src/librustc_target/abi/call/mod.rs

   1 // Copyright 2017 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use abi::{self, Abi, Align, FieldPlacement, Size};
  12 use abi::{HasDataLayout, LayoutOf, TyLayout, TyLayoutMethods};
  13 use spec::HasTargetSpec;
  14
  15 mod aarch64;
  16 mod arm;
  17 mod asmjs;
  18 mod hexagon;
  19 mod mips;
  20 mod mips64;
  21 mod msp430;
  22 mod nvptx;
  23 mod nvptx64;
  24 mod powerpc;
  25 mod powerpc64;
  26 mod s390x;
  27 mod sparc;
  28 mod sparc64;
  29 mod x86;
  30 mod x86_64;
  31 mod x86_win64;
  32 mod wasm32;
  33
  34 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
  35 pub enum PassMode {
  36     /// Ignore the argument (useful for empty struct).
  37     Ignore,
  38     /// Pass the argument directly.
  39     Direct(ArgAttributes),
  40     /// Pass a pair's elements directly in two arguments.
  41     Pair(ArgAttributes, ArgAttributes),
  42     /// Pass the argument after casting it, to either
  43     /// a single uniform or a pair of registers.
  44     Cast(CastTarget),
  45     /// Pass the argument indirectly via a hidden pointer.
  46     Indirect(ArgAttributes),
  47 }
  48
  49 // Hack to disable non_upper_case_globals only for the bitflags! and not for the rest
  50 // of this module
  51 pub use self::attr_impl::ArgAttribute;
  52
  53 #[allow(non_upper_case_globals)]
  54 #[allow(unused)]
  55 mod attr_impl {
  56     // The subset of llvm::Attribute needed for arguments, packed into a bitfield.
  57     bitflags! {
  58         #[derive(Default)]
  59         pub struct ArgAttribute: u16 {
  60             const ByVal     = 1 << 0;
  61             const NoAlias   = 1 << 1;
  62             const NoCapture = 1 << 2;
  63             const NonNull   = 1 << 3;
  64             const ReadOnly  = 1 << 4;
  65             const SExt      = 1 << 5;
  66             const StructRet = 1 << 6;
  67             const ZExt      = 1 << 7;
  68             const InReg     = 1 << 8;
  69         }
  70     }
  71 }
  72
  73 /// A compact representation of LLVM attributes (at least those relevant for this module)
  74 /// that can be manipulated without interacting with LLVM's Attribute machinery.
  75 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
  76 pub struct ArgAttributes {
  77     pub regular: ArgAttribute,
  78     pub pointee_size: Size,
  79     pub pointee_align: Option<Align>
  80 }
  81
  82 impl ArgAttributes {
  83     pub fn new() -> Self {
  84         ArgAttributes {
  85             regular: ArgAttribute::default(),
  86             pointee_size: Size::ZERO,
  87             pointee_align: None,
  88         }
  89     }
  90
  91     pub fn set(&mut self, attr: ArgAttribute) -> &mut Self {
  92         self.regular = self.regular | attr;
  93         self
  94     }
  95
  96     pub fn contains(&self, attr: ArgAttribute) -> bool {
  97         self.regular.contains(attr)
  98     }
  99 }
 100
 101 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 102 pub enum RegKind {
 103     Integer,
 104     Float,
 105     Vector
 106 }
 107
 108 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 109 pub struct Reg {
 110     pub kind: RegKind,
 111     pub size: Size,
 112 }
 113
 114 macro_rules! reg_ctor {
 115     ($name:ident, $kind:ident, $bits:expr) => {
 116         pub fn $name() -> Reg {
 117             Reg {
 118                 kind: RegKind::$kind,
 119                 size: Size::from_bits($bits)
 120             }
 121         }
 122     }
 123 }
 124
 125 impl Reg {
 126     reg_ctor!(i8, Integer, 8);
 127     reg_ctor!(i16, Integer, 16);
 128     reg_ctor!(i32, Integer, 32);
 129     reg_ctor!(i64, Integer, 64);
 130
 131     reg_ctor!(f32, Float, 32);
 132     reg_ctor!(f64, Float, 64);
 133 }
 134
 135 impl Reg {
 136     pub fn align<C: HasDataLayout>(&self, cx: C) -> Align {
 137         let dl = cx.data_layout();
 138         match self.kind {
 139             RegKind::Integer => {
 140                 match self.size.bits() {
 141                     1 => dl.i1_align,
 142                     2...8 => dl.i8_align,
 143                     9...16 => dl.i16_align,
 144                     17...32 => dl.i32_align,
 145                     33...64 => dl.i64_align,
 146                     65...128 => dl.i128_align,
 147                     _ => panic!("unsupported integer: {:?}", self)
 148                 }
 149             }
 150             RegKind::Float => {
 151                 match self.size.bits() {
 152                     32 => dl.f32_align,
 153                     64 => dl.f64_align,
 154                     _ => panic!("unsupported float: {:?}", self)
 155                 }
 156             }
 157             RegKind::Vector => dl.vector_align(self.size)
 158         }
 159     }
 160 }
 161
 162 /// An argument passed entirely registers with the
 163 /// same kind (e.g. HFA / HVA on PPC64 and AArch64).
