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Added a unit test for BcbCounters
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Restructured the code a little, to allow getting both the mir::Body and
coverage graph.
@richkadel
richkadel committed Nov 13, 2020
1 parent eb9f2bb commit c131063
Showing 3 changed files with 188 additions and 102 deletions.
1 change: 0 additions & 1 deletion compiler/rustc_mir/src/transform/coverage/counters.rs
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Original file line number Diff line number Diff line change
@@ -120,7 +120,6 @@ struct BcbCounters<'a> {
basic_coverage_blocks: &'a mut CoverageGraph,
}

// FIXME(richkadel): Add unit tests for `BcbCounters` functions/algorithms.
impl<'a> BcbCounters<'a> {
fn new(
coverage_counters: &'a mut CoverageCounters,
10 changes: 8 additions & 2 deletions compiler/rustc_mir/src/transform/coverage/spans.rs
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Original file line number Diff line number Diff line change
@@ -645,7 +645,10 @@ impl<'a, 'tcx> CoverageSpans<'a, 'tcx> {
}
}

fn filtered_statement_span(statement: &'a Statement<'tcx>, body_span: Span) -> Option<Span> {
pub(super) fn filtered_statement_span(
statement: &'a Statement<'tcx>,
body_span: Span,
) -> Option<Span> {
match statement.kind {
// These statements have spans that are often outside the scope of the executed source code
// for their parent `BasicBlock`.
@@ -686,7 +689,10 @@ fn filtered_statement_span(statement: &'a Statement<'tcx>, body_span: Span) -> O
}
}

fn filtered_terminator_span(terminator: &'a Terminator<'tcx>, body_span: Span) -> Option<Span> {
pub(super) fn filtered_terminator_span(
terminator: &'a Terminator<'tcx>,
body_span: Span,
) -> 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
279 changes: 180 additions & 99 deletions compiler/rustc_mir/src/transform/coverage/tests.rs
View file
Original file line number Diff line number Diff line change
@@ -1,14 +1,39 @@
//! This crate hosts a selection of "unit tests" for components of the `InstrumentCoverage` MIR
//! pass.
//!
//! The tests construct a few "mock" objects, as needed, to support the `InstrumentCoverage`
//! functions and algorithms. Mocked objects include instances of `mir::Body`; including
//! `Terminator`s of various `kind`s, and `Span` objects. Some functions used by or used on
//! real, runtime versions of these mocked-up objects have constraints (such as cross-thread
//! limitations) and deep dependencies on other elements of the full Rust compiler (which is
//! *not* constructed or mocked for these tests).
//!
//! Of particular note, attempting to simply print elements of the `mir::Body` with default
//! `Debug` formatting can fail because some `Debug` format implementations require the
//! `TyCtxt`, obtained via a static global variable that is *not* set for these tests.
//! Initializing the global type context is prohibitively complex for the scope and scale of these
//! tests (essentially requiring initializing the entire compiler).
//!
//! Also note, some basic features of `Span` also rely on the `Span`s own "session globals", which
//! are unrelated to the `TyCtxt` global. Without initializing the `Span` session globals, some
//! basic, coverage-specific features would be impossible to test, but thankfully initializing these
//! globals is comparitively simpler. The easiest way is to wrap the test in a closure argument
//! to: `rustc_span::with_default_session_globals(|| { test_here(); })`.
use super::counters;
use super::debug;
use super::graph;
use super::spans;

use coverage_test_macros::let_bcb;

use rustc_data_structures::graph::WithNumNodes;
use rustc_data_structures::graph::WithSuccessors;
use rustc_index::vec::{Idx, IndexVec};
use rustc_middle::mir::coverage::CoverageKind;
use rustc_middle::mir::*;
use rustc_middle::ty::{self, DebruijnIndex, TyS, TypeFlags};
use rustc_span::DUMMY_SP;
use rustc_span::{self, BytePos, Pos, Span, DUMMY_SP};

fn dummy_ty() -> &'static TyS<'static> {
thread_local! {
@@ -24,7 +49,6 @@ fn dummy_ty() -> &'static TyS<'static> {

