| use super::place::PlaceRef; |
| use super::{FunctionCx, LocalRef}; |
| |
| use crate::base; |
| use crate::common::TypeKind; |
| use crate::glue; |
| use crate::traits::*; |
| use crate::MemFlags; |
| |
| use rustc_middle::mir; |
| use rustc_middle::mir::interpret::{ConstValue, Pointer, Scalar}; |
| use rustc_middle::ty::layout::{LayoutOf, TyAndLayout}; |
| use rustc_middle::ty::Ty; |
| use rustc_target::abi::{Abi, Align, Size}; |
| |
| use std::fmt; |
| |
| /// The representation of a Rust value. The enum variant is in fact |
| /// uniquely determined by the value's type, but is kept as a |
| /// safety check. |
| #[derive(Copy, Clone, Debug)] |
| pub enum OperandValue<V> { |
| /// A reference to the actual operand. The data is guaranteed |
| /// to be valid for the operand's lifetime. |
| /// The second value, if any, is the extra data (vtable or length) |
| /// which indicates that it refers to an unsized rvalue. |
| /// |
| /// An `OperandValue` has this variant for types which are neither |
| /// `Immediate` nor `Pair`s. The backend value in this variant must be a |
| /// pointer to the *non*-immediate backend type. That pointee type is the |
| /// one returned by [`LayoutTypeMethods::backend_type`]. |
| Ref(V, Option<V>, Align), |
| /// A single LLVM immediate value. |
| /// |
| /// An `OperandValue` *must* be this variant for any type for which |
| /// [`LayoutTypeMethods::is_backend_immediate`] returns `true`. |
| /// The backend value in this variant must be the *immediate* backend type, |
| /// as returned by [`LayoutTypeMethods::immediate_backend_type`]. |
| Immediate(V), |
| /// A pair of immediate LLVM values. Used by fat pointers too. |
| /// |
| /// An `OperandValue` *must* be this variant for any type for which |
| /// [`LayoutTypeMethods::is_backend_scalar_pair`] returns `true`. |
| /// The backend values in this variant must be the *immediate* backend types, |
| /// as returned by [`LayoutTypeMethods::scalar_pair_element_backend_type`] |
| /// with `immediate: true`. |
| Pair(V, V), |
| } |
| |
| /// An `OperandRef` is an "SSA" reference to a Rust value, along with |
| /// its type. |
| /// |
| /// NOTE: unless you know a value's type exactly, you should not |
| /// generate LLVM opcodes acting on it and instead act via methods, |
| /// to avoid nasty edge cases. In particular, using `Builder::store` |
| /// directly is sure to cause problems -- use `OperandRef::store` |
| /// instead. |
| #[derive(Copy, Clone)] |
| pub struct OperandRef<'tcx, V> { |
| /// The value. |
| pub val: OperandValue<V>, |
| |
| /// The layout of value, based on its Rust type. |
| pub layout: TyAndLayout<'tcx>, |
| } |
| |
| impl<V: CodegenObject> fmt::Debug for OperandRef<'_, V> { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| write!(f, "OperandRef({:?} @ {:?})", self.val, self.layout) |
| } |
| } |
| |
| impl<'a, 'tcx, V: CodegenObject> OperandRef<'tcx, V> { |
| pub fn new_zst<Bx: BuilderMethods<'a, 'tcx, Value = V>>( |
| bx: &mut Bx, |
| layout: TyAndLayout<'tcx>, |
| ) -> OperandRef<'tcx, V> { |
| assert!(layout.is_zst()); |
| OperandRef { |
| val: OperandValue::Immediate(bx.const_poison(bx.immediate_backend_type(layout))), |
| layout, |
| } |
| } |
| |
| pub fn from_const<Bx: BuilderMethods<'a, 'tcx, Value = V>>( |
| bx: &mut Bx, |
| val: ConstValue<'tcx>, |
| ty: Ty<'tcx>, |
| ) -> Self { |
| let layout = bx.layout_of(ty); |
| |
| let val = match val { |
| ConstValue::Scalar(x) => { |
| let Abi::Scalar(scalar) = layout.abi else { |
| bug!("from_const: invalid ByVal layout: {:#?}", layout); |
| }; |
| let llval = bx.scalar_to_backend(x, scalar, bx.immediate_backend_type(layout)); |
