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, ConstEvalErr, note_const_eval_err};
  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).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");
 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 err = ConstEvalErr{ span: span, kind: err };
 358                         let mut diag = bcx.tcx().sess.struct_span_warn(
 359                             span, "this expression will panic at run-time");
 360                         note_const_eval_err(bcx.tcx(), &err, span, "expression", &mut diag);
 361                         diag.emit();
 362                     }
 363                 }
 364
 365                 // Obtain the panic entry point.
 366                 let def_id = common::langcall(bcx.tcx(), Some(span), "", lang_item);
 367                 let callee = Callee::def(bcx.ccx(), def_id,
 368                     bcx.ccx().empty_substs_for_def_id(def_id));
 369                 let llfn = callee.reify(bcx.ccx());
 370
 371                 // Translate the actual panic invoke/call.
 372                 if let Some(unwind) = cleanup {
 373                     bcx.invoke(llfn,
 374                                &args,
 375                                self.unreachable_block().llbb,
 376                                llblock(self, unwind),
 377                                cleanup_bundle);
 378                 } else {
 379                     bcx.call(llfn, &args, cleanup_bundle);
 380                     bcx.unreachable();
 381                 }
 382             }
 383
 384             mir::TerminatorKind::DropAndReplace { .. } => {
 385                 bug!("undesugared DropAndReplace in trans: {:?}", data);
 386             }
 387
 388             mir::TerminatorKind::Call { ref func, ref args, ref destination, ref cleanup } => {
 389                 // Create the callee. This is a fn ptr or zero-sized and hence a kind of scalar.
 390                 let callee = self.trans_operand(&bcx, func);
 391
 392                 let (mut callee, abi, sig) = match callee.ty.sty {
 393                     ty::TyFnDef(def_id, substs, f) => {
 394                         (Callee::def(bcx.ccx(), def_id, substs), f.abi, &f.sig)
 395                     }
 396                     ty::TyFnPtr(f) => {
 397                         (Callee {
 398                             data: Fn(callee.immediate()),
 399                             ty: callee.ty
 400                         }, f.abi, &f.sig)
 401                     }
 402                     _ => bug!("{} is not callable", callee.ty)
 403                 };
 404
 405                 let sig = bcx.tcx().erase_late_bound_regions(sig);
 406
 407                 // Handle intrinsics old trans wants Expr's for, ourselves.
 408                 let intrinsic = match (&callee.ty.sty, &callee.data) {
 409                     (&ty::TyFnDef(def_id, _, _), &Intrinsic) => {
 410                         Some(bcx.tcx().item_name(def_id).as_str())
 411                     }
 412                     _ => None
 413                 };
 414                 let intrinsic = intrinsic.as_ref().map(|s| &s[..]);
 415
 416                 if intrinsic == Some("move_val_init") {
 417                     let &(_, target) = destination.as_ref().unwrap();
 418                     // The first argument is a thin destination pointer.
 419                     let llptr = self.trans_operand(&bcx, &args[0]).immediate();
 420                     let val = self.trans_operand(&bcx, &args[1]);
 421                     self.store_operand(&bcx, llptr, val);
 422                     funclet_br(self, bcx, target);
 423                     return;
 424                 }
 425
 426                 if intrinsic == Some("transmute") {
 427                     let &(ref dest, target) = destination.as_ref().unwrap();
 428                     self.with_lvalue_ref(&bcx, dest, |this, dest| {
 429                         this.trans_transmute(&bcx, &args[0], dest);
 430                     });
 431
 432                     funclet_br(self, bcx, target);
 433                     return;
 434                 }
 435
 436                 let extra_args = &args[sig.inputs.len()..];
 437                 let extra_args = extra_args.iter().map(|op_arg| {
 438                     let op_ty = op_arg.ty(&self.mir, bcx.tcx());
 439                     bcx.monomorphize(&op_ty)
 440                 }).collect::<Vec<_>>();
 441                 let fn_ty = callee.direct_fn_type(bcx.ccx(), &extra_args);
 442
 443                 // The arguments we'll be passing. Plus one to account for outptr, if used.
