| use super::operand::{OperandRef, OperandValue}; |
| use super::place::PlaceRef; |
| use super::{FunctionCx, LocalRef}; |
| |
| use crate::base; |
| use crate::common::{self, IntPredicate, RealPredicate}; |
| use crate::traits::*; |
| use crate::MemFlags; |
| |
| use rustc_apfloat::{ieee, Float, Round, Status}; |
| use rustc_hir::lang_items::LangItem; |
| use rustc_middle::mir; |
| use rustc_middle::ty::cast::{CastTy, IntTy}; |
| use rustc_middle::ty::layout::HasTyCtxt; |
| use rustc_middle::ty::{self, adjustment::PointerCast, Instance, Ty, TyCtxt}; |
| use rustc_span::source_map::{Span, DUMMY_SP}; |
| use rustc_span::symbol::sym; |
| use rustc_target::abi::{Abi, Int, LayoutOf, Variants}; |
| |
| impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { |
| pub fn codegen_rvalue( |
| &mut self, |
| mut bx: Bx, |
| dest: PlaceRef<'tcx, Bx::Value>, |
| rvalue: &mir::Rvalue<'tcx>, |
| ) -> Bx { |
| debug!("codegen_rvalue(dest.llval={:?}, rvalue={:?})", dest.llval, rvalue); |
| |
| match *rvalue { |
| mir::Rvalue::Use(ref operand) => { |
| let cg_operand = self.codegen_operand(&mut 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(&mut bx, dest); |
| bx |
| } |
| |
| mir::Rvalue::Cast(mir::CastKind::Pointer(PointerCast::Unsize), ref source, _) => { |
| // The destination necessarily contains a fat pointer, so if |
| // it's a scalar pair, it's a fat pointer or newtype thereof. |
| if bx.cx().is_backend_scalar_pair(dest.layout) { |
| // Into-coerce of a thin pointer to a fat pointer -- just |
| // use the operand path. |
| let (mut bx, temp) = self.codegen_rvalue_operand(bx, rvalue); |
| temp.val.store(&mut bx, dest); |
| return bx; |
| } |
| |
| // 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(&mut 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(&mut bx, operand.layout); |
| scratch.storage_live(&mut bx); |
| operand.val.store(&mut bx, scratch); |
| base::coerce_unsized_into(&mut bx, scratch, dest); |
| scratch.storage_dead(&mut bx); |
| } |
| OperandValue::Ref(llref, None, align) => { |
| let source = PlaceRef::new_sized_aligned(llref, operand.layout, align); |
| base::coerce_unsized_into(&mut bx, source, dest); |
| } |
| OperandValue::Ref(_, Some(_), _) => { |
| bug!("unsized coercion on an unsized rvalue"); |
| } |
| } |
| bx |
| } |
| |
| mir::Rvalue::Repeat(ref elem, count) => { |
| let cg_elem = self.codegen_operand(&mut bx, elem); |
| |
| // Do not generate the loop for zero-sized elements or empty arrays. |
| if dest.layout.is_zst() { |
| return bx; |
| } |
| |
| if let OperandValue::Immediate(v) = cg_elem.val { |
| let zero = bx.const_usize(0); |
| let start = dest.project_index(&mut bx, zero).llval; |
| let size = bx.const_usize(dest.layout.size.bytes()); |
| |
| // Use llvm.memset.p0i8.* to initialize all zero arrays |
| if bx.cx().const_to_opt_uint(v) == Some(0) { |
| let fill = bx.cx().const_u8(0); |
| bx.memset(start, fill, size, dest.align, MemFlags::empty()); |
| return bx; |
| } |
| |
| // 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.align, MemFlags::empty()); |
| return bx; |
| } |
| } |
| |
| let count = |
| self.monomorphize(count).eval_usize(bx.cx().tcx(), ty::ParamEnv::reveal_all()); |
| |
| bx.write_operand_repeatedly(cg_elem, count, dest) |
| } |
| |
| mir::Rvalue::Aggregate(ref kind, ref operands) => { |
| let (dest, active_field_index) = match **kind { |
| mir::AggregateKind::Adt(adt_def, variant_index, _, _, active_field_index) => { |
| dest.codegen_set_discr(&mut bx, variant_index); |
