1 use super::operand::{OperandRef, OperandValue};
2 use super::place::PlaceRef;
3 use super::{FunctionCx, LocalRef};
6 use crate::common::{self, IntPredicate};
7 use crate::meth::get_vtable;
11 use rustc_middle::mir;
12 use rustc_middle::mir::Operand;
13 use rustc_middle::ty::cast::{CastTy, IntTy};
14 use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf};
15 use rustc_middle::ty::{self, adjustment::PointerCast, Instance, Ty, TyCtxt};
16 use rustc_span::source_map::{Span, DUMMY_SP};
17 use rustc_target::abi::Size;
19 impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
20 #[instrument(level = "trace", skip(self, bx))]
21 pub fn codegen_rvalue(
24 dest: PlaceRef<'tcx, Bx::Value>,
25 rvalue: &mir::Rvalue<'tcx>,
28 mir::Rvalue::Use(ref operand) => {
29 let cg_operand = self.codegen_operand(&mut bx, operand);
30 // FIXME: consider not copying constants through stack. (Fixable by codegen'ing
31 // constants into `OperandValue::Ref`; why don’t we do that yet if we don’t?)
32 cg_operand.val.store(&mut bx, dest);
36 mir::Rvalue::Cast(mir::CastKind::Pointer(PointerCast::Unsize), ref source, _) => {
37 // The destination necessarily contains a fat pointer, so if
38 // it's a scalar pair, it's a fat pointer or newtype thereof.
39 if bx.cx().is_backend_scalar_pair(dest.layout) {
40 // Into-coerce of a thin pointer to a fat pointer -- just
41 // use the operand path.
42 let (mut bx, temp) = self.codegen_rvalue_operand(bx, rvalue);
43 temp.val.store(&mut bx, dest);
47 // Unsize of a nontrivial struct. I would prefer for
48 // this to be eliminated by MIR building, but
49 // `CoerceUnsized` can be passed by a where-clause,
50 // so the (generic) MIR may not be able to expand it.
51 let operand = self.codegen_operand(&mut bx, source);
53 OperandValue::Pair(..) | OperandValue::Immediate(_) => {
54 // Unsize from an immediate structure. We don't
55 // really need a temporary alloca here, but
56 // avoiding it would require us to have
57 // `coerce_unsized_into` use `extractvalue` to
58 // index into the struct, and this case isn't
59 // important enough for it.
60 debug!("codegen_rvalue: creating ugly alloca");
61 let scratch = PlaceRef::alloca(&mut bx, operand.layout);
62 scratch.storage_live(&mut bx);
63 operand.val.store(&mut bx, scratch);
64 base::coerce_unsized_into(&mut bx, scratch, dest);
65 scratch.storage_dead(&mut bx);
67 OperandValue::Ref(llref, None, align) => {
68 let source = PlaceRef::new_sized_aligned(llref, operand.layout, align);
69 base::coerce_unsized_into(&mut bx, source, dest);
71 OperandValue::Ref(_, Some(_), _) => {
72 bug!("unsized coercion on an unsized rvalue");
78 mir::Rvalue::Repeat(ref elem, count) => {
79 let cg_elem = self.codegen_operand(&mut bx, elem);
81 // Do not generate the loop for zero-sized elements or empty arrays.
82 if dest.layout.is_zst() {
86 if let OperandValue::Immediate(v) = cg_elem.val {
87 let zero = bx.const_usize(0);
88 let start = dest.project_index(&mut bx, zero).llval;
89 let size = bx.const_usize(dest.layout.size.bytes());
91 // Use llvm.memset.p0i8.* to initialize all zero arrays
92 if bx.cx().const_to_opt_u128(v, false) == Some(0) {
93 let fill = bx.cx().const_u8(0);
94 bx.memset(start, fill, size, dest.align, MemFlags::empty());
98 // Use llvm.memset.p0i8.* to initialize byte arrays
99 let v = bx.from_immediate(v);
100 if bx.cx().val_ty(v) == bx.cx().type_i8() {
101 bx.memset(start, v, size, dest.align, MemFlags::empty());
107 self.monomorphize(count).eval_usize(bx.cx().tcx(), ty::ParamEnv::reveal_all());
109 bx.write_operand_repeatedly(cg_elem, count, dest)
112 mir::Rvalue::Aggregate(ref kind, ref operands) => {
113 let (dest, active_field_index) = match **kind {
114 mir::AggregateKind::Adt(adt_did, variant_index, _, _, active_field_index) => {
115 dest.codegen_set_discr(&mut bx, variant_index);
116 if bx.tcx().adt_def(adt_did).is_enum() {
117 (dest.project_downcast(&mut bx, variant_index), active_field_index)
119 (dest, active_field_index)
124 for (i, operand) in operands.iter().enumerate() {
125 let op = self.codegen_operand(&mut bx, operand);
126 // Do not generate stores and GEPis for zero-sized fields.
