2022-01-15 21:26:25 +01:00

588 lines
24 KiB
Rust

pub mod query;
mod counters;
mod debug;
mod graph;
mod spans;
#[cfg(test)]
mod tests;
use counters::CoverageCounters;
use graph::{BasicCoverageBlock, BasicCoverageBlockData, CoverageGraph};
use spans::{CoverageSpan, CoverageSpans};
use crate::MirPass;
use rustc_data_structures::graph::WithNumNodes;
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
use rustc_data_structures::sync::Lrc;
use rustc_index::vec::IndexVec;
use rustc_middle::hir;
use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
use rustc_middle::mir::coverage::*;
use rustc_middle::mir::dump_enabled;
use rustc_middle::mir::{
self, BasicBlock, BasicBlockData, Coverage, SourceInfo, Statement, StatementKind, Terminator,
TerminatorKind,
};
use rustc_middle::ty::TyCtxt;
use rustc_span::def_id::DefId;
use rustc_span::source_map::SourceMap;
use rustc_span::{CharPos, ExpnKind, Pos, SourceFile, Span, Symbol};
/// A simple error message wrapper for `coverage::Error`s.
#[derive(Debug)]
struct Error {
message: String,
}
impl Error {
pub fn from_string<T>(message: String) -> Result<T, Error> {
Err(Self { message })
}
}
/// Inserts `StatementKind::Coverage` statements that either instrument the binary with injected
/// counters, via intrinsic `llvm.instrprof.increment`, and/or inject metadata used during codegen
/// to construct the coverage map.
pub struct InstrumentCoverage;
impl<'tcx> MirPass<'tcx> for InstrumentCoverage {
fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
sess.instrument_coverage()
}
fn run_pass(&self, tcx: TyCtxt<'tcx>, mir_body: &mut mir::Body<'tcx>) {
let mir_source = mir_body.source;
// If the InstrumentCoverage pass is called on promoted MIRs, skip them.
// See: https://github.com/rust-lang/rust/pull/73011#discussion_r438317601
if mir_source.promoted.is_some() {
trace!(
"InstrumentCoverage skipped for {:?} (already promoted for Miri evaluation)",
mir_source.def_id()
);
return;
}
let is_fn_like =
tcx.hir().get_by_def_id(mir_source.def_id().expect_local()).fn_kind().is_some();
// Only instrument functions, methods, and closures (not constants since they are evaluated
// at compile time by Miri).
// FIXME(#73156): Handle source code coverage in const eval, but note, if and when const
// expressions get coverage spans, we will probably have to "carve out" space for const
// expressions from coverage spans in enclosing MIR's, like we do for closures. (That might
// be tricky if const expressions have no corresponding statements in the enclosing MIR.
// Closures are carved out by their initial `Assign` statement.)
if !is_fn_like {
trace!("InstrumentCoverage skipped for {:?} (not an fn-like)", mir_source.def_id());
return;
}
match mir_body.basic_blocks()[mir::START_BLOCK].terminator().kind {
TerminatorKind::Unreachable => {
trace!("InstrumentCoverage skipped for unreachable `START_BLOCK`");
return;
}
_ => {}
}
let codegen_fn_attrs = tcx.codegen_fn_attrs(mir_source.def_id());
if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::NO_COVERAGE) {
return;
}
trace!("InstrumentCoverage starting for {:?}", mir_source.def_id());
Instrumentor::new(&self.name(), tcx, mir_body).inject_counters();
trace!("InstrumentCoverage done for {:?}", mir_source.def_id());
}
}
struct Instrumentor<'a, 'tcx> {
pass_name: &'a str,
tcx: TyCtxt<'tcx>,
mir_body: &'a mut mir::Body<'tcx>,
source_file: Lrc<SourceFile>,
fn_sig_span: Span,
body_span: Span,
basic_coverage_blocks: CoverageGraph,
coverage_counters: CoverageCounters,
}
impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
fn new(pass_name: &'a str, tcx: TyCtxt<'tcx>, mir_body: &'a mut mir::Body<'tcx>) -> Self {
let source_map = tcx.sess.source_map();
let def_id = mir_body.source.def_id();
let (some_fn_sig, hir_body) = fn_sig_and_body(tcx, def_id);
let body_span = get_body_span(tcx, hir_body, mir_body);
let source_file = source_map.lookup_source_file(body_span.lo());
let fn_sig_span = match some_fn_sig.filter(|fn_sig| {
fn_sig.span.ctxt() == body_span.ctxt()
&& Lrc::ptr_eq(&source_file, &source_map.lookup_source_file(fn_sig.span.lo()))
}) {
