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cleanup cfg after optimization

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This commit is contained in:
Simon Vandel Sillesen 2020-09-19 15:21:39 +02:00
parent f472303a93
commit b6f51d6d6a
3 changed files with 15 additions and 8 deletions
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9
compiler/rustc_mir/src/transform/remove_unneeded_drops.rs
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@ -6,6 +6,8 @@ use rustc_middle::mir::visit::Visitor;
use rustc_middle::mir::*; use rustc_middle::mir::*;
use rustc_middle::ty::TyCtxt; use rustc_middle::ty::TyCtxt;
use super::simplify::simplify_cfg;
pub struct RemoveUnneededDrops; pub struct RemoveUnneededDrops;
impl<'tcx> MirPass<'tcx> for RemoveUnneededDrops { impl<'tcx> MirPass<'tcx> for RemoveUnneededDrops {
@ -18,11 +20,18 @@ impl<'tcx> MirPass<'tcx> for RemoveUnneededDrops {
def_id: source.def_id().expect_local(), def_id: source.def_id().expect_local(),
}; };
opt_finder.visit_body(body); opt_finder.visit_body(body);
let should_simplify = !opt_finder.optimizations.is_empty();
for (loc, target) in opt_finder.optimizations { for (loc, target) in opt_finder.optimizations {
let terminator = body.basic_blocks_mut()[loc.block].terminator_mut(); let terminator = body.basic_blocks_mut()[loc.block].terminator_mut();
debug!("SUCCESS: replacing `drop` with goto({:?})", target); debug!("SUCCESS: replacing `drop` with goto({:?})", target);
terminator.kind = TerminatorKind::Goto { target }; terminator.kind = TerminatorKind::Goto { target };
} }
// if we applied optimizations, we potentially have some cfg to cleanup to
// make it easier for further passes
if should_simplify {
simplify_cfg(body);
}
} }
} }

7
src/test/mir-opt/remove_unneeded_drops.opt.RemoveUnneededDrops.diff
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@ -16,10 +16,9 @@
_3 = _1; // scope 0 at $DIR/remove_unneeded_drops.rs:3:10: 3:11 _3 = _1; // scope 0 at $DIR/remove_unneeded_drops.rs:3:10: 3:11
_2 = const (); // scope 1 at $SRC_DIR/core/src/mem/mod.rs:LL:COL _2 = const (); // scope 1 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
- drop(_3) -> bb1; // scope 1 at $SRC_DIR/core/src/mem/mod.rs:LL:COL - drop(_3) -> bb1; // scope 1 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
+ goto -> bb1; // scope 1 at $SRC_DIR/core/src/mem/mod.rs:LL:COL - }
} -
- bb1: {
bb1: {
StorageDead(_3); // scope 0 at $DIR/remove_unneeded_drops.rs:3:11: 3:12 StorageDead(_3); // scope 0 at $DIR/remove_unneeded_drops.rs:3:11: 3:12
StorageDead(_2); // scope 0 at $DIR/remove_unneeded_drops.rs:3:12: 3:13 StorageDead(_2); // scope 0 at $DIR/remove_unneeded_drops.rs:3:12: 3:13
_0 = const (); // scope 0 at $DIR/remove_unneeded_drops.rs:2:17: 4:2 _0 = const (); // scope 0 at $DIR/remove_unneeded_drops.rs:2:17: 4:2

7
src/test/mir-opt/remove_unneeded_drops.opt_generic_copy.RemoveUnneededDrops.diff
View File

@ -16,10 +16,9 @@
_3 = _1; // scope 0 at $DIR/remove_unneeded_drops.rs:13:10: 13:11 _3 = _1; // scope 0 at $DIR/remove_unneeded_drops.rs:13:10: 13:11
_2 = const (); // scope 1 at $SRC_DIR/core/src/mem/mod.rs:LL:COL _2 = const (); // scope 1 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
- drop(_3) -> bb1; // scope 1 at $SRC_DIR/core/src/mem/mod.rs:LL:COL - drop(_3) -> bb1; // scope 1 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
+ goto -> bb1; // scope 1 at $SRC_DIR/core/src/mem/mod.rs:LL:COL - }
} -
- bb1: {
bb1: {
StorageDead(_3); // scope 0 at $DIR/remove_unneeded_drops.rs:13:11: 13:12 StorageDead(_3); // scope 0 at $DIR/remove_unneeded_drops.rs:13:11: 13:12
StorageDead(_2); // scope 0 at $DIR/remove_unneeded_drops.rs:13:12: 13:13 StorageDead(_2); // scope 0 at $DIR/remove_unneeded_drops.rs:13:12: 13:13
_0 = const (); // scope 0 at $DIR/remove_unneeded_drops.rs:12:36: 14:2 _0 = const (); // scope 0 at $DIR/remove_unneeded_drops.rs:12:36: 14:2