compiler/rustc_codegen_llvm/src/intrinsic.rs

   1 use crate::abi::{Abi, FnAbi, LlvmType, PassMode};
   2 use crate::builder::Builder;
   3 use crate::context::CodegenCx;
   4 use crate::llvm;
   5 use crate::type_::Type;
   6 use crate::type_of::LayoutLlvmExt;
   7 use crate::va_arg::emit_va_arg;
   8 use crate::value::Value;
   9
  10 use rustc_codegen_ssa::base::{compare_simd_types, wants_msvc_seh};
  11 use rustc_codegen_ssa::common::span_invalid_monomorphization_error;
  12 use rustc_codegen_ssa::common::{IntPredicate, TypeKind};
  13 use rustc_codegen_ssa::mir::operand::OperandRef;
  14 use rustc_codegen_ssa::mir::place::PlaceRef;
  15 use rustc_codegen_ssa::traits::*;
  16 use rustc_hir as hir;
  17 use rustc_middle::ty::layout::{FnAbiExt, HasTyCtxt};
  18 use rustc_middle::ty::{self, Ty};
  19 use rustc_middle::{bug, span_bug};
  20 use rustc_span::{sym, symbol::kw, Span, Symbol};
  21 use rustc_target::abi::{self, HasDataLayout, LayoutOf, Primitive};
  22 use rustc_target::spec::PanicStrategy;
  23
  24 use std::cmp::Ordering;
  25 use std::iter;
  26
  27 fn get_simple_intrinsic(cx: &CodegenCx<'ll, '_>, name: Symbol) -> Option<&'ll Value> {
  28     let llvm_name = match name {
  29         sym::sqrtf32 => "llvm.sqrt.f32",
  30         sym::sqrtf64 => "llvm.sqrt.f64",
  31         sym::powif32 => "llvm.powi.f32",
  32         sym::powif64 => "llvm.powi.f64",
  33         sym::sinf32 => "llvm.sin.f32",
  34         sym::sinf64 => "llvm.sin.f64",
  35         sym::cosf32 => "llvm.cos.f32",
  36         sym::cosf64 => "llvm.cos.f64",
  37         sym::powf32 => "llvm.pow.f32",
  38         sym::powf64 => "llvm.pow.f64",
  39         sym::expf32 => "llvm.exp.f32",
  40         sym::expf64 => "llvm.exp.f64",
  41         sym::exp2f32 => "llvm.exp2.f32",
  42         sym::exp2f64 => "llvm.exp2.f64",
  43         sym::logf32 => "llvm.log.f32",
  44         sym::logf64 => "llvm.log.f64",
  45         sym::log10f32 => "llvm.log10.f32",
  46         sym::log10f64 => "llvm.log10.f64",
  47         sym::log2f32 => "llvm.log2.f32",
  48         sym::log2f64 => "llvm.log2.f64",
  49         sym::fmaf32 => "llvm.fma.f32",
  50         sym::fmaf64 => "llvm.fma.f64",
  51         sym::fabsf32 => "llvm.fabs.f32",
  52         sym::fabsf64 => "llvm.fabs.f64",
  53         sym::minnumf32 => "llvm.minnum.f32",
  54         sym::minnumf64 => "llvm.minnum.f64",
  55         sym::maxnumf32 => "llvm.maxnum.f32",
  56         sym::maxnumf64 => "llvm.maxnum.f64",
  57         sym::copysignf32 => "llvm.copysign.f32",
  58         sym::copysignf64 => "llvm.copysign.f64",
  59         sym::floorf32 => "llvm.floor.f32",
  60         sym::floorf64 => "llvm.floor.f64",
  61         sym::ceilf32 => "llvm.ceil.f32",
  62         sym::ceilf64 => "llvm.ceil.f64",
  63         sym::truncf32 => "llvm.trunc.f32",
  64         sym::truncf64 => "llvm.trunc.f64",
  65         sym::rintf32 => "llvm.rint.f32",
  66         sym::rintf64 => "llvm.rint.f64",
  67         sym::nearbyintf32 => "llvm.nearbyint.f32",
  68         sym::nearbyintf64 => "llvm.nearbyint.f64",
  69         sym::roundf32 => "llvm.round.f32",
  70         sym::roundf64 => "llvm.round.f64",
  71         _ => return None,
  72     };
  73     Some(cx.get_intrinsic(&llvm_name))
  74 }
  75
  76 impl IntrinsicCallMethods<'tcx> for Builder<'a, 'll, 'tcx> {
  77     fn codegen_intrinsic_call(
  78         &mut self,
  79         instance: ty::Instance<'tcx>,
  80         fn_abi: &FnAbi<'tcx, Ty<'tcx>>,
  81         args: &[OperandRef<'tcx, &'ll Value>],
  82         llresult: &'ll Value,
  83         span: Span,
  84     ) {
  85         let tcx = self.tcx;
  86         let callee_ty = instance.ty(tcx, ty::ParamEnv::reveal_all());
  87
  88         let (def_id, substs) = match *callee_ty.kind() {
  89             ty::FnDef(def_id, substs) => (def_id, substs),
  90             _ => bug!("expected fn item type, found {}", callee_ty),
  91         };
  92
  93         let sig = callee_ty.fn_sig(tcx);
  94         let sig = tcx.normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), sig);
  95         let arg_tys = sig.inputs();
  96         let ret_ty = sig.output();
  97         let name = tcx.item_name(def_id);
  98         let name_str = &*name.as_str();
  99
 100         let llret_ty = self.layout_of(ret_ty).llvm_type(self);
 101         let result = PlaceRef::new_sized(llresult, fn_abi.ret.layout);
 102
 103         let simple = get_simple_intrinsic(self, name);
 104         let llval = match name {
 105             _ if simple.is_some() => self.call(
 106                 simple.unwrap(),
 107                 &args.iter().map(|arg| arg.immediate()).collect::<Vec<_>>(),
 108                 None,
 109             ),
 110             sym::likely => {
 111                 let expect = self.get_intrinsic(&("llvm.expect.i1"));
 112                 self.call(expect, &[args[0].immediate(), self.const_bool(true)], None)
 113             }
 114             sym::unlikely => {
 115                 let expect = self.get_intrinsic(&("llvm.expect.i1"));
 116                 self.call(expect, &[args[0].immediate(), self.const_bool(false)], None)
 117             }
 118             kw::Try => {
 119                 try_intrinsic(
 120                     self,
 121                     args[0].immediate(),
 122                     args[1].immediate(),
 123                     args[2].immediate(),
 124                     llresult,
 125                 );
 126                 return;
 127             }
 128             sym::breakpoint => {
 129                 let llfn = self.get_intrinsic(&("llvm.debugtrap"));
 130                 self.call(llfn, &[], None)
 131             }
 132             sym::va_copy => {
 133                 let intrinsic = self.cx().get_intrinsic(&("llvm.va_copy"));
 134                 self.call(intrinsic, &[args[0].immediate(), args[1].immediate()], None)
 135             }
 136             sym::va_arg => {
 137                 match fn_abi.ret.layout.abi {
 138                     abi::Abi::Scalar(ref scalar) => {
 139                         match scalar.value {
 140                             Primitive::Int(..) => {
 141                                 if self.cx().size_of(ret_ty).bytes() < 4 {
 142                                     // `va_arg` should not be called on a integer type
 143                                     // less than 4 bytes in length. If it is, promote
 144                                     // the integer to a `i32` and truncate the result
 145                                     // back to the smaller type.
 146                                     let promoted_result = emit_va_arg(self, args[0], tcx.types.i32);
 147                                     self.trunc(promoted_result, llret_ty)
 148                                 } else {
 149                                     emit_va_arg(self, args[0], ret_ty)
 150                                 }
 151                             }
 152                             Primitive::F64 | Primitive::Pointer => {
 153                                 emit_va_arg(self, args[0], ret_ty)
 154                             }
 155                             // `va_arg` should never be used with the return type f32.
