src/librustc_trans/mir/block.rs

   1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use llvm::{self, ValueRef};
  12 use rustc_const_eval::ErrKind;
  13 use rustc::middle::lang_items;
  14 use rustc::ty;
  15 use rustc::mir::repr as mir;
  16 use abi::{Abi, FnType, ArgType};
  17 use adt;
  18 use base;
  19 use build;
  20 use callee::{Callee, CalleeData, Fn, Intrinsic, NamedTupleConstructor, Virtual};
  21 use common::{self, Block, BlockAndBuilder, LandingPad};
  22 use common::{C_bool, C_str_slice, C_struct, C_u32, C_undef};
  23 use consts;
  24 use debuginfo::DebugLoc;
  25 use Disr;
  26 use machine::{llalign_of_min, llbitsize_of_real};
  27 use meth;
  28 use type_of;
  29 use glue;
  30 use type_::Type;
  31
  32 use rustc_data_structures::fnv::FnvHashMap;
  33 use syntax::parse::token;
  34
  35 use super::{MirContext, LocalRef};
  36 use super::analyze::CleanupKind;
  37 use super::constant::Const;
  38 use super::lvalue::{LvalueRef, load_fat_ptr};
  39 use super::operand::OperandRef;
  40 use super::operand::OperandValue::*;
  41
  42 impl<'bcx, 'tcx> MirContext<'bcx, 'tcx> {
  43     pub fn trans_block(&mut self, bb: mir::BasicBlock) {
  44         let mut bcx = self.bcx(bb);
  45         let mir = self.mir.clone();
  46         let data = &mir[bb];
  47
  48         debug!("trans_block({:?}={:?})", bb, data);
  49
  50         // Create the cleanup bundle, if needed.
  51         let cleanup_pad = bcx.lpad().and_then(|lp| lp.cleanuppad());
  52         let cleanup_bundle = bcx.lpad().and_then(|l| l.bundle());
  53
  54         let funclet_br = |this: &Self, bcx: BlockAndBuilder, bb: mir::BasicBlock| {
  55             let lltarget = this.blocks[bb].llbb;
  56             if let Some(cp) = cleanup_pad {
  57                 match this.cleanup_kinds[bb] {
  58                     CleanupKind::Funclet => {
  59                         // micro-optimization: generate a `ret` rather than a jump
  60                         // to a return block
  61                         bcx.cleanup_ret(cp, Some(lltarget));
  62                     }
  63                     CleanupKind::Internal { .. } => bcx.br(lltarget),
  64                     CleanupKind::NotCleanup => bug!("jump from cleanup bb to bb {:?}", bb)
  65                 }
  66             } else {
  67                 bcx.br(lltarget);
  68             }
  69         };
  70
  71         let llblock = |this: &mut Self, target: mir::BasicBlock| {
  72             let lltarget = this.blocks[target].llbb;
  73
  74             if let Some(cp) = cleanup_pad {
  75                 match this.cleanup_kinds[target] {
  76                     CleanupKind::Funclet => {
  77                         // MSVC cross-funclet jump - need a trampoline
  78
  79                         debug!("llblock: creating cleanup trampoline for {:?}", target);
  80                         let name = &format!("{:?}_cleanup_trampoline_{:?}", bb, target);
  81                         let trampoline = this.fcx.new_block(name, None).build();
  82                         trampoline.set_personality_fn(this.fcx.eh_personality());
  83                         trampoline.cleanup_ret(cp, Some(lltarget));
  84                         trampoline.llbb()
  85                     }
  86                     CleanupKind::Internal { .. } => lltarget,
  87                     CleanupKind::NotCleanup =>
  88                         bug!("jump from cleanup bb {:?} to bb {:?}", bb, target)
  89                 }
  90             } else {
  91                 if let (CleanupKind::NotCleanup, CleanupKind::Funclet) =
  92                     (this.cleanup_kinds[bb], this.cleanup_kinds[target])
  93                 {
  94                     // jump *into* cleanup - need a landing pad if GNU
  95                     this.landing_pad_to(target).llbb
  96                 } else {
  97                     lltarget
  98                 }
  99             }
 100         };
 101
 102         for statement in &data.statements {
 103             bcx = self.trans_statement(bcx, statement);
 104         }
 105
 106         let terminator = data.terminator();
 107         debug!("trans_block: terminator: {:?}", terminator);
 108
 109         let span = terminator.source_info.span;
 110         let debug_loc = self.debug_loc(terminator.source_info);
 111         debug_loc.apply_to_bcx(&bcx);
 112         debug_loc.apply(bcx.fcx());
 113         match terminator.kind {
 114             mir::TerminatorKind::Resume => {
 115                 if let Some(cleanup_pad) = cleanup_pad {
 116                     bcx.cleanup_ret(cleanup_pad, None);
 117                 } else {
 118                     let ps = self.get_personality_slot(&bcx);
 119                     let lp = bcx.load(ps);
 120                     bcx.with_block(|bcx| {
 121                         base::call_lifetime_end(bcx, ps);
 122                         base::trans_unwind_resume(bcx, lp);
 123                     });
 124                 }
 125             }
 126
 127             mir::TerminatorKind::Goto { target } => {
 128                 funclet_br(self, bcx, target);
 129             }
 130
 131             mir::TerminatorKind::If { ref cond, targets: (true_bb, false_bb) } => {
 132                 let cond = self.trans_operand(&bcx, cond);
 133
 134                 let lltrue = llblock(self, true_bb);
 135                 let llfalse = llblock(self, false_bb);
 136                 bcx.cond_br(cond.immediate(), lltrue, llfalse);
 137             }
 138
 139             mir::TerminatorKind::Switch { ref discr, ref adt_def, ref targets } => {
 140                 let discr_lvalue = self.trans_lvalue(&bcx, discr);
 141                 let ty = discr_lvalue.ty.to_ty(bcx.tcx());
 142                 let repr = adt::represent_type(bcx.ccx(), ty);
 143                 let discr = bcx.with_block(|bcx|
 144                     adt::trans_get_discr(bcx, &repr, discr_lvalue.llval, None, true)
 145                 );
 146
 147                 let mut bb_hist = FnvHashMap();
 148                 for target in targets {
 149                     *bb_hist.entry(target).or_insert(0) += 1;
 150                 }
 151                 let (default_bb, default_blk) = match bb_hist.iter().max_by_key(|&(_, c)| c) {
 152                     // If a single target basic blocks is predominant, promote that to be the
 153                     // default case for the switch instruction to reduce the size of the generated
 154                     // code. This is especially helpful in cases like an if-let on a huge enum.