| if adt_def.is_enum() { |
| (dest.project_downcast(&mut bx, variant_index), active_field_index) |
| } else { |
| (dest, active_field_index) |
| } |
| } |
| _ => (dest, None), |
| }; |
| for (i, operand) in operands.iter().enumerate() { |
| let op = self.codegen_operand(&mut 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 = dest.project_field(&mut bx, field_index); |
| op.val.store(&mut bx, field); |
| } |
| } |
| bx |
| } |
| |
| _ => { |
| assert!(self.rvalue_creates_operand(rvalue, DUMMY_SP)); |
| let (mut bx, temp) = self.codegen_rvalue_operand(bx, rvalue); |
| temp.val.store(&mut bx, dest); |
| bx |
| } |
| } |
| } |
| |
| pub fn codegen_rvalue_unsized( |
| &mut self, |
| mut bx: Bx, |
| indirect_dest: PlaceRef<'tcx, Bx::Value>, |
| rvalue: &mir::Rvalue<'tcx>, |
| ) -> Bx { |
| debug!( |
| "codegen_rvalue_unsized(indirect_dest.llval={:?}, rvalue={:?})", |
| indirect_dest.llval, rvalue |
| ); |
| |
| match *rvalue { |
| mir::Rvalue::Use(ref operand) => { |
| let cg_operand = self.codegen_operand(&mut bx, operand); |
| cg_operand.val.store_unsized(&mut bx, indirect_dest); |
| bx |
| } |
| |
| _ => bug!("unsized assignment other than `Rvalue::Use`"), |
| } |
| } |
| |
| pub fn codegen_rvalue_operand( |
| &mut self, |
| mut bx: Bx, |
| rvalue: &mir::Rvalue<'tcx>, |
| ) -> (Bx, OperandRef<'tcx, Bx::Value>) { |
| assert!( |
| self.rvalue_creates_operand(rvalue, DUMMY_SP), |
| "cannot codegen {:?} to operand", |
| rvalue, |
| ); |
| |
| match *rvalue { |
| mir::Rvalue::Cast(ref kind, ref source, mir_cast_ty) => { |
| let operand = self.codegen_operand(&mut bx, source); |
| debug!("cast operand is {:?}", operand); |
| let cast = bx.cx().layout_of(self.monomorphize(mir_cast_ty)); |
| |
| let val = match *kind { |
| mir::CastKind::Pointer(PointerCast::ReifyFnPointer) => { |
| match *operand.layout.ty.kind() { |
| ty::FnDef(def_id, substs) => { |
| if bx.cx().tcx().has_attr(def_id, sym::rustc_args_required_const) { |
| bug!("reifying a fn ptr that requires const arguments"); |
| } |
| let instance = ty::Instance::resolve_for_fn_ptr( |
| bx.tcx(), |
| ty::ParamEnv::reveal_all(), |
| def_id, |
| substs, |
| ) |
| .unwrap() |
| .polymorphize(bx.cx().tcx()); |
| OperandValue::Immediate(bx.get_fn_addr(instance)) |
| } |
| _ => bug!("{} cannot be reified to a fn ptr", operand.layout.ty), |
| } |
| } |
| mir::CastKind::Pointer(PointerCast::ClosureFnPointer(_)) => { |
| match *operand.layout.ty.kind() { |
| ty::Closure(def_id, substs) => { |
| let instance = Instance::resolve_closure( |
| bx.cx().tcx(), |
| def_id, |
| substs, |
| ty::ClosureKind::FnOnce, |
| ) |
| .polymorphize(bx.cx().tcx()); |
| OperandValue::Immediate(bx.cx().get_fn_addr(instance)) |
| } |
| _ => bug!("{} cannot be cast to a fn ptr", operand.layout.ty), |
| } |
| } |
| mir::CastKind::Pointer(PointerCast::UnsafeFnPointer) => { |
| // This is a no-op at the LLVM level. |
| operand.val |
| } |
| mir::CastKind::Pointer(PointerCast::Unsize) => { |
| assert!(bx.cx().is_backend_scalar_pair(cast)); |
| match operand.val { |
| OperandValue::Pair(lldata, llextra) => { |
| // unsize from a fat pointer -- this is a |
| // "trait-object-to-supertrait" coercion, for |
| // example, `&'a fmt::Debug + Send => &'a fmt::Debug`. |
| |
| // HACK(eddyb) have to bitcast pointers |
| // until LLVM removes pointee types. |
| let lldata = bx.pointercast( |
| lldata, |
| bx.cx().scalar_pair_element_backend_type(cast, 0, true), |
| ); |
| OperandValue::Pair(lldata, llextra) |
| } |
