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Remove valid_promotion_candidates

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We no longer compare the results of
`promote_consts::validate_candidates` with
`checker.promotion_candidates`, and `promote_consts` becomes the
canonical source for determining promotability.
This commit is contained in:
Dylan MacKenzie 2019-11-03 12:36:13 -08:00
parent 61a551b493
commit 328a898d23
1 changed files with 39 additions and 73 deletions
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112
src/librustc_mir/transform/qualify_consts.rs
View file

@ -1064,7 +1064,13 @@ impl<'a, 'tcx> Checker<'a, 'tcx> {
}
self.promotion_candidates.clone()
} else {
self.valid_promotion_candidates()
promote_consts::validate_candidates(
self.tcx,
self.body,
self.def_id,
&self.temp_promotion_state,
&self.unchecked_promotion_candidates,
)
};
debug!("qualify_const: promotion_candidates={:?}", promotion_candidates);
for candidate in promotion_candidates {
@ -1106,49 +1112,6 @@ impl<'a, 'tcx> Checker<'a, 'tcx> {
(qualifs.encode_to_bits(), self.tcx.arena.alloc(promoted_temps))
}
/// Get the subset of `unchecked_promotion_candidates` that are eligible
/// for promotion.
// FIXME(eddyb) replace the old candidate gathering with this.
fn valid_promotion_candidates(&self) -> Vec<Candidate> {
// Sanity-check the promotion candidates.
let candidates = promote_consts::validate_candidates(
self.tcx,
self.body,
self.def_id,
&self.temp_promotion_state,
&self.unchecked_promotion_candidates,
);
if candidates != self.promotion_candidates {
let report = |msg, candidate| {
let span = match candidate {
Candidate::Ref(loc) |
Candidate::Repeat(loc) => self.body.source_info(loc).span,
Candidate::Argument { bb, .. } => {
self.body[bb].terminator().source_info.span
}
};
self.tcx.sess.span_err(span, &format!("{}: {:?}", msg, candidate));
};
for &c in &self.promotion_candidates {
if !candidates.contains(&c) {
report("invalidated old candidate", c);
}
}
for &c in &candidates {
if !self.promotion_candidates.contains(&c) {
report("extra new candidate", c);
}
}
bug!("promotion candidate validation mismatches (see above)");
}
candidates
}
/// Returns `true` if the operand of a repeat expression is promotable.
fn should_promote_repeat_expression(&self, operand: &Operand<'tcx>) -> bool {
let not_promotable = IsNotImplicitlyPromotable::in_operand(self, operand) ||
@ -1768,39 +1731,42 @@ impl<'tcx> MirPass<'tcx> for QualifyAndPromoteConstants<'tcx> {
debug!("run_pass: mode={:?}", mode);
if let Mode::NonConstFn | Mode::ConstFn = mode {
// This is ugly because Checker holds onto mir,
// which can't be mutated until its scope ends.
let (temps, candidates) = {
let mut checker = Checker::new(tcx, def_id, body, mode);
if let Mode::ConstFn = mode {
let use_min_const_fn_checks =
!tcx.sess.opts.debugging_opts.unleash_the_miri_inside_of_you &&
tcx.is_min_const_fn(def_id);
if use_min_const_fn_checks {
// Enforce `min_const_fn` for stable `const fn`s.
use super::qualify_min_const_fn::is_min_const_fn;
if let Err((span, err)) = is_min_const_fn(tcx, def_id, body) {
error_min_const_fn_violation(tcx, span, err);
return;
}
// `check_const` should not produce any errors, but better safe than sorry
// FIXME(#53819)
// NOTE(eddyb) `check_const` is actually needed for promotion inside
// `min_const_fn` functions.
let mut checker = Checker::new(tcx, def_id, body, mode);
if let Mode::ConstFn = mode {
let use_min_const_fn_checks =
!tcx.sess.opts.debugging_opts.unleash_the_miri_inside_of_you &&
tcx.is_min_const_fn(def_id);
if use_min_const_fn_checks {
// Enforce `min_const_fn` for stable `const fn`s.
use super::qualify_min_const_fn::is_min_const_fn;
if let Err((span, err)) = is_min_const_fn(tcx, def_id, body) {
error_min_const_fn_violation(tcx, span, err);
return;
}
// Enforce a constant-like CFG for `const fn`.
checker.check_const();
} else {
while let Some((bb, data)) = checker.rpo.next() {
checker.visit_basic_block_data(bb, data);
}
// `check_const` should not produce any errors, but better safe than sorry
// FIXME(#53819)
// NOTE(eddyb) `check_const` is actually needed for promotion inside
// `min_const_fn` functions.
}
let promotion_candidates = checker.valid_promotion_candidates();
(checker.temp_promotion_state, promotion_candidates)
};
// Enforce a constant-like CFG for `const fn`.
checker.check_const();
} else {
while let Some((bb, data)) = checker.rpo.next() {
checker.visit_basic_block_data(bb, data);
}
}
// Promote only the promotable candidates.
let temps = checker.temp_promotion_state;
let candidates = promote_consts::validate_candidates(
tcx,
body,
def_id,
&temps,
&checker.unchecked_promotion_candidates,
);
// Do the actual promotion, now that we know what's viable.
self.promoted.set(