struct MockBlocks<'tcx> {
blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
source_info: SourceInfo,
dummy_place: Place<'tcx>,
next_local: usize,
}
@@ -33,7 +57,6 @@ impl<'tcx> MockBlocks<'tcx> {
fn new() -> Self {
Self {
blocks: IndexVec::new(),
source_info: SourceInfo::outermost(DUMMY_SP),
dummy_place: Place { local: RETURN_PLACE, projection: ty::List::empty() },
next_local: 0,
}
@@ -45,12 +68,19 @@ impl<'tcx> MockBlocks<'tcx> {
Local::new(index)
}

fn push(&mut self, num_nops: usize, kind: TerminatorKind<'tcx>) -> BasicBlock {
let nop = Statement { source_info: self.source_info, kind: StatementKind::Nop };

fn push(&mut self, kind: TerminatorKind<'tcx>) -> BasicBlock {
let next_lo = if let Some(last) = self.blocks.last() {
self.blocks[last].terminator().source_info.span.hi()
} else {
BytePos(1)
};
let next_hi = next_lo + BytePos(1);
self.blocks.push(BasicBlockData {
statements: std::iter::repeat(&nop).cloned().take(num_nops).collect(),
terminator: Some(Terminator { source_info: self.source_info, kind }),
statements: vec![],
terminator: Some(Terminator {
source_info: SourceInfo::outermost(Span::with_root_ctxt(next_lo, next_hi)),
kind,
}),
is_cleanup: false,
})
}
@@ -75,7 +105,7 @@ impl<'tcx> MockBlocks<'tcx> {
some_from_block: Option<BasicBlock>,
to_kind: TerminatorKind<'tcx>,
) -> BasicBlock {
let new_block = self.push(1, to_kind);
let new_block = self.push(to_kind);
if let Some(from_block) = some_from_block {
self.link(from_block, new_block);
}
@@ -152,7 +182,10 @@ fn debug_basic_blocks(mir_body: &Body<'tcx>) -> String {
.basic_blocks()
.iter_enumerated()
.map(|(bb, data)| {
let kind = &data.terminator().kind;
let term = &data.terminator();
let kind = &term.kind;
let span = term.source_info.span;
let sp = format!("(span:{},{})", span.lo().to_u32(), span.hi().to_u32());
match kind {
TerminatorKind::Assert { target, .. }
| TerminatorKind::Call { destination: Some((_, target)), .. }
@@ -163,12 +196,12 @@ fn debug_basic_blocks(mir_body: &Body<'tcx>) -> String {
| TerminatorKind::Goto { target }
| TerminatorKind::InlineAsm { destination: Some(target), .. }
| TerminatorKind::Yield { resume: target, .. } => {
format!("{:?}:{} -> {:?}", bb, debug::term_type(kind), target)
format!("{}{:?}:{} -> {:?}", sp, bb, debug::term_type(kind), target)
}
TerminatorKind::SwitchInt { targets, .. } => {
format!("{:?}:{} -> {:?}", bb, debug::term_type(kind), targets)
format!("{}{:?}:{} -> {:?}", sp, bb, debug::term_type(kind), targets)
}
_ => format!("{:?}:{}", bb, debug::term_type(kind)),
_ => format!("{}{:?}:{}", sp, bb, debug::term_type(kind)),
}
})
.collect::<Vec<_>>()
@@ -235,7 +268,7 @@ fn print_coverage_graphviz(
}

/// Create a mock `Body` with a simple flow.
fn mir_goto_switchint() -> Body<'a> {
fn goto_switchint() -> Body<'a> {
let mut blocks = MockBlocks::new();
let start = blocks.call(None);
let goto = blocks.goto(Some(start));
@@ -281,13 +314,22 @@ fn mir_goto_switchint() -> Body<'a> {
mir_body
}

fn covgraph_goto_switchint() -> graph::CoverageGraph {
let mir_body = mir_goto_switchint();
macro_rules! assert_successors {
($basic_coverage_blocks:ident, $i:ident, [$($successor:ident),*]) => {
let mut successors = $basic_coverage_blocks.successors[$i].clone();
successors.sort_unstable();
assert_eq!(successors, vec![$($successor),*]);
}
}