 156                             Primitive::F32 => bug!("the va_arg intrinsic does not work with `f32`"),
 157                         }
 158                     }
 159                     _ => bug!("the va_arg intrinsic does not work with non-scalar types"),
 160                 }
 161             }
 162
 163             sym::volatile_load | sym::unaligned_volatile_load => {
 164                 let tp_ty = substs.type_at(0);
 165                 let ptr = args[0].immediate();
 166                 let load = if let PassMode::Cast(ty) = fn_abi.ret.mode {
 167                     let llty = ty.llvm_type(self);
 168                     let ptr = self.pointercast(ptr, self.type_ptr_to(llty));
 169                     self.volatile_load(llty, ptr)
 170                 } else {
 171                     self.volatile_load(self.layout_of(tp_ty).llvm_type(self), ptr)
 172                 };
 173                 let align = if name == sym::unaligned_volatile_load {
 174                     1
 175                 } else {
 176                     self.align_of(tp_ty).bytes() as u32
 177                 };
 178                 unsafe {
 179                     llvm::LLVMSetAlignment(load, align);
 180                 }
 181                 self.to_immediate(load, self.layout_of(tp_ty))
 182             }
 183             sym::volatile_store => {
 184                 let dst = args[0].deref(self.cx());
 185                 args[1].val.volatile_store(self, dst);
 186                 return;
 187             }
 188             sym::unaligned_volatile_store => {
 189                 let dst = args[0].deref(self.cx());
 190                 args[1].val.unaligned_volatile_store(self, dst);
 191                 return;
 192             }
 193             sym::prefetch_read_data
 194             | sym::prefetch_write_data
 195             | sym::prefetch_read_instruction
 196             | sym::prefetch_write_instruction => {
 197                 let expect = self.get_intrinsic(&("llvm.prefetch"));
 198                 let (rw, cache_type) = match name {
 199                     sym::prefetch_read_data => (0, 1),
 200                     sym::prefetch_write_data => (1, 1),
 201                     sym::prefetch_read_instruction => (0, 0),
 202                     sym::prefetch_write_instruction => (1, 0),
 203                     _ => bug!(),
 204                 };
 205                 self.call(
 206                     expect,
 207                     &[
 208                         args[0].immediate(),
 209                         self.const_i32(rw),
 210                         args[1].immediate(),
 211                         self.const_i32(cache_type),
 212                     ],
 213                     None,
 214                 )
 215             }
 216             sym::ctlz
 217             | sym::ctlz_nonzero
 218             | sym::cttz
 219             | sym::cttz_nonzero
 220             | sym::ctpop
 221             | sym::bswap
 222             | sym::bitreverse
 223             | sym::rotate_left
 224             | sym::rotate_right
 225             | sym::saturating_add
 226             | sym::saturating_sub => {
 227                 let ty = arg_tys[0];
 228                 match int_type_width_signed(ty, self) {
 229                     Some((width, signed)) => match name {
 230                         sym::ctlz | sym::cttz => {
 231                             let y = self.const_bool(false);
 232                             let llfn = self.get_intrinsic(&format!("llvm.{}.i{}", name, width));
 233                             self.call(llfn, &[args[0].immediate(), y], None)
 234                         }
 235                         sym::ctlz_nonzero | sym::cttz_nonzero => {
 236                             let y = self.const_bool(true);
 237                             let llvm_name = &format!("llvm.{}.i{}", &name_str[..4], width);
 238                             let llfn = self.get_intrinsic(llvm_name);
 239                             self.call(llfn, &[args[0].immediate(), y], None)
 240                         }
 241                         sym::ctpop => self.call(
 242                             self.get_intrinsic(&format!("llvm.ctpop.i{}", width)),
 243                             &[args[0].immediate()],
 244                             None,
 245                         ),
 246                         sym::bswap => {
 247                             if width == 8 {
 248                                 args[0].immediate() // byte swap a u8/i8 is just a no-op
 249                             } else {
 250                                 self.call(
 251                                     self.get_intrinsic(&format!("llvm.bswap.i{}", width)),
 252                                     &[args[0].immediate()],
 253                                     None,
 254                                 )
 255                             }
 256                         }
 257                         sym::bitreverse => self.call(
 258                             self.get_intrinsic(&format!("llvm.bitreverse.i{}", width)),
 259                             &[args[0].immediate()],
 260                             None,
 261                         ),
 262                         sym::rotate_left | sym::rotate_right => {
 263                             let is_left = name == sym::rotate_left;
 264                             let val = args[0].immediate();
 265                             let raw_shift = args[1].immediate();
 266                             // rotate = funnel shift with first two args the same
 267                             let llvm_name =
 268                                 &format!("llvm.fsh{}.i{}", if is_left { 'l' } else { 'r' }, width);
 269                             let llfn = self.get_intrinsic(llvm_name);
 270                             self.call(llfn, &[val, val, raw_shift], None)
 271                         }
 272                         sym::saturating_add | sym::saturating_sub => {
 273                             let is_add = name == sym::saturating_add;
 274                             let lhs = args[0].immediate();
 275                             let rhs = args[1].immediate();
 276                             let llvm_name = &format!(
 277                                 "llvm.{}{}.sat.i{}",
 278                                 if signed { 's' } else { 'u' },
 279                                 if is_add { "add" } else { "sub" },
 280                                 width
 281                             );
 282                             let llfn = self.get_intrinsic(llvm_name);
 283                             self.call(llfn, &[lhs, rhs], None)
 284                         }
 285                         _ => bug!(),
 286                     },
 287                     None => {
 288                         span_invalid_monomorphization_error(
 289                             tcx.sess,
 290                             span,
 291                             &format!(
 292                                 "invalid monomorphization of `{}` intrinsic: \
 293                                       expected basic integer type, found `{}`",
 294                                 name, ty
 295                             ),
 296                         );
 297                         return;
 298                     }
 299                 }
 300             }
 301
 302             sym::raw_eq => {
 303                 use abi::Abi::*;
 304                 let tp_ty = substs.type_at(0);
 305                 let layout = self.layout_of(tp_ty).layout;
 306                 let use_integer_compare = match layout.abi {
 307                     Scalar(_) | ScalarPair(_, _) => true,
 308                     Uninhabited | Vector { .. } => false,
 309                     Aggregate { .. } => {
 310                         // For rusty ABIs, small aggregates are actually passed
 311                         // as `RegKind::Integer` (see `FnAbi::adjust_for_abi`),
 312                         // so we re-use that same threshold here.
 313                         layout.size <= self.data_layout().pointer_size * 2
 314                     }
 315                 };
 316
 317                 let a = args[0].immediate();
 318                 let b = args[1].immediate();
 319                 if layout.size.bytes() == 0 {
 320                     self.const_bool(true)
 321                 } else if use_integer_compare {
 322                     let integer_ty = self.type_ix(layout.size.bits());
 323                     let ptr_ty = self.type_ptr_to(integer_ty);
 324                     let a_ptr = self.bitcast(a, ptr_ty);
 325                     let a_val = self.load(integer_ty, a_ptr, layout.align.abi);
 326                     let b_ptr = self.bitcast(b, ptr_ty);
 327                     let b_val = self.load(integer_ty, b_ptr, layout.align.abi);
 328                     self.icmp(IntPredicate::IntEQ, a_val, b_val)
 329                 } else {
 330                     let i8p_ty = self.type_i8p();
 331                     let a_ptr = self.bitcast(a, i8p_ty);
 332                     let b_ptr = self.bitcast(b, i8p_ty);
 333                     let n = self.const_usize(layout.size.bytes());
 334                     let llfn = self.get_intrinsic("memcmp");
 335                     let cmp = self.call(llfn, &[a_ptr, b_ptr, n], None);
 336                     self.icmp(IntPredicate::IntEQ, cmp, self.const_i32(0))
 337                 }
 338             }
 339
 340             _ if name_str.starts_with("simd_") => {
 341                 match generic_simd_intrinsic(self, name, callee_ty, args, ret_ty, llret_ty, span) {
 342                     Ok(llval) => llval,
 343                     Err(()) => return,
 344                 }
 345             }
 346
 347             _ => bug!("unknown intrinsic '{}'", name),
 348         };
 349
 350         if !fn_abi.ret.is_ignore() {
 351             if let PassMode::Cast(ty) = fn_abi.ret.mode {
 352                 let ptr_llty = self.type_ptr_to(ty.llvm_type(self));
 353                 let ptr = self.pointercast(result.llval, ptr_llty);
 354                 self.store(llval, ptr, result.align);
 355             } else {
 356                 OperandRef::from_immediate_or_packed_pair(self, llval, result.layout)
 357                     .val
 358                     .store(self, result);
 359             }
 360         }
 361     }
 362
 363     fn abort(&mut self) {
 364         let fnname = self.get_intrinsic(&("llvm.trap"));
 365         self.call(fnname, &[], None);
 366     }
 367
 368     fn assume(&mut self, val: Self::Value) {
 369         let assume_intrinsic = self.get_intrinsic("llvm.assume");
 370         self.call(assume_intrinsic, &[val], None);
 371     }
 372
 373     fn expect(&mut self, cond: Self::Value, expected: bool) -> Self::Value {
 374         let expect = self.get_intrinsic(&"llvm.expect.i1");
 375         self.call(expect, &[cond, self.const_bool(expected)], None)
 376     }
 377
 378     fn sideeffect(&mut self) {
 379         // This kind of check would make a ton of sense in the caller, but currently the only
 380         // caller of this function is in `rustc_codegen_ssa`, which is agnostic to whether LLVM
 381         // codegen backend being used, and so is unable to check the LLVM version.
 382         if unsafe { llvm::LLVMRustVersionMajor() } < 12 {
 383             let fnname = self.get_intrinsic(&("llvm.sideeffect"));
 384             self.call(fnname, &[], None);
 385         }
 386     }
 387
 388     fn va_start(&mut self, va_list: &'ll Value) -> &'ll Value {
 389         let intrinsic = self.cx().get_intrinsic("llvm.va_start");
 390         self.call(intrinsic, &[va_list], None)
 391     }
 392
 393     fn va_end(&mut self, va_list: &'ll Value) -> &'ll Value {
 394         let intrinsic = self.cx().get_intrinsic("llvm.va_end");
 395         self.call(intrinsic, &[va_list], None)
 396     }
 397 }
 398
 399 fn try_intrinsic(
 400     bx: &mut Builder<'a, 'll, 'tcx>,
 401     try_func: &'ll Value,
 402     data: &'ll Value,
 403     catch_func: &'ll Value,
 404     dest: &'ll Value,
 405 ) {
 406     if bx.sess().panic_strategy() == PanicStrategy::Abort {
 407         bx.call(try_func, &[data], None);
 408         // Return 0 unconditionally from the intrinsic call;
 409         // we can never unwind.
 410         let ret_align = bx.tcx().data_layout.i32_align.abi;
 411         bx.store(bx.const_i32(0), dest, ret_align);
 412     } else if wants_msvc_seh(bx.sess()) {
 413         codegen_msvc_try(bx, try_func, data, catch_func, dest);
 414     } else if bx.sess().target.is_like_emscripten {
 415         codegen_emcc_try(bx, try_func, data, catch_func, dest);
 416     } else {
 417         codegen_gnu_try(bx, try_func, data, catch_func, dest);
 418     }
 419 }
 420
 421 // MSVC's definition of the `rust_try` function.
 422 //
 423 // This implementation uses the new exception handling instructions in LLVM
 424 // which have support in LLVM for SEH on MSVC targets. Although these
 425 // instructions are meant to work for all targets, as of the time of this
 426 // writing, however, LLVM does not recommend the usage of these new instructions
 427 // as the old ones are still more optimized.
