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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 #![allow(non_upper_case_globals)]
12
13 use intrinsics::{self, Intrinsic};
14 use libc;
15 use llvm;
16 use llvm::{ValueRef};
17 use abi::{Abi, FnType};
18 use adt;
19 use mir::lvalue::LvalueRef;
20 use base::*;
21 use common::*;
22 use declare;
23 use glue;
24 use type_of;
25 use machine;
26 use type_::Type;
27 use rustc::ty::{self, Ty};
28 use rustc::hir;
29 use syntax::ast;
30 use syntax::symbol::Symbol;
31 use builder::Builder;
32
33 use rustc::session::Session;
34 use syntax_pos::Span;
35
36 use std::cmp::Ordering;
37 use std::iter;
38
39 use mir::lvalue::Alignment;
40
41 fn get_simple_intrinsic(ccx: &CrateContext, name: &str) -> Option<ValueRef> {
42     let llvm_name = match name {
43         "sqrtf32" => "llvm.sqrt.f32",
44         "sqrtf64" => "llvm.sqrt.f64",
45         "powif32" => "llvm.powi.f32",
46         "powif64" => "llvm.powi.f64",
47         "sinf32" => "llvm.sin.f32",
48         "sinf64" => "llvm.sin.f64",
49         "cosf32" => "llvm.cos.f32",
50         "cosf64" => "llvm.cos.f64",
51         "powf32" => "llvm.pow.f32",
52         "powf64" => "llvm.pow.f64",
53         "expf32" => "llvm.exp.f32",
54         "expf64" => "llvm.exp.f64",
55         "exp2f32" => "llvm.exp2.f32",
56         "exp2f64" => "llvm.exp2.f64",
57         "logf32" => "llvm.log.f32",
58         "logf64" => "llvm.log.f64",
59         "log10f32" => "llvm.log10.f32",
60         "log10f64" => "llvm.log10.f64",
61         "log2f32" => "llvm.log2.f32",
62         "log2f64" => "llvm.log2.f64",
63         "fmaf32" => "llvm.fma.f32",
64         "fmaf64" => "llvm.fma.f64",
65         "fabsf32" => "llvm.fabs.f32",
66         "fabsf64" => "llvm.fabs.f64",
67         "copysignf32" => "llvm.copysign.f32",
68         "copysignf64" => "llvm.copysign.f64",
69         "floorf32" => "llvm.floor.f32",
70         "floorf64" => "llvm.floor.f64",
71         "ceilf32" => "llvm.ceil.f32",
72         "ceilf64" => "llvm.ceil.f64",
73         "truncf32" => "llvm.trunc.f32",
74         "truncf64" => "llvm.trunc.f64",
75         "rintf32" => "llvm.rint.f32",
76         "rintf64" => "llvm.rint.f64",
77         "nearbyintf32" => "llvm.nearbyint.f32",
78         "nearbyintf64" => "llvm.nearbyint.f64",
79         "roundf32" => "llvm.round.f32",
80         "roundf64" => "llvm.round.f64",
81         "assume" => "llvm.assume",
82         "abort" => "llvm.trap",
83         _ => return None
84     };
85     Some(ccx.get_intrinsic(&llvm_name))
86 }
87
88 /// Remember to add all intrinsics here, in librustc_typeck/check/mod.rs,
89 /// and in libcore/intrinsics.rs; if you need access to any llvm intrinsics,
90 /// add them to librustc_trans/trans/context.rs
91 pub fn trans_intrinsic_call<'a, 'tcx>(bcx: &Builder<'a, 'tcx>,
92                                       callee_ty: Ty<'tcx>,
93                                       fn_ty: &FnType,
94                                       llargs: &[ValueRef],
95                                       llresult: ValueRef,
96                                       span: Span) {
97     let ccx = bcx.ccx;
98     let tcx = ccx.tcx();
99
100     let (def_id, substs, sig) = match callee_ty.sty {
101         ty::TyFnDef(def_id, substs, sig) => (def_id, substs, sig),
102         _ => bug!("expected fn item type, found {}", callee_ty)
103     };
104
105     let sig = tcx.erase_late_bound_regions_and_normalize(&sig);
106     let arg_tys = sig.inputs();
107     let ret_ty = sig.output();
108     let name = &*tcx.item_name(def_id).as_str();
109
110     let llret_ty = type_of::type_of(ccx, ret_ty);
111
112     let simple = get_simple_intrinsic(ccx, name);
113     let llval = match name {
114         _ if simple.is_some() => {
115             bcx.call(simple.unwrap(), &llargs, None)
116         }
117         "unreachable" => {
118             return;
119         },
120         "likely" => {
121             let expect = ccx.get_intrinsic(&("llvm.expect.i1"));
122             bcx.call(expect, &[llargs[0], C_bool(ccx, true)], None)
123         }
124         "unlikely" => {
125             let expect = ccx.get_intrinsic(&("llvm.expect.i1"));
126             bcx.call(expect, &[llargs[0], C_bool(ccx, false)], None)
127         }
128         "try" => {
129             try_intrinsic(bcx, ccx, llargs[0], llargs[1], llargs[2], llresult);
130             C_nil(ccx)
131         }
132         "breakpoint" => {
133             let llfn = ccx.get_intrinsic(&("llvm.debugtrap"));
134             bcx.call(llfn, &[], None)
135         }
136         "size_of" => {
137             let tp_ty = substs.type_at(0);
138             let lltp_ty = type_of::type_of(ccx, tp_ty);
139             C_uint(ccx, machine::llsize_of_alloc(ccx, lltp_ty))
140         }
141         "size_of_val" => {
142             let tp_ty = substs.type_at(0);
143             if !bcx.ccx.shared().type_is_sized(tp_ty) {
144                 let (llsize, _) =
145                     glue::size_and_align_of_dst(bcx, tp_ty, llargs[1]);
146                 llsize
147             } else {
148                 let lltp_ty = type_of::type_of(ccx, tp_ty);
149                 C_uint(ccx, machine::llsize_of_alloc(ccx, lltp_ty))
150             }
151         }
152         "min_align_of" => {
153             let tp_ty = substs.type_at(0);
154             C_uint(ccx, type_of::align_of(ccx, tp_ty))
155         }
156         "min_align_of_val" => {
157             let tp_ty = substs.type_at(0);
158             if !bcx.ccx.shared().type_is_sized(tp_ty) {
159                 let (_, llalign) =
160                     glue::size_and_align_of_dst(bcx, tp_ty, llargs[1]);
161                 llalign
162             } else {
163                 C_uint(ccx, type_of::align_of(ccx, tp_ty))
164             }
165         }
166         "pref_align_of" => {
167             let tp_ty = substs.type_at(0);
168             let lltp_ty = type_of::type_of(ccx, tp_ty);
169             C_uint(ccx, machine::llalign_of_pref(ccx, lltp_ty))
170         }
171         "type_name" => {
172             let tp_ty = substs.type_at(0);
173             let ty_name = Symbol::intern(&tp_ty.to_string()).as_str();
174             C_str_slice(ccx, ty_name)
175         }
176         "type_id" => {
177             C_u64(ccx, ccx.tcx().type_id_hash(substs.type_at(0)))
178         }
179         "init" => {
180             let ty = substs.type_at(0);
181             if !type_is_zero_size(ccx, ty) {
182                 // Just zero out the stack slot.
