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rvalue.rs
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use std::macros::assert_matches;
use arrayvec::ArrayVec;
use rustc_abi::{self as abi, FIRST_VARIANT, FieldIdx};
use rustc_middle::ty::adjustment::PointerCoercion;
use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf, TyAndLayout};
use rustc_middle::ty::{self, Instance, Ty, TyCtxt};
use rustc_middle::{bug, mir, span_bug};
use rustc_session::config::OptLevel;
use rustc_span::{DUMMY_SP, Span};
use tracing::{debug, instrument, trace};
use super::operand::{OperandRef, OperandValue};
use super::place::PlaceRef;
use super::{FunctionCx, LocalRef};
use crate::common::IntPredicate;
use crate::traits::*;
use crate::{MemFlags, base};
impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
#[instrument(level = "trace", skip(self, bx))]
pub(crate) fn codegen_rvalue(
&mut self,
bx: &mut Bx,
dest: PlaceRef<'tcx, Bx::Value>,
rvalue: &mir::Rvalue<'tcx>,
) {
match *rvalue {
mir::Rvalue::Use(ref operand) => {
let cg_operand = self.codegen_operand(bx, operand);
// FIXME: consider not copying constants through stack. (Fixable by codegen'ing
// constants into `OperandValue::Ref`; why don’t we do that yet if we don’t?)
cg_operand.val.store(bx, dest);
}
mir::Rvalue::Cast(
mir::CastKind::PointerCoercion(PointerCoercion::Unsize, _),
ref source,
_,
) => {
// The destination necessarily contains a wide pointer, so if
// it's a scalar pair, it's a wide pointer or newtype thereof.
if bx.cx().is_backend_scalar_pair(dest.layout) {
// Into-coerce of a thin pointer to a wide pointer -- just
// use the operand path.
let temp = self.codegen_rvalue_operand(bx, rvalue);
temp.val.store(bx, dest);
return;
}
// Unsize of a nontrivial struct. I would prefer for
// this to be eliminated by MIR building, but
// `CoerceUnsized` can be passed by a where-clause,
// so the (generic) MIR may not be able to expand it.
let operand = self.codegen_operand(bx, source);
match operand.val {
OperandValue::Pair(..) | OperandValue::Immediate(_) => {
// Unsize from an immediate structure. We don't
// really need a temporary alloca here, but
// avoiding it would require us to have
// `coerce_unsized_into` use `extractvalue` to
// index into the struct, and this case isn't
// important enough for it.
debug!("codegen_rvalue: creating ugly alloca");
let scratch = PlaceRef::alloca(bx, operand.layout);
scratch.storage_live(bx);
operand.val.store(bx, scratch);
base::coerce_unsized_into(bx, scratch, dest);
scratch.storage_dead(bx);
}
OperandValue::Ref(val) => {
if val.llextra.is_some() {
bug!("unsized coercion on an unsized rvalue");
}
base::coerce_unsized_into(bx, val.with_type(operand.layout), dest);
}
OperandValue::ZeroSized => {
bug!("unsized coercion on a ZST rvalue");
}
}
}
mir::Rvalue::Cast(mir::CastKind::Transmute, ref operand, _ty) => {
let src = self.codegen_operand(bx, operand);
self.codegen_transmute(bx, src, dest);
}
mir::Rvalue::Repeat(ref elem, count) => {
let cg_elem = self.codegen_operand(bx, elem);
// Do not generate the loop for zero-sized elements or empty arrays.
if dest.layout.is_zst() {
return;
}
// If `v` is an integer constant whose value is just a single byte repeated N times,
// emit a `memset` filling the entire `dest` with that byte.
let try_init_all_same = |bx: &mut Bx, v| {
let start = dest.val.llval;
let size = bx.const_usize(dest.layout.size.bytes());
// Use llvm.memset.p0i8.* to initialize all same byte arrays
if let Some(int) = bx.cx().const_to_opt_u128(v, false) {
let bytes = &int.to_le_bytes()[..cg_elem.layout.size.bytes_usize()];
let first = bytes[0];
if bytes[1..].iter().all(|&b| b == first) {
let fill = bx.cx().const_u8(first);
bx.memset(start, fill, size, dest.val.align, MemFlags::empty());
return true;
}
}
// Use llvm.memset.p0i8.* to initialize byte arrays
let v = bx.from_immediate(v);
if bx.cx().val_ty(v) == bx.cx().type_i8() {
bx.memset(start, v, size, dest.val.align, MemFlags::empty());
return true;
}
false
};
trace!(?cg_elem.val);
match cg_elem.val {
OperandValue::Immediate(v) => {
if try_init_all_same(bx, v) {
return;
}
}
OperandValue::Pair(a, b) => {
let a_is_undef = bx.cx().is_undef(a);
match (a_is_undef, bx.cx().is_undef(b)) {
// Can happen for uninit unions
(true, true) => {
// FIXME: can we produce better output here?
