src/librustc_codegen_llvm/abi.rs

   1 use crate::llvm::{self, AttributePlace};
   2 use crate::builder::Builder;
   3 use crate::context::CodegenCx;
   4 use crate::type_::Type;
   5 use crate::value::Value;
   6 use crate::type_of::{LayoutLlvmExt};
   7 use rustc_codegen_ssa::MemFlags;
   8 use rustc_codegen_ssa::mir::place::PlaceRef;
   9 use rustc_codegen_ssa::mir::operand::OperandValue;
  10 use rustc_target::abi::call::ArgType;
  11
  12 use rustc_codegen_ssa::traits::*;
  13
  14 use rustc_target::abi::{HasDataLayout, LayoutOf};
  15 use rustc::ty::{Ty};
  16 use rustc::ty::layout::{self};
  17
  18 use libc::c_uint;
  19
  20 pub use rustc_target::spec::abi::Abi;
  21 pub use rustc::ty::layout::{FAT_PTR_ADDR, FAT_PTR_EXTRA};
  22 pub use rustc_target::abi::call::*;
  23
  24 macro_rules! for_each_kind {
  25     ($flags: ident, $f: ident, $($kind: ident),+) => ({
  26         $(if $flags.contains(ArgAttribute::$kind) { $f(llvm::Attribute::$kind) })+
  27     })
  28 }
  29
  30 trait ArgAttributeExt {
  31     fn for_each_kind<F>(&self, f: F) where F: FnMut(llvm::Attribute);
  32 }
  33
  34 impl ArgAttributeExt for ArgAttribute {
  35     fn for_each_kind<F>(&self, mut f: F) where F: FnMut(llvm::Attribute) {
  36         for_each_kind!(self, f,
  37                        NoAlias, NoCapture, NonNull, ReadOnly, SExt, StructRet, ZExt, InReg)
  38     }
  39 }
  40
  41 pub trait ArgAttributesExt {
  42     fn apply_llfn(&self, idx: AttributePlace, llfn: &Value, ty: Option<&Type>);
  43     fn apply_callsite(&self, idx: AttributePlace, callsite: &Value, ty: Option<&Type>);
  44 }
  45
  46 impl ArgAttributesExt for ArgAttributes {
  47     fn apply_llfn(&self, idx: AttributePlace, llfn: &Value, ty: Option<&Type>) {
  48         let mut regular = self.regular;
  49         unsafe {
  50             let deref = self.pointee_size.bytes();
  51             if deref != 0 {
  52                 if regular.contains(ArgAttribute::NonNull) {
  53                     llvm::LLVMRustAddDereferenceableAttr(llfn,
  54                                                          idx.as_uint(),
  55                                                          deref);
  56                 } else {
  57                     llvm::LLVMRustAddDereferenceableOrNullAttr(llfn,
  58                                                                idx.as_uint(),
  59                                                                deref);
  60                 }
  61                 regular -= ArgAttribute::NonNull;
  62             }
  63             if let Some(align) = self.pointee_align {
  64                 llvm::LLVMRustAddAlignmentAttr(llfn,
  65                                                idx.as_uint(),
  66                                                align.bytes() as u32);
  67             }
  68             if regular.contains(ArgAttribute::ByVal) {
  69                 llvm::LLVMRustAddByValAttr(llfn, idx.as_uint(), ty.unwrap());
  70             }
  71             regular.for_each_kind(|attr| attr.apply_llfn(idx, llfn));
  72         }
  73     }
  74
  75     fn apply_callsite(&self, idx: AttributePlace, callsite: &Value, ty: Option<&Type>) {
  76         let mut regular = self.regular;
  77         unsafe {
  78             let deref = self.pointee_size.bytes();
  79             if deref != 0 {
  80                 if regular.contains(ArgAttribute::NonNull) {
  81                     llvm::LLVMRustAddDereferenceableCallSiteAttr(callsite,
  82                                                                  idx.as_uint(),
  83                                                                  deref);
  84                 } else {
  85                     llvm::LLVMRustAddDereferenceableOrNullCallSiteAttr(callsite,
  86                                                                        idx.as_uint(),
  87                                                                        deref);
  88                 }
  89                 regular -= ArgAttribute::NonNull;
  90             }
  91             if let Some(align) = self.pointee_align {
  92                 llvm::LLVMRustAddAlignmentCallSiteAttr(callsite,
  93                                                        idx.as_uint(),
  94                                                        align.bytes() as u32);
  95             }
  96             if regular.contains(ArgAttribute::ByVal) {
