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coverage: Store BCB node IDs in mappings, and resolve them in codegen

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Even though the coverage graph itself is no longer available during codegen,
its nodes can still be used as opaque IDs.
This commit is contained in:
Zalathar 2025-01-20 22:43:59 +11:00
parent 59588250ad
commit ee7dc06cf1
12 changed files with 91 additions and 103 deletions
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29
compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/covfun.rs
View file

@ -11,7 +11,8 @@ use rustc_codegen_ssa::traits::{
BaseTypeCodegenMethods, ConstCodegenMethods, StaticCodegenMethods,
};
use rustc_middle::mir::coverage::{
CovTerm, CoverageIdsInfo, Expression, FunctionCoverageInfo, Mapping, MappingKind, Op,
BasicCoverageBlock, CovTerm, CoverageIdsInfo, Expression, FunctionCoverageInfo, Mapping,
MappingKind, Op,
};
use rustc_middle::ty::{Instance, TyCtxt};
use rustc_span::Span;
@ -140,7 +141,12 @@ fn fill_region_tables<'tcx>(
for &Mapping { ref kind, span } in &fn_cov_info.mappings {
// If the mapping refers to counters/expressions that were removed by
// MIR opts, replace those occurrences with zero.
let kind = kind.map_terms(|term| if is_zero_term(term) { CovTerm::Zero } else { term });
let counter_for_bcb = |bcb: BasicCoverageBlock| -> ffi::Counter {
let term =
fn_cov_info.term_for_bcb[bcb].expect("every BCB in a mapping was given a term");
let term = if is_zero_term(term) { CovTerm::Zero } else { term };
ffi::Counter::from_term(term)
};
// Convert the `Span` into coordinates that we can pass to LLVM, or
// discard the span if conversion fails. In rare, cases _all_ of a
@ -154,23 +160,22 @@ fn fill_region_tables<'tcx>(
continue;
}
match kind {
MappingKind::Code(term) => {
code_regions
.push(ffi::CodeRegion { cov_span, counter: ffi::Counter::from_term(term) });
match *kind {
MappingKind::Code { bcb } => {
code_regions.push(ffi::CodeRegion { cov_span, counter: counter_for_bcb(bcb) });
}
MappingKind::Branch { true_term, false_term } => {
MappingKind::Branch { true_bcb, false_bcb } => {
branch_regions.push(ffi::BranchRegion {
cov_span,
true_counter: ffi::Counter::from_term(true_term),
false_counter: ffi::Counter::from_term(false_term),
true_counter: counter_for_bcb(true_bcb),
false_counter: counter_for_bcb(false_bcb),
});
}
MappingKind::MCDCBranch { true_term, false_term, mcdc_params } => {
MappingKind::MCDCBranch { true_bcb, false_bcb, mcdc_params } => {
mcdc_branch_regions.push(ffi::MCDCBranchRegion {
cov_span,
true_counter: ffi::Counter::from_term(true_term),
false_counter: ffi::Counter::from_term(false_term),
true_counter: counter_for_bcb(true_bcb),
false_counter: counter_for_bcb(false_bcb),
mcdc_branch_params: ffi::mcdc::BranchParameters::from(mcdc_params),
});
}

