1 use crate::transform::{MirPass, MirSource};
2 use crate::util::patch::MirPatch;
3 use rustc_data_structures::fingerprint::Fingerprint;
4 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
5 use rustc_hir::lang_items;
7 use rustc_middle::ich::StableHashingContext;
8 use rustc_middle::mir::coverage::*;
9 use rustc_middle::mir::interpret::Scalar;
10 use rustc_middle::mir::CoverageInfo;
11 use rustc_middle::mir::{
12 self, traversal, BasicBlock, BasicBlockData, Operand, Place, SourceInfo, StatementKind,
13 Terminator, TerminatorKind, START_BLOCK,
16 use rustc_middle::ty::query::Providers;
17 use rustc_middle::ty::FnDef;
18 use rustc_middle::ty::TyCtxt;
19 use rustc_span::def_id::DefId;
20 use rustc_span::{Pos, Span};
22 /// Inserts call to count_code_region() as a placeholder to be replaced during code generation with
23 /// the intrinsic llvm.instrprof.increment.
24 pub struct InstrumentCoverage;
26 /// The `query` provider for `CoverageInfo`, requested by `codegen_intrinsic_call()` when
27 /// constructing the arguments for `llvm.instrprof.increment`.
28 pub(crate) fn provide(providers: &mut Providers<'_>) {
29 providers.coverageinfo = |tcx, def_id| coverageinfo_from_mir(tcx, def_id);
32 fn coverageinfo_from_mir<'tcx>(tcx: TyCtxt<'tcx>, mir_def_id: DefId) -> CoverageInfo {
33 let mir_body = tcx.optimized_mir(mir_def_id);
34 // FIXME(richkadel): The current implementation assumes the MIR for the given DefId
35 // represents a single function. Validate and/or correct if inlining (which should be disabled
36 // if -Zinstrument-coverage is enabled) and/or monomorphization invalidates these assumptions.
37 let count_code_region_fn = tcx.require_lang_item(lang_items::CountCodeRegionFnLangItem, None);
39 // The `num_counters` argument to `llvm.instrprof.increment` is the number of injected
40 // counters, with each counter having an index from `0..num_counters-1`. MIR optimization
41 // may split and duplicate some BasicBlock sequences. Simply counting the calls may not
42 // not work; but computing the num_counters by adding `1` to the highest index (for a given
43 // instrumented function) is valid.
44 let mut num_counters: u32 = 0;
45 for terminator in traversal::preorder(mir_body)
46 .map(|(_, data)| (data, count_code_region_fn))
47 .filter_map(terminators_that_call_given_fn)
49 if let TerminatorKind::Call { args, .. } = &terminator.kind {
50 let index_arg = args.get(count_code_region_args::COUNTER_INDEX).expect("arg found");
52 mir::Operand::scalar_from_const(index_arg).to_u32().expect("index arg is u32");
53 num_counters = std::cmp::max(num_counters, index + 1);
56 let hash = if num_counters > 0 { hash_mir_source(tcx, mir_def_id) } else { 0 };
57 CoverageInfo { num_counters, hash }
60 fn terminators_that_call_given_fn(
61 (data, fn_def_id): (&'tcx BasicBlockData<'tcx>, DefId),
62 ) -> Option<&'tcx Terminator<'tcx>> {
63 if let Some(terminator) = &data.terminator {
64 if let TerminatorKind::Call { func: Operand::Constant(func), .. } = &terminator.kind {
65 if let FnDef(called_fn_def_id, _) = func.literal.ty.kind {
66 if called_fn_def_id == fn_def_id {
67 return Some(&terminator);
75 struct Instrumentor<'tcx> {
80 impl<'tcx> MirPass<'tcx> for InstrumentCoverage {
81 fn run_pass(&self, tcx: TyCtxt<'tcx>, src: MirSource<'tcx>, mir_body: &mut mir::Body<'tcx>) {
82 if tcx.sess.opts.debugging_opts.instrument_coverage {
83 // If the InstrumentCoverage pass is called on promoted MIRs, skip them.
