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;
  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};
  39 use super::operand::OperandRef;
  40 use super::operand::OperandValue::{Pair, Ref, Immediate};
  41
  42 use std::cell::Ref as CellRef;
  43
  44 impl<'bcx, 'tcx> MirContext<'bcx, 'tcx> {
  45     pub fn trans_block(&mut self, bb: mir::BasicBlock) {
  46         let mut bcx = self.bcx(bb);
  47         let data = &CellRef::clone(&self.mir)[bb];
  48
  49         debug!("trans_block({:?}={:?})", bb, data);
  50
  51         // Create the cleanup bundle, if needed.
  52         let cleanup_pad = bcx.lpad().and_then(|lp| lp.cleanuppad());
  53         let cleanup_bundle = bcx.lpad().and_then(|l| l.bundle());
  54
  55         let funclet_br = |this: &Self, bcx: BlockAndBuilder, bb: mir::BasicBlock| {
  56             let lltarget = this.blocks[bb].llbb;
  57             if let Some(cp) = cleanup_pad {
  58                 match this.cleanup_kinds[bb] {
  59                     CleanupKind::Funclet => {
  60                         // micro-optimization: generate a `ret` rather than a jump
  61                         // to a return block
  62                         bcx.cleanup_ret(cp, Some(lltarget));
  63                     }
  64                     CleanupKind::Internal { .. } => bcx.br(lltarget),
  65                     CleanupKind::NotCleanup => bug!("jump from cleanup bb to bb {:?}", bb)
  66                 }
  67             } else {
  68                 bcx.br(lltarget);
  69             }
  70         };
  71
  72         let llblock = |this: &mut Self, target: mir::BasicBlock| {
  73             let lltarget = this.blocks[target].llbb;
  74
  75             if let Some(cp) = cleanup_pad {
  76                 match this.cleanup_kinds[target] {
  77                     CleanupKind::Funclet => {
  78                         // MSVC cross-funclet jump - need a trampoline
  79
  80                         debug!("llblock: creating cleanup trampoline for {:?}", target);
  81                         let name = &format!("{:?}_cleanup_trampoline_{:?}", bb, target);
  82                         let trampoline = this.fcx.new_block(name).build();
  83                         trampoline.set_personality_fn(this.fcx.eh_personality());
  84                         trampoline.cleanup_ret(cp, Some(lltarget));
  85                         trampoline.llbb()
  86                     }
  87                     CleanupKind::Internal { .. } => lltarget,
  88                     CleanupKind::NotCleanup =>
  89                         bug!("jump from cleanup bb {:?} to bb {:?}", bb, target)
  90                 }
  91             } else {
  92                 if let (CleanupKind::NotCleanup, CleanupKind::Funclet) =
  93                     (this.cleanup_kinds[bb], this.cleanup_kinds[target])
  94                 {
  95                     // jump *into* cleanup - need a landing pad if GNU
  96                     this.landing_pad_to(target).llbb
  97                 } else {
  98                     lltarget
  99                 }
 100             }
 101         };
 102
 103         for statement in &data.statements {
 104             bcx = self.trans_statement(bcx, statement);
 105         }
 106
 107         let terminator = data.terminator();
 108         debug!("trans_block: terminator: {:?}", terminator);
 109
 110         let span = terminator.source_info.span;
 111         let debug_loc = self.debug_loc(terminator.source_info);
 112         debug_loc.apply_to_bcx(&bcx);
 113         debug_loc.apply(bcx.fcx());
 114         match terminator.kind {
 115             mir::TerminatorKind::Resume => {
 116                 if let Some(cleanup_pad) = cleanup_pad {
 117                     bcx.cleanup_ret(cleanup_pad, None);
 118                 } else {
 119                     let ps = self.get_personality_slot(&bcx);
 120                     let lp = bcx.load(ps);
 121                     bcx.with_block(|bcx| {
 122                         base::call_lifetime_end(bcx, ps);
 123                         base::trans_unwind_resume(bcx, lp);
 124                     });
 125                 }
 126             }
 127
 128             mir::TerminatorKind::Goto { target } => {
 129                 funclet_br(self, bcx, target);
 130             }
 131
 132             mir::TerminatorKind::If { ref cond, targets: (true_bb, false_bb) } => {
 133                 let cond = self.trans_operand(&bcx, cond);
 134
 135                 let lltrue = llblock(self, true_bb);
 136                 let llfalse = llblock(self, false_bb);
 137                 bcx.cond_br(cond.immediate(), lltrue, llfalse);
 138             }
 139
 140             mir::TerminatorKind::Switch { ref discr, ref adt_def, ref targets } => {
 141                 let discr_lvalue = self.trans_lvalue(&bcx, discr);
 142                 let ty = discr_lvalue.ty.to_ty(bcx.tcx());
 143                 let discr = bcx.with_block(|bcx|
 144                     adt::trans_get_discr(bcx, ty, 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, ty, 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 op = match self.locals[mir::RETURN_POINTER] {
