src/interpreter/mod.rs

   1 use rustc::middle::const_val;
   2 use rustc::hir::def_id::DefId;
   3 use rustc::mir::mir_map::MirMap;
   4 use rustc::mir::repr as mir;
   5 use rustc::traits::{self, ProjectionMode};
   6 use rustc::ty::fold::TypeFoldable;
   7 use rustc::ty::layout::{self, Layout, Size};
   8 use rustc::ty::subst::{self, Subst, Substs};
   9 use rustc::ty::{self, Ty, TyCtxt};
  10 use rustc::util::nodemap::DefIdMap;
  11 use std::cell::RefCell;
  12 use std::ops::{Deref, DerefMut};
  13 use std::rc::Rc;
  14 use std::{iter, mem};
  15 use syntax::ast;
  16 use syntax::attr;
  17 use syntax::codemap::{self, DUMMY_SP, Span};
  18
  19 use error::{EvalError, EvalResult};
  20 use memory::{Memory, Pointer};
  21 use primval::{self, PrimVal};
  22
  23 use std::collections::HashMap;
  24
  25 mod stepper;
  26
  27 struct GlobalEvalContext<'a, 'tcx: 'a> {
  28     /// The results of the type checker, from rustc.
  29     tcx: TyCtxt<'a, 'tcx, '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     /// The virtual memory system.
  38     memory: Memory,
  39
  40     /// Precomputed statics and constants
  41     statics: DefIdMap<Pointer>,
  42 }
  43
  44 struct FnEvalContext<'a, 'b: 'a + 'mir, 'mir, 'tcx: 'b> {
  45     gecx: &'a mut GlobalEvalContext<'b, 'tcx>,
  46
  47     /// The virtual call stack.
  48     stack: Vec<Frame<'mir, 'tcx>>,
  49 }
  50
  51 impl<'a, 'b, 'mir, 'tcx> Deref for FnEvalContext<'a, 'b, 'mir, 'tcx> {
  52     type Target = GlobalEvalContext<'b, 'tcx>;
  53     fn deref(&self) -> &Self::Target {
  54         self.gecx
  55     }
  56 }
  57
  58 impl<'a, 'b, 'mir, 'tcx> DerefMut for FnEvalContext<'a, 'b, 'mir, 'tcx> {
  59     fn deref_mut(&mut self) -> &mut Self::Target {
  60         self.gecx
  61     }
  62 }
  63
  64 /// A stack frame.
  65 struct Frame<'a, 'tcx: 'a> {
  66     /// The def_id of the current function
  67     def_id: DefId,
  68
  69     /// The span of the call site
  70     span: codemap::Span,
  71
  72     /// type substitutions for the current function invocation
  73     substs: &'tcx Substs<'tcx>,
  74
  75     /// The MIR for the function called on this frame.
  76     mir: CachedMir<'a, 'tcx>,
  77
  78     /// The block that is currently executed (or will be executed after the above call stacks return)
  79     next_block: mir::BasicBlock,
  80
  81     /// A pointer for writing the return value of the current call if it's not a diverging call.
  82     return_ptr: Option<Pointer>,
  83
  84     /// The list of locals for the current function, stored in order as
  85     /// `[arguments..., variables..., temporaries...]`. The variables begin at `self.var_offset`
  86     /// and the temporaries at `self.temp_offset`.
  87     locals: Vec<Pointer>,
  88
  89     /// The offset of the first variable in `self.locals`.
  90     var_offset: usize,
  91
  92     /// The offset of the first temporary in `self.locals`.
  93     temp_offset: usize,
  94
  95     /// List of precomputed promoted constants
  96     promoted: HashMap<usize, Pointer>,
  97
  98     /// The index of the currently evaluated statment
  99     stmt: usize,
 100
 101     // Constants that need to be evaluated before the next statement can be evaluated
 102     constants: Vec<(ConstantId<'tcx>, Span, Pointer, CachedMir<'a, 'tcx>)>,
 103 }
 104
 105 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 106 struct Lvalue {
 107     ptr: Pointer,
 108     extra: LvalueExtra,
 109 }
 110
 111 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 112 enum LvalueExtra {
 113     None,
 114     Length(u64),
 115     // TODO(solson): Vtable(memory::AllocId),
 116     DowncastVariant(usize),
 117 }
 118
 119 #[derive(Clone)]
 120 enum CachedMir<'mir, 'tcx: 'mir> {
 121     Ref(&'mir mir::Mir<'tcx>),
 122     Owned(Rc<mir::Mir<'tcx>>)
 123 }
 124
 125 /// Represents the action to be taken in the main loop as a result of executing a terminator.
 126 enum TerminatorTarget {
 127     /// Make a local jump to the next block
 128     Block,
 129
 130     /// Start executing from the new current frame. (For function calls.)
 131     Call,
 132
 133     /// Stop executing the current frame and resume the previous frame.
 134     Return,
 135 }
 136
 137 #[derive(Clone, Debug, Eq, PartialEq, Hash)]
 138 enum ConstantId<'tcx> {
 139     Promoted { index: usize },
 140     Static { def_id: DefId, substs: &'tcx Substs<'tcx> },
 141 }
 142
 143
 144 impl<'a, 'tcx> GlobalEvalContext<'a, 'tcx> {
 145     fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>, mir_map: &'a MirMap<'tcx>) -> Self {
 146         GlobalEvalContext {
 147             tcx: tcx,
 148             mir_map: mir_map,
 149             mir_cache: RefCell::new(DefIdMap()),
 150             memory: Memory::new(tcx.sess
 151                                    .target
 152                                    .uint_type
 153                                    .bit_width()
 154                                    .expect("Session::target::uint_type was usize")/8),
 155             statics: DefIdMap(),
 156         }
 157     }
 158
 159     fn call(&mut self, mir: &mir::Mir<'tcx>, def_id: DefId) -> EvalResult<Option<Pointer>> {
 160         let substs = self.tcx.mk_substs(subst::Substs::empty());
 161
 162         let mut nested_fecx = FnEvalContext::new(self);
 163
 164         nested_fecx.push_stack_frame(def_id, mir.span, CachedMir::Ref(mir), substs, None);
 165         let return_ptr = nested_fecx.alloc_ret_ptr(mir.return_ty);
 166         nested_fecx.frame_mut().return_ptr = return_ptr;
 167
 168         nested_fecx.run()?;
 169         Ok(return_ptr)
 170     }
 171 }
 172
 173 impl<'a, 'b, 'mir, 'tcx> FnEvalContext<'a, 'b, 'mir, 'tcx> {
 174     fn new(gecx: &'a mut GlobalEvalContext<'b, 'tcx>) -> Self {
 175         FnEvalContext {
 176             gecx: gecx,
 177             stack: Vec::new(),
 178         }
 179     }
 180
 181     fn alloc_ret_ptr(&mut self, ty: ty::FnOutput<'tcx>) -> Option<Pointer> {
 182         match ty {
 183             ty::FnConverging(ty) => {
 184                 let size = self.type_size(ty);
 185                 Some(self.memory.allocate(size))
 186             }
 187             ty::FnDiverging => None,
 188         }
 189     }
 190
 191     fn maybe_report<T>(&self, span: codemap::Span, r: EvalResult<T>) -> EvalResult<T> {
 192         if let Err(ref e) = r {
 193             let mut err = self.tcx.sess.struct_span_err(span, &e.to_string());
 194             for &Frame{ def_id, substs, span, .. } in self.stack.iter().rev() {
 195                 // FIXME(solson): Find a way to do this without this Display impl hack.