183                 // If we store a zero constant, LLVM will drown in vreg allocation for large data
184                 // structures, and the generated code will be awful. (A telltale sign of this is
185                 // large quantities of `mov [byte ptr foo],0` in the generated code.)
186                 memset_intrinsic(bcx, false, ty, llresult, C_u8(ccx, 0), C_uint(ccx, 1usize));
187             }
188             C_nil(ccx)
189         }
190         // Effectively no-ops
191         "uninit" | "forget" => {
192             C_nil(ccx)
193         }
194         "needs_drop" => {
195             let tp_ty = substs.type_at(0);
196
197             C_bool(ccx, bcx.ccx.shared().type_needs_drop(tp_ty))
198         }
199         "offset" => {
200             let ptr = llargs[0];
201             let offset = llargs[1];
202             bcx.inbounds_gep(ptr, &[offset])
203         }
204         "arith_offset" => {
205             let ptr = llargs[0];
206             let offset = llargs[1];
207             bcx.gep(ptr, &[offset])
208         }
209
210         "copy_nonoverlapping" => {
211             copy_intrinsic(bcx, false, false, substs.type_at(0), llargs[1], llargs[0], llargs[2])
212         }
213         "copy" => {
214             copy_intrinsic(bcx, true, false, substs.type_at(0), llargs[1], llargs[0], llargs[2])
215         }
216         "write_bytes" => {
217             memset_intrinsic(bcx, false, substs.type_at(0), llargs[0], llargs[1], llargs[2])
218         }
219
220         "volatile_copy_nonoverlapping_memory" => {
221             copy_intrinsic(bcx, false, true, substs.type_at(0), llargs[0], llargs[1], llargs[2])
222         }
223         "volatile_copy_memory" => {
224             copy_intrinsic(bcx, true, true, substs.type_at(0), llargs[0], llargs[1], llargs[2])
225         }
226         "volatile_set_memory" => {
227             memset_intrinsic(bcx, true, substs.type_at(0), llargs[0], llargs[1], llargs[2])
228         }
229         "volatile_load" => {
230             let tp_ty = substs.type_at(0);
231             let mut ptr = llargs[0];
232             if let Some(ty) = fn_ty.ret.cast {
233                 ptr = bcx.pointercast(ptr, ty.ptr_to());
234             }
235             let load = bcx.volatile_load(ptr);
236             unsafe {
237                 llvm::LLVMSetAlignment(load, type_of::align_of(ccx, tp_ty));
238             }
239             to_immediate(bcx, load, tp_ty)
240         },
241         "volatile_store" => {
242             let tp_ty = substs.type_at(0);
243             if type_is_fat_ptr(bcx.ccx, tp_ty) {
244                 bcx.volatile_store(llargs[1], get_dataptr(bcx, llargs[0]));
245                 bcx.volatile_store(llargs[2], get_meta(bcx, llargs[0]));
246             } else {
247                 let val = if fn_ty.args[1].is_indirect() {
248                     bcx.load(llargs[1], None)
249                 } else {
250                     from_immediate(bcx, llargs[1])
251                 };
252                 let ptr = bcx.pointercast(llargs[0], val_ty(val).ptr_to());
253                 let store = bcx.volatile_store(val, ptr);
254                 unsafe {
255                     llvm::LLVMSetAlignment(store, type_of::align_of(ccx, tp_ty));
256                 }
257             }
258             C_nil(ccx)
259         },
260
261         "ctlz" | "cttz" | "ctpop" | "bswap" |
262         "add_with_overflow" | "sub_with_overflow" | "mul_with_overflow" |
263         "overflowing_add" | "overflowing_sub" | "overflowing_mul" |
264         "unchecked_div" | "unchecked_rem" => {
265             let sty = &arg_tys[0].sty;
266             match int_type_width_signed(sty, ccx) {
267                 Some((width, signed)) =>
268                     match name {
269                         "ctlz" | "cttz" => {
270                             let y = C_bool(bcx.ccx, false);
271                             let llfn = ccx.get_intrinsic(&format!("llvm.{}.i{}", name, width));
272                             bcx.call(llfn, &[llargs[0], y], None)
273                         }
274                         "ctpop" => bcx.call(ccx.get_intrinsic(&format!("llvm.ctpop.i{}", width)),
275                                         &llargs, None),
276                         "bswap" => {
277                             if width == 8 {
278                                 llargs[0] // byte swap a u8/i8 is just a no-op
279                             } else {
280                                 bcx.call(ccx.get_intrinsic(&format!("llvm.bswap.i{}", width)),
281                                         &llargs, None)
282                             }
283                         }
284                         "add_with_overflow" | "sub_with_overflow" | "mul_with_overflow" => {
285                             let intrinsic = format!("llvm.{}{}.with.overflow.i{}",
286                                                     if signed { 's' } else { 'u' },
287                                                     &name[..3], width);
288                             let llfn = bcx.ccx.get_intrinsic(&intrinsic);
289
290                             // Convert `i1` to a `bool`, and write it to the out parameter
291                             let val = bcx.call(llfn, &[llargs[0], llargs[1]], None);
292                             let result = bcx.extract_value(val, 0);
293                             let overflow = bcx.zext(bcx.extract_value(val, 1), Type::bool(ccx));
294                             bcx.store(result, bcx.struct_gep(llresult, 0), None);
295                             bcx.store(overflow, bcx.struct_gep(llresult, 1), None);
296
297                             C_nil(bcx.ccx)
298                         },
299                         "overflowing_add" => bcx.add(llargs[0], llargs[1]),
300                         "overflowing_sub" => bcx.sub(llargs[0], llargs[1]),
301                         "overflowing_mul" => bcx.mul(llargs[0], llargs[1]),
302                         "unchecked_div" =>
303                             if signed {
304                                 bcx.sdiv(llargs[0], llargs[1])
305                             } else {
306                                 bcx.udiv(llargs[0], llargs[1])
307                             },
308                         "unchecked_rem" =>
309                             if signed {
310                                 bcx.srem(llargs[0], llargs[1])
311                             } else {
312                                 bcx.urem(llargs[0], llargs[1])
