use crate::abi::{self, Abi, Align, FieldsShape, Size}; use crate::abi::{HasDataLayout, TyAbiInterface, TyAndLayout}; use crate::spec::{self, HasTargetSpec}; use rustc_span::Symbol; use std::fmt; mod aarch64; mod amdgpu; mod arm; mod avr; mod bpf; mod hexagon; mod m68k; mod mips; mod mips64; mod msp430; mod nvptx64; mod powerpc; mod powerpc64; mod riscv; mod s390x; mod sparc; mod sparc64; mod wasm; mod x86; mod x86_64; mod x86_win64; #[derive(PartialEq, Eq, Hash, Debug, HashStable_Generic)] pub enum PassMode { /// Ignore the argument. /// /// The argument is either uninhabited or a ZST. Ignore, /// Pass the argument directly. /// /// The argument has a layout abi of `Scalar`, `Vector` or in rare cases `Aggregate`. Direct(ArgAttributes), /// Pass a pair's elements directly in two arguments. /// /// The argument has a layout abi of `ScalarPair`. Pair(ArgAttributes, ArgAttributes), /// Pass the argument after casting it, to either a single uniform or a /// pair of registers. The bool indicates if a `Reg::i32()` dummy argument /// is emitted before the real argument. Cast(Box, bool), /// Pass the argument indirectly via a hidden pointer. /// The `extra_attrs` value, if any, is for the extra data (vtable or length) /// which indicates that it refers to an unsized rvalue. /// `on_stack` defines that the the value should be passed at a fixed /// stack offset in accordance to the ABI rather than passed using a /// pointer. This corresponds to the `byval` LLVM argument attribute. Indirect { attrs: ArgAttributes, extra_attrs: Option, on_stack: bool }, } // Hack to disable non_upper_case_globals only for the bitflags! and not for the rest // of this module pub use attr_impl::ArgAttribute; #[allow(non_upper_case_globals)] #[allow(unused)] mod attr_impl { // The subset of llvm::Attribute needed for arguments, packed into a bitfield. bitflags::bitflags! { #[derive(Default, HashStable_Generic)] pub struct ArgAttribute: u16 { const NoAlias = 1 << 1; const NoCapture = 1 << 2; const NonNull = 1 << 3; const ReadOnly = 1 << 4; const InReg = 1 << 5; // Due to past miscompiles in LLVM, we use a separate attribute for // &mut arguments, so that the codegen backend can decide whether // or not to actually emit the attribute. It can also be controlled // with the `-Zmutable-noalias` debugging option. const NoAliasMutRef = 1 << 6; const NoUndef = 1 << 7; } } } /// Sometimes an ABI requires small integers to be extended to a full or partial register. This enum /// defines if this extension should be zero-extension or sign-extension when necessary. When it is /// not necessary to extend the argument, this enum is ignored. #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, HashStable_Generic)] pub enum ArgExtension { None, Zext, Sext, } /// A compact representation of LLVM attributes (at least those relevant for this module) /// that can be manipulated without interacting with LLVM's Attribute machinery. #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, HashStable_Generic)] pub struct ArgAttributes { pub regular: ArgAttribute, pub arg_ext: ArgExtension, /// The minimum size of the pointee, guaranteed to be valid for the duration of the whole call /// (corresponding to LLVM's dereferenceable and dereferenceable_or_null attributes). pub pointee_size: Size, pub pointee_align: Option, } impl ArgAttributes { pub fn new() -> Self { ArgAttributes { regular: ArgAttribute::default(), arg_ext: ArgExtension::None, pointee_size: Size::ZERO, pointee_align: None, } } pub fn ext(&mut self, ext: ArgExtension) -> &mut Self { assert!( self.arg_ext == ArgExtension::None || self.arg_ext == ext, "cannot set {:?} when {:?