diff options
Diffstat (limited to 'compiler/rustc_mir_transform/src/coverage/query.rs')
| -rw-r--r-- | compiler/rustc_mir_transform/src/coverage/query.rs | 167 |
1 files changed, 47 insertions, 120 deletions
diff --git a/compiler/rustc_mir_transform/src/coverage/query.rs b/compiler/rustc_mir_transform/src/coverage/query.rs index a849ed4c3e2..cd89fbe772d 100644 --- a/compiler/rustc_mir_transform/src/coverage/query.rs +++ b/compiler/rustc_mir_transform/src/coverage/query.rs @@ -1,10 +1,7 @@ use rustc_data_structures::captures::Captures; use rustc_index::bit_set::DenseBitSet; use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags; -use rustc_middle::mir::coverage::{ - CounterId, CovTerm, CoverageIdsInfo, CoverageKind, Expression, ExpressionId, - FunctionCoverageInfo, MappingKind, Op, -}; +use rustc_middle::mir::coverage::{BasicCoverageBlock, CoverageIdsInfo, CoverageKind, MappingKind}; use rustc_middle::mir::{Body, Statement, StatementKind}; use rustc_middle::ty::{self, TyCtxt}; use rustc_middle::util::Providers; @@ -12,6 +9,9 @@ use rustc_span::def_id::LocalDefId; use rustc_span::sym; use tracing::trace; +use crate::coverage::counters::node_flow::make_node_counters; +use crate::coverage::counters::{CoverageCounters, transcribe_counters}; + /// Registers query/hook implementations related to coverage. pub(crate) fn provide(providers: &mut Providers) { providers.hooks.is_eligible_for_coverage = is_eligible_for_coverage; @@ -89,39 +89,57 @@ fn coverage_ids_info<'tcx>( let mir_body = tcx.instance_mir(instance_def); let fn_cov_info = mir_body.function_coverage_info.as_deref()?; - let mut counters_seen = DenseBitSet::new_empty(fn_cov_info.num_counters); - let mut expressions_seen = DenseBitSet::new_filled(fn_cov_info.expressions.len()); - - // For each expression ID that is directly used by one or more mappings, - // mark it as not-yet-seen. This indicates that we expect to see a - // corresponding `ExpressionUsed` statement during MIR traversal. - for mapping in fn_cov_info.mappings.iter() { - // Currently we only worry about ordinary code mappings. - // For branch and MC/DC mappings, expressions might not correspond - // 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 { - expressions_seen.remove(id); - } - } - + // Scan through the final MIR to see which BCBs survived MIR opts. + // Any BCB not in this set was optimized away. + let mut bcbs_seen = DenseBitSet::new_empty(fn_cov_info.priority_list.len()); for kind in all_coverage_in_mir_body(mir_body) { match *kind { - CoverageKind::CounterIncrement { id } => { - counters_seen.insert(id); - } - CoverageKind::ExpressionUsed { id } => { - expressions_seen.insert(id); + CoverageKind::VirtualCounter { bcb } => { + bcbs_seen.insert(bcb); } _ => {} } } - let zero_expressions = - identify_zero_expressions(fn_cov_info, &counters_seen, &expressions_seen); + // Determine the set of BCBs that are referred to by mappings, and therefore + // need a counter. Any node not in this set will only get a counter if it + // is part of the counter expression for a node that is in the set. + let mut bcb_needs_counter = + DenseBitSet::<BasicCoverageBlock>::new_empty(fn_cov_info.priority_list.len()); + for mapping in &fn_cov_info.mappings { + match mapping.kind { + MappingKind::Code { bcb } => { + bcb_needs_counter.insert(bcb); + } + MappingKind::Branch { true_bcb, false_bcb } => { + bcb_needs_counter.insert(true_bcb); + bcb_needs_counter.insert(false_bcb); + } + MappingKind::MCDCBranch { true_bcb, false_bcb, mcdc_params: _ } => { + bcb_needs_counter.insert(true_bcb); + bcb_needs_counter.insert(false_bcb); + } + MappingKind::MCDCDecision(_) => {} + } + } - Some(CoverageIdsInfo { counters_seen, zero_expressions }) + // FIXME(Zalathar): It should be possible to sort `priority_list[1..]