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use super::graph::{BasicCoverageBlock, BasicCoverageBlockData, CoverageGraph, START_BCB};
use rustc_data_structures::graph::WithNumNodes;
use rustc_index::IndexVec;
use rustc_middle::mir::{
self, AggregateKind, BasicBlock, FakeReadCause, Rvalue, Statement, StatementKind, Terminator,
TerminatorKind,
};
use rustc_span::source_map::original_sp;
use rustc_span::{BytePos, ExpnKind, MacroKind, Span, Symbol};
use std::cell::OnceCell;
pub(super) struct CoverageSpans {
/// Map from BCBs to their list of coverage spans.
bcb_to_spans: IndexVec<BasicCoverageBlock, Vec<Span>>,
}
impl CoverageSpans {
pub(super) fn generate_coverage_spans(
mir_body: &mir::Body<'_>,
fn_sig_span: Span,
body_span: Span,
basic_coverage_blocks: &CoverageGraph,
) -> Self {
let coverage_spans = CoverageSpansGenerator::generate_coverage_spans(
mir_body,
fn_sig_span,
body_span,
basic_coverage_blocks,
);
// Group the coverage spans by BCB, with the BCBs in sorted order.
let mut bcb_to_spans = IndexVec::from_elem_n(Vec::new(), basic_coverage_blocks.num_nodes());
for CoverageSpan { bcb, span, .. } in coverage_spans {
bcb_to_spans[bcb].push(span);
}
Self { bcb_to_spans }
}
pub(super) fn bcb_has_coverage_spans(&self, bcb: BasicCoverageBlock) -> bool {
!self.bcb_to_spans[bcb].is_empty()
}
pub(super) fn bcbs_with_coverage_spans(
&self,
) -> impl Iterator<Item = (BasicCoverageBlock, &[Span])> {
self.bcb_to_spans.iter_enumerated().filter_map(|(bcb, spans)| {
// Only yield BCBs that have at least one coverage span.
(!spans.is_empty()).then_some((bcb, spans.as_slice()))
})
}
}
#[derive(Debug, Copy, Clone)]
pub(super) enum CoverageStatement {
Statement(BasicBlock, Span, usize),
Terminator(BasicBlock, Span),
}
impl CoverageStatement {
pub fn span(&self) -> Span {
match self {
Self::Statement(_, span, _) | Self::Terminator(_, span) => *span,
}
}
}
/// A BCB is deconstructed into one or more `Span`s. Each `Span` maps to a `CoverageSpan` that
/// references the originating BCB and one or more MIR `Statement`s and/or `Terminator`s.
/// Initially, the `Span`s come from the `Statement`s and `Terminator`s, but subsequent
/// transforms can combine adjacent `Span`s and `CoverageSpan` from the same BCB, merging the
/// `CoverageStatement` vectors, and the `Span`s to cover the extent of the combined `Span`s.
///
/// Note: A `CoverageStatement` merged into another CoverageSpan may come from a `BasicBlock` that
/// is not part of the `CoverageSpan` bcb if the statement was included because it's `Span` matches
/// or is subsumed by the `Span` associated with this `CoverageSpan`, and it's `BasicBlock`
/// `dominates()` the `BasicBlock`s in this `CoverageSpan`.