Some(fn_sig) => fn_sig.span.with_hi(body_span.lo()),
None => body_span.shrink_to_lo(),
};
debug!(
"instrumenting {}: {:?}, fn sig span: {:?}, body span: {:?}",
if tcx.is_closure(def_id) { "closure" } else { "function" },
def_id,
fn_sig_span,
body_span
);
let function_source_hash = hash_mir_source(tcx, hir_body);
let basic_coverage_blocks = CoverageGraph::from_mir(mir_body);
Self {
pass_name,
tcx,
mir_body,
source_file,
fn_sig_span,
body_span,
basic_coverage_blocks,
coverage_counters: CoverageCounters::new(function_source_hash),
}
}
fn inject_counters(&'a mut self) {
let tcx = self.tcx;
let mir_source = self.mir_body.source;
let def_id = mir_source.def_id();
let fn_sig_span = self.fn_sig_span;
let body_span = self.body_span;
let mut graphviz_data = debug::GraphvizData::new();
let mut debug_used_expressions = debug::UsedExpressions::new();
let dump_mir = dump_enabled(tcx, self.pass_name, def_id);
let dump_graphviz = dump_mir && tcx.sess.opts.debugging_opts.dump_mir_graphviz;
let dump_spanview = dump_mir && tcx.sess.opts.debugging_opts.dump_mir_spanview.is_some();
if dump_graphviz {
graphviz_data.enable();
self.coverage_counters.enable_debug();
}
if dump_graphviz || level_enabled!(tracing::Level::DEBUG) {
debug_used_expressions.enable();
}
////////////////////////////////////////////////////
// Compute `CoverageSpan`s from the `CoverageGraph`.
let coverage_spans = CoverageSpans::generate_coverage_spans(
&self.mir_body,
fn_sig_span,
body_span,
&self.basic_coverage_blocks,
);
if dump_spanview {
debug::dump_coverage_spanview(
tcx,
self.mir_body,
&self.basic_coverage_blocks,
self.pass_name,
body_span,
&coverage_spans,
);
}
////////////////////////////////////////////////////
// Create an optimized mix of `Counter`s and `Expression`s for the `CoverageGraph`. Ensure
// every `CoverageSpan` has a `Counter` or `Expression` assigned to its `BasicCoverageBlock`
// and all `Expression` dependencies (operands) are also generated, for any other
// `BasicCoverageBlock`s not already associated with a `CoverageSpan`.
//
// Intermediate expressions (used to compute other `Expression` values), which have no
// direct associate to any `BasicCoverageBlock`, are returned in the method `Result`.
let intermediate_expressions_or_error = self
.coverage_counters
.make_bcb_counters(&mut self.basic_coverage_blocks, &coverage_spans);
let (result, intermediate_expressions) = match intermediate_expressions_or_error {
Ok(intermediate_expressions) => {
// If debugging, add any intermediate expressions (which are not associated with any
// BCB) to the `debug_used_expressions` map.
if debug_used_expressions.is_enabled() {
for intermediate_expression in &intermediate_expressions {
debug_used_expressions.add_expression_operands(intermediate_expression);
}
}
////////////////////////////////////////////////////
// Remove the counter or edge counter from of each `CoverageSpan`s associated
// `BasicCoverageBlock`, and inject a `Coverage` statement into the MIR.
//
// `Coverage` statements injected from `CoverageSpan`s will include the code regions
// (source code start and end positions) to be counted by the associated counter.
//
// These `CoverageSpan`-associated counters are removed from their associated
// `BasicCoverageBlock`s so that the only remaining counters in the `CoverageGraph`
// are indirect counters (to be injected next, without associated code regions).
self.inject_coverage_span_counters(
coverage_spans,
&mut graphviz_data,
&mut debug_used_expressions,
);
////////////////////////////////////////////////////
// For any remaining `BasicCoverageBlock` counters (that were not associated with
// any `CoverageSpan`), inject `Coverage` statements (_without_ code region `Span`s)
// to ensure `BasicCoverageBlock` counters that other `Expression`s may depend on
// are in fact counted, even though they don't directly contribute to counting
// their own independent code region's coverage.
self.inject_indirect_counters(&mut graphviz_data, &mut debug_used_expressions);
// Intermediate expressions will be injected as the final step, after generating
// debug output, if any.
