bjoernager/rust
bjoernager/rust
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This commit is contained in:
Rich Kadel 2020-10-25 11:13:16 -07:00
parent 5545c56e9d
commit 1973f84ebb
8 changed files with 41 additions and 57 deletions
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20
compiler/rustc_mir/src/transform/coverage/query.rs
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@ -1,3 +1,5 @@
use super::counters;
use rustc_middle::mir::coverage::*;
use rustc_middle::mir::visit::Visitor;
use rustc_middle::mir::{Coverage, CoverageInfo, Location};
@ -32,21 +34,16 @@ pub(crate) fn provide(providers: &mut Providers) {
/// safeguard, with `add_missing_operands` set to `true`, to find any other counter or expression
/// IDs referenced by expression operands, if not already seen.
///
/// Ideally, every expression operand in the MIR will have a corresponding Counter or Expression,
/// but since current or future MIR optimizations can theoretically optimize out segments of a
/// MIR, it may not be possible to guarantee this, so the second pass ensures the `CoverageInfo`
/// counts include all referenced IDs.
/// Ideally, each operand ID in a MIR `CoverageKind::Expression` will have a separate MIR `Coverage`
/// statement for the `Counter` or `Expression` with the referenced ID. but since current or future
/// MIR optimizations can theoretically optimize out segments of a MIR, it may not be possible to
/// guarantee this, so the second pass ensures the `CoverageInfo` counts include all referenced IDs.
struct CoverageVisitor {
info: CoverageInfo,
add_missing_operands: bool,
}
impl CoverageVisitor {
// If an expression operand is encountered with an ID outside the range of known counters and
// expressions, 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.
const MAX_COUNTER_GUARD: u32 = (u32::MAX / 2) + 1;
#[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);
@ -62,7 +59,10 @@ 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 <= Self::MAX_COUNTER_GUARD {
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.
self.update_num_counters(operand_id)
} else {
self.update_num_expressions(operand_id)