src/librustc_trans/mir/block.rs

   1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use llvm::{self, ValueRef, BasicBlockRef};
  12 use rustc::middle::lang_items;
  13 use rustc::ty::{self, Ty, TypeFoldable};
  14 use rustc::ty::layout::{self, LayoutOf};
  15 use rustc::mir;
  16 use abi::{Abi, ArgType, ArgTypeExt, FnType, FnTypeExt, LlvmType, PassMode};
  17 use base;
  18 use callee;
  19 use builder::Builder;
  20 use common::{self, C_bool, C_str_slice, C_struct, C_u32, C_uint_big, C_undef};
  21 use consts;
  22 use meth;
  23 use monomorphize;
  24 use type_of::LayoutLlvmExt;
  25 use type_::Type;
  26
  27 use syntax::symbol::Symbol;
  28 use syntax_pos::Pos;
  29
  30 use super::{FunctionCx, LocalRef};
  31 use super::place::PlaceRef;
  32 use super::operand::OperandRef;
  33 use super::operand::OperandValue::{Pair, Ref, Immediate};
  34
  35 impl<'a, 'tcx> FunctionCx<'a, 'tcx> {
  36     pub fn trans_block(&mut self, bb: mir::BasicBlock) {
  37         let mut bx = self.build_block(bb);
  38         let data = &self.mir[bb];
  39
  40         debug!("trans_block({:?}={:?})", bb, data);
  41
  42         for statement in &data.statements {
  43             bx = self.trans_statement(bx, statement);
  44         }
  45
  46         self.trans_terminator(bx, bb, data.terminator());
  47     }
  48
  49     fn trans_terminator(&mut self,
  50                         mut bx: Builder<'a, 'tcx>,
  51                         bb: mir::BasicBlock,
  52                         terminator: &mir::Terminator<'tcx>)
  53     {
  54         debug!("trans_terminator: {:?}", terminator);
  55
  56         // Create the cleanup bundle, if needed.
  57         let tcx = bx.tcx();
  58         let span = terminator.source_info.span;
  59         let funclet_bb = self.cleanup_kinds[bb].funclet_bb(bb);
  60         let funclet = funclet_bb.and_then(|funclet_bb| self.funclets[funclet_bb].as_ref());
  61
  62         let cleanup_pad = funclet.map(|lp| lp.cleanuppad());
  63         let cleanup_bundle = funclet.map(|l| l.bundle());
  64
  65         let lltarget = |this: &mut Self, target: mir::BasicBlock| {
  66             let lltarget = this.blocks[target];
  67             let target_funclet = this.cleanup_kinds[target].funclet_bb(target);
  68             match (funclet_bb, target_funclet) {
  69                 (None, None) => (lltarget, false),
  70                 (Some(f), Some(t_f))
  71                     if f == t_f || !base::wants_msvc_seh(tcx.sess)
  72                     => (lltarget, false),
  73                 (None, Some(_)) => {
  74                     // jump *into* cleanup - need a landing pad if GNU
  75                     (this.landing_pad_to(target), false)
  76                 }
  77                 (Some(_), None) => span_bug!(span, "{:?} - jump out of cleanup?", terminator),
  78                 (Some(_), Some(_)) => {
  79                     (this.landing_pad_to(target), true)
  80                 }
  81             }
  82         };
  83
  84         let llblock = |this: &mut Self, target: mir::BasicBlock| {
  85             let (lltarget, is_cleanupret) = lltarget(this, target);
  86             if is_cleanupret {
  87                 // MSVC cross-funclet jump - need a trampoline
  88
  89                 debug!("llblock: creating cleanup trampoline for {:?}", target);
  90                 let name = &format!("{:?}_cleanup_trampoline_{:?}", bb, target);
  91                 let trampoline = this.new_block(name);
  92                 trampoline.cleanup_ret(cleanup_pad.unwrap(), Some(lltarget));
  93                 trampoline.llbb()
  94             } else {
  95                 lltarget
  96             }
  97         };
  98
  99         let funclet_br = |this: &mut Self, bx: Builder, target: mir::BasicBlock| {
 100             let (lltarget, is_cleanupret) = lltarget(this, target);
 101             if is_cleanupret {
 102                 // micro-optimization: generate a `ret` rather than a jump
 103                 // to a trampoline.
