use itertools::Itertools as _; use rustc_abi::{self as abi, BackendRepr, FIRST_VARIANT}; use rustc_middle::ty::adjustment::PointerCoercion; use rustc_middle::ty::layout::{HasTyCtxt, HasTypingEnv, LayoutOf, TyAndLayout}; use rustc_middle::ty::{self, Instance, Ty, TyCtxt}; use rustc_middle::{bug, mir, span_bug}; use rustc_session::config::OptLevel; use tracing::{debug, instrument}; use super::FunctionCx; use super::operand::{OperandRef, OperandRefBuilder, OperandValue}; use super::place::{PlaceRef, PlaceValue, codegen_tag_value}; use crate::common::{IntPredicate, TypeKind}; 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); // Crucially, we do *not* use `OperandValue::Ref` for types with // `BackendRepr::Scalar | BackendRepr::ScalarPair`. This ensures we match the MIR // semantics regarding when assignment operators allow overlap of LHS and RHS. if matches!( cg_operand.layout.backend_repr, BackendRepr::Scalar(..) | BackendRepr::ScalarPair(..), ) { debug_assert!(!matches!(cg_operand.val, OperandValue::Ref(..))); } // 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 | mir::CastKind::Subtype, ref operand, _ty, ) => { let src = self.codegen_operand(bx, operand); self.codegen_transmute(bx, src, dest); } mir::Rvalue::Repeat(ref elem, count) => { // Do not generate the loop for zero-sized elements or empty arrays. if dest.layout.is_zst() { return; } // When the element is a const with all bytes uninit, emit a single memset that // writes undef to the entire destination. if let mir::Operand::Constant(const_op) = elem { let val = self.eval_mir_constant(const_op); if val.all_bytes_uninit(self.cx.tcx()) { let size = bx.const_usize(dest.layout.size.bytes()); bx.memset( dest.val.llval, bx.const_undef(bx.type_i8()), size, dest.val.align, MemFlags::empty(), ); return; } } let cg_elem = self.codegen_operand(bx, elem); 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 Ok(&byte) = bytes.iter().all_equal_value() { let fill = bx.cx().const_u8(byte); 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 }; if let OperandValue::Immediate(v) = cg_elem.val && try_init_all_same(bx, v) { return; } 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); } _ => { let temp = self.codegen_rvalue_operand(bx, rvalue); temp.val.store(bx, dest); } } } /// Transmutes the `src` value to the destination type by writing it to `dst`. /// /// See also [`Self::codegen_transmute_operand`] for cases that can be done /// without needing a pre-allocated place for the destination. 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 src.layout.size != dst.layout.size || src.layout.is_uninhabited() || dst.layout.is_uninhabited() { // These cases are all UB to actually hit, so don't emit code for them. // (The size mismatches are reachable via `transmute_unchecked`.) bx.unreachable_nonterminator(); } else { // Since in this path we have a place anyway, we can store or copy to it, // making sure we use the destination place's alignment even if the // source would normally have a higher one. src.val.store(bx, dst.val.with_type(src.layout)); } } /// Transmutes an `OperandValue` to another `OperandValue`. /// /// This is supported for all cases where the `cast` type is SSA, /// but for non-ZSTs with [`abi::BackendRepr::Memory`] it ICEs. pub(crate) fn codegen_transmute_operand( &mut self, bx: &mut Bx, operand: OperandRef<'tcx, Bx::Value>, cast: TyAndLayout<'tcx>, ) -> OperandValue { if let abi::BackendRepr::Memory { .. } = cast.backend_repr && !cast.is_zst() { span_bug!(self.mir.span, "Use `codegen_transmute` to transmute to {cast:?