#[derive(Debug, Clone)]
struct CoverageSpan {
pub span: Span,
pub expn_span: Span,
pub current_macro_or_none: OnceCell<Option<Symbol>>,
pub bcb: BasicCoverageBlock,
pub coverage_statements: Vec<CoverageStatement>,
pub is_closure: bool,
}
impl CoverageSpan {
pub fn for_fn_sig(fn_sig_span: Span) -> Self {
Self {
span: fn_sig_span,
expn_span: fn_sig_span,
current_macro_or_none: Default::default(),
bcb: START_BCB,
coverage_statements: vec![],
is_closure: false,
}
}
pub fn for_statement(
statement: &Statement<'_>,
span: Span,
expn_span: Span,
bcb: BasicCoverageBlock,
bb: BasicBlock,
stmt_index: usize,
) -> Self {
let is_closure = match statement.kind {
StatementKind::Assign(box (_, Rvalue::Aggregate(box ref kind, _))) => {
matches!(kind, AggregateKind::Closure(_, _) | AggregateKind::Generator(_, _, _))
}
_ => false,
};
Self {
span,
expn_span,
current_macro_or_none: Default::default(),
bcb,
coverage_statements: vec![CoverageStatement::Statement(bb, span, stmt_index)],
is_closure,
}
}
pub fn for_terminator(
span: Span,
expn_span: Span,
bcb: BasicCoverageBlock,
bb: BasicBlock,
) -> Self {
Self {
span,
expn_span,
current_macro_or_none: Default::default(),
bcb,
coverage_statements: vec![CoverageStatement::Terminator(bb, span)],
is_closure: false,
}
}
pub fn merge_from(&mut self, mut other: CoverageSpan) {
debug_assert!(self.is_mergeable(&other));
self.span = self.span.to(other.span);
self.coverage_statements.append(&mut other.coverage_statements);
}
pub fn cutoff_statements_at(&mut self, cutoff_pos: BytePos) {
self.coverage_statements.retain(|covstmt| covstmt.span().hi() <= cutoff_pos);
if let Some(highest_covstmt) =
self.coverage_statements.iter().max_by_key(|covstmt| covstmt.span().hi())
{
self.span = self.span.with_hi(highest_covstmt.span().hi());
}
}
#[inline]
pub fn is_mergeable(&self, other: &Self) -> bool {
self.is_in_same_bcb(other) && !(self.is_closure || other.is_closure)
}
#[inline]
pub fn is_in_same_bcb(&self, other: &Self) -> bool {
self.bcb == other.bcb
}
/// If the span is part of a macro, returns the macro name symbol.
pub fn current_macro(&self) -> Option<Symbol> {
self.current_macro_or_none
.get_or_init(|| {
if let ExpnKind::Macro(MacroKind::Bang, current_macro) =
self.expn_span.ctxt().outer_expn_data().kind
{
return Some(current_macro);
}
None
})
.map(|symbol| symbol)
}
/// If the span is part of a macro, and the macro is visible (expands directly to the given
/// body_span), returns the macro name symbol.
pub fn visible_macro(&self, body_span: Span) -> Option<Symbol> {
if let Some(current_macro) = self.current_macro() && self
.expn_span
.parent_callsite()
.unwrap_or_else(|| bug!("macro must have a parent"))
.eq_ctxt(body_span)
{
return Some(current_macro);
}
None
}
pub fn is_macro_expansion(&self) -> bool {
self.current_macro().is_some()
}
}
/// Converts the initial set of `CoverageSpan`s (one per MIR `Statement` or `Terminator`) into a
/// minimal set of `CoverageSpan`s, using the BCB CFG to determine where it is safe and useful to:
///
/// * Remove duplicate source code coverage regions
/// * Merge spans that represent continuous (both in source code and control flow), non-branching
/// execution
/// * Carve out (leave uncovered) any span that will be counted by another MIR (notably, closures)
struct CoverageSpansGenerator<'a, 'tcx> {
/// The MIR, used to look up `BasicBlockData`.
mir_body: &'a mir::Body<'tcx>,
/// A `Span` covering the signature of function for the MIR.
fn_sig_span: Span,
/// A `Span` covering the function body of the MIR (typically from left curly brace to right
/// curly brace).
body_span: Span,
/// The BasicCoverageBlock Control Flow Graph (BCB CFG).
basic_coverage_blocks: &'a CoverageGraph,
/// The initial set of `CoverageSpan`s, sorted by `Span` (`lo` and `hi`) and by relative
/// dominance between the `BasicCoverageBlock`s of equal `Span`s.
sorted_spans_iter: Option<std::vec::IntoIter<CoverageSpan>>,
/// The current `CoverageSpan` to compare to its `prev`, to possibly merge, discard, force the
/// discard of the `prev` (and or `pending_dups`), or keep both (with `prev` moved to
/// `pending_dups`). If `curr` is not discarded or merged, it becomes `prev` for the next
/// iteration.
some_curr: Option<CoverageSpan>,
/// The original `span` for `curr`, in case `curr.span()` is modified. The `curr_original_span`
/// **must not be mutated** (except when advancing to the next `curr`), even if `curr.span()`
/// is mutated.
curr_original_span: Span,
/// The CoverageSpan from a prior iteration; typically assigned from that iteration's `curr`.