| OperandValue::Immediate(lldata) => { |
| // "standard" unsize |
| let (lldata, llextra) = base::unsize_thin_ptr( |
| &mut bx, |
| lldata, |
| operand.layout.ty, |
| cast.ty, |
| ); |
| OperandValue::Pair(lldata, llextra) |
| } |
| OperandValue::Ref(..) => { |
| bug!("by-ref operand {:?} in `codegen_rvalue_operand`", operand); |
| } |
| } |
| } |
| mir::CastKind::Pointer(PointerCast::MutToConstPointer) |
| | mir::CastKind::Misc |
| 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) { |
| let data_cast = bx.pointercast( |
| data_ptr, |
| bx.cx().scalar_pair_element_backend_type(cast, 0, true), |
| ); |
| OperandValue::Pair(data_cast, meta) |
| } else { |
| // cast to thin-ptr |
| // Cast of fat-ptr to thin-ptr is an extraction of data-ptr and |
| // pointer-cast of that pointer to desired pointer type. |
| let llcast_ty = bx.cx().immediate_backend_type(cast); |
| let llval = bx.pointercast(data_ptr, llcast_ty); |
| OperandValue::Immediate(llval) |
| } |
| } else { |
| bug!("unexpected non-pair operand"); |
| } |
| } |
| mir::CastKind::Pointer( |
| PointerCast::MutToConstPointer | PointerCast::ArrayToPointer, |
| ) |
| | mir::CastKind::Misc => { |
| assert!(bx.cx().is_backend_immediate(cast)); |
| let ll_t_out = bx.cx().immediate_backend_type(cast); |
| if operand.layout.abi.is_uninhabited() { |
| let val = OperandValue::Immediate(bx.cx().const_undef(ll_t_out)); |
| return (bx, OperandRef { val, layout: cast }); |
| } |
| let r_t_in = |
| CastTy::from_ty(operand.layout.ty).expect("bad input type for cast"); |
| let r_t_out = CastTy::from_ty(cast.ty).expect("bad output type for cast"); |
| let ll_t_in = bx.cx().immediate_backend_type(operand.layout); |
| match operand.layout.variants { |
| Variants::Single { index } => { |
| if let Some(discr) = |
| operand.layout.ty.discriminant_for_variant(bx.tcx(), index) |
| { |
| let discr_layout = bx.cx().layout_of(discr.ty); |
| let discr_t = bx.cx().immediate_backend_type(discr_layout); |
| let discr_val = bx.cx().const_uint_big(discr_t, discr.val); |
| let discr_val = |
| bx.intcast(discr_val, ll_t_out, discr.ty.is_signed()); |
| |
| return ( |
| bx, |
| OperandRef { |
| val: OperandValue::Immediate(discr_val), |
| layout: cast, |
| }, |
| ); |
| } |
| } |
| Variants::Multiple { .. } => {} |
| } |
| let llval = operand.immediate(); |
| |
| let mut signed = false; |
| if let Abi::Scalar(ref scalar) = operand.layout.abi { |
| if let Int(_, s) = scalar.value { |
| // We use `i1` for bytes that are always `0` or `1`, |
| // e.g., `#[repr(i8)] enum E { A, B }`, but we can't |
| // let LLVM interpret the `i1` as signed, because |
| // then `i1 1` (i.e., E::B) is effectively `i8 -1`. |
| signed = !scalar.is_bool() && s; |
| |
| let er = scalar.valid_range_exclusive(bx.cx()); |
| if er.end != er.start |
| && scalar.valid_range.end() >= scalar.valid_range.start() |
| { |
| // We want `table[e as usize ± k]` to not |
| // have bound checks, and this is the most |
| // convenient place to put the `assume`s. |
| if *scalar.valid_range.start() > 0 { |
| let enum_value_lower_bound = bx |
| .cx() |
| .const_uint_big(ll_t_in, *scalar.valid_range.start()); |
| let cmp_start = bx.icmp( |
| IntPredicate::IntUGE, |
| llval, |
| enum_value_lower_bound, |
| ); |
| bx.assume(cmp_start); |
| } |
| |
| let enum_value_upper_bound = |
| bx.cx().const_uint_big(ll_t_in, *scalar.valid_range.end()); |
| let cmp_end = bx.icmp( |
| IntPredicate::IntULE, |
| llval, |
| enum_value_upper_bound, |
| ); |
| bx.assume(cmp_end); |
| } |