| OperandValue::Immediate(llval) |
| } |
| ConstValue::ZeroSized => return OperandRef::new_zst(bx, layout), |
| ConstValue::Slice { data, start, end } => { |
| let Abi::ScalarPair(a_scalar, _) = layout.abi else { |
| bug!("from_const: invalid ScalarPair layout: {:#?}", layout); |
| }; |
| let a = Scalar::from_pointer( |
| Pointer::new(bx.tcx().create_memory_alloc(data), Size::from_bytes(start)), |
| &bx.tcx(), |
| ); |
| let a_llval = bx.scalar_to_backend( |
| a, |
| a_scalar, |
| bx.scalar_pair_element_backend_type(layout, 0, true), |
| ); |
| let b_llval = bx.const_usize((end - start) as u64); |
| OperandValue::Pair(a_llval, b_llval) |
| } |
| ConstValue::ByRef { alloc, offset } => { |
| return bx.load_operand(bx.from_const_alloc(layout, alloc, offset)); |
| } |
| }; |
| |
| OperandRef { val, layout } |
| } |
| |
| /// Asserts that this operand refers to a scalar and returns |
| /// a reference to its value. |
| pub fn immediate(self) -> V { |
| match self.val { |
| OperandValue::Immediate(s) => s, |
| _ => bug!("not immediate: {:?}", self), |
| } |
| } |
| |
| pub fn deref<Cx: LayoutTypeMethods<'tcx>>(self, cx: &Cx) -> PlaceRef<'tcx, V> { |
| if self.layout.ty.is_box() { |
| bug!("dereferencing {:?} in codegen", self.layout.ty); |
| } |
| |
| let projected_ty = self |
| .layout |
| .ty |
| .builtin_deref(true) |
| .unwrap_or_else(|| bug!("deref of non-pointer {:?}", self)) |
| .ty; |
| |
| let (llptr, llextra) = match self.val { |
| OperandValue::Immediate(llptr) => (llptr, None), |
| OperandValue::Pair(llptr, llextra) => (llptr, Some(llextra)), |
| OperandValue::Ref(..) => bug!("Deref of by-Ref operand {:?}", self), |
| }; |
| let layout = cx.layout_of(projected_ty); |
| PlaceRef { llval: llptr, llextra, layout, align: layout.align.abi } |
| } |
| |
| /// If this operand is a `Pair`, we return an aggregate with the two values. |
| /// For other cases, see `immediate`. |
| pub fn immediate_or_packed_pair<Bx: BuilderMethods<'a, 'tcx, Value = V>>( |
| self, |
| bx: &mut Bx, |
| ) -> V { |
| if let OperandValue::Pair(a, b) = self.val { |
| let llty = bx.cx().backend_type(self.layout); |
| debug!("Operand::immediate_or_packed_pair: packing {:?} into {:?}", self, llty); |
| // Reconstruct the immediate aggregate. |
| let mut llpair = bx.cx().const_poison(llty); |
| let imm_a = bx.from_immediate(a); |
| let imm_b = bx.from_immediate(b); |
| llpair = bx.insert_value(llpair, imm_a, 0); |
| llpair = bx.insert_value(llpair, imm_b, 1); |
| llpair |
| } else { |
| self.immediate() |
| } |
| } |
| |
| /// If the type is a pair, we return a `Pair`, otherwise, an `Immediate`. |
| pub fn from_immediate_or_packed_pair<Bx: BuilderMethods<'a, 'tcx, Value = V>>( |
| bx: &mut Bx, |
| llval: V, |
| layout: TyAndLayout<'tcx>, |
| ) -> Self { |
| let val = if let Abi::ScalarPair(a, b) = layout.abi { |
| debug!("Operand::from_immediate_or_packed_pair: unpacking {:?} @ {:?}", llval, layout); |
| |
| // Deconstruct the immediate aggregate. |
| let a_llval = bx.extract_value(llval, 0); |
| let a_llval = bx.to_immediate_scalar(a_llval, a); |
| let b_llval = bx.extract_value(llval, 1); |
| let b_llval = bx.to_immediate_scalar(b_llval, b); |
| OperandValue::Pair(a_llval, b_llval) |
| } else { |
| OperandValue::Immediate(llval) |
| }; |
| OperandRef { val, layout } |
| } |
| |
| pub fn extract_field<Bx: BuilderMethods<'a, 'tcx, Value = V>>( |
| &self, |
| bx: &mut Bx, |
| i: usize, |
| ) -> Self { |
| let field = self.layout.field(bx.cx(), i); |
| let offset = self.layout.fields.offset(i); |
| |
| let mut val = match (self.val, self.layout.abi) { |
| // If the field is ZST, it has no data. |
| _ if field.is_zst() => { |