/// If that `curr` was discarded, `prev` retains its value from the previous iteration.
some_prev: Option<CoverageSpan>,
/// Assigned from `curr_original_span` from the previous iteration. The `prev_original_span`
/// **must not be mutated** (except when advancing to the next `prev`), even if `prev.span()`
/// is mutated.
prev_original_span: Span,
/// A copy of the expn_span from the prior iteration.
prev_expn_span: Option<Span>,
/// One or more `CoverageSpan`s with the same `Span` but different `BasicCoverageBlock`s, and
/// no `BasicCoverageBlock` in this list dominates another `BasicCoverageBlock` in the list.
/// If a new `curr` span also fits this criteria (compared to an existing list of
/// `pending_dups`), that `curr` `CoverageSpan` moves to `prev` before possibly being added to
/// the `pending_dups` list, on the next iteration. As a result, if `prev` and `pending_dups`
/// have the same `Span`, the criteria for `pending_dups` holds for `prev` as well: a `prev`
/// with a matching `Span` does not dominate any `pending_dup` and no `pending_dup` dominates a
/// `prev` with a matching `Span`)
pending_dups: Vec<CoverageSpan>,
/// The final `CoverageSpan`s to add to the coverage map. A `Counter` or `Expression`
/// will also be injected into the MIR for each `CoverageSpan`.
refined_spans: Vec<CoverageSpan>,
}
impl<'a, 'tcx> CoverageSpansGenerator<'a, 'tcx> {
/// Generate a minimal set of `CoverageSpan`s, each representing a contiguous code region to be
/// counted.
///
/// The basic steps are:
///
/// 1. Extract an initial set of spans from the `Statement`s and `Terminator`s of each
/// `BasicCoverageBlockData`.
/// 2. Sort the spans by span.lo() (starting position). Spans that start at the same position
/// are sorted with longer spans before shorter spans; and equal spans are sorted
/// (deterministically) based on "dominator" relationship (if any).
/// 3. Traverse the spans in sorted order to identify spans that can be dropped (for instance,
/// if another span or spans are already counting the same code region), or should be merged
/// into a broader combined span (because it represents a contiguous, non-branching, and
/// uninterrupted region of source code).
///
/// Closures are exposed in their enclosing functions as `Assign` `Rvalue`s, and since
/// closures have their own MIR, their `Span` in their enclosing function should be left
/// "uncovered".
///
/// Note the resulting vector of `CoverageSpan`s may not be fully sorted (and does not need
/// to be).
pub(super) fn generate_coverage_spans(
mir_body: &'a mir::Body<'tcx>,
fn_sig_span: Span, // Ensured to be same SourceFile and SyntaxContext as `body_span`
body_span: Span,
basic_coverage_blocks: &'a CoverageGraph,
) -> Vec<CoverageSpan> {
let mut coverage_spans = Self {
mir_body,
fn_sig_span,
body_span,
basic_coverage_blocks,
sorted_spans_iter: None,
refined_spans: Vec::with_capacity(basic_coverage_blocks.num_nodes() * 2),
some_curr: None,
curr_original_span: Span::with_root_ctxt(BytePos(0), BytePos(0)),
some_prev: None,
prev_original_span: Span::with_root_ctxt(BytePos(0), BytePos(0)),
prev_expn_span: None,
pending_dups: Vec::new(),
};
let sorted_spans = coverage_spans.mir_to_initial_sorted_coverage_spans();
coverage_spans.sorted_spans_iter = Some(sorted_spans.into_iter());
coverage_spans.to_refined_spans()
}
fn mir_to_initial_sorted_coverage_spans(&self) -> Vec<CoverageSpan> {
let mut initial_spans =
Vec::<CoverageSpan>::with_capacity(self.mir_body.basic_blocks.len() * 2);
for (bcb, bcb_data) in self.basic_coverage_blocks.iter_enumerated() {
initial_spans.extend(self.bcb_to_initial_coverage_spans(bcb, bcb_data));
}
if initial_spans.is_empty() {
// This can happen if, for example, the function is unreachable (contains only a
// `BasicBlock`(s) with an `Unreachable` terminator).
return initial_spans;
}
initial_spans.push(CoverageSpan::for_fn_sig(self.fn_sig_span));
initial_spans.sort_by(|a, b| {
// First sort by span start.
Ord::cmp(&a.span.lo(), &b.span.lo())
// If span starts are the same, sort by span end in reverse order.
// This ensures that if spans A and B are adjacent in the list,
// and they overlap but are not equal, then either:
// - Span A extends further left, or
// - Both have the same start and span A extends further right
.then_with(|| Ord::cmp(&a.span.hi(), &b.span.hi()).reverse())
// If both spans are equal, sort the BCBs in dominator order,
// so that dominating BCBs come before other BCBs they dominate.
