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, BasicBlockRef};
  12 use rustc_const_eval::{ErrKind, ConstEvalErr, note_const_eval_err};
  13 use rustc::middle::lang_items;
  14 use rustc::ty::{self, layout, TypeFoldable};
  15 use rustc::mir;
  16 use abi::{Abi, FnType, ArgType};
  17 use adt;
  18 use base::{self, Lifetime};
  19 use callee::{Callee, CalleeData, Fn, Intrinsic, NamedTupleConstructor, Virtual};
  20 use builder::Builder;
  21 use common::{self, Funclet};
  22 use common::{C_bool, C_str_slice, C_struct, C_u32, C_undef};
  23 use consts;
  24 use Disr;
  25 use machine::{llalign_of_min, llbitsize_of_real};
  26 use meth;
  27 use type_of::{self, align_of};
  28 use glue;
  29 use type_::Type;
  30
  31 use rustc_data_structures::indexed_vec::IndexVec;
  32 use rustc_data_structures::fx::FxHashMap;
  33 use syntax::symbol::Symbol;
  34
  35 use std::cmp;
  36
  37 use super::{MirContext, LocalRef};
  38 use super::analyze::CleanupKind;
  39 use super::constant::Const;
  40 use super::lvalue::{Alignment, LvalueRef};
  41 use super::operand::OperandRef;
  42 use super::operand::OperandValue::{Pair, Ref, Immediate};
  43
  44 impl<'a, 'tcx> MirContext<'a, 'tcx> {
  45     pub fn trans_block(&mut self, bb: mir::BasicBlock,
  46         funclets: &IndexVec<mir::BasicBlock, Option<Funclet>>) {
  47         let mut bcx = self.get_builder(bb);
  48         let data = &self.mir[bb];
  49
  50         debug!("trans_block({:?}={:?})", bb, data);
  51
  52         let funclet = match self.cleanup_kinds[bb] {
  53             CleanupKind::Internal { funclet } => funclets[funclet].as_ref(),
  54             _ => funclets[bb].as_ref(),
  55         };
  56
  57         // Create the cleanup bundle, if needed.
  58         let cleanup_pad = funclet.map(|lp| lp.cleanuppad());
  59         let cleanup_bundle = funclet.map(|l| l.bundle());
  60
  61         let funclet_br = |this: &Self, bcx: Builder, bb: mir::BasicBlock| {
  62             let lltarget = this.blocks[bb];
  63             if let Some(cp) = cleanup_pad {
  64                 match this.cleanup_kinds[bb] {
  65                     CleanupKind::Funclet => {
  66                         // micro-optimization: generate a `ret` rather than a jump
  67                         // to a return block
  68                         bcx.cleanup_ret(cp, Some(lltarget));
  69                     }
  70                     CleanupKind::Internal { .. } => bcx.br(lltarget),
  71                     CleanupKind::NotCleanup => bug!("jump from cleanup bb to bb {:?}", bb)
  72                 }
  73             } else {
  74                 bcx.br(lltarget);
  75             }
  76         };
  77
  78         let llblock = |this: &mut Self, target: mir::BasicBlock| {
  79             let lltarget = this.blocks[target];
  80
  81             if let Some(cp) = cleanup_pad {
  82                 match this.cleanup_kinds[target] {
  83                     CleanupKind::Funclet => {
  84                         // MSVC cross-funclet jump - need a trampoline
  85
  86                         debug!("llblock: creating cleanup trampoline for {:?}", target);
  87                         let name = &format!("{:?}_cleanup_trampoline_{:?}", bb, target);
  88                         let trampoline = this.new_block(name);
  89                         trampoline.cleanup_ret(cp, Some(lltarget));
  90                         trampoline.llbb()
  91                     }
  92                     CleanupKind::Internal { .. } => lltarget,
  93                     CleanupKind::NotCleanup =>
  94                         bug!("jump from cleanup bb {:?} to bb {:?}", bb, target)
  95                 }
  96             } else {
  97                 if let (CleanupKind::NotCleanup, CleanupKind::Funclet) =
  98                     (this.cleanup_kinds[bb], this.cleanup_kinds[target])
  99                 {
 100                     // jump *into* cleanup - need a landing pad if GNU
 101                     this.landing_pad_to(target)
 102                 } else {
 103                     lltarget
 104                 }
 105             }
 106         };
 107
 108         for statement in &data.statements {
 109             bcx = self.trans_statement(bcx, statement);
 110         }
 111
 112         let terminator = data.terminator();
 113         debug!("trans_block: terminator: {:?}", terminator);
 114
 115         let span = terminator.source_info.span;
 116         self.set_debug_loc(&bcx, terminator.source_info);
 117         match terminator.kind {
 118             mir::TerminatorKind::Resume => {
 119                 if let Some(cleanup_pad) = cleanup_pad {
 120                     bcx.cleanup_ret(cleanup_pad, None);
 121                 } else {
 122                     let ps = self.get_personality_slot(&bcx);
 123                     let lp = bcx.load(ps, None);
 124                     Lifetime::End.call(&bcx, ps);
 125                     if !bcx.sess().target.target.options.custom_unwind_resume {
 126                         bcx.resume(lp);
 127                     } else {
 128                         let exc_ptr = bcx.extract_value(lp, 0);
 129                         bcx.call(bcx.ccx.eh_unwind_resume(), &[exc_ptr], cleanup_bundle);
 130                         bcx.unreachable();
 131                     }
 132                 }
 133             }
 134
 135             mir::TerminatorKind::Goto { target } => {
 136                 funclet_br(self, bcx, target);
 137             }
 138
 139             mir::TerminatorKind::If { ref cond, targets: (true_bb, false_bb) } => {
 140                 let cond = self.trans_operand(&bcx, cond);
 141
 142                 let lltrue = llblock(self, true_bb);
 143                 let llfalse = llblock(self, false_bb);
 144                 bcx.cond_br(cond.immediate(), lltrue, llfalse);
 145             }
 146
 147             mir::TerminatorKind::Switch { ref discr, ref adt_def, ref targets } => {
 148                 let discr_lvalue = self.trans_lvalue(&bcx, discr);
 149                 let ty = discr_lvalue.ty.to_ty(bcx.tcx());
 150                 let discr = adt::trans_get_discr(
 151                     &bcx, ty, discr_lvalue.llval, discr_lvalue.alignment,
 152                     None, true);
 153
 154                 let mut bb_hist = FxHashMap();
 155                 for target in targets {
 156                     *bb_hist.entry(target).or_insert(0) += 1;
 157                 }
 158                 let (default_bb, default_blk) = match bb_hist.iter().max_by_key(|&(_, c)| c) {
 159                     // If a single target basic blocks is predominant, promote that to be the
 160                     // default case for the switch instruction to reduce the size of the generated
 161                     // code. This is especially helpful in cases like an if-let on a huge enum.
