rustc_codegen_ssa/mir/
statement.rs

1use rustc_middle::mir::{self, NonDivergingIntrinsic, StmtDebugInfo};
2use rustc_middle::span_bug;
3use tracing::instrument;
4
5use super::{FunctionCx, LocalRef};
6use crate::traits::*;
7
8impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
9    #[instrument(level = "debug", skip(self, bx))]
10    pub(crate) fn codegen_statement(&mut self, bx: &mut Bx, statement: &mir::Statement<'tcx>) {
11        self.codegen_stmt_debuginfos(bx, &statement.debuginfos);
12        self.set_debug_loc(bx, statement.source_info);
13        match statement.kind {
14            mir::StatementKind::Assign(box (ref place, ref rvalue)) => {
15                if let Some(index) = place.as_local() {
16                    match self.locals[index] {
17                        LocalRef::Place(cg_dest) => self.codegen_rvalue(bx, cg_dest, rvalue),
18                        LocalRef::UnsizedPlace(cg_indirect_dest) => {
19                            let ty = cg_indirect_dest.layout.ty;
20                            span_bug!(
21                                statement.source_info.span,
22                                "cannot reallocate from `UnsizedPlace({ty})` \
23                                into `{rvalue:?}`; dynamic alloca is not supported",
24                            );
25                        }
26                        LocalRef::PendingOperand => {
27                            let operand = self.codegen_rvalue_operand(bx, rvalue);
28                            self.overwrite_local(index, LocalRef::Operand(operand));
29                            self.debug_introduce_local(bx, index);
30                        }
31                        LocalRef::Operand(op) => {
32                            if !op.layout.is_zst() {
33                                span_bug!(
34                                    statement.source_info.span,
35                                    "operand {:?} already assigned",
36                                    rvalue
37                                );
38                            }
39
40                            // If the type is zero-sized, it's already been set here,
41                            // but we still need to make sure we codegen the operand
42                            self.codegen_rvalue_operand(bx, rvalue);
43                        }
44                    }
45                } else {
46                    let cg_dest = self.codegen_place(bx, place.as_ref());
47                    self.codegen_rvalue(bx, cg_dest, rvalue);
48                }
49            }
50            mir::StatementKind::SetDiscriminant { box ref place, variant_index } => {
51                self.codegen_place(bx, place.as_ref()).codegen_set_discr(bx, variant_index);
52            }
53            mir::StatementKind::StorageLive(local) => {
54                if let LocalRef::Place(cg_place) = self.locals[local] {
55                    cg_place.storage_live(bx);
56                } else if let LocalRef::UnsizedPlace(cg_indirect_place) = self.locals[local] {
57                    cg_indirect_place.storage_live(bx);
58                }
59            }
60            mir::StatementKind::StorageDead(local) => {
61                if let LocalRef::Place(cg_place) = self.locals[local] {
62                    cg_place.storage_dead(bx);
63                } else if let LocalRef::UnsizedPlace(cg_indirect_place) = self.locals[local] {
64                    cg_indirect_place.storage_dead(bx);
65                }
66            }
67            mir::StatementKind::Coverage(ref kind) => {
68                self.codegen_coverage(bx, kind, statement.source_info.scope);
69            }
70            mir::StatementKind::Intrinsic(box NonDivergingIntrinsic::Assume(ref op)) => {
71                let op_val = self.codegen_operand(bx, op);
72                bx.assume(op_val.immediate());
73            }
74            mir::StatementKind::Intrinsic(box NonDivergingIntrinsic::CopyNonOverlapping(
75                mir::CopyNonOverlapping { ref count, ref src, ref dst },
76            )) => {
77                let dst_val = self.codegen_operand(bx, dst);
78                let src_val = self.codegen_operand(bx, src);
79                let count = self.codegen_operand(bx, count).immediate();
80                let pointee_layout = dst_val
81                    .layout
82                    .pointee_info_at(bx, rustc_abi::Size::ZERO)
83                    .expect("Expected pointer");
84                let bytes = bx.mul(count, bx.const_usize(pointee_layout.size.bytes()));
85
86                let align = pointee_layout.align;
87                let dst = dst_val.immediate();
88                let src = src_val.immediate();
89                bx.memcpy(dst, align, src, align, bytes, crate::MemFlags::empty(), None);
90            }
91            mir::StatementKind::FakeRead(..)
92            | mir::StatementKind::Retag { .. }
93            | mir::StatementKind::AscribeUserType(..)
94            | mir::StatementKind::ConstEvalCounter
95            | mir::StatementKind::PlaceMention(..)
96            | mir::StatementKind::BackwardIncompatibleDropHint { .. }
97            | mir::StatementKind::Nop => {}
98        }
99    }
100
101    pub(crate) fn codegen_stmt_debuginfo(&mut self, bx: &mut Bx, debuginfo: &StmtDebugInfo<'tcx>) {
102        match debuginfo {
103            StmtDebugInfo::AssignRef(dest, place) => {
104                let local_ref = match self.locals[place.local] {
105                    // For an rvalue like `&(_1.1)`, when `BackendRepr` is `BackendRepr::Memory`, we allocate a block of memory to this place.
106                    // The place is an indirect pointer, we can refer to it directly.
107                    LocalRef::Place(place_ref) => Some((place_ref, place.projection.as_slice())),
108                    // For an rvalue like `&((*_1).1)`, we are calculating the address of `_1.1`.
109                    // The deref projection is no-op here.
110                    LocalRef::Operand(operand_ref) if place.is_indirect_first_projection() => {
111                        Some((operand_ref.deref(bx.cx()), &place.projection[1..]))
112                    }
113                    // For an rvalue like `&1`, when `BackendRepr` is `BackendRepr::Scalar`,
114                    // we cannot get the address.
115                    // N.B. `non_ssa_locals` returns that this is an SSA local.
116                    LocalRef::Operand(_) => None,
117                    LocalRef::UnsizedPlace(_) | LocalRef::PendingOperand => None,
118                }
119                .filter(|(_, projection)| {
120                    // Drop unsupported projections.
121                    projection.iter().all(|p| p.can_use_in_debuginfo())
122                });
123                if let Some((base, projection)) = local_ref {
124                    self.debug_new_val_to_local(bx, *dest, base, projection);
125                } else {
126                    // If the address cannot be calculated, use poison to indicate that the value has been optimized out.
127                    self.debug_poison_to_local(bx, *dest);
128                }
129            }
130            StmtDebugInfo::InvalidAssign(local) => {
131                self.debug_poison_to_local(bx, *local);
132            }
133        }
134    }
135
136    pub(crate) fn codegen_stmt_debuginfos(
137        &mut self,
138        bx: &mut Bx,
139        debuginfos: &[StmtDebugInfo<'tcx>],
140    ) {
141        for debuginfo in debuginfos {
142            self.codegen_stmt_debuginfo(bx, debuginfo);
143        }
144    }
145}
rustc_codegen_ssa/mir/statement.rs

rustc_codegen_ssa/mir/
statement.rs