}"); } // `Layout` is interned, so we can do a cheap check for things that are // exactly the same and thus don't need any handling. if abi::Layout::eq(&operand.layout.layout, &cast.layout) { return operand.val; } // Check for transmutes that are always UB. if operand.layout.size != cast.size || operand.layout.is_uninhabited() || cast.is_uninhabited() { bx.unreachable_nonterminator(); // We still need to return a value of the appropriate type, but // it's already UB so do the easiest thing available. return OperandValue::poison(bx, cast); } // To or from pointers takes different methods, so we use this to restrict // the SimdVector case to types which can be `bitcast` between each other. #[inline] fn vector_can_bitcast(x: abi::Scalar) -> bool { matches!( x, abi::Scalar::Initialized { value: abi::Primitive::Int(..) | abi::Primitive::Float(..), .. } ) } let cx = bx.cx(); match (operand.val, operand.layout.backend_repr, cast.backend_repr) { _ if cast.is_zst() => OperandValue::ZeroSized, (OperandValue::Ref(source_place_val), abi::BackendRepr::Memory { .. }, _) => { assert_eq!(source_place_val.llextra, None); // The existing alignment is part of `source_place_val`, // so that alignment will be used, not `cast`'s. bx.load_operand(source_place_val.with_type(cast)).val } ( OperandValue::Immediate(imm), abi::BackendRepr::Scalar(from_scalar), abi::BackendRepr::Scalar(to_scalar), ) if from_scalar.size(cx) == to_scalar.size(cx) => { OperandValue::Immediate(transmute_scalar(bx, imm, from_scalar, to_scalar)) } ( OperandValue::Immediate(imm), abi::BackendRepr::SimdVector { element: from_scalar, .. }, abi::BackendRepr::SimdVector { element: to_scalar, .. }, ) if vector_can_bitcast(from_scalar) && vector_can_bitcast(to_scalar) => { let to_backend_ty = bx.cx().immediate_backend_type(cast); OperandValue::Immediate(bx.bitcast(imm, to_backend_ty)) } ( OperandValue::Pair(imm_a, imm_b), abi::BackendRepr::ScalarPair(in_a, in_b), abi::BackendRepr::ScalarPair(out_a, out_b), ) if in_a.size(cx) == out_a.size(cx) && in_b.size(cx) == out_b.size(cx) => { OperandValue::Pair( transmute_scalar(bx, imm_a, in_a, out_a), transmute_scalar(bx, imm_b, in_b, out_b), ) } _ => { // For any other potentially-tricky cases, make a temporary instead. // If anything else wants the target local to be in memory this won't // be hit, as `codegen_transmute` will get called directly. Thus this // is only for places where everything else wants the operand form, // and thus it's not worth making those places get it from memory. // // Notably, Scalar ⇌ ScalarPair cases go here to avoid padding // and endianness issues, as do SimdVector ones to avoid worrying // about things like f32x8 ⇌ ptrx4 that would need multiple steps. let align = Ord::max(operand.layout.align.abi, cast.align.abi); let size = Ord::max(operand.layout.size, cast.size); let temp = PlaceValue::alloca(bx, size, align); bx.lifetime_start(temp.llval, size); operand.val.store(bx, temp.with_type(operand.layout)); let val = bx.load_operand(temp.with_type(cast)).val; bx.lifetime_end(temp.llval, size); val } } } /// 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 { 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. assume_scalar_range(bx, imm, from_scalar, from_backend_ty, None); 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) } pub(crate) fn codegen_rvalue_operand( &mut self, bx: &mut Bx, rvalue: &mir::Rvalue<'tcx>, ) -> OperandRef<'tcx, Bx::Value> { 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::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 abi::BackendRepr::Scalar(from_scalar) = operand.layout.backend_repr else { bug!("Found non-scalar 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 abi::BackendRepr::Scalar(to_scalar) = cast.layout.backend_repr else { bug!("Found non-scalar for cast {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 | mir::CastKind::Subtype => { self.codegen_transmute_operand(bx, operand, 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::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, rhs.