 155                     // Note: This optimization is only valid for exhaustive matches.
 156                     Some((&&bb, &c)) if c > targets.len() / 2 => {
 157                         (Some(bb), llblock(self, bb))
 158                     }
 159                     // We're generating an exhaustive switch, so the else branch
 160                     // can't be hit.  Branching to an unreachable instruction
 161                     // lets LLVM know this
 162                     _ => (None, self.unreachable_block().llbb)
 163                 };
 164                 let switch = bcx.switch(discr, default_blk, targets.len());
 165                 assert_eq!(adt_def.variants.len(), targets.len());
 166                 for (adt_variant, &target) in adt_def.variants.iter().zip(targets) {
 167                     if default_bb != Some(target) {
 168                         let llbb = llblock(self, target);
 169                         let llval = bcx.with_block(|bcx| adt::trans_case(
 170                                 bcx, &repr, Disr::from(adt_variant.disr_val)));
 171                         build::AddCase(switch, llval, llbb)
 172                     }
 173                 }
 174             }
 175
 176             mir::TerminatorKind::SwitchInt { ref discr, switch_ty, ref values, ref targets } => {
 177                 let (otherwise, targets) = targets.split_last().unwrap();
 178                 let discr = bcx.load(self.trans_lvalue(&bcx, discr).llval);
 179                 let discr = bcx.with_block(|bcx| base::to_immediate(bcx, discr, switch_ty));
 180                 let switch = bcx.switch(discr, llblock(self, *otherwise), values.len());
 181                 for (value, target) in values.iter().zip(targets) {
 182                     let val = Const::from_constval(bcx.ccx(), value.clone(), switch_ty);
 183                     let llbb = llblock(self, *target);
 184                     build::AddCase(switch, val.llval, llbb)
 185                 }
 186             }
 187
 188             mir::TerminatorKind::Return => {
 189                 let ret = bcx.fcx().fn_ty.ret;
 190                 if ret.is_ignore() || ret.is_indirect() {
 191                     bcx.ret_void();
 192                     return;
 193                 }
 194
 195                 let llval = if let Some(cast_ty) = ret.cast {
 196                     let index = mir.local_index(&mir::Lvalue::ReturnPointer).unwrap();
 197                     let op = match self.locals[index] {
 198                         LocalRef::Operand(Some(op)) => op,
 199                         LocalRef::Operand(None) => bug!("use of return before def"),
 200                         LocalRef::Lvalue(tr_lvalue) => {
 201                             OperandRef {
 202                                 val: Ref(tr_lvalue.llval),
 203                                 ty: tr_lvalue.ty.to_ty(bcx.tcx())
 204                             }
 205                         }
 206                     };
 207                     let llslot = match op.val {
 208                         Immediate(_) | Pair(..) => {
 209                             let llscratch = build::AllocaFcx(bcx.fcx(), ret.original_ty, "ret");
 210                             self.store_operand(&bcx, llscratch, op);
 211                             llscratch
 212                         }
 213                         Ref(llval) => llval
 214                     };
 215                     let load = bcx.load(bcx.pointercast(llslot, cast_ty.ptr_to()));
 216                     let llalign = llalign_of_min(bcx.ccx(), ret.ty);
 217                     unsafe {
 218                         llvm::LLVMSetAlignment(load, llalign);
 219                     }
 220                     load
 221                 } else {
 222                     let op = self.trans_consume(&bcx, &mir::Lvalue::ReturnPointer);
 223                     op.pack_if_pair(&bcx).immediate()
 224                 };
 225                 bcx.ret(llval);
 226             }
 227
 228             mir::TerminatorKind::Unreachable => {
 229                 bcx.unreachable();
 230             }
 231
 232             mir::TerminatorKind::Drop { ref location, target, unwind } => {
 233                 let ty = location.ty(&mir, bcx.tcx()).to_ty(bcx.tcx());
 234                 let ty = bcx.monomorphize(&ty);
 235
 236                 // Double check for necessity to drop
 237                 if !glue::type_needs_drop(bcx.tcx(), ty) {
 238                     funclet_br(self, bcx, target);
 239                     return;
 240                 }
 241
 242                 let lvalue = self.trans_lvalue(&bcx, location);
 243                 let drop_fn = glue::get_drop_glue(bcx.ccx(), ty);
 244                 let drop_ty = glue::get_drop_glue_type(bcx.tcx(), ty);
 245                 let llvalue = if drop_ty != ty {
 246                     bcx.pointercast(lvalue.llval, type_of::type_of(bcx.ccx(), drop_ty).ptr_to())
 247                 } else {
 248                     lvalue.llval
 249                 };
 250                 if let Some(unwind) = unwind {
 251                     bcx.invoke(drop_fn,
 252                                &[llvalue],
 253                                self.blocks[target].llbb,
 254                                llblock(self, unwind),
 255                                cleanup_bundle);
 256                 } else {
 257                     bcx.call(drop_fn, &[llvalue], cleanup_bundle);
 258                     funclet_br(self, bcx, target);
