7086dd83cc
The initial naming of "Abi" was an awful mistake, conveying wrong ideas about how psABIs worked and even more about what the enum meant. It was only meant to represent the way the value would be described to a codegen backend as it was lowered to that intermediate representation. It was never meant to mean anything about the actual psABI handling! The conflation is because LLVM typically will associate a certain form with a certain ABI, but even that does not hold when the special cases that actually exist arise, plus the IR annotations that modify the ABI. Reframe `rustc_abi::Abi` as the `BackendRepr` of the type, and rename `BackendRepr::Aggregate` as `BackendRepr::Memory`. Unfortunately, due to the persistent misunderstandings, this too is now incorrect: - Scattered ABI-relevant code is entangled with BackendRepr - We do not always pre-compute a correct BackendRepr that reflects how we "actually" want this value to be handled, so we leave the backend interface to also inject various special-cases here - In some cases `BackendRepr::Memory` is a "real" aggregate, but in others it is in fact using memory, and in some cases it is a scalar! Our rustc-to-backend lowering code handles this sort of thing right now. That will eventually be addressed by lifting duplicated lowering code to either rustc_codegen_ssa or rustc_target as appropriate.
663 lines
27 KiB
Rust
663 lines
27 KiB
Rust
use std::assert_matches::assert_matches;
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use std::fmt;
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use arrayvec::ArrayVec;
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use either::Either;
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use rustc_abi as abi;
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use rustc_abi::{Align, BackendRepr, Size};
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use rustc_middle::bug;
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use rustc_middle::mir::interpret::{Pointer, Scalar, alloc_range};
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use rustc_middle::mir::{self, ConstValue};
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use rustc_middle::ty::Ty;
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use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
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use tracing::debug;
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use super::place::{PlaceRef, PlaceValue};
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use super::{FunctionCx, LocalRef};
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use crate::traits::*;
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use crate::{MemFlags, size_of_val};
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/// The representation of a Rust value. The enum variant is in fact
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/// uniquely determined by the value's type, but is kept as a
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/// safety check.
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#[derive(Copy, Clone, Debug)]
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pub enum OperandValue<V> {
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/// A reference to the actual operand. The data is guaranteed
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/// to be valid for the operand's lifetime.
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/// The second value, if any, is the extra data (vtable or length)
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/// which indicates that it refers to an unsized rvalue.
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///
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/// An `OperandValue` *must* be this variant for any type for which
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/// [`LayoutTypeCodegenMethods::is_backend_ref`] returns `true`.
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/// (That basically amounts to "isn't one of the other variants".)
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///
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/// This holds a [`PlaceValue`] (like a [`PlaceRef`] does) with a pointer
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/// to the location holding the value. The type behind that pointer is the
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/// one returned by [`LayoutTypeCodegenMethods::backend_type`].
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Ref(PlaceValue<V>),
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/// A single LLVM immediate value.
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///
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/// An `OperandValue` *must* be this variant for any type for which
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/// [`LayoutTypeCodegenMethods::is_backend_immediate`] returns `true`.
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/// The backend value in this variant must be the *immediate* backend type,
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/// as returned by [`LayoutTypeCodegenMethods::immediate_backend_type`].
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Immediate(V),
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/// A pair of immediate LLVM values. Used by wide pointers too.
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///
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/// An `OperandValue` *must* be this variant for any type for which
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/// [`LayoutTypeCodegenMethods::is_backend_scalar_pair`] returns `true`.
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/// The backend values in this variant must be the *immediate* backend types,
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/// as returned by [`LayoutTypeCodegenMethods::scalar_pair_element_backend_type`]
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/// with `immediate: true`.
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Pair(V, V),
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/// A value taking no bytes, and which therefore needs no LLVM value at all.
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///
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/// If you ever need a `V` to pass to something, get a fresh poison value
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/// from [`ConstCodegenMethods::const_poison`].
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///
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/// An `OperandValue` *must* be this variant for any type for which
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/// `is_zst` on its `Layout` returns `true`. Note however that
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/// these values can still require alignment.
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ZeroSized,
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}
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impl<V: CodegenObject> OperandValue<V> {
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/// If this is ZeroSized/Immediate/Pair, return an array of the 0/1/2 values.
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/// If this is Ref, return the place.