}
(false, true) | (true, false) => {
let val = if a_is_undef { b } else { a };
if try_init_all_same(bx, val) {
return;
}
}
(false, false) => {
// FIXME: if both are the same value, use try_init_all_same
}
}
}
OperandValue::ZeroSized => unreachable!("checked above"),
OperandValue::Ref(..) => {}
}
let count = self
.monomorphize(count)
.try_to_target_usize(bx.tcx())
.expect("expected monomorphic const in codegen");
bx.write_operand_repeatedly(cg_elem, count, dest);
}
// This implementation does field projection, so never use it for `RawPtr`,
// which will always be fine with the `codegen_rvalue_operand` path below.
mir::Rvalue::Aggregate(ref kind, ref operands)
if !matches!(**kind, mir::AggregateKind::RawPtr(..)) =>
{
let (variant_index, variant_dest, active_field_index) = match **kind {
mir::AggregateKind::Adt(_, variant_index, _, _, active_field_index) => {
let variant_dest = dest.project_downcast(bx, variant_index);
(variant_index, variant_dest, active_field_index)
}
_ => (FIRST_VARIANT, dest, None),
};
if active_field_index.is_some() {
assert_eq!(operands.len(), 1);
}
for (i, operand) in operands.iter_enumerated() {
let op = self.codegen_operand(bx, operand);
// Do not generate stores and GEPis for zero-sized fields.
if !op.layout.is_zst() {
let field_index = active_field_index.unwrap_or(i);
let field = if let mir::AggregateKind::Array(_) = **kind {
let llindex = bx.cx().const_usize(field_index.as_u32().into());
variant_dest.project_index(bx, llindex)
} else {
variant_dest.project_field(bx, field_index.as_usize())
};
op.val.store(bx, field);
}
}
dest.codegen_set_discr(bx, variant_index);
}
_ => {
assert!(self.rvalue_creates_operand(rvalue, DUMMY_SP));
let temp = self.codegen_rvalue_operand(bx, rvalue);
temp.val.store(bx, dest);
}
}
}
fn codegen_transmute(
&mut self,
bx: &mut Bx,
src: OperandRef<'tcx, Bx::Value>,
dst: PlaceRef<'tcx, Bx::Value>,
) {
// The MIR validator enforces no unsized transmutes.
assert!(src.layout.is_sized());
assert!(dst.layout.is_sized());
if let Some(val) = self.codegen_transmute_operand(bx, src, dst.layout) {
val.store(bx, dst);
return;
}
match src.val {
OperandValue::Ref(..) | OperandValue::ZeroSized => {
span_bug!(
self.mir.span,
"Operand path should have handled transmute \
from {src:?} to place {dst:?}"
);
}
OperandValue::Immediate(..) | OperandValue::Pair(..) => {
// When we have immediate(s), the alignment of the source is irrelevant,
// so we can store them using the destination's alignment.
src.val.store(bx, dst.val.with_type(src.layout));
}
}
}
/// Attempts to transmute an `OperandValue` to another `OperandValue`.
///
/// Returns `None` for cases that can't work in that framework, such as for
/// `Immediate`->`Ref` that needs an `alloc` to get the location.
pub(crate) fn codegen_transmute_operand(
&mut self,
bx: &mut Bx,
operand: OperandRef<'tcx, Bx::Value>,
cast: TyAndLayout<'tcx>,
) -> Option<OperandValue<Bx::Value>> {
// Check for transmutes that are always UB.
if operand.layout.size != cast.size
|| operand.layout.is_uninhabited()
|| cast.is_uninhabited()
{
if !operand.layout.is_uninhabited() {
// Since this is known statically and the input could have existed
// without already having hit UB, might as well trap for it.
bx.abort();
}
// Because this transmute is UB, return something easy to generate,
// since it's fine that later uses of the value are probably UB.
return Some(OperandValue::poison(bx, cast));
}
let operand_kind = self.value_kind(operand.layout);
let cast_kind = self.value_kind(cast);
match operand.val {
OperandValue::Ref(source_place_val) => {
assert_eq!(source_place_val.llextra, None);
assert_matches!(operand_kind, OperandValueKind::Ref);
// The existing alignment is part of `source_place_val`,
// so that alignment will be used, not `cast`'s.