 259                 }
 260             }
 261
 262             mir::TerminatorKind::Assert { ref cond, expected, ref msg, target, cleanup } => {
 263                 let cond = self.trans_operand(&bcx, cond).immediate();
 264                 let mut const_cond = common::const_to_opt_uint(cond).map(|c| c == 1);
 265
 266                 // This case can currently arise only from functions marked
 267                 // with #[rustc_inherit_overflow_checks] and inlined from
 268                 // another crate (mostly core::num generic/#[inline] fns),
 269                 // while the current crate doesn't use overflow checks.
 270                 // NOTE: Unlike binops, negation doesn't have its own
 271                 // checked operation, just a comparison with the minimum
 272                 // value, so we have to check for the assert message.
 273                 if !bcx.ccx().check_overflow() {
 274                     use rustc_const_math::ConstMathErr::Overflow;
 275                     use rustc_const_math::Op::Neg;
 276
 277                     if let mir::AssertMessage::Math(Overflow(Neg)) = *msg {
 278                         const_cond = Some(expected);
 279                     }
 280                 }
 281
 282                 // Don't translate the panic block if success if known.
 283                 if const_cond == Some(expected) {
 284                     funclet_br(self, bcx, target);
 285                     return;
 286                 }
 287
 288                 // Pass the condition through llvm.expect for branch hinting.
 289                 let expect = bcx.ccx().get_intrinsic(&"llvm.expect.i1");
 290                 let cond = bcx.call(expect, &[cond, C_bool(bcx.ccx(), expected)], None);
 291
 292                 // Create the failure block and the conditional branch to it.
 293                 let lltarget = llblock(self, target);
 294                 let panic_block = self.fcx.new_block("panic", None);
 295                 if expected {
 296                     bcx.cond_br(cond, lltarget, panic_block.llbb);
 297                 } else {
 298                     bcx.cond_br(cond, panic_block.llbb, lltarget);
 299                 }
 300
 301                 // After this point, bcx is the block for the call to panic.
 302                 bcx = panic_block.build();
 303                 debug_loc.apply_to_bcx(&bcx);
 304
 305                 // Get the location information.
 306                 let loc = bcx.sess().codemap().lookup_char_pos(span.lo);
 307                 let filename = token::intern_and_get_ident(&loc.file.name);
 308                 let filename = C_str_slice(bcx.ccx(), filename);
 309                 let line = C_u32(bcx.ccx(), loc.line as u32);
 310
 311                 // Put together the arguments to the panic entry point.
 312                 let (lang_item, args, const_err) = match *msg {
 313                     mir::AssertMessage::BoundsCheck { ref len, ref index } => {
 314                         let len = self.trans_operand(&mut bcx, len).immediate();
 315                         let index = self.trans_operand(&mut bcx, index).immediate();
 316
 317                         let const_err = common::const_to_opt_uint(len).and_then(|len| {
 318                             common::const_to_opt_uint(index).map(|index| {
 319                                 ErrKind::IndexOutOfBounds {
 320                                     len: len,
 321                                     index: index
 322                                 }
 323                             })
 324                         });
 325
 326                         let file_line = C_struct(bcx.ccx(), &[filename, line], false);
 327                         let align = llalign_of_min(bcx.ccx(), common::val_ty(file_line));
 328                         let file_line = consts::addr_of(bcx.ccx(),
 329                                                         file_line,
 330                                                         align,
 331                                                         "panic_bounds_check_loc");
 332                         (lang_items::PanicBoundsCheckFnLangItem,
 333                          vec![file_line, index, len],
 334                          const_err)
 335                     }
 336                     mir::AssertMessage::Math(ref err) => {
 337                         let msg_str = token::intern_and_get_ident(err.description());
 338                         let msg_str = C_str_slice(bcx.ccx(), msg_str);
 339                         let msg_file_line = C_struct(bcx.ccx(),
 340                                                      &[msg_str, filename, line],
 341                                                      false);
 342                         let align = llalign_of_min(bcx.ccx(), common::val_ty(msg_file_line));
 343                         let msg_file_line = consts::addr_of(bcx.ccx(),
 344                                                             msg_file_line,
 345                                                             align,
 346                                                             "panic_loc");
 347                         (lang_items::PanicFnLangItem,
 348                          vec![msg_file_line],
 349                          Some(ErrKind::Math(err.clone())))
 350                     }
 351                 };
 352
 353                 // If we know we always panic, and the error message
 354                 // is also constant, then we can produce a warning.