 197                         LocalRef::Operand(Some(op)) => op,
 198                         LocalRef::Operand(None) => bug!("use of return before def"),
 199                         LocalRef::Lvalue(tr_lvalue) => {
 200                             OperandRef {
 201                                 val: Ref(tr_lvalue.llval),
 202                                 ty: tr_lvalue.ty.to_ty(bcx.tcx())
 203                             }
 204                         }
 205                     };
 206                     let llslot = match op.val {
 207                         Immediate(_) | Pair(..) => {
 208                             let llscratch = build::AllocaFcx(bcx.fcx(), ret.original_ty, "ret");
 209                             self.store_operand(&bcx, llscratch, op);
 210                             llscratch
 211                         }
 212                         Ref(llval) => llval
 213                     };
 214                     let load = bcx.load(bcx.pointercast(llslot, cast_ty.ptr_to()));
 215                     let llalign = llalign_of_min(bcx.ccx(), ret.ty);
 216                     unsafe {
 217                         llvm::LLVMSetAlignment(load, llalign);
 218                     }
 219                     load
 220                 } else {
 221                     let op = self.trans_consume(&bcx, &mir::Lvalue::Local(mir::RETURN_POINTER));
 222                     op.pack_if_pair(&bcx).immediate()
 223                 };
 224                 bcx.ret(llval);
 225             }
 226
 227             mir::TerminatorKind::Unreachable => {
 228                 bcx.unreachable();
 229             }
 230
 231             mir::TerminatorKind::Drop { ref location, target, unwind } => {
 232                 let ty = location.ty(&self.mir, bcx.tcx()).to_ty(bcx.tcx());
 233                 let ty = bcx.monomorphize(&ty);
 234
 235                 // Double check for necessity to drop
 236                 if !glue::type_needs_drop(bcx.tcx(), ty) {
 237                     funclet_br(self, bcx, target);
 238                     return;
 239                 }
 240
 241                 let lvalue = self.trans_lvalue(&bcx, location);
 242                 let drop_fn = glue::get_drop_glue(bcx.ccx(), ty);
 243                 let drop_ty = glue::get_drop_glue_type(bcx.tcx(), ty);
 244                 let is_sized = common::type_is_sized(bcx.tcx(), ty);
 245                 let llvalue = if is_sized {
 246                     if drop_ty != ty {
 247                         bcx.pointercast(lvalue.llval, type_of::type_of(bcx.ccx(), drop_ty).ptr_to())
 248                     } else {
 249                         lvalue.llval
 250                     }
 251                 } else {
 252                     // FIXME(#36457) Currently drop glue takes sized
 253                     // values as a `*(data, meta)`, but elsewhere in
 254                     // MIR we pass `(data, meta)` as two separate
 255                     // arguments. It would be better to fix drop glue,
 256                     // but I am shooting for a quick fix to #35546
 257                     // here that can be cleanly backported to beta, so
 258                     // I want to avoid touching all of trans.
 259                     bcx.with_block(|bcx| {
 260                         let scratch = base::alloc_ty(bcx, ty, "drop");
 261                         base::call_lifetime_start(bcx, scratch);
 262                         build::Store(bcx, lvalue.llval, base::get_dataptr(bcx, scratch));
 263                         build::Store(bcx, lvalue.llextra, base::get_meta(bcx, scratch));
 264                         scratch
 265                     })
 266                 };
 267                 if let Some(unwind) = unwind {
 268                     bcx.invoke(drop_fn,
 269                                &[llvalue],
 270                                self.blocks[target].llbb,
 271                                llblock(self, unwind),
 272                                cleanup_bundle);
 273                 } else {
 274                     bcx.call(drop_fn, &[llvalue], cleanup_bundle);
 275                     funclet_br(self, bcx, target);
 276                 }
 277             }
 278
 279             mir::TerminatorKind::Assert { ref cond, expected, ref msg, target, cleanup } => {
 280                 let cond = self.trans_operand(&bcx, cond).immediate();
 281                 let mut const_cond = common::const_to_opt_uint(cond).map(|c| c == 1);
 282
 283                 // This case can currently arise only from functions marked
 284                 // with #[rustc_inherit_overflow_checks] and inlined from
 285                 // another crate (mostly core::num generic/#[inline] fns),
 286                 // while the current crate doesn't use overflow checks.
 287                 // NOTE: Unlike binops, negation doesn't have its own
 288                 // checked operation, just a comparison with the minimum
 289                 // value, so we have to check for the assert message.
