1 use super::operand::{OperandRef, OperandValue};
2 use super::place::PlaceRef;
3 use super::{FunctionCx, LocalRef};
6 use crate::common::{self, IntPredicate};
10 use rustc_middle::mir;
11 use rustc_middle::mir::Operand;
12 use rustc_middle::ty::cast::{CastTy, IntTy};
13 use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf};
14 use rustc_middle::ty::{self, adjustment::PointerCast, Instance, Ty, TyCtxt};
15 use rustc_span::source_map::{Span, DUMMY_SP};
17 impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
18 #[instrument(level = "trace", skip(self, bx))]
19 pub fn codegen_rvalue(
22 dest: PlaceRef<'tcx, Bx::Value>,
23 rvalue: &mir::Rvalue<'tcx>,
26 mir::Rvalue::Use(ref operand) => {
27 let cg_operand = self.codegen_operand(&mut bx, operand);
28 // FIXME: consider not copying constants through stack. (Fixable by codegen'ing
29 // constants into `OperandValue::Ref`; why don’t we do that yet if we don’t?)
30 cg_operand.val.store(&mut bx, dest);
34 mir::Rvalue::Cast(mir::CastKind::Pointer(PointerCast::Unsize), ref source, _) => {
35 // The destination necessarily contains a fat pointer, so if
36 // it's a scalar pair, it's a fat pointer or newtype thereof.
37 if bx.cx().is_backend_scalar_pair(dest.layout) {
38 // Into-coerce of a thin pointer to a fat pointer -- just
39 // use the operand path.
40 let (mut bx, temp) = self.codegen_rvalue_operand(bx, rvalue);
41 temp.val.store(&mut bx, dest);
45 // Unsize of a nontrivial struct. I would prefer for
46 // this to be eliminated by MIR building, but
47 // `CoerceUnsized` can be passed by a where-clause,
48 // so the (generic) MIR may not be able to expand it.
49 let operand = self.codegen_operand(&mut bx, source);
51 OperandValue::Pair(..) | OperandValue::Immediate(_) => {
52 // Unsize from an immediate structure. We don't
53 // really need a temporary alloca here, but
54 // avoiding it would require us to have
55 // `coerce_unsized_into` use `extractvalue` to
56 // index into the struct, and this case isn't
57 // important enough for it.
58 debug!("codegen_rvalue: creating ugly alloca");
59 let scratch = PlaceRef::alloca(&mut bx, operand.layout);
60 scratch.storage_live(&mut bx);
61 operand.val.store(&mut bx, scratch);
62 base::coerce_unsized_into(&mut bx, scratch, dest);
63 scratch.storage_dead(&mut bx);
65 OperandValue::Ref(llref, None, align) => {
66 let source = PlaceRef::new_sized_aligned(llref, operand.layout, align);
67 base::coerce_unsized_into(&mut bx, source, dest);
69 OperandValue::Ref(_, Some(_), _) => {
70 bug!("unsized coercion on an unsized rvalue");
76 mir::Rvalue::Repeat(ref elem, count) => {
77 let cg_elem = self.codegen_operand(&mut bx, elem);
79 // Do not generate the loop for zero-sized elements or empty arrays.
80 if dest.layout.is_zst() {
84 if let OperandValue::Immediate(v) = cg_elem.val {
85 let zero = bx.const_usize(0);
86 let start = dest.project_index(&mut bx, zero).llval;
87 let size = bx.const_usize(dest.layout.size.bytes());
89 // Use llvm.memset.p0i8.* to initialize all zero arrays
90 if bx.cx().const_to_opt_u128(v, false) == Some(0) {
91 let fill = bx.cx().const_u8(0);
92 bx.memset(start, fill, size, dest.align, MemFlags::empty());
96 // Use llvm.memset.p0i8.* to initialize byte arrays
97 let v = bx.from_immediate(v);
98 if bx.cx().val_ty(v) == bx.cx().type_i8() {
99 bx.memset(start, v, size, dest.align, MemFlags::empty());
105 self.monomorphize(count).eval_usize(bx.cx().tcx(), ty::ParamEnv::reveal_all());
107 bx.write_operand_repeatedly(cg_elem, count, dest)
110 mir::Rvalue::Aggregate(ref kind, ref operands) => {
111 let (dest, active_field_index) = match **kind {
112 mir::AggregateKind::Adt(adt_did, variant_index, _, _, active_field_index) => {
113 dest.codegen_set_discr(&mut bx, variant_index);
114 if bx.tcx().adt_def(adt_did).is_enum() {
115 (dest.project_downcast(&mut bx, variant_index), active_field_index)
117 (dest, active_field_index)
122 for (i, operand) in operands.iter().enumerate() {
123 let op = self.codegen_operand(&mut bx, operand);
124 // Do not generate stores and GEPis for zero-sized fields.