} is already set", ext, self.arg_ext ); self.arg_ext = ext; self } pub fn set(&mut self, attr: ArgAttribute) -> &mut Self { self.regular |= attr; self } pub fn contains(&self, attr: ArgAttribute) -> bool { self.regular.contains(attr) } } #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, HashStable_Generic)] pub enum RegKind { Integer, Float, Vector, } #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, HashStable_Generic)] pub struct Reg { pub kind: RegKind, pub size: Size, } macro_rules! reg_ctor { ($name:ident, $kind:ident, $bits:expr) => { pub fn $name() -> Reg { Reg { kind: RegKind::$kind, size: Size::from_bits($bits) } } }; } impl Reg { reg_ctor!(i8, Integer, 8); reg_ctor!(i16, Integer, 16); reg_ctor!(i32, Integer, 32); reg_ctor!(i64, Integer, 64); reg_ctor!(i128, Integer, 128); reg_ctor!(f32, Float, 32); reg_ctor!(f64, Float, 64); } impl Reg { pub fn align(&self, cx: &C) -> Align { let dl = cx.data_layout(); match self.kind { RegKind::Integer => match self.size.bits() { 1 => dl.i1_align.abi, 2..=8 => dl.i8_align.abi, 9..=16 => dl.i16_align.abi, 17..=32 => dl.i32_align.abi, 33..=64 => dl.i64_align.abi, 65..=128 => dl.i128_align.abi, _ => panic!("unsupported integer: {:?}", self), }, RegKind::Float => match self.size.bits() { 32 => dl.f32_align.abi, 64 => dl.f64_align.abi, _ => panic!("unsupported float: {:?}", self), }, RegKind::Vector => dl.vector_align(self.size).abi, } } } /// An argument passed entirely registers with the /// same kind (e.g., HFA / HVA on PPC64 and AArch64). #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, HashStable_Generic)] pub struct Uniform { pub unit: Reg, /// The total size of the argument, which can be: /// * equal to `unit.size` (one scalar/vector), /// * a multiple of `unit.size` (an array of scalar/vectors), /// * if `unit.kind` is `Integer`, the last element /// can be shorter, i.e., `{ i64, i64, i32 }` for /// 64-bit integers with a total size of 20 bytes. pub total: Size, } impl From for Uniform { fn from(unit: Reg) -> Uniform { Uniform { unit, total: unit.size } } } impl Uniform { pub fn align(&self, cx: &C) -> Align { self.unit.align(cx) } } #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, HashStable_Generic)] pub struct CastTarget { pub prefix: [Option; 8], pub rest: Uniform, pub attrs: ArgAttributes, } impl From for CastTarget { fn from(unit: Reg) -> CastTarget { CastTarget::from(Uniform::from(unit)) } } impl From for CastTarget { fn from(uniform: Uniform) -> CastTarget { CastTarget { prefix: [None; 8], rest: uniform, attrs: ArgAttributes { regular: ArgAttribute::default(), arg_ext: ArgExtension::None, pointee_size: Size::ZERO, pointee_align: None, }, } } } impl CastTarget { pub fn pair(a: Reg, b: Reg) -> CastTarget { CastTarget { prefix: [Some(a), None, None, None, None, None, None, None], rest: Uniform::from(b), attrs: ArgAttributes { regular: ArgAttribute::default(), arg_ext: ArgExtension::None, pointee_size: Size::ZERO, pointee_align: None, }, } } pub fn size(&self, _cx: &C) -> Size { let mut size = self.rest.total; for i in 0..self.prefix.iter().count() { match self.prefix[i] { Some(v) => size += Size { raw: v.size.bytes() }, None => {} } } return size; } pub fn align(&self, cx: &C) -> Align { self.prefix .iter() .filter_map(|x| x.map(|reg| reg.align(cx))) .fold(cx.data_layout().aggregate_align.abi.max(self.rest.align(cx)), |acc, align| { acc.max(align) }) } } /// Return value from the `homogeneous_aggregate` test function. #[derive(Copy, Clone, Debug)] pub enum HomogeneousAggregate { /// Yes, all the "leaf fields" of this struct are passed in the /// same way (specified in the `Reg` value). Homogeneous(Reg), /// There are no leaf fields at all. NoData, } /// Error from the `homogeneous_aggregate` test function, indicating /// there are distinct leaf fields passed in different ways, /// or this is uninhabited. #[derive(Copy, Clone, Debug)] pub struct Heterogeneous; impl HomogeneousAggregate { /// If this is a homogeneous aggregate, returns the homogeneous /// unit, else `None`. pub fn unit(self) -> Option { match self { HomogeneousAggregate::Homogeneous(reg) => Some(reg), HomogeneousAggregate::NoData => None, } } /// Try to combine