 162                     // Note: This optimization is only valid for exhaustive matches.
 163                     Some((&&bb, &c)) if c > targets.len() / 2 => {
 164                         (Some(bb), llblock(self, bb))
 165                     }
 166                     // We're generating an exhaustive switch, so the else branch
 167                     // can't be hit.  Branching to an unreachable instruction
 168                     // lets LLVM know this
 169                     _ => (None, self.unreachable_block())
 170                 };
 171                 let switch = bcx.switch(discr, default_blk, targets.len());
 172                 assert_eq!(adt_def.variants.len(), targets.len());
 173                 for (adt_variant, &target) in adt_def.variants.iter().zip(targets) {
 174                     if default_bb != Some(target) {
 175                         let llbb = llblock(self, target);
 176                         let llval = adt::trans_case(&bcx, ty, Disr::from(adt_variant.disr_val));
 177                         bcx.add_case(switch, llval, llbb)
 178                     }
 179                 }
 180             }
 181
 182             mir::TerminatorKind::SwitchInt { ref discr, switch_ty, ref values, ref targets } => {
 183                 let (otherwise, targets) = targets.split_last().unwrap();
 184                 let lv = self.trans_lvalue(&bcx, discr);
 185                 let discr = bcx.load(lv.llval, lv.alignment.to_align());
 186                 let discr = base::to_immediate(&bcx, discr, switch_ty);
 187                 let switch = bcx.switch(discr, llblock(self, *otherwise), values.len());
 188                 for (value, target) in values.iter().zip(targets) {
 189                     let val = Const::from_constval(bcx.ccx, value.clone(), switch_ty);
 190                     let llbb = llblock(self, *target);
 191                     bcx.add_case(switch, val.llval, llbb)
 192                 }
 193             }
 194
 195             mir::TerminatorKind::Return => {
 196                 let ret = self.fn_ty.ret;
 197                 if ret.is_ignore() || ret.is_indirect() {
 198                     bcx.ret_void();
 199                     return;
 200                 }
 201
 202                 let llval = if let Some(cast_ty) = ret.cast {
 203                     let op = match self.locals[mir::RETURN_POINTER] {
 204                         LocalRef::Operand(Some(op)) => op,
 205                         LocalRef::Operand(None) => bug!("use of return before def"),
 206                         LocalRef::Lvalue(tr_lvalue) => {
 207                             OperandRef {
 208                                 val: Ref(tr_lvalue.llval, tr_lvalue.alignment),
 209                                 ty: tr_lvalue.ty.to_ty(bcx.tcx())
 210                             }
 211                         }
 212                     };
 213                     let llslot = match op.val {
 214                         Immediate(_) | Pair(..) => {
 215                             let llscratch = bcx.alloca(ret.original_ty, "ret");
 216                             self.store_operand(&bcx, llscratch, None, op);
 217                             llscratch
 218                         }
 219                         Ref(llval, align) => {
 220                             assert_eq!(align, Alignment::AbiAligned,
 221                                        "return pointer is unaligned!");
 222                             llval
 223                         }
 224                     };
 225                     let load = bcx.load(
 226                         bcx.pointercast(llslot, cast_ty.ptr_to()),
 227                         Some(llalign_of_min(bcx.ccx, ret.ty)));
 228                     load
 229                 } else {
 230                     let op = self.trans_consume(&bcx, &mir::Lvalue::Local(mir::RETURN_POINTER));
 231                     if let Ref(llval, align) = op.val {
 232                         base::load_ty(&bcx, llval, align, op.ty)
 233                     } else {
 234                         op.pack_if_pair(&bcx).immediate()
 235                     }
 236                 };
 237                 bcx.ret(llval);
 238             }
 239
 240             mir::TerminatorKind::Unreachable => {
 241                 bcx.unreachable();
 242             }
 243
 244             mir::TerminatorKind::Drop { ref location, target, unwind } => {
 245                 let ty = location.ty(&self.mir, bcx.tcx()).to_ty(bcx.tcx());
 246                 let ty = self.monomorphize(&ty);
 247
 248                 // Double check for necessity to drop
 249                 if !bcx.ccx.shared().type_needs_drop(ty) {
 250                     funclet_br(self, bcx, target);
 251                     return;
 252                 }
 253
 254                 let mut lvalue = self.trans_lvalue(&bcx, location);
 255                 let drop_fn = glue::get_drop_glue(bcx.ccx, ty);
 256                 let drop_ty = glue::get_drop_glue_type(bcx.ccx.shared(), ty);
 257                 if bcx.ccx.shared().type_is_sized(ty) && drop_ty != ty {
 258                     lvalue.llval = bcx.pointercast(
 259                         lvalue.llval, type_of::type_of(bcx.ccx, drop_ty).ptr_to());
 260                 }
 261                 let args = &[lvalue.llval, lvalue.llextra][..1 + lvalue.has_extra() as usize];
 262                 if let Some(unwind) = unwind {
 263                     bcx.invoke(
 264                         drop_fn,
 265                         args,
 266                         self.blocks[target],
 267                         llblock(self, unwind),
