait_kind(trait_id).unwrap();
1044                 unimplemented!()
1045                 // let llfn = trans_fn_pointer_shim(ccx, trait_closure_kind, fn_ty);
1046
1047                 // let method_ty = def_ty(tcx, def_id, substs);
1048                 // let fn_ptr_ty = match method_ty.sty {
1049                 //     ty::TyFnDef(_, _, fty) => tcx.mk_ty(ty::TyFnPtr(fty)),
1050                 //     _ => unreachable!("expected fn item type, found {}",
1051                 //                       method_ty)
1052                 // };
1053                 // Callee::ptr(immediate_rvalue(llfn, fn_ptr_ty))
1054             }
1055
1056             traits::VtableObject(ref _data) => {
1057                 unimplemented!()
1058                 // Callee {
1059                 //     data: Virtual(traits::get_vtable_index_of_object_method(
1060                 //                   tcx, data, def_id)),
1061                 //                   ty: def_ty(tcx, def_id, substs)
1062                 // }
1063             }
1064             vtable => unreachable!("resolved vtable bad vtable {:?} in trans", vtable),
1065         }
1066     }
1067 }
1068
1069 fn pointee_type<'tcx>(ptr_ty: ty::Ty<'tcx>) -> Option<ty::Ty<'tcx>> {
1070     match ptr_ty.sty {
1071         ty::TyRef(_, ty::TypeAndMut { ty, .. }) |
1072         ty::TyRawPtr(ty::TypeAndMut { ty, .. }) |
1073         ty::TyBox(ty) => {
1074             Some(ty)
1075         }
1076         _ => None,
1077     }
1078 }
1079
1080 impl Lvalue {
1081     fn to_ptr(self) -> Pointer {
1082         assert_eq!(self.extra, LvalueExtra::None);
1083         self.ptr
1084     }
1085 }
1086
1087 impl<'mir, 'tcx: 'mir> Deref for CachedMir<'mir, 'tcx> {
1088     type Target = mir::Mir<'tcx>;
1089     fn deref(&self) -> &mir::Mir<'tcx> {
1090         match *self {
1091             CachedMir::Ref(r) => r,
1092             CachedMir::Owned(ref rc) => &rc,
1093         }
1094     }
1095 }
1096
1097 #[derive(Debug)]
1098 pub struct ImplMethod<'tcx> {
1099     pub method: Rc<ty::Method<'tcx>>,
1100     pub substs: &'tcx Substs<'tcx>,
1101     pub is_provided: bool,
1102 }
1103
1104 /// Locates the applicable definition of a method, given its name.
1105 pub fn get_impl_method<'tcx>(
1106     tcx: &TyCtxt<'tcx>,
1107     impl_def_id: DefId,
1108     substs: &'tcx Substs<'tcx>,
1109     name: ast::Name,
1110 ) -> ImplMethod<'tcx> {
1111     assert!(!substs.types.needs_infer());
1112
1113     let trait_def_id = tcx.trait_id_of_impl(impl_def_id).unwrap();
1114     let trait_def = tcx.lookup_trait_def(trait_def_id);
1115     let infcx = infer::normalizing_infer_ctxt(tcx, &tcx.tables, ProjectionMode::Any);
1116
1117     match trait_def.ancestors(impl_def_id).fn_defs(tcx, name).next() {
1118         Some(node_item) => {
1119             ImplMethod {
1120                 method: node_item.item,
1121                 substs: traits::translate_substs(&infcx, impl_def_id, substs, node_item.node),
1122                 is_provided: node_item.node.is_from_trait(),
1123             }
1124         }
1125         None => {
1126             tcx.sess.bug(&format!("method {:?} not found in {:?}", name, impl_def_id))
1127         }
1128     }
1129 }
1130
1131 pub fn interpret_start_points<'tcx>(tcx: &TyCtxt<'tcx>, mir_map: &MirMap<'tcx>) {
1132     /// Print the given allocation and all allocations it depends on.
1133     fn print_allocation_tree(memory: &Memory, alloc_id: memory::AllocId) {
1134         let alloc = memory.get(alloc_id).unwrap();
1135         println!("  {:?}: {:?}", alloc_id, alloc);
1136         for &target_alloc in alloc.relocations.values() {
1137             print_allocation_tree(memory, target_alloc);
1138         }
1139     }
1140
1141     for (&id, mir) in &mir_map.map {
1142         for attr in tcx.map.attrs(id) {
1143             use syntax::attr::AttrMetaMethods;
1144             if attr.check_name("miri_run") {
1145                 let item = tcx.map.expect_item(id);
1146
1147                 println!("Interpreting: {}", item.name);
1148
1149                 let repr_arena = TypedArena::new();
1150                 let mut miri = Interpreter::new(tcx, mir_map, &repr_arena);
1151                 let return_ptr = match mir.return_ty {
1152                     ty::FnConverging(ty) => {
1153                         let size = miri.ty_size(ty);
1154                         Some(miri.memory.allocate(size))
1155                     }
1156                     ty::FnDiverging => None,
1157                 };
1158                 miri.push_stack_frame(CachedMir::Ref(mir), return_ptr);
1159                 if let Err(_e) = miri.run() {
1160                     // // TODO(tsion): report error
1161                     // let err = tcx.struct_err()
1162                 }
1163                 tcx.sess.abort_if_errors();
1164
1165                 if let Some(ret) = return_ptr {
1166                     println!("Result:");
1167                     print_allocation_tree(&miri.memory, ret.alloc_id);
1168                     println!("");
1169                 }
1170             }
1171         }
1172     }
1173 }