 164 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
 165 pub struct Uniform {
 166     pub unit: Reg,
 167
 168     /// The total size of the argument, which can be:
 169     /// * equal to `unit.size` (one scalar/vector)
 170     /// * a multiple of `unit.size` (an array of scalar/vectors)
 171     /// * if `unit.kind` is `Integer`, the last element
 172     ///   can be shorter, i.e. `{ i64, i64, i32 }` for
 173     ///   64-bit integers with a total size of 20 bytes
 174     pub total: Size,
 175 }
 176
 177 impl From<Reg> for Uniform {
 178     fn from(unit: Reg) -> Uniform {
 179         Uniform {
 180             unit,
 181             total: unit.size
 182         }
 183     }
 184 }
 185
 186 impl Uniform {
 187     pub fn align<C: HasDataLayout>(&self, cx: C) -> Align {
 188         self.unit.align(cx)
 189     }
 190 }
 191
 192 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
 193 pub struct CastTarget {
 194     pub prefix: [Option<RegKind>; 8],
 195     pub prefix_chunk: Size,
 196     pub rest: Uniform,
 197 }
 198
 199 impl From<Reg> for CastTarget {
 200     fn from(unit: Reg) -> CastTarget {
 201         CastTarget::from(Uniform::from(unit))
 202     }
 203 }
 204
 205 impl From<Uniform> for CastTarget {
 206     fn from(uniform: Uniform) -> CastTarget {
 207         CastTarget {
 208             prefix: [None; 8],
 209             prefix_chunk: Size::ZERO,
 210             rest: uniform
 211         }
 212     }
 213 }
 214
 215 impl CastTarget {
 216     pub fn pair(a: Reg, b: Reg) -> CastTarget {
 217         CastTarget {
 218             prefix: [Some(a.kind), None, None, None, None, None, None, None],
 219             prefix_chunk: a.size,
 220             rest: Uniform::from(b)
 221         }
 222     }
 223
 224     pub fn size<C: HasDataLayout>(&self, cx: C) -> Size {
 225         (self.prefix_chunk * self.prefix.iter().filter(|x| x.is_some()).count() as u64)
 226              .abi_align(self.rest.align(cx)) + self.rest.total
 227     }
 228
 229     pub fn align<C: HasDataLayout>(&self, cx: C) -> Align {
 230         self.prefix.iter()
 231             .filter_map(|x| x.map(|kind| Reg { kind: kind, size: self.prefix_chunk }.align(cx)))
 232             .fold(cx.data_layout().aggregate_align.max(self.rest.align(cx)),
 233                 |acc, align| acc.max(align))
 234     }
 235 }
 236
 237 impl<'a, Ty> TyLayout<'a, Ty> {
 238     fn is_aggregate(&self) -> bool {
 239         match self.abi {
 240             Abi::Uninhabited |
 241             Abi::Scalar(_) |
 242             Abi::Vector { .. } => false,
 243             Abi::ScalarPair(..) |
 244             Abi::Aggregate { .. } => true
 245         }
 246     }
 247
 248     fn homogeneous_aggregate<C>(&self, cx: C) -> Option<Reg>
 249         where Ty: TyLayoutMethods<'a, C> + Copy, C: LayoutOf<Ty = Ty, TyLayout = Self> + Copy
 250     {
 251         match self.abi {
 252             Abi::Uninhabited => None,
 253
 254             // The primitive for this algorithm.