Some(bx.load_operand(source_place_val.with_type(cast)).val)
}
OperandValue::ZeroSized => {
let OperandValueKind::ZeroSized = operand_kind else {
bug!("Found {operand_kind:?} for operand {operand:?}");
};
if let OperandValueKind::ZeroSized = cast_kind {
Some(OperandValue::ZeroSized)
} else {
None
}
}
OperandValue::Immediate(imm) => {
let OperandValueKind::Immediate(from_scalar) = operand_kind else {
bug!("Found {operand_kind:?} for operand {operand:?}");
};
if let OperandValueKind::Immediate(to_scalar) = cast_kind
&& from_scalar.size(self.cx) == to_scalar.size(self.cx)
{
let from_backend_ty = bx.backend_type(operand.layout);
let to_backend_ty = bx.backend_type(cast);
Some(OperandValue::Immediate(self.transmute_immediate(
bx,
imm,
from_scalar,
from_backend_ty,
to_scalar,
to_backend_ty,
)))
} else {
None
}
}
OperandValue::Pair(imm_a, imm_b) => {
let OperandValueKind::Pair(in_a, in_b) = operand_kind else {
bug!("Found {operand_kind:?} for operand {operand:?}");
};
if let OperandValueKind::Pair(out_a, out_b) = cast_kind
&& in_a.size(self.cx) == out_a.size(self.cx)
&& in_b.size(self.cx) == out_b.size(self.cx)
{
let in_a_ibty = bx.scalar_pair_element_backend_type(operand.layout, 0, false);
let in_b_ibty = bx.scalar_pair_element_backend_type(operand.layout, 1, false);
let out_a_ibty = bx.scalar_pair_element_backend_type(cast, 0, false);
let out_b_ibty = bx.scalar_pair_element_backend_type(cast, 1, false);
Some(OperandValue::Pair(
self.transmute_immediate(bx, imm_a, in_a, in_a_ibty, out_a, out_a_ibty),
self.transmute_immediate(bx, imm_b, in_b, in_b_ibty, out_b, out_b_ibty),
))
} else {
None
}
}
}
}
/// Cast one of the immediates from an [`OperandValue::Immediate`]
/// or an [`OperandValue::Pair`] to an immediate of the target type.
///
/// Returns `None` if the cast is not possible.
fn cast_immediate(
&self,
bx: &mut Bx,
mut imm: Bx::Value,
from_scalar: abi::Scalar,
from_backend_ty: Bx::Type,
to_scalar: abi::Scalar,
to_backend_ty: Bx::Type,
) -> Option<Bx::Value> {
use abi::Primitive::*;
// When scalars are passed by value, there's no metadata recording their
// valid ranges. For example, `char`s are passed as just `i32`, with no
// way for LLVM to know that they're 0x10FFFF at most. Thus we assume
// the range of the input value too, not just the output range.
self.assume_scalar_range(bx, imm, from_scalar, from_backend_ty);
imm = match (from_scalar.primitive(), to_scalar.primitive()) {
(Int(_, is_signed), Int(..)) => bx.intcast(imm, to_backend_ty, is_signed),
(Float(_), Float(_)) => {
let srcsz = bx.cx().float_width(from_backend_ty);
let dstsz = bx.cx().float_width(to_backend_ty);
if dstsz > srcsz {
bx.fpext(imm, to_backend_ty)
} else if srcsz > dstsz {
bx.fptrunc(imm, to_backend_ty)
} else {
imm
}
}
(Int(_, is_signed), Float(_)) => {
if is_signed {
bx.sitofp(imm, to_backend_ty)
} else {
bx.uitofp(imm, to_backend_ty)
}
}
(Pointer(..), Pointer(..)) => bx.pointercast(imm, to_backend_ty),
(Int(_, is_signed), Pointer(..)) => {
let usize_imm = bx.intcast(imm, bx.cx().type_isize(), is_signed);
bx.inttoptr(usize_imm, to_backend_ty)
}
(Float(_), Int(_, is_signed)) => bx.cast_float_to_int(is_signed, imm, to_backend_ty),
_ => return None,
};
Some(imm)
}
/// Transmutes one of the immediates from an [`OperandValue::Immediate`]
/// or an [`OperandValue::Pair`] to an immediate of the target type.
///
/// `to_backend_ty` must be the *non*-immediate backend type (so it will be
/// `i8`, not `i1`, for `bool`-like types.)
fn transmute_immediate(
&self,
bx: &mut Bx,
mut imm: Bx::Value,
from_scalar: abi::Scalar,
from_backend_ty: Bx::Type,
to_scalar: abi::Scalar,
to_backend_ty: Bx::Type,
) -> Bx::Value {
assert_eq!(from_scalar.size(self.cx), to_scalar.size(self.cx));
use abi::Primitive::*;
imm = bx.from_immediate(imm);
// If we have a scalar, we must already know its range. Either
//
// 1) It's a parameter with `range` parameter metadata,
// 2) It's something we `load`ed with `!range` metadata, or
// 3) After a transmute we `assume`d the range (see below).