| } |
| } |
| |
| let newval = match (r_t_in, r_t_out) { |
| (CastTy::Int(_), CastTy::Int(_)) => bx.intcast(llval, ll_t_out, signed), |
| (CastTy::Float, CastTy::Float) => { |
| let srcsz = bx.cx().float_width(ll_t_in); |
| let dstsz = bx.cx().float_width(ll_t_out); |
| if dstsz > srcsz { |
| bx.fpext(llval, ll_t_out) |
| } else if srcsz > dstsz { |
| bx.fptrunc(llval, ll_t_out) |
| } else { |
| llval |
| } |
| } |
| (CastTy::Int(_), CastTy::Float) => { |
| if signed { |
| bx.sitofp(llval, ll_t_out) |
| } else { |
| bx.uitofp(llval, ll_t_out) |
| } |
| } |
| (CastTy::Ptr(_) | CastTy::FnPtr, CastTy::Ptr(_)) => { |
| bx.pointercast(llval, ll_t_out) |
| } |
| (CastTy::Ptr(_) | CastTy::FnPtr, CastTy::Int(_)) => { |
| bx.ptrtoint(llval, ll_t_out) |
| } |
| (CastTy::Int(_), CastTy::Ptr(_)) => { |
| let usize_llval = bx.intcast(llval, bx.cx().type_isize(), signed); |
| bx.inttoptr(usize_llval, ll_t_out) |
| } |
| (CastTy::Float, CastTy::Int(IntTy::I)) => { |
| cast_float_to_int(&mut bx, true, llval, ll_t_in, ll_t_out) |
| } |
| (CastTy::Float, CastTy::Int(_)) => { |
| cast_float_to_int(&mut bx, false, llval, ll_t_in, ll_t_out) |
| } |
| _ => bug!("unsupported cast: {:?} to {:?}", operand.layout.ty, cast.ty), |
| }; |
| OperandValue::Immediate(newval) |
| } |
| }; |
| (bx, OperandRef { val, layout: cast }) |
| } |
| |
| mir::Rvalue::Ref(_, bk, place) => { |
| let mk_ref = move |tcx: TyCtxt<'tcx>, ty: Ty<'tcx>| { |
| tcx.mk_ref( |
| tcx.lifetimes.re_erased, |
| ty::TypeAndMut { ty, mutbl: bk.to_mutbl_lossy() }, |
| ) |
| }; |
| self.codegen_place_to_pointer(bx, place, mk_ref) |
| } |
| |
| mir::Rvalue::AddressOf(mutability, place) => { |
| let mk_ptr = move |tcx: TyCtxt<'tcx>, ty: Ty<'tcx>| { |
| tcx.mk_ptr(ty::TypeAndMut { ty, mutbl: mutability }) |
| }; |
| self.codegen_place_to_pointer(bx, place, mk_ptr) |
| } |
| |
| mir::Rvalue::Len(place) => { |
| let size = self.evaluate_array_len(&mut bx, place); |
| let operand = OperandRef { |
| val: OperandValue::Immediate(size), |
| layout: bx.cx().layout_of(bx.tcx().types.usize), |
| }; |
| (bx, operand) |
| } |
| |
| mir::Rvalue::BinaryOp(op, box (ref lhs, ref rhs)) => { |
| let lhs = self.codegen_operand(&mut bx, lhs); |
| let rhs = self.codegen_operand(&mut bx, rhs); |
| let llresult = match (lhs.val, rhs.val) { |
| ( |
| OperandValue::Pair(lhs_addr, lhs_extra), |
| OperandValue::Pair(rhs_addr, rhs_extra), |
| ) => self.codegen_fat_ptr_binop( |
| &mut 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(&mut bx, op, lhs_val, rhs_val, lhs.layout.ty) |
| } |
| |
| _ => bug!(), |
| }; |
| let operand = OperandRef { |
| val: OperandValue::Immediate(llresult), |
| layout: bx.cx().layout_of(op.ty(bx.tcx(), lhs.layout.ty, rhs.layout.ty)), |
| }; |
| (bx, operand) |
| } |
| mir::Rvalue::CheckedBinaryOp(op, box (ref lhs, ref rhs)) => { |
| let lhs = self.codegen_operand(&mut bx, lhs); |
| let rhs = self.codegen_operand(&mut bx, rhs); |
| let result = self.codegen_scalar_checked_binop( |
| &mut 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 = bx.tcx().intern_tup(&[val_ty, bx.tcx().types.bool]); |
| let operand = OperandRef { val: result, layout: bx.cx().layout_of(operand_ty) }; |
| |
| (bx, operand) |
| } |
| |
| mir::Rvalue::UnaryOp(op, ref operand) => { |
| let operand = self.codegen_operand(&mut bx, operand); |
| let lloperand = operand.immediate(); |
| let is_float = operand.layout.ty.is_floating_point(); |
| let llval = match op { |
| mir::UnOp::Not => bx.not(lloperand), |
| mir::UnOp::Neg => { |