 444                 let arg_count = fn_ty.args.len() + fn_ty.ret.is_indirect() as usize;
 445                 let mut llargs = Vec::with_capacity(arg_count);
 446
 447                 // Prepare the return value destination
 448                 let ret_dest = if let Some((ref dest, _)) = *destination {
 449                     let is_intrinsic = if let Intrinsic = callee.data {
 450                         true
 451                     } else {
 452                         false
 453                     };
 454                     self.make_return_dest(&bcx, dest, &fn_ty.ret, &mut llargs, is_intrinsic)
 455                 } else {
 456                     ReturnDest::Nothing
 457                 };
 458
 459                 // Split the rust-call tupled arguments off.
 460                 let (first_args, untuple) = if abi == Abi::RustCall && !args.is_empty() {
 461                     let (tup, args) = args.split_last().unwrap();
 462                     (args, Some(tup))
 463                 } else {
 464                     (&args[..], None)
 465                 };
 466
 467                 let is_shuffle = intrinsic.map_or(false, |name| {
 468                     name.starts_with("simd_shuffle")
 469                 });
 470                 let mut idx = 0;
 471                 for arg in first_args {
 472                     // The indices passed to simd_shuffle* in the
 473                     // third argument must be constant. This is
 474                     // checked by const-qualification, which also
 475                     // promotes any complex rvalues to constants.
 476                     if is_shuffle && idx == 2 {
 477                         match *arg {
 478                             mir::Operand::Consume(_) => {
 479                                 span_bug!(span, "shuffle indices must be constant");
 480                             }
 481                             mir::Operand::Constant(ref constant) => {
 482                                 let val = self.trans_constant(&bcx, constant);
 483                                 llargs.push(val.llval);
 484                                 idx += 1;
 485                                 continue;
 486                             }
 487                         }
 488                     }
 489
 490                     let op = self.trans_operand(&bcx, arg);
 491                     self.trans_argument(&bcx, op, &mut llargs, &fn_ty,
 492                                         &mut idx, &mut callee.data);
 493                 }
 494                 if let Some(tup) = untuple {
 495                     self.trans_arguments_untupled(&bcx, tup, &mut llargs, &fn_ty,
 496                                                   &mut idx, &mut callee.data)
 497                 }
 498
 499                 let fn_ptr = match callee.data {
 500                     NamedTupleConstructor(_) => {
 501                         // FIXME translate this like mir::Rvalue::Aggregate.
 502                         callee.reify(bcx.ccx())
 503                     }
 504                     Intrinsic => {
 505                         use intrinsic::trans_intrinsic_call;
 506
 507                         let (dest, llargs) = match ret_dest {
 508                             _ if fn_ty.ret.is_indirect() => {
 509                                 (llargs[0], &llargs[1..])
 510                             }
 511                             ReturnDest::Nothing => {
 512                                 (C_undef(fn_ty.ret.original_ty.ptr_to()), &llargs[..])
 513                             }
 514                             ReturnDest::IndirectOperand(dst, _) |
 515                             ReturnDest::Store(dst) => (dst, &llargs[..]),
 516                             ReturnDest::DirectOperand(_) =>
 517                                 bug!("Cannot use direct operand with an intrinsic call")
 518                         };
 519
 520                         bcx.with_block(|bcx| {
 521                             trans_intrinsic_call(bcx, callee.ty, &fn_ty,
 522                                                  &llargs, dest, debug_loc);
 523                         });
 524
 525                         if let ReturnDest::IndirectOperand(dst, _) = ret_dest {
 526                             // Make a fake operand for store_return
 527                             let op = OperandRef {
 528                                 val: Ref(dst),
 529                                 ty: sig.output,
 530                             };
 531                             self.store_return(&bcx, ret_dest, fn_ty.ret, op);
 532                         }
 533
 534                         if let Some((_, target)) = *destination {
 535                             funclet_br(self, bcx, target);
 536                         } else {
 537                             // trans_intrinsic_call already used Unreachable.