 104                 bx.cleanup_ret(cleanup_pad.unwrap(), Some(lltarget));
 105             } else {
 106                 bx.br(lltarget);
 107             }
 108         };
 109
 110         let do_call = |
 111             this: &mut Self,
 112             bx: Builder<'a, 'tcx>,
 113             fn_ty: FnType<'tcx, Ty<'tcx>>,
 114             fn_ptr: ValueRef,
 115             llargs: &[ValueRef],
 116             destination: Option<(ReturnDest<'tcx>, mir::BasicBlock)>,
 117             cleanup: Option<mir::BasicBlock>
 118         | {
 119             if let Some(cleanup) = cleanup {
 120                 let ret_bx = if let Some((_, target)) = destination {
 121                     this.blocks[target]
 122                 } else {
 123                     this.unreachable_block()
 124                 };
 125                 let invokeret = bx.invoke(fn_ptr,
 126                                            &llargs,
 127                                            ret_bx,
 128                                            llblock(this, cleanup),
 129                                            cleanup_bundle);
 130                 fn_ty.apply_attrs_callsite(invokeret);
 131
 132                 if let Some((ret_dest, target)) = destination {
 133                     let ret_bx = this.build_block(target);
 134                     this.set_debug_loc(&ret_bx, terminator.source_info);
 135                     this.store_return(&ret_bx, ret_dest, &fn_ty.ret, invokeret);
 136                 }
 137             } else {
 138                 let llret = bx.call(fn_ptr, &llargs, cleanup_bundle);
 139                 fn_ty.apply_attrs_callsite(llret);
 140                 if this.mir[bb].is_cleanup {
 141                     // Cleanup is always the cold path. Don't inline
 142                     // drop glue. Also, when there is a deeply-nested
 143                     // struct, there are "symmetry" issues that cause
 144                     // exponential inlining - see issue #41696.
 145                     llvm::Attribute::NoInline.apply_callsite(llvm::AttributePlace::Function, llret);
 146                 }
 147
 148                 if let Some((ret_dest, target)) = destination {
 149                     this.store_return(&bx, ret_dest, &fn_ty.ret, llret);
 150                     funclet_br(this, bx, target);
 151                 } else {
 152                     bx.unreachable();
 153                 }
 154             }
 155         };
 156
 157         self.set_debug_loc(&bx, terminator.source_info);
 158         match terminator.kind {
 159             mir::TerminatorKind::Resume => {
 160                 if let Some(cleanup_pad) = cleanup_pad {
 161                     bx.cleanup_ret(cleanup_pad, None);
 162                 } else {
 163                     let slot = self.get_personality_slot(&bx);
 164                     let lp0 = slot.project_field(&bx, 0).load(&bx).immediate();
 165                     let lp1 = slot.project_field(&bx, 1).load(&bx).immediate();
 166                     slot.storage_dead(&bx);
 167
 168                     if !bx.sess().target.target.options.custom_unwind_resume {
 169                         let mut lp = C_undef(self.landing_pad_type());
 170                         lp = bx.insert_value(lp, lp0, 0);
 171                         lp = bx.insert_value(lp, lp1, 1);
 172                         bx.resume(lp);
 173                     } else {
 174                         bx.call(bx.cx.eh_unwind_resume(), &[lp0], cleanup_bundle);
 175                         bx.unreachable();
 176                     }
 177                 }
 178             }
 179
 180             mir::TerminatorKind::Abort => {
 181                 // Call core::intrinsics::abort()
 182                 let fnname = bx.cx.get_intrinsic(&("llvm.trap"));
 183                 bx.call(fnname, &[], None);
 184                 bx.unreachable();
 185             }
 186
 187             mir::TerminatorKind::Goto { target } => {
 188                 funclet_br(self, bx, target);
 189             }
 190
 191             mir::TerminatorKind::SwitchInt { ref discr, switch_ty, ref values, ref targets } => {
 192                 let discr = self.trans_operand(&bx, discr);
 193                 if switch_ty == bx.tcx().types.bool {
 194                     let lltrue = llblock(self, targets[0]);
 195                     let llfalse = llblock(self, targets[1]);
 196                     if let [0] = values[..] {
 197                         bx.cond_br(discr.immediate(), llfalse, lltrue);
 198                     } else {
 199                         assert_eq!(&values[..], &[1]);
 200                         bx.cond_br(discr.immediate(), lltrue, llfalse);
 201                     }
 202                 } else {
 203                     let (otherwise, targets) = targets.split_last().unwrap();
 204                     let switch = bx.switch(discr.immediate(),
 205                                             llblock(self, *otherwise), values.len());
 206                     let switch_llty = bx.cx.layout_of(switch_ty).immediate_llvm_type(bx.cx);
 207                     for (&value, target) in values.iter().zip(targets) {
 208                         let llval = C_uint_big(switch_llty, value);
 209                         let llbb = llblock(self, *target);
 210                         bx.add_case(switch, llval, llbb)
 211                     }
 212                 }
 213             }
 214
 215             mir::TerminatorKind::Return => {
 216                 let llval = match self.fn_ty.ret.mode {
 217                     PassMode::Ignore | PassMode::Indirect(_) => {
 218                         bx.ret_void();
 219                         return;
 220                     }
 221
 222                     PassMode::Direct(_) | PassMode::Pair(..) => {
 223                         let op = self.trans_consume(&bx, &mir::Place::Local(mir::RETURN_PLACE));
 224                         if let Ref(llval, align) = op.val {
 225                             bx.load(llval, align)
 226                         } else {
 227                             op.immediate_or_packed_pair(&bx)