127 if !op.layout.is_zst() {
128 let field_index = active_field_index.unwrap_or(i);
129 let field = if let mir::AggregateKind::Array(_) = **kind {
130 let llindex = bx.cx().const_usize(field_index as u64);
131 dest.project_index(&mut bx, llindex)
133 dest.project_field(&mut bx, field_index)
135 op.val.store(&mut bx, field);
142 assert!(self.rvalue_creates_operand(rvalue, DUMMY_SP));
143 let (mut bx, temp) = self.codegen_rvalue_operand(bx, rvalue);
144 temp.val.store(&mut bx, dest);
150 pub fn codegen_rvalue_unsized(
153 indirect_dest: PlaceRef<'tcx, Bx::Value>,
154 rvalue: &mir::Rvalue<'tcx>,
157 "codegen_rvalue_unsized(indirect_dest.llval={:?}, rvalue={:?})",
158 indirect_dest.llval, rvalue
162 mir::Rvalue::Use(ref operand) => {
163 let cg_operand = self.codegen_operand(&mut bx, operand);
164 cg_operand.val.store_unsized(&mut bx, indirect_dest);
168 _ => bug!("unsized assignment other than `Rvalue::Use`"),
172 pub fn codegen_rvalue_operand(
175 rvalue: &mir::Rvalue<'tcx>,
176 ) -> (Bx, OperandRef<'tcx, Bx::Value>) {
178 self.rvalue_creates_operand(rvalue, DUMMY_SP),
179 "cannot codegen {:?} to operand",
184 mir::Rvalue::Cast(ref kind, ref source, mir_cast_ty) => {
185 let operand = self.codegen_operand(&mut bx, source);
186 debug!("cast operand is {:?}", operand);
187 let cast = bx.cx().layout_of(self.monomorphize(mir_cast_ty));
189 let val = match *kind {
190 mir::CastKind::PointerExposeAddress => {
191 assert!(bx.cx().is_backend_immediate(cast));
192 let llptr = operand.immediate();
193 let llcast_ty = bx.cx().immediate_backend_type(cast);
194 let lladdr = bx.ptrtoint(llptr, llcast_ty);
195 OperandValue::Immediate(lladdr)
197 mir::CastKind::Pointer(PointerCast::ReifyFnPointer) => {
198 match *operand.layout.ty.kind() {
199 ty::FnDef(def_id, substs) => {
200 let instance = ty::Instance::resolve_for_fn_ptr(
202 ty::ParamEnv::reveal_all(),
207 .polymorphize(bx.cx().tcx());
208 OperandValue::Immediate(bx.get_fn_addr(instance))
210 _ => bug!("{} cannot be reified to a fn ptr", operand.layout.ty),
213 mir::CastKind::Pointer(PointerCast::ClosureFnPointer(_)) => {
214 match *operand.layout.ty.kind() {
215 ty::Closure(def_id, substs) => {
216 let instance = Instance::resolve_closure(
220 ty::ClosureKind::FnOnce,
222 .expect("failed to normalize and resolve closure during codegen")
223 .polymorphize(bx.cx().tcx());
224 OperandValue::Immediate(bx.cx().get_fn_addr(instance))
226 _ => bug!("{} cannot be cast to a fn ptr", operand.layout.ty),
229 mir::CastKind::Pointer(PointerCast::UnsafeFnPointer) => {
230 // This is a no-op at the LLVM level.
233 mir::CastKind::Pointer(PointerCast::Unsize) => {
234 assert!(bx.cx().is_backend_scalar_pair(cast));
235 let (lldata, llextra) = match operand.val {
236 OperandValue::Pair(lldata, llextra) => {
237 // unsize from a fat pointer -- this is a
238 // "trait-object-to-supertrait" coercion.
