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Recognize discriminant reads as no-ops in RemoveNoopLandingPads

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The cleanup blocks often contain read of discriminants. Teach
RemoveNoopLandingPads to recognize them as no-ops to remove
additional no-op landing pads.
This commit is contained in:
Tomasz Miąsko 2020-10-10 00:00:00 +00:00
parent 0e022fc2b8
commit ecd7862dfb
1 changed files with 1 additions and 1 deletions
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compiler/rustc_mir/src/transform/remove_noop_landing_pads.rs
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@ -43,7 +43,7 @@ impl RemoveNoopLandingPads {
// These are all nops in a landing pad
}
StatementKind::Assign(box (place, Rvalue::Use(_))) => {
StatementKind::Assign(box (place, Rvalue::Use(_) | Rvalue::Discriminant(_))) => {
if place.as_local().is_some() {
// Writing to a local (e.g., a drop flag) does not
// turn a landing pad to a non-nop