 355                 if const_cond == Some(!expected) {
 356                     if let Some(err) = const_err {
 357                         let _ = consts::const_err(bcx.ccx(), span,
 358                                                   Err::<(), _>(err),
 359                                                   consts::TrueConst::No);
 360                     }
 361                 }
 362
 363                 // Obtain the panic entry point.
 364                 let def_id = common::langcall(bcx.tcx(), Some(span), "", lang_item);
 365                 let callee = Callee::def(bcx.ccx(), def_id,
 366                     bcx.ccx().empty_substs_for_def_id(def_id));
 367                 let llfn = callee.reify(bcx.ccx()).val;
 368
 369                 // Translate the actual panic invoke/call.
 370                 if let Some(unwind) = cleanup {
 371                     bcx.invoke(llfn,
 372                                &args,
 373                                self.unreachable_block().llbb,
 374                                llblock(self, unwind),
 375                                cleanup_bundle);
 376                 } else {
 377                     bcx.call(llfn, &args, cleanup_bundle);
 378                     bcx.unreachable();
 379                 }
 380             }
 381
 382             mir::TerminatorKind::DropAndReplace { .. } => {
 383                 bug!("undesugared DropAndReplace in trans: {:?}", data);
 384             }
 385
 386             mir::TerminatorKind::Call { ref func, ref args, ref destination, ref cleanup } => {
 387                 // Create the callee. This is a fn ptr or zero-sized and hence a kind of scalar.
 388                 let callee = self.trans_operand(&bcx, func);
 389
 390                 let (mut callee, abi, sig) = match callee.ty.sty {
 391                     ty::TyFnDef(def_id, substs, f) => {
 392                         (Callee::def(bcx.ccx(), def_id, substs), f.abi, &f.sig)
 393                     }
 394                     ty::TyFnPtr(f) => {
 395                         (Callee {
 396                             data: Fn(callee.immediate()),
 397                             ty: callee.ty
 398                         }, f.abi, &f.sig)
 399                     }
 400                     _ => bug!("{} is not callable", callee.ty)
 401                 };
 402
 403                 let sig = bcx.tcx().erase_late_bound_regions(sig);
 404
 405                 // Handle intrinsics old trans wants Expr's for, ourselves.
 406                 let intrinsic = match (&callee.ty.sty, &callee.data) {
 407                     (&ty::TyFnDef(def_id, _, _), &Intrinsic) => {
 408                         Some(bcx.tcx().item_name(def_id).as_str())
 409                     }
 410                     _ => None
 411                 };
 412                 let intrinsic = intrinsic.as_ref().map(|s| &s[..]);
 413
 414                 if intrinsic == Some("move_val_init") {
 415                     let &(_, target) = destination.as_ref().unwrap();
 416                     // The first argument is a thin destination pointer.
 417                     let llptr = self.trans_operand(&bcx, &args[0]).immediate();
 418                     let val = self.trans_operand(&bcx, &args[1]);
 419                     self.store_operand(&bcx, llptr, val);
 420                     funclet_br(self, bcx, target);
 421                     return;
 422                 }
 423
 424                 if intrinsic == Some("transmute") {
 425                     let &(ref dest, target) = destination.as_ref().unwrap();
 426                     self.with_lvalue_ref(&bcx, dest, |this, dest| {
 427                         this.trans_transmute(&bcx, &args[0], dest);
 428                     });
 429
 430                     funclet_br(self, bcx, target);
 431                     return;
 432                 }
 433
 434                 let extra_args = &args[sig.inputs.len()..];
 435                 let extra_args = extra_args.iter().map(|op_arg| {
 436                     let op_ty = op_arg.ty(&self.mir, bcx.tcx());
 437                     bcx.monomorphize(&op_ty)
 438                 }).collect::<Vec<_>>();
 439                 let fn_ty = callee.direct_fn_type(bcx.ccx(), &extra_args);
 440
 441                 // The arguments we'll be passing. Plus one to account for outptr, if used.
 442                 let arg_count = fn_ty.args.len() + fn_ty.ret.is_indirect() as usize;
 443                 let mut llargs = Vec::with_capacity(arg_count);
 444
 445                 // Prepare the return value destination
 446                 let ret_dest = if let Some((ref dest, _)) = *destination {
 447                     let is_intrinsic = if let Intrinsic = callee.data {
 448                         true
 449                     } else {
 450                         false
 451                     };
 452                     self.make_return_dest(&bcx, dest, &fn_ty.ret, &mut llargs, is_intrinsic)
 453                 } else {
 454                     ReturnDest::Nothing
 455                 };
 456
 457                 // Split the rust-call tupled arguments off.