125 if !op.layout.is_zst() {
126 let field_index = active_field_index.unwrap_or(i);
127 let field = if let mir::AggregateKind::Array(_) = **kind {
128 let llindex = bx.cx().const_usize(field_index as u64);
129 dest.project_index(&mut bx, llindex)
131 dest.project_field(&mut bx, field_index)
133 op.val.store(&mut bx, field);
140 assert!(self.rvalue_creates_operand(rvalue, DUMMY_SP));
141 let (mut bx, temp) = self.codegen_rvalue_operand(bx, rvalue);
142 temp.val.store(&mut bx, dest);
148 pub fn codegen_rvalue_unsized(
151 indirect_dest: PlaceRef<'tcx, Bx::Value>,
152 rvalue: &mir::Rvalue<'tcx>,
155 "codegen_rvalue_unsized(indirect_dest.llval={:?}, rvalue={:?})",
156 indirect_dest.llval, rvalue
160 mir::Rvalue::Use(ref operand) => {
161 let cg_operand = self.codegen_operand(&mut bx, operand);
162 cg_operand.val.store_unsized(&mut bx, indirect_dest);
166 _ => bug!("unsized assignment other than `Rvalue::Use`"),
170 pub fn codegen_rvalue_operand(
173 rvalue: &mir::Rvalue<'tcx>,
174 ) -> (Bx, OperandRef<'tcx, Bx::Value>) {
176 self.rvalue_creates_operand(rvalue, DUMMY_SP),
177 "cannot codegen {:?} to operand",
182 mir::Rvalue::Cast(ref kind, ref source, mir_cast_ty) => {
183 let operand = self.codegen_operand(&mut bx, source);
184 debug!("cast operand is {:?}", operand);
185 let cast = bx.cx().layout_of(self.monomorphize(mir_cast_ty));
187 let val = match *kind {
188 mir::CastKind::PointerExposeAddress => {
189 assert!(bx.cx().is_backend_immediate(cast));
190 let llptr = operand.immediate();
191 let llcast_ty = bx.cx().immediate_backend_type(cast);
192 let lladdr = bx.ptrtoint(llptr, llcast_ty);
193 OperandValue::Immediate(lladdr)
195 mir::CastKind::Pointer(PointerCast::ReifyFnPointer) => {
196 match *operand.layout.ty.kind() {
197 ty::FnDef(def_id, substs) => {
198 let instance = ty::Instance::resolve_for_fn_ptr(
200 ty::ParamEnv::reveal_all(),
205 .polymorphize(bx.cx().tcx());
206 OperandValue::Immediate(bx.get_fn_addr(instance))
208 _ => bug!("{} cannot be reified to a fn ptr", operand.layout.ty),
211 mir::CastKind::Pointer(PointerCast::ClosureFnPointer(_)) => {
212 match *operand.layout.ty.kind() {
213 ty::Closure(def_id, substs) => {
214 let instance = Instance::resolve_closure(
218 ty::ClosureKind::FnOnce,
220 .expect("failed to normalize and resolve closure during codegen")
221 .polymorphize(bx.cx().tcx());
222 OperandValue::Immediate(bx.cx().get_fn_addr(instance))
224 _ => bug!("{} cannot be cast to a fn ptr", operand.layout.ty),
227 mir::CastKind::Pointer(PointerCast::UnsafeFnPointer) => {
228 // This is a no-op at the LLVM level.
231 mir::CastKind::Pointer(PointerCast::Unsize) => {
232 assert!(bx.cx().is_backend_scalar_pair(cast));
233 let (lldata, llextra) = match operand.val {
234 OperandValue::Pair(lldata, llextra) => {
235 // unsize from a fat pointer -- this is a
236 // "trait-object-to-supertrait" coercion.