84 // See: https://github.com/rust-lang/rust/pull/73011#discussion_r438317601
85 if src.promoted.is_none() {
87 "instrumenting {:?}, span: {}",
89 tcx.sess.source_map().span_to_string(mir_body.span)
91 Instrumentor::new(tcx).inject_counters(mir_body);
97 impl<'tcx> Instrumentor<'tcx> {
98 fn new(tcx: TyCtxt<'tcx>) -> Self {
99 Self { tcx, num_counters: 0 }
102 fn next_counter(&mut self) -> u32 {
103 let next = self.num_counters;
104 self.num_counters += 1;
108 fn inject_counters(&mut self, mir_body: &mut mir::Body<'tcx>) {
109 // FIXME(richkadel): As a first step, counters are only injected at the top of each
110 // function. The complete solution will inject counters at each conditional code branch.
111 let code_region = mir_body.span;
112 let next_block = START_BLOCK;
113 self.inject_counter(mir_body, code_region, next_block);
118 mir_body: &mut mir::Body<'tcx>,
120 next_block: BasicBlock,
122 let injection_point = code_region.shrink_to_lo();
124 let count_code_region_fn = function_handle(
126 self.tcx.require_lang_item(lang_items::CountCodeRegionFnLangItem, None),
130 let index = self.next_counter();
132 let mut args = Vec::new();
134 use count_code_region_args::*;
135 debug_assert_eq!(COUNTER_INDEX, args.len());
136 args.push(self.const_u32(index, injection_point));
138 debug_assert_eq!(START_BYTE_POS, args.len());
139 args.push(self.const_u32(code_region.lo().to_u32(), injection_point));
141 debug_assert_eq!(END_BYTE_POS, args.len());
142 args.push(self.const_u32(code_region.hi().to_u32(), injection_point));
144 let mut patch = MirPatch::new(mir_body);
146 let temp = patch.new_temp(self.tcx.mk_unit(), code_region);
147 let new_block = patch.new_block(placeholder_block(code_region));
148 patch.patch_terminator(
150 TerminatorKind::Call {
151 func: count_code_region_fn,
153 // new_block will swapped with the next_block, after applying patch
154 destination: Some((Place::from(temp), new_block)),
156 from_hir_call: false,
157 fn_span: injection_point,
161 patch.add_statement(new_block.start_location(), StatementKind::StorageLive(temp));
162 patch.add_statement(next_block.start_location(), StatementKind::StorageDead(temp));
164 patch.apply(mir_body);
166 // To insert the `new_block` in front of the first block in the counted branch (the
167 // `next_block`), just swap the indexes, leaving the rest of the graph unchanged.
168 mir_body.basic_blocks_mut().swap(next_block, new_block);
171 fn const_u32(&self, value: u32, span: Span) -> Operand<'tcx> {
172 Operand::const_from_scalar(self.tcx, self.tcx.types.u32, Scalar::from_u32(value), span)
176 fn function_handle<'tcx>(tcx: TyCtxt<'tcx>, fn_def_id: DefId, span: Span) -> Operand<'tcx> {
177 let ret_ty = tcx.fn_sig(fn_def_id).output();
178 let ret_ty = ret_ty.no_bound_vars().unwrap();
179 let substs = tcx.mk_substs(::std::iter::once(ty::subst::GenericArg::from(ret_ty)));
180 Operand::function_handle(tcx, fn_def_id, substs, span)
183 fn placeholder_block(span: Span) -> BasicBlockData<'tcx> {
186 terminator: Some(Terminator {
187 source_info: SourceInfo::outermost(span),
188 // this gets overwritten by the counter Call
189 kind: TerminatorKind::Unreachable,
195 fn hash_mir_source<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> u64 {
196 let hir_node = tcx.hir().get_if_local(def_id).expect("DefId is local");
197 let fn_body_id = hir::map::associated_body(hir_node).expect("HIR node is a function with body");
198 let hir_body = tcx.hir().body(fn_body_id);
199 let mut hcx = tcx.create_no_span_stable_hashing_context();
200 hash(&mut hcx, &hir_body.value).to_smaller_hash()
204 hcx: &mut StableHashingContext<'tcx>,
205 node: &impl HashStable<StableHashingContext<'tcx>>,
207 let mut stable_hasher = StableHasher::new();
208 node.hash_stable(hcx, &mut stable_hasher);
209 stable_hasher.finish()