Struct rustc_mir::transform::coverage::counters::BcbCounters

pub(in transform::coverage::counters) struct BcbCounters<'a> {
    coverage_counters: &'a mut CoverageCounters,
    basic_coverage_blocks: &'a mut CoverageGraph,
}

Traverse the CoverageGraph and add either a Counter or Expression to every BCB, to be injected with CoverageSpans. 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 mut CoverageGraph

Implementations

impl<'a> BcbCounters<'a>

pub(in transform::coverage::counters) fn new(
    coverage_counters: &'a mut CoverageCounters,
    basic_coverage_blocks: &'a mut CoverageGraph
) -> Self

pub(in transform::coverage::counters) fn make_bcb_counters(
    &mut self,
    coverage_spans: &Vec<CoverageSpan>
) -> Result<Vec<CoverageKind>, Error>

If two BasicCoverageBlocks 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.

Returns any non-code-span expressions created to represent intermediate values (such as to add two counters so the result can be subtracted from another counter), or an Error with message for subsequent debugging.

pub(in transform::coverage::counters) fn make_branch_counters(
    &mut self,
    traversal: &mut TraverseCoverageGraphWithLoops,
    branching_bcb: BasicCoverageBlock,
    branching_counter_operand: ExpressionOperandId,
    collect_intermediate_expressions: &mut Vec<CoverageKind>
) -> Result<(), Error>

pub(in transform::coverage::counters) fn get_or_make_counter_operand(
    &mut self,
    bcb: BasicCoverageBlock,
    collect_intermediate_expressions: &mut Vec<CoverageKind>
) -> Result<ExpressionOperandId, Error>

pub(in transform::coverage::counters) fn recursive_get_or_make_counter_operand(
    &mut self,
    bcb: BasicCoverageBlock,
    collect_intermediate_expressions: &mut Vec<CoverageKind>,
    debug_indent_level: usize
) -> Result<ExpressionOperandId, Error>

pub(in transform::coverage::counters) fn get_or_make_edge_counter_operand(
    &mut self,
    from_bcb: BasicCoverageBlock,
    to_bcb: BasicCoverageBlock,
    collect_intermediate_expressions: &mut Vec<CoverageKind>
) -> Result<ExpressionOperandId, Error>

pub(in transform::coverage::counters) fn recursive_get_or_make_edge_counter_operand(
    &mut self,
    from_bcb: BasicCoverageBlock,
    to_bcb: BasicCoverageBlock,
    collect_intermediate_expressions: &mut Vec<CoverageKind>,
    debug_indent_level: usize
) -> Result<ExpressionOperandId, Error>

pub(in transform::coverage::counters) fn choose_preferred_expression_branch(
    &self,
    traversal: &TraverseCoverageGraphWithLoops,
    branches: &Vec<BcbBranch>
) -> BcbBranch

Select a branch for the expression, either the recommended reloop_branch, or if none was found, select any branch.

pub(in transform::coverage::counters) fn find_some_reloop_branch(
    &self,
    traversal: &TraverseCoverageGraphWithLoops,
    branches: &Vec<BcbBranch>
) -> Option<BcbBranch>

At most, one of the branches (or its edge, from the branching_bcb, if the branch has multiple incoming edges) can have a counter computed by expression.

If at least one of the branches leads outside of a loop (found_loop_exit is true), and at least one other branch does not exit the loop (the first of which is captured in some_reloop_branch), it's likely any reloop branch will be executed far more often than loop exit branch, making the reloop branch a better candidate for an expression.

pub(in transform::coverage::counters) fn bcb_predecessors(
    &self,
    bcb: BasicCoverageBlock
) -> &Vec<BasicCoverageBlock>

pub(in transform::coverage::counters) fn bcb_successors(
    &self,
    bcb: BasicCoverageBlock
) -> &Vec<BasicCoverageBlock>

pub(in transform::coverage::counters) fn bcb_branches(
    &self,
    from_bcb: BasicCoverageBlock
) -> Vec<BcbBranch>

pub(in transform::coverage::counters) fn bcb_needs_branch_counters(
    &self,
    bcb: BasicCoverageBlock
) -> bool

pub(in transform::coverage::counters) fn bcb_has_one_path_to_target(
    &self,
    bcb: BasicCoverageBlock
) -> bool

Returns true if the BasicCoverageBlock has zero or one incoming edge. (If zero, it should be the entry point for the function.)

pub(in transform::coverage::counters) fn bcb_is_dominated_by(
    &self,
    node: BasicCoverageBlock,
    dom: BasicCoverageBlock
) -> bool

pub(in transform::coverage::counters) fn format_counter(
    &self,
    counter_kind: &CoverageKind
) -> String