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coverage: In the visitor, track max counter/expression IDs without +1

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This makes the visitor track the highest seen counter/expression IDs directly,
and only add +1 (to convert to a vector length) at the very end.
This commit is contained in:
Zalathar 2023-09-06 12:37:38 +10:00
parent f191b1c2fc
commit e54204c8e9
1 changed files with 25 additions and 25 deletions
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50
compiler/rustc_mir_transform/src/coverage/query.rs
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@ -13,15 +13,10 @@ pub(crate) fn provide(providers: &mut Providers) {
providers.covered_code_regions = |tcx, def_id| covered_code_regions(tcx, def_id);
}
/// The `num_counters` argument to `llvm.instrprof.increment` is the max counter_id + 1, or in
/// other words, the number of counter value references injected into the MIR (plus 1 for the
/// reserved `ZERO` counter, which uses counter ID `0` when included in an expression). Injected
/// counters have a counter ID from `1..num_counters-1`.
///
/// `num_expressions` is the number of counter expressions added to the MIR body.
///
/// Both `num_counters` and `num_expressions` are used to initialize new vectors, during backend
/// code generate, to lookup counters and expressions by simple u32 indexes.
/// Coverage codegen needs to know the total number of counter IDs and expression IDs that have
/// been used by a function's coverage mappings. These totals are used to create vectors to hold
/// the relevant counter and expression data, and the maximum counter ID (+ 1) is also needed by
/// the `llvm.instrprof.increment` intrinsic.
///
/// MIR optimization may split and duplicate some BasicBlock sequences, or optimize out some code
/// including injected counters. (It is OK if some counters are optimized out, but those counters
@ -34,28 +29,27 @@ pub(crate) fn provide(providers: &mut Providers) {
/// determining the maximum counter/expression ID, even if the underlying counter/expression is
/// no longer present.
struct CoverageVisitor {
info: CoverageInfo,
max_counter_id: CounterId,
max_expression_id: ExpressionId,
}
impl CoverageVisitor {
/// Updates `num_counters` to the maximum encountered counter ID plus 1.
/// Updates `max_counter_id` to the maximum encountered counter ID.
#[inline(always)]
fn update_num_counters(&mut self, counter_id: CounterId) {
let counter_id = counter_id.as_u32();
self.info.num_counters = std::cmp::max(self.info.num_counters, counter_id + 1);
fn update_max_counter_id(&mut self, counter_id: CounterId) {
self.max_counter_id = self.max_counter_id.max(counter_id);
}
/// Updates `num_expressions` to the maximum encountered expression ID plus 1.
/// Updates `max_expression_id` to the maximum encountered expression ID.
#[inline(always)]
fn update_num_expressions(&mut self, expression_id: ExpressionId) {
let expression_id = expression_id.as_u32();
self.info.num_expressions = std::cmp::max(self.info.num_expressions, expression_id + 1);
fn update_max_expression_id(&mut self, expression_id: ExpressionId) {
self.max_expression_id = self.max_expression_id.max(expression_id);
}
fn update_from_expression_operand(&mut self, operand: Operand) {
match operand {
Operand::Counter(id) => self.update_num_counters(id),
Operand::Expression(id) => self.update_num_expressions(id),
Operand::Counter(id) => self.update_max_counter_id(id),
Operand::Expression(id) => self.update_max_expression_id(id),
Operand::Zero => {}
}
}
@ -68,9 +62,9 @@ impl CoverageVisitor {
fn visit_coverage(&mut self, coverage: &Coverage) {
match coverage.kind {
CoverageKind::Counter { id, .. } => self.update_num_counters(id),
CoverageKind::Counter { id, .. } => self.update_max_counter_id(id),
CoverageKind::Expression { id, lhs, rhs, .. } => {
self.update_num_expressions(id);
self.update_max_expression_id(id);
self.update_from_expression_operand(lhs);
self.update_from_expression_operand(rhs);
}
@ -82,12 +76,18 @@ impl CoverageVisitor {
fn coverageinfo<'tcx>(tcx: TyCtxt<'tcx>, instance_def: ty::InstanceDef<'tcx>) -> CoverageInfo {
let mir_body = tcx.instance_mir(instance_def);
let mut coverage_visitor =
CoverageVisitor { info: CoverageInfo { num_counters: 0, num_expressions: 0 } };
let mut coverage_visitor = CoverageVisitor {
max_counter_id: CounterId::START,
max_expression_id: ExpressionId::START,
};
coverage_visitor.visit_body(mir_body);
coverage_visitor.info
// Add 1 to the highest IDs to get the total number of IDs.
CoverageInfo {
num_counters: (coverage_visitor.max_counter_id + 1).as_u32(),
num_expressions: (coverage_visitor.max_expression_id + 1).as_u32(),
}
}
fn covered_code_regions(tcx: TyCtxt<'_>, def_id: DefId) -> Vec<&CodeRegion> {