////////////////////////////////////////////////////
(Ok(()), intermediate_expressions)
}
Err(e) => (Err(e), Vec::new()),
};
if graphviz_data.is_enabled() {
// Even if there was an error, a partial CoverageGraph can still generate a useful
// graphviz output.
debug::dump_coverage_graphviz(
tcx,
self.mir_body,
self.pass_name,
&self.basic_coverage_blocks,
&self.coverage_counters.debug_counters,
&graphviz_data,
&intermediate_expressions,
&debug_used_expressions,
);
}
if let Err(e) = result {
bug!("Error processing: {:?}: {:?}", self.mir_body.source.def_id(), e.message)
};
// Depending on current `debug_options()`, `alert_on_unused_expressions()` could panic, so
// this check is performed as late as possible, to allow other debug output (logs and dump
// files), which might be helpful in analyzing unused expressions, to still be generated.
debug_used_expressions.alert_on_unused_expressions(&self.coverage_counters.debug_counters);
////////////////////////////////////////////////////
// Finally, inject the intermediate expressions collected along the way.
for intermediate_expression in intermediate_expressions {
inject_intermediate_expression(self.mir_body, intermediate_expression);
}
}
/// Inject a counter for each `CoverageSpan`. There can be multiple `CoverageSpan`s for a given
/// BCB, but only one actual counter needs to be incremented per BCB. `bb_counters` maps each
/// `bcb` to its `Counter`, when injected. Subsequent `CoverageSpan`s for a BCB that already has
/// a `Counter` will inject an `Expression` instead, and compute its value by adding `ZERO` to
/// the BCB `Counter` value.
///
/// If debugging, add every BCB `Expression` associated with a `CoverageSpan`s to the
/// `used_expression_operands` map.
fn inject_coverage_span_counters(
&mut self,
coverage_spans: Vec<CoverageSpan>,
graphviz_data: &mut debug::GraphvizData,
debug_used_expressions: &mut debug::UsedExpressions,
) {
let tcx = self.tcx;
let source_map = tcx.sess.source_map();
let body_span = self.body_span;
let file_name = Symbol::intern(&self.source_file.name.prefer_remapped().to_string_lossy());
let mut bcb_counters = IndexVec::from_elem_n(None, self.basic_coverage_blocks.num_nodes());
for covspan in coverage_spans {
let bcb = covspan.bcb;
let span = covspan.span;
let counter_kind = if let Some(&counter_operand) = bcb_counters[bcb].as_ref() {
self.coverage_counters.make_identity_counter(counter_operand)
} else if let Some(counter_kind) = self.bcb_data_mut(bcb).take_counter() {
bcb_counters[bcb] = Some(counter_kind.as_operand_id());
debug_used_expressions.add_expression_operands(&counter_kind);
counter_kind
} else {
bug!("Every BasicCoverageBlock should have a Counter or Expression");
};
graphviz_data.add_bcb_coverage_span_with_counter(bcb, &covspan, &counter_kind);
debug!(
"Calling make_code_region(file_name={}, source_file={:?}, span={}, body_span={})",
file_name,
self.source_file,
source_map.span_to_diagnostic_string(span),
source_map.span_to_diagnostic_string(body_span)
);
inject_statement(
self.mir_body,
counter_kind,
self.bcb_leader_bb(bcb),
Some(make_code_region(source_map, file_name, &self.source_file, span, body_span)),
);
}
}
/// `inject_coverage_span_counters()` looped through the `CoverageSpan`s and injected the
/// counter from the `CoverageSpan`s `BasicCoverageBlock`, removing it from the BCB in the
/// process (via `take_counter()`).