 196                 use rustc::util::ppaux;
 197                 use std::fmt;
 198                 struct Instance<'tcx>(DefId, &'tcx Substs<'tcx>);
 199                 impl<'tcx> fmt::Display for Instance<'tcx> {
 200                     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 201                         ppaux::parameterized(f, self.1, self.0, ppaux::Ns::Value, &[],
 202                             |tcx| tcx.lookup_item_type(self.0).generics)
 203                     }
 204                 }
 205                 err.span_note(span, &format!("inside call to {}", Instance(def_id, substs)));
 206             }
 207             err.emit();
 208         }
 209         r
 210     }
 211
 212     fn run(&mut self) -> EvalResult<()> {
 213         let mut stepper = stepper::Stepper::new(self);
 214         'outer: loop {
 215             use self::stepper::Event::*;
 216             trace!("// {:?}", stepper.block());
 217
 218             loop {
 219                 match stepper.step()? {
 220                     Constant => trace!("next statement requires the computation of a constant"),
 221                     Assignment => trace!("{:?}", stepper.stmt()),
 222                     Terminator => {
 223                         trace!("{:?}", stepper.term().kind);
 224                         continue 'outer;
 225                     },
 226                     Done => return Ok(()),
 227                 }
 228             }
 229         }
 230     }
 231
 232     fn push_stack_frame(&mut self, def_id: DefId, span: codemap::Span, mir: CachedMir<'mir, 'tcx>, substs: &'tcx Substs<'tcx>,
 233         return_ptr: Option<Pointer>)
 234     {
 235         let arg_tys = mir.arg_decls.iter().map(|a| a.ty);
 236         let var_tys = mir.var_decls.iter().map(|v| v.ty);
 237         let temp_tys = mir.temp_decls.iter().map(|t| t.ty);
 238
 239         let num_args = mir.arg_decls.len();
 240         let num_vars = mir.var_decls.len();
 241
 242         ::log_settings::settings().indentation += 1;
 243
 244         self.stack.push(Frame {
 245             mir: mir.clone(),
 246             next_block: mir::START_BLOCK,
 247             return_ptr: return_ptr,
 248             locals: Vec::new(),
 249             var_offset: num_args,
 250             temp_offset: num_args + num_vars,
 251             promoted: HashMap::new(),
 252             span: span,
 253             def_id: def_id,
 254             substs: substs,
 255             stmt: 0,
 256             constants: Vec::new(),
 257         });
 258
 259         let locals: Vec<Pointer> = arg_tys.chain(var_tys).chain(temp_tys).map(|ty| {
 260             let size = self.type_size(ty);
 261             self.memory.allocate(size)
 262         }).collect();
 263
 264         self.frame_mut().locals = locals;
 265     }
 266
 267     fn pop_stack_frame(&mut self) {
 268         ::log_settings::settings().indentation -= 1;
 269         let _frame = self.stack.pop().expect("tried to pop a stack frame, but there were none");
 270         // TODO(solson): Deallocate local variables.
 271     }
 272
 273     fn eval_terminator(&mut self, terminator: &mir::Terminator<'tcx>)
 274             -> EvalResult<TerminatorTarget> {
 275         use rustc::mir::repr::TerminatorKind::*;
 276         let target = match terminator.kind {
 277             Return => TerminatorTarget::Return,
 278
 279             Goto { target } => {
 280                 self.frame_mut().next_block = target;
 281                 TerminatorTarget::Block
 282             },
 283
 284             If { ref cond, targets: (then_target, else_target) } => {
 285                 let cond_ptr = self.eval_operand(cond)?;
 286                 let cond_val = self.memory.read_bool(cond_ptr)?;
 287                 self.frame_mut().next_block = if cond_val { then_target } else { else_target };
 288                 TerminatorTarget::Block
 289             }
 290
 291             SwitchInt { ref discr, ref values, ref targets, .. } => {
 292                 let discr_ptr = self.eval_lvalue(discr)?.to_ptr();
 293                 let discr_size = self
 294                     .type_layout(self.lvalue_ty(discr))
 295                     .size(&self.tcx.data_layout)
 296                     .bytes() as usize;
 297                 let discr_val = self.memory.read_uint(discr_ptr, discr_size)?;
 298
 299                 // Branch to the `otherwise` case by default, if no match is found.
 300                 let mut target_block = targets[targets.len() - 1];
 301
 302                 for (index, val_const) in values.iter().enumerate() {
 303                     let ptr = self.const_to_ptr(val_const)?;
 304                     let val = self.memory.read_uint(ptr, discr_size)?;
 305                     if discr_val == val {
 306                         target_block = targets[index];
 307                         break;
 308                     }
 309                 }
 310
 311                 self.frame_mut().next_block = target_block;
 312                 TerminatorTarget::Block
 313             }
 314
 315             Switch { ref discr, ref targets, adt_def } => {
 316                 let adt_ptr = self.eval_lvalue(discr)?.to_ptr();
 317                 let adt_ty = self.lvalue_ty(discr);
 318                 let discr_val = self.read_discriminant_value(adt_ptr, adt_ty)?;
 319                 let matching = adt_def.variants.iter()
 320                     .position(|v| discr_val == v.disr_val.to_u64_unchecked());
 321
 322                 match matching {
 323                     Some(i) => {
 324                         self.frame_mut().next_block = targets[i];
 325                         TerminatorTarget::Block
 326                     },
 327                     None => return Err(EvalError::InvalidDiscriminant),
 328                 }
 329             }
 330
 331             Call { ref func, ref args, ref destination, .. } => {
 332                 let mut return_ptr = None;
 333                 if let Some((ref lv, target)) = *destination {
 334                     self.frame_mut().next_block = target;
 335                     return_ptr = Some(self.eval_lvalue(lv)?.to_ptr());
 336                 }
 337
 338                 let func_ty = self.operand_ty(func);
 339                 match func_ty.sty {
 340                     ty::TyFnDef(def_id, substs, fn_ty) => {
 341                         use syntax::abi::Abi;
 342                         match fn_ty.abi {
 343                             Abi::RustIntrinsic => {
 344                                 let name = self.tcx.item_name(def_id).as_str();
 345                                 match fn_ty.sig.0.output {
 346                                     ty::FnConverging(ty) => {
 347                                         let size = self.type_size(ty);
 348                                         let ret = return_ptr.unwrap();
 349                                         self.call_intrinsic(&name, substs, args, ret, size)?
 350                                     }
 351                                     ty::FnDiverging => unimplemented!(),
 352                                 }
 353                             }
 354
 355                             Abi::C => {
 356                                 match fn_ty.sig.0.output {
 357                                     ty::FnConverging(ty) => {
 358                                         let size = self.type_size(ty);
 359                                         self.call_c_abi(def_id, args, return_ptr.unwrap(), size)?
 360                                     }
 361                                     ty::FnDiverging => unimplemented!(),
 362                                 }
 363                             }
 364
 365                             Abi::Rust | Abi::RustCall => {
 366                                 // TODO(solson): Adjust the first argument when calling a Fn or
 367                                 // FnMut closure via FnOnce::call_once.
 368
 369                                 // Only trait methods can have a Self parameter.
 370                                 let (resolved_def_id, resolved_substs) = if substs.self_ty().is_some() {
 371                                     self.trait_method(def_id, substs)
 372                                 } else {
 373                                     (def_id, substs)
 374                                 };
 375
 376                                 let mut arg_srcs = Vec::new();
 377                                 for arg in args {
 378                                     let src = self.eval_operand(arg)?;
 379                                     let src_ty = self.operand_ty(arg);
 380                                     arg_srcs.push((src, src_ty));
 381                                 }
 382
 383                                 if fn_ty.abi == Abi::RustCall && !args.is_empty() {
 384                                     arg_srcs.pop();
 385                                     let last_arg = args.last().unwrap();
 386                                     let last = self.eval_operand(last_arg)?;
 387                                     let last_ty = self.operand_ty(last_arg);
 388                                     let last_layout = self.type_layout(last_ty);
 389                                     match (&last_ty.sty, last_layout) {
 390                                         (&ty::TyTuple(fields),
 391                                          &Layout::Univariant { ref variant, .. }) => {
 392                                             let offsets = iter::once(0)
 393                                                 .chain(variant.offset_after_field.iter()
 394                                                     .map(|s| s.bytes()));
 395                                             for (offset, ty) in offsets.zip(fields) {
 396                                                 let src = last.offset(offset as isize);
 397                                                 arg_srcs.push((src, ty));
 398                                             }
 399                                         }
 400                                         ty => panic!("expected tuple as last argument in function with 'rust-call' ABI, got {:?}", ty),
 401                                     }
 402                                 }
 403
 404                                 let mir = self.load_mir(resolved_def_id);
 405                                 self.push_stack_frame(def_id, terminator.span, mir, resolved_substs, return_ptr);
 406
 407                                 for (i, (src, src_ty)) in arg_srcs.into_iter().enumerate() {
 408                                     let dest = self.frame().locals[i];
 409                                     self.move_(src, dest, src_ty)?;
 410                                 }
 411
 412                                 TerminatorTarget::Call
 413                             }
 414
 415                             abi => return Err(EvalError::Unimplemented(format!("can't handle function with {:?} ABI", abi))),
 416                         }
 417                     }
 418
 419                     _ => return Err(EvalError::Unimplemented(format!("can't handle callee of type {:?}", func_ty))),
 420                 }
 421             }
 422
 423             Drop { ref value, target, .. } => {
 424                 let ptr = self.eval_lvalue(value)?.to_ptr();
 425                 let ty = self.lvalue_ty(value);
 426                 self.drop(ptr, ty)?;
 427                 self.frame_mut().next_block = target;
 428                 TerminatorTarget::Block
 429             }
 430
 431             Resume => unimplemented!(),
 432         };
 433
 434         Ok(target)
 435     }
 436
 437     fn drop(&mut self, ptr: Pointer, ty: Ty<'tcx>) -> EvalResult<()> {
 438         if !self.type_needs_drop(ty) {
 439             debug!("no need to drop {:?}", ty);
 440             return Ok(());
 441         }
 442         trace!("-need to drop {:?}", ty);
 443
 444         // TODO(solson): Call user-defined Drop::drop impls.