 268                         cleanup_bundle
 269                     );
 270                 } else {
 271                     bcx.call(drop_fn, args, cleanup_bundle);
 272                     funclet_br(self, bcx, target);
 273                 }
 274             }
 275
 276             mir::TerminatorKind::Assert { ref cond, expected, ref msg, target, cleanup } => {
 277                 let cond = self.trans_operand(&bcx, cond).immediate();
 278                 let mut const_cond = common::const_to_opt_u128(cond, false).map(|c| c == 1);
 279
 280                 // This case can currently arise only from functions marked
 281                 // with #[rustc_inherit_overflow_checks] and inlined from
 282                 // another crate (mostly core::num generic/#[inline] fns),
 283                 // while the current crate doesn't use overflow checks.
 284                 // NOTE: Unlike binops, negation doesn't have its own
 285                 // checked operation, just a comparison with the minimum
 286                 // value, so we have to check for the assert message.
 287                 if !bcx.ccx.check_overflow() {
 288                     use rustc_const_math::ConstMathErr::Overflow;
 289                     use rustc_const_math::Op::Neg;
 290
 291                     if let mir::AssertMessage::Math(Overflow(Neg)) = *msg {
 292                         const_cond = Some(expected);
 293                     }
 294                 }
 295
 296                 // Don't translate the panic block if success if known.
 297                 if const_cond == Some(expected) {
 298                     funclet_br(self, bcx, target);
 299                     return;
 300                 }
 301
 302                 // Pass the condition through llvm.expect for branch hinting.
 303                 let expect = bcx.ccx.get_intrinsic(&"llvm.expect.i1");
 304                 let cond = bcx.call(expect, &[cond, C_bool(bcx.ccx, expected)], None);
 305
 306                 // Create the failure block and the conditional branch to it.
 307                 let lltarget = llblock(self, target);
 308                 let panic_block = self.new_block("panic");
 309                 if expected {
 310                     bcx.cond_br(cond, lltarget, panic_block.llbb());
 311                 } else {
 312                     bcx.cond_br(cond, panic_block.llbb(), lltarget);
 313                 }
 314
 315                 // After this point, bcx is the block for the call to panic.
 316                 bcx = panic_block;
 317                 self.set_debug_loc(&bcx, terminator.source_info);
 318
 319                 // Get the location information.
 320                 let loc = bcx.sess().codemap().lookup_char_pos(span.lo);
 321                 let filename = Symbol::intern(&loc.file.name).as_str();
 322                 let filename = C_str_slice(bcx.ccx, filename);
 323                 let line = C_u32(bcx.ccx, loc.line as u32);
 324
 325                 // Put together the arguments to the panic entry point.
 326                 let (lang_item, args, const_err) = match *msg {
 327                     mir::AssertMessage::BoundsCheck { ref len, ref index } => {
 328                         let len = self.trans_operand(&mut bcx, len).immediate();
 329                         let index = self.trans_operand(&mut bcx, index).immediate();
 330
 331                         let const_err = common::const_to_opt_u128(len, false)
 332                             .and_then(|len| common::const_to_opt_u128(index, false)
 333                                 .map(|index| ErrKind::IndexOutOfBounds {
 334                                     len: len as u64,
 335                                     index: index as u64
 336                                 }));
 337
 338                         let file_line = C_struct(bcx.ccx, &[filename, line], false);
 339                         let align = llalign_of_min(bcx.ccx, common::val_ty(file_line));
 340                         let file_line = consts::addr_of(bcx.ccx,
 341                                                         file_line,
 342                                                         align,
 343                                                         "panic_bounds_check_loc");
 344                         (lang_items::PanicBoundsCheckFnLangItem,
 345                          vec![file_line, index, len],
 346                          const_err)
 347                     }
 348                     mir::AssertMessage::Math(ref err) => {
 349                         let msg_str = Symbol::intern(err.description()).as_str();
 350                         let msg_str = C_str_slice(bcx.ccx, msg_str);
 351                         let msg_file_line = C_struct(bcx.ccx,
 352                                                      &[msg_str, filename, line],
 353                                                      false);
 354                         let align = llalign_of_min(bcx.ccx, common::val_ty(msg_file_line));
 355                         let msg_file_line = consts::addr_of(bcx.ccx,
 356                                                             msg_file_line,
 357                                                             align,
 358                                                             "panic_loc");
 359                         (lang_items::PanicFnLangItem,
 360                          vec![msg_file_line],
 361                          Some(ErrKind::Math(err.clone())))
 362                     }
 363                 };
 364
 365                 // If we know we always panic, and the error message
 366                 // is also constant, then we can produce a warning.