` by + // `!bcbs_seen.contains(bcb)` to simplify the mappings even further, at the + // expense of some churn in the tests. When doing so, also consider removing + // the sorts in `transcribe_counters`. + let node_counters = make_node_counters(&fn_cov_info.node_flow_data, &fn_cov_info.priority_list); + let coverage_counters = transcribe_counters(&node_counters, &bcb_needs_counter, &bcbs_seen); + + let CoverageCounters { + phys_counter_for_node, next_counter_id, node_counters, expressions, .. + } = coverage_counters; + + Some(CoverageIdsInfo { + num_counters: next_counter_id.as_u32(), + phys_counter_for_node, + term_for_bcb: node_counters, + expressions, + }) } fn all_coverage_in_mir_body<'a, 'tcx>( @@ -139,94 +157,3 @@ fn is_inlined(body: &Body<'_>, statement: &Statement<'_>) -> bool { let scope_data = &body.source_scopes[statement.source_info.scope]; scope_data.inlined.is_some() || scope_data.inlined_parent_scope.is_some() } - -/// Identify expressions that will always have a value of zero, and note their -/// IDs in a `DenseBitSet`. Mappings that refer to a zero expression can instead -/// become mappings to a constant zero value. -/// -/// This function mainly exists to preserve the simplifications that were -/// already being performed by the Rust-side expression renumbering, so that -/// the resulting coverage mappings don't get worse. -fn identify_zero_expressions( - fn_cov_info: &FunctionCoverageInfo, - counters_seen: &DenseBitSet<CounterId>, - expressions_seen: &DenseBitSet<ExpressionId>, -) -> DenseBitSet<ExpressionId> { - // The set of expressions that either were optimized out entirely, or - // have zero as both of their operands, and will therefore always have - // a value of zero. Other expressions that refer to these as operands - // can have those operands replaced with `CovTerm::Zero`. - let mut zero_expressions = DenseBitSet::new_empty(fn_cov_info.expressions.len()); - - // Simplify a copy of each expression based on lower-numbered expressions, - // and then update the set of always-zero expressions if necessary. - // (By construction, expressions can only refer to other expressions - // that have lower IDs, so one pass is sufficient.) - for (id, expression) in fn_cov_info.expressions.iter_enumerated() { - if !expressions_seen.contains(id) { - // If an expression was not seen, it must have been optimized away, - // so any operand that refers to it can be replaced with zero. - zero_expressions.insert(id); - continue; - } - - // We don't need to simplify the actual expression data in the - // expressions list; we can just simplify a temporary copy and then - // use that to update the set of always-zero expressions. - let Expression { mut lhs, op, mut rhs } = *expression; - - // If an expression has an operand that is also an expression, the - // operand's ID must be strictly lower. This is what lets us find - // all zero expressions in one pass. - let assert_operand_expression_is_lower = |operand_id: ExpressionId| { - assert!( - operand_id < id, - "Operand {operand_id:?} should be less than {id:?} in {expression:?}", - ) - }; - - // If an operand refers to a counter or expression that is always - // zero, then that operand can be replaced with `CovTerm::Zero`. - let maybe_set_operand_to_zero = |operand: &mut CovTerm| { - if let CovTerm::Expression(id) = *operand { - assert_operand_expression_is_lower(id); - } - - if is_zero_term(&counters_seen, &zero_expressions, *operand) { - *operand = CovTerm::Zero; - } - }; - maybe_set_operand_to_zero(&mut lhs); - maybe_set_operand_to_zero(&mut rhs); - - // Coverage counter values cannot be negative, so if an expression - // involves subtraction from zero, assume that its RHS must also be zero. - // (Do this after simplifications that could set the LHS to zero.) - if lhs == CovTerm::Zero && op == Op::Subtract { - rhs = CovTerm::Zero; - } - - // After the above simplifications, if both operands are zero, then - // we know that this expression is always zero too. - if lhs == CovTerm::Zero && rhs == CovTerm::Zero { - zero_expressions.insert(id); - } - } - - zero_expressions -} - -/// Returns `true` if the given term is known to have a value of zero, taking -/// into account knowledge of which counters are unused and which expressions -/// are always zero. -fn is_zero_term( - counters_seen: &DenseBitSet<CounterId>, - zero_expressions: &DenseBitSet<ExpressionId>, - term: CovTerm, -) -> bool { - match term { - CovTerm::Zero => true, - CovTerm::Counter(id) => !counters_seen.contains(id), - CovTerm::Expression(id) => zero_expressions.contains(id), - } -} |