///
/// Any other counter associated with a `BasicCoverageBlock`, or its incoming edge, but not
/// associated with a `CoverageSpan`, should only exist if the counter is an `Expression`
/// dependency (one of the expression operands). Collect them, and inject the additional
/// counters into the MIR, without a reportable coverage span.
fn inject_indirect_counters(
&mut self,
graphviz_data: &mut debug::GraphvizData,
debug_used_expressions: &mut debug::UsedExpressions,
) {
let mut bcb_counters_without_direct_coverage_spans = Vec::new();
for (target_bcb, target_bcb_data) in self.basic_coverage_blocks.iter_enumerated_mut() {
if let Some(counter_kind) = target_bcb_data.take_counter() {
bcb_counters_without_direct_coverage_spans.push((None, target_bcb, counter_kind));
}
if let Some(edge_counters) = target_bcb_data.take_edge_counters() {
for (from_bcb, counter_kind) in edge_counters {
bcb_counters_without_direct_coverage_spans.push((
Some(from_bcb),
target_bcb,
counter_kind,
));
}
}
}
// If debug is enabled, validate that every BCB or edge counter not directly associated
// with a coverage span is at least indirectly associated (it is a dependency of a BCB
// counter that _is_ associated with a coverage span).
debug_used_expressions.validate(&bcb_counters_without_direct_coverage_spans);
for (edge_from_bcb, target_bcb, counter_kind) in bcb_counters_without_direct_coverage_spans
{
debug_used_expressions.add_unused_expression_if_not_found(
&counter_kind,
edge_from_bcb,
target_bcb,
);
match counter_kind {
CoverageKind::Counter { .. } => {
let inject_to_bb = if let Some(from_bcb) = edge_from_bcb {
// The MIR edge starts `from_bb` (the outgoing / last BasicBlock in
// `from_bcb`) and ends at `to_bb` (the incoming / first BasicBlock in the
// `target_bcb`; also called the `leader_bb`).
let from_bb = self.bcb_last_bb(from_bcb);
let to_bb = self.bcb_leader_bb(target_bcb);
let new_bb = inject_edge_counter_basic_block(self.mir_body, from_bb, to_bb);
graphviz_data.set_edge_counter(from_bcb, new_bb, &counter_kind);
debug!(
"Edge {:?} (last {:?}) -> {:?} (leader {:?}) requires a new MIR \
BasicBlock {:?}, for unclaimed edge counter {}",
edge_from_bcb,
from_bb,
target_bcb,
to_bb,
new_bb,
self.format_counter(&counter_kind),
);
new_bb
} else {
let target_bb = self.bcb_last_bb(target_bcb);
graphviz_data.add_bcb_dependency_counter(target_bcb, &counter_kind);
debug!(
"{:?} ({:?}) gets a new Coverage statement for unclaimed counter {}",
target_bcb,
target_bb,
self.format_counter(&counter_kind),
);
target_bb
};
inject_statement(self.mir_body, counter_kind, inject_to_bb, None);
}
CoverageKind::Expression { .. } => {
inject_intermediate_expression(self.mir_body, counter_kind)
}
_ => bug!("CoverageKind should be a counter"),
}
}
}
#[inline]
fn bcb_leader_bb(&self, bcb: BasicCoverageBlock) -> BasicBlock {
self.bcb_data(bcb).leader_bb()
}
#[inline]
fn bcb_last_bb(&self, bcb: BasicCoverageBlock) -> BasicBlock {
self.bcb_data(bcb).last_bb()
}
#[inline]
fn bcb_data(&self, bcb: BasicCoverageBlock) -> &BasicCoverageBlockData {
&self.basic_coverage_blocks[bcb]
}
#[inline]
fn bcb_data_mut(&mut self, bcb: BasicCoverageBlock) -> &mut BasicCoverageBlockData {
&mut self.basic_coverage_blocks[bcb]
}
#[inline]
fn format_counter(&self, counter_kind: &CoverageKind) -> String {
self.coverage_counters.debug_counters.format_counter(counter_kind)
}
}
fn inject_edge_counter_basic_block(
mir_body: &mut mir::Body<'_>,
from_bb: BasicBlock,
to_bb: BasicBlock,
) -> BasicBlock {
let span = mir_body[from_bb].terminator().source_info.span.shrink_to_hi();
let new_bb = mir_body.basic_blocks_mut().push(BasicBlockData {
statements: vec![], // counter will be injected here
terminator: Some(Terminator {
source_info: SourceInfo::outermost(span),
kind: TerminatorKind::Goto { target: to_bb },
}),
is_cleanup: false,
});
let edge_ref = mir_body[from_bb]
.terminator_mut()
.successors_mut()
.find(|successor| **successor == to_bb)
.expect("from_bb should have a successor for to_bb");
*edge_ref = new_bb;
new_bb
}
fn inject_statement(
mir_body: &mut mir::Body<'_>,
counter_kind: CoverageKind,
bb: BasicBlock,
some_code_region: Option<CodeRegion>,
) {
debug!(
" injecting statement {:?} for {:?} at code region: {:?}",
counter_kind, bb, some_code_region
);
let data = &mut mir_body[bb];
let source_info = data.terminator().source_info;
let statement = Statement {
source_info,
kind: StatementKind::Coverage(Box::new(Coverage {
kind: counter_kind,
code_region: some_code_region,
})),
};
data.statements.insert(0, statement);
}
// Non-code expressions are injected into the coverage map, without generating executable code.
