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coverage: Migrate branch coverage to use CoveragePoint and HIR analysis #162425

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coverage: Migrate branch coverage to use CoveragePoint and HIR analysis #162425

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2 changes: 1 addition & 1 deletion compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -111,7 +111,7 @@ impl<'tcx> CoverageInfoBuilderMethods<'tcx> for Builder<'_, '_, 'tcx> {
};

match *kind {
CoverageKind::Point { .. } | CoverageKind::BlockMarker { .. } => unreachable!(
CoverageKind::Point { .. } => unreachable!(
"marker statement {kind:?} should have been removed by CleanupPostBorrowck"
),
CoverageKind::VirtualCounter { bcb }
Expand Down
54 changes: 11 additions & 43 deletions compiler/rustc_middle/src/mir/coverage.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,15 +8,6 @@ use rustc_index::{Idx, IndexVec};
use rustc_macros::{StableHash, TyDecodable, TyEncodable};
use rustc_span::Span;

rustc_index::newtype_index! {
/// Used by [`CoverageKind::BlockMarker`] to mark blocks during THIR-to-MIR
/// lowering, so that those blocks can be identified later.
#[stable_hash]
#[encodable]
#[debug_format = "BlockMarkerId({})"]
pub struct BlockMarkerId {}
}

rustc_index::newtype_index! {
/// ID of a coverage counter. Values ascend from 0.
///
Expand Down Expand Up @@ -76,11 +67,21 @@ impl Debug for CovTerm {
pub enum PointKind {
/// Inserted just before evaluating an expression.
Expr,

/// Inserted when a one-sided `if` expression generates its synthetic `else {}`.
/// The absent `else` has no node, so [`HirId`] is the `if` expression.
ImplicitElse,

/// Inserted at the end of a function's body. [`HirId`] is the function itself.
FunctionEnd,

/// Inserted into the true-outcome and false-outcome blocks after branching on
/// a boolean condition or a fallible `let`.
///
/// [`HirId`] is one of:
/// - The boolean expression being tested
/// - The initializer expression (RHS) of a fallible `let`
BranchOutcome { outcome: bool },
}

#[derive(Clone, PartialEq, TyEncodable, TyDecodable, StableHash)]
Expand All @@ -90,12 +91,6 @@ pub enum CoverageKind {
/// indicated by [`PointKind`]. Injected during MIR building.
Point { point_kind: PointKind, hir_id: HirId },

/// Marks its enclosing basic block with an ID that can be referred to by
/// side data in [`CoverageEarlyInfo`].
///
/// Should be erased before codegen (at some point after `InstrumentCoverage`).
BlockMarker { id: BlockMarkerId },

/// Marks its enclosing basic block with the ID of the coverage graph node
/// that it was part of during the `InstrumentCoverage` MIR pass.
///
Expand All @@ -110,7 +105,6 @@ impl Debug for CoverageKind {
CoverageKind::Point { point_kind, hir_id } => {
write!(fmt, "Point({point_kind:?}, {hir_id:?}")
}
CoverageKind::BlockMarker { id } => write!(fmt, "BlockMarker({:?})", id.index()),
CoverageKind::VirtualCounter { bcb } => write!(fmt, "VirtualCounter({bcb:?})"),
}
}
Expand All @@ -122,7 +116,7 @@ impl CoverageKind {
/// no longer needed after that pass.
pub fn is_removed_after_analysis(&self) -> bool {
match self {
CoverageKind::Point { .. } | CoverageKind::BlockMarker { .. } => true,
CoverageKind::Point { .. } => true,
CoverageKind::VirtualCounter { .. } => false,
}
}
Expand Down Expand Up @@ -184,32 +178,6 @@ pub struct CoverageMirInfo {
pub mappings: Vec<Mapping>,
}

/// Coverage information for a function, collected in advance at the THIR/MIR
/// boundary during MIR building, and attached to the corresponding `mir::Body`.
///
/// This side-data is "early" in that it must be collected prior to the main
/// instrumentation step, in contrast to the main [`CoverageMirInfo`] produced
/// by instrumentation itself.
///
/// Used by the `InstrumentCoverage` MIR pass.
#[derive(Clone, Debug)]
#[derive(TyEncodable, TyDecodable, Hash, StableHash)]
pub struct CoverageEarlyInfo {
/// 1 more than the highest-numbered [`CoverageKind::BlockMarker`] that was
/// injected into the MIR body. This makes it possible to allocate per-ID
/// data structures without having to scan the entire body first.
pub num_block_markers: usize,
pub branch_spans: Vec<BranchSpan>,
}

#[derive(Clone, Debug)]
#[derive(TyEncodable, TyDecodable, Hash, StableHash)]
pub struct BranchSpan {
pub span: Span,
pub true_marker: BlockMarkerId,
pub false_marker: BlockMarkerId,
}

/// Contains information needed during codegen, obtained by inspecting the
/// function's MIR after MIR optimizations.
///
Expand Down
11 changes: 0 additions & 11 deletions compiler/rustc_middle/src/mir/mod.rs
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Expand Up @@ -310,15 +310,6 @@ pub struct Body<'tcx> {

pub tainted_by_errors: Option<ErrorGuaranteed>,

/// Coverage information collected at the THIR/MIR boundary during MIR
/// building, to be used by the `InstrumentCoverage` pass.
///
/// Only present if coverage is enabled and this function is eligible.
/// Boxed to limit space overhead in non-coverage builds.
#[type_foldable(identity)]
#[type_visitable(ignore)]
pub coverage_early_info: Option<Box<coverage::CoverageEarlyInfo>>,

/// Per-function coverage information added by the `InstrumentCoverage`
/// pass, to be used in conjunction with the coverage statements injected
/// into this body's blocks.
Expand Down Expand Up @@ -369,7 +360,6 @@ impl<'tcx> Body<'tcx> {
is_polymorphic: false,
injection_phase: None,
tainted_by_errors,
coverage_early_info: None,
coverage_mir_info: None,
};
body.is_polymorphic = body.has_non_region_param();
Expand Down Expand Up @@ -400,7 +390,6 @@ impl<'tcx> Body<'tcx> {
is_polymorphic: false,
injection_phase: None,
tainted_by_errors: None,
coverage_early_info: None,
coverage_mir_info: None,
};
body.is_polymorphic = body.has_non_region_param();
Expand Down
27 changes: 0 additions & 27 deletions compiler/rustc_middle/src/mir/pretty.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -630,40 +630,13 @@ fn write_mir_intro<'tcx>(
// Add an empty line before the first block is printed.
writeln!(w)?;

if let Some(early_info) = &body.coverage_early_info {
write_coverage_early_info(early_info, w)?;
}
if let Some(mir_info) = &body.coverage_mir_info {
write_coverage_mir_info(mir_info, w)?;
}

Ok(())
}

fn write_coverage_early_info(
early_info: &coverage::CoverageEarlyInfo,
w: &mut dyn io::Write,
) -> io::Result<()> {
let coverage::CoverageEarlyInfo { num_block_markers: _, branch_spans } = early_info;

// Only add an extra trailing newline if we printed at least one thing.
let mut did_print = false;

for coverage::BranchSpan { span, true_marker, false_marker } in branch_spans {
writeln!(
w,
"{INDENT}coverage branch {{ true: {true_marker:?}, false: {false_marker:?} }} => {span:?}",
)?;
did_print = true;
}

if did_print {
writeln!(w)?;
}

Ok(())
}

fn write_coverage_mir_info(
mir_info: &coverage::CoverageMirInfo,
w: &mut dyn io::Write,
Expand Down
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