| return OperandRef::new_zst(bx, field); |
| } |
| |
| // Newtype of a scalar, scalar pair or vector. |
| (OperandValue::Immediate(_) | OperandValue::Pair(..), _) |
| if field.size == self.layout.size => |
| { |
| assert_eq!(offset.bytes(), 0); |
| self.val |
| } |
| |
| // Extract a scalar component from a pair. |
| (OperandValue::Pair(a_llval, b_llval), Abi::ScalarPair(a, b)) => { |
| if offset.bytes() == 0 { |
| assert_eq!(field.size, a.size(bx.cx())); |
| OperandValue::Immediate(a_llval) |
| } else { |
| assert_eq!(offset, a.size(bx.cx()).align_to(b.align(bx.cx()).abi)); |
| assert_eq!(field.size, b.size(bx.cx())); |
| OperandValue::Immediate(b_llval) |
| } |
| } |
| |
| // `#[repr(simd)]` types are also immediate. |
| (OperandValue::Immediate(llval), Abi::Vector { .. }) => { |
| OperandValue::Immediate(bx.extract_element(llval, bx.cx().const_usize(i as u64))) |
| } |
| |
| _ => bug!("OperandRef::extract_field({:?}): not applicable", self), |
| }; |
| |
| match (&mut val, field.abi) { |
| ( |
| OperandValue::Immediate(llval), |
| Abi::Scalar(_) | Abi::ScalarPair(..) | Abi::Vector { .. }, |
| ) => { |
| // Bools in union fields needs to be truncated. |
| *llval = bx.to_immediate(*llval, field); |
| // HACK(eddyb) have to bitcast pointers until LLVM removes pointee types. |
| let ty = bx.cx().immediate_backend_type(field); |
| if bx.type_kind(ty) == TypeKind::Pointer { |
| *llval = bx.pointercast(*llval, ty); |
| } |
| } |
| (OperandValue::Pair(a, b), Abi::ScalarPair(a_abi, b_abi)) => { |
| // Bools in union fields needs to be truncated. |
| *a = bx.to_immediate_scalar(*a, a_abi); |
| *b = bx.to_immediate_scalar(*b, b_abi); |
| // HACK(eddyb) have to bitcast pointers until LLVM removes pointee types. |
| let a_ty = bx.cx().scalar_pair_element_backend_type(field, 0, true); |
| let b_ty = bx.cx().scalar_pair_element_backend_type(field, 1, true); |
| if bx.type_kind(a_ty) == TypeKind::Pointer { |
| *a = bx.pointercast(*a, a_ty); |
| } |
| if bx.type_kind(b_ty) == TypeKind::Pointer { |
| *b = bx.pointercast(*b, b_ty); |
| } |
| } |
| // Newtype vector of array, e.g. #[repr(simd)] struct S([i32; 4]); |
| (OperandValue::Immediate(llval), Abi::Aggregate { sized: true }) => { |
| assert!(matches!(self.layout.abi, Abi::Vector { .. })); |
| |
| let llty = bx.cx().backend_type(self.layout); |
| let llfield_ty = bx.cx().backend_type(field); |
| |
| // Can't bitcast an aggregate, so round trip through memory. |
| let lltemp = bx.alloca(llfield_ty, field.align.abi); |
| let llptr = bx.pointercast(lltemp, bx.cx().type_ptr_to(llty)); |
| bx.store(*llval, llptr, field.align.abi); |
| *llval = bx.load(llfield_ty, lltemp, field.align.abi); |
| } |
| (OperandValue::Immediate(_), Abi::Uninhabited | Abi::Aggregate { sized: false }) => { |
| bug!() |
| } |
| (OperandValue::Pair(..), _) => bug!(), |
| (OperandValue::Ref(..), _) => bug!(), |
| } |
| |
| OperandRef { val, layout: field } |
| } |
| } |
| |
| impl<'a, 'tcx, V: CodegenObject> OperandValue<V> { |
| /// Returns an `OperandValue` that's generally UB to use in any way. |
| /// |
| /// Depending on the `layout`, returns an `Immediate` or `Pair` containing |
| /// poison value(s), or a `Ref` containing a poison pointer. |
| /// |
| /// Supports sized types only. |
| pub fn poison<Bx: BuilderMethods<'a, 'tcx, Value = V>>( |
| bx: &mut Bx, |
| layout: TyAndLayout<'tcx>, |
| ) -> OperandValue<V> { |
| assert!(layout.is_sized()); |
| if bx.cx().is_backend_immediate(layout) { |
| let ibty = bx.cx().immediate_backend_type(layout); |
| OperandValue::Immediate(bx.const_poison(ibty)) |
| } else if bx.cx().is_backend_scalar_pair(layout) { |
| let ibty0 = bx.cx().scalar_pair_element_backend_type(layout, 0, true); |