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 operand = self.codegen_consume(bx, place.as_ref()); let discr = operand.codegen_get_discr(self, 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.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(null_op.ty(tcx)), } } 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_instance_attrs(instance.def)) } else { None }; bx.call( fn_ty, fn_attrs.as_deref(), 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(ref elem, len_const) => { // All arrays have `BackendRepr::Memory`, so only the ZST cases // end up here. Anything else forces the destination local to be // `Memory`, and thus ends up handled in `codegen_rvalue` instead. let operand = self.codegen_operand(bx, elem); let array_ty = Ty::new_array_with_const_len(bx.tcx(), operand.layout.ty, len_const); let array_ty = self.monomorphize(array_ty); let array_layout = bx.layout_of(array_ty); assert!(array_layout.is_zst()); OperandRef { val: OperandValue::ZeroSized, layout: array_layout } } mir::Rvalue::Aggregate(ref kind, ref fields) => { let (variant_index, active_field_index) = match **kind { mir::AggregateKind::Adt(_, variant_index, _, _, active_field_index) => { (variant_index, active_field_index) } _ => (FIRST_VARIANT, None), }; let ty = rvalue.ty(self.mir, self.cx.tcx()); let ty = self.monomorphize(ty); let layout = self.cx.layout_of(ty); let mut builder = OperandRefBuilder::new(layout); for (field_idx, field) in fields.iter_enumerated() { let op = self.codegen_operand(bx, field); let fi = active_field_index.unwrap_or(field_idx); builder.insert_field(bx, variant_index, fi, op); } let tag_result = codegen_tag_value(self.cx, variant_index, layout); match tag_result { Err(super::place::UninhabitedVariantError) => { // Like codegen_set_discr we use a sound abort, but could // potentially `unreachable` or just return the poison for // more optimizability, if that turns out to be helpful. bx.abort(); let val = OperandValue::poison(bx, layout); OperandRef { val, layout } } Ok(maybe_tag_value) => { if let Some((tag_field, tag_imm)) = maybe_tag_value { builder.insert_imm(tag_field, tag_imm); } builder.build(bx.cx()) } } } 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 } } } } /// 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().tcx().type_has_metadata(ty, bx.cx().typing_env()) { 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, lhs_ty: Ty<'tcx>, rhs_ty: Ty<'tcx>, ) -> Bx::Value { let is_float = lhs_ty.is_floating_point(); let is_signed = lhs_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 = lhs_ty .builtin_deref(true) .unwrap_or_else(|| bug!("deref of non-pointer {:?}", lhs_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); if !rhs_ty.is_signed() { bx.inbounds_nuw_gep(llty, lhs, &[rhs]) } else { 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 => { assert!(!is_float); bx.three_way_compare(lhs_ty, lhs, rhs) } mir::BinOp::AddWithOverflow | mir::BinOp::SubWithOverflow | mir::BinOp::MulWithOverflow => { bug!("{op:?} needs to return a pair, so call codegen_scalar_checked_binop instead") } } } fn codegen_wide_ptr_binop( &mut self, bx: &mut Bx, op: mir::BinOp, lhs_addr: Bx::Value, lhs_extra: Bx::Value, rhs_addr: Bx::Value, rhs_extra: Bx::Value, _input_ty: Ty<'tcx>, ) -> Bx::Value { match op { mir::BinOp::Eq => { let lhs = bx.icmp(IntPredicate::IntEQ, lhs_addr, rhs_addr); let rhs = bx.icmp(IntPredicate::IntEQ, lhs_extra, rhs_extra); bx.and(lhs, rhs) } mir::BinOp::Ne => { let lhs = bx.icmp(IntPredicate::IntNE, lhs_addr, rhs_addr); let rhs = bx.icmp(IntPredicate::IntNE, lhs_extra, rhs_extra); bx.or(lhs, rhs) } mir::BinOp::Le | mir::BinOp::Lt | mir::BinOp::Ge | mir::BinOp::Gt => { // a OP b ~ a.0 STRICT(OP) b.0 | (a.0 == b.0 && a.1 OP a.1) let (op, strict_op) = match op { mir::BinOp::Lt => (IntPredicate::IntULT, IntPredicate::IntULT), mir::BinOp::Le => (IntPredicate::IntULE, IntPredicate::IntULT), mir::BinOp::Gt => (IntPredicate::IntUGT, IntPredicate::IntUGT), mir::BinOp::Ge => (IntPredicate::IntUGE, IntPredicate::IntUGT), _ => bug!