 428 fn codegen_msvc_try(
 429     bx: &mut Builder<'a, 'll, 'tcx>,
 430     try_func: &'ll Value,
 431     data: &'ll Value,
 432     catch_func: &'ll Value,
 433     dest: &'ll Value,
 434 ) {
 435     let llfn = get_rust_try_fn(bx, &mut |mut bx| {
 436         bx.set_personality_fn(bx.eh_personality());
 437
 438         let mut normal = bx.build_sibling_block("normal");
 439         let mut catchswitch = bx.build_sibling_block("catchswitch");
 440         let mut catchpad_rust = bx.build_sibling_block("catchpad_rust");
 441         let mut catchpad_foreign = bx.build_sibling_block("catchpad_foreign");
 442         let mut caught = bx.build_sibling_block("caught");
 443
 444         let try_func = llvm::get_param(bx.llfn(), 0);
 445         let data = llvm::get_param(bx.llfn(), 1);
 446         let catch_func = llvm::get_param(bx.llfn(), 2);
 447
 448         // We're generating an IR snippet that looks like:
 449         //
 450         //   declare i32 @rust_try(%try_func, %data, %catch_func) {
 451         //      %slot = alloca i8*
 452         //      invoke %try_func(%data) to label %normal unwind label %catchswitch
 453         //
 454         //   normal:
 455         //      ret i32 0
 456         //
 457         //   catchswitch:
 458         //      %cs = catchswitch within none [%catchpad_rust, %catchpad_foreign] unwind to caller
 459         //
 460         //   catchpad_rust:
 461         //      %tok = catchpad within %cs [%type_descriptor, 8, %slot]
 462         //      %ptr = load %slot
 463         //      call %catch_func(%data, %ptr)
 464         //      catchret from %tok to label %caught
 465         //
 466         //   catchpad_foreign:
 467         //      %tok = catchpad within %cs [null, 64, null]
 468         //      call %catch_func(%data, null)
 469         //      catchret from %tok to label %caught
 470         //
 471         //   caught:
 472         //      ret i32 1
 473         //   }
 474         //
 475         // This structure follows the basic usage of throw/try/catch in LLVM.
 476         // For example, compile this C++ snippet to see what LLVM generates:
 477         //
 478         //      struct rust_panic {
 479         //          rust_panic(const rust_panic&);
 480         //          ~rust_panic();
 481         //
 482         //          void* x[2];
 483         //      };
 484         //
 485         //      int __rust_try(
 486         //          void (*try_func)(void*),
 487         //          void *data,
 488         //          void (*catch_func)(void*, void*) noexcept
 489         //      ) {
 490         //          try {
 491         //              try_func(data);
 492         //              return 0;
 493         //          } catch(rust_panic& a) {
 494         //              catch_func(data, &a);
 495         //              return 1;
 496         //          } catch(...) {
 497         //              catch_func(data, NULL);
 498         //              return 1;
 499         //          }
 500         //      }
 501         //
 502         // More information can be found in libstd's seh.rs implementation.
 503         let ptr_align = bx.tcx().data_layout.pointer_align.abi;
 504         let slot = bx.alloca(bx.type_i8p(), ptr_align);
 505         bx.invoke(try_func, &[data], normal.llbb(), catchswitch.llbb(), None);
 506
 507         normal.ret(bx.const_i32(0));
 508
 509         let cs = catchswitch.catch_switch(None, None, 2);
 510         catchswitch.add_handler(cs, catchpad_rust.llbb());
 511         catchswitch.add_handler(cs, catchpad_foreign.llbb());
 512
 513         // We can't use the TypeDescriptor defined in libpanic_unwind because it
 514         // might be in another DLL and the SEH encoding only supports specifying
 515         // a TypeDescriptor from the current module.
 516         //
 517         // However this isn't an issue since the MSVC runtime uses string
 518         // comparison on the type name to match TypeDescriptors rather than
 519         // pointer equality.
 520         //
 521         // So instead we generate a new TypeDescriptor in each module that uses
 522         // `try` and let the linker merge duplicate definitions in the same
 523         // module.
 524         //
 525         // When modifying, make sure that the type_name string exactly matches
 526         // the one used in src/libpanic_unwind/seh.rs.
 527         let type_info_vtable = bx.declare_global("??_7type_info@@6B@", bx.type_i8p());
 528         let type_name = bx.const_bytes(b"rust_panic\0");
 529         let type_info =
 530             bx.const_struct(&[type_info_vtable, bx.const_null(bx.type_i8p()), type_name], false);
 531         let tydesc = bx.declare_global("__rust_panic_type_info", bx.val_ty(type_info));
 532         unsafe {
 533             llvm::LLVMRustSetLinkage(tydesc, llvm::Linkage::LinkOnceODRLinkage);
 534             llvm::SetUniqueComdat(bx.llmod, tydesc);
 535             llvm::LLVMSetInitializer(tydesc, type_info);
 536         }
 537
 538         // The flag value of 8 indicates that we are catching the exception by
 539         // reference instead of by value. We can't use catch by value because
 540         // that requires copying the exception object, which we don't support
 541         // since our exception object effectively contains a Box.
 542         //
 543         // Source: MicrosoftCXXABI::getAddrOfCXXCatchHandlerType in clang
 544         let flags = bx.const_i32(8);
 545         let funclet = catchpad_rust.catch_pad(cs, &[tydesc, flags, slot]);
 546         let ptr = catchpad_rust.load(bx.type_i8p(), slot, ptr_align);
 547         catchpad_rust.call(catch_func, &[data, ptr], Some(&funclet));
 548         catchpad_rust.catch_ret(&funclet, caught.llbb());
 549
 550         // The flag value of 64 indicates a "catch-all".
 551         let flags = bx.const_i32(64);
 552         let null = bx.const_null(bx.type_i8p());
 553         let funclet = catchpad_foreign.catch_pad(cs, &[null, flags, null]);
 554         catchpad_foreign.call(catch_func, &[data, null], Some(&funclet));
 555         catchpad_foreign.catch_ret(&funclet, caught.llbb());
 556
 557         caught.ret(bx.const_i32(1));
 558     });
 559
 560     // Note that no invoke is used here because by definition this function
 561     // can't panic (that's what it's catching).
 562     let ret = bx.call(llfn, &[try_func, data, catch_func], None);
 563     let i32_align = bx.tcx().data_layout.i32_align.abi;
 564     bx.store(ret, dest, i32_align);
 565 }
 566
 567 // Definition of the standard `try` function for Rust using the GNU-like model
 568 // of exceptions (e.g., the normal semantics of LLVM's `landingpad` and `invoke`
 569 // instructions).
 570 //
 571 // This codegen is a little surprising because we always call a shim
 572 // function instead of inlining the call to `invoke` manually here. This is done
 573 // because in LLVM we're only allowed to have one personality per function
 574 // definition. The call to the `try` intrinsic is being inlined into the
 575 // function calling it, and that function may already have other personality
 576 // functions in play. By calling a shim we're guaranteed that our shim will have
 577 // the right personality function.
 578 fn codegen_gnu_try(
 579     bx: &mut Builder<'a, 'll, 'tcx>,
 580     try_func: &'ll Value,
 581     data: &'ll Value,
 582     catch_func: &'ll Value,
 583     dest: &'ll Value,
 584 ) {
 585     let llfn = get_rust_try_fn(bx, &mut |mut bx| {
 586         // Codegens the shims described above:
 587         //
 588         //   bx:
 589         //      invoke %try_func(%data) normal %normal unwind %catch
 590         //
 591         //   normal:
 592         //      ret 0
 593         //
 594         //   catch:
 595         //      (%ptr, _) = landingpad
 596         //      call %catch_func(%data, %ptr)
 597         //      ret 1
 598         let mut then = bx.build_sibling_block("then");
 599         let mut catch = bx.build_sibling_block("catch");
 600
 601         let try_func = llvm::get_param(bx.llfn(), 0);
 602         let data = llvm::get_param(bx.llfn(), 1);
 603         let catch_func = llvm::get_param(bx.llfn(), 2);
 604         bx.invoke(try_func, &[data], then.llbb(), catch.llbb(), None);
 605         then.ret(bx.const_i32(0));
 606
 607         // Type indicator for the exception being thrown.
 608         //
 609         // The first value in this tuple is a pointer to the exception object
 610         // being thrown.  The second value is a "selector" indicating which of
 611         // the landing pad clauses the exception's type had been matched to.
 612         // rust_try ignores the selector.
 613         let lpad_ty = bx.type_struct(&[bx.type_i8p(), bx.type_i32()], false);
 614         let vals = catch.landing_pad(lpad_ty, bx.eh_personality(), 1);
 615         let tydesc = bx.const_null(bx.type_i8p());
 616         catch.add_clause(vals, tydesc);
 617         let ptr = catch.extract_value(vals, 0);
 618         catch.call(catch_func, &[data, ptr], None);
 619         catch.ret(bx.const_i32(1));
 620     });
 621
 622     // Note that no invoke is used here because by definition this function
 623     // can't panic (that's what it's catching).
 624     let ret = bx.call(llfn, &[try_func, data, catch_func], None);
 625     let i32_align = bx.tcx().data_layout.i32_align.abi;
 626     bx.store(ret, dest, i32_align);
 627 }
 628
 629 // Variant of codegen_gnu_try used for emscripten where Rust panics are
 630 // implemented using C++ exceptions. Here we use exceptions of a specific type
 631 // (`struct rust_panic`) to represent Rust panics.