 458                 let (first_args, untuple) = if abi == Abi::RustCall && !args.is_empty() {
 459                     let (tup, args) = args.split_last().unwrap();
 460                     (args, Some(tup))
 461                 } else {
 462                     (&args[..], None)
 463                 };
 464
 465                 let is_shuffle = intrinsic.map_or(false, |name| {
 466                     name.starts_with("simd_shuffle")
 467                 });
 468                 let mut idx = 0;
 469                 for arg in first_args {
 470                     // The indices passed to simd_shuffle* in the
 471                     // third argument must be constant. This is
 472                     // checked by const-qualification, which also
 473                     // promotes any complex rvalues to constants.
 474                     if is_shuffle && idx == 2 {
 475                         match *arg {
 476                             mir::Operand::Consume(_) => {
 477                                 span_bug!(span, "shuffle indices must be constant");
 478                             }
 479                             mir::Operand::Constant(ref constant) => {
 480                                 let val = self.trans_constant(&bcx, constant);
 481                                 llargs.push(val.llval);
 482                                 idx += 1;
 483                                 continue;
 484                             }
 485                         }
 486                     }
 487
 488                     let op = self.trans_operand(&bcx, arg);
 489                     self.trans_argument(&bcx, op, &mut llargs, &fn_ty,
 490                                         &mut idx, &mut callee.data);
 491                 }
 492                 if let Some(tup) = untuple {
 493                     self.trans_arguments_untupled(&bcx, tup, &mut llargs, &fn_ty,
 494                                                   &mut idx, &mut callee.data)
 495                 }
 496
 497                 let fn_ptr = match callee.data {
 498                     NamedTupleConstructor(_) => {
 499                         // FIXME translate this like mir::Rvalue::Aggregate.
 500                         callee.reify(bcx.ccx()).val
 501                     }
 502                     Intrinsic => {
 503                         use callee::ArgVals;
 504                         use expr::{Ignore, SaveIn};
 505                         use intrinsic::trans_intrinsic_call;
 506
 507                         let (dest, llargs) = match ret_dest {
 508                             _ if fn_ty.ret.is_indirect() => {
 509                                 (SaveIn(llargs[0]), &llargs[1..])
 510                             }
 511                             ReturnDest::Nothing => (Ignore, &llargs[..]),
 512                             ReturnDest::IndirectOperand(dst, _) |
 513                             ReturnDest::Store(dst) => (SaveIn(dst), &llargs[..]),
 514                             ReturnDest::DirectOperand(_) =>
 515                                 bug!("Cannot use direct operand with an intrinsic call")
 516                         };
 517
 518                         bcx.with_block(|bcx| {
 519                             trans_intrinsic_call(bcx, callee.ty, &fn_ty,
 520                                                            ArgVals(llargs), dest,
 521                                                            debug_loc);
 522                         });
 523
 524                         if let ReturnDest::IndirectOperand(dst, _) = ret_dest {
 525                             // Make a fake operand for store_return
 526                             let op = OperandRef {
 527                                 val: Ref(dst),
 528                                 ty: sig.output,
 529                             };
 530                             self.store_return(&bcx, ret_dest, fn_ty.ret, op);
 531                         }
 532
 533                         if let Some((_, target)) = *destination {
 534                             funclet_br(self, bcx, target);
 535                         } else {
 536                             // trans_intrinsic_call already used Unreachable.
 537                             // bcx.unreachable();
 538                         }
 539
 540                         return;
 541                     }
 542                     Fn(f) => f,
 543                     Virtual(_) => bug!("Virtual fn ptr not extracted")
 544                 };
 545
 546                 // Many different ways to call a function handled here
 547                 if let &Some(cleanup) = cleanup {
 548                     let ret_bcx = if let Some((_, target)) = *destination {
 549                         self.blocks[target]
 550                     } else {
 551                         self.unreachable_block()
 552                     };
 553                     let invokeret = bcx.invoke(fn_ptr,
 554                                                &llargs,
 555                                                ret_bcx.llbb,
 556                                                llblock(self, cleanup),
 557                                                cleanup_bundle);
 558                     fn_ty.apply_attrs_callsite(invokeret);
 559
 560                     if destination.is_some() {
 561                         let ret_bcx = ret_bcx.build();
 562                         ret_bcx.at_start(|ret_bcx| {
 563                             debug_loc.apply_to_bcx(ret_bcx);
 564                             let op = OperandRef {
 565                                 val: Immediate(invokeret),
 566                                 ty: sig.output,
 567                             };
 568                             self.store_return(&ret_bcx, ret_dest, fn_ty.ret, op);
 569                         });
 570                     }
 571                 } else {
 572                     let llret = bcx.call(fn_ptr, &llargs, cleanup_bundle);
 573                     fn_ty.apply_attrs_callsite(llret);
 574                     if let Some((_, target)) = *destination {
 575                         let op = OperandRef {
 576                             val: Immediate(llret),
 577                             ty: sig.output,
 578                         };
 579                         self.store_return(&bcx, ret_dest, fn_ty.ret, op);
 580                         funclet_br(self, bcx, target);
 581                     } else {
 582                         bcx.unreachable();
 583                     }
 584                 }
 585             }
 586         }
 587     }
 588
 589     fn trans_argument(&mut self,
 590                       bcx: &BlockAndBuilder<'bcx, 'tcx>,
 591                       op: OperandRef<'tcx>,
 592                       llargs: &mut Vec<ValueRef>,
 593                       fn_ty: &FnType,
 594                       next_idx: &mut usize,
 595                       callee: &mut CalleeData) {
 596         if let Pair(a, b) = op.val {
 597             // Treat the values in a fat pointer separately.