237 (lldata, Some(llextra))
239 OperandValue::Immediate(lldata) => {
243 OperandValue::Ref(..) => {
244 bug!("by-ref operand {:?} in `codegen_rvalue_operand`", operand);
247 let (lldata, llextra) =
248 base::unsize_ptr(&mut bx, lldata, operand.layout.ty, cast.ty, llextra);
249 OperandValue::Pair(lldata, llextra)
251 mir::CastKind::Pointer(PointerCast::MutToConstPointer)
252 | mir::CastKind::PtrToPtr
253 if bx.cx().is_backend_scalar_pair(operand.layout) =>
255 if let OperandValue::Pair(data_ptr, meta) = operand.val {
256 if bx.cx().is_backend_scalar_pair(cast) {
257 let data_cast = bx.pointercast(
259 bx.cx().scalar_pair_element_backend_type(cast, 0, true),
261 OperandValue::Pair(data_cast, meta)
264 // Cast of fat-ptr to thin-ptr is an extraction of data-ptr and
265 // pointer-cast of that pointer to desired pointer type.
266 let llcast_ty = bx.cx().immediate_backend_type(cast);
267 let llval = bx.pointercast(data_ptr, llcast_ty);
268 OperandValue::Immediate(llval)
271 bug!("unexpected non-pair operand");
274 mir::CastKind::DynStar => {
275 let (lldata, llextra) = match operand.val {
276 OperandValue::Ref(_, _, _) => todo!(),
277 OperandValue::Immediate(v) => (v, None),
278 OperandValue::Pair(v, l) => (v, Some(l)),
280 let (lldata, llextra) =
281 base::cast_to_dyn_star(&mut bx, lldata, operand.layout, cast.ty, llextra);
282 OperandValue::Pair(lldata, llextra)
284 mir::CastKind::Pointer(
285 PointerCast::MutToConstPointer | PointerCast::ArrayToPointer,
287 | mir::CastKind::IntToInt
288 | mir::CastKind::FloatToInt
289 | mir::CastKind::FloatToFloat
290 | mir::CastKind::IntToFloat
291 | mir::CastKind::PtrToPtr
292 | mir::CastKind::FnPtrToPtr
294 // Since int2ptr can have arbitrary integer types as input (so we have to do
295 // sign extension and all that), it is currently best handled in the same code
296 // path as the other integer-to-X casts.
297 | mir::CastKind::PointerFromExposedAddress => {
298 assert!(bx.cx().is_backend_immediate(cast));
299 let ll_t_out = bx.cx().immediate_backend_type(cast);
300 if operand.layout.abi.is_uninhabited() {
301 let val = OperandValue::Immediate(bx.cx().const_undef(ll_t_out));
302 return (bx, OperandRef { val, layout: cast });
305 CastTy::from_ty(operand.layout.ty).expect("bad input type for cast");
306 let r_t_out = CastTy::from_ty(cast.ty).expect("bad output type for cast");
307 let ll_t_in = bx.cx().immediate_backend_type(operand.layout);
308 let llval = operand.immediate();
310 let newval = match (r_t_in, r_t_out) {
311 (CastTy::Int(i), CastTy::Int(_)) => {
312 bx.intcast(llval, ll_t_out, i.is_signed())
314 (CastTy::Float, CastTy::Float) => {
315 let srcsz = bx.cx().float_width(ll_t_in);
316 let dstsz = bx.cx().float_width(ll_t_out);
318 bx.fpext(llval, ll_t_out)
319 } else if srcsz > dstsz {
320 bx.fptrunc(llval, ll_t_out)
325 (CastTy::Int(i), CastTy::Float) => {
327 bx.sitofp(llval, ll_t_out)
329 bx.uitofp(llval, ll_t_out)
332 (CastTy::Ptr(_) | CastTy::FnPtr, CastTy::Ptr(_)) => {
333 bx.pointercast(llval, ll_t_out)
335 (CastTy::Int(i), CastTy::Ptr(_)) => {
337 bx.intcast(llval, bx.cx().type_isize(), i.is_signed());
338 bx.inttoptr(usize_llval, ll_t_out)
340 (CastTy::Float, CastTy::Int(IntTy::I)) => {
341 bx.cast_float_to_int(true, llval, ll_t_out)
343 (CastTy::Float, CastTy::Int(_)) => {
344 bx.cast_float_to_int(false, llval, ll_t_out)
346 _ => bug!("unsupported cast: {:?} to {:?}", operand.layout.ty, cast.ty),
348 OperandValue::Immediate(newval)
351 (bx, OperandRef { val, layout: cast })
354 mir::Rvalue::Ref(_, bk, place) => {