 228                         }
 229                     }
 230
 231                     PassMode::Cast(cast_ty) => {
 232                         let op = match self.locals[mir::RETURN_PLACE] {
 233                             LocalRef::Operand(Some(op)) => op,
 234                             LocalRef::Operand(None) => bug!("use of return before def"),
 235                             LocalRef::Place(tr_place) => {
 236                                 OperandRef {
 237                                     val: Ref(tr_place.llval, tr_place.align),
 238                                     layout: tr_place.layout
 239                                 }
 240                             }
 241                         };
 242                         let llslot = match op.val {
 243                             Immediate(_) | Pair(..) => {
 244                                 let scratch = PlaceRef::alloca(&bx, self.fn_ty.ret.layout, "ret");
 245                                 op.val.store(&bx, scratch);
 246                                 scratch.llval
 247                             }
 248                             Ref(llval, align) => {
 249                                 assert_eq!(align.abi(), op.layout.align.abi(),
 250                                            "return place is unaligned!");
 251                                 llval
 252                             }
 253                         };
 254                         bx.load(
 255                             bx.pointercast(llslot, cast_ty.llvm_type(bx.cx).ptr_to()),
 256                             self.fn_ty.ret.layout.align)
 257                     }
 258                 };
 259                 bx.ret(llval);
 260             }
 261
 262             mir::TerminatorKind::Unreachable => {
 263                 bx.unreachable();
 264             }
 265
 266             mir::TerminatorKind::Drop { ref location, target, unwind } => {
 267                 let ty = location.ty(self.mir, bx.tcx()).to_ty(bx.tcx());
 268                 let ty = self.monomorphize(&ty);
 269                 let drop_fn = monomorphize::resolve_drop_in_place(bx.cx.tcx, ty);
 270
 271                 if let ty::InstanceDef::DropGlue(_, None) = drop_fn.def {
 272                     // we don't actually need to drop anything.
 273                     funclet_br(self, bx, target);
 274                     return
 275                 }
 276
 277                 let place = self.trans_place(&bx, location);
 278                 let mut args: &[_] = &[place.llval, place.llextra];
 279                 args = &args[..1 + place.has_extra() as usize];
 280                 let (drop_fn, fn_ty) = match ty.sty {
 281                     ty::TyDynamic(..) => {
 282                         let fn_ty = drop_fn.ty(bx.cx.tcx);
 283                         let sig = common::ty_fn_sig(bx.cx, fn_ty);
 284                         let sig = bx.tcx().normalize_erasing_late_bound_regions(
 285                             ty::ParamEnv::reveal_all(),
 286                             &sig,
 287                         );
 288                         let fn_ty = FnType::new_vtable(bx.cx, sig, &[]);
 289                         args = &args[..1];
 290                         (meth::DESTRUCTOR.get_fn(&bx, place.llextra, &fn_ty), fn_ty)
 291                     }
 292                     _ => {
 293                         (callee::get_fn(bx.cx, drop_fn),
 294                          FnType::of_instance(bx.cx, &drop_fn))
 295                     }
 296                 };
 297                 do_call(self, bx, fn_ty, drop_fn, args,
 298                         Some((ReturnDest::Nothing, target)),
 299                         unwind);
 300             }
 301
 302             mir::TerminatorKind::Assert { ref cond, expected, ref msg, target, cleanup } => {
 303                 let cond = self.trans_operand(&bx, cond).immediate();
 304                 let mut const_cond = common::const_to_opt_u128(cond, false).map(|c| c == 1);
 305
 306                 // This case can currently arise only from functions marked
 307                 // with #[rustc_inherit_overflow_checks] and inlined from
 308                 // another crate (mostly core::num generic/#[inline] fns),
 309                 // while the current crate doesn't use overflow checks.
 310                 // NOTE: Unlike binops, negation doesn't have its own
 311                 // checked operation, just a comparison with the minimum
 312                 // value, so we have to check for the assert message.
 313                 if !bx.cx.check_overflow {
 314                     use rustc_const_math::ConstMathErr::Overflow;
 315                     use rustc_const_math::Op::Neg;
 316
 317                     if let mir::AssertMessage::Math(Overflow(Neg)) = *msg {
 318                         const_cond = Some(expected);
 319                     }
 320                 }
 321
 322                 // Don't translate the panic block if success if known.
 323                 if const_cond == Some(expected) {
 324                     funclet_br(self, bx, target);
 325                     return;
 326                 }
 327
 328                 // Pass the condition through llvm.expect for branch hinting.
 329                 let expect = bx.cx.get_intrinsic(&"llvm.expect.i1");
 330                 let cond = bx.call(expect, &[cond, C_bool(bx.cx, expected)], None);
 331
 332                 // Create the failure block and the conditional branch to it.
 333                 let lltarget = llblock(self, target);
 334                 let panic_block = self.new_block("panic");
 335                 if expected {
 336                     bx.cond_br(cond, lltarget, panic_block.llbb());
 337                 } else {
 338                     bx.cond_br(cond, panic_block.llbb(), lltarget);
 339                 }
 340
 341                 // After this point, bx is the block for the call to panic.
 342                 bx = panic_block;
 343                 self.set_debug_loc(&bx, terminator.source_info);
 344
 345                 // Get the location information.