 367                 if const_cond == Some(!expected) {
 368                     if let Some(err) = const_err {
 369                         let err = ConstEvalErr{ span: span, kind: err };
 370                         let mut diag = bcx.tcx().sess.struct_span_warn(
 371                             span, "this expression will panic at run-time");
 372                         note_const_eval_err(bcx.tcx(), &err, span, "expression", &mut diag);
 373                         diag.emit();
 374                     }
 375                 }
 376
 377                 // Obtain the panic entry point.
 378                 let def_id = common::langcall(bcx.tcx(), Some(span), "", lang_item);
 379                 let callee = Callee::def(bcx.ccx, def_id,
 380                     bcx.ccx.empty_substs_for_def_id(def_id));
 381                 let llfn = callee.reify(bcx.ccx);
 382
 383                 // Translate the actual panic invoke/call.
 384                 if let Some(unwind) = cleanup {
 385                     bcx.invoke(llfn,
 386                                &args,
 387                                self.unreachable_block(),
 388                                llblock(self, unwind),
 389                                cleanup_bundle);
 390                 } else {
 391                     bcx.call(llfn, &args, cleanup_bundle);
 392                     bcx.unreachable();
 393                 }
 394             }
 395
 396             mir::TerminatorKind::DropAndReplace { .. } => {
 397                 bug!("undesugared DropAndReplace in trans: {:?}", data);
 398             }
 399
 400             mir::TerminatorKind::Call { ref func, ref args, ref destination, ref cleanup } => {
 401                 // Create the callee. This is a fn ptr or zero-sized and hence a kind of scalar.
 402                 let callee = self.trans_operand(&bcx, func);
 403
 404                 let (mut callee, abi, sig) = match callee.ty.sty {
 405                     ty::TyFnDef(def_id, substs, f) => {
 406                         (Callee::def(bcx.ccx, def_id, substs), f.abi, &f.sig)
 407                     }
 408                     ty::TyFnPtr(f) => {
 409                         (Callee {
 410                             data: Fn(callee.immediate()),
 411                             ty: callee.ty
 412                         }, f.abi, &f.sig)
 413                     }
 414                     _ => bug!("{} is not callable", callee.ty)
 415                 };
 416
 417                 let sig = bcx.tcx().erase_late_bound_regions_and_normalize(sig);
 418
 419                 // Handle intrinsics old trans wants Expr's for, ourselves.
 420                 let intrinsic = match (&callee.ty.sty, &callee.data) {
 421                     (&ty::TyFnDef(def_id, ..), &Intrinsic) => {
 422                         Some(bcx.tcx().item_name(def_id).as_str())
 423                     }
 424                     _ => None
 425                 };
 426                 let mut intrinsic = intrinsic.as_ref().map(|s| &s[..]);
 427
 428                 if intrinsic == Some("move_val_init") {
 429                     let &(_, target) = destination.as_ref().unwrap();
 430                     // The first argument is a thin destination pointer.
 431                     let llptr = self.trans_operand(&bcx, &args[0]).immediate();
 432                     let val = self.trans_operand(&bcx, &args[1]);
 433                     self.store_operand(&bcx, llptr, None, val);
 434                     funclet_br(self, bcx, target);
 435                     return;
 436                 }
 437
 438                 if intrinsic == Some("transmute") {
 439                     let &(ref dest, target) = destination.as_ref().unwrap();
 440                     self.trans_transmute(&bcx, &args[0], dest);
 441                     funclet_br(self, bcx, target);
 442                     return;
 443                 }
 444
 445                 let extra_args = &args[sig.inputs().len()..];
 446                 let extra_args = extra_args.iter().map(|op_arg| {
 447                     let op_ty = op_arg.ty(&self.mir, bcx.tcx());
 448                     self.monomorphize(&op_ty)
 449                 }).collect::<Vec<_>>();
 450                 let fn_ty = callee.direct_fn_type(bcx.ccx, &extra_args);
 451
 452                 if intrinsic == Some("drop_in_place") {
 453                     let &(_, target) = destination.as_ref().unwrap();
 454                     let ty = if let ty::TyFnDef(_, substs, _) = callee.ty.sty {
 455                         substs.type_at(0)
 456                     } else {
 457                         bug!("Unexpected ty: {}", callee.ty);
 458                     };
 459
 460                     // Double check for necessity to drop
 461                     if !bcx.ccx.shared().type_needs_drop(ty) {
 462                         funclet_br(self, bcx, target);
 463                         return;
 464                     }
 465
 466                     let drop_fn = glue::get_drop_glue(bcx.ccx, ty);
 467                     let llty = fn_ty.llvm_type(bcx.ccx).ptr_to();
 468                     callee.data = Fn(bcx.pointercast(drop_fn, llty));
 469                     intrinsic = None;
 470                 }
 471
 472                 // The arguments we'll be passing. Plus one to account for outptr, if used.
 473                 let arg_count = fn_ty.args.len() + fn_ty.ret.is_indirect() as usize;
 474                 let mut llargs = Vec::with_capacity(arg_count);
 475
 476                 // Prepare the return value destination
 477                 let ret_dest = if let Some((ref dest, _)) = *destination {
 478                     let is_intrinsic = if let Intrinsic = callee.data {
 479                         true
 480                     } else {
 481                         false
 482                     };
 483                     self.make_return_dest(&bcx, dest, &fn_ty.ret, &mut llargs, is_intrinsic)
 484                 } else {
 485                     ReturnDest::Nothing
 486                 };
 487
 488                 // Split the rust-call tupled arguments off.