.then_with(|| self.basic_coverage_blocks.cmp_in_dominator_order(a.bcb, b.bcb))
// If two spans are otherwise identical, put closure spans first,
// as this seems to be what the refinement step expects.
.then_with(|| Ord::cmp(&a.is_closure, &b.is_closure).reverse())
});
initial_spans
}
/// Iterate through the sorted `CoverageSpan`s, and return the refined list of merged and
/// de-duplicated `CoverageSpan`s.
fn to_refined_spans(mut self) -> Vec<CoverageSpan> {
while self.next_coverage_span() {
if self.some_prev.is_none() {
debug!(" initial span");
self.check_invoked_macro_name_span();
} else if self.curr().is_mergeable(self.prev()) {
debug!(" same bcb (and neither is a closure), merge with prev={:?}", self.prev());
let prev = self.take_prev();
self.curr_mut().merge_from(prev);
self.check_invoked_macro_name_span();
// Note that curr.span may now differ from curr_original_span
} else if self.prev_ends_before_curr() {
debug!(
" different bcbs and disjoint spans, so keep curr for next iter, and add \
prev={:?}",
self.prev()
);
let prev = self.take_prev();
self.push_refined_span(prev);
self.check_invoked_macro_name_span();
} else if self.prev().is_closure {
// drop any equal or overlapping span (`curr`) and keep `prev` to test again in the
// next iter
debug!(
" curr overlaps a closure (prev). Drop curr and keep prev for next iter. \
prev={:?}",
self.prev()
);
self.take_curr();
} else if self.curr().is_closure {
self.carve_out_span_for_closure();
} else if self.prev_original_span == self.curr().span {
// Note that this compares the new (`curr`) span to `prev_original_span`.
// In this branch, the actual span byte range of `prev_original_span` is not
// important. What is important is knowing whether the new `curr` span was
// **originally** the same as the original span of `prev()`. The original spans
// reflect their original sort order, and for equal spans, conveys a partial
// ordering based on CFG dominator priority.
if self.prev().is_macro_expansion() && self.curr().is_macro_expansion() {
// Macros that expand to include branching (such as
// `assert_eq!()`, `assert_ne!()`, `info!()`, `debug!()`, or
// `trace!()`) typically generate callee spans with identical
// ranges (typically the full span of the macro) for all
// `BasicBlocks`. This makes it impossible to distinguish
// the condition (`if val1 != val2`) from the optional
// branched statements (such as the call to `panic!()` on
// assert failure). In this case it is better (or less
// worse) to drop the optional branch bcbs and keep the
// non-conditional statements, to count when reached.
debug!(
" curr and prev are part of a macro expansion, and curr has the same span \
as prev, but is in a different bcb. Drop curr and keep prev for next iter. \
prev={:?}",
self.prev()
);
self.take_curr();
} else {
self.hold_pending_dups_unless_dominated();
}
} else {
self.cutoff_prev_at_overlapping_curr();
self.check_invoked_macro_name_span();
}
}
debug!(" AT END, adding last prev={:?}", self.prev());
let prev = self.take_prev();
let pending_dups = self.pending_dups.split_off(0);
for dup in pending_dups {
debug!(" ...adding at least one pending dup={:?}", dup);
self.push_refined_span(dup);
}
// Async functions wrap a closure that implements the body to be executed. The enclosing
// function is called and returns an `impl Future` without initially executing any of the
// body. To avoid showing the return from the enclosing function as a "covered" return from
// the closure, the enclosing function's `TerminatorKind::Return`s `CoverageSpan` is
// excluded. The closure's `Return` is the only one that will be counted. This provides
// adequate coverage, and more intuitive counts. (Avoids double-counting the closing brace
// of the function body.)
let body_ends_with_closure = if let Some(last_covspan) = self.refined_spans.last() {
last_covspan.is_closure && last_covspan.span.hi() == self.body_span.hi()
} else {
false
};
if !body_ends_with_closure {
self.push_refined_span(prev);
}
// Remove `CoverageSpan`s derived from closures, originally added to ensure the coverage
// regions for the current function leave room for the closure's own coverage regions
// (injected separately, from the closure's own MIR).