 346                 let loc = bx.sess().codemap().lookup_char_pos(span.lo());
 347                 let filename = Symbol::intern(&loc.file.name.to_string()).as_str();
 348                 let filename = C_str_slice(bx.cx, filename);
 349                 let line = C_u32(bx.cx, loc.line as u32);
 350                 let col = C_u32(bx.cx, loc.col.to_usize() as u32 + 1);
 351                 let align = tcx.data_layout.aggregate_align
 352                     .max(tcx.data_layout.i32_align)
 353                     .max(tcx.data_layout.pointer_align);
 354
 355                 // Put together the arguments to the panic entry point.
 356                 let (lang_item, args) = match *msg {
 357                     mir::AssertMessage::BoundsCheck { ref len, ref index } => {
 358                         let len = self.trans_operand(&mut bx, len).immediate();
 359                         let index = self.trans_operand(&mut bx, index).immediate();
 360
 361                         let file_line_col = C_struct(bx.cx, &[filename, line, col], false);
 362                         let file_line_col = consts::addr_of(bx.cx,
 363                                                             file_line_col,
 364                                                             align,
 365                                                             "panic_bounds_check_loc");
 366                         (lang_items::PanicBoundsCheckFnLangItem,
 367                          vec![file_line_col, index, len])
 368                     }
 369                     mir::AssertMessage::Math(ref err) => {
 370                         let msg_str = Symbol::intern(err.description()).as_str();
 371                         let msg_str = C_str_slice(bx.cx, msg_str);
 372                         let msg_file_line_col = C_struct(bx.cx,
 373                                                      &[msg_str, filename, line, col],
 374                                                      false);
 375                         let msg_file_line_col = consts::addr_of(bx.cx,
 376                                                                 msg_file_line_col,
 377                                                                 align,
 378                                                                 "panic_loc");
 379                         (lang_items::PanicFnLangItem,
 380                          vec![msg_file_line_col])
 381                     }
 382                     mir::AssertMessage::GeneratorResumedAfterReturn |
 383                     mir::AssertMessage::GeneratorResumedAfterPanic => {
 384                         let str = if let mir::AssertMessage::GeneratorResumedAfterReturn = *msg {
 385                             "generator resumed after completion"
 386                         } else {
 387                             "generator resumed after panicking"
 388                         };
 389                         let msg_str = Symbol::intern(str).as_str();
 390                         let msg_str = C_str_slice(bx.cx, msg_str);
 391                         let msg_file_line_col = C_struct(bx.cx,
 392                                                      &[msg_str, filename, line, col],
 393                                                      false);
 394                         let msg_file_line_col = consts::addr_of(bx.cx,
 395                                                                 msg_file_line_col,
 396                                                                 align,
 397                                                                 "panic_loc");
 398                         (lang_items::PanicFnLangItem,
 399                          vec![msg_file_line_col])
 400                     }
 401                 };
 402
 403                 // Obtain the panic entry point.
 404                 let def_id = common::langcall(bx.tcx(), Some(span), "", lang_item);
 405                 let instance = ty::Instance::mono(bx.tcx(), def_id);
 406                 let fn_ty = FnType::of_instance(bx.cx, &instance);
 407                 let llfn = callee::get_fn(bx.cx, instance);
 408
 409                 // Translate the actual panic invoke/call.
 410                 do_call(self, bx, fn_ty, llfn, &args, None, cleanup);
 411             }
 412
 413             mir::TerminatorKind::DropAndReplace { .. } => {
 414                 bug!("undesugared DropAndReplace in trans: {:?}", terminator);
 415             }
 416
 417             mir::TerminatorKind::Call { ref func, ref args, ref destination, cleanup } => {
 418                 // Create the callee. This is a fn ptr or zero-sized and hence a kind of scalar.
 419                 let callee = self.trans_operand(&bx, func);
 420
 421                 let (instance, mut llfn) = match callee.layout.ty.sty {
 422                     ty::TyFnDef(def_id, substs) => {
 423                         (Some(ty::Instance::resolve(bx.cx.tcx,
 424                                                     ty::ParamEnv::reveal_all(),
 425                                                     def_id,
 426                                                     substs).unwrap()),
 427                          None)
 428                     }
 429                     ty::TyFnPtr(_) => {
 430                         (None, Some(callee.immediate()))
 431                     }
 432                     _ => bug!("{} is not callable", callee.layout.ty)
 433                 };
 434                 let def = instance.map(|i| i.def);
 435                 let sig = callee.layout.ty.fn_sig(bx.tcx());
 436                 let sig = bx.tcx().normalize_erasing_late_bound_regions(
 437                     ty::ParamEnv::reveal_all(),
 438                     &sig,
 439                 );
 440                 let abi = sig.abi;
 441
 442                 // Handle intrinsics old trans wants Expr's for, ourselves.