 255             Abi::Scalar(ref scalar) => {
 256                 let kind = match scalar.value {
 257                     abi::Int(..) |
 258                     abi::Pointer => RegKind::Integer,
 259                     abi::Float(_) => RegKind::Float,
 260                 };
 261                 Some(Reg {
 262                     kind,
 263                     size: self.size
 264                 })
 265             }
 266
 267             Abi::Vector { .. } => {
 268                 Some(Reg {
 269                     kind: RegKind::Vector,
 270                     size: self.size
 271                 })
 272             }
 273
 274             Abi::ScalarPair(..) |
 275             Abi::Aggregate { .. } => {
 276                 let mut total = Size::ZERO;
 277                 let mut result = None;
 278
 279                 let is_union = match self.fields {
 280                     FieldPlacement::Array { count, .. } => {
 281                         if count > 0 {
 282                             return self.field(cx, 0).homogeneous_aggregate(cx);
 283                         } else {
 284                             return None;
 285                         }
 286                     }
 287                     FieldPlacement::Union(_) => true,
 288                     FieldPlacement::Arbitrary { .. } => false
 289                 };
 290
 291                 for i in 0..self.fields.count() {
 292                     if !is_union && total != self.fields.offset(i) {
 293                         return None;
 294                     }
 295
 296                     let field = self.field(cx, i);
 297                     match (result, field.homogeneous_aggregate(cx)) {
 298                         // The field itself must be a homogeneous aggregate.
 299                         (_, None) => return None,
 300                         // If this is the first field, record the unit.
 301                         (None, Some(unit)) => {
 302                             result = Some(unit);
 303                         }
 304                         // For all following fields, the unit must be the same.
 305                         (Some(prev_unit), Some(unit)) => {
 306                             if prev_unit != unit {
 307                                 return None;
 308                             }
 309                         }
 310                     }
 311
 312                     // Keep track of the offset (without padding).
 313                     let size = field.size;
 314                     if is_union {
 315                         total = total.max(size);
 316                     } else {
 317                         total += size;
 318                     }
 319                 }
 320
 321                 // There needs to be no padding.
 322                 if total != self.size {
 323                     None
 324                 } else {
 325                     result
 326                 }
 327             }
 328         }
 329     }
 330 }
 331
 332 /// Information about how to pass an argument to,
 333 /// or return a value from, a function, under some ABI.
 334 #[derive(Debug)]
 335 pub struct ArgType<'a, Ty> {
 336     pub layout: TyLayout<'a, Ty>,
 337
 338     /// Dummy argument, which is emitted before the real argument.
 339     pub pad: Option<Reg>,
 340
 341     pub mode: PassMode,
 342 }
 343
 344 impl<'a, Ty> ArgType<'a, Ty> {
 345     pub fn new(layout: TyLayout<'a, Ty>) -> Self {
 346         ArgType {
 347             layout,
 348             pad: None,
 349             mode: PassMode::Direct(ArgAttributes::new()),
 350         }
 351     }
 352
 353     pub fn make_indirect(&mut self) {
 354         assert_eq!(self.mode, PassMode::Direct(ArgAttributes::new()));
 355
 356         // Start with fresh attributes for the pointer.
 357         let mut attrs = ArgAttributes::new();
 358
 359         // For non-immediate arguments the callee gets its own copy of
 360         // the value on the stack, so there are no aliases. It's also
 361         // program-invisible so can't possibly capture
 362         attrs.set(ArgAttribute::NoAlias)
 363              .set(ArgAttribute::NoCapture)
 364              .set(ArgAttribute::NonNull);
 365         attrs.pointee_size = self.layout.size;
 366         // FIXME(eddyb) We should be doing this, but at least on
 367         // i686-pc-windows-msvc, it results in wrong stack offsets.