 445
 446         match ty.sty {
 447             ty::TyBox(contents_ty) => {
 448                 match self.memory.read_ptr(ptr) {
 449                     Ok(contents_ptr) => {
 450                         self.drop(contents_ptr, contents_ty)?;
 451                         trace!("-deallocating box");
 452                         self.memory.deallocate(contents_ptr)?;
 453                     }
 454                     Err(EvalError::ReadBytesAsPointer) => {
 455                         let size = self.memory.pointer_size;
 456                         let possible_drop_fill = self.memory.read_bytes(ptr, size)?;
 457                         if possible_drop_fill.iter().all(|&b| b == mem::POST_DROP_U8) {
 458                             return Ok(());
 459                         } else {
 460                             return Err(EvalError::ReadBytesAsPointer);
 461                         }
 462                     }
 463                     Err(e) => return Err(e),
 464                 }
 465             }
 466
 467             // TODO(solson): Implement drop for other relevant types (e.g. aggregates).
 468             _ => {}
 469         }
 470
 471         // Filling drop.
 472         // FIXME(solson): Trait objects (with no static size) probably get filled, too.
 473         let size = self.type_size(ty);
 474         self.memory.drop_fill(ptr, size)?;
 475
 476         Ok(())
 477     }
 478
 479     fn read_discriminant_value(&self, adt_ptr: Pointer, adt_ty: Ty<'tcx>) -> EvalResult<u64> {
 480         use rustc::ty::layout::Layout::*;
 481         let adt_layout = self.type_layout(adt_ty);
 482
 483         let discr_val = match *adt_layout {
 484             General { discr, .. } | CEnum { discr, .. } => {
 485                 let discr_size = discr.size().bytes();
 486                 self.memory.read_uint(adt_ptr, discr_size as usize)?
 487             }
 488
 489             RawNullablePointer { nndiscr, .. } => {
 490                 self.read_nonnull_discriminant_value(adt_ptr, nndiscr)?
 491             }
 492
 493             StructWrappedNullablePointer { nndiscr, ref discrfield, .. } => {
 494                 let offset = self.nonnull_offset(adt_ty, nndiscr, discrfield)?;
 495                 let nonnull = adt_ptr.offset(offset.bytes() as isize);
 496                 self.read_nonnull_discriminant_value(nonnull, nndiscr)?
 497             }
 498
 499             // The discriminant_value intrinsic returns 0 for non-sum types.
 500             Array { .. } | FatPointer { .. } | Scalar { .. } | Univariant { .. } |
 501             Vector { .. } => 0,
 502         };
 503
 504         Ok(discr_val)
 505     }
 506
 507     fn read_nonnull_discriminant_value(&self, ptr: Pointer, nndiscr: u64) -> EvalResult<u64> {
 508         let not_null = match self.memory.read_usize(ptr) {
 509             Ok(0) => false,
 510             Ok(_) | Err(EvalError::ReadPointerAsBytes) => true,
 511             Err(e) => return Err(e),
 512         };
 513         assert!(nndiscr == 0 || nndiscr == 1);
 514         Ok(if not_null { nndiscr } else { 1 - nndiscr })
 515     }
 516
 517     fn call_intrinsic(
 518         &mut self,
 519         name: &str,
 520         substs: &'tcx Substs<'tcx>,
 521         args: &[mir::Operand<'tcx>],
 522         dest: Pointer,
 523         dest_size: usize
 524     ) -> EvalResult<TerminatorTarget> {
 525         let args_res: EvalResult<Vec<Pointer>> = args.iter()
 526             .map(|arg| self.eval_operand(arg))
 527             .collect();
 528         let args = args_res?;
 529
 530         match name {
 531             // FIXME(solson): Handle different integer types correctly.
 532             "add_with_overflow" => {
 533                 let ty = *substs.types.get(subst::FnSpace, 0);
 534                 let size = self.type_size(ty);
 535                 let left = self.memory.read_int(args[0], size)?;
 536                 let right = self.memory.read_int(args[1], size)?;
 537                 let (n, overflowed) = unsafe {
 538                     ::std::intrinsics::add_with_overflow::<i64>(left, right)
 539                 };
 540                 self.memory.write_int(dest, n, size)?;
 541                 self.memory.write_bool(dest.offset(size as isize), overflowed)?;
 542             }
 543
 544             "assume" => {}
 545
 546             "copy_nonoverlapping" => {
 547                 let elem_ty = *substs.types.get(subst::FnSpace, 0);
 548                 let elem_size = self.type_size(elem_ty);
 549                 let src = self.memory.read_ptr(args[0])?;
 550                 let dest = self.memory.read_ptr(args[1])?;
 551                 let count = self.memory.read_isize(args[2])?;
 552                 self.memory.copy(src, dest, count as usize * elem_size)?;
 553             }
 554
 555             "discriminant_value" => {
 556                 let ty = *substs.types.get(subst::FnSpace, 0);
 557                 let adt_ptr = self.memory.read_ptr(args[0])?;
 558                 let discr_val = self.read_discriminant_value(adt_ptr, ty)?;
 559                 self.memory.write_uint(dest, discr_val, dest_size)?;
 560             }
 561
 562             "forget" => {
 563                 let arg_ty = *substs.types.get(subst::FnSpace, 0);
 564                 let arg_size = self.type_size(arg_ty);
 565                 self.memory.drop_fill(args[0], arg_size)?;
 566             }
 567
 568             "init" => self.memory.write_repeat(dest, 0, dest_size)?,
 569
 570             "min_align_of" => {
 571                 self.memory.write_int(dest, 1, dest_size)?;
 572             }
 573
 574             "move_val_init" => {
 575                 let ty = *substs.types.get(subst::FnSpace, 0);
 576                 let ptr = self.memory.read_ptr(args[0])?;
 577                 self.move_(args[1], ptr, ty)?;
 578             }
 579
 580             // FIXME(solson): Handle different integer types correctly.
 581             "mul_with_overflow" => {
 582                 let ty = *substs.types.get(subst::FnSpace, 0);
 583                 let size = self.type_size(ty);
 584                 let left = self.memory.read_int(args[0], size)?;
 585                 let right = self.memory.read_int(args[1], size)?;
 586                 let (n, overflowed) = unsafe {
 587                     ::std::intrinsics::mul_with_overflow::<i64>(left, right)
 588                 };
 589                 self.memory.write_int(dest, n, size)?;
 590                 self.memory.write_bool(dest.offset(size as isize), overflowed)?;
 591             }
 592
 593             "offset" => {
 594                 let pointee_ty = *substs.types.get(subst::FnSpace, 0);
 595                 let pointee_size = self.type_size(pointee_ty) as isize;
 596                 let ptr_arg = args[0];
 597                 let offset = self.memory.read_isize(args[1])?;
 598
 599                 match self.memory.read_ptr(ptr_arg) {
 600                     Ok(ptr) => {
 601                         let result_ptr = ptr.offset(offset as isize * pointee_size);
 602                         self.memory.write_ptr(dest, result_ptr)?;
 603                     }
 604                     Err(EvalError::ReadBytesAsPointer) => {
 605                         let addr = self.memory.read_isize(ptr_arg)?;
 606                         let result_addr = addr + offset * pointee_size as i64;
 607                         self.memory.write_isize(dest, result_addr)?;
 608                     }
 609                     Err(e) => return Err(e),
 610                 }
 611             }
 612
 613             // FIXME(solson): Handle different integer types correctly. Use primvals?
