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Auto merge of #76659 - simonvandel:76432, r=oli-obk

SimplifyComparisonIntegral: fix miscompilation

Fixes #76432
Only insert StorageDeads if we actually removed one.
Fixes an issue where we added StorageDead to a place with no StorageLive

r? `@oli-obk`
This commit is contained in:
bors 2020-09-23 08:23:00 +00:00
commit feca2c229e
3 changed files with 154 additions and 21 deletions

View file

@ -61,26 +61,6 @@ impl<'tcx> MirPass<'tcx> for SimplifyComparisonIntegral {
_ => unreachable!(),
}
let terminator = bb.terminator_mut();
// add StorageDead for the place switched on at the top of each target
for bb_idx in new_targets.iter() {
storage_deads_to_insert.push((
*bb_idx,
Statement {
source_info: terminator.source_info,
kind: StatementKind::StorageDead(opt.to_switch_on.local),
},
));
}
terminator.kind = TerminatorKind::SwitchInt {
discr: Operand::Move(opt.to_switch_on),
switch_ty: opt.branch_value_ty,
values: vec![new_value].into(),
targets: new_targets,
};
// delete comparison statement if it the value being switched on was moved, which means it can not be user later on
if opt.can_remove_bin_op_stmt {
bb.statements[opt.bin_op_stmt_idx].make_nop();
@ -106,14 +86,35 @@ impl<'tcx> MirPass<'tcx> for SimplifyComparisonIntegral {
}
}
let terminator = bb.terminator();
// remove StorageDead (if it exists) being used in the assign of the comparison
for (stmt_idx, stmt) in bb.statements.iter().enumerate() {
if !matches!(stmt.kind, StatementKind::StorageDead(local) if local == opt.to_switch_on.local)
{
continue;
}
storage_deads_to_remove.push((stmt_idx, opt.bb_idx))
storage_deads_to_remove.push((stmt_idx, opt.bb_idx));
// if we have StorageDeads to remove then make sure to insert them at the top of each target
for bb_idx in new_targets.iter() {
storage_deads_to_insert.push((
*bb_idx,
Statement {
source_info: terminator.source_info,
kind: StatementKind::StorageDead(opt.to_switch_on.local),
},
));
}
}
let terminator = bb.terminator_mut();
terminator.kind = TerminatorKind::SwitchInt {
discr: Operand::Move(opt.to_switch_on),
switch_ty: opt.branch_value_ty,
values: vec![new_value].into(),
targets: new_targets,
};
}
for (idx, bb_idx) in storage_deads_to_remove {