355 let mk_ref = move |tcx: TyCtxt<'tcx>, ty: Ty<'tcx>| {
357 tcx.lifetimes.re_erased,
358 ty::TypeAndMut { ty, mutbl: bk.to_mutbl_lossy() },
361 self.codegen_place_to_pointer(bx, place, mk_ref)
364 mir::Rvalue::CopyForDeref(place) => {
365 let operand = self.codegen_operand(&mut bx, &Operand::Copy(place));
368 mir::Rvalue::AddressOf(mutability, place) => {
369 let mk_ptr = move |tcx: TyCtxt<'tcx>, ty: Ty<'tcx>| {
370 tcx.mk_ptr(ty::TypeAndMut { ty, mutbl: mutability })
372 self.codegen_place_to_pointer(bx, place, mk_ptr)
375 mir::Rvalue::Len(place) => {
376 let size = self.evaluate_array_len(&mut bx, place);
377 let operand = OperandRef {
378 val: OperandValue::Immediate(size),
379 layout: bx.cx().layout_of(bx.tcx().types.usize),
384 mir::Rvalue::BinaryOp(op, box (ref lhs, ref rhs)) => {
385 let lhs = self.codegen_operand(&mut bx, lhs);
386 let rhs = self.codegen_operand(&mut bx, rhs);
387 let llresult = match (lhs.val, rhs.val) {
389 OperandValue::Pair(lhs_addr, lhs_extra),
390 OperandValue::Pair(rhs_addr, rhs_extra),
391 ) => self.codegen_fat_ptr_binop(
401 (OperandValue::Immediate(lhs_val), OperandValue::Immediate(rhs_val)) => {
402 self.codegen_scalar_binop(&mut bx, op, lhs_val, rhs_val, lhs.layout.ty)
407 let operand = OperandRef {
408 val: OperandValue::Immediate(llresult),
409 layout: bx.cx().layout_of(op.ty(bx.tcx(), lhs.layout.ty, rhs.layout.ty)),
413 mir::Rvalue::CheckedBinaryOp(op, box (ref lhs, ref rhs)) => {
414 let lhs = self.codegen_operand(&mut bx, lhs);
415 let rhs = self.codegen_operand(&mut bx, rhs);
416 let result = self.codegen_scalar_checked_binop(
423 let val_ty = op.ty(bx.tcx(), lhs.layout.ty, rhs.layout.ty);
424 let operand_ty = bx.tcx().intern_tup(&[val_ty, bx.tcx().types.bool]);
425 let operand = OperandRef { val: result, layout: bx.cx().layout_of(operand_ty) };
430 mir::Rvalue::UnaryOp(op, ref operand) => {
431 let operand = self.codegen_operand(&mut bx, operand);
432 let lloperand = operand.immediate();
433 let is_float = operand.layout.ty.is_floating_point();
434 let llval = match op {
435 mir::UnOp::Not => bx.not(lloperand),
444 (bx, OperandRef { val: OperandValue::Immediate(llval), layout: operand.layout })
447 mir::Rvalue::Discriminant(ref place) => {
448 let discr_ty = rvalue.ty(self.mir, bx.tcx());
449 let discr_ty = self.monomorphize(discr_ty);
451 .codegen_place(&mut bx, place.as_ref())
452 .codegen_get_discr(&mut bx, discr_ty);
456 val: OperandValue::Immediate(discr),
457 layout: self.cx.layout_of(discr_ty),
462 mir::Rvalue::NullaryOp(null_op, ty) => {
463 let ty = self.monomorphize(ty);
464 assert!(bx.cx().type_is_sized(ty));
465 let layout = bx.cx().layout_of(ty);
466 let val = match null_op {
467 mir::NullOp::SizeOf => layout.size.bytes(),
468 mir::NullOp::AlignOf => layout.align.abi.bytes(),
470 let val = bx.cx().const_usize(val);
471 let tcx = self.cx.tcx();
475 val: OperandValue::Immediate(val),
476 layout: self.cx.layout_of(tcx.types.usize),
481 mir::Rvalue::ThreadLocalRef(def_id) => {
482 assert!(bx.cx().tcx().is_static(def_id));
483 let static_ = bx.get_static(def_id);
484 let layout = bx.layout_of(bx.cx().tcx().static_ptr_ty(def_id));
485 let operand = OperandRef::from_immediate_or_packed_pair(&mut bx, static_, layout);
488 mir::Rvalue::Use(ref operand) => {
489 let operand = self.codegen_operand(&mut bx, operand);
492 mir::Rvalue::Repeat(..) | mir::Rvalue::Aggregate(..) => {
493 // According to `rvalue_creates_operand`, only ZST
494 // aggregate rvalues are allowed to be operands.