 290                 if !bcx.ccx().check_overflow() {
 291                     use rustc_const_math::ConstMathErr::Overflow;
 292                     use rustc_const_math::Op::Neg;
 293
 294                     if let mir::AssertMessage::Math(Overflow(Neg)) = *msg {
 295                         const_cond = Some(expected);
 296                     }
 297                 }
 298
 299                 // Don't translate the panic block if success if known.
 300                 if const_cond == Some(expected) {
 301                     funclet_br(self, bcx, target);
 302                     return;
 303                 }
 304
 305                 // Pass the condition through llvm.expect for branch hinting.
 306                 let expect = bcx.ccx().get_intrinsic(&"llvm.expect.i1");
 307                 let cond = bcx.call(expect, &[cond, C_bool(bcx.ccx(), expected)], None);
 308
 309                 // Create the failure block and the conditional branch to it.
 310                 let lltarget = llblock(self, target);
 311                 let panic_block = self.fcx.new_block("panic");
 312                 if expected {
 313                     bcx.cond_br(cond, lltarget, panic_block.llbb);
 314                 } else {
 315                     bcx.cond_br(cond, panic_block.llbb, lltarget);
 316                 }
 317
 318                 // After this point, bcx is the block for the call to panic.
 319                 bcx = panic_block.build();
 320                 debug_loc.apply_to_bcx(&bcx);
 321
 322                 // Get the location information.
 323                 let loc = bcx.sess().codemap().lookup_char_pos(span.lo);
 324                 let filename = token::intern_and_get_ident(&loc.file.name);
 325                 let filename = C_str_slice(bcx.ccx(), filename);
 326                 let line = C_u32(bcx.ccx(), loc.line as u32);
 327
 328                 // Put together the arguments to the panic entry point.
 329                 let (lang_item, args, const_err) = match *msg {
 330                     mir::AssertMessage::BoundsCheck { ref len, ref index } => {
 331                         let len = self.trans_operand(&mut bcx, len).immediate();
 332                         let index = self.trans_operand(&mut bcx, index).immediate();
 333
 334                         let const_err = common::const_to_opt_uint(len).and_then(|len| {
 335                             common::const_to_opt_uint(index).map(|index| {
 336                                 ErrKind::IndexOutOfBounds {
 337                                     len: len,
 338                                     index: index
 339                                 }
 340                             })
 341                         });
 342
 343                         let file_line = C_struct(bcx.ccx(), &[filename, line], false);
 344                         let align = llalign_of_min(bcx.ccx(), common::val_ty(file_line));
 345                         let file_line = consts::addr_of(bcx.ccx(),
 346                                                         file_line,
 347                                                         align,
 348                                                         "panic_bounds_check_loc");
 349                         (lang_items::PanicBoundsCheckFnLangItem,
 350                          vec![file_line, index, len],
 351                          const_err)
 352                     }
 353                     mir::AssertMessage::Math(ref err) => {
 354                         let msg_str = token::intern_and_get_ident(err.description());
 355                         let msg_str = C_str_slice(bcx.ccx(), msg_str);
 356                         let msg_file_line = C_struct(bcx.ccx(),
 357                                                      &[msg_str, filename, line],
 358                                                      false);
 359                         let align = llalign_of_min(bcx.ccx(), common::val_ty(msg_file_line));
 360                         let msg_file_line = consts::addr_of(bcx.ccx(),
 361                                                             msg_file_line,
 362                                                             align,
 363                                                             "panic_loc");
 364                         (lang_items::PanicFnLangItem,
 365                          vec![msg_file_line],
 366                          Some(ErrKind::Math(err.clone())))
 367                     }
 368                 };
 369
 370                 // If we know we always panic, and the error message
 371                 // is also constant, then we can produce a warning.
 372                 if const_cond == Some(!expected) {
 373                     if let Some(err) = const_err {
 374                         let err = ConstEvalErr{ span: span, kind: err };
 375                         let mut diag = bcx.tcx().sess.struct_span_warn(
 376                             span, "this expression will panic at run-time");
 377                         note_const_eval_err(bcx.tcx(), &err, span, "expression", &mut diag);
 378                         diag.emit();
 379                     }
 380                 }
 381
 382                 // Obtain the panic entry point.
 383                 let def_id = common::langcall(bcx.tcx(), Some(span), "", lang_item);
 384                 let callee = Callee::def(bcx.ccx(), def_id,
 385                     bcx.ccx().empty_substs_for_def_id(def_id));
 386                 let llfn = callee.reify(bcx.ccx());
 387
 388                 // Translate the actual panic invoke/call.