  97                 llvm::LLVMRustAddByValCallSiteAttr(callsite, idx.as_uint(), ty.unwrap());
  98             }
  99             regular.for_each_kind(|attr| attr.apply_callsite(idx, callsite));
 100         }
 101     }
 102 }
 103
 104 pub trait LlvmType {
 105     fn llvm_type(&self, cx: &CodegenCx<'ll, '_>) -> &'ll Type;
 106 }
 107
 108 impl LlvmType for Reg {
 109     fn llvm_type(&self, cx: &CodegenCx<'ll, '_>) -> &'ll Type {
 110         match self.kind {
 111             RegKind::Integer => cx.type_ix(self.size.bits()),
 112             RegKind::Float => {
 113                 match self.size.bits() {
 114                     32 => cx.type_f32(),
 115                     64 => cx.type_f64(),
 116                     _ => bug!("unsupported float: {:?}", self)
 117                 }
 118             }
 119             RegKind::Vector => {
 120                 cx.type_vector(cx.type_i8(), self.size.bytes())
 121             }
 122         }
 123     }
 124 }
 125
 126 impl LlvmType for CastTarget {
 127     fn llvm_type(&self, cx: &CodegenCx<'ll, '_>) -> &'ll Type {
 128         let rest_ll_unit = self.rest.unit.llvm_type(cx);
 129         let (rest_count, rem_bytes) = if self.rest.unit.size.bytes() == 0 {
 130             (0, 0)
 131         } else {
 132             (self.rest.total.bytes() / self.rest.unit.size.bytes(),
 133             self.rest.total.bytes() % self.rest.unit.size.bytes())
 134         };
 135
 136         if self.prefix.iter().all(|x| x.is_none()) {
 137             // Simplify to a single unit when there is no prefix and size <= unit size
 138             if self.rest.total <= self.rest.unit.size {
 139                 return rest_ll_unit;
 140             }
 141
 142             // Simplify to array when all chunks are the same size and type
 143             if rem_bytes == 0 {
 144                 return cx.type_array(rest_ll_unit, rest_count);
 145             }
 146         }
 147
 148         // Create list of fields in the main structure
 149         let mut args: Vec<_> =
 150             self.prefix.iter().flat_map(|option_kind| option_kind.map(
 151                 |kind| Reg { kind: kind, size: self.prefix_chunk }.llvm_type(cx)))
 152             .chain((0..rest_count).map(|_| rest_ll_unit))
 153             .collect();
 154
 155         // Append final integer
 156         if rem_bytes != 0 {
 157             // Only integers can be really split further.
 158             assert_eq!(self.rest.unit.kind, RegKind::Integer);
 159             args.push(cx.type_ix(rem_bytes * 8));
 160         }
 161
 162         cx.type_struct(&args, false)
 163     }
 164 }
 165
 166 pub trait ArgTypeExt<'ll, 'tcx> {
 167     fn memory_ty(&self, cx: &CodegenCx<'ll, 'tcx>) -> &'ll Type;
 168     fn store(
 169         &self,
 170         bx: &mut Builder<'_, 'll, 'tcx>,
 171         val: &'ll Value,
 172         dst: PlaceRef<'tcx, &'ll Value>,
 173     );
 174     fn store_fn_arg(
 175         &self,
 176         bx: &mut Builder<'_, 'll, 'tcx>,
 177         idx: &mut usize,
 178         dst: PlaceRef<'tcx, &'ll Value>,
 179     );
 180 }
 181
 182 impl ArgTypeExt<'ll, 'tcx> for ArgType<'tcx, Ty<'tcx>> {
 183     /// Gets the LLVM type for a place of the original Rust type of
 184     /// this argument/return, i.e., the result of `type_of::type_of`.
 185     fn memory_ty(&self, cx: &CodegenCx<'ll, 'tcx>) -> &'ll Type {
 186         self.layout.llvm_type(cx)
 187     }
 188
 189     /// Stores a direct/indirect value described by this ArgType into a
 190     /// place for the original Rust type of this argument/return.
 191     /// Can be used for both storing formal arguments into Rust variables
 192     /// or results of call/invoke instructions into their destinations.
 193     fn store(
 194         &self,
 195         bx: &mut Builder<'_, 'll, 'tcx>,
 196         val: &'ll Value,
 197         dst: PlaceRef<'tcx, &'ll Value>,
 198     ) {
 199         if self.is_ignore() {
 200             return;
 201         }
 202         if self.is_sized_indirect() {
 203             OperandValue::Ref(val, None, self.layout.align.abi).store(bx, dst)
 204         } else if self.is_unsized_indirect() {
 205             bug!("unsized ArgType must be handled through store_fn_arg");
 206         } else if let PassMode::Cast(cast) = self.mode {
 207             // FIXME(eddyb): Figure out when the simpler Store is safe, clang
 208             // uses it for i16 -> {i8, i8}, but not for i24 -> {i8, i8, i8}.