//
// That said, last time we tried removing this, it didn't actually help
// the rustc-perf results, so might as well keep doing it
// <https://github.com/rust-lang/rust/pull/135610#issuecomment-2599275182>
self.assume_scalar_range(bx, imm, from_scalar, from_backend_ty);
imm = match (from_scalar.primitive(), to_scalar.primitive()) {
(Int(..) | Float(_), Int(..) | Float(_)) => bx.bitcast(imm, to_backend_ty),
(Pointer(..), Pointer(..)) => bx.pointercast(imm, to_backend_ty),
(Int(..), Pointer(..)) => bx.ptradd(bx.const_null(bx.type_ptr()), imm),
(Pointer(..), Int(..)) => {
// FIXME: this exposes the provenance, which shouldn't be necessary.
bx.ptrtoint(imm, to_backend_ty)
}
(Float(_), Pointer(..)) => {
let int_imm = bx.bitcast(imm, bx.cx().type_isize());
bx.ptradd(bx.const_null(bx.type_ptr()), int_imm)
}
(Pointer(..), Float(_)) => {
// FIXME: this exposes the provenance, which shouldn't be necessary.
let int_imm = bx.ptrtoint(imm, bx.cx().type_isize());
bx.bitcast(int_imm, to_backend_ty)
}
};
// This `assume` remains important for cases like (a conceptual)
// transmute::<u32, NonZeroU32>(x) == 0
// since it's never passed to something with parameter metadata (especially
// after MIR inlining) so the only way to tell the backend about the
// constraint that the `transmute` introduced is to `assume` it.
self.assume_scalar_range(bx, imm, to_scalar, to_backend_ty);
imm = bx.to_immediate_scalar(imm, to_scalar);
imm
}
fn assume_scalar_range(
&self,
bx: &mut Bx,
imm: Bx::Value,
scalar: abi::Scalar,
backend_ty: Bx::Type,
) {
if matches!(self.cx.sess().opts.optimize, OptLevel::No) || scalar.is_always_valid(self.cx) {
return;
}
match scalar.primitive() {
abi::Primitive::Int(..) => {
let range = scalar.valid_range(self.cx);
bx.assume_integer_range(imm, backend_ty, range);
}
abi::Primitive::Pointer(abi::AddressSpace::DATA)
if !scalar.valid_range(self.cx).contains(0) =>
{
bx.assume_nonnull(imm);
}
abi::Primitive::Pointer(..) | abi::Primitive::Float(..) => {}
}
}
pub(crate) fn codegen_rvalue_unsized(
&mut self,
bx: &mut Bx,
indirect_dest: PlaceRef<'tcx, Bx::Value>,
rvalue: &mir::Rvalue<'tcx>,
) {
debug!(
"codegen_rvalue_unsized(indirect_dest.llval={:?}, rvalue={:?})",
indirect_dest.val.llval, rvalue
);
match *rvalue {
mir::Rvalue::Use(ref operand) => {
let cg_operand = self.codegen_operand(bx, operand);
cg_operand.val.store_unsized(bx, indirect_dest);
}
_ => bug!("unsized assignment other than `Rvalue::Use`"),
}
}
pub(crate) fn codegen_rvalue_operand(
&mut self,
bx: &mut Bx,
rvalue: &mir::Rvalue<'tcx>,
) -> OperandRef<'tcx, Bx::Value> {
assert!(
self.rvalue_creates_operand(rvalue, DUMMY_SP),
"cannot codegen {rvalue:?} to operand",
);
match *rvalue {
mir::Rvalue::Cast(ref kind, ref source, mir_cast_ty) => {
let operand = self.codegen_operand(bx, source);
debug!("cast operand is {:?}", operand);
let cast = bx.cx().layout_of(self.monomorphize(mir_cast_ty));
let val = match *kind {
mir::CastKind::PointerExposeProvenance => {
assert!(bx.cx().is_backend_immediate(cast));
let llptr = operand.immediate();
let llcast_ty = bx.cx().immediate_backend_type(cast);
let lladdr = bx.ptrtoint(llptr, llcast_ty);
OperandValue::Immediate(lladdr)
}
mir::CastKind::PointerCoercion(PointerCoercion::ReifyFnPointer, _) => {
match *operand.layout.ty.kind() {
ty::FnDef(def_id, args) => {
let instance = ty::Instance::resolve_for_fn_ptr(
bx.tcx(),
bx.typing_env(),
def_id,
args,
)
.unwrap();
OperandValue::Immediate(bx.get_fn_addr(instance))
}
_ => bug!("{} cannot be reified to a fn ptr", operand.layout.ty),
}
}
mir::CastKind::PointerCoercion(PointerCoercion::ClosureFnPointer(_), _) => {
match *operand.layout.ty.kind() {
ty::Closure(def_id, args) => {
let instance = Instance::resolve_closure(
bx.cx().tcx(),
def_id,
args,
ty::ClosureKind::FnOnce,
);
OperandValue::Immediate(bx.cx().get_fn_addr(instance))
}
_ => bug!("{} cannot be cast to a fn ptr", operand.layout.ty),
}
}
mir::CastKind::PointerCoercion(PointerCoercion::UnsafeFnPointer, _) => {
// This is a no-op at the LLVM level.
