Struct rustc_mir_transform::coverage::counters::MakeBcbCounters
source · struct MakeBcbCounters<'a> {
coverage_counters: &'a mut CoverageCounters,
basic_coverage_blocks: &'a CoverageGraph,
}
Expand description
Traverse the CoverageGraph
and add either a Counter
or Expression
to every BCB, to be
injected with coverage spans. Expressions
have no runtime overhead, so if a viable expression
(adding or subtracting two other counters or expressions) can compute the same result as an
embedded counter, an Expression
should be used.
Fields§
§coverage_counters: &'a mut CoverageCounters
§basic_coverage_blocks: &'a CoverageGraph
Implementations§
source§impl<'a> MakeBcbCounters<'a>
impl<'a> MakeBcbCounters<'a>
fn new( coverage_counters: &'a mut CoverageCounters, basic_coverage_blocks: &'a CoverageGraph, ) -> Self
sourcefn make_bcb_counters(
&mut self,
bcb_has_coverage_spans: impl Fn(BasicCoverageBlock) -> bool,
)
fn make_bcb_counters( &mut self, bcb_has_coverage_spans: impl Fn(BasicCoverageBlock) -> bool, )
If two BasicCoverageBlock
s branch from another BasicCoverageBlock
, one of the branches
can be counted by Expression
by subtracting the other branch from the branching
block. Otherwise, the BasicCoverageBlock
executed the least should have the Counter
.
One way to predict which branch executes the least is by considering loops. A loop is exited
at a branch, so the branch that jumps to a BasicCoverageBlock
outside the loop is almost
always executed less than the branch that does not exit the loop.
fn make_node_and_branch_counters( &mut self, traversal: &TraverseCoverageGraphWithLoops<'_>, from_bcb: BasicCoverageBlock, )
fn get_or_make_counter_operand(&mut self, bcb: BasicCoverageBlock) -> BcbCounter
fn get_or_make_edge_counter_operand( &mut self, from_bcb: BasicCoverageBlock, to_bcb: BasicCoverageBlock, ) -> BcbCounter
sourcefn choose_preferred_expression_branch(
&self,
traversal: &TraverseCoverageGraphWithLoops<'_>,
from_bcb: BasicCoverageBlock,
) -> BasicCoverageBlock
fn choose_preferred_expression_branch( &self, traversal: &TraverseCoverageGraphWithLoops<'_>, from_bcb: BasicCoverageBlock, ) -> BasicCoverageBlock
Select a branch for the expression, either the recommended reloop_branch
, or if none was
found, select any branch.
sourcefn find_good_reloop_branch(
&self,
traversal: &TraverseCoverageGraphWithLoops<'_>,
from_bcb: BasicCoverageBlock,
) -> Option<BasicCoverageBlock>
fn find_good_reloop_branch( &self, traversal: &TraverseCoverageGraphWithLoops<'_>, from_bcb: BasicCoverageBlock, ) -> Option<BasicCoverageBlock>
Tries to find a branch that leads back to the top of a loop, and that doesn’t already have a counter. Such branches are good candidates to be given an expression (instead of a physical counter), because they will tend to be executed more times than a loop-exit branch.
fn bcb_predecessors(&self, bcb: BasicCoverageBlock) -> &[BasicCoverageBlock]
fn bcb_successors(&self, bcb: BasicCoverageBlock) -> &[BasicCoverageBlock]
fn branch_has_no_counter( &self, from_bcb: BasicCoverageBlock, to_bcb: BasicCoverageBlock, ) -> bool
fn branch_counter( &self, from_bcb: BasicCoverageBlock, to_bcb: BasicCoverageBlock, ) -> Option<&BcbCounter>
Auto Trait Implementations§
impl<'a> Freeze for MakeBcbCounters<'a>
impl<'a> RefUnwindSafe for MakeBcbCounters<'a>
impl<'a> Send for MakeBcbCounters<'a>
impl<'a> Sync for MakeBcbCounters<'a>
impl<'a> Unpin for MakeBcbCounters<'a>
impl<'a> !UnwindSafe for MakeBcbCounters<'a>
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Size: 16 bytes