 209             let can_store_through_cast_ptr = false;
 210             if can_store_through_cast_ptr {
 211                 let cast_ptr_llty = bx.type_ptr_to(cast.llvm_type(bx));
 212                 let cast_dst = bx.pointercast(dst.llval, cast_ptr_llty);
 213                 bx.store(val, cast_dst, self.layout.align.abi);
 214             } else {
 215                 // The actual return type is a struct, but the ABI
 216                 // adaptation code has cast it into some scalar type.  The
 217                 // code that follows is the only reliable way I have
 218                 // found to do a transform like i64 -> {i32,i32}.
 219                 // Basically we dump the data onto the stack then memcpy it.
 220                 //
 221                 // Other approaches I tried:
 222                 // - Casting rust ret pointer to the foreign type and using Store
 223                 //   is (a) unsafe if size of foreign type > size of rust type and
 224                 //   (b) runs afoul of strict aliasing rules, yielding invalid
 225                 //   assembly under -O (specifically, the store gets removed).
 226                 // - Truncating foreign type to correct integral type and then
 227                 //   bitcasting to the struct type yields invalid cast errors.
 228
 229                 // We instead thus allocate some scratch space...
 230                 let scratch_size = cast.size(bx);
 231                 let scratch_align = cast.align(bx);
 232                 let llscratch = bx.alloca(cast.llvm_type(bx), scratch_align);
 233                 bx.lifetime_start(llscratch, scratch_size);
 234
 235                 // ...where we first store the value...
 236                 bx.store(val, llscratch, scratch_align);
 237
 238                 // ...and then memcpy it to the intended destination.
 239                 bx.memcpy(
 240                     dst.llval,
 241                     self.layout.align.abi,
 242                     llscratch,
 243                     scratch_align,
 244                     bx.const_usize(self.layout.size.bytes()),
 245                     MemFlags::empty()
 246                 );
 247
 248                 bx.lifetime_end(llscratch, scratch_size);
 249             }
 250         } else {
 251             OperandValue::Immediate(val).store(bx, dst);
 252         }
 253     }
 254
 255     fn store_fn_arg(
 256         &self,
 257         bx: &mut Builder<'a, 'll, 'tcx>,
 258         idx: &mut usize,
 259         dst: PlaceRef<'tcx, &'ll Value>,
 260     ) {
 261         let mut next = || {
 262             let val = llvm::get_param(bx.llfn(), *idx as c_uint);
 263             *idx += 1;
 264             val
 265         };
 266         match self.mode {
 267             PassMode::Ignore => {}
 268             PassMode::Pair(..) => {
 269                 OperandValue::Pair(next(), next()).store(bx, dst);
 270             }
 271             PassMode::Indirect(_, Some(_)) => {
 272                 OperandValue::Ref(next(), Some(next()), self.layout.align.abi).store(bx, dst);
 273             }
 274             PassMode::Direct(_) | PassMode::Indirect(_, None) | PassMode::Cast(_) => {
 275                 let next_arg = next();
 276                 self.store(bx, next_arg, dst);
 277             }
 278         }
 279     }
 280 }
 281
 282 impl ArgTypeMethods<'tcx> for Builder<'a, 'll, 'tcx> {
 283     fn store_fn_arg(
 284         &mut self,
 285         ty: &ArgType<'tcx, Ty<'tcx>>,
 286         idx: &mut usize, dst: PlaceRef<'tcx, Self::Value>
 287     ) {
 288         ty.store_fn_arg(self, idx, dst)
 289     }
 290     fn store_arg_ty(
 291         &mut self,
 292         ty: &ArgType<'tcx, Ty<'tcx>>,
 293         val: &'ll Value,
 294         dst: PlaceRef<'tcx, &'ll Value>
 295     ) {
 296         ty.store(self, val, dst)
 297     }
 298     fn memory_ty(&self, ty: &ArgType<'tcx, Ty<'tcx>>) -> &'ll Type {
 299         ty.memory_ty(self)
 300     }
 301 }
 302
 303 pub trait FnTypeLlvmExt<'tcx> {
 304     fn llvm_type(&self, cx: &CodegenCx<'ll, 'tcx>) -> &'ll Type;
 305     fn ptr_to_llvm_type(&self, cx: &CodegenCx<'ll, 'tcx>) -> &'ll Type;