| if is_float { |
| bx.fneg(lloperand) |
| } else { |
| bx.neg(lloperand) |
| } |
| } |
| }; |
| (bx, OperandRef { val: OperandValue::Immediate(llval), layout: operand.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(&mut bx, place.as_ref()) |
| .codegen_get_discr(&mut bx, discr_ty); |
| ( |
| bx, |
| OperandRef { |
| val: OperandValue::Immediate(discr), |
| layout: self.cx.layout_of(discr_ty), |
| }, |
| ) |
| } |
| |
| mir::Rvalue::NullaryOp(mir::NullOp::SizeOf, ty) => { |
| let ty = self.monomorphize(ty); |
| assert!(bx.cx().type_is_sized(ty)); |
| let val = bx.cx().const_usize(bx.cx().layout_of(ty).size.bytes()); |
| let tcx = self.cx.tcx(); |
| ( |
| bx, |
| OperandRef { |
| val: OperandValue::Immediate(val), |
| layout: self.cx.layout_of(tcx.types.usize), |
| }, |
| ) |
| } |
| |
| mir::Rvalue::NullaryOp(mir::NullOp::Box, content_ty) => { |
| let content_ty = self.monomorphize(content_ty); |
| let content_layout = bx.cx().layout_of(content_ty); |
| let llsize = bx.cx().const_usize(content_layout.size.bytes()); |
| let llalign = bx.cx().const_usize(content_layout.align.abi.bytes()); |
| let box_layout = bx.cx().layout_of(bx.tcx().mk_box(content_ty)); |
| let llty_ptr = bx.cx().backend_type(box_layout); |
| |
| // Allocate space: |
| let def_id = match bx.tcx().lang_items().require(LangItem::ExchangeMalloc) { |
| Ok(id) => id, |
| Err(s) => { |
| bx.cx().sess().fatal(&format!("allocation of `{}` {}", box_layout.ty, s)); |
| } |
| }; |
| let instance = ty::Instance::mono(bx.tcx(), def_id); |
| let r = bx.cx().get_fn_addr(instance); |
| let call = bx.call(r, &[llsize, llalign], None); |
| let val = bx.pointercast(call, llty_ptr); |
| |
| let operand = OperandRef { val: OperandValue::Immediate(val), layout: box_layout }; |
| (bx, operand) |
| } |
| mir::Rvalue::ThreadLocalRef(def_id) => { |
| assert!(bx.cx().tcx().is_static(def_id)); |
| let static_ = bx.get_static(def_id); |
| let layout = bx.layout_of(bx.cx().tcx().static_ptr_ty(def_id)); |
| let operand = OperandRef::from_immediate_or_packed_pair(&mut bx, static_, layout); |
| (bx, operand) |
| } |
| mir::Rvalue::Use(ref operand) => { |
| let operand = self.codegen_operand(&mut bx, operand); |
| (bx, operand) |
| } |
| mir::Rvalue::Repeat(..) | mir::Rvalue::Aggregate(..) => { |
| // According to `rvalue_creates_operand`, only ZST |
| // aggregate rvalues are allowed to be operands. |
| let ty = rvalue.ty(self.mir, self.cx.tcx()); |
| let operand = |
| OperandRef::new_zst(&mut bx, self.cx.layout_of(self.monomorphize(ty))); |
| (bx, operand) |
| } |
| } |
| } |
| |
| 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(Some(op)) = self.locals[index] { |
| if let ty::Array(_, n) = op.layout.ty.kind() { |
| let n = n.eval_usize(bx.cx().tcx(), ty::ParamEnv::reveal_all()); |
| 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::AddressOf` or `Rvalue::Ref` |
| fn codegen_place_to_pointer( |
| &mut self, |
| mut bx: Bx, |
| place: mir::Place<'tcx>, |
| mk_ptr_ty: impl FnOnce(TyCtxt<'tcx>, Ty<'tcx>) -> Ty<'tcx>, |
| ) -> (Bx, OperandRef<'tcx, Bx::Value>) { |
| let cg_place = self.codegen_place(&mut bx, place.as_ref()); |
| |
| let ty = cg_place.layout.ty; |
| |
| // Note: places are indirect, so storing the `llval` into the |
| // destination effectively creates a reference. |
| let val = if !bx.cx().type_has_metadata(ty) { |
| OperandValue::Immediate(cg_place.llval) |
| } else { |
| OperandValue::Pair(cg_place.llval, cg_place.llextra.unwrap()) |
| }; |
