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Auto merge of #77080 - richkadel:llvm-coverage-counters-2, r=tmandry

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Working branch-level code coverage

Add a generalized implementation for computing branch-level coverage spans.

This iteration resolves some of the challenges I had identified a few weeks ago.

I've tried to implement a solution that is general enough to work for a lot of different graphs/patterns. It's encouraging to see the results on fairly large and complex crates seem to meet my expectations. This may be a "functionally complete" implementation.

Except for bug fixes or edge cases I haven't run into yet, the next and essentially final step, I think, is to replace some Counters with CounterExpressions (where their counter values can be computed by adding or subtracting other counters/expressions).

Examples of branch-level coverage support enabled in this PR:

* https://github.com/richkadel/rust/blob/llvm-coverage-counters-2/src/test/run-make-fulldeps/instrument-coverage-cov-reports-base/expected_show_coverage.coverage_of_drop_trait.txt
* https://github.com/richkadel/rust/blob/llvm-coverage-counters-2/src/test/run-make-fulldeps/instrument-coverage-cov-reports-base/expected_show_coverage.coverage_of_if.txt
* https://github.com/richkadel/rust/blob/llvm-coverage-counters-2/src/test/run-make-fulldeps/instrument-coverage-cov-reports-base/expected_show_coverage.coverage_of_if_else.txt
* https://github.com/richkadel/rust/blob/llvm-coverage-counters-2/src/test/run-make-fulldeps/instrument-coverage-cov-reports-base/expected_show_coverage.coverage_of_simple_loop.txt
* https://github.com/richkadel/rust/blob/llvm-coverage-counters-2/src/test/run-make-fulldeps/instrument-coverage-cov-reports-base/expected_show_coverage.coverage_of_simple_match.txt
* ... _and others in the same directory_

Examples of coverage analysis results (MIR spanview files) used to inject counters in the right `BasicBlocks`:

* https://htmlpreview.github.io/?https://github.com/richkadel/rust/blob/llvm-coverage-counters-2/src/test/run-make-fulldeps/instrument-coverage-mir-cov-html-base/expected_mir_dump.coverage_of_drop_trait/coverage_of_drop_trait.main.-------.InstrumentCoverage.0.html
* https://htmlpreview.github.io/?https://github.com/richkadel/rust/blob/llvm-coverage-counters-2/src/test/run-make-fulldeps/instrument-coverage-mir-cov-html-base/expected_mir_dump.coverage_of_if/coverage_of_if.main.-------.InstrumentCoverage.0.html
* https://htmlpreview.github.io/?https://github.com/richkadel/rust/blob/llvm-coverage-counters-2/src/test/run-make-fulldeps/instrument-coverage-mir-cov-html-base/expected_mir_dump.coverage_of_if_else/coverage_of_if_else.main.-------.InstrumentCoverage.0.html
* https://htmlpreview.github.io/?https://github.com/richkadel/rust/blob/llvm-coverage-counters-2/src/test/run-make-fulldeps/instrument-coverage-mir-cov-html-base/expected_mir_dump.coverage_of_simple_loop/coverage_of_simple_loop.main.-------.InstrumentCoverage.0.html
* https://htmlpreview.github.io/?https://github.com/richkadel/rust/blob/llvm-coverage-counters-2/src/test/run-make-fulldeps/instrument-coverage-mir-cov-html-base/expected_mir_dump.coverage_of_simple_match/coverage_of_simple_match.main.-------.InstrumentCoverage.0.html
* ... _and others in the same directory_

Here is some sample coverage output after compiling a few real-world crates with the new branch-level coverage features:

<img width="801" alt="Screen Shot 2020-09-25 at 1 03 11 PM" src="https://user-images.githubusercontent.com/3827298/94316848-fd882c00-ff39-11ea-9cff-0402d3abd1e7.png">
<img width="721" alt="Screen Shot 2020-09-25 at 1 00 36 PM" src="https://user-images.githubusercontent.com/3827298/94316886-11cc2900-ff3a-11ea-9d03-80b26c8a5173.png">
<img width="889" alt="Screen Shot 2020-09-25 at 12 54 57 PM" src="https://user-images.githubusercontent.com/3827298/94316900-18f33700-ff3a-11ea-8a80-58f67d84b8de.png">

r? `@tmandry`
FYI: `@wesleywiser`
This commit is contained in:
bors 2020-10-05 19:34:44 +00:00
commit a1dfd2490a
151 changed files with 19004 additions and 1881 deletions
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13
compiler/rustc_codegen_ssa/src/coverageinfo/map.rs
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@ -143,7 +143,9 @@ impl FunctionCoverage {
let id_to_counter =
|new_indexes: &IndexVec<InjectedExpressionIndex, MappedExpressionIndex>,
id: ExpressionOperandId| {
if id.index() < self.counters.len() {
if id == ExpressionOperandId::ZERO {
Some(Counter::zero())
} else if id.index() < self.counters.len() {
let index = CounterValueReference::from(id.index());
self.counters
.get(index)
@ -179,14 +181,19 @@ impl FunctionCoverage {
// been assigned a `new_index`.
let mapped_expression_index =
MappedExpressionIndex::from(counter_expressions.len());
counter_expressions.push(CounterExpression::new(
let expression = CounterExpression::new(
lhs_counter,
match op {
Op::Add => ExprKind::Add,
Op::Subtract => ExprKind::Subtract,
},
rhs_counter,
));
);
debug!(
"Adding expression {:?} = {:?} at {:?}",
mapped_expression_index, expression, region
);
counter_expressions.push(expression);
new_indexes[original_index] = mapped_expression_index;
expression_regions.push((Counter::expression(mapped_expression_index), region));
}