 489                 let (first_args, untuple) = if abi == Abi::RustCall && !args.is_empty() {
 490                     let (tup, args) = args.split_last().unwrap();
 491                     (args, Some(tup))
 492                 } else {
 493                     (&args[..], None)
 494                 };
 495
 496                 let is_shuffle = intrinsic.map_or(false, |name| {
 497                     name.starts_with("simd_shuffle")
 498                 });
 499                 let mut idx = 0;
 500                 for arg in first_args {
 501                     // The indices passed to simd_shuffle* in the
 502                     // third argument must be constant. This is
 503                     // checked by const-qualification, which also
 504                     // promotes any complex rvalues to constants.
 505                     if is_shuffle && idx == 2 {
 506                         match *arg {
 507                             mir::Operand::Consume(_) => {
 508                                 span_bug!(span, "shuffle indices must be constant");
 509                             }
 510                             mir::Operand::Constant(ref constant) => {
 511                                 let val = self.trans_constant(&bcx, constant);
 512                                 llargs.push(val.llval);
 513                                 idx += 1;
 514                                 continue;
 515                             }
 516                         }
 517                     }
 518
 519                     let op = self.trans_operand(&bcx, arg);
 520                     self.trans_argument(&bcx, op, &mut llargs, &fn_ty,
 521                                         &mut idx, &mut callee.data);
 522                 }
 523                 if let Some(tup) = untuple {
 524                     self.trans_arguments_untupled(&bcx, tup, &mut llargs, &fn_ty,
 525                                                   &mut idx, &mut callee.data)
 526                 }
 527
 528                 let fn_ptr = match callee.data {
 529                     NamedTupleConstructor(_) => {
 530                         // FIXME translate this like mir::Rvalue::Aggregate.
 531                         callee.reify(bcx.ccx)
 532                     }
 533                     Intrinsic => {
 534                         use intrinsic::trans_intrinsic_call;
 535
 536                         let (dest, llargs) = match ret_dest {
 537                             _ if fn_ty.ret.is_indirect() => {
 538                                 (llargs[0], &llargs[1..])
 539                             }
 540                             ReturnDest::Nothing => {
 541                                 (C_undef(fn_ty.ret.original_ty.ptr_to()), &llargs[..])
 542                             }
 543                             ReturnDest::IndirectOperand(dst, _) |
 544                             ReturnDest::Store(dst) => (dst, &llargs[..]),
 545                             ReturnDest::DirectOperand(_) =>
 546                                 bug!("Cannot use direct operand with an intrinsic call")
 547                         };
 548
 549                         trans_intrinsic_call(&bcx, callee.ty, &fn_ty, &llargs, dest,
 550                             terminator.source_info.span);
 551
 552                         if let ReturnDest::IndirectOperand(dst, _) = ret_dest {
 553                             // Make a fake operand for store_return
 554                             let op = OperandRef {
 555                                 val: Ref(dst, Alignment::AbiAligned),
 556                                 ty: sig.output(),
 557                             };
 558                             self.store_return(&bcx, ret_dest, fn_ty.ret, op);
 559                         }
 560
 561                         if let Some((_, target)) = *destination {
 562                             funclet_br(self, bcx, target);
 563                         } else {
 564                             bcx.unreachable();
 565                         }
 566
 567                         return;
 568                     }
 569                     Fn(f) => f,
 570                     Virtual(_) => bug!("Virtual fn ptr not extracted")
 571                 };
 572
 573                 // Many different ways to call a function handled here
 574                 if let &Some(cleanup) = cleanup {
 575                     let ret_bcx = if let Some((_, target)) = *destination {
 576                         self.blocks[target]
 577                     } else {
 578                         self.unreachable_block()
 579                     };
 580                     let invokeret = bcx.invoke(fn_ptr,
 581                                                &llargs,
 582                                                ret_bcx,
 583                                                llblock(self, cleanup),
 584                                                cleanup_bundle);
 585                     fn_ty.apply_attrs_callsite(invokeret);
 586
 587                     if let Some((_, target)) = *destination {
 588                         let ret_bcx = self.get_builder(target);
 589                         self.set_debug_loc(&ret_bcx, terminator.source_info);
 590                         let op = OperandRef {
 591                             val: Immediate(invokeret),
 592                             ty: sig.output(),
 593                         };
 594                         self.store_return(&ret_bcx, ret_dest, fn_ty.ret, op);
 595                     }
 596                 } else {
 597                     let llret = bcx.call(fn_ptr, &llargs, cleanup_bundle);
 598                     fn_ty.apply_attrs_callsite(llret);
 599                     if let Some((_, target)) = *destination {
 600                         let op = OperandRef {
 601                             val: Immediate(llret),
 602                             ty: sig.output(),
 603                         };
 604                         self.store_return(&bcx, ret_dest, fn_ty.ret, op);
 605                         funclet_br(self, bcx, target);
 606                     } else {
 607                         bcx.unreachable();
 608                     }
 609                 }
 610             }
 611         }
 612     }
 613
 614     fn trans_argument(&mut self,
 615                       bcx: &Builder<'a, 'tcx>,
 616                       op: OperandRef<'tcx>,
 617                       llargs: &mut Vec<ValueRef>,
 618                       fn_ty: &FnType,
 619                       next_idx: &mut usize,
 620                       callee: &mut CalleeData) {
 621         if let Pair(a, b) = op.val {
 622             // Treat the values in a fat pointer separately.