 632 fn codegen_emcc_try(
 633     bx: &mut Builder<'a, 'll, 'tcx>,
 634     try_func: &'ll Value,
 635     data: &'ll Value,
 636     catch_func: &'ll Value,
 637     dest: &'ll Value,
 638 ) {
 639     let llfn = get_rust_try_fn(bx, &mut |mut bx| {
 640         // Codegens the shims described above:
 641         //
 642         //   bx:
 643         //      invoke %try_func(%data) normal %normal unwind %catch
 644         //
 645         //   normal:
 646         //      ret 0
 647         //
 648         //   catch:
 649         //      (%ptr, %selector) = landingpad
 650         //      %rust_typeid = @llvm.eh.typeid.for(@_ZTI10rust_panic)
 651         //      %is_rust_panic = %selector == %rust_typeid
 652         //      %catch_data = alloca { i8*, i8 }
 653         //      %catch_data[0] = %ptr
 654         //      %catch_data[1] = %is_rust_panic
 655         //      call %catch_func(%data, %catch_data)
 656         //      ret 1
 657         let mut then = bx.build_sibling_block("then");
 658         let mut catch = bx.build_sibling_block("catch");
 659
 660         let try_func = llvm::get_param(bx.llfn(), 0);
 661         let data = llvm::get_param(bx.llfn(), 1);
 662         let catch_func = llvm::get_param(bx.llfn(), 2);
 663         bx.invoke(try_func, &[data], then.llbb(), catch.llbb(), None);
 664         then.ret(bx.const_i32(0));
 665
 666         // Type indicator for the exception being thrown.
 667         //
 668         // The first value in this tuple is a pointer to the exception object
 669         // being thrown.  The second value is a "selector" indicating which of
 670         // the landing pad clauses the exception's type had been matched to.
 671         let tydesc = bx.eh_catch_typeinfo();
 672         let lpad_ty = bx.type_struct(&[bx.type_i8p(), bx.type_i32()], false);
 673         let vals = catch.landing_pad(lpad_ty, bx.eh_personality(), 2);
 674         catch.add_clause(vals, tydesc);
 675         catch.add_clause(vals, bx.const_null(bx.type_i8p()));
 676         let ptr = catch.extract_value(vals, 0);
 677         let selector = catch.extract_value(vals, 1);
 678
 679         // Check if the typeid we got is the one for a Rust panic.
 680         let llvm_eh_typeid_for = bx.get_intrinsic("llvm.eh.typeid.for");
 681         let rust_typeid = catch.call(llvm_eh_typeid_for, &[tydesc], None);
 682         let is_rust_panic = catch.icmp(IntPredicate::IntEQ, selector, rust_typeid);
 683         let is_rust_panic = catch.zext(is_rust_panic, bx.type_bool());
 684
 685         // We need to pass two values to catch_func (ptr and is_rust_panic), so
 686         // create an alloca and pass a pointer to that.
 687         let ptr_align = bx.tcx().data_layout.pointer_align.abi;
 688         let i8_align = bx.tcx().data_layout.i8_align.abi;
 689         let catch_data =
 690             catch.alloca(bx.type_struct(&[bx.type_i8p(), bx.type_bool()], false), ptr_align);
 691         let catch_data_0 = catch.inbounds_gep(catch_data, &[bx.const_usize(0), bx.const_usize(0)]);
 692         catch.store(ptr, catch_data_0, ptr_align);
 693         let catch_data_1 = catch.inbounds_gep(catch_data, &[bx.const_usize(0), bx.const_usize(1)]);
 694         catch.store(is_rust_panic, catch_data_1, i8_align);
 695         let catch_data = catch.bitcast(catch_data, bx.type_i8p());
 696
 697         catch.call(catch_func, &[data, catch_data], None);
 698         catch.ret(bx.const_i32(1));
 699     });
 700
 701     // Note that no invoke is used here because by definition this function
 702     // can't panic (that's what it's catching).
 703     let ret = bx.call(llfn, &[try_func, data, catch_func], None);
 704     let i32_align = bx.tcx().data_layout.i32_align.abi;
 705     bx.store(ret, dest, i32_align);
 706 }
 707
 708 // Helper function to give a Block to a closure to codegen a shim function.
 709 // This is currently primarily used for the `try` intrinsic functions above.
 710 fn gen_fn<'ll, 'tcx>(
 711     cx: &CodegenCx<'ll, 'tcx>,
 712     name: &str,
 713     rust_fn_sig: ty::PolyFnSig<'tcx>,
 714     codegen: &mut dyn FnMut(Builder<'_, 'll, 'tcx>),
 715 ) -> &'ll Value {
 716     let fn_abi = FnAbi::of_fn_ptr(cx, rust_fn_sig, &[]);
 717     let llfn = cx.declare_fn(name, &fn_abi);
 718     cx.set_frame_pointer_type(llfn);
 719     cx.apply_target_cpu_attr(llfn);
 720     // FIXME(eddyb) find a nicer way to do this.
 721     unsafe { llvm::LLVMRustSetLinkage(llfn, llvm::Linkage::InternalLinkage) };
 722     let llbb = Builder::append_block(cx, llfn, "entry-block");
 723     let bx = Builder::build(cx, llbb);
 724     codegen(bx);
 725     llfn
 726 }
 727
 728 // Helper function used to get a handle to the `__rust_try` function used to
 729 // catch exceptions.
 730 //
 731 // This function is only generated once and is then cached.
 732 fn get_rust_try_fn<'ll, 'tcx>(
 733     cx: &CodegenCx<'ll, 'tcx>,
 734     codegen: &mut dyn FnMut(Builder<'_, 'll, 'tcx>),
 735 ) -> &'ll Value {
 736     if let Some(llfn) = cx.rust_try_fn.get() {
 737         return llfn;
 738     }
 739
 740     // Define the type up front for the signature of the rust_try function.
 741     let tcx = cx.tcx;
 742     let i8p = tcx.mk_mut_ptr(tcx.types.i8);
 743     // `unsafe fn(*mut i8) -> ()`
 744     let try_fn_ty = tcx.mk_fn_ptr(ty::Binder::dummy(tcx.mk_fn_sig(
 745         iter::once(i8p),
 746         tcx.mk_unit(),
 747         false,
 748         hir::Unsafety::Unsafe,
 749         Abi::Rust,
 750     )));
 751     // `unsafe fn(*mut i8, *mut i8) -> ()`
 752     let catch_fn_ty = tcx.mk_fn_ptr(ty::Binder::dummy(tcx.mk_fn_sig(
 753         [i8p, i8p].iter().cloned(),
 754         tcx.mk_unit(),
 755         false,
 756         hir::Unsafety::Unsafe,
 757         Abi::Rust,
 758     )));
 759     // `unsafe fn(unsafe fn(*mut i8) -> (), *mut i8, unsafe fn(*mut i8, *mut i8) -> ()) -> i32`
 760     let rust_fn_sig = ty::Binder::dummy(cx.tcx.mk_fn_sig(
 761         vec![try_fn_ty, i8p, catch_fn_ty].into_iter(),
 762         tcx.types.i32,
 763         false,
 764         hir::Unsafety::Unsafe,
 765         Abi::Rust,
 766     ));
 767     let rust_try = gen_fn(cx, "__rust_try", rust_fn_sig, codegen);
 768     cx.rust_try_fn.set(Some(rust_try));
 769     rust_try
 770 }
 771
 772 fn generic_simd_intrinsic(
 773     bx: &mut Builder<'a, 'll, 'tcx>,
 774     name: Symbol,
 775     callee_ty: Ty<'tcx>,
 776     args: &[OperandRef<'tcx, &'ll Value>],
 777     ret_ty: Ty<'tcx>,
 778     llret_ty: &'ll Type,
 779     span: Span,
 780 ) -> Result<&'ll Value, ()> {
 781     // macros for error handling:
 782     macro_rules! emit_error {
 783         ($msg: tt) => {
 784             emit_error!($msg, )
 785         };
 786         ($msg: tt, $($fmt: tt)*) => {
 787             span_invalid_monomorphization_error(
 788                 bx.sess(), span,
 789                 &format!(concat!("invalid monomorphization of `{}` intrinsic: ", $msg),
 790                          name, $($fmt)*));
 791         }
 792     }
 793
 794     macro_rules! return_error {
 795         ($($fmt: tt)*) => {
 796             {
 797                 emit_error!($($fmt)*);
 798                 return Err(());
 799             }
 800         }
 801     }
 802
 803     macro_rules! require {
 804         ($cond: expr, $($fmt: tt)*) => {
 805             if !$cond {
 806                 return_error!($($fmt)*);
 807             }
 808         };
 809     }
 810
 811     macro_rules! require_simd {
 812         ($ty: expr, $position: expr) => {
 813             require!($ty.is_simd(), "expected SIMD {} type, found non-SIMD `{}`", $position, $ty)
 814         };
 815     }
 816
 817     let tcx = bx.tcx();
 818     let sig =
 819         tcx.normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), callee_ty.fn_sig(tcx));
 820     let arg_tys = sig.inputs();
 821     let name_str = &*name.as_str();
 822
 823     if name == sym::simd_select_bitmask {
 824         let in_ty = arg_tys[0];
 825         let m_len = match in_ty.kind() {
 826             // Note that this `.unwrap()` crashes for isize/usize, that's sort
 827             // of intentional as there's not currently a use case for that.
 828             ty::Int(i) => i.bit_width().unwrap(),
 829             ty::Uint(i) => i.bit_width().unwrap(),
 830             _ => return_error!("`{}` is not an integral type", in_ty),
 831         };
 832         require_simd!(arg_tys[1], "argument");
 833         let (v_len, _) = arg_tys[1].simd_size_and_type(bx.tcx());
 834         require!(
 835             // Allow masks for vectors with fewer than 8 elements to be
 836             // represented with a u8 or i8.