 538                             // bcx.unreachable();
 539                         }
 540
 541                         return;
 542                     }
 543                     Fn(f) => f,
 544                     Virtual(_) => bug!("Virtual fn ptr not extracted")
 545                 };
 546
 547                 // Many different ways to call a function handled here
 548                 if let &Some(cleanup) = cleanup {
 549                     let ret_bcx = if let Some((_, target)) = *destination {
 550                         self.blocks[target]
 551                     } else {
 552                         self.unreachable_block()
 553                     };
 554                     let invokeret = bcx.invoke(fn_ptr,
 555                                                &llargs,
 556                                                ret_bcx.llbb,
 557                                                llblock(self, cleanup),
 558                                                cleanup_bundle);
 559                     fn_ty.apply_attrs_callsite(invokeret);
 560
 561                     if destination.is_some() {
 562                         let ret_bcx = ret_bcx.build();
 563                         ret_bcx.at_start(|ret_bcx| {
 564                             debug_loc.apply_to_bcx(ret_bcx);
 565                             let op = OperandRef {
 566                                 val: Immediate(invokeret),
 567                                 ty: sig.output,
 568                             };
 569                             self.store_return(&ret_bcx, ret_dest, fn_ty.ret, op);
 570                         });
 571                     }
 572                 } else {
 573                     let llret = bcx.call(fn_ptr, &llargs, cleanup_bundle);
 574                     fn_ty.apply_attrs_callsite(llret);
 575                     if let Some((_, target)) = *destination {
 576                         let op = OperandRef {
 577                             val: Immediate(llret),
 578                             ty: sig.output,
 579                         };
 580                         self.store_return(&bcx, ret_dest, fn_ty.ret, op);
 581                         funclet_br(self, bcx, target);
 582                     } else {
 583                         bcx.unreachable();
 584                     }
 585                 }
 586             }
 587         }
 588     }
 589
 590     fn trans_argument(&mut self,
 591                       bcx: &BlockAndBuilder<'bcx, 'tcx>,
 592                       op: OperandRef<'tcx>,
 593                       llargs: &mut Vec<ValueRef>,
 594                       fn_ty: &FnType,
 595                       next_idx: &mut usize,
 596                       callee: &mut CalleeData) {
 597         if let Pair(a, b) = op.val {
 598             // Treat the values in a fat pointer separately.
 599             if common::type_is_fat_ptr(bcx.tcx(), op.ty) {
 600                 let (ptr, meta) = (a, b);
 601                 if *next_idx == 0 {
 602                     if let Virtual(idx) = *callee {
 603                         let llfn = bcx.with_block(|bcx| {
 604                             meth::get_virtual_method(bcx, meta, idx)
 605                         });
 606                         let llty = fn_ty.llvm_type(bcx.ccx()).ptr_to();
 607                         *callee = Fn(bcx.pointercast(llfn, llty));
 608                     }
 609                 }
 610
 611                 let imm_op = |x| OperandRef {
 612                     val: Immediate(x),
 613                     // We won't be checking the type again.
 614                     ty: bcx.tcx().types.err
 615                 };
 616                 self.trans_argument(bcx, imm_op(ptr), llargs, fn_ty, next_idx, callee);
 617                 self.trans_argument(bcx, imm_op(meta), llargs, fn_ty, next_idx, callee);
 618                 return;
 619             }
 620         }
 621
 622         let arg = &fn_ty.args[*next_idx];
 623         *next_idx += 1;
 624
 625         // Fill padding with undef value, where applicable.
 626         if let Some(ty) = arg.pad {
 627             llargs.push(C_undef(ty));
 628         }
 629
 630         if arg.is_ignore() {
 631             return;
 632         }
 633
 634         // Force by-ref if we have to load through a cast pointer.
 635         let (mut llval, by_ref) = match op.val {
 636             Immediate(_) | Pair(..) => {
 637                 if arg.is_indirect() || arg.cast.is_some() {
 638                     let llscratch = build::AllocaFcx(bcx.fcx(), arg.original_ty, "arg");
 639                     self.store_operand(bcx, llscratch, op);
 640                     (llscratch, true)
 641                 } else {
 642                     (op.pack_if_pair(bcx).immediate(), false)
 643                 }
 644             }
 645             Ref(llval) => (llval, true)
 646         };
 647
 648         if by_ref && !arg.is_indirect() {
 649             // Have to load the argument, maybe while casting it.
 650             if arg.original_ty == Type::i1(bcx.ccx()) {
 651                 // We store bools as i8 so we need to truncate to i1.