| (bx, OperandRef { val, layout: self.cx.layout_of(mk_ptr_ty(self.cx.tcx(), ty)) }) |
| } |
| |
| pub 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::Sub => { |
| if is_float { |
| bx.fsub(lhs, rhs) |
| } else { |
| bx.sub(lhs, rhs) |
| } |
| } |
| mir::BinOp::Mul => { |
| if is_float { |
| bx.fmul(lhs, rhs) |
| } else { |
| bx.mul(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 => bx.inbounds_gep(lhs, &[rhs]), |
| mir::BinOp::Shl => common::build_unchecked_lshift(bx, lhs, rhs), |
| mir::BinOp::Shr => common::build_unchecked_rshift(bx, input_ty, 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.to_hir_binop()), lhs, rhs) |
| } else { |
| bx.icmp(base::bin_op_to_icmp_predicate(op.to_hir_binop(), is_signed), lhs, rhs) |
| } |
| } |
| } |
| } |
| |
| pub fn codegen_fat_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 fat ptr binop"); |
| } |
| } |
| } |
| |
| pub fn codegen_scalar_checked_binop( |
| &mut self, |
| bx: &mut Bx, |
| op: mir::BinOp, |
| lhs: Bx::Value, |
| rhs: Bx::Value, |
| input_ty: Ty<'tcx>, |
| ) -> OperandValue<Bx::Value> { |
| // This case can currently arise only from functions marked |
| // with #[rustc_inherit_overflow_checks] and inlined from |
| // another crate (mostly core::num generic/#[inline] fns), |
| // while the current crate doesn't use overflow checks. |
| if !bx.cx().check_overflow() { |
| let val = self.codegen_scalar_binop(bx, op, lhs, rhs, input_ty); |
| return OperandValue::Pair(val, bx.cx().const_bool(false)); |
| } |
| |
| 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) |
| } |
| mir::BinOp::Shl | mir::BinOp::Shr => { |
| let lhs_llty = bx.cx().val_ty(lhs); |
| let rhs_llty = bx.cx().val_ty(rhs); |
| let invert_mask = common::shift_mask_val(bx, lhs_llty, rhs_llty, true); |
| let outer_bits = bx.and(rhs, invert_mask); |
| |
| let of = bx.icmp(IntPredicate::IntNE, outer_bits, bx.cx().const_null(rhs_llty)); |
| let val = self.codegen_scalar_binop(bx, op, lhs, rhs, input_ty); |
| |
| (val, of) |
| } |
| _ => bug!("Operator `{:?}` is not a checkable operator", op), |
| }; |
| |
| OperandValue::Pair(val, of) |
| } |
| } |
| |
| impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { |
| pub fn rvalue_creates_operand(&self, rvalue: &mir::Rvalue<'tcx>, span: Span) -> bool { |
| match *rvalue { |
| mir::Rvalue::Ref(..) | |
| mir::Rvalue::AddressOf(..) | |
| mir::Rvalue::Len(..) | |
| mir::Rvalue::Cast(..) | // (*) |
| mir::Rvalue::BinaryOp(..) | |
| mir::Rvalue::CheckedBinaryOp(..) | |
| mir::Rvalue::UnaryOp(..) | |
| mir::Rvalue::Discriminant(..) | |
| mir::Rvalue::NullaryOp(..) | |
| mir::Rvalue::ThreadLocalRef(_) | |
| mir::Rvalue::Use(..) => // (*) |
| true, |
| mir::Rvalue::Repeat(..) | |
| mir::Rvalue::Aggregate(..) => { |
| let ty = rvalue.ty(self.mir, self.cx.tcx()); |
| let ty = self.monomorphize(ty); |
| self.cx.spanned_layout_of(ty, span).is_zst() |
| } |
| } |
| |
| // (*) this is only true if the type is suitable |
| } |
| } |
| |
| fn cast_float_to_int<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( |
| bx: &mut Bx, |
| signed: bool, |
| x: Bx::Value, |
| float_ty: Bx::Type, |
| int_ty: Bx::Type, |
| ) -> Bx::Value { |
| if let Some(false) = bx.cx().sess().opts.debugging_opts.saturating_float_casts { |
| return if signed { bx.fptosi(x, int_ty) } else { bx.fptoui(x, int_ty) }; |
| } |
| |
| let try_sat_result = if signed { bx.fptosi_sat(x, int_ty) } else { bx.fptoui_sat(x, int_ty) }; |
| if let Some(try_sat_result) = try_sat_result { |
| return try_sat_result; |
