3 use rustc_middle::mir::coverage::*;
4 use rustc_middle::mir::{self, Body, Coverage, CoverageInfo};
5 use rustc_middle::ty::query::Providers;
6 use rustc_middle::ty::{self, TyCtxt};
7 use rustc_span::def_id::DefId;
9 /// A `query` provider for retrieving coverage information injected into MIR.
10 pub(crate) fn provide(providers: &mut Providers) {
11 providers.coverageinfo = |tcx, def_id| coverageinfo(tcx, def_id);
12 providers.covered_code_regions = |tcx, def_id| covered_code_regions(tcx, def_id);
15 /// The `num_counters` argument to `llvm.instrprof.increment` is the max counter_id + 1, or in
16 /// other words, the number of counter value references injected into the MIR (plus 1 for the
17 /// reserved `ZERO` counter, which uses counter ID `0` when included in an expression). Injected
18 /// counters have a counter ID from `1..num_counters-1`.
20 /// `num_expressions` is the number of counter expressions added to the MIR body.
22 /// Both `num_counters` and `num_expressions` are used to initialize new vectors, during backend
23 /// code generate, to lookup counters and expressions by simple u32 indexes.
25 /// MIR optimization may split and duplicate some BasicBlock sequences, or optimize out some code
26 /// including injected counters. (It is OK if some counters are optimized out, but those counters
27 /// are still included in the total `num_counters` or `num_expressions`.) Simply counting the
28 /// calls may not work; but computing the number of counters or expressions by adding `1` to the
29 /// highest ID (for a given instrumented function) is valid.
31 /// This visitor runs twice, first with `add_missing_operands` set to `false`, to find the maximum
32 /// counter ID and maximum expression ID based on their enum variant `id` fields; then, as a
33 /// safeguard, with `add_missing_operands` set to `true`, to find any other counter or expression
34 /// IDs referenced by expression operands, if not already seen.
36 /// Ideally, each operand ID in a MIR `CoverageKind::Expression` will have a separate MIR `Coverage`
37 /// statement for the `Counter` or `Expression` with the referenced ID. but since current or future
38 /// MIR optimizations can theoretically optimize out segments of a MIR, it may not be possible to
39 /// guarantee this, so the second pass ensures the `CoverageInfo` counts include all referenced IDs.
40 struct CoverageVisitor {
42 add_missing_operands: bool,
45 impl CoverageVisitor {
46 /// Updates `num_counters` to the maximum encountered zero-based counter_id plus 1. Note the
47 /// final computed number of counters should be the number of all `CoverageKind::Counter`
48 /// statements in the MIR *plus one* for the implicit `ZERO` counter.
50 fn update_num_counters(&mut self, counter_id: u32) {
51 self.info.num_counters = std::cmp::max(self.info.num_counters, counter_id + 1);
54 /// Computes an expression index for each expression ID, and updates `num_expressions` to the
55 /// maximum encountered index plus 1.
57 fn update_num_expressions(&mut self, expression_id: u32) {
58 let expression_index = u32::MAX - expression_id;
59 self.info.num_expressions = std::cmp::max(self.info.num_expressions, expression_index + 1);
62 fn update_from_expression_operand(&mut self, operand_id: u32) {
63 if operand_id >= self.info.num_counters {
64 let operand_as_expression_index = u32::MAX - operand_id;
65 if operand_as_expression_index >= self.info.num_expressions {
66 // The operand ID is outside the known range of counter IDs and also outside the
67 // known range of expression IDs. In either case, the result of a missing operand
68 // (if and when used in an expression) will be zero, so from a computation
69 // perspective, it doesn't matter whether it is interepretted as a counter or an
72 // However, the `num_counters` and `num_expressions` query results are used to
73 // allocate arrays when generating the coverage map (during codegen), so choose
74 // the type that grows either `num_counters` or `num_expressions` the least.
75 if operand_id - self.info.num_counters
76 < operand_as_expression_index - self.info.num_expressions
78 self.update_num_counters(operand_id)
80 self.update_num_expressions(operand_id)
86 fn visit_body(&mut self, body: &Body<'_>) {
87 for bb_data in body.basic_blocks().iter() {
88 for statement in bb_data.statements.iter() {
89 if let StatementKind::Coverage(box ref coverage) = statement.kind {
90 if is_inlined(body, statement) {
93 self.visit_coverage(coverage);
99 fn visit_coverage(&mut self, coverage: &Coverage) {
100 if self.add_missing_operands {
101 match coverage.kind {
102 CoverageKind::Expression { lhs, rhs, .. } => {
103 self.update_from_expression_operand(u32::from(lhs));
104 self.update_from_expression_operand(u32::from(rhs));
109 match coverage.kind {
110 CoverageKind::Counter { id, .. } => {
111 self.update_num_counters(u32::from(id));
113 CoverageKind::Expression { id, .. } => {
114 self.update_num_expressions(u32::from(id));
122 fn coverageinfo<'tcx>(tcx: TyCtxt<'tcx>, instance_def: ty::InstanceDef<'tcx>) -> CoverageInfo {
123 let mir_body = tcx.instance_mir(instance_def);
125 let mut coverage_visitor = CoverageVisitor {
126 // num_counters always has at least the `ZERO` counter.
127 info: CoverageInfo { num_counters: 1, num_expressions: 0 },
128 add_missing_operands: false,
131 coverage_visitor.visit_body(mir_body);
133 coverage_visitor.add_missing_operands = true;
134 coverage_visitor.visit_body(mir_body);
136 coverage_visitor.info
139 fn covered_code_regions<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> Vec<&'tcx CodeRegion> {
140 let body = mir_body(tcx, def_id);
144 data.statements.iter().filter_map(|statement| match statement.kind {
145 StatementKind::Coverage(box ref coverage) => {
146 if is_inlined(body, statement) {
149 coverage.code_region.as_ref() // may be None
159 fn is_inlined(body: &Body<'_>, statement: &Statement<'_>) -> bool {
160 let scope_data = &body.source_scopes[statement.source_info.scope];
161 scope_data.inlined.is_some() || scope_data.inlined_parent_scope.is_some()
164 /// This function ensures we obtain the correct MIR for the given item irrespective of
165 /// whether that means const mir or runtime mir. For `const fn` this opts for runtime
167 fn mir_body<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> &'tcx mir::Body<'tcx> {
168 let id = ty::WithOptConstParam::unknown(def_id);
169 let def = ty::InstanceDef::Item(id);
170 tcx.instance_mir(def)