 443                 let intrinsic = match def {
 444                     Some(ty::InstanceDef::Intrinsic(def_id))
 445                         => Some(bx.tcx().item_name(def_id)),
 446                     _ => None
 447                 };
 448                 let intrinsic = intrinsic.as_ref().map(|s| &s[..]);
 449
 450                 if intrinsic == Some("transmute") {
 451                     let &(ref dest, target) = destination.as_ref().unwrap();
 452                     self.trans_transmute(&bx, &args[0], dest);
 453                     funclet_br(self, bx, target);
 454                     return;
 455                 }
 456
 457                 let extra_args = &args[sig.inputs().len()..];
 458                 let extra_args = extra_args.iter().map(|op_arg| {
 459                     let op_ty = op_arg.ty(self.mir, bx.tcx());
 460                     self.monomorphize(&op_ty)
 461                 }).collect::<Vec<_>>();
 462
 463                 let fn_ty = match def {
 464                     Some(ty::InstanceDef::Virtual(..)) => {
 465                         FnType::new_vtable(bx.cx, sig, &extra_args)
 466                     }
 467                     Some(ty::InstanceDef::DropGlue(_, None)) => {
 468                         // empty drop glue - a nop.
 469                         let &(_, target) = destination.as_ref().unwrap();
 470                         funclet_br(self, bx, target);
 471                         return;
 472                     }
 473                     _ => FnType::new(bx.cx, sig, &extra_args)
 474                 };
 475
 476                 // The arguments we'll be passing. Plus one to account for outptr, if used.
 477                 let arg_count = fn_ty.args.len() + fn_ty.ret.is_indirect() as usize;
 478                 let mut llargs = Vec::with_capacity(arg_count);
 479
 480                 // Prepare the return value destination
 481                 let ret_dest = if let Some((ref dest, _)) = *destination {
 482                     let is_intrinsic = intrinsic.is_some();
 483                     self.make_return_dest(&bx, dest, &fn_ty.ret, &mut llargs,
 484                                           is_intrinsic)
 485                 } else {
 486                     ReturnDest::Nothing
 487                 };
 488
 489                 if intrinsic.is_some() && intrinsic != Some("drop_in_place") {
 490                     use intrinsic::trans_intrinsic_call;
 491
 492                     let dest = match ret_dest {
 493                         _ if fn_ty.ret.is_indirect() => llargs[0],
 494                         ReturnDest::Nothing => {
 495                             C_undef(fn_ty.ret.memory_ty(bx.cx).ptr_to())
 496                         }
 497                         ReturnDest::IndirectOperand(dst, _) |
 498                         ReturnDest::Store(dst) => dst.llval,
 499                         ReturnDest::DirectOperand(_) =>
 500                             bug!("Cannot use direct operand with an intrinsic call")
 501                     };
 502
 503                     let args: Vec<_> = args.iter().enumerate().map(|(i, arg)| {
 504                         // The indices passed to simd_shuffle* in the
 505                         // third argument must be constant. This is
 506                         // checked by const-qualification, which also
 507                         // promotes any complex rvalues to constants.
 508                         if i == 2 && intrinsic.unwrap().starts_with("simd_shuffle") {
 509                             match *arg {
 510                                 mir::Operand::Copy(_) |
 511                                 mir::Operand::Move(_) => {
 512                                     span_bug!(span, "shuffle indices must be constant");
 513                                 }
 514                                 mir::Operand::Constant(ref constant) => {
 515                                     let (llval, ty) = self.simd_shuffle_indices(
 516                                         &bx,
 517                                         constant,
 518                                     );
 519                                     return OperandRef {
 520                                         val: Immediate(llval),
 521                                         layout: bx.cx.layout_of(ty)
 522                                     };
 523                                 }
 524                             }
 525                         }
 526
 527                         self.trans_operand(&bx, arg)
 528                     }).collect();
 529
 530
 531                     let callee_ty = instance.as_ref().unwrap().ty(bx.cx.tcx);
 532                     trans_intrinsic_call(&bx, callee_ty, &fn_ty, &args, dest,
 533                                          terminator.source_info.span);
 534
 535                     if let ReturnDest::IndirectOperand(dst, _) = ret_dest {
 536                         self.store_return(&bx, ret_dest, &fn_ty.ret, dst.llval);
 537                     }
 538
 539                     if let Some((_, target)) = *destination {
 540                         funclet_br(self, bx, target);
 541                     } else {
 542                         bx.unreachable();
 543                     }
 544
 545                     return;
 546                 }
 547
 548                 // Split the rust-call tupled arguments off.
 549                 let (first_args, untuple) = if abi == Abi::RustCall && !args.is_empty() {
 550                     let (tup, args) = args.split_last().unwrap();
 551                     (args, Some(tup))
 552                 } else {
 553                     (&args[..], None)
 554                 };
 555
 556                 for (i, arg) in first_args.iter().enumerate() {
 557                     let mut op = self.trans_operand(&bx, arg);
 558                     if let (0, Some(ty::InstanceDef::Virtual(_, idx))) = (i, def) {
 559                         if let Pair(data_ptr, meta) = op.val {
 560                             llfn = Some(meth::VirtualIndex::from_index(idx)
 561                                 .get_fn(&bx, meta, &fn_ty));
 562                             llargs.push(data_ptr);
 563                             continue;
 564                         }
 565                     }
 566
 567                     // The callee needs to own the argument memory if we pass it
 568                     // by-ref, so make a local copy of non-immediate constants.