 614             "overflowing_sub" => {
 615                 let ty = *substs.types.get(subst::FnSpace, 0);
 616                 let size = self.type_size(ty);
 617                 let left = self.memory.read_int(args[0], size)?;
 618                 let right = self.memory.read_int(args[1], size)?;
 619                 let n = left.wrapping_sub(right);
 620                 self.memory.write_int(dest, n, size)?;
 621             }
 622
 623             "size_of" => {
 624                 let ty = *substs.types.get(subst::FnSpace, 0);
 625                 let size = self.type_size(ty) as u64;
 626                 self.memory.write_uint(dest, size, dest_size)?;
 627             }
 628
 629             "size_of_val" => {
 630                 let ty = *substs.types.get(subst::FnSpace, 0);
 631                 if self.type_is_sized(ty) {
 632                     let size = self.type_size(ty) as u64;
 633                     self.memory.write_uint(dest, size, dest_size)?;
 634                 } else {
 635                     match ty.sty {
 636                         ty::TySlice(_) | ty::TyStr => {
 637                             let elem_ty = ty.sequence_element_type(self.tcx);
 638                             let elem_size = self.type_size(elem_ty) as u64;
 639                             let ptr_size = self.memory.pointer_size as isize;
 640                             let n = self.memory.read_usize(args[0].offset(ptr_size))?;
 641                             self.memory.write_uint(dest, n * elem_size, dest_size)?;
 642                         }
 643
 644                         _ => return Err(EvalError::Unimplemented(format!("unimplemented: size_of_val::<{:?}>", ty))),
 645                     }
 646                 }
 647             }
 648
 649             "transmute" => {
 650                 let ty = *substs.types.get(subst::FnSpace, 0);
 651                 self.move_(args[0], dest, ty)?;
 652             }
 653             "uninit" => self.memory.mark_definedness(dest, dest_size, false)?,
 654
 655             name => return Err(EvalError::Unimplemented(format!("unimplemented intrinsic: {}", name))),
 656         }
 657
 658         // Since we pushed no stack frame, the main loop will act
 659         // as if the call just completed and it's returning to the
 660         // current frame.
 661         Ok(TerminatorTarget::Call)
 662     }
 663
 664     fn call_c_abi(
 665         &mut self,
 666         def_id: DefId,
 667         args: &[mir::Operand<'tcx>],
 668         dest: Pointer,
 669         dest_size: usize,
 670     ) -> EvalResult<TerminatorTarget> {
 671         let name = self.tcx.item_name(def_id);
 672         let attrs = self.tcx.get_attrs(def_id);
 673         let link_name = match attr::first_attr_value_str_by_name(&attrs, "link_name") {
 674             Some(ln) => ln.clone(),
 675             None => name.as_str(),
 676         };
 677
 678         let args_res: EvalResult<Vec<Pointer>> = args.iter()
 679             .map(|arg| self.eval_operand(arg))
 680             .collect();
 681         let args = args_res?;
 682
 683         match &link_name[..] {
 684             "__rust_allocate" => {
 685                 let size = self.memory.read_usize(args[0])?;
 686                 let ptr = self.memory.allocate(size as usize);
 687                 self.memory.write_ptr(dest, ptr)?;
 688             }
 689
 690             "__rust_reallocate" => {
 691                 let ptr = self.memory.read_ptr(args[0])?;
 692                 let size = self.memory.read_usize(args[2])?;
 693                 self.memory.reallocate(ptr, size as usize)?;
 694                 self.memory.write_ptr(dest, ptr)?;
 695             }
 696
 697             "memcmp" => {
 698                 let left = self.memory.read_ptr(args[0])?;
 699                 let right = self.memory.read_ptr(args[1])?;
 700                 let n = self.memory.read_usize(args[2])? as usize;
 701
 702                 let result = {
 703                     let left_bytes = self.memory.read_bytes(left, n)?;
 704                     let right_bytes = self.memory.read_bytes(right, n)?;
 705
 706                     use std::cmp::Ordering::*;
 707                     match left_bytes.cmp(right_bytes) {
 708                         Less => -1,
 709                         Equal => 0,
 710                         Greater => 1,
 711                     }
 712                 };
 713
 714                 self.memory.write_int(dest, result, dest_size)?;
 715             }
 716
 717             _ => return Err(EvalError::Unimplemented(format!("can't call C ABI function: {}", link_name))),
 718         }
 719
 720         // Since we pushed no stack frame, the main loop will act
 721         // as if the call just completed and it's returning to the
 722         // current frame.
 723         Ok(TerminatorTarget::Call)
 724     }
 725
 726     fn assign_fields<I: IntoIterator<Item = u64>>(
 727         &mut self,
 728         dest: Pointer,
 729         offsets: I,
 730         operands: &[mir::Operand<'tcx>],
 731     ) -> EvalResult<()> {
 732         for (offset, operand) in offsets.into_iter().zip(operands) {
 733             let src = self.eval_operand(operand)?;
 734             let src_ty = self.operand_ty(operand);
 735             let field_dest = dest.offset(offset as isize);
 736             self.move_(src, field_dest, src_ty)?;
 737         }
 738         Ok(())
 739     }
 740
 741     fn eval_assignment(&mut self, lvalue: &mir::Lvalue<'tcx>, rvalue: &mir::Rvalue<'tcx>)
 742         -> EvalResult<()>
 743     {
 744         let dest = self.eval_lvalue(lvalue)?.to_ptr();
 745         let dest_ty = self.lvalue_ty(lvalue);
 746         let dest_layout = self.type_layout(dest_ty);
 747
 748         use rustc::mir::repr::Rvalue::*;
 749         match *rvalue {
 750             Use(ref operand) => {
 751                 let src = self.eval_operand(operand)?;
 752                 self.move_(src, dest, dest_ty)?;
 753             }
 754
 755             BinaryOp(bin_op, ref left, ref right) => {
 756                 let left_ptr = self.eval_operand(left)?;
 757                 let left_ty = self.operand_ty(left);
 758                 let left_val = self.read_primval(left_ptr, left_ty)?;
 759
 760                 let right_ptr = self.eval_operand(right)?;
 761                 let right_ty = self.operand_ty(right);
 762                 let right_val = self.read_primval(right_ptr, right_ty)?;
 763
 764                 let val = primval::binary_op(bin_op, left_val, right_val)?;
 765                 self.memory.write_primval(dest, val)?;
 766             }
 767
 768             UnaryOp(un_op, ref operand) => {
 769                 let ptr = self.eval_operand(operand)?;
 770                 let ty = self.operand_ty(operand);
 771                 let val = self.read_primval(ptr, ty)?;
 772                 self.memory.write_primval(dest, primval::unary_op(un_op, val)?)?;
 773             }
 774
 775             Aggregate(ref kind, ref operands) => {
 776                 use rustc::ty::layout::Layout::*;
 777                 match *dest_layout {
 778                     Univariant { ref variant, .. } => {
 779                         let offsets = iter::once(0)
 780                             .chain(variant.offset_after_field.iter().map(|s| s.bytes()));
 781                         self.assign_fields(dest, offsets, operands)?;
 782                     }
 783
 784                     Array { .. } => {
 785                         let elem_size = match dest_ty.sty {
 786                             ty::TyArray(elem_ty, _) => self.type_size(elem_ty) as u64,
 787                             _ => panic!("tried to assign {:?} to non-array type {:?}",
 788                                         kind, dest_ty),
 789                         };
 790                         let offsets = (0..).map(|i| i * elem_size);
 791                         self.assign_fields(dest, offsets, operands)?;
 792                     }
 793
 794                     General { discr, ref variants, .. } => {
 795                         if let mir::AggregateKind::Adt(adt_def, variant, _) = *kind {
 796                             let discr_val = adt_def.variants[variant].disr_val.to_u64_unchecked();
 797                             let discr_size = discr.size().bytes() as usize;
 798                             self.memory.write_uint(dest, discr_val, discr_size)?;
 799
 800                             let offsets = variants[variant].offset_after_field.iter()
 801                                 .map(|s| s.bytes());
