bjoernager/rust
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Responded to all feedback as of 2020-10-30

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This commit is contained in:
Rich Kadel 2020-10-30 16:09:05 -07:00
parent 1973f84ebb
commit a7d956583c
9 changed files with 367 additions and 208 deletions
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26
compiler/rustc_mir/src/transform/coverage/query.rs
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@ -1,5 +1,3 @@
use super::counters;
use rustc_middle::mir::coverage::*;
use rustc_middle::mir::visit::Visitor;
use rustc_middle::mir::{Coverage, CoverageInfo, Location};
@ -44,11 +42,16 @@ struct CoverageVisitor {
}
impl CoverageVisitor {
/// Updates `num_counters` to the maximum encountered zero-based counter_id plus 1. Note the
/// final computed number of counters should be the number of all `CoverageKind::Counter`
/// statements in the MIR *plus one* for the implicit `ZERO` counter.
#[inline(always)]
fn update_num_counters(&mut self, counter_id: u32) {
self.info.num_counters = std::cmp::max(self.info.num_counters, counter_id + 1);
}
/// Computes an expression index for each expression ID, and updates `num_expressions` to the
/// maximum encountered index plus 1.
#[inline(always)]
fn update_num_expressions(&mut self, expression_id: u32) {
let expression_index = u32::MAX - expression_id;
@ -59,10 +62,18 @@ impl CoverageVisitor {
if operand_id >= self.info.num_counters {
let operand_as_expression_index = u32::MAX - operand_id;
if operand_as_expression_index >= self.info.num_expressions {
if operand_id <= counters::MAX_COUNTER_GUARD {
// Since the complete range of counter and expression IDs is not known here, the
// only way to determine if the ID is a counter ID or an expression ID is to
// assume a maximum possible counter ID value.
// The operand ID is outside the known range of counter IDs and also outside the
// known range of expression IDs. In either case, the result of a missing operand
// (if and when used in an expression) will be zero, so from a computation
// perspective, it doesn't matter whether it is interepretted as a counter or an
// expression.
//
// However, the `num_counters` and `num_expressions` query results are used to
// allocate arrays when generating the coverage map (during codegen), so choose
// the type that grows either `num_counters` or `num_expressions` the least.
if operand_id - self.info.num_counters
< operand_as_expression_index - self.info.num_expressions
{
self.update_num_counters(operand_id)
} else {
self.update_num_expressions(operand_id)
@ -100,7 +111,8 @@ fn coverageinfo_from_mir<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> CoverageInfo
let mir_body = tcx.optimized_mir(def_id);
let mut coverage_visitor = CoverageVisitor {
info: CoverageInfo { num_counters: 0, num_expressions: 0 },
// num_counters always has at least the `ZERO` counter.
info: CoverageInfo { num_counters: 1, num_expressions: 0 },
add_missing_operands: false,
};