rustc_codegen_ssa/mir/
statement.rs

1use rustc_middle::mir::{self, NonDivergingIntrinsic};
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.set_debug_loc(bx, statement.source_info);
12        match statement.kind {
13            mir::StatementKind::Assign(box (ref place, ref rvalue)) => {
14                if let Some(index) = place.as_local() {
15                    match self.locals[index] {
16                        LocalRef::Place(cg_dest) => self.codegen_rvalue(bx, cg_dest, rvalue),
17                        LocalRef::UnsizedPlace(cg_indirect_dest) => {
18                            let ty = cg_indirect_dest.layout.ty;
19                            span_bug!(
20                                statement.source_info.span,
21                                "cannot reallocate from `UnsizedPlace({ty})` \
22                                into `{rvalue:?}`; dynamic alloca is not supported",
23                            );
24                        }
25                        LocalRef::PendingOperand => {
26                            let operand = self.codegen_rvalue_operand(bx, rvalue);
27                            self.overwrite_local(index, LocalRef::Operand(operand));
28                            self.debug_introduce_local(bx, index);
29                        }
30                        LocalRef::Operand(op) => {
31                            if !op.layout.is_zst() {
32                                span_bug!(
33                                    statement.source_info.span,
34                                    "operand {:?} already assigned",
35                                    rvalue
36                                );
37                            }
38
39                            // If the type is zero-sized, it's already been set here,
40                            // but we still need to make sure we codegen the operand
41                            self.codegen_rvalue_operand(bx, rvalue);
42                        }
43                    }
44                } else {
45                    let cg_dest = self.codegen_place(bx, place.as_ref());
46                    self.codegen_rvalue(bx, cg_dest, rvalue);
47                }
48            }
49            mir::StatementKind::SetDiscriminant { box ref place, variant_index } => {
50                self.codegen_place(bx, place.as_ref()).codegen_set_discr(bx, variant_index);
51            }
52            mir::StatementKind::Deinit(..) => {
53                // For now, don't codegen this to anything. In the future it may be worth
54                // experimenting with what kind of information we can emit to LLVM without hurting
55                // perf here
56            }
57            mir::StatementKind::StorageLive(local) => {
58                if let LocalRef::Place(cg_place) = self.locals[local] {
59                    cg_place.storage_live(bx);
60                } else if let LocalRef::UnsizedPlace(cg_indirect_place) = self.locals[local] {
61                    cg_indirect_place.storage_live(bx);
62                }
63            }
64            mir::StatementKind::StorageDead(local) => {
65                if let LocalRef::Place(cg_place) = self.locals[local] {
66                    cg_place.storage_dead(bx);
67                } else if let LocalRef::UnsizedPlace(cg_indirect_place) = self.locals[local] {
68                    cg_indirect_place.storage_dead(bx);
69                }
70            }
71            mir::StatementKind::Coverage(ref kind) => {
72                self.codegen_coverage(bx, kind, statement.source_info.scope);
73            }
74            mir::StatementKind::Intrinsic(box NonDivergingIntrinsic::Assume(ref op)) => {
75                let op_val = self.codegen_operand(bx, op);
76                bx.assume(op_val.immediate());
77            }
78            mir::StatementKind::Intrinsic(box NonDivergingIntrinsic::CopyNonOverlapping(
79                mir::CopyNonOverlapping { ref count, ref src, ref dst },
80            )) => {
81                let dst_val = self.codegen_operand(bx, dst);
82                let src_val = self.codegen_operand(bx, src);
83                let count = self.codegen_operand(bx, count).immediate();
84                let pointee_layout = dst_val
85                    .layout
86                    .pointee_info_at(bx, rustc_abi::Size::ZERO)
87                    .expect("Expected pointer");
88                let bytes = bx.mul(count, bx.const_usize(pointee_layout.size.bytes()));
89
90                let align = pointee_layout.align;
91                let dst = dst_val.immediate();
92                let src = src_val.immediate();
93                bx.memcpy(dst, align, src, align, bytes, crate::MemFlags::empty());
94            }
95            mir::StatementKind::FakeRead(..)
96            | mir::StatementKind::Retag { .. }
97            | mir::StatementKind::AscribeUserType(..)
98            | mir::StatementKind::ConstEvalCounter
99            | mir::StatementKind::PlaceMention(..)
100            | mir::StatementKind::BackwardIncompatibleDropHint { .. }
101            | mir::StatementKind::Nop => {}
102        }
103    }
104}
rustc_codegen_ssa/mir/statement.rs

rustc_codegen_ssa/mir/
statement.rs