239 (lldata, Some(llextra))
241 OperandValue::Immediate(lldata) => {
245 OperandValue::Ref(..) => {
246 bug!("by-ref operand {:?} in `codegen_rvalue_operand`", operand);
249 let (lldata, llextra) =
250 base::unsize_ptr(&mut bx, lldata, operand.layout.ty, cast.ty, llextra);
251 OperandValue::Pair(lldata, llextra)
253 mir::CastKind::Pointer(PointerCast::MutToConstPointer)
254 | mir::CastKind::PtrToPtr
255 if bx.cx().is_backend_scalar_pair(operand.layout) =>
257 if let OperandValue::Pair(data_ptr, meta) = operand.val {
258 if bx.cx().is_backend_scalar_pair(cast) {
259 let data_cast = bx.pointercast(
261 bx.cx().scalar_pair_element_backend_type(cast, 0, true),
263 OperandValue::Pair(data_cast, meta)
266 // Cast of fat-ptr to thin-ptr is an extraction of data-ptr and
267 // pointer-cast of that pointer to desired pointer type.
268 let llcast_ty = bx.cx().immediate_backend_type(cast);
269 let llval = bx.pointercast(data_ptr, llcast_ty);
270 OperandValue::Immediate(llval)
273 bug!("unexpected non-pair operand");
276 mir::CastKind::DynStar => {
277 let data = match operand.val {
278 OperandValue::Ref(_, _, _) => todo!(),
279 OperandValue::Immediate(v) => v,
280 OperandValue::Pair(_, _) => todo!(),
283 if let ty::Dynamic(data, _, ty::DynStar) = cast.ty.kind() {
286 bug!("Only valid to do a DynStar cast into a DynStar type")
288 let vtable = get_vtable(bx.cx(), source.ty(self.mir, bx.tcx()), trait_ref);
289 let vtable = bx.pointercast(vtable, bx.cx().type_ptr_to(bx.cx().type_isize()));
290 // FIXME(dyn-star): this is probably not the best way to check if this is
291 // a pointer, and really we should ensure that the value is a suitable
292 // pointer earlier in the compilation process.
293 let data = match operand.layout.pointee_info_at(bx.cx(), Size::ZERO) {
294 Some(_) => bx.ptrtoint(data, bx.cx().type_isize()),
297 OperandValue::Pair(data, vtable)
299 mir::CastKind::Pointer(
300 PointerCast::MutToConstPointer | PointerCast::ArrayToPointer,
302 | mir::CastKind::IntToInt
303 | mir::CastKind::FloatToInt
304 | mir::CastKind::FloatToFloat
305 | mir::CastKind::IntToFloat
306 | mir::CastKind::PtrToPtr
307 | mir::CastKind::FnPtrToPtr
309 // Since int2ptr can have arbitrary integer types as input (so we have to do
310 // sign extension and all that), it is currently best handled in the same code
311 // path as the other integer-to-X casts.
312 | mir::CastKind::PointerFromExposedAddress => {
313 assert!(bx.cx().is_backend_immediate(cast));
314 let ll_t_out = bx.cx().immediate_backend_type(cast);
315 if operand.layout.abi.is_uninhabited() {
316 let val = OperandValue::Immediate(bx.cx().const_undef(ll_t_out));
317 return (bx, OperandRef { val, layout: cast });
320 CastTy::from_ty(operand.layout.ty).expect("bad input type for cast");
321 let r_t_out = CastTy::from_ty(cast.ty).expect("bad output type for cast");
322 let ll_t_in = bx.cx().immediate_backend_type(operand.layout);
323 let llval = operand.immediate();
325 let newval = match (r_t_in, r_t_out) {
326 (CastTy::Int(i), CastTy::Int(_)) => {
327 bx.intcast(llval, ll_t_out, i.is_signed())
329 (CastTy::Float, CastTy::Float) => {
330 let srcsz = bx.cx().float_width(ll_t_in);
331 let dstsz = bx.cx().float_width(ll_t_out);
333 bx.fpext(llval, ll_t_out)
334 } else if srcsz > dstsz {
335 bx.fptrunc(llval, ll_t_out)
340 (CastTy::Int(i), CastTy::Float) => {
342 bx.sitofp(llval, ll_t_out)
344 bx.uitofp(llval, ll_t_out)
347 (CastTy::Ptr(_) | CastTy::FnPtr, CastTy::Ptr(_)) => {
348 bx.pointercast(llval, ll_t_out)
350 (CastTy::Int(i), CastTy::Ptr(_)) => {
352 bx.intcast(llval, bx.cx().type_isize(), i.is_signed());
353 bx.inttoptr(usize_llval, ll_t_out)
355 (CastTy::Float, CastTy::Int(IntTy::I)) => {
356 bx.cast_float_to_int(true, llval, ll_t_out)
358 (CastTy::Float, CastTy::Int(_)) => {