operand.val
}
mir::CastKind::PointerCoercion(PointerCoercion::Unsize, _) => {
assert!(bx.cx().is_backend_scalar_pair(cast));
let (lldata, llextra) = operand.val.pointer_parts();
let (lldata, llextra) =
base::unsize_ptr(bx, lldata, operand.layout.ty, cast.ty, llextra);
OperandValue::Pair(lldata, llextra)
}
mir::CastKind::PointerCoercion(
PointerCoercion::MutToConstPointer | PointerCoercion::ArrayToPointer, _
) => {
bug!("{kind:?} is for borrowck, and should never appear in codegen");
}
mir::CastKind::PtrToPtr
if bx.cx().is_backend_scalar_pair(operand.layout) =>
{
if let OperandValue::Pair(data_ptr, meta) = operand.val {
if bx.cx().is_backend_scalar_pair(cast) {
OperandValue::Pair(data_ptr, meta)
} else {
// Cast of wide-ptr to thin-ptr is an extraction of data-ptr.
OperandValue::Immediate(data_ptr)
}
} else {
bug!("unexpected non-pair operand");
}
}
mir::CastKind::PointerCoercion(PointerCoercion::DynStar, _) => {
let (lldata, llextra) = operand.val.pointer_parts();
let (lldata, llextra) =
base::cast_to_dyn_star(bx, lldata, operand.layout, cast.ty, llextra);
OperandValue::Pair(lldata, llextra)
}
| mir::CastKind::IntToInt
| mir::CastKind::FloatToInt
| mir::CastKind::FloatToFloat
| mir::CastKind::IntToFloat
| mir::CastKind::PtrToPtr
| mir::CastKind::FnPtrToPtr
// Since int2ptr can have arbitrary integer types as input (so we have to do
// sign extension and all that), it is currently best handled in the same code
// path as the other integer-to-X casts.
| mir::CastKind::PointerWithExposedProvenance => {
let imm = operand.immediate();
let operand_kind = self.value_kind(operand.layout);
let OperandValueKind::Immediate(from_scalar) = operand_kind else {
bug!("Found {operand_kind:?} for operand {operand:?}");
};
let from_backend_ty = bx.cx().immediate_backend_type(operand.layout);
assert!(bx.cx().is_backend_immediate(cast));
let to_backend_ty = bx.cx().immediate_backend_type(cast);
if operand.layout.is_uninhabited() {
let val = OperandValue::Immediate(bx.cx().const_poison(to_backend_ty));
return OperandRef { val, layout: cast };
}
let cast_kind = self.value_kind(cast);
let OperandValueKind::Immediate(to_scalar) = cast_kind else {
bug!("Found {cast_kind:?} for operand {cast:?}");
};
self.cast_immediate(bx, imm, from_scalar, from_backend_ty, to_scalar, to_backend_ty)
.map(OperandValue::Immediate)
.unwrap_or_else(|| {
bug!("Unsupported cast of {operand:?} to {cast:?}");
})
}
mir::CastKind::Transmute => {
self.codegen_transmute_operand(bx, operand, cast).unwrap_or_else(|| {
bug!("Unsupported transmute-as-operand of {operand:?} to {cast:?}");
})
}
};
OperandRef { val, layout: cast }
}
mir::Rvalue::Ref(_, bk, place) => {
let mk_ref = move |tcx: TyCtxt<'tcx>, ty: Ty<'tcx>| {
Ty::new_ref(tcx, tcx.lifetimes.re_erased, ty, bk.to_mutbl_lossy())
};
self.codegen_place_to_pointer(bx, place, mk_ref)
}
mir::Rvalue::CopyForDeref(place) => {
self.codegen_operand(bx, &mir::Operand::Copy(place))
}
mir::Rvalue::RawPtr(kind, place) => {
let mk_ptr = move |tcx: TyCtxt<'tcx>, ty: Ty<'tcx>| {
Ty::new_ptr(tcx, ty, kind.to_mutbl_lossy())
};
self.codegen_place_to_pointer(bx, place, mk_ptr)
}
mir::Rvalue::Len(place) => {
let size = self.evaluate_array_len(bx, place);
OperandRef {
val: OperandValue::Immediate(size),
layout: bx.cx().layout_of(bx.tcx().types.usize),
}
}
mir::Rvalue::BinaryOp(op_with_overflow, box (ref lhs, ref rhs))
if let Some(op) = op_with_overflow.overflowing_to_wrapping() =>
{
let lhs = self.codegen_operand(bx, lhs);
let rhs = self.codegen_operand(bx, rhs);