 623             if common::type_is_fat_ptr(bcx.ccx, op.ty) {
 624                 let (ptr, meta) = (a, b);
 625                 if *next_idx == 0 {
 626                     if let Virtual(idx) = *callee {
 627                         let llfn = meth::get_virtual_method(bcx, meta, idx);
 628                         let llty = fn_ty.llvm_type(bcx.ccx).ptr_to();
 629                         *callee = Fn(bcx.pointercast(llfn, llty));
 630                     }
 631                 }
 632
 633                 let imm_op = |x| OperandRef {
 634                     val: Immediate(x),
 635                     // We won't be checking the type again.
 636                     ty: bcx.tcx().types.err
 637                 };
 638                 self.trans_argument(bcx, imm_op(ptr), llargs, fn_ty, next_idx, callee);
 639                 self.trans_argument(bcx, imm_op(meta), llargs, fn_ty, next_idx, callee);
 640                 return;
 641             }
 642         }
 643
 644         let arg = &fn_ty.args[*next_idx];
 645         *next_idx += 1;
 646
 647         // Fill padding with undef value, where applicable.
 648         if let Some(ty) = arg.pad {
 649             llargs.push(C_undef(ty));
 650         }
 651
 652         if arg.is_ignore() {
 653             return;
 654         }
 655
 656         // Force by-ref if we have to load through a cast pointer.
 657         let (mut llval, align, by_ref) = match op.val {
 658             Immediate(_) | Pair(..) => {
 659                 if arg.is_indirect() || arg.cast.is_some() {
 660                     let llscratch = bcx.alloca(arg.original_ty, "arg");
 661                     self.store_operand(bcx, llscratch, None, op);
 662                     (llscratch, Alignment::AbiAligned, true)
 663                 } else {
 664                     (op.pack_if_pair(bcx).immediate(), Alignment::AbiAligned, false)
 665                 }
 666             }
 667             Ref(llval, Alignment::Packed) if arg.is_indirect() => {
 668                 // `foo(packed.large_field)`. We can't pass the (unaligned) field directly. I
 669                 // think that ATM (Rust 1.16) we only pass temporaries, but we shouldn't
 670                 // have scary latent bugs around.
 671
 672                 let llscratch = bcx.alloca(arg.original_ty, "arg");
 673                 base::memcpy_ty(bcx, llscratch, llval, op.ty, Some(1));
 674                 (llscratch, Alignment::AbiAligned, true)
 675             }
 676             Ref(llval, align) => (llval, align, true)
 677         };
 678
 679         if by_ref && !arg.is_indirect() {
 680             // Have to load the argument, maybe while casting it.
 681             if arg.original_ty == Type::i1(bcx.ccx) {
 682                 // We store bools as i8 so we need to truncate to i1.
 683                 llval = bcx.load_range_assert(llval, 0, 2, llvm::False, None);
 684                 llval = bcx.trunc(llval, arg.original_ty);
 685             } else if let Some(ty) = arg.cast {
 686                 llval = bcx.load(bcx.pointercast(llval, ty.ptr_to()),
 687                                  align.min_with(llalign_of_min(bcx.ccx, arg.ty)));
 688             } else {
 689                 llval = bcx.load(llval, align.to_align());
 690             }
 691         }
 692
 693         llargs.push(llval);
 694     }
 695
 696     fn trans_arguments_untupled(&mut self,
 697                                 bcx: &Builder<'a, 'tcx>,
 698                                 operand: &mir::Operand<'tcx>,
 699                                 llargs: &mut Vec<ValueRef>,
 700                                 fn_ty: &FnType,
 701                                 next_idx: &mut usize,
 702                                 callee: &mut CalleeData) {
 703         let tuple = self.trans_operand(bcx, operand);
 704
 705         let arg_types = match tuple.ty.sty {
 706             ty::TyTuple(ref tys, _) => tys,
 707             _ => span_bug!(self.mir.span,
 708                            "bad final argument to \"rust-call\" fn {:?}", tuple.ty)
 709         };
 710
 711         // Handle both by-ref and immediate tuples.