495 let ty = rvalue.ty(self.mir, self.cx.tcx());
497 OperandRef::new_zst(&mut bx, self.cx.layout_of(self.monomorphize(ty)));
500 mir::Rvalue::ShallowInitBox(ref operand, content_ty) => {
501 let operand = self.codegen_operand(&mut bx, operand);
502 let lloperand = operand.immediate();
504 let content_ty = self.monomorphize(content_ty);
505 let box_layout = bx.cx().layout_of(bx.tcx().mk_box(content_ty));
506 let llty_ptr = bx.cx().backend_type(box_layout);
508 let val = bx.pointercast(lloperand, llty_ptr);
509 let operand = OperandRef { val: OperandValue::Immediate(val), layout: box_layout };
515 fn evaluate_array_len(&mut self, bx: &mut Bx, place: mir::Place<'tcx>) -> Bx::Value {
516 // ZST are passed as operands and require special handling
517 // because codegen_place() panics if Local is operand.
518 if let Some(index) = place.as_local() {
519 if let LocalRef::Operand(Some(op)) = self.locals[index] {
520 if let ty::Array(_, n) = op.layout.ty.kind() {
521 let n = n.eval_usize(bx.cx().tcx(), ty::ParamEnv::reveal_all());
522 return bx.cx().const_usize(n);
526 // use common size calculation for non zero-sized types
527 let cg_value = self.codegen_place(bx, place.as_ref());
528 cg_value.len(bx.cx())
531 /// Codegen an `Rvalue::AddressOf` or `Rvalue::Ref`
532 fn codegen_place_to_pointer(
535 place: mir::Place<'tcx>,
536 mk_ptr_ty: impl FnOnce(TyCtxt<'tcx>, Ty<'tcx>) -> Ty<'tcx>,
537 ) -> (Bx, OperandRef<'tcx, Bx::Value>) {
538 let cg_place = self.codegen_place(&mut bx, place.as_ref());
540 let ty = cg_place.layout.ty;
542 // Note: places are indirect, so storing the `llval` into the
543 // destination effectively creates a reference.
544 let val = if !bx.cx().type_has_metadata(ty) {
545 OperandValue::Immediate(cg_place.llval)
547 OperandValue::Pair(cg_place.llval, cg_place.llextra.unwrap())
549 (bx, OperandRef { val, layout: self.cx.layout_of(mk_ptr_ty(self.cx.tcx(), ty)) })
552 pub fn codegen_scalar_binop(
560 let is_float = input_ty.is_floating_point();
561 let is_signed = input_ty.is_signed();
587 } else if is_signed {
596 } else if is_signed {
602 mir::BinOp::BitOr => bx.or(lhs, rhs),
603 mir::BinOp::BitAnd => bx.and(lhs, rhs),
604 mir::BinOp::BitXor => bx.xor(lhs, rhs),
605 mir::BinOp::Offset => {
606 let pointee_type = input_ty
608 .unwrap_or_else(|| bug!("deref of non-pointer {:?}", input_ty))
610 let llty = bx.cx().backend_type(bx.cx().layout_of(pointee_type));
611 bx.inbounds_gep(llty, lhs, &[rhs])
613 mir::BinOp::Shl => common::build_unchecked_lshift(bx, lhs, rhs),
614 mir::BinOp::Shr => common::build_unchecked_rshift(bx, input_ty, lhs, rhs),
620 | mir::BinOp::Ge => {
622 bx.fcmp(base::bin_op_to_fcmp_predicate(op.to_hir_binop()), lhs, rhs)
624 bx.icmp(base::bin_op_to_icmp_predicate(op.to_hir_binop(), is_signed), lhs, rhs)
630 pub fn codegen_fat_ptr_binop(
635 lhs_extra: Bx::Value,
637 rhs_extra: Bx::Value,
642 let lhs = bx.icmp(IntPredicate::IntEQ, lhs_addr, rhs_addr);
643 let rhs = bx.icmp(IntPredicate::IntEQ, lhs_extra, rhs_extra);