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#[inline]
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pub(crate) fn immediates_or_place(self) -> Either<ArrayVec<V, 2>, PlaceValue<V>> {
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match self {
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OperandValue::ZeroSized => Either::Left(ArrayVec::new()),
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OperandValue::Immediate(a) => Either::Left(ArrayVec::from_iter([a])),
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OperandValue::Pair(a, b) => Either::Left([a, b].into()),
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OperandValue::Ref(p) => Either::Right(p),
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}
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}
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/// Given an array of 0/1/2 immediate values, return ZeroSized/Immediate/Pair.
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#[inline]
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pub(crate) fn from_immediates(immediates: ArrayVec<V, 2>) -> Self {
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let mut it = immediates.into_iter();
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let Some(a) = it.next() else {
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return OperandValue::ZeroSized;
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};
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let Some(b) = it.next() else {
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return OperandValue::Immediate(a);
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};
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OperandValue::Pair(a, b)
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}
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/// Treat this value as a pointer and return the data pointer and
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/// optional metadata as backend values.
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///
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/// If you're making a place, use [`Self::deref`] instead.
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pub(crate) fn pointer_parts(self) -> (V, Option<V>) {
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match self {
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OperandValue::Immediate(llptr) => (llptr, None),
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OperandValue::Pair(llptr, llextra) => (llptr, Some(llextra)),
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_ => bug!("OperandValue cannot be a pointer: {self:?}"),
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}
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}
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/// Treat this value as a pointer and return the place to which it points.
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///
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/// The pointer immediate doesn't inherently know its alignment,
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/// so you need to pass it in. If you want to get it from a type's ABI
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/// alignment, then maybe you want [`OperandRef::deref`] instead.
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///
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/// This is the inverse of [`PlaceValue::address`].
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pub(crate) fn deref(self, align: Align) -> PlaceValue<V> {
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let (llval, llextra) = self.pointer_parts();
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PlaceValue { llval, llextra, align }
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}
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pub(crate) fn is_expected_variant_for_type<'tcx, Cx: LayoutTypeCodegenMethods<'tcx>>(
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&self,
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cx: &Cx,
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ty: TyAndLayout<'tcx>,
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) -> bool {
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match self {
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OperandValue::ZeroSized => ty.is_zst(),
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OperandValue::Immediate(_) => cx.is_backend_immediate(ty),
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OperandValue::Pair(_, _) => cx.is_backend_scalar_pair(ty),
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OperandValue::Ref(_) => cx.is_backend_ref(ty),
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}
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}
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}
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/// An `OperandRef` is an "SSA" reference to a Rust value, along with
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/// its type.
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///
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/// NOTE: unless you know a value's type exactly, you should not
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/// generate LLVM opcodes acting on it and instead act via methods,
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/// to avoid nasty edge cases. In particular, using `Builder::store`
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/// directly is sure to cause problems -- use `OperandRef::store`
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/// instead.
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#[derive(Copy, Clone)]
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pub struct OperandRef<'tcx, V> {
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/// The value.
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pub val: OperandValue<V>,
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/// The layout of value, based on its Rust type.
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pub layout: TyAndLayout<'tcx>,
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}
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impl<V: CodegenObject> fmt::Debug for OperandRef<'_, V> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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write!(f, "OperandRef({:?} @ {:?})", self.val, self.layout)
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}
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}
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impl<'a, 'tcx, V: CodegenObject> OperandRef<'tcx, V> {
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pub fn zero_sized(layout: TyAndLayout<'tcx>) -> OperandRef<'tcx, V> {
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assert!(layout.is_zst());
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OperandRef { val: OperandValue::ZeroSized, layout }
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}
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pub(crate) fn from_const<Bx: BuilderMethods<'a, 'tcx, Value = V>>(
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bx: &mut Bx,
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val: mir::ConstValue<'tcx>,
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ty: Ty<'tcx>,
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) -> Self {
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let layout = bx.layout_of(ty);
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let val = match val {
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ConstValue::Scalar(x) => {
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let BackendRepr::Scalar(scalar) = layout.backend_repr else {
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bug!("from_const: invalid ByVal layout: {:#?}", layout);
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};
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let llval = bx.scalar_to_backend(x, scalar, bx.immediate_backend_type(layout));
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OperandValue::Immediate(llval)
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}
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ConstValue::ZeroSized => return OperandRef::zero_sized(layout),
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ConstValue::Slice { data, meta } => {
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let BackendRepr::ScalarPair(a_scalar, _) = layout.backend_repr else {
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bug!("from_const: invalid ScalarPair layout: {:#?}", layout);
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};
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let a = Scalar::from_pointer(
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Pointer::new(bx.tcx().reserve_and_set_memory_alloc(data).into(), Size::ZERO),
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&bx.tcx(),
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);
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let a_llval = bx.scalar_to_backend(
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a,
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a_scalar,
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bx.scalar_pair_element_backend_type(layout, 0, true),