51
compiler/rustc_middle/src/mir/coverage.rs
View file

@ -179,34 +179,19 @@ pub struct Expression {
#[derive(TyEncodable, TyDecodable, Hash, HashStable)]
pub enum MappingKind {
/// Associates a normal region of code with a counter/expression/zero.
Code(CovTerm),
Code { bcb: BasicCoverageBlock },
/// Associates a branch region with separate counters for true and false.
Branch { true_term: CovTerm, false_term: CovTerm },
Branch { true_bcb: BasicCoverageBlock, false_bcb: BasicCoverageBlock },
/// Associates a branch region with separate counters for true and false.
MCDCBranch { true_term: CovTerm, false_term: CovTerm, mcdc_params: ConditionInfo },
MCDCBranch {
true_bcb: BasicCoverageBlock,
false_bcb: BasicCoverageBlock,
mcdc_params: ConditionInfo,
},
/// Associates a decision region with a bitmap and number of conditions.
MCDCDecision(DecisionInfo),
}
impl MappingKind {
/// Returns a copy of this mapping kind, in which all coverage terms have
/// been replaced with ones returned by the given function.
pub fn map_terms(&self, map_fn: impl Fn(CovTerm) -> CovTerm) -> Self {
match *self {
Self::Code(term) => Self::Code(map_fn(term)),
Self::Branch { true_term, false_term } => {
Self::Branch { true_term: map_fn(true_term), false_term: map_fn(false_term) }
}
Self::MCDCBranch { true_term, false_term, mcdc_params } => Self::MCDCBranch {
true_term: map_fn(true_term),
false_term: map_fn(false_term),
mcdc_params,
},
Self::MCDCDecision(param) => Self::MCDCDecision(param),
}
}
}
#[derive(Clone, Debug)]
#[derive(TyEncodable, TyDecodable, Hash, HashStable)]
pub struct Mapping {
@ -222,10 +207,14 @@ pub struct Mapping {
pub struct FunctionCoverageInfo {
pub function_source_hash: u64,
pub body_span: Span,
pub num_counters: usize,
pub mcdc_bitmap_bits: usize,
pub expressions: IndexVec<ExpressionId, Expression>,
pub mappings: Vec<Mapping>,
pub term_for_bcb: IndexVec<BasicCoverageBlock, Option<CovTerm>>,
pub mcdc_bitmap_bits: usize,
/// The depth of the deepest decision is used to know how many
/// temp condbitmaps should be allocated for the function.
pub mcdc_num_condition_bitmaps: usize,
@ -329,3 +318,19 @@ impl CoverageIdsInfo {
}
}
}
rustc_index::newtype_index! {
/// During the `InstrumentCoverage` MIR pass, a BCB is a node in the
/// "coverage graph", which is a refinement of the MIR control-flow graph
/// that merges or omits some blocks that aren't relevant to coverage.
///
/// After that pass is complete, the coverage graph no longer exists, so a
/// BCB is effectively an opaque ID.
#[derive(HashStable)]
#[encodable]
#[orderable]
#[debug_format = "bcb{}"]
pub struct BasicCoverageBlock {
const START_BCB = 0;
}
}

6
compiler/rustc_mir_transform/src/coverage/counters.rs
View file

@ -133,7 +133,7 @@ pub(super) struct CoverageCounters {
next_counter_id: CounterId,
/// Coverage counters/expressions that are associated with individual BCBs.
node_counters: IndexVec<BasicCoverageBlock, Option<CovTerm>>,
pub(crate) node_counters: IndexVec<BasicCoverageBlock, Option<CovTerm>>,
/// Table of expression data, associating each expression ID with its
/// corresponding operator (+ or -) and its LHS/RHS operands.
@ -203,10 +203,6 @@ impl CoverageCounters {
counter
}
pub(super) fn term_for_bcb(&self, bcb: BasicCoverageBlock) -> Option<CovTerm> {
self.node_counters[bcb]
}
/// Returns an iterator over all the nodes in the coverage graph that
/// should have a counter-increment statement injected into MIR, along with
/// each site's corresponding counter ID.

10
compiler/rustc_mir_transform/src/coverage/graph.rs
View file

@ -8,6 +8,7 @@ use rustc_data_structures::graph::dominators::Dominators;
use rustc_data_structures::graph::{self, DirectedGraph, StartNode};
use rustc_index::IndexVec;
use rustc_index::bit_set::DenseBitSet;
pub(crate) use rustc_middle::mir::coverage::{BasicCoverageBlock, START_BCB};
use rustc_middle::mir::{self, BasicBlock, Terminator, TerminatorKind};
use tracing::debug;
@ -269,15 +270,6 @@ impl graph::Predecessors for CoverageGraph {
}
}
rustc_index::newtype_index! {
/// A node in the control-flow graph of CoverageGraph.
#[orderable]
#[debug_format = "bcb{}"]
pub(crate) struct BasicCoverageBlock {
const START_BCB = 0;
}
}
/// `BasicCoverageBlockData` holds the data indexed by a `BasicCoverageBlock`.
///
/// A `BasicCoverageBlock` (BCB) represents the maximal-length sequence of MIR `BasicBlock`s without