 802                             self.assign_fields(dest, offsets, operands)?;
 803                         } else {
 804                             panic!("tried to assign {:?} to Layout::General", kind);
 805                         }
 806                     }
 807
 808                     RawNullablePointer { nndiscr, .. } => {
 809                         if let mir::AggregateKind::Adt(_, variant, _) = *kind {
 810                             if nndiscr == variant as u64 {
 811                                 assert_eq!(operands.len(), 1);
 812                                 let operand = &operands[0];
 813                                 let src = self.eval_operand(operand)?;
 814                                 let src_ty = self.operand_ty(operand);
 815                                 self.move_(src, dest, src_ty)?;
 816                             } else {
 817                                 assert_eq!(operands.len(), 0);
 818                                 self.memory.write_isize(dest, 0)?;
 819                             }
 820                         } else {
 821                             panic!("tried to assign {:?} to Layout::RawNullablePointer", kind);
 822                         }
 823                     }
 824
 825                     StructWrappedNullablePointer { nndiscr, ref nonnull, ref discrfield } => {
 826                         if let mir::AggregateKind::Adt(_, variant, _) = *kind {
 827                             if nndiscr == variant as u64 {
 828                                 let offsets = iter::once(0)
 829                                     .chain(nonnull.offset_after_field.iter().map(|s| s.bytes()));
 830                                 try!(self.assign_fields(dest, offsets, operands));
 831                             } else {
 832                                 assert_eq!(operands.len(), 0);
 833                                 let offset = self.nonnull_offset(dest_ty, nndiscr, discrfield)?;
 834                                 let dest = dest.offset(offset.bytes() as isize);
 835                                 try!(self.memory.write_isize(dest, 0));
 836                             }
 837                         } else {
 838                             panic!("tried to assign {:?} to Layout::RawNullablePointer", kind);
 839                         }
 840                     }
 841
 842                     CEnum { discr, signed, .. } => {
 843                         assert_eq!(operands.len(), 0);
 844                         if let mir::AggregateKind::Adt(adt_def, variant, _) = *kind {
 845                             let val = adt_def.variants[variant].disr_val.to_u64_unchecked();
 846                             let size = discr.size().bytes() as usize;
 847
 848                             if signed {
 849                                 self.memory.write_int(dest, val as i64, size)?;
 850                             } else {
 851                                 self.memory.write_uint(dest, val, size)?;
 852                             }
 853                         } else {
 854                             panic!("tried to assign {:?} to Layout::CEnum", kind);
 855                         }
 856                     }
 857
 858                     _ => return Err(EvalError::Unimplemented(format!("can't handle destination layout {:?} when assigning {:?}", dest_layout, kind))),
 859                 }
 860             }
 861
 862             Repeat(ref operand, _) => {
 863                 let (elem_size, length) = match dest_ty.sty {
 864                     ty::TyArray(elem_ty, n) => (self.type_size(elem_ty), n),
 865                     _ => panic!("tried to assign array-repeat to non-array type {:?}", dest_ty),
 866                 };
 867
 868                 let src = self.eval_operand(operand)?;
 869                 for i in 0..length {
 870                     let elem_dest = dest.offset((i * elem_size) as isize);
 871                     self.memory.copy(src, elem_dest, elem_size)?;
 872                 }
 873             }
 874
 875             Len(ref lvalue) => {
 876                 let src = self.eval_lvalue(lvalue)?;
 877                 let ty = self.lvalue_ty(lvalue);
 878                 let len = match ty.sty {
 879                     ty::TyArray(_, n) => n as u64,
 880                     ty::TySlice(_) => if let LvalueExtra::Length(n) = src.extra {
 881                         n
 882                     } else {
 883                         panic!("Rvalue::Len of a slice given non-slice pointer: {:?}", src);
 884                     },
 885                     _ => panic!("Rvalue::Len expected array or slice, got {:?}", ty),
 886                 };
 887                 self.memory.write_usize(dest, len)?;
 888             }
 889
 890             Ref(_, _, ref lvalue) => {
 891                 let lv = self.eval_lvalue(lvalue)?;
 892                 self.memory.write_ptr(dest, lv.ptr)?;
 893                 match lv.extra {
 894                     LvalueExtra::None => {},
 895                     LvalueExtra::Length(len) => {
 896                         let len_ptr = dest.offset(self.memory.pointer_size as isize);
 897                         self.memory.write_usize(len_ptr, len)?;
 898                     }
 899                     LvalueExtra::DowncastVariant(..) =>
 900                         panic!("attempted to take a reference to an enum downcast lvalue"),
 901                 }
 902             }
 903
 904             Box(ty) => {
 905                 let size = self.type_size(ty);
 906                 let ptr = self.memory.allocate(size);
 907                 self.memory.write_ptr(dest, ptr)?;
 908             }
 909
 910             Cast(kind, ref operand, dest_ty) => {
 911                 let src = self.eval_operand(operand)?;
 912                 let src_ty = self.operand_ty(operand);
 913
 914                 use rustc::mir::repr::CastKind::*;
 915                 match kind {
 916                     Unsize => {
 917                         self.move_(src, dest, src_ty)?;
 918                         let src_pointee_ty = pointee_type(src_ty).unwrap();
 919                         let dest_pointee_ty = pointee_type(dest_ty).unwrap();
 920
 921                         match (&src_pointee_ty.sty, &dest_pointee_ty.sty) {
 922                             (&ty::TyArray(_, length), &ty::TySlice(_)) => {
 923                                 let len_ptr = dest.offset(self.memory.pointer_size as isize);
 924                                 self.memory.write_usize(len_ptr, length as u64)?;
 925                             }
 926
 927                             _ => return Err(EvalError::Unimplemented(format!("can't handle cast: {:?}", rvalue))),
 928                         }
 929                     }
 930
 931                     Misc => {
 932                         // FIXME(solson): Wrong for almost everything.
 933                         let size = dest_layout.size(&self.tcx.data_layout).bytes() as usize;
 934                         self.memory.copy(src, dest, size)?;
 935                     }
 936
 937                     _ => return Err(EvalError::Unimplemented(format!("can't handle cast: {:?}", rvalue))),
 938                 }
 939             }
 940
 941             Slice { .. } => unimplemented!(),
 942             InlineAsm { .. } => unimplemented!(),
 943         }
 944
 945         Ok(())
 946     }
 947
 948     fn nonnull_offset(&self, ty: Ty<'tcx>, nndiscr: u64, discrfield: &[u32]) -> EvalResult<Size> {
 949         // Skip the constant 0 at the start meant for LLVM GEP.
 950         let mut path = discrfield.iter().skip(1).map(|&i| i as usize);
 951
 952         // Handle the field index for the outer non-null variant.
 953         let inner_ty = match ty.sty {
 954             ty::TyEnum(adt_def, substs) => {
 955                 let variant = &adt_def.variants[nndiscr as usize];
 956                 let index = path.next().unwrap();
 957                 let field = &variant.fields[index];
 958                 field.ty(self.tcx, substs)
 959             }
 960             _ => panic!(
 961                 "non-enum for StructWrappedNullablePointer: {}",
 962                 ty,
 963             ),
 964         };
 965
 966         self.field_path_offset(inner_ty, path)
 967     }
 968
 969     fn field_path_offset<I: Iterator<Item = usize>>(&self, mut ty: Ty<'tcx>, path: I) -> EvalResult<Size> {
 970         let mut offset = Size::from_bytes(0);
 971
 972         // Skip the initial 0 intended for LLVM GEP.