| } |
| |
| let int_width = bx.cx().int_width(int_ty); |
| let float_width = bx.cx().float_width(float_ty); |
| // LLVM's fpto[su]i returns undef when the input x is infinite, NaN, or does not fit into the |
| // destination integer type after rounding towards zero. This `undef` value can cause UB in |
| // safe code (see issue #10184), so we implement a saturating conversion on top of it: |
| // Semantically, the mathematical value of the input is rounded towards zero to the next |
| // mathematical integer, and then the result is clamped into the range of the destination |
| // integer type. Positive and negative infinity are mapped to the maximum and minimum value of |
| // the destination integer type. NaN is mapped to 0. |
| // |
| // Define f_min and f_max as the largest and smallest (finite) floats that are exactly equal to |
| // a value representable in int_ty. |
| // They are exactly equal to int_ty::{MIN,MAX} if float_ty has enough significand bits. |
| // Otherwise, int_ty::MAX must be rounded towards zero, as it is one less than a power of two. |
| // int_ty::MIN, however, is either zero or a negative power of two and is thus exactly |
| // representable. Note that this only works if float_ty's exponent range is sufficiently large. |
| // f16 or 256 bit integers would break this property. Right now the smallest float type is f32 |
| // with exponents ranging up to 127, which is barely enough for i128::MIN = -2^127. |
| // On the other hand, f_max works even if int_ty::MAX is greater than float_ty::MAX. Because |
| // we're rounding towards zero, we just get float_ty::MAX (which is always an integer). |
| // This already happens today with u128::MAX = 2^128 - 1 > f32::MAX. |
| let int_max = |signed: bool, int_width: u64| -> u128 { |
| let shift_amount = 128 - int_width; |
| if signed { i128::MAX as u128 >> shift_amount } else { u128::MAX >> shift_amount } |
| }; |
| let int_min = |signed: bool, int_width: u64| -> i128 { |
| if signed { i128::MIN >> (128 - int_width) } else { 0 } |
| }; |
| |
| let compute_clamp_bounds_single = |signed: bool, int_width: u64| -> (u128, u128) { |
| let rounded_min = ieee::Single::from_i128_r(int_min(signed, int_width), Round::TowardZero); |
| assert_eq!(rounded_min.status, Status::OK); |
| let rounded_max = ieee::Single::from_u128_r(int_max(signed, int_width), Round::TowardZero); |
| assert!(rounded_max.value.is_finite()); |
| (rounded_min.value.to_bits(), rounded_max.value.to_bits()) |
| }; |
| let compute_clamp_bounds_double = |signed: bool, int_width: u64| -> (u128, u128) { |
| let rounded_min = ieee::Double::from_i128_r(int_min(signed, int_width), Round::TowardZero); |
| assert_eq!(rounded_min.status, Status::OK); |
| let rounded_max = ieee::Double::from_u128_r(int_max(signed, int_width), Round::TowardZero); |
| assert!(rounded_max.value.is_finite()); |
| (rounded_min.value.to_bits(), rounded_max.value.to_bits()) |
| }; |
| |
| let mut float_bits_to_llval = |bits| { |
| let bits_llval = match float_width { |
| 32 => bx.cx().const_u32(bits as u32), |
| 64 => bx.cx().const_u64(bits as u64), |
| n => bug!("unsupported float width {}", n), |
| }; |
| bx.bitcast(bits_llval, float_ty) |
| }; |
| let (f_min, f_max) = match float_width { |
| 32 => compute_clamp_bounds_single(signed, int_width), |
| 64 => compute_clamp_bounds_double(signed, int_width), |
| n => bug!("unsupported float width {}", n), |
| }; |
| let f_min = float_bits_to_llval(f_min); |
| let f_max = float_bits_to_llval(f_max); |