 389                 if let Some(unwind) = cleanup {
 390                     bcx.invoke(llfn,
 391                                &args,
 392                                self.unreachable_block().llbb,
 393                                llblock(self, unwind),
 394                                cleanup_bundle);
 395                 } else {
 396                     bcx.call(llfn, &args, cleanup_bundle);
 397                     bcx.unreachable();
 398                 }
 399             }
 400
 401             mir::TerminatorKind::DropAndReplace { .. } => {
 402                 bug!("undesugared DropAndReplace in trans: {:?}", data);
 403             }
 404
 405             mir::TerminatorKind::Call { ref func, ref args, ref destination, ref cleanup } => {
 406                 // Create the callee. This is a fn ptr or zero-sized and hence a kind of scalar.
 407                 let callee = self.trans_operand(&bcx, func);
 408
 409                 let (mut callee, abi, sig) = match callee.ty.sty {
 410                     ty::TyFnDef(def_id, substs, f) => {
 411                         (Callee::def(bcx.ccx(), def_id, substs), f.abi, &f.sig)
 412                     }
 413                     ty::TyFnPtr(f) => {
 414                         (Callee {
 415                             data: Fn(callee.immediate()),
 416                             ty: callee.ty
 417                         }, f.abi, &f.sig)
 418                     }
 419                     _ => bug!("{} is not callable", callee.ty)
 420                 };
 421
 422                 let sig = bcx.tcx().erase_late_bound_regions_and_normalize(sig);
 423
 424                 // Handle intrinsics old trans wants Expr's for, ourselves.
 425                 let intrinsic = match (&callee.ty.sty, &callee.data) {
 426                     (&ty::TyFnDef(def_id, ..), &Intrinsic) => {
 427                         Some(bcx.tcx().item_name(def_id).as_str())
 428                     }
 429                     _ => None
 430                 };
 431                 let intrinsic = intrinsic.as_ref().map(|s| &s[..]);
 432
 433                 if intrinsic == Some("move_val_init") {
 434                     let &(_, target) = destination.as_ref().unwrap();
 435                     // The first argument is a thin destination pointer.
 436                     let llptr = self.trans_operand(&bcx, &args[0]).immediate();
 437                     let val = self.trans_operand(&bcx, &args[1]);
 438                     self.store_operand(&bcx, llptr, val);
 439                     funclet_br(self, bcx, target);
 440                     return;
 441                 }
 442
 443                 if intrinsic == Some("transmute") {
 444                     let &(ref dest, target) = destination.as_ref().unwrap();
 445                     self.with_lvalue_ref(&bcx, dest, |this, dest| {
 446                         this.trans_transmute(&bcx, &args[0], dest);
 447                     });
 448
 449                     funclet_br(self, bcx, target);
 450                     return;
 451                 }
 452
 453                 let extra_args = &args[sig.inputs.len()..];
 454                 let extra_args = extra_args.iter().map(|op_arg| {
 455                     let op_ty = op_arg.ty(&self.mir, bcx.tcx());
 456                     bcx.monomorphize(&op_ty)
 457                 }).collect::<Vec<_>>();
 458                 let fn_ty = callee.direct_fn_type(bcx.ccx(), &extra_args);
 459
 460                 // The arguments we'll be passing. Plus one to account for outptr, if used.
 461                 let arg_count = fn_ty.args.len() + fn_ty.ret.is_indirect() as usize;
 462                 let mut llargs = Vec::with_capacity(arg_count);
 463
 464                 // Prepare the return value destination
 465                 let ret_dest = if let Some((ref dest, _)) = *destination {
 466                     let is_intrinsic = if let Intrinsic = callee.data {
 467                         true
 468                     } else {
 469                         false
 470                     };
 471                     self.make_return_dest(&bcx, dest, &fn_ty.ret, &mut llargs, is_intrinsic)
 472                 } else {
 473                     ReturnDest::Nothing
 474                 };
 475
 476                 // Split the rust-call tupled arguments off.
 477                 let (first_args, untuple) = if abi == Abi::RustCall && !args.is_empty() {
 478                     let (tup, args) = args.split_last().unwrap();
 479                     (args, Some(tup))
 480                 } else {
 481                     (&args[..], None)
 482                 };
 483
 484                 let is_shuffle = intrinsic.map_or(false, |name| {
 485                     name.starts_with("simd_shuffle")
 486                 });
 487                 let mut idx = 0;
 488                 for arg in first_args {
 489                     // The indices passed to simd_shuffle* in the
 490                     // third argument must be constant. This is
 491                     // checked by const-qualification, which also
 492                     // promotes any complex rvalues to constants.