fn inject_intermediate_expression(mir_body: &mut mir::Body<'_>, expression: CoverageKind) {
debug_assert!(matches!(expression, CoverageKind::Expression { .. }));
debug!(" injecting non-code expression {:?}", expression);
let inject_in_bb = mir::START_BLOCK;
let data = &mut mir_body[inject_in_bb];
let source_info = data.terminator().source_info;
let statement = Statement {
source_info,
kind: StatementKind::Coverage(Box::new(Coverage { kind: expression, code_region: None })),
};
data.statements.push(statement);
}
/// Convert the Span into its file name, start line and column, and end line and column
fn make_code_region(
source_map: &SourceMap,
file_name: Symbol,
source_file: &Lrc<SourceFile>,
span: Span,
body_span: Span,
) -> CodeRegion {
let (start_line, mut start_col) = source_file.lookup_file_pos(span.lo());
let (end_line, end_col) = if span.hi() == span.lo() {
let (end_line, mut end_col) = (start_line, start_col);
// Extend an empty span by one character so the region will be counted.
let CharPos(char_pos) = start_col;
if span.hi() == body_span.hi() {
start_col = CharPos(char_pos - 1);
} else {
end_col = CharPos(char_pos + 1);
}
(end_line, end_col)
} else {
source_file.lookup_file_pos(span.hi())
};
let start_line = source_map.doctest_offset_line(&source_file.name, start_line);
let end_line = source_map.doctest_offset_line(&source_file.name, end_line);
CodeRegion {
file_name,
start_line: start_line as u32,
start_col: start_col.to_u32() + 1,
end_line: end_line as u32,
end_col: end_col.to_u32() + 1,
}
}
fn fn_sig_and_body<'tcx>(
tcx: TyCtxt<'tcx>,
def_id: DefId,
) -> (Option<&'tcx rustc_hir::FnSig<'tcx>>, &'tcx rustc_hir::Body<'tcx>) {
// FIXME(#79625): Consider improving MIR to provide the information needed, to avoid going back
// to HIR for it.
let hir_node = tcx.hir().get_if_local(def_id).expect("expected DefId is local");
let fn_body_id = hir::map::associated_body(hir_node).expect("HIR node is a function with body");
(hir::map::fn_sig(hir_node), tcx.hir().body(fn_body_id))
}
fn get_body_span<'tcx>(
tcx: TyCtxt<'tcx>,
hir_body: &rustc_hir::Body<'tcx>,
mir_body: &mut mir::Body<'tcx>,
) -> Span {
let mut body_span = hir_body.value.span;
let def_id = mir_body.source.def_id();
if tcx.is_closure(def_id) {
// If the MIR function is a closure, and if the closure body span
// starts from a macro, but it's content is not in that macro, try
// to find a non-macro callsite, and instrument the spans there
// instead.
loop {
let expn_data = body_span.ctxt().outer_expn_data();
if expn_data.is_root() {
break;
}
if let ExpnKind::Macro { .. } = expn_data.kind {
body_span = expn_data.call_site;
} else {
break;
}
}
}
body_span
}
fn hash_mir_source<'tcx>(tcx: TyCtxt<'tcx>, hir_body: &'tcx rustc_hir::Body<'tcx>) -> u64 {
// FIXME(cjgillot) Stop hashing HIR manually here.
let mut hcx = tcx.create_no_span_stable_hashing_context();
let mut stable_hasher = StableHasher::new();
let owner = hir_body.id().hir_id.owner;
let bodies = &tcx.hir_owner_nodes(owner).as_ref().unwrap().bodies;
hcx.with_hir_bodies(false, owner, bodies, |hcx| {
hir_body.value.hash_stable(hcx, &mut stable_hasher)
});
stable_hasher.finish()
}