313                             },
314                         _ => bug!(),
315                     },
316                 None => {
317                     span_invalid_monomorphization_error(
318                         tcx.sess, span,
319                         &format!("invalid monomorphization of `{}` intrinsic: \
320                                   expected basic integer type, found `{}`", name, sty));
321                         C_nil(ccx)
322                 }
323             }
324
325         },
326         "fadd_fast" | "fsub_fast" | "fmul_fast" | "fdiv_fast" | "frem_fast" => {
327             let sty = &arg_tys[0].sty;
328             match float_type_width(sty) {
329                 Some(_width) =>
330                     match name {
331                         "fadd_fast" => bcx.fadd_fast(llargs[0], llargs[1]),
332                         "fsub_fast" => bcx.fsub_fast(llargs[0], llargs[1]),
333                         "fmul_fast" => bcx.fmul_fast(llargs[0], llargs[1]),
334                         "fdiv_fast" => bcx.fdiv_fast(llargs[0], llargs[1]),
335                         "frem_fast" => bcx.frem_fast(llargs[0], llargs[1]),
336                         _ => bug!(),
337                     },
338                 None => {
339                     span_invalid_monomorphization_error(
340                         tcx.sess, span,
341                         &format!("invalid monomorphization of `{}` intrinsic: \
342                                   expected basic float type, found `{}`", name, sty));
343                         C_nil(ccx)
344                 }
345             }
346
347         },
348
349         "discriminant_value" => {
350             let val_ty = substs.type_at(0);
351             match val_ty.sty {
352                 ty::TyAdt(adt, ..) if adt.is_enum() => {
353                     adt::trans_get_discr(bcx, val_ty, llargs[0], Alignment::AbiAligned,
354                                          Some(llret_ty), true)
355                 }
356                 _ => C_null(llret_ty)
357             }
358         }
359         name if name.starts_with("simd_") => {
360             generic_simd_intrinsic(bcx, name,
361                                    callee_ty,
362                                    &llargs,
363                                    ret_ty, llret_ty,
364                                    span)
365         }
366         // This requires that atomic intrinsics follow a specific naming pattern:
367         // "atomic_<operation>[_<ordering>]", and no ordering means SeqCst
368         name if name.starts_with("atomic_") => {
369             use llvm::AtomicOrdering::*;
370
371             let split: Vec<&str> = name.split('_').collect();
372
373             let is_cxchg = split[1] == "cxchg" || split[1] == "cxchgweak";
374             let (order, failorder) = match split.len() {
375                 2 => (SequentiallyConsistent, SequentiallyConsistent),
376                 3 => match split[2] {
377                     "unordered" => (Unordered, Unordered),
378                     "relaxed" => (Monotonic, Monotonic),
379                     "acq"     => (Acquire, Acquire),
380                     "rel"     => (Release, Monotonic),
381                     "acqrel"  => (AcquireRelease, Acquire),
382                     "failrelaxed" if is_cxchg =>
383                         (SequentiallyConsistent, Monotonic),
384                     "failacq" if is_cxchg =>
385                         (SequentiallyConsistent, Acquire),
386                     _ => ccx.sess().fatal("unknown ordering in atomic intrinsic")
387                 },
388                 4 => match (split[2], split[3]) {
389                     ("acq", "failrelaxed") if is_cxchg =>
390                         (Acquire, Monotonic),
391                     ("acqrel", "failrelaxed") if is_cxchg =>
392                         (AcquireRelease, Monotonic),
393                     _ => ccx.sess().fatal("unknown ordering in atomic intrinsic")
394                 },
395                 _ => ccx.sess().fatal("Atomic intrinsic not in correct format"),
396             };
397
398             let invalid_monomorphization = |sty| {
399                 span_invalid_monomorphization_error(tcx.sess, span,
400                     &format!("invalid monomorphization of `{}` intrinsic: \
401                               expected basic integer type, found `{}`", name, sty));
402             };
403
404             match split[1] {
405                 "cxchg" | "cxchgweak" => {
406                     let sty = &substs.type_at(0).sty;
407                     if int_type_width_signed(sty, ccx).is_some() {
408                         let weak = if split[1] == "cxchgweak" { llvm::True } else { llvm::False };
409                         let val = bcx.atomic_cmpxchg(llargs[0], llargs[1], llargs[2], order,
410                             failorder, weak);
411                         let result = bcx.extract_value(val, 0);
412                         let success = bcx.zext(bcx.extract_value(val, 1), Type::bool(bcx.ccx));
413                         bcx.store(result, bcx.struct_gep(llresult, 0), None);
414                         bcx.store(success, bcx.struct_gep(llresult, 1), None);
415                     } else {
416                         invalid_monomorphization(sty);
417                     }
418                     C_nil(ccx)
419                 }
420
421                 "load" => {
422                     let sty = &substs.type_at(0).sty;
423                     if int_type_width_signed(sty, ccx).is_some() {
424                         bcx.atomic_load(llargs[0], order)
425                     } else {
426                         invalid_monomorphization(sty);
427                         C_nil(ccx)
428                     }
429                 }
430
431                 "store" => {
432                     let sty = &substs.type_at(0).sty;
433                     if int_type_width_signed(sty, ccx).is_some() {
434                         bcx.atomic_store(llargs[1], llargs[0], order);
435                     } else {
436                         invalid_monomorphization(sty);
437                     }
438                     C_nil(ccx)
439                 }
440
441                 "fence" => {
442                     bcx.atomic_fence(order, llvm::SynchronizationScope::CrossThread);
443                     C_nil(ccx)
444                 }
445
446                 "singlethreadfence" => {