 493                     if is_shuffle && idx == 2 {
 494                         match *arg {
 495                             mir::Operand::Consume(_) => {
 496                                 span_bug!(span, "shuffle indices must be constant");
 497                             }
 498                             mir::Operand::Constant(ref constant) => {
 499                                 let val = self.trans_constant(&bcx, constant);
 500                                 llargs.push(val.llval);
 501                                 idx += 1;
 502                                 continue;
 503                             }
 504                         }
 505                     }
 506
 507                     let op = self.trans_operand(&bcx, arg);
 508                     self.trans_argument(&bcx, op, &mut llargs, &fn_ty,
 509                                         &mut idx, &mut callee.data);
 510                 }
 511                 if let Some(tup) = untuple {
 512                     self.trans_arguments_untupled(&bcx, tup, &mut llargs, &fn_ty,
 513                                                   &mut idx, &mut callee.data)
 514                 }
 515
 516                 let fn_ptr = match callee.data {
 517                     NamedTupleConstructor(_) => {
 518                         // FIXME translate this like mir::Rvalue::Aggregate.
 519                         callee.reify(bcx.ccx())
 520                     }
 521                     Intrinsic => {
 522                         use intrinsic::trans_intrinsic_call;
 523
 524                         let (dest, llargs) = match ret_dest {
 525                             _ if fn_ty.ret.is_indirect() => {
 526                                 (llargs[0], &llargs[1..])
 527                             }
 528                             ReturnDest::Nothing => {
 529                                 (C_undef(fn_ty.ret.original_ty.ptr_to()), &llargs[..])
 530                             }
 531                             ReturnDest::IndirectOperand(dst, _) |
 532                             ReturnDest::Store(dst) => (dst, &llargs[..]),
 533                             ReturnDest::DirectOperand(_) =>
 534                                 bug!("Cannot use direct operand with an intrinsic call")
 535                         };
 536
 537                         bcx.with_block(|bcx| {
 538                             trans_intrinsic_call(bcx, callee.ty, &fn_ty,
 539                                                  &llargs, dest, debug_loc);
 540                         });
 541
 542                         if let ReturnDest::IndirectOperand(dst, _) = ret_dest {
 543                             // Make a fake operand for store_return
 544                             let op = OperandRef {
 545                                 val: Ref(dst),
 546                                 ty: sig.output,
 547                             };
 548                             self.store_return(&bcx, ret_dest, fn_ty.ret, op);
 549                         }
 550
 551                         if let Some((_, target)) = *destination {
 552                             funclet_br(self, bcx, target);
 553                         } else {
 554                             // trans_intrinsic_call already used Unreachable.
 555                             // bcx.unreachable();
 556                         }
 557
 558                         return;
 559                     }
 560                     Fn(f) => f,
 561                     Virtual(_) => bug!("Virtual fn ptr not extracted")
 562                 };
 563
 564                 // Many different ways to call a function handled here
 565                 if let &Some(cleanup) = cleanup {
 566                     let ret_bcx = if let Some((_, target)) = *destination {
 567                         self.blocks[target]
 568                     } else {
 569                         self.unreachable_block()
 570                     };
 571                     let invokeret = bcx.invoke(fn_ptr,
 572                                                &llargs,
 573                                                ret_bcx.llbb,
 574                                                llblock(self, cleanup),
 575                                                cleanup_bundle);
 576                     fn_ty.apply_attrs_callsite(invokeret);
 577
 578                     if destination.is_some() {
 579                         let ret_bcx = ret_bcx.build();
 580                         ret_bcx.at_start(|ret_bcx| {
 581                             debug_loc.apply_to_bcx(ret_bcx);
 582                             let op = OperandRef {
 583                                 val: Immediate(invokeret),
 584                                 ty: sig.output,
 585                             };
 586                             self.store_return(&ret_bcx, ret_dest, fn_ty.ret, op);
 587                         });
 588                     }
 589                 } else {
 590                     let llret = bcx.call(fn_ptr, &llargs, cleanup_bundle);
 591                     fn_ty.apply_attrs_callsite(llret);
 592                     if let Some((_, target)) = *destination {
 593                         let op = OperandRef {
 594                             val: Immediate(llret),
 595                             ty: sig.output,
 596                         };
 597                         self.store_return(&bcx, ret_dest, fn_ty.ret, op);
 598                         funclet_br(self, bcx, target);
 599                     } else {
 600                         bcx.unreachable();
 601                     }
 602                 }
 603             }
 604         }
 605     }
 606
 607     fn trans_argument(&mut self,
 608                       bcx: &BlockAndBuilder<'bcx, 'tcx>,
 609                       op: OperandRef<'tcx>,
 610                       llargs: &mut Vec<ValueRef>,
 611                       fn_ty: &FnType,
 612                       next_idx: &mut usize,
 613                       callee: &mut CalleeData) {
 614         if let Pair(a, b) = op.val {
 615             // Treat the values in a fat pointer separately.