 837             m_len == v_len || (m_len == 8 && v_len < 8),
 838             "mismatched lengths: mask length `{}` != other vector length `{}`",
 839             m_len,
 840             v_len
 841         );
 842         let i1 = bx.type_i1();
 843         let im = bx.type_ix(v_len);
 844         let i1xn = bx.type_vector(i1, v_len);
 845         let m_im = bx.trunc(args[0].immediate(), im);
 846         let m_i1s = bx.bitcast(m_im, i1xn);
 847         return Ok(bx.select(m_i1s, args[1].immediate(), args[2].immediate()));
 848     }
 849
 850     // every intrinsic below takes a SIMD vector as its first argument
 851     require_simd!(arg_tys[0], "input");
 852     let in_ty = arg_tys[0];
 853
 854     let comparison = match name {
 855         sym::simd_eq => Some(hir::BinOpKind::Eq),
 856         sym::simd_ne => Some(hir::BinOpKind::Ne),
 857         sym::simd_lt => Some(hir::BinOpKind::Lt),
 858         sym::simd_le => Some(hir::BinOpKind::Le),
 859         sym::simd_gt => Some(hir::BinOpKind::Gt),
 860         sym::simd_ge => Some(hir::BinOpKind::Ge),
 861         _ => None,
 862     };
 863
 864     let (in_len, in_elem) = arg_tys[0].simd_size_and_type(bx.tcx());
 865     if let Some(cmp_op) = comparison {
 866         require_simd!(ret_ty, "return");
 867
 868         let (out_len, out_ty) = ret_ty.simd_size_and_type(bx.tcx());
 869         require!(
 870             in_len == out_len,
 871             "expected return type with length {} (same as input type `{}`), \
 872              found `{}` with length {}",
 873             in_len,
 874             in_ty,
 875             ret_ty,
 876             out_len
 877         );
 878         require!(
 879             bx.type_kind(bx.element_type(llret_ty)) == TypeKind::Integer,
 880             "expected return type with integer elements, found `{}` with non-integer `{}`",
 881             ret_ty,
 882             out_ty
 883         );
 884
 885         return Ok(compare_simd_types(
 886             bx,
 887             args[0].immediate(),
 888             args[1].immediate(),
 889             in_elem,
 890             llret_ty,
 891             cmp_op,
 892         ));
 893     }
 894
 895     if let Some(stripped) = name_str.strip_prefix("simd_shuffle") {
 896         let n: u64 = stripped.parse().unwrap_or_else(|_| {
 897             span_bug!(span, "bad `simd_shuffle` instruction only caught in codegen?")
 898         });
 899
 900         require_simd!(ret_ty, "return");
 901
 902         let (out_len, out_ty) = ret_ty.simd_size_and_type(bx.tcx());
 903         require!(
 904             out_len == n,
 905             "expected return type of length {}, found `{}` with length {}",
 906             n,
 907             ret_ty,
 908             out_len
 909         );
 910         require!(
 911             in_elem == out_ty,
 912             "expected return element type `{}` (element of input `{}`), \
 913              found `{}` with element type `{}`",
 914             in_elem,
 915             in_ty,
 916             ret_ty,
 917             out_ty
 918         );
 919
 920         let total_len = u128::from(in_len) * 2;
 921
 922         let vector = args[2].immediate();
 923
 924         let indices: Option<Vec<_>> = (0..n)
 925             .map(|i| {
 926                 let arg_idx = i;
 927                 let val = bx.const_get_elt(vector, i as u64);
 928                 match bx.const_to_opt_u128(val, true) {
 929                     None => {
 930                         emit_error!("shuffle index #{} is not a constant", arg_idx);
 931                         None
 932                     }
 933                     Some(idx) if idx >= total_len => {
 934                         emit_error!(
 935                             "shuffle index #{} is out of bounds (limit {})",
 936                             arg_idx,
 937                             total_len
 938                         );
 939                         None
 940                     }
 941                     Some(idx) => Some(bx.const_i32(idx as i32)),
 942                 }
 943             })
 944             .collect();
 945         let indices = match indices {
 946             Some(i) => i,
 947             None => return Ok(bx.const_null(llret_ty)),
 948         };
 949
 950         return Ok(bx.shuffle_vector(
 951             args[0].immediate(),
 952             args[1].immediate(),
 953             bx.const_vector(&indices),
 954         ));
 955     }
 956
 957     if name == sym::simd_insert {
 958         require!(
 959             in_elem == arg_tys[2],
 960             "expected inserted type `{}` (element of input `{}`), found `{}`",
 961             in_elem,
 962             in_ty,
 963             arg_tys[2]
 964         );
 965         return Ok(bx.insert_element(
 966             args[0].immediate(),
 967             args[2].immediate(),
 968             args[1].immediate(),
 969         ));
 970     }
 971     if name == sym::simd_extract {
 972         require!(
 973             ret_ty == in_elem,
 974             "expected return type `{}` (element of input `{}`), found `{}`",
 975             in_elem,
 976             in_ty,
 977             ret_ty
 978         );
 979         return Ok(bx.extract_element(args[0].immediate(), args[1].immediate()));
 980     }
 981
 982     if name == sym::simd_select {
 983         let m_elem_ty = in_elem;
 984         let m_len = in_len;
 985         require_simd!(arg_tys[1], "argument");
 986         let (v_len, _) = arg_tys[1].simd_size_and_type(bx.tcx());
 987         require!(
 988             m_len == v_len,
 989             "mismatched lengths: mask length `{}` != other vector length `{}`",
 990             m_len,
 991             v_len
 992         );
 993         match m_elem_ty.kind() {
 994             ty::Int(_) => {}
 995             _ => return_error!("mask element type is `{}`, expected `i_`", m_elem_ty),
 996         }
 997         // truncate the mask to a vector of i1s
 998         let i1 = bx.type_i1();
 999         let i1xn = bx.type_vector(i1, m_len as u64);
1000         let m_i1s = bx.trunc(args[0].immediate(), i1xn);
1001         return Ok(bx.select(m_i1s, args[1].immediate(), args[2].immediate()));
1002     }
1003
1004     if name == sym::simd_bitmask {
1005         // The `fn simd_bitmask(vector) -> unsigned integer` intrinsic takes a
1006         // vector mask and returns an unsigned integer containing the most
1007         // significant bit (MSB) of each lane.
1008
1009         // If the vector has less than 8 lanes, an u8 is returned with zeroed
1010         // trailing bits.
1011         let expected_int_bits = in_len.max(8);
1012         match ret_ty.kind() {
1013             ty::Uint(i) if i.bit_width() == Some(expected_int_bits) => (),
1014             _ => return_error!("bitmask `{}`, expected `u{}`", ret_ty, expected_int_bits),
1015         }
1016
1017         // Integer vector <i{in_bitwidth} x in_len>:
1018         let (i_xn, in_elem_bitwidth) = match in_elem.kind() {
1019             ty::Int(i) => (
1020                 args[0].immediate(),
1021                 i.bit_width().unwrap_or_else(|| bx.data_layout().pointer_size.bits()),
1022             ),
1023             ty::Uint(i) => (
1024                 args[0].immediate(),
1025                 i.bit_width().unwrap_or_else(|| bx.data_layout().pointer_size.bits()),
1026             ),
1027             _ => return_error!(
1028                 "vector argument `{}`'s element type `{}`, expected integer element type",
1029                 in_ty,
1030                 in_elem
1031             ),
1032         };
1033
1034         // Shift the MSB to the right by "in_elem_bitwidth - 1" into the first bit position.