359 bx.cast_float_to_int(false, llval, ll_t_out)
361 _ => bug!("unsupported cast: {:?} to {:?}", operand.layout.ty, cast.ty),
363 OperandValue::Immediate(newval)
366 (bx, OperandRef { val, layout: cast })
369 mir::Rvalue::Ref(_, bk, place) => {
370 let mk_ref = move |tcx: TyCtxt<'tcx>, ty: Ty<'tcx>| {
372 tcx.lifetimes.re_erased,
373 ty::TypeAndMut { ty, mutbl: bk.to_mutbl_lossy() },
376 self.codegen_place_to_pointer(bx, place, mk_ref)
379 mir::Rvalue::CopyForDeref(place) => {
380 let operand = self.codegen_operand(&mut bx, &Operand::Copy(place));
383 mir::Rvalue::AddressOf(mutability, place) => {
384 let mk_ptr = move |tcx: TyCtxt<'tcx>, ty: Ty<'tcx>| {
385 tcx.mk_ptr(ty::TypeAndMut { ty, mutbl: mutability })
387 self.codegen_place_to_pointer(bx, place, mk_ptr)
390 mir::Rvalue::Len(place) => {
391 let size = self.evaluate_array_len(&mut bx, place);
392 let operand = OperandRef {
393 val: OperandValue::Immediate(size),
394 layout: bx.cx().layout_of(bx.tcx().types.usize),
399 mir::Rvalue::BinaryOp(op, box (ref lhs, ref rhs)) => {
400 let lhs = self.codegen_operand(&mut bx, lhs);
401 let rhs = self.codegen_operand(&mut bx, rhs);
402 let llresult = match (lhs.val, rhs.val) {
404 OperandValue::Pair(lhs_addr, lhs_extra),
405 OperandValue::Pair(rhs_addr, rhs_extra),
406 ) => self.codegen_fat_ptr_binop(
416 (OperandValue::Immediate(lhs_val), OperandValue::Immediate(rhs_val)) => {
417 self.codegen_scalar_binop(&mut bx, op, lhs_val, rhs_val, lhs.layout.ty)
422 let operand = OperandRef {
423 val: OperandValue::Immediate(llresult),
424 layout: bx.cx().layout_of(op.ty(bx.tcx(), lhs.layout.ty, rhs.layout.ty)),
428 mir::Rvalue::CheckedBinaryOp(op, box (ref lhs, ref rhs)) => {
429 let lhs = self.codegen_operand(&mut bx, lhs);
430 let rhs = self.codegen_operand(&mut bx, rhs);
431 let result = self.codegen_scalar_checked_binop(
438 let val_ty = op.ty(bx.tcx(), lhs.layout.ty, rhs.layout.ty);
439 let operand_ty = bx.tcx().intern_tup(&[val_ty, bx.tcx().types.bool]);
440 let operand = OperandRef { val: result, layout: bx.cx().layout_of(operand_ty) };
445 mir::Rvalue::UnaryOp(op, ref operand) => {
446 let operand = self.codegen_operand(&mut bx, operand);
447 let lloperand = operand.immediate();
448 let is_float = operand.layout.ty.is_floating_point();
449 let llval = match op {
450 mir::UnOp::Not => bx.not(lloperand),
459 (bx, OperandRef { val: OperandValue::Immediate(llval), layout: operand.layout })
462 mir::Rvalue::Discriminant(ref place) => {
463 let discr_ty = rvalue.ty(self.mir, bx.tcx());
464 let discr_ty = self.monomorphize(discr_ty);
466 .codegen_place(&mut bx, place.as_ref())
467 .codegen_get_discr(&mut bx, discr_ty);
471 val: OperandValue::Immediate(discr),
472 layout: self.cx.layout_of(discr_ty),
477 mir::Rvalue::NullaryOp(null_op, ty) => {
478 let ty = self.monomorphize(ty);
479 assert!(bx.cx().type_is_sized(ty));
480 let layout = bx.cx().layout_of(ty);
481 let val = match null_op {
482 mir::NullOp::SizeOf => layout.size.bytes(),
483 mir::NullOp::AlignOf => layout.align.abi.bytes(),
485 let val = bx.cx().const_usize(val);
486 let tcx = self.cx.tcx();
490 val: OperandValue::Immediate(val),
491 layout: self.cx.layout_of(tcx.types.usize),
496 mir::Rvalue::ThreadLocalRef(def_id) => {
497 assert!(bx.cx().tcx().is_static(def_id));
498 let static_ = bx.get_static(def_id);
499 let layout = bx.layout_of(bx.cx().tcx().static_ptr_ty(def_id));
500 let operand = OperandRef::from_immediate_or_packed_pair(&mut bx, static_, layout);
503 mir::Rvalue::Use(ref operand) => {
504 let operand = self.codegen_operand(&mut bx, operand);
507 mir::Rvalue::Repeat(..) | mir::Rvalue::Aggregate(..) => {
508 // According to `rvalue_creates_operand`, only ZST
509 // aggregate rvalues are allowed to be operands.