 306     fn llvm_cconv(&self) -> llvm::CallConv;
 307     fn apply_attrs_llfn(&self, cx: &CodegenCx<'ll, 'tcx>, llfn: &'ll Value);
 308     fn apply_attrs_callsite(&self, bx: &mut Builder<'a, 'll, 'tcx>, callsite: &'ll Value);
 309 }
 310
 311 impl<'tcx> FnTypeLlvmExt<'tcx> for FnType<'tcx, Ty<'tcx>> {
 312     fn llvm_type(&self, cx: &CodegenCx<'ll, 'tcx>) -> &'ll Type {
 313         let args_capacity: usize = self.args.iter().map(|arg|
 314             if arg.pad.is_some() { 1 } else { 0 } +
 315             if let PassMode::Pair(_, _) = arg.mode { 2 } else { 1 }
 316         ).sum();
 317         let mut llargument_tys = Vec::with_capacity(
 318             if let PassMode::Indirect(..) = self.ret.mode { 1 } else { 0 } + args_capacity
 319         );
 320
 321         let llreturn_ty = match self.ret.mode {
 322             PassMode::Ignore => cx.type_void(),
 323             PassMode::Direct(_) | PassMode::Pair(..) => {
 324                 self.ret.layout.immediate_llvm_type(cx)
 325             }
 326             PassMode::Cast(cast) => cast.llvm_type(cx),
 327             PassMode::Indirect(..) => {
 328                 llargument_tys.push(cx.type_ptr_to(self.ret.memory_ty(cx)));
 329                 cx.type_void()
 330             }
 331         };
 332
 333         for arg in &self.args {
 334             // add padding
 335             if let Some(ty) = arg.pad {
 336                 llargument_tys.push(ty.llvm_type(cx));
 337             }
 338
 339             let llarg_ty = match arg.mode {
 340                 PassMode::Ignore => continue,
 341                 PassMode::Direct(_) => arg.layout.immediate_llvm_type(cx),
 342                 PassMode::Pair(..) => {
 343                     llargument_tys.push(arg.layout.scalar_pair_element_llvm_type(cx, 0, true));
 344                     llargument_tys.push(arg.layout.scalar_pair_element_llvm_type(cx, 1, true));
 345                     continue;
 346                 }
 347                 PassMode::Indirect(_, Some(_)) => {
 348                     let ptr_ty = cx.tcx.mk_mut_ptr(arg.layout.ty);
 349                     let ptr_layout = cx.layout_of(ptr_ty);
 350                     llargument_tys.push(ptr_layout.scalar_pair_element_llvm_type(cx, 0, true));
 351                     llargument_tys.push(ptr_layout.scalar_pair_element_llvm_type(cx, 1, true));
 352                     continue;
 353                 }
 354                 PassMode::Cast(cast) => cast.llvm_type(cx),
 355                 PassMode::Indirect(_, None) => cx.type_ptr_to(arg.memory_ty(cx)),
 356             };
 357             llargument_tys.push(llarg_ty);
 358         }
 359
 360         if self.c_variadic {
 361             cx.type_variadic_func(&llargument_tys, llreturn_ty)
 362         } else {
 363             cx.type_func(&llargument_tys, llreturn_ty)
 364         }
 365     }
 366
 367     fn ptr_to_llvm_type(&self, cx: &CodegenCx<'ll, 'tcx>) -> &'ll Type {
 368         unsafe {
 369             llvm::LLVMPointerType(self.llvm_type(cx),
 370                                   cx.data_layout().instruction_address_space as c_uint)
 371         }
 372     }
 373
 374     fn llvm_cconv(&self) -> llvm::CallConv {
 375         match self.conv {
 376             Conv::C => llvm::CCallConv,
 377             Conv::AmdGpuKernel => llvm::AmdGpuKernel,
 378             Conv::ArmAapcs => llvm::ArmAapcsCallConv,
 379             Conv::Msp430Intr => llvm::Msp430Intr,
 380             Conv::PtxKernel => llvm::PtxKernel,
 381             Conv::X86Fastcall => llvm::X86FastcallCallConv,
 382             Conv::X86Intr => llvm::X86_Intr,
 383             Conv::X86Stdcall => llvm::X86StdcallCallConv,
 384             Conv::X86ThisCall => llvm::X86_ThisCall,
 385             Conv::X86VectorCall => llvm::X86_VectorCall,
 386             Conv::X86_64SysV => llvm::X86_64_SysV,
 387             Conv::X86_64Win64 => llvm::X86_64_Win64,
 388         }
 389     }
 390
 391     fn apply_attrs_llfn(&self, cx: &CodegenCx<'ll, 'tcx>, llfn: &'ll Value) {
 392         let mut i = 0;
 393         let mut apply = |attrs: &ArgAttributes, ty: Option<&Type>| {