46
compiler/rustc_mir_transform/src/coverage/mod.rs
View file

@ -95,12 +95,13 @@ fn instrument_function_for_coverage<'tcx>(tcx: TyCtxt<'tcx>, mir_body: &mut mir:
let coverage_counters = counters::make_bcb_counters(&graph, &bcbs_with_counter_mappings);
let mappings = create_mappings(&extracted_mappings, &coverage_counters);
let mappings = create_mappings(&extracted_mappings);
if mappings.is_empty() {
// No spans could be converted into valid mappings, so skip this function.
debug!("no spans could be converted into valid mappings; skipping");
return;
}
let term_for_bcb = coverage_counters.node_counters.clone();
inject_coverage_statements(mir_body, &graph, &extracted_mappings, &coverage_counters);
@ -116,26 +117,24 @@ fn instrument_function_for_coverage<'tcx>(tcx: TyCtxt<'tcx>, mir_body: &mut mir:
mir_body.function_coverage_info = Some(Box::new(FunctionCoverageInfo {
function_source_hash: hir_info.function_source_hash,
body_span: hir_info.body_span,
num_counters: coverage_counters.num_counters(),
mcdc_bitmap_bits: extracted_mappings.mcdc_bitmap_bits,
expressions: coverage_counters.into_expressions(),
mappings,
term_for_bcb,
mcdc_bitmap_bits: extracted_mappings.mcdc_bitmap_bits,
mcdc_num_condition_bitmaps,
}));
}
/// For each coverage span extracted from MIR, create a corresponding
/// mapping.
/// For each coverage span extracted from MIR, create a corresponding mapping.
///
/// Precondition: All BCBs corresponding to those spans have been given
/// coverage counters.
fn create_mappings(
extracted_mappings: &ExtractedMappings,
coverage_counters: &CoverageCounters,
) -> Vec<Mapping> {
let term_for_bcb =
|bcb| coverage_counters.term_for_bcb(bcb).expect("all BCBs with spans were given counters");
/// FIXME(Zalathar): This used to be where BCBs in the extracted mappings were
/// resolved to a `CovTerm`. But that is now handled elsewhere, so this
/// function can potentially be simplified even further.
fn create_mappings(extracted_mappings: &ExtractedMappings) -> Vec<Mapping> {
// Fully destructure the mappings struct to make sure we don't miss any kinds.
let ExtractedMappings {
num_bcbs: _,
@ -150,23 +149,18 @@ fn create_mappings(
mappings.extend(code_mappings.iter().map(
// Ordinary code mappings are the simplest kind.
|&mappings::CodeMapping { span, bcb }| {
let kind = MappingKind::Code(term_for_bcb(bcb));
let kind = MappingKind::Code { bcb };
Mapping { kind, span }
},
));
mappings.extend(branch_pairs.iter().map(
|&mappings::BranchPair { span, true_bcb, false_bcb }| {
let true_term = term_for_bcb(true_bcb);
let false_term = term_for_bcb(false_bcb);
let kind = MappingKind::Branch { true_term, false_term };
let kind = MappingKind::Branch { true_bcb, false_bcb };
Mapping { kind, span }
},
));
let term_for_bcb =
|bcb| coverage_counters.term_for_bcb(bcb).expect("all BCBs with spans were given counters");
// MCDC branch mappings are appended with their decisions in case decisions were ignored.
mappings.extend(mcdc_degraded_branches.iter().map(
|&mappings::MCDCBranch {
@ -176,11 +170,7 @@ fn create_mappings(
condition_info: _,
true_index: _,
false_index: _,
}| {
let true_term = term_for_bcb(true_bcb);
let false_term = term_for_bcb(false_bcb);
Mapping { kind: MappingKind::Branch { true_term, false_term }, span }
},
}| { Mapping { kind: MappingKind::Branch { true_bcb, false_bcb }, span } },
));
for (decision, branches) in mcdc_mappings {
@ -201,12 +191,10 @@ fn create_mappings(
true_index: _,
false_index: _,
}| {
let true_term = term_for_bcb(true_bcb);
let false_term = term_for_bcb(false_bcb);
Mapping {
kind: MappingKind::MCDCBranch {
true_term,
false_term,
true_bcb,
false_bcb,
mcdc_params: condition_info,
},
span,

4
compiler/rustc_mir_transform/src/coverage/query.rs
View file

@ -101,7 +101,9 @@ fn coverage_ids_info<'tcx>(
// to any particular point in the control-flow graph.
// (Keep this in sync with the injection of `ExpressionUsed`
// statements in the `InstrumentCoverage` MIR pass.)
if let MappingKind::Code(CovTerm::Expression(id)) = mapping.kind {
if let MappingKind::Code { bcb } = mapping.kind
&& let Some(CovTerm::Expression(id)) = fn_cov_info.term_for_bcb[bcb]
{
expressions_seen.remove(id);
}
}