let result = self.codegen_scalar_checked_binop(
bx,
op,
lhs.immediate(),
rhs.immediate(),
lhs.layout.ty,
);
let val_ty = op.ty(bx.tcx(), lhs.layout.ty, rhs.layout.ty);
let operand_ty = Ty::new_tup(bx.tcx(), &[val_ty, bx.tcx().types.bool]);
OperandRef { val: result, layout: bx.cx().layout_of(operand_ty) }
}
mir::Rvalue::BinaryOp(op, box (ref lhs, ref rhs)) => {
let lhs = self.codegen_operand(bx, lhs);
let rhs = self.codegen_operand(bx, rhs);
let llresult = match (lhs.val, rhs.val) {
(
OperandValue::Pair(lhs_addr, lhs_extra),
OperandValue::Pair(rhs_addr, rhs_extra),
) => self.codegen_wide_ptr_binop(
bx,
op,
lhs_addr,
lhs_extra,
rhs_addr,
rhs_extra,
lhs.layout.ty,
),
(OperandValue::Immediate(lhs_val), OperandValue::Immediate(rhs_val)) => {
self.codegen_scalar_binop(bx, op, lhs_val, rhs_val, lhs.layout.ty)
}
_ => bug!(),
};
OperandRef {
val: OperandValue::Immediate(llresult),
layout: bx.cx().layout_of(op.ty(bx.tcx(), lhs.layout.ty, rhs.layout.ty)),
}
}
mir::Rvalue::UnaryOp(op, ref operand) => {
let operand = self.codegen_operand(bx, operand);
let is_float = operand.layout.ty.is_floating_point();
let (val, layout) = match op {
mir::UnOp::Not => {
let llval = bx.not(operand.immediate());
(OperandValue::Immediate(llval), operand.layout)
}
mir::UnOp::Neg => {
let llval = if is_float {
bx.fneg(operand.immediate())
} else {
bx.neg(operand.immediate())
};
(OperandValue::Immediate(llval), operand.layout)
}
mir::UnOp::PtrMetadata => {
assert!(operand.layout.ty.is_raw_ptr() || operand.layout.ty.is_ref(),);
let (_, meta) = operand.val.pointer_parts();
assert_eq!(operand.layout.fields.count() > 1, meta.is_some());
if let Some(meta) = meta {
(OperandValue::Immediate(meta), operand.layout.field(self.cx, 1))
} else {
(OperandValue::ZeroSized, bx.cx().layout_of(bx.tcx().types.unit))
}
}
};
assert!(
val.is_expected_variant_for_type(self.cx, layout),
"Made wrong variant {val:?} for type {layout:?}",
);
OperandRef { val, layout }
}
mir::Rvalue::Discriminant(ref place) => {
let discr_ty = rvalue.ty(self.mir, bx.tcx());
let discr_ty = self.monomorphize(discr_ty);
let discr = self.codegen_place(bx, place.as_ref()).codegen_get_discr(bx, discr_ty);
OperandRef {
val: OperandValue::Immediate(discr),
layout: self.cx.layout_of(discr_ty),
}
}
mir::Rvalue::NullaryOp(ref null_op, ty) => {
let ty = self.monomorphize(ty);
let layout = bx.cx().layout_of(ty);
let val = match null_op {
mir::NullOp::SizeOf => {
assert!(bx.cx().type_is_sized(ty));
let val = layout.size.bytes();
bx.cx().const_usize(val)
}
mir::NullOp::AlignOf => {
assert!(bx.cx().type_is_sized(ty));
let val = layout.align.abi.bytes();
bx.cx().const_usize(val)
}
mir::NullOp::OffsetOf(fields) => {
let val = bx
.tcx()
.offset_of_subfield(bx.typing_env(), layout, fields.iter())
.bytes();
bx.cx().const_usize(val)
}
mir::NullOp::UbChecks => {
let val = bx.tcx().sess.ub_checks();
bx.cx().const_bool(val)
}
mir::NullOp::ContractChecks => {
let val = bx.tcx().sess.contract_checks();
bx.cx().const_bool(val)
}
};
let tcx = self.cx.tcx();
OperandRef {
val: OperandValue::Immediate(val),
layout: self.cx.layout_of(tcx.types.usize),
}
}
mir::Rvalue::ThreadLocalRef(def_id) => {
assert!(bx.cx().tcx().is_static(def_id));
let layout = bx.layout_of(bx.cx().tcx().static_ptr_ty(def_id, bx.typing_env()));
let static_ = if !def_id.is_local() && bx.cx().tcx().needs_thread_local_shim(def_id)
{
let instance = ty::Instance {
def: ty::InstanceKind::ThreadLocalShim(def_id),
args: ty::GenericArgs::empty(),
};
let fn_ptr = bx.get_fn_addr(instance);
let fn_abi = bx.fn_abi_of_instance(instance, ty::List::empty());
