use std::assert_matches::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. fn codegen_transmute_operand( &mut self, bx: &mut Bx, operand: OperandRef<'tcx, Bx::Value>, cast: TyAndLayout<'tcx>, ) -> Option> { // 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); 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 { 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 // 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::(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) // For now, the critical niches are all over `Int`eger values. // Should floating-point values or pointers ever get more complex // niches, then this code will probably want to handle them too. || !matches!(scalar.primitive(), abi::Primitive::Int(..)) || scalar.is_always_valid(self.cx) { return; } let range = scalar.valid_range(self.cx); bx.assume_integer_range(imm, backend_ty, range); } 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::::new(); let mut input_scalars = ArrayVec::::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` 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 // // However, as of 2023-11 it optimizes worse in things like derived // `PartialOrd`, so only use it in debug for now. Once LLVM can handle it // better (see ), it'll // be worth trying it in optimized builds as well. let is_gt = bx.icmp(pred(mir::BinOp::Gt), lhs, rhs); let gtext = bx.zext(is_gt, bx.type_i8()); let is_lt = bx.icmp(pred(mir::BinOp::Lt), lhs, rhs); let ltext = bx.zext(is_lt, bx.type_i8()); bx.unchecked_ssub(gtext, ltext) } else { // These operations are those expected by `tests/codegen/integer-cmp.rs`, // from . let is_lt = bx.icmp(pred(mir::BinOp::Lt), lhs, rhs); let is_ne = bx.icmp(pred(mir::BinOp::Ne), lhs, rhs); let ge = bx.select( is_ne, bx.cx().const_i8(Ordering::Greater as i8), bx.cx().const_i8(Ordering::Equal as i8), ); bx.select(is_lt, bx.cx().const_i8(Ordering::Less as i8), ge) } } 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) } pub(crate) fn rvalue_creates_operand(&self, rvalue: &mir::Rvalue<'tcx>, span: Span) -> bool { match *rvalue { mir::Rvalue::Cast(mir::CastKind::Transmute, ref operand, cast_ty) => { let operand_ty = operand.ty(self.mir, self.cx.tcx()); let cast_layout = self.cx.layout_of(self.monomorphize(cast_ty)); let operand_layout = self.cx.layout_of(self.monomorphize(operand_ty)); match (self.value_kind(operand_layout), self.value_kind(cast_layout)) { // Can always load from a pointer as needed (OperandValueKind::Ref, _) => true, // ZST-to-ZST is the easiest thing ever (OperandValueKind::ZeroSized, OperandValueKind::ZeroSized) => true, // But if only one of them is a ZST the sizes can't match (OperandValueKind::ZeroSized, _) | (_, OperandValueKind::ZeroSized) => false, // Need to generate an `alloc` to get a pointer from an immediate (OperandValueKind::Immediate(..) | OperandValueKind::Pair(..), OperandValueKind::Ref) => false, // When we have scalar immediates, we can only convert things // where the sizes match, to avoid endianness questions. (OperandValueKind::Immediate(a), OperandValueKind::Immediate(b)) => a.size(self.cx) == b.size(self.cx), (OperandValueKind::Pair(a0, a1), OperandValueKind::Pair(b0, b1)) => a0.size(self.cx) == b0.size(self.cx) && a1.size(self.cx) == b1.size(self.cx), // Send mixings between scalars and pairs through the memory route // FIXME: Maybe this could use insertvalue/extractvalue instead? (OperandValueKind::Immediate(..), OperandValueKind::Pair(..)) | (OperandValueKind::Pair(..), OperandValueKind::Immediate(..)) => false, } } mir::Rvalue::Ref(..) | mir::Rvalue::CopyForDeref(..) | mir::Rvalue::RawPtr(..) | mir::Rvalue::Len(..) | mir::Rvalue::Cast(..) | // (*) mir::Rvalue::ShallowInitBox(..) | // (*) mir::Rvalue::BinaryOp(..) | mir::Rvalue::UnaryOp(..) | mir::Rvalue::Discriminant(..) | mir::Rvalue::NullaryOp(..) | mir::Rvalue::ThreadLocalRef(_) | mir::Rvalue::Use(..) | mir::Rvalue::WrapUnsafeBinder(..) => // (*) true, // Arrays are always aggregates, so it's not worth checking anything here. // (If it's really `[(); N]` or `[T; 0]` and we use the place path, fine.) mir::Rvalue::Repeat(..) => false, mir::Rvalue::Aggregate(ref kind, _) => { let allowed_kind = match **kind { // This always produces a `ty::RawPtr`, so will be Immediate or Pair mir::AggregateKind::RawPtr(..) => true, mir::AggregateKind::Array(..) => false, mir::AggregateKind::Tuple => true, mir::AggregateKind::Adt(def_id, ..) => { let adt_def = self.cx.tcx().adt_def(def_id); adt_def.is_struct() && !adt_def.repr().simd() } mir::AggregateKind::Closure(..) => true, // FIXME: Can we do this for simple coroutines too? mir::AggregateKind::Coroutine(..) | mir::AggregateKind::CoroutineClosure(..) => false, }; allowed_kind && { let ty = rvalue.ty(self.mir, self.cx.tcx()); let ty = self.monomorphize(ty); let layout = self.cx.spanned_layout_of(ty, span); !self.cx.is_backend_ref(layout) } } } // (*) this is only true if the type is suitable } /// Gets which variant of [`OperandValue`] is expected for a particular type. fn value_kind(&self, layout: TyAndLayout<'tcx>) -> OperandValueKind { if layout.is_zst() { OperandValueKind::ZeroSized } else if self.cx.is_backend_immediate(layout) { assert!(!self.cx.is_backend_scalar_pair(layout)); OperandValueKind::Immediate(match layout.backend_repr { abi::BackendRepr::Scalar(s) => s, abi::BackendRepr::Vector { element, .. } => element, x => span_bug!(self.mir.span, "Couldn't translate {x:?} as backend immediate"), }) } else if self.cx.is_backend_scalar_pair(layout) { let abi::BackendRepr::ScalarPair(s1, s2) = layout.backend_repr else { span_bug!( self.mir.span, "Couldn't translate {:?} as backend scalar pair", layout.backend_repr, ); }; OperandValueKind::Pair(s1, s2) } else { OperandValueKind::Ref } } } /// The variants of this match [`OperandValue`], giving details about the /// backend values that will be held in that other type. #[derive(Debug, Copy, Clone)] enum OperandValueKind { Ref, Immediate(abi::Scalar), Pair(abi::Scalar, abi::Scalar), ZeroSized, } impl OperandValueKind { fn scalars(self) -> Option> { Some(match self { OperandValueKind::ZeroSized => ArrayVec::new(), OperandValueKind::Immediate(a) => ArrayVec::from_iter([a]), OperandValueKind::Pair(a, b) => [a, b].into(), OperandValueKind::Ref => return None, }) } }