1035         let shift_indices =
1036             vec![
1037                 bx.cx.const_int(bx.type_ix(in_elem_bitwidth), (in_elem_bitwidth - 1) as _);
1038                 in_len as _
1039             ];
1040         let i_xn_msb = bx.lshr(i_xn, bx.const_vector(shift_indices.as_slice()));
1041         // Truncate vector to an <i1 x N>
1042         let i1xn = bx.trunc(i_xn_msb, bx.type_vector(bx.type_i1(), in_len));
1043         // Bitcast <i1 x N> to iN:
1044         let i_ = bx.bitcast(i1xn, bx.type_ix(in_len));
1045         // Zero-extend iN to the bitmask type:
1046         return Ok(bx.zext(i_, bx.type_ix(expected_int_bits)));
1047     }
1048
1049     fn simd_simple_float_intrinsic(
1050         name: Symbol,
1051         in_elem: &::rustc_middle::ty::TyS<'_>,
1052         in_ty: &::rustc_middle::ty::TyS<'_>,
1053         in_len: u64,
1054         bx: &mut Builder<'a, 'll, 'tcx>,
1055         span: Span,
1056         args: &[OperandRef<'tcx, &'ll Value>],
1057     ) -> Result<&'ll Value, ()> {
1058         macro_rules! emit_error {
1059             ($msg: tt) => {
1060                 emit_error!($msg, )
1061             };
1062             ($msg: tt, $($fmt: tt)*) => {
1063                 span_invalid_monomorphization_error(
1064                     bx.sess(), span,
1065                     &format!(concat!("invalid monomorphization of `{}` intrinsic: ", $msg),
1066                              name, $($fmt)*));
1067             }
1068         }
1069         macro_rules! return_error {
1070             ($($fmt: tt)*) => {
1071                 {
1072                     emit_error!($($fmt)*);
1073                     return Err(());
1074                 }
1075             }
1076         }
1077
1078         let (elem_ty_str, elem_ty) = if let ty::Float(f) = in_elem.kind() {
1079             let elem_ty = bx.cx.type_float_from_ty(*f);
1080             match f.bit_width() {
1081                 32 => ("f32", elem_ty),
1082                 64 => ("f64", elem_ty),
1083                 _ => {
1084                     return_error!(
1085                         "unsupported element type `{}` of floating-point vector `{}`",
1086                         f.name_str(),
1087                         in_ty
1088                     );
1089                 }
1090             }
1091         } else {
1092             return_error!("`{}` is not a floating-point type", in_ty);
1093         };
1094
1095         let vec_ty = bx.type_vector(elem_ty, in_len);
1096
1097         let (intr_name, fn_ty) = match name {
1098             sym::simd_ceil => ("ceil", bx.type_func(&[vec_ty], vec_ty)),
1099             sym::simd_fabs => ("fabs", bx.type_func(&[vec_ty], vec_ty)),
1100             sym::simd_fcos => ("cos", bx.type_func(&[vec_ty], vec_ty)),
1101             sym::simd_fexp2 => ("exp2", bx.type_func(&[vec_ty], vec_ty)),
1102             sym::simd_fexp => ("exp", bx.type_func(&[vec_ty], vec_ty)),
1103             sym::simd_flog10 => ("log10", bx.type_func(&[vec_ty], vec_ty)),
1104             sym::simd_flog2 => ("log2", bx.type_func(&[vec_ty], vec_ty)),
1105             sym::simd_flog => ("log", bx.type_func(&[vec_ty], vec_ty)),
1106             sym::simd_floor => ("floor", bx.type_func(&[vec_ty], vec_ty)),
1107             sym::simd_fma => ("fma", bx.type_func(&[vec_ty, vec_ty, vec_ty], vec_ty)),
1108             sym::simd_fpowi => ("powi", bx.type_func(&[vec_ty, bx.type_i32()], vec_ty)),
1109             sym::simd_fpow => ("pow", bx.type_func(&[vec_ty, vec_ty], vec_ty)),
1110             sym::simd_fsin => ("sin", bx.type_func(&[vec_ty], vec_ty)),
1111             sym::simd_fsqrt => ("sqrt", bx.type_func(&[vec_ty], vec_ty)),
1112             sym::simd_round => ("round", bx.type_func(&[vec_ty], vec_ty)),
1113             sym::simd_trunc => ("trunc", bx.type_func(&[vec_ty], vec_ty)),
1114             _ => return_error!("unrecognized intrinsic `{}`", name),
1115         };
1116         let llvm_name = &format!("llvm.{0}.v{1}{2}", intr_name, in_len, elem_ty_str);
1117         let f = bx.declare_cfn(&llvm_name, llvm::UnnamedAddr::No, fn_ty);
1118         let c = bx.call(f, &args.iter().map(|arg| arg.immediate()).collect::<Vec<_>>(), None);
1119         Ok(c)
1120     }
1121
1122     if std::matches!(
1123         name,
1124         sym::simd_ceil
1125             | sym::simd_fabs
1126             | sym::simd_fcos
1127             | sym::simd_fexp2
1128             | sym::simd_fexp
1129             | sym::simd_flog10
1130             | sym::simd_flog2
1131             | sym::simd_flog
1132             | sym::simd_floor
1133             | sym::simd_fma
1134             | sym::simd_fpow
1135             | sym::simd_fpowi
1136             | sym::simd_fsin
1137             | sym::simd_fsqrt
1138             | sym::simd_round
1139             | sym::simd_trunc
1140     ) {
1141         return simd_simple_float_intrinsic(name, in_elem, in_ty, in_len, bx, span, args);
1142     }
1143
1144     // FIXME: use:
1145     //  https://github.com/llvm-mirror/llvm/blob/master/include/llvm/IR/Function.h#L182
1146     //  https://github.com/llvm-mirror/llvm/blob/master/include/llvm/IR/Intrinsics.h#L81
1147     fn llvm_vector_str(elem_ty: Ty<'_>, vec_len: u64, no_pointers: usize) -> String {
1148         let p0s: String = "p0".repeat(no_pointers);
1149         match *elem_ty.kind() {
1150             ty::Int(v) => format!("v{}{}i{}", vec_len, p0s, v.bit_width().unwrap()),
1151             ty::Uint(v) => format!("v{}{}i{}", vec_len, p0s, v.bit_width().unwrap()),
1152             ty::Float(v) => format!("v{}{}f{}", vec_len, p0s, v.bit_width()),
1153             _ => unreachable!(),
1154         }
1155     }
1156
1157     fn llvm_vector_ty(
1158         cx: &CodegenCx<'ll, '_>,
1159         elem_ty: Ty<'_>,
1160         vec_len: u64,
1161         mut no_pointers: usize,
1162     ) -> &'ll Type {
1163         // FIXME: use cx.layout_of(ty).llvm_type() ?
1164         let mut elem_ty = match *elem_ty.kind() {
1165             ty::Int(v) => cx.type_int_from_ty(v),
1166             ty::Uint(v) => cx.type_uint_from_ty(v),
1167             ty::Float(v) => cx.type_float_from_ty(v),
1168             _ => unreachable!(),
1169         };
1170         while no_pointers > 0 {
1171             elem_ty = cx.type_ptr_to(elem_ty);
1172             no_pointers -= 1;
1173         }
1174         cx.type_vector(elem_ty, vec_len)
1175     }
1176
1177     if name == sym::simd_gather {
1178         // simd_gather(values: <N x T>, pointers: <N x *_ T>,
1179         //             mask: <N x i{M}>) -> <N x T>
1180         // * N: number of elements in the input vectors
1181         // * T: type of the element to load
1182         // * M: any integer width is supported, will be truncated to i1
1183
1184         // All types must be simd vector types
1185         require_simd!(in_ty, "first");
1186         require_simd!(arg_tys[1], "second");
1187         require_simd!(arg_tys[2], "third");
1188         require_simd!(ret_ty, "return");
1189
1190         // Of the same length:
1191         let (out_len, _) = arg_tys[1].simd_size_and_type(bx.tcx());
1192         let (out_len2, _) = arg_tys[2].simd_size_and_type(bx.tcx());
1193         require!(
1194             in_len == out_len,
1195             "expected {} argument with length {} (same as input type `{}`), \
1196              found `{}` with length {}",
1197             "second",
1198             in_len,
1199             in_ty,
1200             arg_tys[1],
1201             out_len
1202         );
1203         require!(
1204             in_len == out_len2,
1205             "expected {} argument with length {} (same as input type `{}`), \
1206              found `{}` with length {}",
1207             "third",
1208             in_len,
1209             in_ty,
1210             arg_tys[2],
1211             out_len2
1212         );
1213
1214         // The return type must match the first argument type
1215         require!(ret_ty == in_ty, "expected return type `{}`, found `{}`", in_ty, ret_ty);
1216
1217         // This counts how many pointers
1218         fn ptr_count(t: Ty<'_>) -> usize {
1219             match t.kind() {
1220                 ty::RawPtr(p) => 1 + ptr_count(p.ty),
1221                 _ => 0,
1222             }
1223         }
1224
1225         // Non-ptr type
1226         fn non_ptr(t: Ty<'_>) -> Ty<'_> {
1227             match t.kind() {
1228                 ty::RawPtr(p) => non_ptr(p.ty),
1229                 _ => t,
1230             }
1231         }
1232
1233         // The second argument must be a simd vector with an element type that's a pointer
1234         // to the element type of the first argument
1235         let (_, element_ty0) = arg_tys[0].simd_size_and_type(bx.tcx());
1236         let (_, element_ty1) = arg_tys[1].simd_size_and_type(bx.tcx());
1237         let (pointer_count, underlying_ty) = match element_ty1.kind() {
1238             ty::RawPtr(p) if p.ty == in_elem => (ptr_count(element_ty1), non_ptr(element_ty1)),
1239             _ => {
1240                 require!(
1241                     false,
1242                     "expected element type `{}` of second argument `{}` \
1243                         to be a pointer to the element type `{}` of the first \
1244                         argument `{}`, found `{}` != `*_ {}`",
1245                     element_ty1,
1246                     arg_tys[1],
1247                     in_elem,
1248                     in_ty,
1249                     element_ty1,
1250                     in_elem
1251                 );
1252                 unreachable!();
1253             }
1254         };
1255         assert!(pointer_count > 0);
1256         assert_eq!(pointer_count - 1, ptr_count(element_ty0));
1257         assert_eq!(underlying_ty, non_ptr(element_ty0));
1258
1259         // The element type of the third argument must be a signed integer type of any width:
1260         let (_, element_ty2) = arg_tys[2].simd_size_and_type(bx.tcx());
1261         match element_ty2.kind() {
1262             ty::Int(_) => (),
1263             _ => {
1264                 require!(
1265                     false,
1266                     "expected element type `{}` of third argument `{}` \
1267                                  to be a signed integer type",
1268                     element_ty2,
1269                     arg_tys[2]
1270                 );
1271             }
1272         }
1273
1274         // Alignment of T, must be a constant integer value:
1275         let alignment_ty = bx.type_i32();
1276         let alignment = bx.const_i32(bx.align_of(in_elem).bytes() as i32);
1277
1278         // Truncate the mask vector to a vector of i1s:
1279         let (mask, mask_ty) = {
1280             let i1 = bx.type_i1();
1281             let i1xn = bx.type_vector(i1, in_len);
1282             (bx.trunc(args[2].immediate(), i1xn), i1xn)
1283         };
1284
1285         // Type of the vector of pointers:
1286         let llvm_pointer_vec_ty = llvm_vector_ty(bx, underlying_ty, in_len, pointer_count);
1287         let llvm_pointer_vec_str = llvm_vector_str(underlying_ty, in_len, pointer_count);
1288
1289         // Type of the vector of elements:
1290         let llvm_elem_vec_ty = llvm_vector_ty(bx, underlying_ty, in_len, pointer_count - 1);
1291         let llvm_elem_vec_str = llvm_vector_str(underlying_ty, in_len, pointer_count - 1);
1292
1293         let llvm_intrinsic =
1294             format!("llvm.masked.gather.{}.{}", llvm_elem_vec_str, llvm_pointer_vec_str);
1295         let f = bx.declare_cfn(
1296             &llvm_intrinsic,
1297             llvm::UnnamedAddr::No,
1298             bx.type_func(
1299                 &[llvm_pointer_vec_ty, alignment_ty, mask_ty, llvm_elem_vec_ty],
1300                 llvm_elem_vec_ty,
1301             ),
1302         );
1303         let v = bx.call(f, &[args[1].immediate(), alignment, mask, args[0].immediate()], None);
1304         return Ok(v);
1305     }
1306
1307     if name == sym::simd_scatter {
1308         // simd_scatter(values: <N x T>, pointers: <N x *mut T>,
1309         //             mask: <N x i{M}>) -> ()
1310         // * N: number of elements in the input vectors
1311         // * T: type of the element to load
1312         // * M: any integer width is supported, will be truncated to i1
1313
1314         // All types must be simd vector types
1315         require_simd!(in_ty, "first");
1316         require_simd!(arg_tys[1], "second");
1317         require_simd!(arg_tys[2], "third");
1318
1319         // Of the same length:
1320         let (element_len1, _) = arg_tys[1].simd_size_and_type(bx.tcx());
1321         let (element_len2, _) = arg_tys[2].simd_size_and_type(bx.tcx());