#[test]
fn test_covgraph_goto_switchint() {
let mir_body = goto_switchint();
if false {
println!("basic_blocks = {}", debug_basic_blocks(&mir_body));
}
let covgraph = graph::CoverageGraph::from_mir(&mir_body);
print_coverage_graphviz("covgraph_goto_switchint ", &mir_body, &covgraph);
let basic_coverage_blocks = graph::CoverageGraph::from_mir(&mir_body);
print_coverage_graphviz("covgraph_goto_switchint ", &mir_body, &basic_coverage_blocks);
/*
┌──────────────┐ ┌─────────────────┐
│ bcb2: Return │ ◀── │ bcb0: SwitchInt │
@@ -299,11 +341,24 @@ fn covgraph_goto_switchint() -> graph::CoverageGraph {
│ bcb1: Return │
└─────────────────┘
*/
covgraph
assert_eq!(
basic_coverage_blocks.num_nodes(),
3,
"basic_coverage_blocks: {:?}",
basic_coverage_blocks.iter_enumerated().collect::<Vec<_>>()
);

let_bcb!(0);
let_bcb!(1);
let_bcb!(2);

assert_successors!(basic_coverage_blocks, bcb0, [bcb1, bcb2]);
assert_successors!(basic_coverage_blocks, bcb1, []);
assert_successors!(basic_coverage_blocks, bcb2, []);
}

/// Create a mock `Body` with a loop.
fn mir_switchint_then_loop_else_return() -> Body<'a> {
fn switchint_then_loop_else_return() -> Body<'a> {
let mut blocks = MockBlocks::new();
let start = blocks.call(None);
let switchint = blocks.switchint(Some(start));
@@ -342,10 +397,15 @@ fn mir_switchint_then_loop_else_return() -> Body<'a> {
mir_body
}

fn covgraph_switchint_then_loop_else_return() -> graph::CoverageGraph {
let mir_body = mir_switchint_then_loop_else_return();
let covgraph = graph::CoverageGraph::from_mir(&mir_body);
print_coverage_graphviz("covgraph_switchint_then_loop_else_return", &mir_body, &covgraph);
#[test]
fn test_covgraph_switchint_then_loop_else_return() {
let mir_body = switchint_then_loop_else_return();
let basic_coverage_blocks = graph::CoverageGraph::from_mir(&mir_body);
print_coverage_graphviz(
"covgraph_switchint_then_loop_else_return",
&mir_body,
&basic_coverage_blocks,
);
/*
┌─────────────────┐
│ bcb0: Call │
@@ -365,11 +425,26 @@ fn covgraph_switchint_then_loop_else_return() -> graph::CoverageGraph {
│ │
└─────────────────────────────────────┘
*/
covgraph
assert_eq!(
basic_coverage_blocks.num_nodes(),
4,
"basic_coverage_blocks: {:?}",
basic_coverage_blocks.iter_enumerated().collect::<Vec<_>>()
);

let_bcb!(0);
let_bcb!(1);
let_bcb!(2);
let_bcb!(3);

assert_successors!(basic_coverage_blocks, bcb0, [bcb1]);
assert_successors!(basic_coverage_blocks, bcb1, [bcb2, bcb3]);
assert_successors!(basic_coverage_blocks, bcb2, []);
assert_successors!(basic_coverage_blocks, bcb3, [bcb1]);
}

/// Create a mock `Body` with nested loops.
fn mir_switchint_loop_then_inner_loop_else_break() -> Body<'a> {
fn switchint_loop_then_inner_loop_else_break() -> Body<'a> {
let mut blocks = MockBlocks::new();
let start = blocks.call(None);
let switchint = blocks.switchint(Some(start));
@@ -438,13 +513,14 @@ fn mir_switchint_loop_then_inner_loop_else_break() -> Body<'a> {
mir_body
}