510 let ty = rvalue.ty(self.mir, self.cx.tcx());
512 OperandRef::new_zst(&mut bx, self.cx.layout_of(self.monomorphize(ty)));
515 mir::Rvalue::ShallowInitBox(ref operand, content_ty) => {
516 let operand = self.codegen_operand(&mut bx, operand);
517 let lloperand = operand.immediate();
519 let content_ty = self.monomorphize(content_ty);
520 let box_layout = bx.cx().layout_of(bx.tcx().mk_box(content_ty));
521 let llty_ptr = bx.cx().backend_type(box_layout);
523 let val = bx.pointercast(lloperand, llty_ptr);
524 let operand = OperandRef { val: OperandValue::Immediate(val), layout: box_layout };
530 fn evaluate_array_len(&mut self, bx: &mut Bx, place: mir::Place<'tcx>) -> Bx::Value {
531 // ZST are passed as operands and require special handling
532 // because codegen_place() panics if Local is operand.
533 if let Some(index) = place.as_local() {
534 if let LocalRef::Operand(Some(op)) = self.locals[index] {
535 if let ty::Array(_, n) = op.layout.ty.kind() {
536 let n = n.eval_usize(bx.cx().tcx(), ty::ParamEnv::reveal_all());
537 return bx.cx().const_usize(n);
541 // use common size calculation for non zero-sized types
542 let cg_value = self.codegen_place(bx, place.as_ref());
543 cg_value.len(bx.cx())
546 /// Codegen an `Rvalue::AddressOf` or `Rvalue::Ref`
547 fn codegen_place_to_pointer(
550 place: mir::Place<'tcx>,
551 mk_ptr_ty: impl FnOnce(TyCtxt<'tcx>, Ty<'tcx>) -> Ty<'tcx>,
552 ) -> (Bx, OperandRef<'tcx, Bx::Value>) {
553 let cg_place = self.codegen_place(&mut bx, place.as_ref());
555 let ty = cg_place.layout.ty;
557 // Note: places are indirect, so storing the `llval` into the
558 // destination effectively creates a reference.
559 let val = if !bx.cx().type_has_metadata(ty) {
560 OperandValue::Immediate(cg_place.llval)
562 OperandValue::Pair(cg_place.llval, cg_place.llextra.unwrap())
564 (bx, OperandRef { val, layout: self.cx.layout_of(mk_ptr_ty(self.cx.tcx(), ty)) })
567 pub fn codegen_scalar_binop(
575 let is_float = input_ty.is_floating_point();
576 let is_signed = input_ty.is_signed();
602 } else if is_signed {
611 } else if is_signed {
617 mir::BinOp::BitOr => bx.or(lhs, rhs),
618 mir::BinOp::BitAnd => bx.and(lhs, rhs),
619 mir::BinOp::BitXor => bx.xor(lhs, rhs),
620 mir::BinOp::Offset => {
621 let pointee_type = input_ty
623 .unwrap_or_else(|| bug!("deref of non-pointer {:?}", input_ty))
625 let llty = bx.cx().backend_type(bx.cx().layout_of(pointee_type));
626 bx.inbounds_gep(llty, lhs, &[rhs])
628 mir::BinOp::Shl => common::build_unchecked_lshift(bx, lhs, rhs),
629 mir::BinOp::Shr => common::build_unchecked_rshift(bx, input_ty, lhs, rhs),
635 | mir::BinOp::Ge => {
637 bx.fcmp(base::bin_op_to_fcmp_predicate(op.to_hir_binop()), lhs, rhs)
639 bx.icmp(base::bin_op_to_icmp_predicate(op.to_hir_binop(), is_signed), lhs, rhs)
645 pub fn codegen_fat_ptr_binop(
650 lhs_extra: Bx::Value,
652 rhs_extra: Bx::Value,
657 let lhs = bx.icmp(IntPredicate::IntEQ, lhs_addr, rhs_addr);
658 let rhs = bx.icmp(IntPredicate::IntEQ, lhs_extra, rhs_extra);