 652                 llval = bcx.load_range_assert(llval, 0, 2, llvm::False);
 653                 llval = bcx.trunc(llval, arg.original_ty);
 654             } else if let Some(ty) = arg.cast {
 655                 llval = bcx.load(bcx.pointercast(llval, ty.ptr_to()));
 656                 let llalign = llalign_of_min(bcx.ccx(), arg.ty);
 657                 unsafe {
 658                     llvm::LLVMSetAlignment(llval, llalign);
 659                 }
 660             } else {
 661                 llval = bcx.load(llval);
 662             }
 663         }
 664
 665         llargs.push(llval);
 666     }
 667
 668     fn trans_arguments_untupled(&mut self,
 669                                 bcx: &BlockAndBuilder<'bcx, 'tcx>,
 670                                 operand: &mir::Operand<'tcx>,
 671                                 llargs: &mut Vec<ValueRef>,
 672                                 fn_ty: &FnType,
 673                                 next_idx: &mut usize,
 674                                 callee: &mut CalleeData) {
 675         let tuple = self.trans_operand(bcx, operand);
 676
 677         let arg_types = match tuple.ty.sty {
 678             ty::TyTuple(ref tys) => tys,
 679             _ => span_bug!(self.mir.span,
 680                            "bad final argument to \"rust-call\" fn {:?}", tuple.ty)
 681         };
 682
 683         // Handle both by-ref and immediate tuples.
 684         match tuple.val {
 685             Ref(llval) => {
 686                 let base_repr = adt::represent_type(bcx.ccx(), tuple.ty);
 687                 let base = adt::MaybeSizedValue::sized(llval);
 688                 for (n, &ty) in arg_types.iter().enumerate() {
 689                     let ptr = adt::trans_field_ptr_builder(bcx, &base_repr, base, Disr(0), n);
 690                     let val = if common::type_is_fat_ptr(bcx.tcx(), ty) {
 691                         let (lldata, llextra) = load_fat_ptr(bcx, ptr);
 692                         Pair(lldata, llextra)
 693                     } else {
 694                         // trans_argument will load this if it needs to
 695                         Ref(ptr)
 696                     };
 697                     let op = OperandRef {
 698                         val: val,
 699                         ty: ty
 700                     };
 701                     self.trans_argument(bcx, op, llargs, fn_ty, next_idx, callee);
 702                 }
 703
 704             }
 705             Immediate(llval) => {
 706                 for (n, &ty) in arg_types.iter().enumerate() {
 707                     let mut elem = bcx.extract_value(llval, n);
 708                     // Truncate bools to i1, if needed
 709                     if ty.is_bool() && common::val_ty(elem) != Type::i1(bcx.ccx()) {
 710                         elem = bcx.trunc(elem, Type::i1(bcx.ccx()));
 711                     }
 712                     // If the tuple is immediate, the elements are as well
 713                     let op = OperandRef {
 714                         val: Immediate(elem),
 715                         ty: ty
 716                     };
 717                     self.trans_argument(bcx, op, llargs, fn_ty, next_idx, callee);
 718                 }
 719             }
 720             Pair(a, b) => {
 721                 let elems = [a, b];
 722                 for (n, &ty) in arg_types.iter().enumerate() {
 723                     let mut elem = elems[n];
 724                     // Truncate bools to i1, if needed
 725                     if ty.is_bool() && common::val_ty(elem) != Type::i1(bcx.ccx()) {
 726                         elem = bcx.trunc(elem, Type::i1(bcx.ccx()));
 727                     }
 728                     // Pair is always made up of immediates
 729                     let op = OperandRef {
 730                         val: Immediate(elem),
 731                         ty: ty
 732                     };
 733                     self.trans_argument(bcx, op, llargs, fn_ty, next_idx, callee);
 734                 }
 735             }
 736         }
 737
 738     }
 739
 740     fn get_personality_slot(&mut self, bcx: &BlockAndBuilder<'bcx, 'tcx>) -> ValueRef {
 741         let ccx = bcx.ccx();
 742         if let Some(slot) = self.llpersonalityslot {
 743             slot
 744         } else {
 745             let llretty = Type::struct_(ccx, &[Type::i8p(ccx), Type::i32(ccx)], false);
 746             bcx.with_block(|bcx| {
 747                 let slot = base::alloca(bcx, llretty, "personalityslot");
 748                 self.llpersonalityslot = Some(slot);
 749                 base::call_lifetime_start(bcx, slot);
 750                 slot
 751             })
 752         }
 753     }
 754
 755     /// Return the landingpad wrapper around the given basic block
 756     ///
 757     /// No-op in MSVC SEH scheme.