two `HomogeneousAggregate`s, e.g. from two fields in /// the same `struct`. Only succeeds if only one of them has any data, /// or both units are identical. fn merge(self, other: HomogeneousAggregate) -> Result { match (self, other) { (x, HomogeneousAggregate::NoData) | (HomogeneousAggregate::NoData, x) => Ok(x), (HomogeneousAggregate::Homogeneous(a), HomogeneousAggregate::Homogeneous(b)) => { if a != b { return Err(Heterogeneous); } Ok(self) } } } } impl<'a, Ty> TyAndLayout<'a, Ty> { fn is_aggregate(&self) -> bool { match self.abi { Abi::Uninhabited | Abi::Scalar(_) | Abi::Vector { .. } => false, Abi::ScalarPair(..) | Abi::Aggregate { .. } => true, } } /// Returns `Homogeneous` if this layout is an aggregate containing fields of /// only a single type (e.g., `(u32, u32)`). Such aggregates are often /// special-cased in ABIs. /// /// Note: We generally ignore fields of zero-sized type when computing /// this value (see #56877). /// /// This is public so that it can be used in unit tests, but /// should generally only be relevant to the ABI details of /// specific targets. pub fn homogeneous_aggregate(&self, cx: &C) -> Result where Ty: TyAbiInterface<'a, C> + Copy, { match self.abi { Abi::Uninhabited => Err(Heterogeneous), // The primitive for this algorithm. Abi::Scalar(scalar) => { let kind = match scalar.primitive() { abi::Int(..) | abi::Pointer => RegKind::Integer, abi::F32 | abi::F64 => RegKind::Float, }; Ok(HomogeneousAggregate::Homogeneous(Reg { kind, size: self.size })) } Abi::Vector { .. } => { assert!(!self.is_zst()); Ok(HomogeneousAggregate::Homogeneous(Reg { kind: RegKind::Vector, size: self.size, })) } Abi::ScalarPair(..) | Abi::Aggregate { .. } => { // Helper for computing `homogeneous_aggregate`, allowing a custom // starting offset (used below for handling variants). let from_fields_at = |layout: Self, start: Size| -> Result<(HomogeneousAggregate, Size), Heterogeneous> { let is_union = match layout.fields { FieldsShape::Primitive => { unreachable!("aggregates can't have `FieldsShape::Primitive`") } FieldsShape::Array { count, .. } => { assert_eq!(start, Size::ZERO); let result = if count > 0 { layout.field(cx, 0).homogeneous_aggregate(cx)? } else { HomogeneousAggregate::NoData }; return Ok((result, layout.size)); } FieldsShape::Union(_) => true, FieldsShape::Arbitrary { .. } => false, }; let mut result = HomogeneousAggregate::NoData; let mut total = start; for i in 0..layout.fields.count() { if !is_union && total != layout.fields.offset(i) { return Err(Heterogeneous); } let field = layout.field(cx, i); result = result.merge(field.homogeneous_aggregate(cx)?)?; // Keep track of the offset (without padding). let size = field.size; if is_union { total = total.max(size); } else { total += size; } } Ok((result, total)) }; let (mut result, mut total) = from_fields_at(*self, Size::ZERO)?; match &self.variants { abi::Variants::Single { .. } => {} abi::Variants::Multiple { variants, .. } => { // Treat enum variants like union members. // HACK(eddyb) pretend the `enum` field (discriminant) // is at the start of every variant (otherwise the gap // at the start of all variants would disqualify them). // // NB: for all tagged `enum`s (which include all non-C-like // `enum`s with defined FFI representation), this will // match the homogeneous computation on the equivalent // `struct { tag; union { variant1; ... } }` and/or // `union { struct { tag; variant1; } ... }` // (the offsets of variant fields should be identical // between the two for either to be a homogeneous aggregate). let variant_start = total; for variant_idx in variants.indices() { let (variant_result, variant_total) = from_fields_at(self.for_variant(cx, variant_idx), variant_start)?; result = result.merge(variant_result)?; total = total.max(variant_total); } } } // There needs to be no padding. if total != self.size { Err(Heterogeneous) } else { match result { HomogeneousAggregate::Homogeneous(_) => { assert_ne!