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);
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let b_llval = bx.const_usize(meta);
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OperandValue::Pair(a_llval, b_llval)
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}
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ConstValue::Indirect { alloc_id, offset } => {
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let alloc = bx.tcx().global_alloc(alloc_id).unwrap_memory();
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return Self::from_const_alloc(bx, layout, alloc, offset);
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}
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};
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OperandRef { val, layout }
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}
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fn from_const_alloc<Bx: BuilderMethods<'a, 'tcx, Value = V>>(
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bx: &mut Bx,
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layout: TyAndLayout<'tcx>,
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alloc: rustc_middle::mir::interpret::ConstAllocation<'tcx>,
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offset: Size,
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) -> Self {
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let alloc_align = alloc.inner().align;
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assert!(alloc_align >= layout.align.abi);
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let read_scalar = |start, size, s: abi::Scalar, ty| {
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match alloc.0.read_scalar(
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bx,
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alloc_range(start, size),
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/*read_provenance*/ matches!(s.primitive(), abi::Primitive::Pointer(_)),
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) {
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Ok(val) => bx.scalar_to_backend(val, s, ty),
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Err(_) => bx.const_poison(ty),
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}
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};
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// It may seem like all types with `Scalar` or `ScalarPair` ABI are fair game at this point.
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// However, `MaybeUninit<u64>` is considered a `Scalar` as far as its layout is concerned --
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// and yet cannot be represented by an interpreter `Scalar`, since we have to handle the
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// case where some of the bytes are initialized and others are not. So, we need an extra
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// check that walks over the type of `mplace` to make sure it is truly correct to treat this
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// like a `Scalar` (or `ScalarPair`).
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match layout.backend_repr {
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BackendRepr::Scalar(s @ abi::Scalar::Initialized { .. }) => {
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let size = s.size(bx);
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assert_eq!(size, layout.size, "abi::Scalar size does not match layout size");
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let val = read_scalar(offset, size, s, bx.immediate_backend_type(layout));
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OperandRef { val: OperandValue::Immediate(val), layout }
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}
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BackendRepr::ScalarPair(
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a @ abi::Scalar::Initialized { .. },
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b @ abi::Scalar::Initialized { .. },
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) => {
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let (a_size, b_size) = (a.size(bx), b.size(bx));
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let b_offset = (offset + a_size).align_to(b.align(bx).abi);
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assert!(b_offset.bytes() > 0);
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let a_val = read_scalar(
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offset,
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a_size,
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a,
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bx.scalar_pair_element_backend_type(layout, 0, true),
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);
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let b_val = read_scalar(
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b_offset,
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b_size,
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b,
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bx.scalar_pair_element_backend_type(layout, 1, true),
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);
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OperandRef { val: OperandValue::Pair(a_val, b_val), layout }
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}
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_ if layout.is_zst() => OperandRef::zero_sized(layout),
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_ => {
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// Neither a scalar nor scalar pair. Load from a place
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// FIXME: should we cache `const_data_from_alloc` to avoid repeating this for the
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// same `ConstAllocation`?
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let init = bx.const_data_from_alloc(alloc);
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let base_addr = bx.static_addr_of(init, alloc_align, None);
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let llval = bx.const_ptr_byte_offset(base_addr, offset);
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bx.load_operand(PlaceRef::new_sized(llval, layout))
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}
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}
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}
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/// Asserts that this operand refers to a scalar and returns
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/// a reference to its value.
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pub fn immediate(self) -> V {
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match self.val {
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OperandValue::Immediate(s) => s,
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_ => bug!("not immediate: {:?}", self),
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}
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}
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/// Asserts that this operand is a pointer (or reference) and returns
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/// the place to which it points. (This requires no code to be emitted
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/// as we represent places using the pointer to the place.)
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///
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/// This uses [`Ty::builtin_deref`] to include the type of the place and
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/// assumes the place is aligned to the pointee's usual ABI alignment.
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///
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/// If you don't need the type, see [`OperandValue::pointer_parts`]
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/// or [`OperandValue::deref`].
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pub fn deref<Cx: CodegenMethods<'tcx>>(self, cx: &Cx) -> PlaceRef<'tcx, V> {
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if self.layout.ty.is_box() {
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// Derefer should have removed all Box derefs
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bug!("dereferencing {:?} in codegen", self.layout.ty);
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}
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let projected_ty = self
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.layout
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.ty
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.builtin_deref(true)
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.unwrap_or_else(|| bug!("deref of non-pointer {:?}", self));
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let layout = cx.layout_of(projected_ty);
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self.val.deref(layout.align.abi).with_type(layout)
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}
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/// If this operand is a `Pair`, we return an aggregate with the two values.