 973         for field_index in path {
 974             let field_offset = self.get_field_offset(ty, field_index)?;
 975             ty = self.get_field_ty(ty, field_index)?;
 976             offset = offset.checked_add(field_offset, &self.tcx.data_layout).unwrap();
 977         }
 978
 979         Ok(offset)
 980     }
 981
 982     fn get_field_ty(&self, ty: Ty<'tcx>, field_index: usize) -> EvalResult<Ty<'tcx>> {
 983         match ty.sty {
 984             ty::TyStruct(adt_def, substs) => {
 985                 Ok(adt_def.struct_variant().fields[field_index].ty(self.tcx, substs))
 986             }
 987
 988             ty::TyRef(_, ty::TypeAndMut { ty, .. }) |
 989             ty::TyRawPtr(ty::TypeAndMut { ty, .. }) |
 990             ty::TyBox(ty) => {
 991                 assert_eq!(field_index, 0);
 992                 Ok(ty)
 993             }
 994             _ => Err(EvalError::Unimplemented(format!("can't handle type: {:?}", ty))),
 995         }
 996     }
 997
 998     fn get_field_offset(&self, ty: Ty<'tcx>, field_index: usize) -> EvalResult<Size> {
 999         let layout = self.type_layout(ty);
1000
1001         use rustc::ty::layout::Layout::*;
1002         match *layout {
1003             Univariant { .. } => {
1004                 assert_eq!(field_index, 0);
1005                 Ok(Size::from_bytes(0))
1006             }
1007             FatPointer { .. } => {
1008                 let bytes = layout::FAT_PTR_ADDR * self.memory.pointer_size;
1009                 Ok(Size::from_bytes(bytes as u64))
1010             }
1011             _ => Err(EvalError::Unimplemented(format!("can't handle type: {:?}, with layout: {:?}", ty, layout))),
1012         }
1013     }
1014
1015     fn eval_operand(&mut self, op: &mir::Operand<'tcx>) -> EvalResult<Pointer> {
1016         use rustc::mir::repr::Operand::*;
1017         match *op {
1018             Consume(ref lvalue) => Ok(self.eval_lvalue(lvalue)?.to_ptr()),
1019             Constant(mir::Constant { ref literal, .. }) => {
1020                 use rustc::mir::repr::Literal::*;
1021                 match *literal {
1022                     Value { ref value } => Ok(self.const_to_ptr(value)?),
1023                     Item { def_id, substs } => {
1024                         let item_ty = self.tcx.lookup_item_type(def_id).subst(self.tcx, substs);
1025                         if item_ty.ty.is_fn() {
1026                             Err(EvalError::Unimplemented("unimplemented: mentions of function items".to_string()))
1027                         } else {
1028                             Ok(*self.statics.get(&def_id).expect("static should have been cached (rvalue)"))
1029                         }
1030                     },
1031                     Promoted { index } => Ok(*self.frame().promoted.get(&index).expect("a promoted constant hasn't been precomputed")),
1032                 }
1033             }
1034         }
1035     }
1036
1037     fn eval_lvalue(&mut self, lvalue: &mir::Lvalue<'tcx>) -> EvalResult<Lvalue> {
1038         use rustc::mir::repr::Lvalue::*;
1039         let ptr = match *lvalue {
1040             ReturnPointer => self.frame().return_ptr
1041                 .expect("ReturnPointer used in a function with no return value"),
1042             Arg(i) => self.frame().locals[i as usize],
1043             Var(i) => self.frame().locals[self.frame().var_offset + i as usize],
1044             Temp(i) => self.frame().locals[self.frame().temp_offset + i as usize],
1045
1046             Static(def_id) => *self.gecx.statics.get(&def_id).expect("static should have been cached (lvalue)"),
1047
1048             Projection(ref proj) => {
1049                 let base = self.eval_lvalue(&proj.base)?;
1050                 let base_ty = self.lvalue_ty(&proj.base);
1051                 let base_layout = self.type_layout(base_ty);
1052
1053                 use rustc::mir::repr::ProjectionElem::*;
1054                 match proj.elem {
1055                     Field(field, _) => {
1056                         use rustc::ty::layout::Layout::*;
1057                         let variant = match *base_layout {
1058                             Univariant { ref variant, .. } => variant,
1059                             General { ref variants, .. } => {
1060                                 if let LvalueExtra::DowncastVariant(variant_idx) = base.extra {
1061                                     &variants[variant_idx]
1062                                 } else {
1063                                     panic!("field access on enum had no variant index");
1064                                 }
1065                             }
1066                             RawNullablePointer { .. } => {
1067                                 assert_eq!(field.index(), 0);
1068                                 return Ok(base);
1069                             }
1070                             StructWrappedNullablePointer { ref nonnull, .. } => nonnull,
1071                             _ => panic!("field access on non-product type: {:?}", base_layout),
1072                         };
1073
1074                         let offset = variant.field_offset(field.index()).bytes();
1075                         base.ptr.offset(offset as isize)
1076                     },
1077
1078                     Downcast(_, variant) => {
1079                         use rustc::ty::layout::Layout::*;
1080                         match *base_layout {
1081                             General { discr, .. } => {
1082                                 return Ok(Lvalue {
1083                                     ptr: base.ptr.offset(discr.size().bytes() as isize),
1084                                     extra: LvalueExtra::DowncastVariant(variant),
1085                                 });
1086                             }
1087                             RawNullablePointer { .. } | StructWrappedNullablePointer { .. } => {
1088                                 return Ok(base);
1089                             }
1090                             _ => panic!("variant downcast on non-aggregate: {:?}", base_layout),
1091                         }
1092                     },
1093
1094                     Deref => {
1095                         let pointee_ty = pointee_type(base_ty).expect("Deref of non-pointer");
1096                         let ptr = self.memory.read_ptr(base.ptr)?;
1097                         let extra = match pointee_ty.sty {
1098                             ty::TySlice(_) | ty::TyStr => {
1099                                 let len_ptr = base.ptr.offset(self.memory.pointer_size as isize);
1100                                 let len = self.memory.read_usize(len_ptr)?;
1101                                 LvalueExtra::Length(len)
1102                             }
1103                             ty::TyTrait(_) => unimplemented!(),
1104                             _ => LvalueExtra::None,
1105                         };
1106                         return Ok(Lvalue { ptr: ptr, extra: extra });
1107                     }
1108
1109                     Index(ref operand) => {
1110                         let elem_size = match base_ty.sty {
1111                             ty::TyArray(elem_ty, _) |
1112                             ty::TySlice(elem_ty) => self.type_size(elem_ty),
1113                             _ => panic!("indexing expected an array or slice, got {:?}", base_ty),
1114                         };
1115                         let n_ptr = self.eval_operand(operand)?;
1116                         let n = self.memory.read_usize(n_ptr)?;
1117                         base.ptr.offset(n as isize * elem_size as isize)
1118                     }
1119
1120                     ConstantIndex { .. } => unimplemented!(),
1121                 }
1122             }
1123         };
1124
1125         Ok(Lvalue { ptr: ptr, extra: LvalueExtra::None })
1126     }
1127
1128     // TODO(solson): Try making const_to_primval instead.
1129     fn const_to_ptr(&mut self, const_val: &const_val::ConstVal) -> EvalResult<Pointer> {
1130         use rustc::middle::const_val::ConstVal::*;
1131         match *const_val {
1132             Float(_f) => unimplemented!(),
1133             Integral(int) => {
1134                 // TODO(solson): Check int constant type.