fn covgraph_switchint_loop_then_inner_loop_else_break() -> graph::CoverageGraph {
let mir_body = mir_switchint_loop_then_inner_loop_else_break();
let covgraph = graph::CoverageGraph::from_mir(&mir_body);
#[test]
fn test_covgraph_switchint_loop_then_inner_loop_else_break() {
let mir_body = switchint_loop_then_inner_loop_else_break();
let basic_coverage_blocks = graph::CoverageGraph::from_mir(&mir_body);
print_coverage_graphviz(
"covgraph_switchint_loop_then_inner_loop_else_break",
&mir_body,
&covgraph,
&basic_coverage_blocks,
);
/*
┌─────────────────┐
@@ -477,39 +553,34 @@ fn covgraph_switchint_loop_then_inner_loop_else_break() -> graph::CoverageGraph
│ │
└────────────────────────────────────────────┘
*/
covgraph
}

macro_rules! assert_successors {
($basic_coverage_blocks:ident, $i:ident, [$($successor:ident),*]) => {
let mut successors = $basic_coverage_blocks.successors[$i].clone();
successors.sort_unstable();
assert_eq!(successors, vec![$($successor),*]);
}
}

#[test]
fn test_covgraph_goto_switchint() {
let basic_coverage_blocks = covgraph_goto_switchint();
assert_eq!(
basic_coverage_blocks.num_nodes(),
3,
7,
"basic_coverage_blocks: {:?}",
basic_coverage_blocks.iter_enumerated().collect::<Vec<_>>()
);

let_bcb!(0);
let_bcb!(1);
let_bcb!(2);
let_bcb!(3);
let_bcb!(4);
let_bcb!(5);
let_bcb!(6);

assert_successors!(basic_coverage_blocks, bcb0, [bcb1, bcb2]);
assert_successors!(basic_coverage_blocks, bcb1, []);
assert_successors!(basic_coverage_blocks, bcb0, [bcb1]);
assert_successors!(basic_coverage_blocks, bcb1, [bcb2, bcb3]);
assert_successors!(basic_coverage_blocks, bcb2, []);
assert_successors!(basic_coverage_blocks, bcb3, [bcb4]);
assert_successors!(basic_coverage_blocks, bcb4, [bcb5, bcb6]);
assert_successors!(basic_coverage_blocks, bcb5, [bcb1]);
assert_successors!(basic_coverage_blocks, bcb6, [bcb4]);
}

#[test]
fn test_find_loop_backedges_none() {
let basic_coverage_blocks = covgraph_goto_switchint();
let mir_body = goto_switchint();
let basic_coverage_blocks = graph::CoverageGraph::from_mir(&mir_body);
if false {
println!(
"basic_coverage_blocks = {:?}",
@@ -526,30 +597,10 @@ fn test_find_loop_backedges_none() {
);
}

#[test]
fn test_covgraph_switchint_then_loop_else_return() {
let basic_coverage_blocks = covgraph_switchint_then_loop_else_return();
assert_eq!(
basic_coverage_blocks.num_nodes(),
4,
"basic_coverage_blocks: {:?}",
basic_coverage_blocks.iter_enumerated().collect::<Vec<_>>()
);

let_bcb!(0);
let_bcb!(1);
let_bcb!(2);
let_bcb!(3);

assert_successors!(basic_coverage_blocks, bcb0, [bcb1]);
assert_successors!(basic_coverage_blocks, bcb1, [bcb2, bcb3]);
assert_successors!(basic_coverage_blocks, bcb2, []);
assert_successors!(basic_coverage_blocks, bcb3, [bcb1]);
}

#[test]
fn test_find_loop_backedges_one() {
let basic_coverage_blocks = covgraph_switchint_then_loop_else_return();
let mir_body = switchint_then_loop_else_return();
let basic_coverage_blocks = graph::CoverageGraph::from_mir(&mir_body);
let backedges = graph::find_loop_backedges(&basic_coverage_blocks);
assert_eq!(
backedges.iter_enumerated().map(|(_bcb, backedges)| backedges.len()).sum::<usize>(),
@@ -564,36 +615,10 @@ fn test_find_loop_backedges_one() {
assert_eq!(backedges[bcb1], vec![bcb3]);
}

