bjoernager/rust
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Move post-elaboration const-checking earlier in the pipeline

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Instead we run `RemoveFalseEdges` and `RemoveUninitDrops` at the
appropriate time. The extra `SimplifyCfg` avoids visiting unreachable
blocks during `RemoveUninitDrops`.
This commit is contained in:
Dylan MacKenzie 2021-11-30 17:05:40 -08:00
parent 3e0e8be037
commit 58c996c3a7
1 changed files with 14 additions and 2 deletions
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16
compiler/rustc_mir_transform/src/lib.rs
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@ -77,7 +77,7 @@ mod simplify_try;
mod uninhabited_enum_branching; mod uninhabited_enum_branching;
mod unreachable_prop; mod unreachable_prop;
use rustc_const_eval::transform::check_consts; use rustc_const_eval::transform::check_consts::{self, ConstCx};
use rustc_const_eval::transform::promote_consts; use rustc_const_eval::transform::promote_consts;
use rustc_const_eval::transform::validate; use rustc_const_eval::transform::validate;
pub use rustc_const_eval::transform::MirPass; pub use rustc_const_eval::transform::MirPass;
@ -447,8 +447,20 @@ fn mir_drops_elaborated_and_const_checked<'tcx>(
let (body, _) = tcx.mir_promoted(def); let (body, _) = tcx.mir_promoted(def);
let mut body = body.steal(); let mut body = body.steal();
// IMPORTANT
remove_false_edges::RemoveFalseEdges.run_pass(tcx, &mut body);
// Do a little drop elaboration before const-checking if `const_precise_live_drops` is enabled.
//
// FIXME: Can't use `run_passes` for these, since `run_passes` SILENTLY DOES NOTHING IF THE MIR
// PHASE DOESN'T CHANGE.
if check_consts::post_drop_elaboration::checking_enabled(&ConstCx::new(tcx, &body)) {
simplify::SimplifyCfg::new("remove-false-edges").run_pass(tcx, &mut body);
remove_uninit_drops::RemoveUninitDrops.run_pass(tcx, &mut body);
check_consts::post_drop_elaboration::check_live_drops(tcx, &body);
}
run_post_borrowck_cleanup_passes(tcx, &mut body); run_post_borrowck_cleanup_passes(tcx, &mut body);
check_consts::post_drop_elaboration::check_live_drops(tcx, &body);
tcx.alloc_steal_mir(body) tcx.alloc_steal_mir(body)
} }