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/// For other cases, see `immediate`.
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pub fn immediate_or_packed_pair<Bx: BuilderMethods<'a, 'tcx, Value = V>>(
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self,
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bx: &mut Bx,
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) -> V {
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if let OperandValue::Pair(a, b) = self.val {
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let llty = bx.cx().immediate_backend_type(self.layout);
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debug!("Operand::immediate_or_packed_pair: packing {:?} into {:?}", self, llty);
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// Reconstruct the immediate aggregate.
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let mut llpair = bx.cx().const_poison(llty);
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llpair = bx.insert_value(llpair, a, 0);
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llpair = bx.insert_value(llpair, b, 1);
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llpair
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} else {
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self.immediate()
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}
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}
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/// If the type is a pair, we return a `Pair`, otherwise, an `Immediate`.
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pub fn from_immediate_or_packed_pair<Bx: BuilderMethods<'a, 'tcx, Value = V>>(
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bx: &mut Bx,
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llval: V,
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layout: TyAndLayout<'tcx>,
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) -> Self {
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let val = if let BackendRepr::ScalarPair(..) = layout.backend_repr {
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debug!("Operand::from_immediate_or_packed_pair: unpacking {:?} @ {:?}", llval, layout);
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// Deconstruct the immediate aggregate.
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let a_llval = bx.extract_value(llval, 0);
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let b_llval = bx.extract_value(llval, 1);
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OperandValue::Pair(a_llval, b_llval)
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} else {
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OperandValue::Immediate(llval)
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};
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OperandRef { val, layout }
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}
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pub(crate) fn extract_field<Bx: BuilderMethods<'a, 'tcx, Value = V>>(
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&self,
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bx: &mut Bx,
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i: usize,
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) -> Self {
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let field = self.layout.field(bx.cx(), i);
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let offset = self.layout.fields.offset(i);
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let mut val = match (self.val, self.layout.backend_repr) {
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// If the field is ZST, it has no data.
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_ if field.is_zst() => OperandValue::ZeroSized,
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// Newtype of a scalar, scalar pair or vector.
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(OperandValue::Immediate(_) | OperandValue::Pair(..), _)
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if field.size == self.layout.size =>
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{
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assert_eq!(offset.bytes(), 0);
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self.val
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}
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// Extract a scalar component from a pair.
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(OperandValue::Pair(a_llval, b_llval), BackendRepr::ScalarPair(a, b)) => {
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if offset.bytes() == 0 {
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assert_eq!(field.size, a.size(bx.cx()));
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OperandValue::Immediate(a_llval)
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} else {
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assert_eq!(offset, a.size(bx.cx()).align_to(b.align(bx.cx()).abi));
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assert_eq!(field.size, b.size(bx.cx()));
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OperandValue::Immediate(b_llval)
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}
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}
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// `#[repr(simd)]` types are also immediate.
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(OperandValue::Immediate(llval), BackendRepr::Vector { .. }) => {
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OperandValue::Immediate(bx.extract_element(llval, bx.cx().const_usize(i as u64)))
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}
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_ => bug!("OperandRef::extract_field({:?}): not applicable", self),
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};
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match (&mut val, field.backend_repr) {
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(OperandValue::ZeroSized, _) => {}
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(
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OperandValue::Immediate(llval),
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BackendRepr::Scalar(_) | BackendRepr::ScalarPair(..) | BackendRepr::Vector { .. },
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) => {
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// Bools in union fields needs to be truncated.
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*llval = bx.to_immediate(*llval, field);
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}
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(OperandValue::Pair(a, b), BackendRepr::ScalarPair(a_abi, b_abi)) => {
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// Bools in union fields needs to be truncated.
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*a = bx.to_immediate_scalar(*a, a_abi);
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*b = bx.to_immediate_scalar(*b, b_abi);
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}
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// Newtype vector of array, e.g. #[repr(simd)] struct S([i32; 4]);
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(OperandValue::Immediate(llval), BackendRepr::Memory { sized: true }) => {
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assert_matches!(self.layout.backend_repr, BackendRepr::Vector { .. });
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let llfield_ty = bx.cx().backend_type(field);
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// Can't bitcast an aggregate, so round trip through memory.