447                     bcx.atomic_fence(order, llvm::SynchronizationScope::SingleThread);
448                     C_nil(ccx)
449                 }
450
451                 // These are all AtomicRMW ops
452                 op => {
453                     let atom_op = match op {
454                         "xchg"  => llvm::AtomicXchg,
455                         "xadd"  => llvm::AtomicAdd,
456                         "xsub"  => llvm::AtomicSub,
457                         "and"   => llvm::AtomicAnd,
458                         "nand"  => llvm::AtomicNand,
459                         "or"    => llvm::AtomicOr,
460                         "xor"   => llvm::AtomicXor,
461                         "max"   => llvm::AtomicMax,
462                         "min"   => llvm::AtomicMin,
463                         "umax"  => llvm::AtomicUMax,
464                         "umin"  => llvm::AtomicUMin,
465                         _ => ccx.sess().fatal("unknown atomic operation")
466                     };
467
468                     let sty = &substs.type_at(0).sty;
469                     if int_type_width_signed(sty, ccx).is_some() {
470                         bcx.atomic_rmw(atom_op, llargs[0], llargs[1], order)
471                     } else {
472                         invalid_monomorphization(sty);
473                         C_nil(ccx)
474                     }
475                 }
476             }
477         }
478
479         _ => {
480             let intr = match Intrinsic::find(&name) {
481                 Some(intr) => intr,
482                 None => bug!("unknown intrinsic '{}'", name),
483             };
484             fn one<T>(x: Vec<T>) -> T {
485                 assert_eq!(x.len(), 1);
486                 x.into_iter().next().unwrap()
487             }
488             fn ty_to_type(ccx: &CrateContext, t: &intrinsics::Type,
489                           any_changes_needed: &mut bool) -> Vec<Type> {
490                 use intrinsics::Type::*;
491                 match *t {
492                     Void => vec![Type::void(ccx)],
493                     Integer(_signed, width, llvm_width) => {
494                         *any_changes_needed |= width != llvm_width;
495                         vec![Type::ix(ccx, llvm_width as u64)]
496                     }
497                     Float(x) => {
498                         match x {
499                             32 => vec![Type::f32(ccx)],
500                             64 => vec![Type::f64(ccx)],
501                             _ => bug!()
502                         }
503                     }
504                     Pointer(ref t, ref llvm_elem, _const) => {
505                         *any_changes_needed |= llvm_elem.is_some();
506
507                         let t = llvm_elem.as_ref().unwrap_or(t);
508                         let elem = one(ty_to_type(ccx, t, any_changes_needed));
509                         vec![elem.ptr_to()]
510                     }
511                     Vector(ref t, ref llvm_elem, length) => {
512                         *any_changes_needed |= llvm_elem.is_some();
513
514                         let t = llvm_elem.as_ref().unwrap_or(t);
515                         let elem = one(ty_to_type(ccx, t, any_changes_needed));
516                         vec![Type::vector(&elem, length as u64)]
517                     }
518                     Aggregate(false, ref contents) => {
519                         let elems = contents.iter()
520                                             .map(|t| one(ty_to_type(ccx, t, any_changes_needed)))
521                                             .collect::<Vec<_>>();
522                         vec![Type::struct_(ccx, &elems, false)]
523                     }
524                     Aggregate(true, ref contents) => {
525                         *any_changes_needed = true;
526                         contents.iter()
527                                 .flat_map(|t| ty_to_type(ccx, t, any_changes_needed))
528                                 .collect()
529                     }
530                 }
531             }
532
533             // This allows an argument list like `foo, (bar, baz),
534             // qux` to be converted into `foo, bar, baz, qux`, integer
535             // arguments to be truncated as needed and pointers to be
536             // cast.
537             fn modify_as_needed<'a, 'tcx>(bcx: &Builder<'a, 'tcx>,
538                                           t: &intrinsics::Type,
539                                           arg_type: Ty<'tcx>,
540                                           llarg: ValueRef)
541                                           -> Vec<ValueRef>
542             {
543                 match *t {
544                     intrinsics::Type::Aggregate(true, ref contents) => {
545                         // We found a tuple that needs squishing! So
546                         // run over the tuple and load each field.
547                         //
548                         // This assumes the type is "simple", i.e. no
549                         // destructors, and the contents are SIMD
550                         // etc.
551                         assert!(!bcx.ccx.shared().type_needs_drop(arg_type));
552                         let arg = LvalueRef::new_sized_ty(llarg, arg_type, Alignment::AbiAligned);
553                         (0..contents.len()).map(|i| {
554                             let (ptr, align) = arg.trans_field_ptr(bcx, i);
555                             bcx.load(ptr, align.to_align())
556                         }).collect()
557                     }
558                     intrinsics::Type::Pointer(_, Some(ref llvm_elem), _) => {
559                         let llvm_elem = one(ty_to_type(bcx.ccx, llvm_elem, &mut false));
560                         vec![bcx.pointercast(llarg, llvm_elem.ptr_to())]
561                     }
562                     intrinsics::Type::Vector(_, Some(ref llvm_elem), length) => {
563                         let llvm_elem = one(ty_to_type(bcx.ccx, llvm_elem, &mut false));
564                         vec![bcx.bitcast(llarg, Type::vector(&llvm_elem, length as u64))]
565                     }
566                     intrinsics::Type::Integer(_, width, llvm_width) if width != llvm_width => {
567                         // the LLVM intrinsic uses a smaller integer
568                         // size than the C intrinsic's signature, so
569                         // we have to trim it down here.