self.refined_spans.retain(|covspan| !covspan.is_closure);
self.refined_spans
}
fn push_refined_span(&mut self, covspan: CoverageSpan) {
let len = self.refined_spans.len();
if len > 0 {
let last = &mut self.refined_spans[len - 1];
if last.is_mergeable(&covspan) {
debug!(
"merging new refined span with last refined span, last={:?}, covspan={:?}",
last, covspan
);
last.merge_from(covspan);
return;
}
}
self.refined_spans.push(covspan)
}
fn check_invoked_macro_name_span(&mut self) {
if let Some(visible_macro) = self.curr().visible_macro(self.body_span) {
if !self
.prev_expn_span
.is_some_and(|prev_expn_span| self.curr().expn_span.ctxt() == prev_expn_span.ctxt())
{
let merged_prefix_len = self.curr_original_span.lo() - self.curr().span.lo();
let after_macro_bang =
merged_prefix_len + BytePos(visible_macro.as_str().len() as u32 + 1);
let mut macro_name_cov = self.curr().clone();
self.curr_mut().span =
self.curr().span.with_lo(self.curr().span.lo() + after_macro_bang);
macro_name_cov.span =
macro_name_cov.span.with_hi(macro_name_cov.span.lo() + after_macro_bang);
debug!(
" and curr starts a new macro expansion, so add a new span just for \
the macro `{}!`, new span={:?}",
visible_macro, macro_name_cov
);
self.push_refined_span(macro_name_cov);
}
}
}
// Generate a set of `CoverageSpan`s from the filtered set of `Statement`s and `Terminator`s of
// the `BasicBlock`(s) in the given `BasicCoverageBlockData`. One `CoverageSpan` is generated
// for each `Statement` and `Terminator`. (Note that subsequent stages of coverage analysis will
// merge some `CoverageSpan`s, at which point a `CoverageSpan` may represent multiple
// `Statement`s and/or `Terminator`s.)
fn bcb_to_initial_coverage_spans(
&self,
bcb: BasicCoverageBlock,
bcb_data: &'a BasicCoverageBlockData,
) -> Vec<CoverageSpan> {
bcb_data
.basic_blocks
.iter()
.flat_map(|&bb| {
let data = &self.mir_body[bb];
data.statements
.iter()
.enumerate()
.filter_map(move |(index, statement)| {
filtered_statement_span(statement).map(|span| {
CoverageSpan::for_statement(
statement,
function_source_span(span, self.body_span),
span,
bcb,
bb,
index,
)
})
})
.chain(filtered_terminator_span(data.terminator()).map(|span| {
CoverageSpan::for_terminator(
function_source_span(span, self.body_span),
span,
bcb,
bb,
)
}))
})
.collect()
}
fn curr(&self) -> &CoverageSpan {
self.some_curr
.as_ref()
.unwrap_or_else(|| bug!("invalid attempt to unwrap a None some_curr"))
}
fn curr_mut(&mut self) -> &mut CoverageSpan {
self.some_curr
.as_mut()
.unwrap_or_else(|| bug!("invalid attempt to unwrap a None some_curr"))
}
fn prev(&self) -> &CoverageSpan {
self.some_prev
.as_ref()
.unwrap_or_else(|| bug!("invalid attempt to unwrap a None some_prev"))
}
fn prev_mut(&mut self) -> &mut CoverageSpan {
self.some_prev
.as_mut()
.unwrap_or_else(|| bug!("invalid attempt to unwrap a None some_prev"))
}
fn take_prev(&mut self) -> CoverageSpan {
self.some_prev.take().unwrap_or_else(|| bug!("invalid attempt to unwrap a None some_prev"))
}
/// If there are `pending_dups` but `prev` is not a matching dup (`prev.span` doesn't match the
/// `pending_dups` spans), then one of the following two things happened during the previous
/// iteration:
/// * the previous `curr` span (which is now `prev`) was not a duplicate of the pending_dups
/// (in which case there should be at least two spans in `pending_dups`); or
/// * the `span` of `prev` was modified by `curr_mut().merge_from(prev)` (in which case
/// `pending_dups` could have as few as one span)
/// In either case, no more spans will match the span of `pending_dups`, so
/// add the `pending_dups` if they don't overlap `curr`, and clear the list.