1322         require!(
1323             in_len == element_len1,
1324             "expected {} argument with length {} (same as input type `{}`), \
1325             found `{}` with length {}",
1326             "second",
1327             in_len,
1328             in_ty,
1329             arg_tys[1],
1330             element_len1
1331         );
1332         require!(
1333             in_len == element_len2,
1334             "expected {} argument with length {} (same as input type `{}`), \
1335             found `{}` with length {}",
1336             "third",
1337             in_len,
1338             in_ty,
1339             arg_tys[2],
1340             element_len2
1341         );
1342
1343         // This counts how many pointers
1344         fn ptr_count(t: Ty<'_>) -> usize {
1345             match t.kind() {
1346                 ty::RawPtr(p) => 1 + ptr_count(p.ty),
1347                 _ => 0,
1348             }
1349         }
1350
1351         // Non-ptr type
1352         fn non_ptr(t: Ty<'_>) -> Ty<'_> {
1353             match t.kind() {
1354                 ty::RawPtr(p) => non_ptr(p.ty),
1355                 _ => t,
1356             }
1357         }
1358
1359         // The second argument must be a simd vector with an element type that's a pointer
1360         // to the element type of the first argument
1361         let (_, element_ty0) = arg_tys[0].simd_size_and_type(bx.tcx());
1362         let (_, element_ty1) = arg_tys[1].simd_size_and_type(bx.tcx());
1363         let (_, element_ty2) = arg_tys[2].simd_size_and_type(bx.tcx());
1364         let (pointer_count, underlying_ty) = match element_ty1.kind() {
1365             ty::RawPtr(p) if p.ty == in_elem && p.mutbl == hir::Mutability::Mut => {
1366                 (ptr_count(element_ty1), non_ptr(element_ty1))
1367             }
1368             _ => {
1369                 require!(
1370                     false,
1371                     "expected element type `{}` of second argument `{}` \
1372                         to be a pointer to the element type `{}` of the first \
1373                         argument `{}`, found `{}` != `*mut {}`",
1374                     element_ty1,
1375                     arg_tys[1],
1376                     in_elem,
1377                     in_ty,
1378                     element_ty1,
1379                     in_elem
1380                 );
1381                 unreachable!();
1382             }
1383         };
1384         assert!(pointer_count > 0);
1385         assert_eq!(pointer_count - 1, ptr_count(element_ty0));
1386         assert_eq!(underlying_ty, non_ptr(element_ty0));
1387
1388         // The element type of the third argument must be a signed integer type of any width:
1389         match element_ty2.kind() {
1390             ty::Int(_) => (),
1391             _ => {
1392                 require!(
1393                     false,
1394                     "expected element type `{}` of third argument `{}` \
1395                          be a signed integer type",
1396                     element_ty2,
1397                     arg_tys[2]
1398                 );
1399             }
1400         }
1401
1402         // Alignment of T, must be a constant integer value:
1403         let alignment_ty = bx.type_i32();
1404         let alignment = bx.const_i32(bx.align_of(in_elem).bytes() as i32);
1405
1406         // Truncate the mask vector to a vector of i1s:
1407         let (mask, mask_ty) = {
1408             let i1 = bx.type_i1();
1409             let i1xn = bx.type_vector(i1, in_len);
1410             (bx.trunc(args[2].immediate(), i1xn), i1xn)
1411         };
1412
1413         let ret_t = bx.type_void();
1414
1415         // Type of the vector of pointers:
1416         let llvm_pointer_vec_ty = llvm_vector_ty(bx, underlying_ty, in_len, pointer_count);
1417         let llvm_pointer_vec_str = llvm_vector_str(underlying_ty, in_len, pointer_count);
1418
1419         // Type of the vector of elements:
1420         let llvm_elem_vec_ty = llvm_vector_ty(bx, underlying_ty, in_len, pointer_count - 1);
1421         let llvm_elem_vec_str = llvm_vector_str(underlying_ty, in_len, pointer_count - 1);
1422
1423         let llvm_intrinsic =
1424             format!("llvm.masked.scatter.{}.{}", llvm_elem_vec_str, llvm_pointer_vec_str);
1425         let f = bx.declare_cfn(
1426             &llvm_intrinsic,
1427             llvm::UnnamedAddr::No,
1428             bx.type_func(&[llvm_elem_vec_ty, llvm_pointer_vec_ty, alignment_ty, mask_ty], ret_t),
1429         );
1430         let v = bx.call(f, &[args[0].immediate(), args[1].immediate(), alignment, mask], None);
1431         return Ok(v);
1432     }
1433
1434     macro_rules! arith_red {
1435         ($name:ident : $integer_reduce:ident, $float_reduce:ident, $ordered:expr, $op:ident,
1436          $identity:expr) => {
1437             if name == sym::$name {
1438                 require!(
1439                     ret_ty == in_elem,
1440                     "expected return type `{}` (element of input `{}`), found `{}`",
1441                     in_elem,
1442                     in_ty,
1443                     ret_ty
1444                 );
1445                 return match in_elem.kind() {
1446                     ty::Int(_) | ty::Uint(_) => {
1447                         let r = bx.$integer_reduce(args[0].immediate());
1448                         if $ordered {
1449                             // if overflow occurs, the result is the
1450                             // mathematical result modulo 2^n:
1451                             Ok(bx.$op(args[1].immediate(), r))
1452                         } else {
1453                             Ok(bx.$integer_reduce(args[0].immediate()))
1454                         }
1455                     }
1456                     ty::Float(f) => {
1457                         let acc = if $ordered {
1458                             // ordered arithmetic reductions take an accumulator
1459                             args[1].immediate()
1460                         } else {
1461                             // unordered arithmetic reductions use the identity accumulator
1462                             match f.bit_width() {
1463                                 32 => bx.const_real(bx.type_f32(), $identity),
1464                                 64 => bx.const_real(bx.type_f64(), $identity),
1465                                 v => return_error!(
1466                                     r#"
1467 unsupported {} from `{}` with element `{}` of size `{}` to `{}`"#,
1468                                     sym::$name,
1469                                     in_ty,
1470                                     in_elem,
1471                                     v,
1472                                     ret_ty
1473                                 ),
1474                             }
1475                         };
1476                         Ok(bx.$float_reduce(acc, args[0].immediate()))
1477                     }
1478                     _ => return_error!(
1479                         "unsupported {} from `{}` with element `{}` to `{}`",
1480                         sym::$name,
1481                         in_ty,
1482                         in_elem,
1483                         ret_ty
1484                     ),
1485                 };
1486             }
1487         };
1488     }
1489
1490     arith_red!(simd_reduce_add_ordered: vector_reduce_add, vector_reduce_fadd, true, add, 0.0);
1491     arith_red!(simd_reduce_mul_ordered: vector_reduce_mul, vector_reduce_fmul, true, mul, 1.0);
1492     arith_red!(
1493         simd_reduce_add_unordered: vector_reduce_add,
1494         vector_reduce_fadd_fast,
1495         false,
1496         add,
1497         0.0
1498     );
1499     arith_red!(
1500         simd_reduce_mul_unordered: vector_reduce_mul,
1501         vector_reduce_fmul_fast,
1502         false,
1503         mul,
1504         1.0
1505     );
1506
1507     macro_rules! minmax_red {
1508         ($name:ident: $int_red:ident, $float_red:ident) => {
1509             if name == sym::$name {
1510                 require!(
1511                     ret_ty == in_elem,
1512                     "expected return type `{}` (element of input `{}`), found `{}`",
1513                     in_elem,
1514                     in_ty,
1515                     ret_ty
1516                 );
1517                 return match in_elem.kind() {
1518                     ty::Int(_i) => Ok(bx.$int_red(args[0].immediate(), true)),
1519                     ty::Uint(_u) => Ok(bx.$int_red(args[0].immediate(), false)),
1520                     ty::Float(_f) => Ok(bx.$float_red(args[0].immediate())),
1521                     _ => return_error!(
1522                         "unsupported {} from `{}` with element `{}` to `{}`",
1523                         sym::$name,
1524                         in_ty,
1525                         in_elem,
1526                         ret_ty
1527                     ),
1528                 };
1529             }
1530         };
1531     }
1532
1533     minmax_red!(simd_reduce_min: vector_reduce_min, vector_reduce_fmin);
1534     minmax_red!(simd_reduce_max: vector_reduce_max, vector_reduce_fmax);
1535
1536     minmax_red!(simd_reduce_min_nanless: vector_reduce_min, vector_reduce_fmin_fast);
1537     minmax_red!(simd_reduce_max_nanless: vector_reduce_max, vector_reduce_fmax_fast);
1538
1539     macro_rules! bitwise_red {
1540         ($name:ident : $red:ident, $boolean:expr) => {
1541             if name == sym::$name {
1542                 let input = if !$boolean {
1543                     require!(
1544                         ret_ty == in_elem,
1545                         "expected return type `{}` (element of input `{}`), found `{}`",
1546                         in_elem,
1547                         in_ty,
1548                         ret_ty
1549                     );
1550                     args[0].immediate()
1551                 } else {
1552                     match in_elem.kind() {
1553                         ty::Int(_) | ty::Uint(_) => {}
1554                         _ => return_error!(
1555                             "unsupported {} from `{}` with element `{}` to `{}`",
1556                             sym::$name,
1557                             in_ty,
1558                             in_elem,
1559                             ret_ty
1560                         ),
1561                     }
1562
1563                     // boolean reductions operate on vectors of i1s:
1564                     let i1 = bx.type_i1();
1565                     let i1xn = bx.type_vector(i1, in_len as u64);
1566                     bx.trunc(args[0].immediate(), i1xn)
1567                 };
1568                 return match in_elem.kind() {
1569                     ty::Int(_) | ty::Uint(_) => {
1570                         let r = bx.$red(input);
1571                         Ok(if !$boolean { r } else { bx.zext(r, bx.type_bool()) })
1572                     }
1573                     _ => return_error!(
1574                         "unsupported {} from `{}` with element `{}` to `{}`",
1575                         sym::$name,
1576                         in_ty,
1577                         in_elem,
1578                         ret_ty
1579                     ),
1580                 };
1581             }
1582         };
1583     }
1584
1585     bitwise_red!(simd_reduce_and: vector_reduce_and, false);
1586     bitwise_red!(simd_reduce_or: vector_reduce_or, false);
1587     bitwise_red!(simd_reduce_xor: vector_reduce_xor, false);
1588     bitwise_red!(simd_reduce_all: vector_reduce_and, true);
1589     bitwise_red!(simd_reduce_any: vector_reduce_or, true);
1590
1591     if name == sym::simd_cast {
1592         require_simd!(ret_ty, "return");
1593         let (out_len, out_elem) = ret_ty.simd_size_and_type(bx.tcx());
1594         require!(
1595             in_len == out_len,
1596             "expected return type with length {} (same as input type `{}`), \
1597                   found `{}` with length {}",
1598             in_len,
1599             in_ty,
1600             ret_ty,
1601             out_len
1602         );
1603         // casting cares about nominal type, not just structural type
1604         if in_elem == out_elem {
1605             return Ok(args[0].immediate());
1606         }
1607
1608         enum Style {
1609             Float,
1610             Int(/* is signed? */ bool),
1611             Unsupported,
1612         }
1613
1614         let (in_style, in_width) = match in_elem.kind() {
1615             // vectors of pointer-sized integers should've been
1616             // disallowed before here, so this unwrap is safe.