 712         match tuple.val {
 713             Ref(llval, align) => {
 714                 for (n, &ty) in arg_types.iter().enumerate() {
 715                     let ptr = LvalueRef::new_sized_ty(llval, tuple.ty, align);
 716                     let (ptr, align) = ptr.trans_field_ptr(bcx, n);
 717                     let val = if common::type_is_fat_ptr(bcx.ccx, ty) {
 718                         let (lldata, llextra) = base::load_fat_ptr(bcx, ptr, align, ty);
 719                         Pair(lldata, llextra)
 720                     } else {
 721                         // trans_argument will load this if it needs to
 722                         Ref(ptr, align)
 723                     };
 724                     let op = OperandRef {
 725                         val: val,
 726                         ty: ty
 727                     };
 728                     self.trans_argument(bcx, op, llargs, fn_ty, next_idx, callee);
 729                 }
 730
 731             }
 732             Immediate(llval) => {
 733                 let l = bcx.ccx.layout_of(tuple.ty);
 734                 let v = if let layout::Univariant { ref variant, .. } = *l {
 735                     variant
 736                 } else {
 737                     bug!("Not a tuple.");
 738                 };
 739                 for (n, &ty) in arg_types.iter().enumerate() {
 740                     let mut elem = bcx.extract_value(llval, v.memory_index[n] as usize);
 741                     // Truncate bools to i1, if needed
 742                     if ty.is_bool() && common::val_ty(elem) != Type::i1(bcx.ccx) {
 743                         elem = bcx.trunc(elem, Type::i1(bcx.ccx));
 744                     }
 745                     // If the tuple is immediate, the elements are as well
 746                     let op = OperandRef {
 747                         val: Immediate(elem),
 748                         ty: ty
 749                     };
 750                     self.trans_argument(bcx, op, llargs, fn_ty, next_idx, callee);
 751                 }
 752             }
 753             Pair(a, b) => {
 754                 let elems = [a, b];
 755                 for (n, &ty) in arg_types.iter().enumerate() {
 756                     let mut elem = elems[n];
 757                     // Truncate bools to i1, if needed
 758                     if ty.is_bool() && common::val_ty(elem) != Type::i1(bcx.ccx) {
 759                         elem = bcx.trunc(elem, Type::i1(bcx.ccx));
 760                     }
 761                     // Pair is always made up of immediates
 762                     let op = OperandRef {
 763                         val: Immediate(elem),
 764                         ty: ty
 765                     };
 766                     self.trans_argument(bcx, op, llargs, fn_ty, next_idx, callee);
 767                 }
 768             }
 769         }
 770
 771     }
 772
 773     fn get_personality_slot(&mut self, bcx: &Builder<'a, 'tcx>) -> ValueRef {
 774         let ccx = bcx.ccx;
 775         if let Some(slot) = self.llpersonalityslot {
 776             slot
 777         } else {
 778             let llretty = Type::struct_(ccx, &[Type::i8p(ccx), Type::i32(ccx)], false);
 779             let slot = bcx.alloca(llretty, "personalityslot");
 780             self.llpersonalityslot = Some(slot);
 781             Lifetime::Start.call(bcx, slot);
 782             slot
 783         }
 784     }
 785
 786     /// Return the landingpad wrapper around the given basic block
 787     ///
 788     /// No-op in MSVC SEH scheme.
 789     fn landing_pad_to(&mut self, target_bb: mir::BasicBlock) -> BasicBlockRef {
 790         if let Some(block) = self.landing_pads[target_bb] {
 791             return block;
 792         }
 793
 794         if base::wants_msvc_seh(self.ccx.sess()) {
 795             return self.blocks[target_bb];
 796         }
 797
 798         let target = self.get_builder(target_bb);
 799
 800         let bcx = self.new_block("cleanup");
 801         self.landing_pads[target_bb] = Some(bcx.llbb());
 802
 803         let ccx = bcx.ccx;
 804         let llpersonality = self.ccx.eh_personality();
 805         let llretty = Type::struct_(ccx, &[Type::i8p(ccx), Type::i32(ccx)], false);
 806         let llretval = bcx.landing_pad(llretty, llpersonality, 1, self.llfn);
 807         bcx.set_cleanup(llretval);
 808         let slot = self.get_personality_slot(&bcx);
 809         bcx.store(llretval, slot, None);
 810         bcx.br(target.llbb());
 811         bcx.llbb()
 812     }
 813
 814     fn unreachable_block(&mut self) -> BasicBlockRef {
 815         self.unreachable_block.unwrap_or_else(|| {
 816             let bl = self.new_block("unreachable");
 817             bl.unreachable();
 818             self.unreachable_block = Some(bl.llbb());
 819             bl.llbb()
 820         })
 821     }
 822
 823     pub fn new_block(&self, name: &str) -> Builder<'a, 'tcx> {
 824         Builder::new_block(self.ccx, self.llfn, name)
 825     }
 826
 827     pub fn get_builder(&self, bb: mir::BasicBlock) -> Builder<'a, 'tcx> {
 828         let builder = Builder::with_ccx(self.ccx);
 829         builder.position_at_end(self.blocks[bb]);
 830         builder
 831     }
 832
 833     fn make_return_dest(&mut self, bcx: &Builder<'a, 'tcx>,
 834                         dest: &mir::Lvalue<'tcx>, fn_ret_ty: &ArgType,
 835                         llargs: &mut Vec<ValueRef>, is_intrinsic: bool) -> ReturnDest {
 836         // If the return is ignored, we can just return a do-nothing ReturnDest
 837         if fn_ret_ty.is_ignore() {
 838             return ReturnDest::Nothing;
 839         }
 840         let dest = if let mir::Lvalue::Local(index) = *dest {
 841             let ret_ty = self.monomorphized_lvalue_ty(dest);
 842             match self.locals[index] {
 843                 LocalRef::Lvalue(dest) => dest,
 844                 LocalRef::Operand(None) => {
 845                     // Handle temporary lvalues, specifically Operand ones, as
 846                     // they don't have allocas
 847                     return if fn_ret_ty.is_indirect() {
 848                         // Odd, but possible, case, we have an operand temporary,
 849                         // but the calling convention has an indirect return.
