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avoid duplicating StorageLive in let-else

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This commit is contained in:
Ding Xiang Fei 2022-09-16 19:02:45 +08:00
parent bc7b17cfe3
commit 48c1c1d190
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GPG Key ID: 3CD748647EEF6359
2 changed files with 33 additions and 9 deletions
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3
compiler/rustc_mir_build/src/build/block.rs
View File

@ -232,7 +232,8 @@ fn ast_block_stmts(
pattern,
UserTypeProjections::none(),
&mut |this, _, _, _, node, span, _, _| {
this.storage_live_binding(block, node, span, OutsideGuard, false);
this.storage_live_binding(block, node, span, OutsideGuard, true);
this.schedule_drop_for_binding(node, span, OutsideGuard);
},
);
let failure = unpack!(

29
compiler/rustc_mir_build/src/build/matches/mod.rs
View File

@ -371,6 +371,7 @@ fn lower_match_arms(
Some(arm.span),
Some(arm.scope),
Some(match_scope),
false,
);
if let Some(source_scope) = scope {
@ -416,6 +417,7 @@ fn bind_pattern(
arm_span: Option<Span>,
arm_scope: Option<region::Scope>,
match_scope: Option<region::Scope>,
storages_alive: bool,
) -> BasicBlock {
if candidate.subcandidates.is_empty() {
// Avoid generating another `BasicBlock` when we only have one
@ -429,6 +431,7 @@ fn bind_pattern(
arm_span,
match_scope,
true,
storages_alive,
)
} else {
// It's helpful to avoid scheduling drops multiple times to save
@ -466,6 +469,7 @@ fn bind_pattern(
arm_span,
match_scope,
schedule_drops,
storages_alive,
);
if arm_scope.is_none() {
schedule_drops = false;
@ -641,6 +645,7 @@ pub(crate) fn place_into_pattern(
None,
None,
None,
false,
)
.unit()
}
@ -1813,6 +1818,7 @@ pub(crate) fn lower_let_expr(
None,
None,
None,
false,
);
post_guard_block.unit()
@ -1836,6 +1842,7 @@ fn bind_and_guard_matched_candidate<'pat>(
arm_span: Option<Span>,
match_scope: Option<region::Scope>,
schedule_drops: bool,
storages_alive: bool,
) -> BasicBlock {
debug!("bind_and_guard_matched_candidate(candidate={:?})", candidate);
@ -2051,7 +2058,12 @@ fn bind_and_guard_matched_candidate<'pat>(
self.cfg.push_fake_read(post_guard_block, guard_end, cause, Place::from(local_id));
}
assert!(schedule_drops, "patterns with guards must schedule drops");
self.bind_matched_candidate_for_arm_body(post_guard_block, true, by_value_bindings);
self.bind_matched_candidate_for_arm_body(
post_guard_block,
true,
by_value_bindings,
storages_alive,
);
post_guard_block
} else {
@ -2065,6 +2077,7 @@ fn bind_and_guard_matched_candidate<'pat>(
.iter()
.flat_map(|(bindings, _)| bindings)
.chain(&candidate.bindings),
storages_alive,
);
block
}
@ -2154,6 +2167,7 @@ fn bind_matched_candidate_for_arm_body<'b>(
block: BasicBlock,
schedule_drops: bool,
bindings: impl IntoIterator<Item = &'b Binding<'tcx>>,
storages_alive: bool,
) where
'tcx: 'b,
{
@ -2163,13 +2177,20 @@ fn bind_matched_candidate_for_arm_body<'b>(
// Assign each of the bindings. This may trigger moves out of the candidate.
for binding in bindings {
let source_info = self.source_info(binding.span);
let local = self.storage_live_binding(
let local = if storages_alive {
// Here storages are already alive, probably because this is a binding
// from let-else.
// We just need to schedule drop for the value.
self.var_local_id(binding.var_id, OutsideGuard).into()
} else {
self.storage_live_binding(
block,
binding.var_id,
binding.span,
OutsideGuard,
schedule_drops,
);
)
};
if schedule_drops {
self.schedule_drop_for_binding(binding.var_id, binding.span, OutsideGuard);
}
@ -2300,6 +2321,7 @@ pub(crate) fn ast_let_else(
None,
None,
None,
true,
);
// This block is for the failure case
let failure = this.bind_pattern(
@ -2311,6 +2333,7 @@ pub(crate) fn ast_let_else(
None,
None,
None,
true,
);
this.break_for_else(failure, *let_else_scope, this.source_info(initializer_span));
matching.unit()