| let ibty1 = bx.cx().scalar_pair_element_backend_type(layout, 1, true); |
| OperandValue::Pair(bx.const_poison(ibty0), bx.const_poison(ibty1)) |
| } else { |
| let bty = bx.cx().backend_type(layout); |
| let ptr_bty = bx.cx().type_ptr_to(bty); |
| OperandValue::Ref(bx.const_poison(ptr_bty), None, layout.align.abi) |
| } |
| } |
| |
| pub fn store<Bx: BuilderMethods<'a, 'tcx, Value = V>>( |
| self, |
| bx: &mut Bx, |
| dest: PlaceRef<'tcx, V>, |
| ) { |
| self.store_with_flags(bx, dest, MemFlags::empty()); |
| } |
| |
| pub fn volatile_store<Bx: BuilderMethods<'a, 'tcx, Value = V>>( |
| self, |
| bx: &mut Bx, |
| dest: PlaceRef<'tcx, V>, |
| ) { |
| self.store_with_flags(bx, dest, MemFlags::VOLATILE); |
| } |
| |
| pub fn unaligned_volatile_store<Bx: BuilderMethods<'a, 'tcx, Value = V>>( |
| self, |
| bx: &mut Bx, |
| dest: PlaceRef<'tcx, V>, |
| ) { |
| self.store_with_flags(bx, dest, MemFlags::VOLATILE | MemFlags::UNALIGNED); |
| } |
| |
| pub fn nontemporal_store<Bx: BuilderMethods<'a, 'tcx, Value = V>>( |
| self, |
| bx: &mut Bx, |
| dest: PlaceRef<'tcx, V>, |
| ) { |
| self.store_with_flags(bx, dest, MemFlags::NONTEMPORAL); |
| } |
| |
| fn store_with_flags<Bx: BuilderMethods<'a, 'tcx, Value = V>>( |
| self, |
| bx: &mut Bx, |
| dest: PlaceRef<'tcx, V>, |
| flags: MemFlags, |
| ) { |
| debug!("OperandRef::store: operand={:?}, dest={:?}", self, dest); |
| // Avoid generating stores of zero-sized values, because the only way to have a zero-sized |
| // value is through `undef`, and store itself is useless. |
| if dest.layout.is_zst() { |
| return; |
| } |
| match self { |
| OperandValue::Ref(r, None, source_align) => { |
| if flags.contains(MemFlags::NONTEMPORAL) { |
| // HACK(nox): This is inefficient but there is no nontemporal memcpy. |
| let ty = bx.backend_type(dest.layout); |
| let ptr = bx.pointercast(r, bx.type_ptr_to(ty)); |
| let val = bx.load(ty, ptr, source_align); |
| bx.store_with_flags(val, dest.llval, dest.align, flags); |
| return; |
| } |
| base::memcpy_ty(bx, dest.llval, dest.align, r, source_align, dest.layout, flags) |
| } |
| OperandValue::Ref(_, Some(_), _) => { |
| bug!("cannot directly store unsized values"); |
| } |
| OperandValue::Immediate(s) => { |
| let val = bx.from_immediate(s); |
| bx.store_with_flags(val, dest.llval, dest.align, flags); |
| } |
| OperandValue::Pair(a, b) => { |
| let Abi::ScalarPair(a_scalar, b_scalar) = dest.layout.abi else { |
| bug!("store_with_flags: invalid ScalarPair layout: {:#?}", dest.layout); |
| }; |
| let ty = bx.backend_type(dest.layout); |
| let b_offset = a_scalar.size(bx).align_to(b_scalar.align(bx).abi); |
| |
| let llptr = bx.struct_gep(ty, dest.llval, 0); |
| let val = bx.from_immediate(a); |
| let align = dest.align; |
| bx.store_with_flags(val, llptr, align, flags); |
| |
| let llptr = bx.struct_gep(ty, dest.llval, 1); |
| let val = bx.from_immediate(b); |
| let align = dest.align.restrict_for_offset(b_offset); |
| bx.store_with_flags(val, llptr, align, flags); |
| } |
| } |
| } |
| |
| pub fn store_unsized<Bx: BuilderMethods<'a, 'tcx, Value = V>>( |
| self, |
| bx: &mut Bx, |
| indirect_dest: PlaceRef<'tcx, V>, |
| ) { |
| debug!("OperandRef::store_unsized: operand={:?}, indirect_dest={:?}", self, indirect_dest); |
| // `indirect_dest` must have `*mut T` type. We extract `T` out of it. |
| let unsized_ty = indirect_dest |
| .layout |
| .ty |
| .builtin_deref(true) |
| .unwrap_or_else(|| bug!("indirect_dest has non-pointer type: {:?}", indirect_dest)) |
| .ty; |
| |
| let OperandValue::Ref(llptr, Some(llextra), _) = self else { |
| bug!("store_unsized called with a sized value") |
| }; |