 616             if common::type_is_fat_ptr(bcx.tcx(), op.ty) {
 617                 let (ptr, meta) = (a, b);
 618                 if *next_idx == 0 {
 619                     if let Virtual(idx) = *callee {
 620                         let llfn = bcx.with_block(|bcx| {
 621                             meth::get_virtual_method(bcx, meta, idx)
 622                         });
 623                         let llty = fn_ty.llvm_type(bcx.ccx()).ptr_to();
 624                         *callee = Fn(bcx.pointercast(llfn, llty));
 625                     }
 626                 }
 627
 628                 let imm_op = |x| OperandRef {
 629                     val: Immediate(x),
 630                     // We won't be checking the type again.
 631                     ty: bcx.tcx().types.err
 632                 };
 633                 self.trans_argument(bcx, imm_op(ptr), llargs, fn_ty, next_idx, callee);
 634                 self.trans_argument(bcx, imm_op(meta), llargs, fn_ty, next_idx, callee);
 635                 return;
 636             }
 637         }
 638
 639         let arg = &fn_ty.args[*next_idx];
 640         *next_idx += 1;
 641
 642         // Fill padding with undef value, where applicable.
 643         if let Some(ty) = arg.pad {
 644             llargs.push(C_undef(ty));
 645         }
 646
 647         if arg.is_ignore() {
 648             return;
 649         }
 650
 651         // Force by-ref if we have to load through a cast pointer.
 652         let (mut llval, by_ref) = match op.val {
 653             Immediate(_) | Pair(..) => {
 654                 if arg.is_indirect() || arg.cast.is_some() {
 655                     let llscratch = build::AllocaFcx(bcx.fcx(), arg.original_ty, "arg");
 656                     self.store_operand(bcx, llscratch, op);
 657                     (llscratch, true)
 658                 } else {
 659                     (op.pack_if_pair(bcx).immediate(), false)
 660                 }
 661             }
 662             Ref(llval) => (llval, true)
 663         };
 664
 665         if by_ref && !arg.is_indirect() {
 666             // Have to load the argument, maybe while casting it.
 667             if arg.original_ty == Type::i1(bcx.ccx()) {
 668                 // We store bools as i8 so we need to truncate to i1.
 669                 llval = bcx.load_range_assert(llval, 0, 2, llvm::False);
 670                 llval = bcx.trunc(llval, arg.original_ty);
 671             } else if let Some(ty) = arg.cast {
 672                 llval = bcx.load(bcx.pointercast(llval, ty.ptr_to()));
 673                 let llalign = llalign_of_min(bcx.ccx(), arg.ty);
 674                 unsafe {
 675                     llvm::LLVMSetAlignment(llval, llalign);
 676                 }
 677             } else {
 678                 llval = bcx.load(llval);
 679             }
 680         }
 681
 682         llargs.push(llval);
 683     }
 684
 685     fn trans_arguments_untupled(&mut self,
 686                                 bcx: &BlockAndBuilder<'bcx, 'tcx>,
 687                                 operand: &mir::Operand<'tcx>,
 688                                 llargs: &mut Vec<ValueRef>,
 689                                 fn_ty: &FnType,
 690                                 next_idx: &mut usize,
 691                                 callee: &mut CalleeData) {
 692         let tuple = self.trans_operand(bcx, operand);
 693
 694         let arg_types = match tuple.ty.sty {
 695             ty::TyTuple(ref tys) => tys,
 696             _ => span_bug!(self.mir.span,
 697                            "bad final argument to \"rust-call\" fn {:?}", tuple.ty)
 698         };
 699
 700         // Handle both by-ref and immediate tuples.
 701         match tuple.val {
 702             Ref(llval) => {
 703                 let base = adt::MaybeSizedValue::sized(llval);
 704                 for (n, &ty) in arg_types.iter().enumerate() {
 705                     let ptr = adt::trans_field_ptr_builder(bcx, tuple.ty, base, Disr(0), n);
 706                     let val = if common::type_is_fat_ptr(bcx.tcx(), ty) {
 707                         let (lldata, llextra) = base::load_fat_ptr_builder(bcx, ptr, ty);
 708                         Pair(lldata, llextra)
 709                     } else {
 710                         // trans_argument will load this if it needs to
 711                         Ref(ptr)
 712                     };
 713                     let op = OperandRef {
 714                         val: val,
 715                         ty: ty
 716                     };
 717                     self.trans_argument(bcx, op, llargs, fn_ty, next_idx, callee);
 718                 }
 719
 720             }
 721             Immediate(llval) => {
 722                 for (n, &ty) in arg_types.iter().enumerate() {
 723                     let mut elem = bcx.extract_value(llval, 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                     // If the tuple is immediate, the elements are as well
 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             Pair(a, b) => {
 737                 let elems = [a, b];
 738                 for (n, &ty) in arg_types.iter().enumerate() {
 739                     let mut elem = elems[n];
 740                     // Truncate bools to i1, if needed
 741                     if ty.is_bool() && common::val_ty(elem) != Type::i1(bcx.ccx()) {
 742                         elem = bcx.trunc(elem, Type::i1(bcx.ccx()));
 743                     }
 744                     // Pair is always made up of immediates
 745                     let op = OperandRef {
 746                         val: Immediate(elem),
 747                         ty: ty
 748                     };
 749                     self.trans_argument(bcx, op, llargs, fn_ty, next_idx, callee);
 750                 }
 751             }
 752         }
 753
 754     }
 755
 756     fn get_personality_slot(&mut self, bcx: &BlockAndBuilder<'bcx, 'tcx>) -> ValueRef {
 757         let ccx = bcx.ccx();
 758         if let Some(slot) = self.llpersonalityslot {
 759             slot
 760         } else {
 761             let llretty = Type::struct_(ccx, &[Type::i8p(ccx), Type::i32(ccx)], false);
 762             bcx.with_block(|bcx| {
 763                 let slot = base::alloca(bcx, llretty, "personalityslot");
 764                 self.llpersonalityslot = Some(slot);
 765                 base::call_lifetime_start(bcx, slot);
 766                 slot
 767             })
 768         }
 769     }
 770
 771     /// Return the landingpad wrapper around the given basic block
 772     ///
 773     /// No-op in MSVC SEH scheme.
