1 //! Lowers intrinsic calls
4 use rustc_middle::mir::*;
5 use rustc_middle::ty::subst::SubstsRef;
6 use rustc_middle::ty::{self, Ty, TyCtxt};
7 use rustc_span::symbol::{sym, Symbol};
10 pub struct LowerIntrinsics;
12 impl<'tcx> MirPass<'tcx> for LowerIntrinsics {
13 fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
14 let local_decls = &body.local_decls;
15 for block in body.basic_blocks.as_mut() {
16 let terminator = block.terminator.as_mut().unwrap();
17 if let TerminatorKind::Call { func, args, destination, target, .. } =
20 let func_ty = func.ty(local_decls, tcx);
21 let Some((intrinsic_name, substs)) = resolve_rust_intrinsic(tcx, func_ty) else {
24 match intrinsic_name {
26 terminator.kind = TerminatorKind::Unreachable;
29 if let Some(target) = *target {
30 block.statements.push(Statement {
31 source_info: terminator.source_info,
32 kind: StatementKind::Assign(Box::new((
34 Rvalue::Use(Operand::Constant(Box::new(Constant {
35 span: terminator.source_info.span,
37 literal: ConstantKind::zero_sized(tcx.types.unit),
41 terminator.kind = TerminatorKind::Goto { target };
44 sym::copy_nonoverlapping => {
45 let target = target.unwrap();
46 let mut args = args.drain(..);
47 block.statements.push(Statement {
48 source_info: terminator.source_info,
49 kind: StatementKind::CopyNonOverlapping(Box::new(
50 rustc_middle::mir::CopyNonOverlapping {
51 src: args.next().unwrap(),
52 dst: args.next().unwrap(),
53 count: args.next().unwrap(),
60 "Extra argument for copy_non_overlapping intrinsic"
63 terminator.kind = TerminatorKind::Goto { target };
65 sym::wrapping_add | sym::wrapping_sub | sym::wrapping_mul => {
66 if let Some(target) = *target {
70 let mut args = args.drain(..);
71 lhs = args.next().unwrap();
72 rhs = args.next().unwrap();
74 let bin_op = match intrinsic_name {
75 sym::wrapping_add => BinOp::Add,
76 sym::wrapping_sub => BinOp::Sub,
77 sym::wrapping_mul => BinOp::Mul,
78 _ => bug!("unexpected intrinsic"),
80 block.statements.push(Statement {
81 source_info: terminator.source_info,
82 kind: StatementKind::Assign(Box::new((
84 Rvalue::BinaryOp(bin_op, Box::new((lhs, rhs))),
87 terminator.kind = TerminatorKind::Goto { target };
90 sym::add_with_overflow | sym::sub_with_overflow | sym::mul_with_overflow => {
91 // The checked binary operations are not suitable target for lowering here,
92 // since their semantics depend on the value of overflow-checks flag used
93 // during codegen. Issue #35310.
95 sym::size_of | sym::min_align_of => {
96 if let Some(target) = *target {
97 let tp_ty = substs.type_at(0);
98 let null_op = match intrinsic_name {
99 sym::size_of => NullOp::SizeOf,
100 sym::min_align_of => NullOp::AlignOf,
101 _ => bug!("unexpected intrinsic"),
103 block.statements.push(Statement {
104 source_info: terminator.source_info,
105 kind: StatementKind::Assign(Box::new((
107 Rvalue::NullaryOp(null_op, tp_ty),
110 terminator.kind = TerminatorKind::Goto { target };
113 sym::discriminant_value => {
114 if let (Some(target), Some(arg)) = (*target, args[0].place()) {
115 let arg = tcx.mk_place_deref(arg);
116 block.statements.push(Statement {
117 source_info: terminator.source_info,
118 kind: StatementKind::Assign(Box::new((
120 Rvalue::Discriminant(arg),
123 terminator.kind = TerminatorKind::Goto { target };
126 _ if intrinsic_name.as_str().starts_with("simd_shuffle") => {
127 validate_simd_shuffle(tcx, args, terminator.source_info.span);
136 fn resolve_rust_intrinsic<'tcx>(
139 ) -> Option<(Symbol, SubstsRef<'tcx>)> {
140 if let ty::FnDef(def_id, substs) = *func_ty.kind() {
141 if tcx.is_intrinsic(def_id) {
142 return Some((tcx.item_name(def_id), substs));
148 fn validate_simd_shuffle<'tcx>(tcx: TyCtxt<'tcx>, args: &[Operand<'tcx>], span: Span) {
150 Operand::Constant(_) => {} // all good
152 let msg = "last argument of `simd_shuffle` is required to be a `const` item";
153 tcx.sess.span_err(span, msg);