647 let lhs = bx.icmp(IntPredicate::IntNE, lhs_addr, rhs_addr);
648 let rhs = bx.icmp(IntPredicate::IntNE, lhs_extra, rhs_extra);
651 mir::BinOp::Le | mir::BinOp::Lt | mir::BinOp::Ge | mir::BinOp::Gt => {
652 // a OP b ~ a.0 STRICT(OP) b.0 | (a.0 == b.0 && a.1 OP a.1)
653 let (op, strict_op) = match op {
654 mir::BinOp::Lt => (IntPredicate::IntULT, IntPredicate::IntULT),
655 mir::BinOp::Le => (IntPredicate::IntULE, IntPredicate::IntULT),
656 mir::BinOp::Gt => (IntPredicate::IntUGT, IntPredicate::IntUGT),
657 mir::BinOp::Ge => (IntPredicate::IntUGE, IntPredicate::IntUGT),
660 let lhs = bx.icmp(strict_op, lhs_addr, rhs_addr);
661 let and_lhs = bx.icmp(IntPredicate::IntEQ, lhs_addr, rhs_addr);
662 let and_rhs = bx.icmp(op, lhs_extra, rhs_extra);
663 let rhs = bx.and(and_lhs, and_rhs);
667 bug!("unexpected fat ptr binop");
672 pub fn codegen_scalar_checked_binop(
679 ) -> OperandValue<Bx::Value> {
680 // This case can currently arise only from functions marked
681 // with #[rustc_inherit_overflow_checks] and inlined from
682 // another crate (mostly core::num generic/#[inline] fns),
683 // while the current crate doesn't use overflow checks.
684 if !bx.cx().check_overflow() {
685 let val = self.codegen_scalar_binop(bx, op, lhs, rhs, input_ty);
686 return OperandValue::Pair(val, bx.cx().const_bool(false));
689 let (val, of) = match op {
690 // These are checked using intrinsics
691 mir::BinOp::Add | mir::BinOp::Sub | mir::BinOp::Mul => {
693 mir::BinOp::Add => OverflowOp::Add,
694 mir::BinOp::Sub => OverflowOp::Sub,
695 mir::BinOp::Mul => OverflowOp::Mul,
698 bx.checked_binop(oop, input_ty, lhs, rhs)
700 mir::BinOp::Shl | mir::BinOp::Shr => {
701 let lhs_llty = bx.cx().val_ty(lhs);
702 let rhs_llty = bx.cx().val_ty(rhs);
703 let invert_mask = common::shift_mask_val(bx, lhs_llty, rhs_llty, true);
704 let outer_bits = bx.and(rhs, invert_mask);
706 let of = bx.icmp(IntPredicate::IntNE, outer_bits, bx.cx().const_null(rhs_llty));
707 let val = self.codegen_scalar_binop(bx, op, lhs, rhs, input_ty);
711 _ => bug!("Operator `{:?}` is not a checkable operator", op),
714 OperandValue::Pair(val, of)
718 impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
719 pub fn rvalue_creates_operand(&self, rvalue: &mir::Rvalue<'tcx>, span: Span) -> bool {
721 mir::Rvalue::Ref(..) |
722 mir::Rvalue::CopyForDeref(..) |
723 mir::Rvalue::AddressOf(..) |
724 mir::Rvalue::Len(..) |
725 mir::Rvalue::Cast(..) | // (*)
726 mir::Rvalue::ShallowInitBox(..) | // (*)
727 mir::Rvalue::BinaryOp(..) |
728 mir::Rvalue::CheckedBinaryOp(..) |
729 mir::Rvalue::UnaryOp(..) |
730 mir::Rvalue::Discriminant(..) |
731 mir::Rvalue::NullaryOp(..) |
732 mir::Rvalue::ThreadLocalRef(_) |
733 mir::Rvalue::Use(..) => // (*)
735 mir::Rvalue::Repeat(..) |
736 mir::Rvalue::Aggregate(..) => {
737 let ty = rvalue.ty(self.mir, self.cx.tcx());
738 let ty = self.monomorphize(ty);
739 self.cx.spanned_layout_of(ty, span).is_zst()
743 // (*) this is only true if the type is suitable