1617             ty::Int(i) => (Style::Int(true), i.bit_width().unwrap()),
1618             ty::Uint(u) => (Style::Int(false), u.bit_width().unwrap()),
1619             ty::Float(f) => (Style::Float, f.bit_width()),
1620             _ => (Style::Unsupported, 0),
1621         };
1622         let (out_style, out_width) = match out_elem.kind() {
1623             ty::Int(i) => (Style::Int(true), i.bit_width().unwrap()),
1624             ty::Uint(u) => (Style::Int(false), u.bit_width().unwrap()),
1625             ty::Float(f) => (Style::Float, f.bit_width()),
1626             _ => (Style::Unsupported, 0),
1627         };
1628
1629         match (in_style, out_style) {
1630             (Style::Int(in_is_signed), Style::Int(_)) => {
1631                 return Ok(match in_width.cmp(&out_width) {
1632                     Ordering::Greater => bx.trunc(args[0].immediate(), llret_ty),
1633                     Ordering::Equal => args[0].immediate(),
1634                     Ordering::Less => {
1635                         if in_is_signed {
1636                             bx.sext(args[0].immediate(), llret_ty)
1637                         } else {
1638                             bx.zext(args[0].immediate(), llret_ty)
1639                         }
1640                     }
1641                 });
1642             }
1643             (Style::Int(in_is_signed), Style::Float) => {
1644                 return Ok(if in_is_signed {
1645                     bx.sitofp(args[0].immediate(), llret_ty)
1646                 } else {
1647                     bx.uitofp(args[0].immediate(), llret_ty)
1648                 });
1649             }
1650             (Style::Float, Style::Int(out_is_signed)) => {
1651                 return Ok(if out_is_signed {
1652                     bx.fptosi(args[0].immediate(), llret_ty)
1653                 } else {
1654                     bx.fptoui(args[0].immediate(), llret_ty)
1655                 });
1656             }
1657             (Style::Float, Style::Float) => {
1658                 return Ok(match in_width.cmp(&out_width) {
1659                     Ordering::Greater => bx.fptrunc(args[0].immediate(), llret_ty),
1660                     Ordering::Equal => args[0].immediate(),
1661                     Ordering::Less => bx.fpext(args[0].immediate(), llret_ty),
1662                 });
1663             }
1664             _ => { /* Unsupported. Fallthrough. */ }
1665         }
1666         require!(
1667             false,
1668             "unsupported cast from `{}` with element `{}` to `{}` with element `{}`",
1669             in_ty,
1670             in_elem,
1671             ret_ty,
1672             out_elem
1673         );
1674     }
1675     macro_rules! arith_binary {
1676         ($($name: ident: $($($p: ident),* => $call: ident),*;)*) => {
1677             $(if name == sym::$name {
1678                 match in_elem.kind() {
1679                     $($(ty::$p(_))|* => {
1680                         return Ok(bx.$call(args[0].immediate(), args[1].immediate()))
1681                     })*
1682                     _ => {},
1683                 }
1684                 require!(false,
1685                          "unsupported operation on `{}` with element `{}`",
1686                          in_ty,
1687                          in_elem)
1688             })*
1689         }
1690     }
1691     arith_binary! {
1692         simd_add: Uint, Int => add, Float => fadd;
1693         simd_sub: Uint, Int => sub, Float => fsub;
1694         simd_mul: Uint, Int => mul, Float => fmul;
1695         simd_div: Uint => udiv, Int => sdiv, Float => fdiv;
1696         simd_rem: Uint => urem, Int => srem, Float => frem;
1697         simd_shl: Uint, Int => shl;
1698         simd_shr: Uint => lshr, Int => ashr;
1699         simd_and: Uint, Int => and;
1700         simd_or: Uint, Int => or;
1701         simd_xor: Uint, Int => xor;
1702         simd_fmax: Float => maxnum;
1703         simd_fmin: Float => minnum;
1704
1705     }
1706     macro_rules! arith_unary {
1707         ($($name: ident: $($($p: ident),* => $call: ident),*;)*) => {
1708             $(if name == sym::$name {
1709                 match in_elem.kind() {
1710                     $($(ty::$p(_))|* => {
1711                         return Ok(bx.$call(args[0].immediate()))
1712                     })*
1713                     _ => {},
1714                 }
1715                 require!(false,
1716                          "unsupported operation on `{}` with element `{}`",
1717                          in_ty,
1718                          in_elem)
1719             })*
1720         }
1721     }
1722     arith_unary! {
1723         simd_neg: Int => neg, Float => fneg;
1724     }
1725
1726     if name == sym::simd_saturating_add || name == sym::simd_saturating_sub {
1727         let lhs = args[0].immediate();
1728         let rhs = args[1].immediate();
1729         let is_add = name == sym::simd_saturating_add;
1730         let ptr_bits = bx.tcx().data_layout.pointer_size.bits() as _;
1731         let (signed, elem_width, elem_ty) = match *in_elem.kind() {
1732             ty::Int(i) => (true, i.bit_width().unwrap_or(ptr_bits), bx.cx.type_int_from_ty(i)),
1733             ty::Uint(i) => (false, i.bit_width().unwrap_or(ptr_bits), bx.cx.type_uint_from_ty(i)),
1734             _ => {
1735                 return_error!(
1736                     "expected element type `{}` of vector type `{}` \
1737                      to be a signed or unsigned integer type",
1738                     arg_tys[0].simd_size_and_type(bx.tcx()).1,
1739                     arg_tys[0]
1740                 );
1741             }
1742         };
1743         let llvm_intrinsic = &format!(
1744             "llvm.{}{}.sat.v{}i{}",
1745             if signed { 's' } else { 'u' },
1746             if is_add { "add" } else { "sub" },
1747             in_len,
1748             elem_width
1749         );
1750         let vec_ty = bx.cx.type_vector(elem_ty, in_len as u64);
1751
1752         let f = bx.declare_cfn(
1753             &llvm_intrinsic,
1754             llvm::UnnamedAddr::No,
1755             bx.type_func(&[vec_ty, vec_ty], vec_ty),
1756         );
1757         let v = bx.call(f, &[lhs, rhs], None);
1758         return Ok(v);
1759     }
1760
1761     span_bug!(span, "unknown SIMD intrinsic");
1762 }
1763
1764 // Returns the width of an int Ty, and if it's signed or not
1765 // Returns None if the type is not an integer
1766 // FIXME: there’s multiple of this functions, investigate using some of the already existing
1767 // stuffs.
1768 fn int_type_width_signed(ty: Ty<'_>, cx: &CodegenCx<'_, '_>) -> Option<(u64, bool)> {
1769     match ty.kind() {
1770         ty::Int(t) => {
1771             Some((t.bit_width().unwrap_or(u64::from(cx.tcx.sess.target.pointer_width)), true))
1772         }
1773         ty::Uint(t) => {
1774             Some((t.bit_width().unwrap_or(u64::from(cx.tcx.sess.target.pointer_width)), false))
1775         }
1776         _ => None,
1777     }
1778 }