570                         vec![bcx.trunc(llarg, Type::ix(bcx.ccx, llvm_width as u64))]
571                     }
572                     _ => vec![llarg],
573                 }
574             }
575
576
577             let mut any_changes_needed = false;
578             let inputs = intr.inputs.iter()
579                                     .flat_map(|t| ty_to_type(ccx, t, &mut any_changes_needed))
580                                     .collect::<Vec<_>>();
581
582             let mut out_changes = false;
583             let outputs = one(ty_to_type(ccx, &intr.output, &mut out_changes));
584             // outputting a flattened aggregate is nonsense
585             assert!(!out_changes);
586
587             let llargs = if !any_changes_needed {
588                 // no aggregates to flatten, so no change needed
589                 llargs.to_vec()
590             } else {
591                 // there are some aggregates that need to be flattened
592                 // in the LLVM call, so we need to run over the types
593                 // again to find them and extract the arguments
594                 intr.inputs.iter()
595                            .zip(llargs)
596                            .zip(arg_tys)
597                            .flat_map(|((t, llarg), ty)| modify_as_needed(bcx, t, ty, *llarg))
598                            .collect()
599             };
600             assert_eq!(inputs.len(), llargs.len());
601
602             let val = match intr.definition {
603                 intrinsics::IntrinsicDef::Named(name) => {
604                     let f = declare::declare_cfn(ccx,
605                                                  name,
606                                                  Type::func(&inputs, &outputs));
607                     bcx.call(f, &llargs, None)
608                 }
609             };
610
611             match *intr.output {
612                 intrinsics::Type::Aggregate(flatten, ref elems) => {
613                     // the output is a tuple so we need to munge it properly
614                     assert!(!flatten);
615
616                     for i in 0..elems.len() {
617                         let val = bcx.extract_value(val, i);
618                         bcx.store(val, bcx.struct_gep(llresult, i), None);
619                     }
620                     C_nil(ccx)
621                 }
622                 _ => val,
623             }
624         }
625     };
626
627     if val_ty(llval) != Type::void(ccx) && machine::llsize_of_alloc(ccx, val_ty(llval)) != 0 {
628         if let Some(ty) = fn_ty.ret.cast {
629             let ptr = bcx.pointercast(llresult, ty.ptr_to());
630             bcx.store(llval, ptr, Some(type_of::align_of(ccx, ret_ty)));
631         } else {
632             store_ty(bcx, llval, llresult, Alignment::AbiAligned, ret_ty);
633         }
634     }
635 }
636
637 fn copy_intrinsic<'a, 'tcx>(bcx: &Builder<'a, 'tcx>,
638                             allow_overlap: bool,
639                             volatile: bool,
640                             tp_ty: Ty<'tcx>,
641                             dst: ValueRef,
642                             src: ValueRef,
643                             count: ValueRef)
644                             -> ValueRef {
645     let ccx = bcx.ccx;
646     let lltp_ty = type_of::type_of(ccx, tp_ty);
647     let align = C_i32(ccx, type_of::align_of(ccx, tp_ty) as i32);
648     let size = machine::llsize_of(ccx, lltp_ty);
649     let int_size = machine::llbitsize_of_real(ccx, ccx.int_type());
650
651     let operation = if allow_overlap {
652         "memmove"
653     } else {
654         "memcpy"
655     };
656
657     let name = format!("llvm.{}.p0i8.p0i8.i{}", operation, int_size);
658
659     let dst_ptr = bcx.pointercast(dst, Type::i8p(ccx));
660     let src_ptr = bcx.pointercast(src, Type::i8p(ccx));
661     let llfn = ccx.get_intrinsic(&name);
662
663     bcx.call(llfn,
664         &[dst_ptr,
665         src_ptr,
666         bcx.mul(size, count),
667         align,
668         C_bool(ccx, volatile)],
669         None)
670 }
671
672 fn memset_intrinsic<'a, 'tcx>(
673     bcx: &Builder<'a, 'tcx>,
674     volatile: bool,
675     ty: Ty<'tcx>,
676     dst: ValueRef,
677     val: ValueRef,
678     count: ValueRef
679 ) -> ValueRef {
680     let ccx = bcx.ccx;
681     let align = C_i32(ccx, type_of::align_of(ccx, ty) as i32);
682     let lltp_ty = type_of::type_of(ccx, ty);
683     let size = machine::llsize_of(ccx, lltp_ty);
684     let dst = bcx.pointercast(dst, Type::i8p(ccx));
685     call_memset(bcx, dst, val, bcx.mul(size, count), align, volatile)
686 }
687
688 fn try_intrinsic<'a, 'tcx>(
689     bcx: &Builder<'a, 'tcx>,
690     ccx: &CrateContext,
691     func: ValueRef,
692     data: ValueRef,
693     local_ptr: ValueRef,
694     dest: ValueRef,
695 ) {
696     if bcx.sess().no_landing_pads() {
697         bcx.call(func, &[data], None);
698         bcx.store(C_null(Type::i8p(&bcx.ccx)), dest, None);
699     } else if wants_msvc_seh(bcx.sess()) {
700         trans_msvc_try(bcx, ccx, func, data, local_ptr, dest);
701     } else {
702         trans_gnu_try(bcx, ccx, func, data, local_ptr, dest);
703     }
704 }
705
706 // MSVC's definition of the `rust_try` function.
707 //
708 // This implementation uses the new exception handling instructions in LLVM
709 // which have support in LLVM for SEH on MSVC targets. Although these
710 // instructions are meant to work for all targets, as of the time of this
711 // writing, however, LLVM does not recommend the usage of these new instructions
712 // as the old ones are still more optimized.
713 fn trans_msvc_try<'a, 'tcx>(bcx: &Builder<'a, 'tcx>,
714                             ccx: &CrateContext,
715                             func: ValueRef,
716                             data: ValueRef,
717                             local_ptr: ValueRef,
718                             dest: ValueRef) {
719     let llfn = get_rust_try_fn(ccx, &mut |bcx| {
720         let ccx = bcx.ccx;
721
722         bcx.set_personality_fn(bcx.ccx.eh_personality());
723
724         let normal = bcx.build_sibling_block("normal");
725         let catchswitch = bcx.build_sibling_block("catchswitch");
726         let catchpad = bcx.build_sibling_block("catchpad");
727         let caught = bcx.build_sibling_block("caught");
728
729         let func = llvm::get_param(bcx.llfn(), 0);
730         let data = llvm::get_param(bcx.llfn(), 1);
731         let local_ptr = llvm::get_param(bcx.llfn(), 2);
732
733         // We're generating an IR snippet that looks like:
734         //
735         //   declare i32 @rust_try(%func, %data, %ptr) {
736         //      %slot = alloca i64*
737         //      invoke %func(%data) to label %normal unwind label %catchswitch
738         //
739         //   normal:
740         //      ret i32 0
741         //
742         //   catchswitch:
743         //      %cs = catchswitch within none [%catchpad] unwind to caller
744         //
745         //   catchpad:
746         //      %tok = catchpad within %cs [%type_descriptor, 0, %slot]
747         //      %ptr[0] = %slot[0]
748         //      %ptr[1] = %slot[1]
749         //      catchret from %tok to label %caught
750         //
751         //   caught:
752         //      ret i32 1
753         //   }
754         //
755         // This structure follows the basic usage of throw/try/catch in LLVM.