 368         // attrs.pointee_align = Some(self.layout.align);
 369
 370         self.mode = PassMode::Indirect(attrs);
 371     }
 372
 373     pub fn make_indirect_byval(&mut self) {
 374         self.make_indirect();
 375         match self.mode {
 376             PassMode::Indirect(ref mut attrs) => {
 377                 attrs.set(ArgAttribute::ByVal);
 378             }
 379             _ => unreachable!()
 380         }
 381     }
 382
 383     pub fn extend_integer_width_to(&mut self, bits: u64) {
 384         // Only integers have signedness
 385         if let Abi::Scalar(ref scalar) = self.layout.abi {
 386             if let abi::Int(i, signed) = scalar.value {
 387                 if i.size().bits() < bits {
 388                     if let PassMode::Direct(ref mut attrs) = self.mode {
 389                         attrs.set(if signed {
 390                             ArgAttribute::SExt
 391                         } else {
 392                             ArgAttribute::ZExt
 393                         });
 394                     }
 395                 }
 396             }
 397         }
 398     }
 399
 400     pub fn cast_to<T: Into<CastTarget>>(&mut self, target: T) {
 401         assert_eq!(self.mode, PassMode::Direct(ArgAttributes::new()));
 402         self.mode = PassMode::Cast(target.into());
 403     }
 404
 405     pub fn pad_with(&mut self, reg: Reg) {
 406         self.pad = Some(reg);
 407     }
 408
 409     pub fn is_indirect(&self) -> bool {
 410         match self.mode {
 411             PassMode::Indirect(_) => true,
 412             _ => false
 413         }
 414     }
 415
 416     pub fn is_ignore(&self) -> bool {
 417         self.mode == PassMode::Ignore
 418     }
 419 }
 420
 421 #[derive(Copy, Clone, PartialEq, Debug)]
 422 pub enum Conv {
 423     C,
 424
 425     ArmAapcs,
 426
 427     Msp430Intr,
 428
 429     PtxKernel,
 430
 431     X86Fastcall,
 432     X86Intr,
 433     X86Stdcall,
 434     X86ThisCall,
 435     X86VectorCall,
 436
 437     X86_64SysV,
 438     X86_64Win64,
 439 }
 440
 441 /// Metadata describing how the arguments to a native function
 442 /// should be passed in order to respect the native ABI.
 443 ///
 444 /// I will do my best to describe this structure, but these
 445 /// comments are reverse-engineered and may be inaccurate. -NDM
 446 #[derive(Debug)]
 447 pub struct FnType<'a, Ty> {
 448     /// The LLVM types of each argument.
 449     pub args: Vec<ArgType<'a, Ty>>,
 450
 451     /// LLVM return type.
 452     pub ret: ArgType<'a, Ty>,
 453
 454     pub variadic: bool,
 455
 456     pub conv: Conv,
 457 }
 458
 459 impl<'a, Ty> FnType<'a, Ty> {
 460     pub fn adjust_for_cabi<C>(&mut self, cx: C, abi: ::spec::abi::Abi) -> Result<(), String>
 461         where Ty: TyLayoutMethods<'a, C> + Copy,
 462               C: LayoutOf<Ty = Ty, TyLayout = TyLayout<'a, Ty>> + HasDataLayout + HasTargetSpec
 463     {
 464         match &cx.target_spec().arch[..] {
 465             "x86" => {
 466                 let flavor = if abi == ::spec::abi::Abi::Fastcall {
 467                     x86::Flavor::Fastcall
 468                 } else {
 469                     x86::Flavor::General
 470                 };
 471                 x86::compute_abi_info(cx, self, flavor);
 472             },
 473             "x86_64" => if abi == ::spec::abi::Abi::SysV64 {
 474                 x86_64::compute_abi_info(cx, self);
 475             } else if abi == ::spec::abi::Abi::Win64 || cx.target_spec().options.is_like_windows {
 476                 x86_win64::compute_abi_info(self);
 477             } else {
 478                 x86_64::compute_abi_info(cx, self);
 479             },
 480             "aarch64" => aarch64::compute_abi_info(cx, self),
 481             "arm" => arm::compute_abi_info(cx, self),
 482             "mips" => mips::compute_abi_info(cx, self),
 483             "mips64" => mips64::compute_abi_info(cx, self),
 484             "powerpc" => powerpc::compute_abi_info(cx, self),
 485             "powerpc64" => powerpc64::compute_abi_info(cx, self),
 486             "s390x" => s390x::compute_abi_info(cx, self),
 487             "asmjs" => asmjs::compute_abi_info(cx, self),
 488             "wasm32" => {
 489                 if cx.target_spec().llvm_target.contains("emscripten") {
 490                     asmjs::compute_abi_info(cx, self)
 491                 } else {
 492                     wasm32::compute_abi_info(self)
 493                 }
 494             }
 495             "msp430" => msp430::compute_abi_info(self),
 496             "sparc" => sparc::compute_abi_info(cx, self),
 497             "sparc64" => sparc64::compute_abi_info(cx, self),
 498             "nvptx" => nvptx::compute_abi_info(self),
 499             "nvptx64" => nvptx64::compute_abi_info(self),
 500             "hexagon" => hexagon::compute_abi_info(self),
 501             a => return Err(format!("unrecognized arch \"{}\" in target specification", a))
 502         }
 503
 504         if let PassMode::Indirect(ref mut attrs) = self.ret.mode {
 505             attrs.set(ArgAttribute::StructRet);
 506         }
 507
 508         Ok(())
 509     }
 510 }