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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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19
compiler/rustc_middle/src/mir/coverage/mod.rs
View file

@ -14,6 +14,20 @@ rustc_index::newtype_index! {
}
}
impl ExpressionOperandId {
/// An expression operand for a "zero counter", as described in the following references:
///
/// * https://github.com/rust-lang/llvm-project/blob/llvmorg-8.0.0/llvm/docs/CoverageMappingFormat.rst#counter
/// * https://github.com/rust-lang/llvm-project/blob/llvmorg-8.0.0/llvm/docs/CoverageMappingFormat.rst#tag
/// * https://github.com/rust-lang/llvm-project/blob/llvmorg-8.0.0/llvm/docs/CoverageMappingFormat.rst#counter-expressions
///
/// This operand can be used to count two or more separate code regions with a single counter,
/// if they run sequentially with no branches, by injecting the `Counter` in a `BasicBlock` for
/// one of the code regions, and inserting `CounterExpression`s ("add ZERO to the counter") in
/// the coverage map for the other code regions.
pub const ZERO: Self = Self::from_u32(0);
}
rustc_index::newtype_index! {
pub struct CounterValueReference {
derive [HashStable]
@ -22,6 +36,11 @@ rustc_index::newtype_index! {
}
}
impl CounterValueReference {
// Counters start at 1 to reserve 0 for ExpressionOperandId::ZERO.
pub const START: Self = Self::from_u32(1);
}
rustc_index::newtype_index! {
pub struct InjectedExpressionIndex {
derive [HashStable]

2
compiler/rustc_middle/src/mir/visit.rs
View file

@ -752,7 +752,7 @@ macro_rules! make_mir_visitor {
}
fn super_coverage(&mut self,
_kind: & $($mutability)? Coverage,
_coverage: & $($mutability)? Coverage,
_location: Location) {
}