(total, Size::ZERO); } HomogeneousAggregate::NoData => { assert_eq!(total, Size::ZERO); } } Ok(result) } } } } } /// Information about how to pass an argument to, /// or return a value from, a function, under some ABI. #[derive(PartialEq, Eq, Hash, Debug, HashStable_Generic)] pub struct ArgAbi<'a, Ty> { pub layout: TyAndLayout<'a, Ty>, pub mode: PassMode, } impl<'a, Ty> ArgAbi<'a, Ty> { pub fn new( cx: &impl HasDataLayout, layout: TyAndLayout<'a, Ty>, scalar_attrs: impl Fn(&TyAndLayout<'a, Ty>, abi::Scalar, Size) -> ArgAttributes, ) -> Self { let mode = match layout.abi { Abi::Uninhabited => PassMode::Ignore, Abi::Scalar(scalar) => PassMode::Direct(scalar_attrs(&layout, scalar, Size::ZERO)), Abi::ScalarPair(a, b) => PassMode::Pair( scalar_attrs(&layout, a, Size::ZERO), scalar_attrs(&layout, b, a.size(cx).align_to(b.align(cx).abi)), ), Abi::Vector { .. } => PassMode::Direct(ArgAttributes::new()), Abi::Aggregate { .. } => PassMode::Direct(ArgAttributes::new()), }; ArgAbi { layout, mode } } fn indirect_pass_mode(layout: &TyAndLayout<'a, Ty>) -> PassMode { let mut attrs = ArgAttributes::new(); // For non-immediate arguments the callee gets its own copy of // the value on the stack, so there are no aliases. It's also // program-invisible so can't possibly capture attrs .set(ArgAttribute::NoAlias) .set(ArgAttribute::NoCapture) .set(ArgAttribute::NonNull) .set(ArgAttribute::NoUndef); attrs.pointee_size = layout.size; // FIXME(eddyb) We should be doing this, but at least on // i686-pc-windows-msvc, it results in wrong stack offsets. // attrs.pointee_align = Some(layout.align.abi); let extra_attrs = layout.is_unsized().then_some(ArgAttributes::new()); PassMode::Indirect { attrs, extra_attrs, on_stack: false } } pub fn make_indirect(&mut self) { match self.mode { PassMode::Direct(_) | PassMode::Pair(_, _) => {} PassMode::Indirect { attrs: _, extra_attrs: None, on_stack: false } => return, _ => panic!("Tried to make {:?} indirect", self.mode), } self.mode = Self::indirect_pass_mode(&self.layout); } pub fn make_indirect_byval(&mut self) { self.make_indirect(); match self.mode { PassMode::Indirect { attrs: _, extra_attrs: _, ref mut on_stack } => { *on_stack = true; } _ => unreachable!(), } } pub fn extend_integer_width_to(&mut self, bits: u64) { // Only integers have signedness if let Abi::Scalar(scalar) = self.layout.abi { if let abi::Int(i, signed) = scalar.primitive() { if i.size().bits() < bits { if let PassMode::Direct(ref mut attrs) = self.mode { if signed { attrs.ext(ArgExtension::Sext) } else { attrs.ext(ArgExtension::Zext) }; } } } } } pub fn cast_to>(&mut self, target: T) { self.mode = PassMode::Cast(Box::new(target.into()), false); } pub fn cast_to_and_pad_i32>(&mut self, target: T, pad_i32: bool) { self.mode = PassMode::Cast(Box::new(target.into()), pad_i32); } pub fn is_indirect(&self) -> bool { matches!(self.mode, PassMode::Indirect { .. }) } pub fn is_sized_indirect(&self) -> bool { matches!(self.mode, PassMode::Indirect { attrs: _, extra_attrs: None, on_stack: _ }) } pub fn is_unsized_indirect(&self) -> bool { matches!(self.mode, PassMode::Indirect { attrs: _, extra_attrs: Some(_), on_stack: _ }) } pub fn is_ignore(&self) -> bool { matches!(self.mode, PassMode::Ignore) } } #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, HashStable_Generic)] pub enum Conv { // General language calling conventions, for which every target // should have its own backend (e.g. LLVM) support. C, Rust, /// For things unlikely to be called, where smaller caller codegen is /// preferred over raw speed. /// Stronger than just `#[cold]` because `fn` pointers might be incompatible. RustCold, // Target-specific calling conventions. ArmAapcs, CCmseNonSecureCall, Msp430Intr, PtxKernel, X86Fastcall, X86Intr, X86Stdcall, X86ThisCall, X86VectorCall, X86_64SysV, X86_64Win64, AmdGpuKernel, AvrInterrupt, AvrNonBlockingInterrupt, } /// Metadata