756         // For example, compile this C++ snippet to see what LLVM generates:
757         //
758         //      #include <stdint.h>
759         //
760         //      int bar(void (*foo)(void), uint64_t *ret) {
761         //          try {
762         //              foo();
763         //              return 0;
764         //          } catch(uint64_t a[2]) {
765         //              ret[0] = a[0];
766         //              ret[1] = a[1];
767         //              return 1;
768         //          }
769         //      }
770         //
771         // More information can be found in libstd's seh.rs implementation.
772         let i64p = Type::i64(ccx).ptr_to();
773         let slot = bcx.alloca(i64p, "slot");
774         bcx.invoke(func, &[data], normal.llbb(), catchswitch.llbb(),
775             None);
776
777         normal.ret(C_i32(ccx, 0));
778
779         let cs = catchswitch.catch_switch(None, None, 1);
780         catchswitch.add_handler(cs, catchpad.llbb());
781
782         let tcx = ccx.tcx();
783         let tydesc = match tcx.lang_items.msvc_try_filter() {
784             Some(did) => ::consts::get_static(ccx, did),
785             None => bug!("msvc_try_filter not defined"),
786         };
787         let tok = catchpad.catch_pad(cs, &[tydesc, C_i32(ccx, 0), slot]);
788         let addr = catchpad.load(slot, None);
789         let arg1 = catchpad.load(addr, None);
790         let val1 = C_i32(ccx, 1);
791         let arg2 = catchpad.load(catchpad.inbounds_gep(addr, &[val1]), None);
792         let local_ptr = catchpad.bitcast(local_ptr, i64p);
793         catchpad.store(arg1, local_ptr, None);
794         catchpad.store(arg2, catchpad.inbounds_gep(local_ptr, &[val1]), None);
795         catchpad.catch_ret(tok, caught.llbb());
796
797         caught.ret(C_i32(ccx, 1));
798     });
799
800     // Note that no invoke is used here because by definition this function
801     // can't panic (that's what it's catching).
802     let ret = bcx.call(llfn, &[func, data, local_ptr], None);
803     bcx.store(ret, dest, None);
804 }
805
806 // Definition of the standard "try" function for Rust using the GNU-like model
807 // of exceptions (e.g. the normal semantics of LLVM's landingpad and invoke
808 // instructions).
809 //
810 // This translation is a little surprising because we always call a shim
811 // function instead of inlining the call to `invoke` manually here. This is done
812 // because in LLVM we're only allowed to have one personality per function
813 // definition. The call to the `try` intrinsic is being inlined into the
814 // function calling it, and that function may already have other personality
815 // functions in play. By calling a shim we're guaranteed that our shim will have
816 // the right personality function.
817 fn trans_gnu_try<'a, 'tcx>(bcx: &Builder<'a, 'tcx>,
818                            ccx: &CrateContext,
819                            func: ValueRef,
820                            data: ValueRef,
821                            local_ptr: ValueRef,
822                            dest: ValueRef) {
823     let llfn = get_rust_try_fn(ccx, &mut |bcx| {
824         let ccx = bcx.ccx;
825
826         // Translates the shims described above:
827         //
828         //   bcx:
829         //      invoke %func(%args...) normal %normal unwind %catch
830         //
831         //   normal:
832         //      ret 0
833         //
834         //   catch:
835         //      (ptr, _) = landingpad
836         //      store ptr, %local_ptr
837         //      ret 1
838         //
839         // Note that the `local_ptr` data passed into the `try` intrinsic is
840         // expected to be `*mut *mut u8` for this to actually work, but that's
841         // managed by the standard library.
842
843         let then = bcx.build_sibling_block("then");
844         let catch = bcx.build_sibling_block("catch");
845
846         let func = llvm::get_param(bcx.llfn(), 0);
847         let data = llvm::get_param(bcx.llfn(), 1);
848         let local_ptr = llvm::get_param(bcx.llfn(), 2);
849         bcx.invoke(func, &[data], then.llbb(), catch.llbb(), None);
850         then.ret(C_i32(ccx, 0));
851
852         // Type indicator for the exception being thrown.
853         //
854         // The first value in this tuple is a pointer to the exception object
855         // being thrown.  The second value is a "selector" indicating which of
856         // the landing pad clauses the exception's type had been matched to.
857         // rust_try ignores the selector.
858         let lpad_ty = Type::struct_(ccx, &[Type::i8p(ccx), Type::i32(ccx)],
859                                     false);
860         let vals = catch.landing_pad(lpad_ty, bcx.ccx.eh_personality(), 1, catch.llfn());
861         catch.add_clause(vals, C_null(Type::i8p(ccx)));
862         let ptr = catch.extract_value(vals, 0);
863         catch.store(ptr, catch.bitcast(local_ptr, Type::i8p(ccx).ptr_to()), None);
864         catch.ret(C_i32(ccx, 1));
865     });
866
867     // Note that no invoke is used here because by definition this function
868     // can't panic (that's what it's catching).
869     let ret = bcx.call(llfn, &[func, data, local_ptr], None);
870     bcx.store(ret, dest, None);
871 }
872
873 // Helper function to give a Block to a closure to translate a shim function.
874 // This is currently primarily used for the `try` intrinsic functions above.
875 fn gen_fn<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
876                     name: &str,
877                     inputs: Vec<Ty<'tcx>>,
878                     output: Ty<'tcx>,
879                     trans: &mut for<'b> FnMut(Builder<'b, 'tcx>))
880                     -> ValueRef {
881     let rust_fn_ty = ccx.tcx().mk_fn_ptr(ty::Binder(ccx.tcx().mk_fn_sig(
882         inputs.into_iter(),
883         output,
884         false,
885         hir::Unsafety::Unsafe,
886         Abi::Rust
887     )));
888     let llfn = declare::define_internal_fn(ccx, name, rust_fn_ty);
889     let bcx = Builder::new_block(ccx, llfn, "entry-block");
890     trans(bcx);
891     llfn
892 }
893
894 // Helper function used to get a handle to the `__rust_try` function used to
895 // catch exceptions.
896 //
897 // This function is only generated once and is then cached.
898 fn get_rust_try_fn<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
899                              trans: &mut for<'b> FnMut(Builder<'b, 'tcx>))
900                              -> ValueRef {
901     if let Some(llfn) = ccx.rust_try_fn().get() {
902         return llfn;
903     }
904
905     // Define the type up front for the signature of the rust_try function.