 758     fn landing_pad_to(&mut self, target_bb: mir::BasicBlock) -> Block<'bcx, 'tcx>
 759     {
 760         if let Some(block) = self.landing_pads[target_bb] {
 761             return block;
 762         }
 763
 764         if base::wants_msvc_seh(self.fcx.ccx.sess()) {
 765             return self.blocks[target_bb];
 766         }
 767
 768         let target = self.bcx(target_bb);
 769
 770         let block = self.fcx.new_block("cleanup");
 771         self.landing_pads[target_bb] = Some(block);
 772
 773         let bcx = block.build();
 774         let ccx = bcx.ccx();
 775         let llpersonality = self.fcx.eh_personality();
 776         let llretty = Type::struct_(ccx, &[Type::i8p(ccx), Type::i32(ccx)], false);
 777         let llretval = bcx.landing_pad(llretty, llpersonality, 1, self.fcx.llfn);
 778         bcx.set_cleanup(llretval);
 779         let slot = self.get_personality_slot(&bcx);
 780         bcx.store(llretval, slot);
 781         bcx.br(target.llbb());
 782         block
 783     }
 784
 785     pub fn init_cpad(&mut self, bb: mir::BasicBlock) {
 786         let bcx = self.bcx(bb);
 787         let data = &self.mir[bb];
 788         debug!("init_cpad({:?})", data);
 789
 790         match self.cleanup_kinds[bb] {
 791             CleanupKind::NotCleanup => {
 792                 bcx.set_lpad(None)
 793             }
 794             _ if !base::wants_msvc_seh(bcx.sess()) => {
 795                 bcx.set_lpad(Some(LandingPad::gnu()))
 796             }
 797             CleanupKind::Internal { funclet } => {
 798                 // FIXME: is this needed?
 799                 bcx.set_personality_fn(self.fcx.eh_personality());
 800                 bcx.set_lpad_ref(self.bcx(funclet).lpad());
 801             }
 802             CleanupKind::Funclet => {
 803                 bcx.set_personality_fn(self.fcx.eh_personality());
 804                 DebugLoc::None.apply_to_bcx(&bcx);
 805                 let cleanup_pad = bcx.cleanup_pad(None, &[]);
 806                 bcx.set_lpad(Some(LandingPad::msvc(cleanup_pad)));
 807             }
 808         };
 809     }
 810
 811     fn unreachable_block(&mut self) -> Block<'bcx, 'tcx> {
 812         self.unreachable_block.unwrap_or_else(|| {
 813             let bl = self.fcx.new_block("unreachable");
 814             bl.build().unreachable();
 815             self.unreachable_block = Some(bl);
 816             bl
 817         })
 818     }
 819
 820     fn bcx(&self, bb: mir::BasicBlock) -> BlockAndBuilder<'bcx, 'tcx> {
 821         self.blocks[bb].build()
 822     }
 823
 824     fn make_return_dest(&mut self, bcx: &BlockAndBuilder<'bcx, 'tcx>,
 825                         dest: &mir::Lvalue<'tcx>, fn_ret_ty: &ArgType,
 826                         llargs: &mut Vec<ValueRef>, is_intrinsic: bool) -> ReturnDest {
 827         // If the return is ignored, we can just return a do-nothing ReturnDest
 828         if fn_ret_ty.is_ignore() {
 829             return ReturnDest::Nothing;
 830         }
 831         let dest = if let Some(index) = self.mir.local_index(dest) {
 832             let ret_ty = self.monomorphized_lvalue_ty(dest);
 833             match self.locals[index] {
 834                 LocalRef::Lvalue(dest) => dest,
 835                 LocalRef::Operand(None) => {
 836                     // Handle temporary lvalues, specifically Operand ones, as
 837                     // they don't have allocas
 838                     return if fn_ret_ty.is_indirect() {
 839                         // Odd, but possible, case, we have an operand temporary,
 840                         // but the calling convention has an indirect return.