662 let lhs = bx.icmp(IntPredicate::IntNE, lhs_addr, rhs_addr);
663 let rhs = bx.icmp(IntPredicate::IntNE, lhs_extra, rhs_extra);
666 mir::BinOp::Le | mir::BinOp::Lt | mir::BinOp::Ge | mir::BinOp::Gt => {
667 // a OP b ~ a.0 STRICT(OP) b.0 | (a.0 == b.0 && a.1 OP a.1)
668 let (op, strict_op) = match op {
669 mir::BinOp::Lt => (IntPredicate::IntULT, IntPredicate::IntULT),
670 mir::BinOp::Le => (IntPredicate::IntULE, IntPredicate::IntULT),
671 mir::BinOp::Gt => (IntPredicate::IntUGT, IntPredicate::IntUGT),
672 mir::BinOp::Ge => (IntPredicate::IntUGE, IntPredicate::IntUGT),
675 let lhs = bx.icmp(strict_op, lhs_addr, rhs_addr);
676 let and_lhs = bx.icmp(IntPredicate::IntEQ, lhs_addr, rhs_addr);
677 let and_rhs = bx.icmp(op, lhs_extra, rhs_extra);
678 let rhs = bx.and(and_lhs, and_rhs);
682 bug!("unexpected fat ptr binop");
687 pub fn codegen_scalar_checked_binop(
694 ) -> OperandValue<Bx::Value> {
695 // This case can currently arise only from functions marked
696 // with #[rustc_inherit_overflow_checks] and inlined from
697 // another crate (mostly core::num generic/#[inline] fns),
698 // while the current crate doesn't use overflow checks.
699 if !bx.cx().check_overflow() {
700 let val = self.codegen_scalar_binop(bx, op, lhs, rhs, input_ty);
701 return OperandValue::Pair(val, bx.cx().const_bool(false));
704 let (val, of) = match op {
705 // These are checked using intrinsics
706 mir::BinOp::Add | mir::BinOp::Sub | mir::BinOp::Mul => {
708 mir::BinOp::Add => OverflowOp::Add,
709 mir::BinOp::Sub => OverflowOp::Sub,
710 mir::BinOp::Mul => OverflowOp::Mul,
713 bx.checked_binop(oop, input_ty, lhs, rhs)
715 mir::BinOp::Shl | mir::BinOp::Shr => {
716 let lhs_llty = bx.cx().val_ty(lhs);
717 let rhs_llty = bx.cx().val_ty(rhs);
718 let invert_mask = common::shift_mask_val(bx, lhs_llty, rhs_llty, true);
719 let outer_bits = bx.and(rhs, invert_mask);
721 let of = bx.icmp(IntPredicate::IntNE, outer_bits, bx.cx().const_null(rhs_llty));
722 let val = self.codegen_scalar_binop(bx, op, lhs, rhs, input_ty);
726 _ => bug!("Operator `{:?}` is not a checkable operator", op),
729 OperandValue::Pair(val, of)
733 impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
734 pub fn rvalue_creates_operand(&self, rvalue: &mir::Rvalue<'tcx>, span: Span) -> bool {
736 mir::Rvalue::Ref(..) |
737 mir::Rvalue::CopyForDeref(..) |
738 mir::Rvalue::AddressOf(..) |
739 mir::Rvalue::Len(..) |
740 mir::Rvalue::Cast(..) | // (*)
741 mir::Rvalue::ShallowInitBox(..) | // (*)
742 mir::Rvalue::BinaryOp(..) |
743 mir::Rvalue::CheckedBinaryOp(..) |
744 mir::Rvalue::UnaryOp(..) |
745 mir::Rvalue::Discriminant(..) |
746 mir::Rvalue::NullaryOp(..) |
747 mir::Rvalue::ThreadLocalRef(_) |
748 mir::Rvalue::Use(..) => // (*)
750 mir::Rvalue::Repeat(..) |
751 mir::Rvalue::Aggregate(..) => {
752 let ty = rvalue.ty(self.mir, self.cx.tcx());
753 let ty = self.monomorphize(ty);
754 self.cx.spanned_layout_of(ty, span).is_zst()
758 // (*) this is only true if the type is suitable