let fn_ty = bx.fn_decl_backend_type(fn_abi);
let fn_attrs = if bx.tcx().def_kind(instance.def_id()).has_codegen_attrs() {
Some(bx.tcx().codegen_fn_attrs(instance.def_id()))
} else {
None
};
bx.call(fn_ty, fn_attrs, Some(fn_abi), fn_ptr, &[], None, Some(instance))
} else {
bx.get_static(def_id)
};
OperandRef { val: OperandValue::Immediate(static_), layout }
}
mir::Rvalue::Use(ref operand) => self.codegen_operand(bx, operand),
mir::Rvalue::Repeat(..) => bug!("{rvalue:?} in codegen_rvalue_operand"),
mir::Rvalue::Aggregate(_, ref fields) => {
let ty = rvalue.ty(self.mir, self.cx.tcx());
let ty = self.monomorphize(ty);
let layout = self.cx.layout_of(ty);
// `rvalue_creates_operand` has arranged that we only get here if
// we can build the aggregate immediate from the field immediates.
let mut inputs = ArrayVec::<Bx::Value, 2>::new();
let mut input_scalars = ArrayVec::<abi::Scalar, 2>::new();
for field_idx in layout.fields.index_by_increasing_offset() {
let field_idx = FieldIdx::from_usize(field_idx);
let op = self.codegen_operand(bx, &fields[field_idx]);
let values = op.val.immediates_or_place().left_or_else(|p| {
bug!("Field {field_idx:?} is {p:?} making {layout:?}");
});
let scalars = self.value_kind(op.layout).scalars().unwrap();
assert_eq!(values.len(), scalars.len());
inputs.extend(values);
input_scalars.extend(scalars);
}
let output_scalars = self.value_kind(layout).scalars().unwrap();
itertools::izip!(&mut inputs, input_scalars, output_scalars).for_each(
|(v, in_s, out_s)| {
if in_s != out_s {
// We have to be really careful about bool here, because
// `(bool,)` stays i1 but `Cell<bool>` becomes i8.
*v = bx.from_immediate(*v);
*v = bx.to_immediate_scalar(*v, out_s);
}
},
);
let val = OperandValue::from_immediates(inputs);
assert!(
val.is_expected_variant_for_type(self.cx, layout),
"Made wrong variant {val:?} for type {layout:?}",
);
OperandRef { val, layout }
}
mir::Rvalue::ShallowInitBox(ref operand, content_ty) => {
let operand = self.codegen_operand(bx, operand);
let val = operand.immediate();
let content_ty = self.monomorphize(content_ty);
let box_layout = bx.cx().layout_of(Ty::new_box(bx.tcx(), content_ty));
OperandRef { val: OperandValue::Immediate(val), layout: box_layout }
}
mir::Rvalue::WrapUnsafeBinder(ref operand, binder_ty) => {
let operand = self.codegen_operand(bx, operand);
let binder_ty = self.monomorphize(binder_ty);
let layout = bx.cx().layout_of(binder_ty);
OperandRef { val: operand.val, layout }
}
}
}
fn evaluate_array_len(&mut self, bx: &mut Bx, place: mir::Place<'tcx>) -> Bx::Value {
// ZST are passed as operands and require special handling
// because codegen_place() panics if Local is operand.
if let Some(index) = place.as_local() {
if let LocalRef::Operand(op) = self.locals[index] {
if let ty::Array(_, n) = op.layout.ty.kind() {
let n = n
.try_to_target_usize(bx.tcx())
.expect("expected monomorphic const in codegen");
return bx.cx().const_usize(n);
}
}
}
// use common size calculation for non zero-sized types
let cg_value = self.codegen_place(bx, place.as_ref());
cg_value.len(bx.cx())
}
/// Codegen an `Rvalue::RawPtr` or `Rvalue::Ref`
fn codegen_place_to_pointer(
&mut self,
bx: &mut Bx,
place: mir::Place<'tcx>,
mk_ptr_ty: impl FnOnce(TyCtxt<'tcx>, Ty<'tcx>) -> Ty<'tcx>,
) -> OperandRef<'tcx, Bx::Value> {
let cg_place = self.codegen_place(bx, place.as_ref());
let val = cg_place.val.address();
let ty = cg_place.layout.ty;
assert!(
if bx.cx().type_has_metadata(ty) {
matches!(val, OperandValue::Pair(..))