 774     fn landing_pad_to(&mut self, target_bb: mir::BasicBlock) -> Block<'bcx, 'tcx>
 775     {
 776         if let Some(block) = self.landing_pads[target_bb] {
 777             return block;
 778         }
 779
 780         if base::wants_msvc_seh(self.fcx.ccx.sess()) {
 781             return self.blocks[target_bb];
 782         }
 783
 784         let target = self.bcx(target_bb);
 785
 786         let block = self.fcx.new_block("cleanup");
 787         self.landing_pads[target_bb] = Some(block);
 788
 789         let bcx = block.build();
 790         let ccx = bcx.ccx();
 791         let llpersonality = self.fcx.eh_personality();
 792         let llretty = Type::struct_(ccx, &[Type::i8p(ccx), Type::i32(ccx)], false);
 793         let llretval = bcx.landing_pad(llretty, llpersonality, 1, self.fcx.llfn);
 794         bcx.set_cleanup(llretval);
 795         let slot = self.get_personality_slot(&bcx);
 796         bcx.store(llretval, slot);
 797         bcx.br(target.llbb());
 798         block
 799     }
 800
 801     pub fn init_cpad(&mut self, bb: mir::BasicBlock) {
 802         let bcx = self.bcx(bb);
 803         let data = &self.mir[bb];
 804         debug!("init_cpad({:?})", data);
 805
 806         match self.cleanup_kinds[bb] {
 807             CleanupKind::NotCleanup => {
 808                 bcx.set_lpad(None)
 809             }
 810             _ if !base::wants_msvc_seh(bcx.sess()) => {
 811                 bcx.set_lpad(Some(LandingPad::gnu()))
 812             }
 813             CleanupKind::Internal { funclet } => {
 814                 // FIXME: is this needed?
 815                 bcx.set_personality_fn(self.fcx.eh_personality());
 816                 bcx.set_lpad_ref(self.bcx(funclet).lpad());
 817             }
 818             CleanupKind::Funclet => {
 819                 bcx.set_personality_fn(self.fcx.eh_personality());
 820                 DebugLoc::None.apply_to_bcx(&bcx);
 821                 let cleanup_pad = bcx.cleanup_pad(None, &[]);
 822                 bcx.set_lpad(Some(LandingPad::msvc(cleanup_pad)));
 823             }
 824         };
 825     }
 826
 827     fn unreachable_block(&mut self) -> Block<'bcx, 'tcx> {
 828         self.unreachable_block.unwrap_or_else(|| {
 829             let bl = self.fcx.new_block("unreachable");
 830             bl.build().unreachable();
 831             self.unreachable_block = Some(bl);
 832             bl
 833         })
 834     }
 835
 836     fn bcx(&self, bb: mir::BasicBlock) -> BlockAndBuilder<'bcx, 'tcx> {
 837         self.blocks[bb].build()
 838     }
 839
 840     fn make_return_dest(&mut self, bcx: &BlockAndBuilder<'bcx, 'tcx>,
 841                         dest: &mir::Lvalue<'tcx>, fn_ret_ty: &ArgType,
 842                         llargs: &mut Vec<ValueRef>, is_intrinsic: bool) -> ReturnDest {
 843         // If the return is ignored, we can just return a do-nothing ReturnDest
 844         if fn_ret_ty.is_ignore() {
 845             return ReturnDest::Nothing;
 846         }
 847         let dest = if let mir::Lvalue::Local(index) = *dest {
 848             let ret_ty = self.monomorphized_lvalue_ty(dest);
 849             match self.locals[index] {
 850                 LocalRef::Lvalue(dest) => dest,
 851                 LocalRef::Operand(None) => {
 852                     // Handle temporary lvalues, specifically Operand ones, as
 853                     // they don't have allocas
 854                     return if fn_ret_ty.is_indirect() {
 855                         // Odd, but possible, case, we have an operand temporary,
 856                         // but the calling convention has an indirect return.