 569                     match (arg, op.val) {
 570                         (&mir::Operand::Copy(_), Ref(..)) |
 571                         (&mir::Operand::Constant(_), Ref(..)) => {
 572                             let tmp = PlaceRef::alloca(&bx, op.layout, "const");
 573                             op.val.store(&bx, tmp);
 574                             op.val = Ref(tmp.llval, tmp.align);
 575                         }
 576                         _ => {}
 577                     }
 578
 579                     self.trans_argument(&bx, op, &mut llargs, &fn_ty.args[i]);
 580                 }
 581                 if let Some(tup) = untuple {
 582                     self.trans_arguments_untupled(&bx, tup, &mut llargs,
 583                         &fn_ty.args[first_args.len()..])
 584                 }
 585
 586                 let fn_ptr = match (llfn, instance) {
 587                     (Some(llfn), _) => llfn,
 588                     (None, Some(instance)) => callee::get_fn(bx.cx, instance),
 589                     _ => span_bug!(span, "no llfn for call"),
 590                 };
 591
 592                 do_call(self, bx, fn_ty, fn_ptr, &llargs,
 593                         destination.as_ref().map(|&(_, target)| (ret_dest, target)),
 594                         cleanup);
 595             }
 596             mir::TerminatorKind::GeneratorDrop |
 597             mir::TerminatorKind::Yield { .. } => bug!("generator ops in trans"),
 598             mir::TerminatorKind::FalseEdges { .. } |
 599             mir::TerminatorKind::FalseUnwind { .. } => bug!("borrowck false edges in trans"),
 600         }
 601     }
 602
 603     fn trans_argument(&mut self,
 604                       bx: &Builder<'a, 'tcx>,
 605                       op: OperandRef<'tcx>,
 606                       llargs: &mut Vec<ValueRef>,
 607                       arg: &ArgType<'tcx, Ty<'tcx>>) {
 608         // Fill padding with undef value, where applicable.
 609         if let Some(ty) = arg.pad {
 610             llargs.push(C_undef(ty.llvm_type(bx.cx)));
 611         }
 612
 613         if arg.is_ignore() {
 614             return;
 615         }
 616
 617         if let PassMode::Pair(..) = arg.mode {
 618             match op.val {
 619                 Pair(a, b) => {
 620                     llargs.push(a);
 621                     llargs.push(b);
 622                     return;
 623                 }
 624                 _ => bug!("trans_argument: {:?} invalid for pair arugment", op)
 625             }
 626         }
 627
 628         // Force by-ref if we have to load through a cast pointer.
 629         let (mut llval, align, by_ref) = match op.val {
 630             Immediate(_) | Pair(..) => {
 631                 match arg.mode {
 632                     PassMode::Indirect(_) | PassMode::Cast(_) => {
 633                         let scratch = PlaceRef::alloca(bx, arg.layout, "arg");
 634                         op.val.store(bx, scratch);
 635                         (scratch.llval, scratch.align, true)
 636                     }
 637                     _ => {
 638                         (op.immediate_or_packed_pair(bx), arg.layout.align, false)
 639                     }
 640                 }
 641             }
 642             Ref(llval, align) => {
 643                 if arg.is_indirect() && align.abi() < arg.layout.align.abi() {
 644                     // `foo(packed.large_field)`. We can't pass the (unaligned) field directly. I
 645                     // think that ATM (Rust 1.16) we only pass temporaries, but we shouldn't
 646                     // have scary latent bugs around.
 647
 648                     let scratch = PlaceRef::alloca(bx, arg.layout, "arg");
 649                     base::memcpy_ty(bx, scratch.llval, llval, op.layout, align);
 650                     (scratch.llval, scratch.align, true)
 651                 } else {
 652                     (llval, align, true)
 653                 }
 654             }
 655         };
 656
 657         if by_ref && !arg.is_indirect() {
 658             // Have to load the argument, maybe while casting it.
 659             if let PassMode::Cast(ty) = arg.mode {
 660                 llval = bx.load(bx.pointercast(llval, ty.llvm_type(bx.cx).ptr_to()),
 661                                  align.min(arg.layout.align));
 662             } else {
 663                 // We can't use `PlaceRef::load` here because the argument
 664                 // may have a type we don't treat as immediate, but the ABI
 665                 // used for this call is passing it by-value. In that case,
 666                 // the load would just produce `OperandValue::Ref` instead
 667                 // of the `OperandValue::Immediate` we need for the call.
 668                 llval = bx.load(llval, align);
 669                 if let layout::Abi::Scalar(ref scalar) = arg.layout.abi {
 670                     if scalar.is_bool() {
 671                         bx.range_metadata(llval, 0..2);
 672                     }
 673                 }
 674                 // We store bools as i8 so we need to truncate to i1.
 675                 llval = base::to_immediate(bx, llval, arg.layout);
 676             }
 677         }
 678
 679         llargs.push(llval);
 680     }
 681
 682     fn trans_arguments_untupled(&mut self,
 683                                 bx: &Builder<'a, 'tcx>,
 684                                 operand: &mir::Operand<'tcx>,
 685                                 llargs: &mut Vec<ValueRef>,
 686                                 args: &[ArgType<'tcx, Ty<'tcx>>]) {
 687         let tuple = self.trans_operand(bx, operand);
 688
 689         // Handle both by-ref and immediate tuples.