} else {
matches!(val, OperandValue::Immediate(..))
},
"Address of place was unexpectedly {val:?} for pointee type {ty:?}",
);
OperandRef { val, layout: self.cx.layout_of(mk_ptr_ty(self.cx.tcx(), ty)) }
}
fn codegen_scalar_binop(
&mut self,
bx: &mut Bx,
op: mir::BinOp,
lhs: Bx::Value,
rhs: Bx::Value,
input_ty: Ty<'tcx>,
) -> Bx::Value {
let is_float = input_ty.is_floating_point();
let is_signed = input_ty.is_signed();
match op {
mir::BinOp::Add => {
if is_float {
bx.fadd(lhs, rhs)
} else {
bx.add(lhs, rhs)
}
}
mir::BinOp::AddUnchecked => {
if is_signed {
bx.unchecked_sadd(lhs, rhs)
} else {
bx.unchecked_uadd(lhs, rhs)
}
}
mir::BinOp::Sub => {
if is_float {
bx.fsub(lhs, rhs)
} else {
bx.sub(lhs, rhs)
}
}
mir::BinOp::SubUnchecked => {
if is_signed {
bx.unchecked_ssub(lhs, rhs)
} else {
bx.unchecked_usub(lhs, rhs)
}
}
mir::BinOp::Mul => {
if is_float {
bx.fmul(lhs, rhs)
} else {
bx.mul(lhs, rhs)
}
}
mir::BinOp::MulUnchecked => {
if is_signed {
bx.unchecked_smul(lhs, rhs)
} else {
bx.unchecked_umul(lhs, rhs)
}
}
mir::BinOp::Div => {
if is_float {
bx.fdiv(lhs, rhs)
} else if is_signed {
bx.sdiv(lhs, rhs)
} else {
bx.udiv(lhs, rhs)
}
}
mir::BinOp::Rem => {
if is_float {
bx.frem(lhs, rhs)
} else if is_signed {
bx.srem(lhs, rhs)
} else {
bx.urem(lhs, rhs)
}
}
mir::BinOp::BitOr => bx.or(lhs, rhs),
mir::BinOp::BitAnd => bx.and(lhs, rhs),
mir::BinOp::BitXor => bx.xor(lhs, rhs),
mir::BinOp::Offset => {
let pointee_type = input_ty
.builtin_deref(true)
.unwrap_or_else(|| bug!("deref of non-pointer {:?}", input_ty));
let pointee_layout = bx.cx().layout_of(pointee_type);
if pointee_layout.is_zst() {
// `Offset` works in terms of the size of pointee,
// so offsetting a pointer to ZST is a noop.
lhs
} else {
let llty = bx.cx().backend_type(pointee_layout);
bx.inbounds_gep(llty, lhs, &[rhs])
}
}
mir::BinOp::Shl | mir::BinOp::ShlUnchecked => {
let rhs = base::build_shift_expr_rhs(bx, lhs, rhs, op == mir::BinOp::ShlUnchecked);
bx.shl(lhs, rhs)
}
mir::BinOp::Shr | mir::BinOp::ShrUnchecked => {
let rhs = base::build_shift_expr_rhs(bx, lhs, rhs, op == mir::BinOp::ShrUnchecked);
if is_signed { bx.ashr(lhs, rhs) } else { bx.lshr(lhs, rhs) }
}
mir::BinOp::Ne
| mir::BinOp::Lt
| mir::BinOp::Gt
| mir::BinOp::Eq
| mir::BinOp::Le
| mir::BinOp::Ge => {
if is_float {
bx.fcmp(base::bin_op_to_fcmp_predicate(op), lhs, rhs)
} else {
bx.icmp(base::bin_op_to_icmp_predicate(op, is_signed), lhs, rhs)
}
}
mir::BinOp::Cmp => {
use std::cmp::Ordering;
assert!(!is_float);
let pred = |op| base::bin_op_to_icmp_predicate(op, is_signed);
if bx.cx().tcx().sess.opts.optimize == OptLevel::No {
// FIXME: This actually generates tighter assembly, and is a classic trick
// <https://graphics.stanford.edu/~seander/bithacks.html#CopyIntegerSign>