 598             if common::type_is_fat_ptr(bcx.tcx(), op.ty) {
 599                 let (ptr, meta) = (a, b);
 600                 if *next_idx == 0 {
 601                     if let Virtual(idx) = *callee {
 602                         let llfn = bcx.with_block(|bcx| {
 603                             meth::get_virtual_method(bcx, meta, idx)
 604                         });
 605                         let llty = fn_ty.llvm_type(bcx.ccx()).ptr_to();
 606                         *callee = Fn(bcx.pointercast(llfn, llty));
 607                     }
 608                 }
 609
 610                 let imm_op = |x| OperandRef {
 611                     val: Immediate(x),
 612                     // We won't be checking the type again.
 613                     ty: bcx.tcx().types.err
 614                 };
 615                 self.trans_argument(bcx, imm_op(ptr), llargs, fn_ty, next_idx, callee);
 616                 self.trans_argument(bcx, imm_op(meta), llargs, fn_ty, next_idx, callee);
 617                 return;
 618             }
 619         }
 620
 621         let arg = &fn_ty.args[*next_idx];
 622         *next_idx += 1;
 623
 624         // Fill padding with undef value, where applicable.
 625         if let Some(ty) = arg.pad {
 626             llargs.push(C_undef(ty));
 627         }
 628
 629         if arg.is_ignore() {
 630             return;
 631         }
 632
 633         // Force by-ref if we have to load through a cast pointer.
 634         let (mut llval, by_ref) = match op.val {
 635             Immediate(_) | Pair(..) => {
 636                 if arg.is_indirect() || arg.cast.is_some() {
 637                     let llscratch = build::AllocaFcx(bcx.fcx(), arg.original_ty, "arg");
 638                     self.store_operand(bcx, llscratch, op);
 639                     (llscratch, true)
 640                 } else {
 641                     (op.pack_if_pair(bcx).immediate(), false)
 642                 }
 643             }
 644             Ref(llval) => (llval, true)
 645         };
 646
 647         if by_ref && !arg.is_indirect() {
 648             // Have to load the argument, maybe while casting it.
 649             if arg.original_ty == Type::i1(bcx.ccx()) {
 650                 // We store bools as i8 so we need to truncate to i1.
 651                 llval = bcx.load_range_assert(llval, 0, 2, llvm::False);
 652                 llval = bcx.trunc(llval, arg.original_ty);
 653             } else if let Some(ty) = arg.cast {
 654                 llval = bcx.load(bcx.pointercast(llval, ty.ptr_to()));
 655                 let llalign = llalign_of_min(bcx.ccx(), arg.ty);
 656                 unsafe {
 657                     llvm::LLVMSetAlignment(llval, llalign);
 658                 }
 659             } else {
 660                 llval = bcx.load(llval);
 661             }
 662         }
 663
 664         llargs.push(llval);
 665     }
 666
 667     fn trans_arguments_untupled(&mut self,
 668                                 bcx: &BlockAndBuilder<'bcx, 'tcx>,
 669                                 operand: &mir::Operand<'tcx>,
 670                                 llargs: &mut Vec<ValueRef>,
 671                                 fn_ty: &FnType,
 672                                 next_idx: &mut usize,
 673                                 callee: &mut CalleeData) {
 674         let tuple = self.trans_operand(bcx, operand);
 675
 676         let arg_types = match tuple.ty.sty {
 677             ty::TyTuple(ref tys) => tys,
 678             _ => span_bug!(self.mir.span,
 679                            "bad final argument to \"rust-call\" fn {:?}", tuple.ty)
 680         };
 681
 682         // Handle both by-ref and immediate tuples.