 690         if let Ref(llval, align) = tuple.val {
 691             let tuple_ptr = PlaceRef::new_sized(llval, tuple.layout, align);
 692             for i in 0..tuple.layout.fields.count() {
 693                 let field_ptr = tuple_ptr.project_field(bx, i);
 694                 self.trans_argument(bx, field_ptr.load(bx), llargs, &args[i]);
 695             }
 696         } else {
 697             // If the tuple is immediate, the elements are as well.
 698             for i in 0..tuple.layout.fields.count() {
 699                 let op = tuple.extract_field(bx, i);
 700                 self.trans_argument(bx, op, llargs, &args[i]);
 701             }
 702         }
 703     }
 704
 705     fn get_personality_slot(&mut self, bx: &Builder<'a, 'tcx>) -> PlaceRef<'tcx> {
 706         let cx = bx.cx;
 707         if let Some(slot) = self.personality_slot {
 708             slot
 709         } else {
 710             let layout = cx.layout_of(cx.tcx.intern_tup(&[
 711                 cx.tcx.mk_mut_ptr(cx.tcx.types.u8),
 712                 cx.tcx.types.i32
 713             ]));
 714             let slot = PlaceRef::alloca(bx, layout, "personalityslot");
 715             self.personality_slot = Some(slot);
 716             slot
 717         }
 718     }
 719
 720     /// Return the landingpad wrapper around the given basic block
 721     ///
 722     /// No-op in MSVC SEH scheme.
 723     fn landing_pad_to(&mut self, target_bb: mir::BasicBlock) -> BasicBlockRef {
 724         if let Some(block) = self.landing_pads[target_bb] {
 725             return block;
 726         }
 727
 728         let block = self.blocks[target_bb];
 729         let landing_pad = self.landing_pad_uncached(block);
 730         self.landing_pads[target_bb] = Some(landing_pad);
 731         landing_pad
 732     }
 733
 734     fn landing_pad_uncached(&mut self, target_bb: BasicBlockRef) -> BasicBlockRef {
 735         if base::wants_msvc_seh(self.cx.sess()) {
 736             span_bug!(self.mir.span, "landing pad was not inserted?")
 737         }
 738
 739         let bx = self.new_block("cleanup");
 740
 741         let llpersonality = self.cx.eh_personality();
 742         let llretty = self.landing_pad_type();
 743         let lp = bx.landing_pad(llretty, llpersonality, 1);
 744         bx.set_cleanup(lp);
 745
 746         let slot = self.get_personality_slot(&bx);
 747         slot.storage_live(&bx);
 748         Pair(bx.extract_value(lp, 0), bx.extract_value(lp, 1)).store(&bx, slot);
 749
 750         bx.br(target_bb);
 751         bx.llbb()
 752     }
 753
 754     fn landing_pad_type(&self) -> Type {
 755         let cx = self.cx;
 756         Type::struct_(cx, &[Type::i8p(cx), Type::i32(cx)], false)
 757     }
 758
 759     fn unreachable_block(&mut self) -> BasicBlockRef {
 760         self.unreachable_block.unwrap_or_else(|| {
 761             let bl = self.new_block("unreachable");
 762             bl.unreachable();
 763             self.unreachable_block = Some(bl.llbb());
 764             bl.llbb()
 765         })
 766     }
 767
 768     pub fn new_block(&self, name: &str) -> Builder<'a, 'tcx> {
 769         Builder::new_block(self.cx, self.llfn, name)
 770     }
 771
 772     pub fn build_block(&self, bb: mir::BasicBlock) -> Builder<'a, 'tcx> {
 773         let bx = Builder::with_cx(self.cx);
 774         bx.position_at_end(self.blocks[bb]);
 775         bx
 776     }
 777
 778     fn make_return_dest(&mut self, bx: &Builder<'a, 'tcx>,
 779                         dest: &mir::Place<'tcx>, fn_ret: &ArgType<'tcx, Ty<'tcx>>,
 780                         llargs: &mut Vec<ValueRef>, is_intrinsic: bool)
 781                         -> ReturnDest<'tcx> {
 782         // If the return is ignored, we can just return a do-nothing ReturnDest
 783         if fn_ret.is_ignore() {
 784             return ReturnDest::Nothing;
 785         }
 786         let dest = if let mir::Place::Local(index) = *dest {
 787             match self.locals[index] {
 788                 LocalRef::Place(dest) => dest,
 789                 LocalRef::Operand(None) => {
 790                     // Handle temporary places, specifically Operand ones, as
 791                     // they don't have allocas
 792                     return if fn_ret.is_indirect() {
 793                         // Odd, but possible, case, we have an operand temporary,
 794                         // but the calling convention has an indirect return.