 857                         let tmp = bcx.with_block(|bcx| {
 858                             base::alloc_ty(bcx, ret_ty, "tmp_ret")
 859                         });
 860                         llargs.push(tmp);
 861                         ReturnDest::IndirectOperand(tmp, index)
 862                     } else if is_intrinsic {
 863                         // Currently, intrinsics always need a location to store
 864                         // the result. so we create a temporary alloca for the
 865                         // result
 866                         let tmp = bcx.with_block(|bcx| {
 867                             base::alloc_ty(bcx, ret_ty, "tmp_ret")
 868                         });
 869                         ReturnDest::IndirectOperand(tmp, index)
 870                     } else {
 871                         ReturnDest::DirectOperand(index)
 872                     };
 873                 }
 874                 LocalRef::Operand(Some(_)) => {
 875                     bug!("lvalue local already assigned to");
 876                 }
 877             }
 878         } else {
 879             self.trans_lvalue(bcx, dest)
 880         };
 881         if fn_ret_ty.is_indirect() {
 882             llargs.push(dest.llval);
 883             ReturnDest::Nothing
 884         } else {
 885             ReturnDest::Store(dest.llval)
 886         }
 887     }
 888
 889     fn trans_transmute(&mut self, bcx: &BlockAndBuilder<'bcx, 'tcx>,
 890                        src: &mir::Operand<'tcx>, dst: LvalueRef<'tcx>) {
 891         let mut val = self.trans_operand(bcx, src);
 892         if let ty::TyFnDef(def_id, substs, _) = val.ty.sty {
 893             let llouttype = type_of::type_of(bcx.ccx(), dst.ty.to_ty(bcx.tcx()));
 894             let out_type_size = llbitsize_of_real(bcx.ccx(), llouttype);
 895             if out_type_size != 0 {
 896                 // FIXME #19925 Remove this hack after a release cycle.
 897                 let f = Callee::def(bcx.ccx(), def_id, substs);
 898                 let ty = match f.ty.sty {
 899                     ty::TyFnDef(.., f) => bcx.tcx().mk_fn_ptr(f),
 900                     _ => f.ty
 901                 };
 902                 val = OperandRef {
 903                     val: Immediate(f.reify(bcx.ccx())),
 904                     ty: ty
 905                 };
 906             }
 907         }
 908
 909         let llty = type_of::type_of(bcx.ccx(), val.ty);
 910         let cast_ptr = bcx.pointercast(dst.llval, llty.ptr_to());
 911         self.store_operand(bcx, cast_ptr, val);
 912     }
 913
 914
 915     // Stores the return value of a function call into it's final location.
 916     fn store_return(&mut self,
 917                     bcx: &BlockAndBuilder<'bcx, 'tcx>,
 918                     dest: ReturnDest,
 919                     ret_ty: ArgType,
 920                     op: OperandRef<'tcx>) {
 921         use self::ReturnDest::*;
 922
 923         match dest {
 924             Nothing => (),
 925             Store(dst) => ret_ty.store(bcx, op.immediate(), dst),
 926             IndirectOperand(tmp, index) => {
 927                 let op = self.trans_load(bcx, tmp, op.ty);
 928                 self.locals[index] = LocalRef::Operand(Some(op));
 929             }
 930             DirectOperand(index) => {
 931                 // If there is a cast, we have to store and reload.
 932                 let op = if ret_ty.cast.is_some() {
 933                     let tmp = bcx.with_block(|bcx| {
 934                         base::alloc_ty(bcx, op.ty, "tmp_ret")
 935                     });
 936                     ret_ty.store(bcx, op.immediate(), tmp);
 937                     self.trans_load(bcx, tmp, op.ty)
 938                 } else {
 939                     op.unpack_if_pair(bcx)
 940                 };
 941                 self.locals[index] = LocalRef::Operand(Some(op));
 942             }
 943         }
 944     }
 945 }
 946
 947 enum ReturnDest {
 948     // Do nothing, the return value is indirect or ignored
 949     Nothing,
 950     // Store the return value to the pointer
 951     Store(ValueRef),
 952     // Stores an indirect return value to an operand local lvalue
 953     IndirectOperand(ValueRef, mir::Local),
 954     // Stores a direct return value to an operand local lvalue
 955     DirectOperand(mir::Local)
 956 }