fn check_pending_dups(&mut self) {
if let Some(dup) = self.pending_dups.last() && dup.span != self.prev().span {
debug!(
" SAME spans, but pending_dups are NOT THE SAME, so BCBs matched on \
previous iteration, or prev started a new disjoint span"
);
if dup.span.hi() <= self.curr().span.lo() {
let pending_dups = self.pending_dups.split_off(0);
for dup in pending_dups.into_iter() {
debug!(" ...adding at least one pending={:?}", dup);
self.push_refined_span(dup);
}
} else {
self.pending_dups.clear();
}
}
}
/// Advance `prev` to `curr` (if any), and `curr` to the next `CoverageSpan` in sorted order.
fn next_coverage_span(&mut self) -> bool {
if let Some(curr) = self.some_curr.take() {
self.prev_expn_span = Some(curr.expn_span);
self.some_prev = Some(curr);
self.prev_original_span = self.curr_original_span;
}
while let Some(curr) = self.sorted_spans_iter.as_mut().unwrap().next() {
debug!("FOR curr={:?}", curr);
if self.some_prev.is_some() && self.prev_starts_after_next(&curr) {
debug!(
" prev.span starts after curr.span, so curr will be dropped (skipping past \
closure?); prev={:?}",
self.prev()
);
} else {
// Save a copy of the original span for `curr` in case the `CoverageSpan` is changed
// by `self.curr_mut().merge_from(prev)`.
self.curr_original_span = curr.span;
self.some_curr.replace(curr);
self.check_pending_dups();
return true;
}
}
false
}
/// If called, then the next call to `next_coverage_span()` will *not* update `prev` with the
/// `curr` coverage span.
fn take_curr(&mut self) -> CoverageSpan {
self.some_curr.take().unwrap_or_else(|| bug!("invalid attempt to unwrap a None some_curr"))
}
/// Returns true if the curr span should be skipped because prev has already advanced beyond the
/// end of curr. This can only happen if a prior iteration updated `prev` to skip past a region
/// of code, such as skipping past a closure.
fn prev_starts_after_next(&self, next_curr: &CoverageSpan) -> bool {
self.prev().span.lo() > next_curr.span.lo()
}
/// Returns true if the curr span starts past the end of the prev span, which means they don't
/// overlap, so we now know the prev can be added to the refined coverage spans.
fn prev_ends_before_curr(&self) -> bool {
self.prev().span.hi() <= self.curr().span.lo()
}
/// If `prev`s span extends left of the closure (`curr`), carve out the closure's span from
/// `prev`'s span. (The closure's coverage counters will be injected when processing the
/// closure's own MIR.) Add the portion of the span to the left of the closure; and if the span
/// extends to the right of the closure, update `prev` to that portion of the span. For any
/// `pending_dups`, repeat the same process.
fn carve_out_span_for_closure(&mut self) {
let curr_span = self.curr().span;
let left_cutoff = curr_span.lo();
let right_cutoff = curr_span.hi();
let has_pre_closure_span = self.prev().span.lo() < right_cutoff;
let has_post_closure_span = self.prev().span.hi() > right_cutoff;
let mut pending_dups = self.pending_dups.split_off(0);
if has_pre_closure_span {
let mut pre_closure = self.prev().clone();
pre_closure.span = pre_closure.span.with_hi(left_cutoff);
debug!(" prev overlaps a closure. Adding span for pre_closure={:?}", pre_closure);
if !pending_dups.is_empty() {
for mut dup in pending_dups.iter().cloned() {
dup.span = dup.span.with_hi(left_cutoff);
debug!(" ...and at least one pre_closure dup={:?}", dup);
self.push_refined_span(dup);
}
}
self.push_refined_span(pre_closure);
}
if has_post_closure_span {
// Mutate `prev.span()` to start after the closure (and discard curr).
// (**NEVER** update `prev_original_span` because it affects the assumptions
// about how the `CoverageSpan`s are ordered.)
self.prev_mut().span = self.prev().span.with_lo(right_cutoff);
debug!(" Mutated prev.span to start after the closure. prev={:?}", self.prev());
for dup in pending_dups.iter_mut() {
debug!(" ...and at least one overlapping dup={:?}", dup);
dup.span = dup.span.with_lo(right_cutoff);
}
self.pending_dups.append(&mut pending_dups);
let closure_covspan = self.take_curr();
self.push_refined_span(closure_covspan); // since self.prev() was already updated
} else {
pending_dups.clear();
}
}
/// Called if `curr.span` equals `prev_original_span` (and potentially equal to all
/// `pending_dups` spans, if any). Keep in mind, `prev.span()` may have been changed.
