bjoernager/rust
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coverage: Store the number of counters/expressions in function coverage info

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Coverage codegen can now allocate arrays based on the number of
counters/expressions originally used by the instrumentor.

The existing query that inspects coverage statements is still used for
determining the number of counters passed to `llvm.instrprof.increment`. If
some high-numbered counters were removed by MIR optimizations, the instrumented
binary can potentially use less memory and disk space at runtime.
This commit is contained in:
Zalathar 2023-09-13 12:15:40 +10:00
parent c479bc7f3b
commit a18c5f3b75
8 changed files with 69 additions and 102 deletions
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2
compiler/rustc_middle/src/mir/coverage.rs
View file

@ -140,4 +140,6 @@ impl Op {
#[derive(TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable, TypeVisitable)]
pub struct FunctionCoverageInfo {
pub function_source_hash: u64,
pub num_counters: usize,
pub num_expressions: usize,
}

24
compiler/rustc_middle/src/mir/query.rs
View file

@ -1,5 +1,6 @@
//! Values computed by queries that use MIR.
use crate::mir;
use crate::ty::{self, OpaqueHiddenType, Ty, TyCtxt};
use rustc_data_structures::fx::FxIndexMap;
use rustc_data_structures::unord::UnordSet;
@ -445,14 +446,19 @@ pub struct DestructuredConstant<'tcx> {
pub fields: &'tcx [(ConstValue<'tcx>, Ty<'tcx>)],
}
/// Coverage information summarized from a MIR if instrumented for source code coverage (see
/// compiler option `-Cinstrument-coverage`). This information is generated by the
/// `InstrumentCoverage` MIR pass and can be retrieved via the `coverageinfo` query.
/// Summarizes coverage IDs inserted by the `InstrumentCoverage` MIR pass
/// (for compiler option `-Cinstrument-coverage`), after MIR optimizations
/// have had a chance to potentially remove some of them.
///
/// Used by the `coverage_ids_info` query.
#[derive(Clone, TyEncodable, TyDecodable, Debug, HashStable)]
pub struct CoverageInfo {
/// The total number of coverage region counters added to the MIR `Body`.
pub num_counters: u32,
/// The total number of coverage region counter expressions added to the MIR `Body`.
pub num_expressions: u32,
pub struct CoverageIdsInfo {
/// Coverage codegen needs to know the highest counter ID that is ever
/// incremented within a function, so that it can set the `num-counters`
/// argument of the `llvm.instrprof.increment` intrinsic.
///
/// This may be less than the highest counter ID emitted by the
/// InstrumentCoverage MIR pass, if the highest-numbered counter increments
/// were removed by MIR optimizations.
pub max_counter_id: mir::coverage::CounterId,
}

9
compiler/rustc_middle/src/query/mod.rs
View file

@ -573,10 +573,11 @@ rustc_queries! {
separate_provide_extern
}
/// Returns coverage summary info for a function, after executing the `InstrumentCoverage`
/// MIR pass (assuming the -Cinstrument-coverage option is enabled).
query coverageinfo(key: ty::InstanceDef<'tcx>) -> &'tcx mir::CoverageInfo {
desc { |tcx| "retrieving coverage info from MIR for `{}`", tcx.def_path_str(key.def_id()) }
/// Summarizes coverage IDs inserted by the `InstrumentCoverage` MIR pass
/// (for compiler option `-Cinstrument-coverage`), after MIR optimizations
/// have had a chance to potentially remove some of them.
query coverage_ids_info(key: ty::InstanceDef<'tcx>) -> &'tcx mir::CoverageIdsInfo {
desc { |tcx| "retrieving coverage IDs info from MIR for `{}`", tcx.def_path_str(key.def_id()) }
arena_cache
}