(), }; let lhs = bx.icmp(strict_op, lhs_addr, rhs_addr); let and_lhs = bx.icmp(IntPredicate::IntEQ, lhs_addr, rhs_addr); let and_rhs = bx.icmp(op, lhs_extra, rhs_extra); let rhs = bx.and(and_lhs, and_rhs); bx.or(lhs, rhs) } _ => { bug!("unexpected wide ptr binop"); } } } fn codegen_scalar_checked_binop( &mut self, bx: &mut Bx, op: mir::BinOp, lhs: Bx::Value, rhs: Bx::Value, input_ty: Ty<'tcx>, ) -> OperandValue { let (val, of) = match op { // These are checked using intrinsics mir::BinOp::Add | mir::BinOp::Sub | mir::BinOp::Mul => { let oop = match op { mir::BinOp::Add => OverflowOp::Add, mir::BinOp::Sub => OverflowOp::Sub, mir::BinOp::Mul => OverflowOp::Mul, _ => unreachable!(), }; bx.checked_binop(oop, input_ty, lhs, rhs) } _ => bug!("Operator `{:?}` is not a checkable operator", op), }; OperandValue::Pair(val, of) } } /// Transmutes a single scalar value `imm` from `from_scalar` to `to_scalar`. /// /// This is expected to be in *immediate* form, as seen in [`OperandValue::Immediate`] /// or [`OperandValue::Pair`] (so `i1` for bools, not `i8`, for example). /// /// ICEs if the passed-in `imm` is not a value of the expected type for /// `from_scalar`, such as if it's a vector or a pair. pub(super) fn transmute_scalar<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( bx: &mut Bx, mut imm: Bx::Value, from_scalar: abi::Scalar, to_scalar: abi::Scalar, ) -> Bx::Value { assert_eq!(from_scalar.size(bx.cx()), to_scalar.size(bx.cx())); let imm_ty = bx.cx().val_ty(imm); assert_ne!( bx.cx().type_kind(imm_ty), TypeKind::Vector, "Vector type {imm_ty:?} not allowed in transmute_scalar {from_scalar:?} -> {to_scalar:?}" ); // While optimizations will remove no-op transmutes, they might still be // there in debug or things that aren't no-op in MIR because they change // the Rust type but not the underlying layout/niche. if from_scalar == to_scalar { return imm; } use abi::Primitive::*; imm = bx.from_immediate(imm); let from_backend_ty = bx.cx().type_from_scalar(from_scalar); debug_assert_eq!(bx.cx().val_ty(imm), from_backend_ty); let to_backend_ty = bx.cx().type_from_scalar(to_scalar); // 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 // assume_scalar_range(bx, imm, from_scalar, from_backend_ty, Some(&to_scalar)); 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) } }; debug_assert_eq!(bx.cx().val_ty(imm), to_backend_ty); // This `assume` remains important for cases like (a conceptual) // transmute::(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. assume_scalar_range(bx, imm, to_scalar, to_backend_ty, Some(&from_scalar)); imm = bx.to_immediate_scalar(imm, to_scalar); imm } /// Emits an `assume` call that `imm`'s value is within the known range of `scalar`. /// /// If `known` is `Some`, only emits the assume if it's more specific than /// whatever is already known from the range of *that* scalar. fn assume_scalar_range<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( bx: &mut Bx, imm: Bx::Value, scalar: abi::Scalar, backend_ty: Bx::Type, known: Option<&abi::Scalar>, ) { if matches!(bx.cx().sess().opts.optimize, OptLevel::No) { return; } match (scalar, known) { (abi::Scalar::Union { .. }, _) => return, (_, None) => { if scalar.is_always_valid(bx.cx()) { return; } } (abi::Scalar::Initialized { valid_range, .. }, Some(known)) => { let known_range = known.valid_range(bx.cx()); if valid_range.contains_range(known_range, scalar.size(bx.cx())) { return; } } } match scalar.primitive() { abi::Primitive::Int(..) => { let range = scalar.valid_range(bx.cx()); bx.assume_integer_range(imm, backend_ty, range); } abi::Primitive::Pointer(abi::AddressSpace::ZERO) if !scalar.valid_range(bx.cx()).contains(0) => { bx.assume_nonnull(imm); } abi::Primitive::Pointer(..) | abi::Primitive::Float(..) => {} } }