906     let tcx = ccx.tcx();
907     let i8p = tcx.mk_mut_ptr(tcx.types.i8);
908     let fn_ty = tcx.mk_fn_ptr(ty::Binder(tcx.mk_fn_sig(
909         iter::once(i8p),
910         tcx.mk_nil(),
911         false,
912         hir::Unsafety::Unsafe,
913         Abi::Rust
914     )));
915     let output = tcx.types.i32;
916     let rust_try = gen_fn(ccx, "__rust_try", vec![fn_ty, i8p, i8p], output, trans);
917     ccx.rust_try_fn().set(Some(rust_try));
918     return rust_try
919 }
920
921 fn span_invalid_monomorphization_error(a: &Session, b: Span, c: &str) {
922     span_err!(a, b, E0511, "{}", c);
923 }
924
925 fn generic_simd_intrinsic<'a, 'tcx>(
926     bcx: &Builder<'a, 'tcx>,
927     name: &str,
928     callee_ty: Ty<'tcx>,
929     llargs: &[ValueRef],
930     ret_ty: Ty<'tcx>,
931     llret_ty: Type,
932     span: Span
933 ) -> ValueRef {
934     // macros for error handling:
935     macro_rules! emit_error {
936         ($msg: tt) => {
937             emit_error!($msg, )
938         };
939         ($msg: tt, $($fmt: tt)*) => {
940             span_invalid_monomorphization_error(
941                 bcx.sess(), span,
942                 &format!(concat!("invalid monomorphization of `{}` intrinsic: ",
943                                  $msg),
944                          name, $($fmt)*));
945         }
946     }
947     macro_rules! require {
948         ($cond: expr, $($fmt: tt)*) => {
949             if !$cond {
950                 emit_error!($($fmt)*);
951                 return C_nil(bcx.ccx)
952             }
953         }
954     }
955     macro_rules! require_simd {
956         ($ty: expr, $position: expr) => {
957             require!($ty.is_simd(), "expected SIMD {} type, found non-SIMD `{}`", $position, $ty)
958         }
959     }
960
961
962
963     let tcx = bcx.tcx();
964     let sig = tcx.erase_late_bound_regions_and_normalize(&callee_ty.fn_sig());
965     let arg_tys = sig.inputs();
966
967     // every intrinsic takes a SIMD vector as its first argument
968     require_simd!(arg_tys[0], "input");
969     let in_ty = arg_tys[0];
970     let in_elem = arg_tys[0].simd_type(tcx);
971     let in_len = arg_tys[0].simd_size(tcx);
972
973     let comparison = match name {
974         "simd_eq" => Some(hir::BiEq),
975         "simd_ne" => Some(hir::BiNe),
976         "simd_lt" => Some(hir::BiLt),
977         "simd_le" => Some(hir::BiLe),
978         "simd_gt" => Some(hir::BiGt),
979         "simd_ge" => Some(hir::BiGe),
980         _ => None
981     };
982
983     if let Some(cmp_op) = comparison {
984         require_simd!(ret_ty, "return");
985
986         let out_len = ret_ty.simd_size(tcx);
987         require!(in_len == out_len,
988                  "expected return type with length {} (same as input type `{}`), \
989                   found `{}` with length {}",
990                  in_len, in_ty,
991                  ret_ty, out_len);
992         require!(llret_ty.element_type().kind() == llvm::Integer,
993                  "expected return type with integer elements, found `{}` with non-integer `{}`",
994                  ret_ty,
995                  ret_ty.simd_type(tcx));
996
997         return compare_simd_types(bcx,
998                                   llargs[0],
999                                   llargs[1],
1000                                   in_elem,
1001                                   llret_ty,
1002                                   cmp_op)
1003     }
1004
1005     if name.starts_with("simd_shuffle") {
1006         let n: usize = match name["simd_shuffle".len()..].parse() {
1007             Ok(n) => n,
1008             Err(_) => span_bug!(span,
1009                                 "bad `simd_shuffle` instruction only caught in trans?")
1010         };
1011
1012         require_simd!(ret_ty, "return");
1013
1014         let out_len = ret_ty.simd_size(tcx);
1015         require!(out_len == n,
1016                  "expected return type of length {}, found `{}` with length {}",
1017                  n, ret_ty, out_len);
1018         require!(in_elem == ret_ty.simd_type(tcx),
1019                  "expected return element type `{}` (element of input `{}`), \
1020                   found `{}` with element type `{}`",
1021                  in_elem, in_ty,
1022                  ret_ty, ret_ty.simd_type(tcx));
1023
1024         let total_len = in_len as u128 * 2;
1025
1026         let vector = llargs[2];
1027
1028         let indices: Option<Vec<_>> = (0..n)
1029             .map(|i| {
1030                 let arg_idx = i;
1031                 let val = const_get_elt(vector, &[i as libc::c_uint]);
1032                 match const_to_opt_u128(val, true) {
1033                     None => {
1034                         emit_error!("shuffle index #{} is not a constant", arg_idx);
1035                         None
1036                     }
1037                     Some(idx) if idx >= total_len => {
1038                         emit_error!("shuffle index #{} is out of bounds (limit {})",
1039                                     arg_idx, total_len);
1040                         None
1041                     }
1042                     Some(idx) => Some(C_i32(bcx.ccx, idx as i32)),
1043                 }
1044             })
1045             .collect();
1046         let indices = match indices {
1047             Some(i) => i,
1048             None => return C_null(llret_ty)
1049         };
1050
1051         return bcx.shuffle_vector(llargs[0], llargs[1], C_vector(&indices))
1052     }
1053
1054     if name == "simd_insert" {
1055         require!(in_elem == arg_tys[2],
1056                  "expected inserted type `{}` (element of input `{}`), found `{}`",
1057                  in_elem, in_ty, arg_tys[2]);
1058         return bcx.insert_element(llargs[0], llargs[2], llargs[1])
1059     }
1060     if name == "simd_extract" {
1061         require!(ret_ty == in_elem,
1062                  "expected return type `{}` (element of input `{}`), found `{}`",
1063                  in_elem, in_ty, ret_ty);
1064         return bcx.extract_element(llargs[0], llargs[1])
1065     }
1066
1067     if name == "simd_cast" {
1068         require_simd!(ret_ty, "return");
1069         let out_len = ret_ty.simd_size(tcx);
1070         require!(in_len == out_len,
1071                  "expected return type with length {} (same as input type `{}`), \
1072                   found `{}` with length {}",
1073                  in_len, in_ty,
1074                  ret_ty, out_len);
1075         // casting cares about nominal type, not just structural type
1076         let out_elem = ret_ty.simd_type(tcx);
1077
1078         if in_elem == out_elem { return llargs[0]; }
1079
1080         enum Style { Float, Int(/* is signed? */ bool), Unsupported }
1081
1082         let (in_style, in_width) = match in_elem.sty {
1083             // vectors of pointer-sized integers should've been
1084             // disallowed before here, so this unwrap is safe.