| |
| // Allocate an appropriate region on the stack, and copy the value into it. Since alloca |
| // doesn't support dynamic alignment, we allocate an extra align - 1 bytes, and align the |
| // pointer manually. |
| let (size, align) = glue::size_and_align_of_dst(bx, unsized_ty, Some(llextra)); |
| let one = bx.const_usize(1); |
| let align_minus_1 = bx.sub(align, one); |
| let size_extra = bx.add(size, align_minus_1); |
| let min_align = Align::ONE; |
| let alloca = bx.byte_array_alloca(size_extra, min_align); |
| let address = bx.ptrtoint(alloca, bx.type_isize()); |
| let neg_address = bx.neg(address); |
| let offset = bx.and(neg_address, align_minus_1); |
| let dst = bx.inbounds_gep(bx.type_i8(), alloca, &[offset]); |
| bx.memcpy(dst, min_align, llptr, min_align, size, MemFlags::empty()); |
| |
| // Store the allocated region and the extra to the indirect place. |
| let indirect_operand = OperandValue::Pair(dst, llextra); |
| indirect_operand.store(bx, indirect_dest); |
| } |
| } |
| |
| impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { |
| fn maybe_codegen_consume_direct( |
| &mut self, |
| bx: &mut Bx, |
| place_ref: mir::PlaceRef<'tcx>, |
| ) -> Option<OperandRef<'tcx, Bx::Value>> { |
| debug!("maybe_codegen_consume_direct(place_ref={:?})", place_ref); |
| |
| match self.locals[place_ref.local] { |
| LocalRef::Operand(mut o) => { |
| // Moves out of scalar and scalar pair fields are trivial. |
| for elem in place_ref.projection.iter() { |
| match elem { |
| mir::ProjectionElem::Field(ref f, _) => { |
| o = o.extract_field(bx, f.index()); |
| } |
| mir::ProjectionElem::Index(_) |
| | mir::ProjectionElem::ConstantIndex { .. } => { |
| // ZSTs don't require any actual memory access. |
| // FIXME(eddyb) deduplicate this with the identical |
| // checks in `codegen_consume` and `extract_field`. |
| let elem = o.layout.field(bx.cx(), 0); |
| if elem.is_zst() { |
| o = OperandRef::new_zst(bx, elem); |
| } else { |
| return None; |
| } |
| } |
| _ => return None, |
| } |
| } |
| |
| Some(o) |
| } |
| LocalRef::PendingOperand => { |
| bug!("use of {:?} before def", place_ref); |
| } |
| LocalRef::Place(..) | LocalRef::UnsizedPlace(..) => { |
| // watch out for locals that do not have an |
| // alloca; they are handled somewhat differently |
| None |
| } |
| } |
| } |
| |
| pub fn codegen_consume( |
| &mut self, |
| bx: &mut Bx, |
| place_ref: mir::PlaceRef<'tcx>, |
| ) -> OperandRef<'tcx, Bx::Value> { |
| debug!("codegen_consume(place_ref={:?})", place_ref); |
| |
| let ty = self.monomorphized_place_ty(place_ref); |
| let layout = bx.cx().layout_of(ty); |
| |
| // ZSTs don't require any actual memory access. |
| if layout.is_zst() { |
| return OperandRef::new_zst(bx, layout); |
| } |
| |
| if let Some(o) = self.maybe_codegen_consume_direct(bx, place_ref) { |
| return o; |
| } |
| |
| // for most places, to consume them we just load them |
| // out from their home |
| let place = self.codegen_place(bx, place_ref); |
| bx.load_operand(place) |
| } |
| |
| pub fn codegen_operand( |
| &mut self, |
| bx: &mut Bx, |
| operand: &mir::Operand<'tcx>, |
| ) -> OperandRef<'tcx, Bx::Value> { |
| debug!("codegen_operand(operand={:?})", operand); |
| |
| match *operand { |
| mir::Operand::Copy(ref place) | mir::Operand::Move(ref place) => { |
| self.codegen_consume(bx, place.as_ref()) |
| } |
| |
| mir::Operand::Constant(ref constant) => { |
| // This cannot fail because we checked all required_consts in advance. |
| self.eval_mir_constant_to_operand(bx, constant).unwrap_or_else(|_err| { |
| span_bug!(constant.span, "erroneous constant not captured by required_consts") |
| }) |
| } |
| } |
| } |
| } |