 394             attrs.apply_llfn(llvm::AttributePlace::Argument(i), llfn, ty);
 395             i += 1;
 396         };
 397         match self.ret.mode {
 398             PassMode::Direct(ref attrs) => {
 399                 attrs.apply_llfn(llvm::AttributePlace::ReturnValue, llfn, None);
 400             }
 401             PassMode::Indirect(ref attrs, _) => apply(attrs, Some(self.ret.layout.llvm_type(cx))),
 402             _ => {}
 403         }
 404         for arg in &self.args {
 405             if arg.pad.is_some() {
 406                 apply(&ArgAttributes::new(), None);
 407             }
 408             match arg.mode {
 409                 PassMode::Ignore => {}
 410                 PassMode::Direct(ref attrs) |
 411                 PassMode::Indirect(ref attrs, None) => apply(attrs, Some(arg.layout.llvm_type(cx))),
 412                 PassMode::Indirect(ref attrs, Some(ref extra_attrs)) => {
 413                     apply(attrs, None);
 414                     apply(extra_attrs, None);
 415                 }
 416                 PassMode::Pair(ref a, ref b) => {
 417                     apply(a, None);
 418                     apply(b, None);
 419                 }
 420                 PassMode::Cast(_) => apply(&ArgAttributes::new(), None),
 421             }
 422         }
 423     }
 424
 425     fn apply_attrs_callsite(&self, bx: &mut Builder<'a, 'll, 'tcx>, callsite: &'ll Value) {
 426         let mut i = 0;
 427         let mut apply = |attrs: &ArgAttributes, ty: Option<&Type>| {
 428             attrs.apply_callsite(llvm::AttributePlace::Argument(i), callsite, ty);
 429             i += 1;
 430         };
 431         match self.ret.mode {
 432             PassMode::Direct(ref attrs) => {
 433                 attrs.apply_callsite(llvm::AttributePlace::ReturnValue, callsite, None);
 434             }
 435             PassMode::Indirect(ref attrs, _) => apply(attrs, Some(self.ret.layout.llvm_type(bx))),
 436             _ => {}
 437         }
 438         if let layout::Abi::Scalar(ref scalar) = self.ret.layout.abi {
 439             // If the value is a boolean, the range is 0..2 and that ultimately
 440             // become 0..0 when the type becomes i1, which would be rejected
 441             // by the LLVM verifier.
 442             if let layout::Int(..) = scalar.value {
 443                 if !scalar.is_bool() {
 444                     let range = scalar.valid_range_exclusive(bx);
 445                     if range.start != range.end {
 446                         bx.range_metadata(callsite, range);
 447                     }
 448                 }
 449             }
 450         }
 451         for arg in &self.args {
 452             if arg.pad.is_some() {
 453                 apply(&ArgAttributes::new(), None);
 454             }
 455             match arg.mode {
 456                 PassMode::Ignore => {}
 457                 PassMode::Direct(ref attrs) |
 458                 PassMode::Indirect(ref attrs, None) => apply(attrs, Some(arg.layout.llvm_type(bx))),
 459                 PassMode::Indirect(ref attrs, Some(ref extra_attrs)) => {
 460                     apply(attrs, None);
 461                     apply(extra_attrs, None);
 462                 }
 463                 PassMode::Pair(ref a, ref b) => {
 464                     apply(a, None);
 465                     apply(b, None);
 466                 }
 467                 PassMode::Cast(_) => apply(&ArgAttributes::new(), None),
 468             }
 469         }
 470
 471         let cconv = self.llvm_cconv();
 472         if cconv != llvm::CCallConv {
 473             llvm::SetInstructionCallConv(callsite, cconv);
 474         }
 475     }
 476 }
 477
 478 impl AbiBuilderMethods<'tcx> for Builder<'a, 'll, 'tcx> {
 479     fn apply_attrs_callsite(
 480         &mut self,
 481         ty: &FnType<'tcx, Ty<'tcx>>,
 482         callsite: Self::Value
 483     ) {
 484         ty.apply_attrs_callsite(self, callsite)
 485     }
 486
 487     fn get_param(&self, index: usize) -> Self::Value {
 488         llvm::get_param(self.llfn(), index as c_uint)
 489     }
 490 }