1085             ty::TyInt(i) => (Style::Int(true), i.bit_width().unwrap()),
1086             ty::TyUint(u) => (Style::Int(false), u.bit_width().unwrap()),
1087             ty::TyFloat(f) => (Style::Float, f.bit_width()),
1088             _ => (Style::Unsupported, 0)
1089         };
1090         let (out_style, out_width) = match out_elem.sty {
1091             ty::TyInt(i) => (Style::Int(true), i.bit_width().unwrap()),
1092             ty::TyUint(u) => (Style::Int(false), u.bit_width().unwrap()),
1093             ty::TyFloat(f) => (Style::Float, f.bit_width()),
1094             _ => (Style::Unsupported, 0)
1095         };
1096
1097         match (in_style, out_style) {
1098             (Style::Int(in_is_signed), Style::Int(_)) => {
1099                 return match in_width.cmp(&out_width) {
1100                     Ordering::Greater => bcx.trunc(llargs[0], llret_ty),
1101                     Ordering::Equal => llargs[0],
1102                     Ordering::Less => if in_is_signed {
1103                         bcx.sext(llargs[0], llret_ty)
1104                     } else {
1105                         bcx.zext(llargs[0], llret_ty)
1106                     }
1107                 }
1108             }
1109             (Style::Int(in_is_signed), Style::Float) => {
1110                 return if in_is_signed {
1111                     bcx.sitofp(llargs[0], llret_ty)
1112                 } else {
1113                     bcx.uitofp(llargs[0], llret_ty)
1114                 }
1115             }
1116             (Style::Float, Style::Int(out_is_signed)) => {
1117                 return if out_is_signed {
1118                     bcx.fptosi(llargs[0], llret_ty)
1119                 } else {
1120                     bcx.fptoui(llargs[0], llret_ty)
1121                 }
1122             }
1123             (Style::Float, Style::Float) => {
1124                 return match in_width.cmp(&out_width) {
1125                     Ordering::Greater => bcx.fptrunc(llargs[0], llret_ty),
1126                     Ordering::Equal => llargs[0],
1127                     Ordering::Less => bcx.fpext(llargs[0], llret_ty)
1128                 }
1129             }
1130             _ => {/* Unsupported. Fallthrough. */}
1131         }
1132         require!(false,
1133                  "unsupported cast from `{}` with element `{}` to `{}` with element `{}`",
1134                  in_ty, in_elem,
1135                  ret_ty, out_elem);
1136     }
1137     macro_rules! arith {
1138         ($($name: ident: $($($p: ident),* => $call: ident),*;)*) => {
1139             $(
1140                 if name == stringify!($name) {
1141                     match in_elem.sty {
1142                         $(
1143                             $(ty::$p(_))|* => {
1144                                 return bcx.$call(llargs[0], llargs[1])
1145                             }
1146                             )*
1147                         _ => {},
1148                     }
1149                     require!(false,
1150                              "unsupported operation on `{}` with element `{}`",
1151                              in_ty,
1152                              in_elem)
1153                 })*
1154         }
1155     }
1156     arith! {
1157         simd_add: TyUint, TyInt => add, TyFloat => fadd;
1158         simd_sub: TyUint, TyInt => sub, TyFloat => fsub;
1159         simd_mul: TyUint, TyInt => mul, TyFloat => fmul;
1160         simd_div: TyFloat => fdiv;
1161         simd_shl: TyUint, TyInt => shl;
1162         simd_shr: TyUint => lshr, TyInt => ashr;
1163         simd_and: TyUint, TyInt => and;
1164         simd_or: TyUint, TyInt => or;
1165         simd_xor: TyUint, TyInt => xor;
1166     }
1167     span_bug!(span, "unknown SIMD intrinsic");
1168 }
1169
1170 // Returns the width of an int TypeVariant, and if it's signed or not
1171 // Returns None if the type is not an integer
1172 // FIXME: there’s multiple of this functions, investigate using some of the already existing
1173 // stuffs.
1174 fn int_type_width_signed<'tcx>(sty: &ty::TypeVariants<'tcx>, ccx: &CrateContext)
1175         -> Option<(u64, bool)> {
1176     use rustc::ty::{TyInt, TyUint};
1177     match *sty {
1178         TyInt(t) => Some((match t {
1179             ast::IntTy::Is => {
1180                 match &ccx.tcx().sess.target.target.target_pointer_width[..] {
1181                     "16" => 16,
1182                     "32" => 32,
1183                     "64" => 64,
1184                     tws => bug!("Unsupported target word size for isize: {}", tws),
1185                 }
1186             },
1187             ast::IntTy::I8 => 8,
1188             ast::IntTy::I16 => 16,
1189             ast::IntTy::I32 => 32,
1190             ast::IntTy::I64 => 64,
1191             ast::IntTy::I128 => 128,
1192         }, true)),
1193         TyUint(t) => Some((match t {
1194             ast::UintTy::Us => {
1195                 match &ccx.tcx().sess.target.target.target_pointer_width[..] {
1196                     "16" => 16,
1197                     "32" => 32,
1198                     "64" => 64,
1199                     tws => bug!("Unsupported target word size for usize: {}", tws),
1200                 }
1201             },
1202             ast::UintTy::U8 => 8,
1203             ast::UintTy::U16 => 16,
1204             ast::UintTy::U32 => 32,
1205             ast::UintTy::U64 => 64,
1206             ast::UintTy::U128 => 128,
1207         }, false)),
1208         _ => None,
1209     }
1210 }
1211
1212 // Returns the width of a float TypeVariant
1213 // Returns None if the type is not a float
1214 fn float_type_width<'tcx>(sty: &ty::TypeVariants<'tcx>)
1215         -> Option<u64> {
1216     use rustc::ty::TyFloat;
1217     match *sty {
1218         TyFloat(t) => Some(match t {
1219             ast::FloatTy::F32 => 32,
1220             ast::FloatTy::F64 => 64,
1221         }),
1222         _ => None,
1223     }
1224 }