 850                         let tmp = LvalueRef::alloca(bcx, ret_ty, "tmp_ret");
 851                         llargs.push(tmp.llval);
 852                         ReturnDest::IndirectOperand(tmp.llval, index)
 853                     } else if is_intrinsic {
 854                         // Currently, intrinsics always need a location to store
 855                         // the result. so we create a temporary alloca for the
 856                         // result
 857                         let tmp = LvalueRef::alloca(bcx, ret_ty, "tmp_ret");
 858                         ReturnDest::IndirectOperand(tmp.llval, index)
 859                     } else {
 860                         ReturnDest::DirectOperand(index)
 861                     };
 862                 }
 863                 LocalRef::Operand(Some(_)) => {
 864                     bug!("lvalue local already assigned to");
 865                 }
 866             }
 867         } else {
 868             self.trans_lvalue(bcx, dest)
 869         };
 870         if fn_ret_ty.is_indirect() {
 871             llargs.push(dest.llval);
 872             ReturnDest::Nothing
 873         } else {
 874             ReturnDest::Store(dest.llval)
 875         }
 876     }
 877
 878     fn trans_transmute(&mut self, bcx: &Builder<'a, 'tcx>,
 879                        src: &mir::Operand<'tcx>,
 880                        dst: &mir::Lvalue<'tcx>) {
 881         if let mir::Lvalue::Local(index) = *dst {
 882             match self.locals[index] {
 883                 LocalRef::Lvalue(lvalue) => self.trans_transmute_into(bcx, src, &lvalue),
 884                 LocalRef::Operand(None) => {
 885                     let lvalue_ty = self.monomorphized_lvalue_ty(dst);
 886                     assert!(!lvalue_ty.has_erasable_regions());
 887                     let lvalue = LvalueRef::alloca(bcx, lvalue_ty, "transmute_temp");
 888                     self.trans_transmute_into(bcx, src, &lvalue);
 889                     let op = self.trans_load(bcx, lvalue.llval, lvalue.alignment, lvalue_ty);
 890                     self.locals[index] = LocalRef::Operand(Some(op));
 891                 }
 892                 LocalRef::Operand(Some(_)) => {
 893                     let ty = self.monomorphized_lvalue_ty(dst);
 894                     assert!(common::type_is_zero_size(bcx.ccx, ty),
 895                             "assigning to initialized SSAtemp");
 896                 }
 897             }
 898         } else {
 899             let dst = self.trans_lvalue(bcx, dst);
 900             self.trans_transmute_into(bcx, src, &dst);
 901         }
 902     }
 903
 904     fn trans_transmute_into(&mut self, bcx: &Builder<'a, 'tcx>,
 905                             src: &mir::Operand<'tcx>,
 906                             dst: &LvalueRef<'tcx>) {
 907         let mut val = self.trans_operand(bcx, src);
 908         if let ty::TyFnDef(def_id, substs, _) = val.ty.sty {
 909             let llouttype = type_of::type_of(bcx.ccx, dst.ty.to_ty(bcx.tcx()));
 910             let out_type_size = llbitsize_of_real(bcx.ccx, llouttype);
 911             if out_type_size != 0 {
 912                 // FIXME #19925 Remove this hack after a release cycle.
 913                 let f = Callee::def(bcx.ccx, def_id, substs);
 914                 let ty = match f.ty.sty {
 915                     ty::TyFnDef(.., f) => bcx.tcx().mk_fn_ptr(f),
 916                     _ => f.ty
 917                 };
 918                 val = OperandRef {
 919                     val: Immediate(f.reify(bcx.ccx)),
 920                     ty: ty
 921                 };
 922             }
 923         }
 924
 925         let llty = type_of::type_of(bcx.ccx, val.ty);
 926         let cast_ptr = bcx.pointercast(dst.llval, llty.ptr_to());
 927         let in_type = val.ty;
 928         let out_type = dst.ty.to_ty(bcx.tcx());;
 929         let llalign = cmp::min(align_of(bcx.ccx, in_type), align_of(bcx.ccx, out_type));
 930         self.store_operand(bcx, cast_ptr, Some(llalign), val);
 931     }
 932
 933
 934     // Stores the return value of a function call into it's final location.
 935     fn store_return(&mut self,
 936                     bcx: &Builder<'a, 'tcx>,
 937                     dest: ReturnDest,
 938                     ret_ty: ArgType,
 939                     op: OperandRef<'tcx>) {
 940         use self::ReturnDest::*;
 941
 942         match dest {
 943             Nothing => (),
 944             Store(dst) => ret_ty.store(bcx, op.immediate(), dst),
 945             IndirectOperand(tmp, index) => {
 946                 let op = self.trans_load(bcx, tmp, Alignment::AbiAligned, op.ty);
 947                 self.locals[index] = LocalRef::Operand(Some(op));
 948             }
 949             DirectOperand(index) => {
 950                 // If there is a cast, we have to store and reload.
 951                 let op = if ret_ty.cast.is_some() {
 952                     let tmp = LvalueRef::alloca(bcx, op.ty, "tmp_ret");
 953                     ret_ty.store(bcx, op.immediate(), tmp.llval);
 954                     self.trans_load(bcx, tmp.llval, tmp.alignment, op.ty)
 955                 } else {
 956                     op.unpack_if_pair(bcx)
 957                 };
 958                 self.locals[index] = LocalRef::Operand(Some(op));
 959             }
 960         }
 961     }
 962 }
 963
 964 enum ReturnDest {
 965     // Do nothing, the return value is indirect or ignored
 966     Nothing,
 967     // Store the return value to the pointer
 968     Store(ValueRef),
 969     // Stores an indirect return value to an operand local lvalue
 970     IndirectOperand(ValueRef, mir::Local),
 971     // Stores a direct return value to an operand local lvalue
 972     DirectOperand(mir::Local)
 973 }