 683         match tuple.val {
 684             Ref(llval) => {
 685                 let base_repr = adt::represent_type(bcx.ccx(), tuple.ty);
 686                 let base = adt::MaybeSizedValue::sized(llval);
 687                 for (n, &ty) in arg_types.iter().enumerate() {
 688                     let ptr = adt::trans_field_ptr_builder(bcx, &base_repr, base, Disr(0), n);
 689                     let val = if common::type_is_fat_ptr(bcx.tcx(), ty) {
 690                         let (lldata, llextra) = load_fat_ptr(bcx, ptr);
 691                         Pair(lldata, llextra)
 692                     } else {
 693                         // trans_argument will load this if it needs to
 694                         Ref(ptr)
 695                     };
 696                     let op = OperandRef {
 697                         val: val,
 698                         ty: ty
 699                     };
 700                     self.trans_argument(bcx, op, llargs, fn_ty, next_idx, callee);
 701                 }
 702
 703             }
 704             Immediate(llval) => {
 705                 for (n, &ty) in arg_types.iter().enumerate() {
 706                     let mut elem = bcx.extract_value(llval, n);
 707                     // Truncate bools to i1, if needed
 708                     if ty.is_bool() && common::val_ty(elem) != Type::i1(bcx.ccx()) {
 709                         elem = bcx.trunc(elem, Type::i1(bcx.ccx()));
 710                     }
 711                     // If the tuple is immediate, the elements are as well
 712                     let op = OperandRef {
 713                         val: Immediate(elem),
 714                         ty: ty
 715                     };
 716                     self.trans_argument(bcx, op, llargs, fn_ty, next_idx, callee);
 717                 }
 718             }
 719             Pair(a, b) => {
 720                 let elems = [a, b];
 721                 for (n, &ty) in arg_types.iter().enumerate() {
 722                     let mut elem = elems[n];
 723                     // Truncate bools to i1, if needed
 724                     if ty.is_bool() && common::val_ty(elem) != Type::i1(bcx.ccx()) {
 725                         elem = bcx.trunc(elem, Type::i1(bcx.ccx()));
 726                     }
 727                     // Pair is always made up of immediates
 728                     let op = OperandRef {
 729                         val: Immediate(elem),
 730                         ty: ty
 731                     };
 732                     self.trans_argument(bcx, op, llargs, fn_ty, next_idx, callee);
 733                 }
 734             }
 735         }
 736
 737     }
 738
 739     fn get_personality_slot(&mut self, bcx: &BlockAndBuilder<'bcx, 'tcx>) -> ValueRef {
 740         let ccx = bcx.ccx();
 741         if let Some(slot) = self.llpersonalityslot {
 742             slot
 743         } else {
 744             let llretty = Type::struct_(ccx, &[Type::i8p(ccx), Type::i32(ccx)], false);
 745             bcx.with_block(|bcx| {
 746                 let slot = base::alloca(bcx, llretty, "personalityslot");
 747                 self.llpersonalityslot = Some(slot);
 748                 base::call_lifetime_start(bcx, slot);
 749                 slot
 750             })
 751         }
 752     }
 753
 754     /// Return the landingpad wrapper around the given basic block
 755     ///
 756     /// No-op in MSVC SEH scheme.
 757     fn landing_pad_to(&mut self, target_bb: mir::BasicBlock) -> Block<'bcx, 'tcx>
 758     {
 759         if let Some(block) = self.landing_pads[target_bb] {
 760             return block;
 761         }
 762
 763         if base::wants_msvc_seh(self.fcx.ccx.sess()) {
 764             return self.blocks[target_bb];
 765         }
 766
 767         let target = self.bcx(target_bb);
 768
 769         let block = self.fcx.new_block("cleanup", None);
 770         self.landing_pads[target_bb] = Some(block);
 771
 772         let bcx = block.build();
 773         let ccx = bcx.ccx();
 774         let llpersonality = self.fcx.eh_personality();
 775         let llretty = Type::struct_(ccx, &[Type::i8p(ccx), Type::i32(ccx)], false);
 776         let llretval = bcx.landing_pad(llretty, llpersonality, 1, self.fcx.llfn);
 777         bcx.set_cleanup(llretval);
 778         let slot = self.get_personality_slot(&bcx);
 779         bcx.store(llretval, slot);
 780         bcx.br(target.llbb());
 781         block
 782     }
 783
 784     pub fn init_cpad(&mut self, bb: mir::BasicBlock) {
 785         let bcx = self.bcx(bb);
 786         let data = &self.mir[bb];
 787         debug!("init_cpad({:?})", data);
 788
 789         match self.cleanup_kinds[bb] {
 790             CleanupKind::NotCleanup => {
 791                 bcx.set_lpad(None)
 792             }
 793             _ if !base::wants_msvc_seh(bcx.sess()) => {
 794                 bcx.set_lpad(Some(LandingPad::gnu()))
 795             }
 796             CleanupKind::Internal { funclet } => {
 797                 // FIXME: is this needed?
 798                 bcx.set_personality_fn(self.fcx.eh_personality());
 799                 bcx.set_lpad_ref(self.bcx(funclet).lpad());
 800             }
 801             CleanupKind::Funclet => {
 802                 bcx.set_personality_fn(self.fcx.eh_personality());
 803                 DebugLoc::None.apply_to_bcx(&bcx);
 804                 let cleanup_pad = bcx.cleanup_pad(None, &[]);
 805                 bcx.set_lpad(Some(LandingPad::msvc(cleanup_pad)));
 806             }
 807         };
 808     }
 809
 810     fn unreachable_block(&mut self) -> Block<'bcx, 'tcx> {
 811         self.unreachable_block.unwrap_or_else(|| {
 812             let bl = self.fcx.new_block("unreachable", None);
 813             bl.build().unreachable();
 814             self.unreachable_block = Some(bl);
 815             bl
 816         })
 817     }
 818
 819     fn bcx(&self, bb: mir::BasicBlock) -> BlockAndBuilder<'bcx, 'tcx> {
 820         self.blocks[bb].build()
 821     }
 822
 823     fn make_return_dest(&mut self, bcx: &BlockAndBuilder<'bcx, 'tcx>,
 824                         dest: &mir::Lvalue<'tcx>, fn_ret_ty: &ArgType,
 825                         llargs: &mut Vec<ValueRef>, is_intrinsic: bool) -> ReturnDest {
 826         // If the return is ignored, we can just return a do-nothing ReturnDest
 827         if fn_ret_ty.is_ignore() {
 828             return ReturnDest::Nothing;
 829         }
 830         let dest = if let Some(index) = self.mir.local_index(dest) {
 831             let ret_ty = self.monomorphized_lvalue_ty(dest);
 832             match self.locals[index] {
 833                 LocalRef::Lvalue(dest) => dest,
 834                 LocalRef::Operand(None) => {
 835                     // Handle temporary lvalues, specifically Operand ones, as
 836                     // they don't have allocas
 837                     return if fn_ret_ty.is_indirect() {
 838                         // Odd, but possible, case, we have an operand temporary,
 839                         // but the calling convention has an indirect return.