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let llptr = bx.alloca(field.size, field.align.abi);
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bx.store(*llval, llptr, field.align.abi);
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*llval = bx.load(llfield_ty, llptr, field.align.abi);
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}
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(
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OperandValue::Immediate(_),
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BackendRepr::Uninhabited | BackendRepr::Memory { sized: false },
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) => {
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bug!()
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}
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(OperandValue::Pair(..), _) => bug!(),
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(OperandValue::Ref(..), _) => bug!(),
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}
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OperandRef { val, layout: field }
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}
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}
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impl<'a, 'tcx, V: CodegenObject> OperandValue<V> {
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/// Returns an `OperandValue` that's generally UB to use in any way.
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|
///
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|
/// Depending on the `layout`, returns `ZeroSized` for ZSTs, an `Immediate` or
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/// `Pair` containing poison value(s), or a `Ref` containing a poison pointer.
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///
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/// Supports sized types only.
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|
pub fn poison<Bx: BuilderMethods<'a, 'tcx, Value = V>>(
|
|
bx: &mut Bx,
|
|
layout: TyAndLayout<'tcx>,
|
|
) -> OperandValue<V> {
|
|
assert!(layout.is_sized());
|
|
if layout.is_zst() {
|
|
OperandValue::ZeroSized
|
|
} else 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 ptr = bx.cx().type_ptr();
|
|
OperandValue::Ref(PlaceValue::new_sized(bx.const_poison(ptr), 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);
|
|
}
|
|
|
|
pub(crate) 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);
|
|
match self {
|
|
OperandValue::ZeroSized => {
|
|
// Avoid generating stores of zero-sized values, because the only way to have a
|
|
// zero-sized value is through `undef`/`poison`, and the store itself is useless.
|
|
}
|
|
OperandValue::Ref(val) => {
|
|
assert!(dest.layout.is_sized(), "cannot directly store unsized values");
|
|
if val.llextra.is_some() {
|
|
bug!("cannot directly store unsized values");
|
|
}
|
|
bx.typed_place_copy_with_flags(dest.val, val, dest.layout, flags);
|
|
}
|
|
OperandValue::Immediate(s) => {
|
|
let val = bx.from_immediate(s);
|
|
bx.store_with_flags(val, dest.val.llval, dest.val.align, flags);
|
|
}
|
|
OperandValue::Pair(a, b) => {
|
|
let BackendRepr::ScalarPair(a_scalar, b_scalar) = dest.layout.backend_repr else {
|
|
bug!("store_with_flags: invalid ScalarPair layout: {:#?}", dest.layout);
|
|
};
|
|
let b_offset = a_scalar.size(bx).align_to(b_scalar.align(bx).abi);
|
|
|
|
let val = bx.from_immediate(a);
|
|
let align = dest.val.align;
|
|
bx.store_with_flags(val, dest.val.llval, align, flags);
|
|
|
|
let llptr = bx.inbounds_ptradd(dest.val.llval, bx.const_usize(b_offset.bytes()));
|
|
let val = bx.from_immediate(b);
|
|
let align = dest.val.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));
|
|
|
|
let OperandValue::Ref(PlaceValue { llval: llptr, llextra: Some(llextra), .. }) = self
|
|
else {
|
|
bug!("store_unsized called with a sized value (or with an extern type)")
|
|
};
|
|
|
|
// 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) = size_of_val::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.dynamic_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_ptradd(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, _) => {
|
|
assert!(
|
|
!o.layout.ty.is_any_ptr(),
|
|
"Bad PlaceRef: destructing pointers should use cast/PtrMetadata, \
|
|
but tried to access field {f:?} of pointer {o:?}",
|
|
);
|
|
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::zero_sized(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::zero_sized(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) => {
|
|
let constant_ty = self.monomorphize(constant.ty());
|
|
// Most SIMD vector constants should be passed as immediates.
|
|
// (In particular, some intrinsics really rely on this.)
|
|
if constant_ty.is_simd() {
|
|
// However, some SIMD types do not actually use the vector ABI
|
|
// (in particular, packed SIMD types do not). Ensure we exclude those.
|
|
let layout = bx.layout_of(constant_ty);
|
|
if let BackendRepr::Vector { .. } = layout.backend_repr {
|
|
let (llval, ty) = self.immediate_const_vector(bx, constant);
|
|
return OperandRef {
|
|
val: OperandValue::Immediate(llval),
|
|
layout: bx.layout_of(ty),
|
|
};
|
|
}
|
|
}
|
|
self.eval_mir_constant_to_operand(bx, constant)
|
|
}
|
|
}
|
|
}
|
|
}
|