describing how the arguments to a native function /// should be passed in order to respect the native ABI. /// /// I will do my best to describe this structure, but these /// comments are reverse-engineered and may be inaccurate. -NDM #[derive(PartialEq, Eq, Hash, Debug, HashStable_Generic)] pub struct FnAbi<'a, Ty> { /// The LLVM types of each argument. pub args: Box<[ArgAbi<'a, Ty>]>, /// LLVM return type. pub ret: ArgAbi<'a, Ty>, pub c_variadic: bool, /// The count of non-variadic arguments. /// /// Should only be different from args.len() when c_variadic is true. /// This can be used to know whether an argument is variadic or not. pub fixed_count: u32, pub conv: Conv, pub can_unwind: bool, } /// Error produced by attempting to adjust a `FnAbi`, for a "foreign" ABI. #[derive(Copy, Clone, Debug, HashStable_Generic)] pub enum AdjustForForeignAbiError { /// Target architecture doesn't support "foreign" (i.e. non-Rust) ABIs. Unsupported { arch: Symbol, abi: spec::abi::Abi }, } impl fmt::Display for AdjustForForeignAbiError { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { match self { Self::Unsupported { arch, abi } => { write!(f, "target architecture {:?} does not support `extern {}` ABI", arch, abi) } } } } impl<'a, Ty> FnAbi<'a, Ty> { pub fn adjust_for_foreign_abi( &mut self, cx: &C, abi: spec::abi::Abi, ) -> Result<(), AdjustForForeignAbiError> where Ty: TyAbiInterface<'a, C> + Copy, C: HasDataLayout + HasTargetSpec, { if abi == spec::abi::Abi::X86Interrupt { if let Some(arg) = self.args.first_mut() { arg.make_indirect_byval(); } return Ok(()); } match &cx.target_spec().arch[..] { "x86" => { let flavor = if let spec::abi::Abi::Fastcall { .. } | spec::abi::Abi::Vectorcall { .. } = abi { x86::Flavor::FastcallOrVectorcall } else { x86::Flavor::General }; x86::compute_abi_info(cx, self, flavor); } "x86_64" => match abi { spec::abi::Abi::SysV64 { .. } => x86_64::compute_abi_info(cx, self), spec::abi::Abi::Win64 { .. } => x86_win64::compute_abi_info(self), _ => { if cx.target_spec().is_like_windows { x86_win64::compute_abi_info(self) } else { x86_64::compute_abi_info(cx, self) } } }, "aarch64" => { let param_policy = if cx.target_spec().is_like_osx { aarch64::ParamExtension::ExtendTo32Bits } else { aarch64::ParamExtension::NoExtension }; aarch64::compute_abi_info(cx, self, param_policy) } "amdgpu" => amdgpu::compute_abi_info(cx, self), "arm" => arm::compute_abi_info(cx, self), "avr" => avr::compute_abi_info(self), "m68k" => m68k::compute_abi_info(self), "mips" => mips::compute_abi_info(cx, self), "mips64" => mips64::compute_abi_info(cx, self), "powerpc" => powerpc::compute_abi_info(self), "powerpc64" => powerpc64::compute_abi_info(cx, self), "s390x" => s390x::compute_abi_info(cx, self), "msp430" => msp430::compute_abi_info(self), "sparc" => sparc::compute_abi_info(cx, self), "sparc64" => sparc64::compute_abi_info(cx, self), "nvptx64" => { if cx.target_spec().adjust_abi(abi) == spec::abi::Abi::PtxKernel { nvptx64::compute_ptx_kernel_abi_info(cx, self) } else { nvptx64::compute_abi_info(self) } } "hexagon" => hexagon::compute_abi_info(self), "riscv32" | "riscv64" => riscv::compute_abi_info(cx, self), "wasm32" | "wasm64" => { if cx.target_spec().adjust_abi(abi) == spec::abi::Abi::Wasm { wasm::compute_wasm_abi_info(self) } else { wasm::compute_c_abi_info(cx, self) } } "asmjs" => wasm::compute_c_abi_info(cx, self), "bpf" => bpf::compute_abi_info(self), arch => { return Err(AdjustForForeignAbiError::Unsupported { arch: Symbol::intern(arch), abi, }); } } Ok(()) } } // Some types are used a lot. Make sure they don't unintentionally get bigger. #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))] mod size_asserts { use super::*; use rustc_data_structures::static_assert_size; // These are in alphabetical order, which is easy to maintain. static_assert_size!(ArgAbi<'_, usize>, 56); static_assert_size!(FnAbi<'_, usize>, 80); }