#[test]
fn test_covgraph_switchint_loop_then_inner_loop_else_break() {
let basic_coverage_blocks = covgraph_switchint_loop_then_inner_loop_else_break();
assert_eq!(
basic_coverage_blocks.num_nodes(),
7,
"basic_coverage_blocks: {:?}",
basic_coverage_blocks.iter_enumerated().collect::<Vec<_>>()
);

let_bcb!(0);
let_bcb!(1);
let_bcb!(2);
let_bcb!(3);
let_bcb!(4);
let_bcb!(5);
let_bcb!(6);

assert_successors!(basic_coverage_blocks, bcb0, [bcb1]);
assert_successors!(basic_coverage_blocks, bcb1, [bcb2, bcb3]);
assert_successors!(basic_coverage_blocks, bcb2, []);
assert_successors!(basic_coverage_blocks, bcb3, [bcb4]);
assert_successors!(basic_coverage_blocks, bcb4, [bcb5, bcb6]);
assert_successors!(basic_coverage_blocks, bcb5, [bcb1]);
assert_successors!(basic_coverage_blocks, bcb6, [bcb4]);
}

#[test]
fn test_find_loop_backedges_two() {
let basic_coverage_blocks = covgraph_switchint_loop_then_inner_loop_else_break();
let mir_body = switchint_loop_then_inner_loop_else_break();
let basic_coverage_blocks = graph::CoverageGraph::from_mir(&mir_body);
let backedges = graph::find_loop_backedges(&basic_coverage_blocks);
assert_eq!(
backedges.iter_enumerated().map(|(_bcb, backedges)| backedges.len()).sum::<usize>(),
@@ -613,7 +638,8 @@ fn test_find_loop_backedges_two() {

#[test]
fn test_traverse_coverage_with_loops() {
let basic_coverage_blocks = covgraph_switchint_loop_then_inner_loop_else_break();
let mir_body = switchint_loop_then_inner_loop_else_break();
let basic_coverage_blocks = graph::CoverageGraph::from_mir(&mir_body);
let mut traversed_in_order = Vec::new();
let mut traversal = graph::TraverseCoverageGraphWithLoops::new(&basic_coverage_blocks);
while let Some(bcb) = traversal.next(&basic_coverage_blocks) {
@@ -630,3 +656,58 @@ fn test_traverse_coverage_with_loops() {
"bcb6 should not be visited until all nodes inside the first loop have been visited"
);
}

fn synthesize_body_span_from_terminators(mir_body: &Body<'_>) -> Span {
let mut some_span: Option<Span> = None;
for (_, data) in mir_body.basic_blocks().iter_enumerated() {
let term_span = data.terminator().source_info.span;
if let Some(span) = some_span.as_mut() {
*span = span.to(term_span);
} else {
some_span = Some(term_span)
}
}
some_span.expect("body must have at least one BasicBlock")
}

#[test]
fn test_make_bcb_counters() {
rustc_span::with_default_session_globals(|| {
let mir_body = goto_switchint();
let body_span = synthesize_body_span_from_terminators(&mir_body);
let mut basic_coverage_blocks = graph::CoverageGraph::from_mir(&mir_body);
let mut coverage_spans = Vec::new();
for (bcb, data) in basic_coverage_blocks.iter_enumerated() {
if let Some(span) =
spans::filtered_terminator_span(data.terminator(&mir_body), body_span)
{
coverage_spans.push(spans::CoverageSpan::for_terminator(span, bcb, data.last_bb()));
}
}
let mut coverage_counters = counters::CoverageCounters::new(0);
let intermediate_expressions = coverage_counters
.make_bcb_counters(&mut basic_coverage_blocks, &coverage_spans)
.expect("should be Ok");
assert_eq!(intermediate_expressions.len(), 0);

let_bcb!(1);
assert_eq!(
1, // coincidentally, bcb1 has a `Counter` with id = 1
match basic_coverage_blocks[bcb1].counter().expect("should have a counter") {
CoverageKind::Counter { id, .. } => id,
_ => panic!("expected a Counter"),
}
.as_u32()
);

let_bcb!(2);
assert_eq!(
2, // coincidentally, bcb2 has a `Counter` with id = 2
match basic_coverage_blocks[bcb2].counter().expect("should have a counter") {
CoverageKind::Counter { id, .. } => id,
_ => panic!("expected a Counter"),
}
.as_u32()
);
});
}

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