12
tests/mir-opt/coverage/branch_match_arms.main.InstrumentCoverage.diff
View file

@ -30,12 +30,12 @@
+ coverage ExpressionId(0) => Expression { lhs: Counter(1), op: Add, rhs: Counter(2) };
+ coverage ExpressionId(1) => Expression { lhs: Expression(0), op: Add, rhs: Counter(3) };
+ coverage ExpressionId(2) => Expression { lhs: Counter(0), op: Subtract, rhs: Expression(1) };
+ coverage Code(Counter(0)) => $DIR/branch_match_arms.rs:14:1: 15:21 (#0);
+ coverage Code(Counter(1)) => $DIR/branch_match_arms.rs:16:17: 16:33 (#0);
+ coverage Code(Counter(2)) => $DIR/branch_match_arms.rs:17:17: 17:33 (#0);
+ coverage Code(Counter(3)) => $DIR/branch_match_arms.rs:18:17: 18:33 (#0);
+ coverage Code(Expression(2)) => $DIR/branch_match_arms.rs:19:17: 19:33 (#0);
+ coverage Code(Counter(0)) => $DIR/branch_match_arms.rs:21:2: 21:2 (#0);
+ coverage Code { bcb: bcb0 } => $DIR/branch_match_arms.rs:14:1: 15:21 (#0);
+ coverage Code { bcb: bcb1 } => $DIR/branch_match_arms.rs:16:17: 16:33 (#0);
+ coverage Code { bcb: bcb3 } => $DIR/branch_match_arms.rs:17:17: 17:33 (#0);
+ coverage Code { bcb: bcb4 } => $DIR/branch_match_arms.rs:18:17: 18:33 (#0);
+ coverage Code { bcb: bcb5 } => $DIR/branch_match_arms.rs:19:17: 19:33 (#0);
+ coverage Code { bcb: bcb2 } => $DIR/branch_match_arms.rs:21:2: 21:2 (#0);
+
bb0: {
+ Coverage::CounterIncrement(0);

2
tests/mir-opt/coverage/instrument_coverage.bar.InstrumentCoverage.diff
View file

@ -5,7 +5,7 @@
let mut _0: bool;
+ coverage body span: $DIR/instrument_coverage.rs:29:18: 31:2 (#0)
+ coverage Code(Counter(0)) => $DIR/instrument_coverage.rs:29:1: 31:2 (#0);
+ coverage Code { bcb: bcb0 } => $DIR/instrument_coverage.rs:29:1: 31:2 (#0);
+
bb0: {
+ Coverage::CounterIncrement(0);

10
tests/mir-opt/coverage/instrument_coverage.main.InstrumentCoverage.diff
View file

@ -9,11 +9,11 @@
+ coverage body span: $DIR/instrument_coverage.rs:14:11: 20:2 (#0)
+ coverage ExpressionId(0) => Expression { lhs: Counter(1), op: Subtract, rhs: Counter(0) };
+ coverage Code(Counter(0)) => $DIR/instrument_coverage.rs:14:1: 14:11 (#0);
+ coverage Code(Counter(1)) => $DIR/instrument_coverage.rs:16:12: 16:17 (#0);
+ coverage Code(Counter(0)) => $DIR/instrument_coverage.rs:17:13: 17:18 (#0);
+ coverage Code(Expression(0)) => $DIR/instrument_coverage.rs:18:10: 18:10 (#0);
+ coverage Code(Counter(0)) => $DIR/instrument_coverage.rs:20:2: 20:2 (#0);
+ coverage Code { bcb: bcb0 } => $DIR/instrument_coverage.rs:14:1: 14:11 (#0);
+ coverage Code { bcb: bcb1 } => $DIR/instrument_coverage.rs:16:12: 16:17 (#0);
+ coverage Code { bcb: bcb2 } => $DIR/instrument_coverage.rs:17:13: 17:18 (#0);
+ coverage Code { bcb: bcb3 } => $DIR/instrument_coverage.rs:18:10: 18:10 (#0);
+ coverage Code { bcb: bcb2 } => $DIR/instrument_coverage.rs:20:2: 20:2 (#0);
+
bb0: {
+ Coverage::CounterIncrement(0);