/// If prev.span() was merged into other spans (with matching BCB, for instance),
/// `prev.span.hi()` will be greater than (further right of) `prev_original_span.hi()`.
/// If prev.span() was split off to the right of a closure, prev.span().lo() will be
/// greater than prev_original_span.lo(). The actual span of `prev_original_span` is
/// not as important as knowing that `prev()` **used to have the same span** as `curr()`,
/// which means their sort order is still meaningful for determining the dominator
/// relationship.
///
/// When two `CoverageSpan`s have the same `Span`, dominated spans can be discarded; but if
/// neither `CoverageSpan` dominates the other, both (or possibly more than two) are held,
/// until their disposition is determined. In this latter case, the `prev` dup is moved into
/// `pending_dups` so the new `curr` dup can be moved to `prev` for the next iteration.
fn hold_pending_dups_unless_dominated(&mut self) {
// Equal coverage spans are ordered by dominators before dominated (if any), so it should be
// impossible for `curr` to dominate any previous `CoverageSpan`.
debug_assert!(!self.span_bcb_dominates(self.curr(), self.prev()));
let initial_pending_count = self.pending_dups.len();
if initial_pending_count > 0 {
let mut pending_dups = self.pending_dups.split_off(0);
pending_dups.retain(|dup| !self.span_bcb_dominates(dup, self.curr()));
self.pending_dups.append(&mut pending_dups);
if self.pending_dups.len() < initial_pending_count {
debug!(
" discarded {} of {} pending_dups that dominated curr",
initial_pending_count - self.pending_dups.len(),
initial_pending_count
);
}
}
if self.span_bcb_dominates(self.prev(), self.curr()) {
debug!(
" different bcbs but SAME spans, and prev dominates curr. Discard prev={:?}",
self.prev()
);
self.cutoff_prev_at_overlapping_curr();
// If one span dominates the other, associate the span with the code from the dominated
// block only (`curr`), and discard the overlapping portion of the `prev` span. (Note
// that if `prev.span` is wider than `prev_original_span`, a `CoverageSpan` will still
// be created for `prev`s block, for the non-overlapping portion, left of `curr.span`.)
//
// For example:
// match somenum {
// x if x < 1 => { ... }
// }...
//
// The span for the first `x` is referenced by both the pattern block (every time it is
// evaluated) and the arm code (only when matched). The counter will be applied only to
// the dominated block. This allows coverage to track and highlight things like the
// assignment of `x` above, if the branch is matched, making `x` available to the arm
// code; and to track and highlight the question mark `?` "try" operator at the end of
// a function call returning a `Result`, so the `?` is covered when the function returns
// an `Err`, and not counted as covered if the function always returns `Ok`.
} else {
// Save `prev` in `pending_dups`. (`curr` will become `prev` in the next iteration.)
// If the `curr` CoverageSpan is later discarded, `pending_dups` can be discarded as
// well; but if `curr` is added to refined_spans, the `pending_dups` will also be added.
debug!(
" different bcbs but SAME spans, and neither dominates, so keep curr for \
next iter, and, pending upcoming spans (unless overlapping) add prev={:?}",
self.prev()
);
let prev = self.take_prev();
self.pending_dups.push(prev);
}
}
/// `curr` overlaps `prev`. If `prev`s span extends left of `curr`s span, keep _only_
/// statements that end before `curr.lo()` (if any), and add the portion of the
/// combined span for those statements. Any other statements have overlapping spans
/// that can be ignored because `curr` and/or other upcoming statements/spans inside
/// the overlap area will produce their own counters. This disambiguation process
/// avoids injecting multiple counters for overlapping spans, and the potential for
/// double-counting.
fn cutoff_prev_at_overlapping_curr(&mut self) {
debug!(
" different bcbs, overlapping spans, so ignore/drop pending and only add prev \
if it has statements that end before curr; prev={:?}",
self.prev()
);
if self.pending_dups.is_empty() {
let curr_span = self.curr().span;
self.prev_mut().cutoff_statements_at(curr_span.lo());
if self.prev().coverage_statements.is_empty() {
debug!(" ... no non-overlapping statements to add");
} else {
debug!(" ... adding modified prev={:?}", self.prev());
let prev = self.take_prev();
self.push_refined_span(prev);
}
} else {
// with `pending_dups`, `prev` cannot have any statements that don't overlap
self.pending_dups.clear();
}
}
fn span_bcb_dominates(&self, dom_covspan: &CoverageSpan, covspan: &CoverageSpan) -> bool {
self.basic_coverage_blocks.dominates(dom_covspan.bcb, covspan.bcb)
}
}
/// If the MIR `Statement` has a span contributive to computing coverage spans,
/// return it; otherwise return `None`.
fn filtered_statement_span(statement: &Statement<'_>) -> Option<Span> {
match statement.kind {
// These statements have spans that are often outside the scope of the executed source code
// for their parent `BasicBlock`.