| // To implement saturation, we perform the following steps: |
| // |
| // 1. Cast x to an integer with fpto[su]i. This may result in undef. |
| // 2. Compare x to f_min and f_max, and use the comparison results to select: |
| // a) int_ty::MIN if x < f_min or x is NaN |
| // b) int_ty::MAX if x > f_max |
| // c) the result of fpto[su]i otherwise |
| // 3. If x is NaN, return 0.0, otherwise return the result of step 2. |
| // |
| // This avoids resulting undef because values in range [f_min, f_max] by definition fit into the |
| // destination type. It creates an undef temporary, but *producing* undef is not UB. Our use of |
| // undef does not introduce any non-determinism either. |
| // More importantly, the above procedure correctly implements saturating conversion. |
| // Proof (sketch): |
| // If x is NaN, 0 is returned by definition. |
| // Otherwise, x is finite or infinite and thus can be compared with f_min and f_max. |
| // This yields three cases to consider: |
| // (1) if x in [f_min, f_max], the result of fpto[su]i is returned, which agrees with |
| // saturating conversion for inputs in that range. |
| // (2) if x > f_max, then x is larger than int_ty::MAX. This holds even if f_max is rounded |
| // (i.e., if f_max < int_ty::MAX) because in those cases, nextUp(f_max) is already larger |
| // than int_ty::MAX. Because x is larger than int_ty::MAX, the return value of int_ty::MAX |
| // is correct. |
| // (3) if x < f_min, then x is smaller than int_ty::MIN. As shown earlier, f_min exactly equals |
| // int_ty::MIN and therefore the return value of int_ty::MIN is correct. |
| // QED. |
| |
| let int_max = bx.cx().const_uint_big(int_ty, int_max(signed, int_width)); |
| let int_min = bx.cx().const_uint_big(int_ty, int_min(signed, int_width) as u128); |
| let zero = bx.cx().const_uint(int_ty, 0); |
| |
| // Step 1 ... |
| let fptosui_result = if signed { bx.fptosi(x, int_ty) } else { bx.fptoui(x, int_ty) }; |
| let less_or_nan = bx.fcmp(RealPredicate::RealULT, x, f_min); |
| let greater = bx.fcmp(RealPredicate::RealOGT, x, f_max); |
| |
| // Step 2: We use two comparisons and two selects, with %s1 being the |
| // result: |
| // %less_or_nan = fcmp ult %x, %f_min |
| // %greater = fcmp olt %x, %f_max |
| // %s0 = select %less_or_nan, int_ty::MIN, %fptosi_result |
| // %s1 = select %greater, int_ty::MAX, %s0 |
| // Note that %less_or_nan uses an *unordered* comparison. This |
| // comparison is true if the operands are not comparable (i.e., if x is |
| // NaN). The unordered comparison ensures that s1 becomes int_ty::MIN if |
| // x is NaN. |
| // |
| // Performance note: Unordered comparison can be lowered to a "flipped" |
| // comparison and a negation, and the negation can be merged into the |
| // select. Therefore, it not necessarily any more expensive than a |
| // ordered ("normal") comparison. Whether these optimizations will be |
| // performed is ultimately up to the backend, but at least x86 does |
| // perform them. |
| let s0 = bx.select(less_or_nan, int_min, fptosui_result); |
| let s1 = bx.select(greater, int_max, s0); |
| |
| // Step 3: NaN replacement. |
| // For unsigned types, the above step already yielded int_ty::MIN == 0 if x is NaN. |
| // Therefore we only need to execute this step for signed integer types. |
| if signed { |
| // LLVM has no isNaN predicate, so we use (x == x) instead |
| let cmp = bx.fcmp(RealPredicate::RealOEQ, x, x); |
| bx.select(cmp, s1, zero) |
| } else { |
| s1 |
| } |
| } |