1135                 let ptr = self.memory.allocate(8);
1136                 self.memory.write_uint(ptr, int.to_u64_unchecked(), 8)?;
1137                 Ok(ptr)
1138             }
1139             Str(ref s) => {
1140                 let psize = self.memory.pointer_size;
1141                 let static_ptr = self.memory.allocate(s.len());
1142                 let ptr = self.memory.allocate(psize * 2);
1143                 self.memory.write_bytes(static_ptr, s.as_bytes())?;
1144                 self.memory.write_ptr(ptr, static_ptr)?;
1145                 self.memory.write_usize(ptr.offset(psize as isize), s.len() as u64)?;
1146                 Ok(ptr)
1147             }
1148             ByteStr(ref bs) => {
1149                 let psize = self.memory.pointer_size;
1150                 let static_ptr = self.memory.allocate(bs.len());
1151                 let ptr = self.memory.allocate(psize);
1152                 self.memory.write_bytes(static_ptr, bs)?;
1153                 self.memory.write_ptr(ptr, static_ptr)?;
1154                 Ok(ptr)
1155             }
1156             Bool(b) => {
1157                 let ptr = self.memory.allocate(1);
1158                 self.memory.write_bool(ptr, b)?;
1159                 Ok(ptr)
1160             }
1161             Char(_c)          => unimplemented!(),
1162             Struct(_node_id)  => unimplemented!(),
1163             Tuple(_node_id)   => unimplemented!(),
1164             Function(_def_id) => unimplemented!(),
1165             Array(_, _)       => unimplemented!(),
1166             Repeat(_, _)      => unimplemented!(),
1167             Dummy             => unimplemented!(),
1168         }
1169     }
1170
1171     fn lvalue_ty(&self, lvalue: &mir::Lvalue<'tcx>) -> Ty<'tcx> {
1172         self.monomorphize(self.mir().lvalue_ty(self.tcx, lvalue).to_ty(self.tcx))
1173     }
1174
1175     fn operand_ty(&self, operand: &mir::Operand<'tcx>) -> Ty<'tcx> {
1176         self.monomorphize(self.mir().operand_ty(self.tcx, operand))
1177     }
1178
1179     fn monomorphize(&self, ty: Ty<'tcx>) -> Ty<'tcx> {
1180         let substituted = ty.subst(self.tcx, self.substs());
1181         self.tcx.normalize_associated_type(&substituted)
1182     }
1183
1184     fn type_needs_drop(&self, ty: Ty<'tcx>) -> bool {
1185         self.tcx.type_needs_drop_given_env(ty, &self.tcx.empty_parameter_environment())
1186     }
1187
1188     fn move_(&mut self, src: Pointer, dest: Pointer, ty: Ty<'tcx>) -> EvalResult<()> {
1189         let size = self.type_size(ty);
1190         self.memory.copy(src, dest, size)?;
1191         if self.type_needs_drop(ty) {
1192             self.memory.drop_fill(src, size)?;
1193         }
1194         Ok(())
1195     }
1196
1197     fn type_is_sized(&self, ty: Ty<'tcx>) -> bool {
1198         ty.is_sized(self.tcx, &self.tcx.empty_parameter_environment(), DUMMY_SP)
1199     }
1200
1201     fn type_size(&self, ty: Ty<'tcx>) -> usize {
1202         self.type_layout(ty).size(&self.tcx.data_layout).bytes() as usize
1203     }
1204
1205     fn type_layout(&self, ty: Ty<'tcx>) -> &'tcx Layout {
1206         // TODO(solson): Is this inefficient? Needs investigation.
1207         let ty = self.monomorphize(ty);
1208
1209         self.tcx.normalizing_infer_ctxt(ProjectionMode::Any).enter(|infcx| {
1210             // TODO(solson): Report this error properly.
1211             ty.layout(&infcx).unwrap()
1212         })
1213     }
1214
1215     pub fn read_primval(&mut self, ptr: Pointer, ty: Ty<'tcx>) -> EvalResult<PrimVal> {
1216         use syntax::ast::{IntTy, UintTy};
1217         let val = match (self.memory.pointer_size, &ty.sty) {
1218             (_, &ty::TyBool)              => PrimVal::Bool(self.memory.read_bool(ptr)?),
1219             (_, &ty::TyInt(IntTy::I8))    => PrimVal::I8(self.memory.read_int(ptr, 1)? as i8),
1220             (2, &ty::TyInt(IntTy::Is)) |
1221             (_, &ty::TyInt(IntTy::I16))   => PrimVal::I16(self.memory.read_int(ptr, 2)? as i16),
1222             (4, &ty::TyInt(IntTy::Is)) |
1223             (_, &ty::TyInt(IntTy::I32))   => PrimVal::I32(self.memory.read_int(ptr, 4)? as i32),
1224             (8, &ty::TyInt(IntTy::Is)) |
1225             (_, &ty::TyInt(IntTy::I64))   => PrimVal::I64(self.memory.read_int(ptr, 8)? as i64),
1226             (_, &ty::TyUint(UintTy::U8))  => PrimVal::U8(self.memory.read_uint(ptr, 1)? as u8),
1227             (2, &ty::TyUint(UintTy::Us)) |
1228             (_, &ty::TyUint(UintTy::U16)) => PrimVal::U16(self.memory.read_uint(ptr, 2)? as u16),
1229             (4, &ty::TyUint(UintTy::Us)) |
1230             (_, &ty::TyUint(UintTy::U32)) => PrimVal::U32(self.memory.read_uint(ptr, 4)? as u32),
1231             (8, &ty::TyUint(UintTy::Us)) |
1232             (_, &ty::TyUint(UintTy::U64)) => PrimVal::U64(self.memory.read_uint(ptr, 8)? as u64),
1233
1234             (_, &ty::TyRef(_, ty::TypeAndMut { ty, .. })) |
1235             (_, &ty::TyRawPtr(ty::TypeAndMut { ty, .. })) => {
1236                 if self.type_is_sized(ty) {
1237                     match self.memory.read_ptr(ptr) {
1238                         Ok(p) => PrimVal::AbstractPtr(p),
1239                         Err(EvalError::ReadBytesAsPointer) => {
1240                             PrimVal::IntegerPtr(self.memory.read_usize(ptr)?)
1241                         }
1242                         Err(e) => return Err(e),
1243                     }
1244                 } else {
1245                     return Err(EvalError::Unimplemented(format!("unimplemented: primitive read of fat pointer type: {:?}", ty)));
1246                 }
1247             }
1248
1249             _ => panic!("primitive read of non-primitive type: {:?}", ty),
1250         };
1251         Ok(val)
1252     }
1253
1254     fn frame(&self) -> &Frame<'mir, 'tcx> {
1255         self.stack.last().expect("no call frames exist")
1256     }
1257
1258     fn basic_block(&self) -> &mir::BasicBlockData<'tcx> {
1259         let frame = self.frame();
1260         frame.mir.basic_block_data(frame.next_block)
1261     }
1262
1263     fn frame_mut(&mut self) -> &mut Frame<'mir, 'tcx> {
1264         self.stack.last_mut().expect("no call frames exist")
1265     }
1266
1267     fn mir(&self) -> CachedMir<'mir, 'tcx> {
1268         self.frame().mir.clone()
1269     }
1270
1271     fn substs(&self) -> &'tcx Substs<'tcx> {
1272         self.frame().substs
1273     }
1274
1275     fn load_mir(&self, def_id: DefId) -> CachedMir<'mir, 'tcx> {
1276         match self.tcx.map.as_local_node_id(def_id) {
1277             Some(node_id) => CachedMir::Ref(self.mir_map.map.get(&node_id).unwrap()),
1278             None => {
1279                 let mut mir_cache = self.mir_cache.borrow_mut();
1280                 if let Some(mir) = mir_cache.get(&def_id) {
1281                     return CachedMir::Owned(mir.clone());
1282                 }
1283
1284                 let cs = &self.tcx.sess.cstore;
1285                 let mir = cs.maybe_get_item_mir(self.tcx, def_id).unwrap_or_else(|| {
1286                     panic!("no mir for {:?}", def_id);
1287                 });
1288                 let cached = Rc::new(mir);
1289                 mir_cache.insert(def_id, cached.clone());
1290                 CachedMir::Owned(cached)
1291             }
1292         }
1293     }
1294
1295     fn fulfill_obligation(&self, trait_ref: ty::PolyTraitRef<'tcx>) -> traits::Vtable<'tcx, ()> {
1296         // Do the initial selection for the obligation. This yields the shallow result we are
1297         // looking for -- that is, what specific impl.
1298         self.tcx.normalizing_infer_ctxt(ProjectionMode::Any).enter(|infcx| {
1299             let mut selcx = traits::SelectionContext::new(&infcx);
1300
1301             let obligation = traits::Obligation::new(
1302                 traits::ObligationCause::misc(DUMMY_SP, ast::DUMMY_NODE_ID),
1303                 trait_ref.to_poly_trait_predicate(),
1304             );
1305             let selection = selcx.select(&obligation).unwrap().unwrap();
1306
1307             // Currently, we use a fulfillment context to completely resolve all nested obligations.