StatementKind::StorageLive(_)
| StatementKind::StorageDead(_)
// Coverage should not be encountered, but don't inject coverage coverage
| StatementKind::Coverage(_)
// Ignore `ConstEvalCounter`s
| StatementKind::ConstEvalCounter
// Ignore `Nop`s
| StatementKind::Nop => None,
// FIXME(#78546): MIR InstrumentCoverage - Can the source_info.span for `FakeRead`
// statements be more consistent?
//
// FakeReadCause::ForGuardBinding, in this example:
// match somenum {
// x if x < 1 => { ... }
// }...
// The BasicBlock within the match arm code included one of these statements, but the span
// for it covered the `1` in this source. The actual statements have nothing to do with that
// source span:
// FakeRead(ForGuardBinding, _4);
// where `_4` is:
// _4 = &_1; (at the span for the first `x`)
// and `_1` is the `Place` for `somenum`.
//
// If and when the Issue is resolved, remove this special case match pattern:
StatementKind::FakeRead(box (FakeReadCause::ForGuardBinding, _)) => None,
// Retain spans from all other statements
StatementKind::FakeRead(box (_, _)) // Not including `ForGuardBinding`
| StatementKind::Intrinsic(..)
| StatementKind::Assign(_)
| StatementKind::SetDiscriminant { .. }
| StatementKind::Deinit(..)
| StatementKind::Retag(_, _)
| StatementKind::PlaceMention(..)
| StatementKind::AscribeUserType(_, _) => {
Some(statement.source_info.span)
}
}
}
/// If the MIR `Terminator` has a span contributive to computing coverage spans,
/// return it; otherwise return `None`.
fn filtered_terminator_span(terminator: &Terminator<'_>) -> Option<Span> {
match terminator.kind {
// These terminators have spans that don't positively contribute to computing a reasonable
// span of actually executed source code. (For example, SwitchInt terminators extracted from
// an `if condition { block }` has a span that includes the executed block, if true,
// but for coverage, the code region executed, up to *and* through the SwitchInt,
// actually stops before the if's block.)
TerminatorKind::Unreachable // Unreachable blocks are not connected to the MIR CFG
| TerminatorKind::Assert { .. }
| TerminatorKind::Drop { .. }
| TerminatorKind::SwitchInt { .. }
// For `FalseEdge`, only the `real` branch is taken, so it is similar to a `Goto`.
| TerminatorKind::FalseEdge { .. }
| TerminatorKind::Goto { .. } => None,
// Call `func` operand can have a more specific span when part of a chain of calls
| TerminatorKind::Call { ref func, .. } => {
let mut span = terminator.source_info.span;
if let mir::Operand::Constant(box constant) = func {
if constant.span.lo() > span.lo() {
span = span.with_lo(constant.span.lo());
}
}
Some(span)
}
// Retain spans from all other terminators
TerminatorKind::UnwindResume
| TerminatorKind::UnwindTerminate(_)
| TerminatorKind::Return
| TerminatorKind::Yield { .. }
| TerminatorKind::GeneratorDrop
| TerminatorKind::FalseUnwind { .. }
| TerminatorKind::InlineAsm { .. } => {
Some(terminator.source_info.span)
}
}
}
/// Returns an extrapolated span (pre-expansion[^1]) corresponding to a range
/// within the function's body source. This span is guaranteed to be contained
/// within, or equal to, the `body_span`. If the extrapolated span is not
/// contained within the `body_span`, the `body_span` is returned.
///
/// [^1]Expansions result from Rust syntax including macros, syntactic sugar,
/// etc.).
#[inline]
fn function_source_span(span: Span, body_span: Span) -> Span {
let original_span = original_sp(span, body_span).with_ctxt(body_span.ctxt());
if body_span.contains(original_span) { original_span } else { body_span }
}