4
tests/mir-opt/coverage/instrument_coverage.rs
View file

@ -8,7 +8,7 @@
// EMIT_MIR instrument_coverage.main.InstrumentCoverage.diff
// CHECK-LABEL: fn main()
// CHECK: coverage body span:
// CHECK: coverage Code(Counter({{[0-9]+}})) =>
// CHECK: coverage Code { bcb: bcb{{[0-9]+}} } =>
// CHECK: bb0:
// CHECK: Coverage::CounterIncrement
fn main() {
@ -22,7 +22,7 @@ fn main() {
// EMIT_MIR instrument_coverage.bar.InstrumentCoverage.diff
// CHECK-LABEL: fn bar()
// CHECK: coverage body span:
// CHECK: coverage Code(Counter({{[0-9]+}})) =>
// CHECK: coverage Code { bcb: bcb{{[0-9]+}} } =>
// CHECK: bb0:
// CHECK: Coverage::CounterIncrement
#[inline(never)]

10
tests/mir-opt/coverage/instrument_coverage_cleanup.main.CleanupPostBorrowck.diff
View file

@ -9,11 +9,11 @@
coverage body span: $DIR/instrument_coverage_cleanup.rs:13:11: 15:2 (#0)
coverage ExpressionId(0) => Expression { lhs: Counter(0), op: Subtract, rhs: Counter(1) };
coverage Code(Counter(0)) => $DIR/instrument_coverage_cleanup.rs:13:1: 14:36 (#0);
coverage Code(Expression(0)) => $DIR/instrument_coverage_cleanup.rs:14:37: 14:39 (#0);
coverage Code(Counter(1)) => $DIR/instrument_coverage_cleanup.rs:14:39: 14:39 (#0);
coverage Code(Counter(0)) => $DIR/instrument_coverage_cleanup.rs:15:2: 15:2 (#0);
coverage Branch { true_term: Expression(0), false_term: Counter(1) } => $DIR/instrument_coverage_cleanup.rs:14:8: 14:36 (#0);
coverage Code { bcb: bcb0 } => $DIR/instrument_coverage_cleanup.rs:13:1: 14:36 (#0);
coverage Code { bcb: bcb3 } => $DIR/instrument_coverage_cleanup.rs:14:37: 14:39 (#0);
coverage Code { bcb: bcb1 } => $DIR/instrument_coverage_cleanup.rs:14:39: 14:39 (#0);
coverage Code { bcb: bcb2 } => $DIR/instrument_coverage_cleanup.rs:15:2: 15:2 (#0);
coverage Branch { true_bcb: bcb3, false_bcb: bcb1 } => $DIR/instrument_coverage_cleanup.rs:14:8: 14:36 (#0);
bb0: {
Coverage::CounterIncrement(0);

10
tests/mir-opt/coverage/instrument_coverage_cleanup.main.InstrumentCoverage.diff
View file

@ -9,11 +9,11 @@
+ coverage body span: $DIR/instrument_coverage_cleanup.rs:13:11: 15:2 (#0)
+ coverage ExpressionId(0) => Expression { lhs: Counter(0), op: Subtract, rhs: Counter(1) };
+ coverage Code(Counter(0)) => $DIR/instrument_coverage_cleanup.rs:13:1: 14:36 (#0);
+ coverage Code(Expression(0)) => $DIR/instrument_coverage_cleanup.rs:14:37: 14:39 (#0);
+ coverage Code(Counter(1)) => $DIR/instrument_coverage_cleanup.rs:14:39: 14:39 (#0);
+ coverage Code(Counter(0)) => $DIR/instrument_coverage_cleanup.rs:15:2: 15:2 (#0);
+ coverage Branch { true_term: Expression(0), false_term: Counter(1) } => $DIR/instrument_coverage_cleanup.rs:14:8: 14:36 (#0);
+ coverage Code { bcb: bcb0 } => $DIR/instrument_coverage_cleanup.rs:13:1: 14:36 (#0);
+ coverage Code { bcb: bcb3 } => $DIR/instrument_coverage_cleanup.rs:14:37: 14:39 (#0);
+ coverage Code { bcb: bcb1 } => $DIR/instrument_coverage_cleanup.rs:14:39: 14:39 (#0);
+ coverage Code { bcb: bcb2 } => $DIR/instrument_coverage_cleanup.rs:15:2: 15:2 (#0);
+ coverage Branch { true_bcb: bcb3, false_bcb: bcb1 } => $DIR/instrument_coverage_cleanup.rs:14:8: 14:36 (#0);
+
bb0: {
+ Coverage::CounterIncrement(0);