 795                         let tmp = PlaceRef::alloca(bx, fn_ret.layout, "tmp_ret");
 796                         tmp.storage_live(bx);
 797                         llargs.push(tmp.llval);
 798                         ReturnDest::IndirectOperand(tmp, index)
 799                     } else if is_intrinsic {
 800                         // Currently, intrinsics always need a location to store
 801                         // the result. so we create a temporary alloca for the
 802                         // result
 803                         let tmp = PlaceRef::alloca(bx, fn_ret.layout, "tmp_ret");
 804                         tmp.storage_live(bx);
 805                         ReturnDest::IndirectOperand(tmp, index)
 806                     } else {
 807                         ReturnDest::DirectOperand(index)
 808                     };
 809                 }
 810                 LocalRef::Operand(Some(_)) => {
 811                     bug!("place local already assigned to");
 812                 }
 813             }
 814         } else {
 815             self.trans_place(bx, dest)
 816         };
 817         if fn_ret.is_indirect() {
 818             if dest.align.abi() < dest.layout.align.abi() {
 819                 // Currently, MIR code generation does not create calls
 820                 // that store directly to fields of packed structs (in
 821                 // fact, the calls it creates write only to temps),
 822                 //
 823                 // If someone changes that, please update this code path
 824                 // to create a temporary.
 825                 span_bug!(self.mir.span, "can't directly store to unaligned value");
 826             }
 827             llargs.push(dest.llval);
 828             ReturnDest::Nothing
 829         } else {
 830             ReturnDest::Store(dest)
 831         }
 832     }
 833
 834     fn trans_transmute(&mut self, bx: &Builder<'a, 'tcx>,
 835                        src: &mir::Operand<'tcx>,
 836                        dst: &mir::Place<'tcx>) {
 837         if let mir::Place::Local(index) = *dst {
 838             match self.locals[index] {
 839                 LocalRef::Place(place) => self.trans_transmute_into(bx, src, place),
 840                 LocalRef::Operand(None) => {
 841                     let dst_layout = bx.cx.layout_of(self.monomorphized_place_ty(dst));
 842                     assert!(!dst_layout.ty.has_erasable_regions());
 843                     let place = PlaceRef::alloca(bx, dst_layout, "transmute_temp");
 844                     place.storage_live(bx);
 845                     self.trans_transmute_into(bx, src, place);
 846                     let op = place.load(bx);
 847                     place.storage_dead(bx);
 848                     self.locals[index] = LocalRef::Operand(Some(op));
 849                 }
 850                 LocalRef::Operand(Some(op)) => {
 851                     assert!(op.layout.is_zst(),
 852                             "assigning to initialized SSAtemp");
 853                 }
 854             }
 855         } else {
 856             let dst = self.trans_place(bx, dst);
 857             self.trans_transmute_into(bx, src, dst);
 858         }
 859     }
 860
 861     fn trans_transmute_into(&mut self, bx: &Builder<'a, 'tcx>,
 862                             src: &mir::Operand<'tcx>,
 863                             dst: PlaceRef<'tcx>) {
 864         let src = self.trans_operand(bx, src);
 865         let llty = src.layout.llvm_type(bx.cx);
 866         let cast_ptr = bx.pointercast(dst.llval, llty.ptr_to());
 867         let align = src.layout.align.min(dst.layout.align);
 868         src.val.store(bx, PlaceRef::new_sized(cast_ptr, src.layout, align));
 869     }
 870
 871
 872     // Stores the return value of a function call into it's final location.
 873     fn store_return(&mut self,
 874                     bx: &Builder<'a, 'tcx>,
 875                     dest: ReturnDest<'tcx>,
 876                     ret_ty: &ArgType<'tcx, Ty<'tcx>>,
 877                     llval: ValueRef) {
 878         use self::ReturnDest::*;
 879
 880         match dest {
 881             Nothing => (),
 882             Store(dst) => ret_ty.store(bx, llval, dst),
 883             IndirectOperand(tmp, index) => {
 884                 let op = tmp.load(bx);
 885                 tmp.storage_dead(bx);
 886                 self.locals[index] = LocalRef::Operand(Some(op));
 887             }
 888             DirectOperand(index) => {
 889                 // If there is a cast, we have to store and reload.
 890                 let op = if let PassMode::Cast(_) = ret_ty.mode {
 891                     let tmp = PlaceRef::alloca(bx, ret_ty.layout, "tmp_ret");
 892                     tmp.storage_live(bx);
 893                     ret_ty.store(bx, llval, tmp);
 894                     let op = tmp.load(bx);
 895                     tmp.storage_dead(bx);
 896                     op
 897                 } else {
 898                     OperandRef::from_immediate_or_packed_pair(bx, llval, ret_ty.layout)
 899                 };
 900                 self.locals[index] = LocalRef::Operand(Some(op));
 901             }
 902         }
 903     }
 904 }
 905
 906 enum ReturnDest<'tcx> {
 907     // Do nothing, the return value is indirect or ignored
 908     Nothing,
 909     // Store the return value to the pointer
 910     Store(PlaceRef<'tcx>),
 911     // Stores an indirect return value to an operand local place
 912     IndirectOperand(PlaceRef<'tcx>, mir::Local),
 913     // Stores a direct return value to an operand local place
 914     DirectOperand(mir::Local)
 915 }