 841                         let tmp = bcx.with_block(|bcx| {
 842                             base::alloc_ty(bcx, ret_ty, "tmp_ret")
 843                         });
 844                         llargs.push(tmp);
 845                         ReturnDest::IndirectOperand(tmp, index)
 846                     } else if is_intrinsic {
 847                         // Currently, intrinsics always need a location to store
 848                         // the result. so we create a temporary alloca for the
 849                         // result
 850                         let tmp = bcx.with_block(|bcx| {
 851                             base::alloc_ty(bcx, ret_ty, "tmp_ret")
 852                         });
 853                         ReturnDest::IndirectOperand(tmp, index)
 854                     } else {
 855                         ReturnDest::DirectOperand(index)
 856                     };
 857                 }
 858                 LocalRef::Operand(Some(_)) => {
 859                     bug!("lvalue local already assigned to");
 860                 }
 861             }
 862         } else {
 863             self.trans_lvalue(bcx, dest)
 864         };
 865         if fn_ret_ty.is_indirect() {
 866             llargs.push(dest.llval);
 867             ReturnDest::Nothing
 868         } else {
 869             ReturnDest::Store(dest.llval)
 870         }
 871     }
 872
 873     fn trans_transmute(&mut self, bcx: &BlockAndBuilder<'bcx, 'tcx>,
 874                        src: &mir::Operand<'tcx>, dst: LvalueRef<'tcx>) {
 875         let mut val = self.trans_operand(bcx, src);
 876         if let ty::TyFnDef(def_id, substs, _) = val.ty.sty {
 877             let llouttype = type_of::type_of(bcx.ccx(), dst.ty.to_ty(bcx.tcx()));
 878             let out_type_size = llbitsize_of_real(bcx.ccx(), llouttype);
 879             if out_type_size != 0 {
 880                 // FIXME #19925 Remove this hack after a release cycle.
 881                 let f = Callee::def(bcx.ccx(), def_id, substs);
 882                 let ty = match f.ty.sty {
 883                     ty::TyFnDef(_, _, f) => bcx.tcx().mk_fn_ptr(f),
 884                     _ => f.ty
 885                 };
 886                 val = OperandRef {
 887                     val: Immediate(f.reify(bcx.ccx())),
 888                     ty: ty
 889                 };
 890             }
 891         }
 892
 893         let llty = type_of::type_of(bcx.ccx(), val.ty);
 894         let cast_ptr = bcx.pointercast(dst.llval, llty.ptr_to());
 895         self.store_operand(bcx, cast_ptr, val);
 896     }
 897
 898
 899     // Stores the return value of a function call into it's final location.
 900     fn store_return(&mut self,
 901                     bcx: &BlockAndBuilder<'bcx, 'tcx>,
 902                     dest: ReturnDest,
 903                     ret_ty: ArgType,
 904                     op: OperandRef<'tcx>) {
 905         use self::ReturnDest::*;
 906
 907         match dest {
 908             Nothing => (),
 909             Store(dst) => ret_ty.store(bcx, op.immediate(), dst),
 910             IndirectOperand(tmp, index) => {
 911                 let op = self.trans_load(bcx, tmp, op.ty);
 912                 self.locals[index] = LocalRef::Operand(Some(op));
 913             }
 914             DirectOperand(index) => {
 915                 // If there is a cast, we have to store and reload.
 916                 let op = if ret_ty.cast.is_some() {
 917                     let tmp = bcx.with_block(|bcx| {
 918                         base::alloc_ty(bcx, op.ty, "tmp_ret")
 919                     });
 920                     ret_ty.store(bcx, op.immediate(), tmp);
 921                     self.trans_load(bcx, tmp, op.ty)
 922                 } else {
 923                     op.unpack_if_pair(bcx)
 924                 };
 925                 self.locals[index] = LocalRef::Operand(Some(op));
 926             }
 927         }
 928     }
 929 }
 930
 931 enum ReturnDest {
 932     // Do nothing, the return value is indirect or ignored
 933     Nothing,
 934     // Store the return value to the pointer
 935     Store(ValueRef),
 936     // Stores an indirect return value to an operand local lvalue
 937     IndirectOperand(ValueRef, mir::Local),
 938     // Stores a direct return value to an operand local lvalue
 939     DirectOperand(mir::Local)
 940 }