1308             // This is because they can inform the inference of the impl's type parameters.
1309             let mut fulfill_cx = traits::FulfillmentContext::new();
1310             let vtable = selection.map(|predicate| {
1311                 fulfill_cx.register_predicate_obligation(&infcx, predicate);
1312             });
1313             infcx.drain_fulfillment_cx_or_panic(DUMMY_SP, &mut fulfill_cx, &vtable)
1314         })
1315     }
1316
1317     /// Trait method, which has to be resolved to an impl method.
1318     pub fn trait_method(
1319         &self,
1320         def_id: DefId,
1321         substs: &'tcx Substs<'tcx>
1322     ) -> (DefId, &'tcx Substs<'tcx>) {
1323         let method_item = self.tcx.impl_or_trait_item(def_id);
1324         let trait_id = method_item.container().id();
1325         let trait_ref = ty::Binder(substs.to_trait_ref(self.tcx, trait_id));
1326         match self.fulfill_obligation(trait_ref) {
1327             traits::VtableImpl(vtable_impl) => {
1328                 let impl_did = vtable_impl.impl_def_id;
1329                 let mname = self.tcx.item_name(def_id);
1330                 // Create a concatenated set of substitutions which includes those from the impl
1331                 // and those from the method:
1332                 let impl_substs = vtable_impl.substs.with_method_from(substs);
1333                 let substs = self.tcx.mk_substs(impl_substs);
1334                 let mth = get_impl_method(self.tcx, impl_did, substs, mname);
1335
1336                 (mth.method.def_id, mth.substs)
1337             }
1338
1339             traits::VtableClosure(vtable_closure) =>
1340                 (vtable_closure.closure_def_id, vtable_closure.substs.func_substs),
1341
1342             traits::VtableFnPointer(_fn_ty) => {
1343                 let _trait_closure_kind = self.tcx.lang_items.fn_trait_kind(trait_id).unwrap();
1344                 unimplemented!()
1345                 // let llfn = trans_fn_pointer_shim(ccx, trait_closure_kind, fn_ty);
1346
1347                 // let method_ty = def_ty(tcx, def_id, substs);
1348                 // let fn_ptr_ty = match method_ty.sty {
1349                 //     ty::TyFnDef(_, _, fty) => tcx.mk_ty(ty::TyFnPtr(fty)),
1350                 //     _ => unreachable!("expected fn item type, found {}",
1351                 //                       method_ty)
1352                 // };
1353                 // Callee::ptr(immediate_rvalue(llfn, fn_ptr_ty))
1354             }
1355
1356             traits::VtableObject(ref _data) => {
1357                 unimplemented!()
1358                 // Callee {
1359                 //     data: Virtual(traits::get_vtable_index_of_object_method(
1360                 //                   tcx, data, def_id)),
1361                 //                   ty: def_ty(tcx, def_id, substs)
1362                 // }
1363             }
1364             vtable => unreachable!("resolved vtable bad vtable {:?} in trans", vtable),
1365         }
1366     }
1367 }
1368
1369 fn pointee_type(ptr_ty: ty::Ty) -> Option<ty::Ty> {
1370     match ptr_ty.sty {
1371         ty::TyRef(_, ty::TypeAndMut { ty, .. }) |
1372         ty::TyRawPtr(ty::TypeAndMut { ty, .. }) |
1373         ty::TyBox(ty) => {
1374             Some(ty)
1375         }
1376         _ => None,
1377     }
1378 }
1379
1380 impl Lvalue {
1381     fn to_ptr(self) -> Pointer {
1382         assert_eq!(self.extra, LvalueExtra::None);
1383         self.ptr
1384     }
1385 }
1386
1387 impl<'mir, 'tcx: 'mir> Deref for CachedMir<'mir, 'tcx> {
1388     type Target = mir::Mir<'tcx>;
1389     fn deref(&self) -> &mir::Mir<'tcx> {
1390         match *self {
1391             CachedMir::Ref(r) => r,
1392             CachedMir::Owned(ref rc) => rc,
1393         }
1394     }
1395 }
1396
1397 #[derive(Debug)]
1398 pub struct ImplMethod<'tcx> {
1399     pub method: Rc<ty::Method<'tcx>>,
1400     pub substs: &'tcx Substs<'tcx>,
1401     pub is_provided: bool,
1402 }
1403
1404 /// Locates the applicable definition of a method, given its name.
1405 pub fn get_impl_method<'a, 'tcx>(
1406     tcx: TyCtxt<'a, 'tcx, 'tcx>,
1407     impl_def_id: DefId,
1408     substs: &'tcx Substs<'tcx>,
1409     name: ast::Name,
1410 ) -> ImplMethod<'tcx> {
1411     assert!(!substs.types.needs_infer());
1412
1413     let trait_def_id = tcx.trait_id_of_impl(impl_def_id).unwrap();
1414     let trait_def = tcx.lookup_trait_def(trait_def_id);
1415
1416     match trait_def.ancestors(impl_def_id).fn_defs(tcx, name).next() {
1417         Some(node_item) => {
1418             let substs = tcx.normalizing_infer_ctxt(ProjectionMode::Any).enter(|infcx| {
1419                 let substs = traits::translate_substs(&infcx, impl_def_id,
1420                                                       substs, node_item.node);
1421                 tcx.lift(&substs).unwrap_or_else(|| {
1422                     bug!("trans::meth::get_impl_method: translate_substs \
1423                           returned {:?} which contains inference types/regions",
1424                          substs);
1425                 })
1426             });
1427             ImplMethod {
1428                 method: node_item.item,
1429                 substs: substs,
1430                 is_provided: node_item.node.is_from_trait(),
1431             }
1432         }
1433         None => {
1434             bug!("method {:?} not found in {:?}", name, impl_def_id)
1435         }
1436     }
1437 }
1438
1439 pub fn interpret_start_points<'a, 'tcx>(
1440     tcx: TyCtxt<'a, 'tcx, 'tcx>,
1441     mir_map: &MirMap<'tcx>,
1442 ) {
1443     let initial_indentation = ::log_settings::settings().indentation;
1444     for (&id, mir) in &mir_map.map {
1445         for attr in tcx.map.attrs(id) {
1446             use syntax::attr::AttrMetaMethods;
1447             if attr.check_name("miri_run") {
1448                 let item = tcx.map.expect_item(id);
1449
1450                 ::log_settings::settings().indentation = initial_indentation;
1451
1452                 debug!("Interpreting: {}", item.name);
1453
1454                 let mut gecx = GlobalEvalContext::new(tcx, mir_map);
1455                 match gecx.call(mir, tcx.map.local_def_id(id)) {
1456                     Ok(Some(return_ptr)) => if log_enabled!(::log::LogLevel::Debug) {
1457                         gecx.memory.dump(return_ptr.alloc_id);
1458                     },
1459                     Ok(None) => warn!("diverging function returned"),
1460                     Err(_e) => {
1461                         // TODO(solson): Detect whether the error was already reported or not.
1462                         // tcx.sess.err(&e.to_string());
1463                     }
1464                 }
1465             }
1466         }
1467     }
1468 }
1469
1470 // TODO(solson): Upstream these methods into rustc::ty::layout.
1471
1472 trait IntegerExt {
1473     fn size(self) -> Size;
1474 }
1475
1476 impl IntegerExt for layout::Integer {
1477     fn size(self) -> Size {
1478         use rustc::ty::layout::Integer::*;
1479         match self {
1480             I1 | I8 => Size::from_bits(8),
1481             I16 => Size::from_bits(16),
1482             I32 => Size::from_bits(32),
1483             I64 => Size::from_bits(64),
1484         }
1485     }
1486 }
1487
1488 trait StructExt {
1489     fn field_offset(&self, index: usize) -> Size;
1490 }
1491
1492 impl StructExt for layout::Struct {
1493     fn field_offset(&self, index: usize) -> Size {
1494         if index == 0 {
1495             Size::from_bytes(0)
1496         } else {
1497             self.offset_after_field[index - 1]
1498         }
1499     }
1500 }