 840                         let tmp = bcx.with_block(|bcx| {
 841                             base::alloc_ty(bcx, ret_ty, "tmp_ret")
 842                         });
 843                         llargs.push(tmp);
 844                         ReturnDest::IndirectOperand(tmp, index)
 845                     } else if is_intrinsic {
 846                         // Currently, intrinsics always need a location to store
 847                         // the result. so we create a temporary alloca for the
 848                         // result
 849                         let tmp = bcx.with_block(|bcx| {
 850                             base::alloc_ty(bcx, ret_ty, "tmp_ret")
 851                         });
 852                         ReturnDest::IndirectOperand(tmp, index)
 853                     } else {
 854                         ReturnDest::DirectOperand(index)
 855                     };
 856                 }
 857                 LocalRef::Operand(Some(_)) => {
 858                     bug!("lvalue local already assigned to");
 859                 }
 860             }
 861         } else {
 862             self.trans_lvalue(bcx, dest)
 863         };
 864         if fn_ret_ty.is_indirect() {
 865             llargs.push(dest.llval);
 866             ReturnDest::Nothing
 867         } else {
 868             ReturnDest::Store(dest.llval)
 869         }
 870     }
 871
 872     fn trans_transmute(&mut self, bcx: &BlockAndBuilder<'bcx, 'tcx>,
 873                        src: &mir::Operand<'tcx>, dst: LvalueRef<'tcx>) {
 874         let mut val = self.trans_operand(bcx, src);
 875         if let ty::TyFnDef(def_id, substs, _) = val.ty.sty {
 876             let llouttype = type_of::type_of(bcx.ccx(), dst.ty.to_ty(bcx.tcx()));
 877             let out_type_size = llbitsize_of_real(bcx.ccx(), llouttype);
 878             if out_type_size != 0 {
 879                 // FIXME #19925 Remove this hack after a release cycle.
 880                 let f = Callee::def(bcx.ccx(), def_id, substs);
 881                 let datum = f.reify(bcx.ccx());
 882                 val = OperandRef {
 883                     val: Immediate(datum.val),
 884                     ty: datum.ty
 885                 };
 886             }
 887         }
 888
 889         let llty = type_of::type_of(bcx.ccx(), val.ty);
 890         let cast_ptr = bcx.pointercast(dst.llval, llty.ptr_to());
 891         self.store_operand(bcx, cast_ptr, val);
 892     }
 893
 894
 895     // Stores the return value of a function call into it's final location.
 896     fn store_return(&mut self,
 897                     bcx: &BlockAndBuilder<'bcx, 'tcx>,
 898                     dest: ReturnDest,
 899                     ret_ty: ArgType,
 900                     op: OperandRef<'tcx>) {
 901         use self::ReturnDest::*;
 902
 903         match dest {
 904             Nothing => (),
 905             Store(dst) => ret_ty.store(bcx, op.immediate(), dst),
 906             IndirectOperand(tmp, index) => {
 907                 let op = self.trans_load(bcx, tmp, op.ty);
 908                 self.locals[index] = LocalRef::Operand(Some(op));
 909             }
 910             DirectOperand(index) => {
 911                 // If there is a cast, we have to store and reload.
 912                 let op = if ret_ty.cast.is_some() {
 913                     let tmp = bcx.with_block(|bcx| {
 914                         base::alloc_ty(bcx, op.ty, "tmp_ret")
 915                     });
 916                     ret_ty.store(bcx, op.immediate(), tmp);
 917                     self.trans_load(bcx, tmp, op.ty)
 918                 } else {
 919                     op.unpack_if_pair(bcx)
 920                 };
 921                 self.locals[index] = LocalRef::Operand(Some(op));
 922             }
 923         }
 924     }
 925 }
 926
 927 enum ReturnDest {
 928     // Do nothing, the return value is indirect or ignored
 929     Nothing,
 930     // Store the return value to the pointer
 931     Store(ValueRef),
 932     // Stores an indirect return value to an operand local lvalue
 933     IndirectOperand(ValueRef, mir::Local),
 934     // Stores a direct return value to an operand local lvalue
 935     DirectOperand(mir::Local)
 936 }