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Rollup merge of #91410 - ecstatic-morse:const-precise-live-drops-take-2, r=oli-obk

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Move `#![feature(const_precise_live_drops)]` checks earlier in the pipeline

Should mitigate the issues found during MCP on #73255.

Once this is done, we should clean up the queries a bit, since I think `mir_drops_elaborated_and_const_checked` can be merged back into `mir_promoted`.

Fixes #90770.

cc ``@rust-lang/wg-const-eval``
r? ``@nikomatsakis`` (since they reviewed #71824)
This commit is contained in:
Matthias Krüger 2021-12-02 22:16:13 +01:00 • committed by GitHub
commit 39641319ad
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15 changed files with 275 additions and 32 deletions
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24
compiler/rustc_mir_transform/src/lib.rs
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@ -60,8 +60,10 @@ mod match_branches;
mod multiple_return_terminators;
mod normalize_array_len;
mod nrvo;
mod remove_false_edges;
mod remove_noop_landing_pads;
mod remove_storage_markers;
mod remove_uninit_drops;
mod remove_unneeded_drops;
mod remove_zsts;
mod required_consts;
@ -75,7 +77,7 @@ mod simplify_try;
mod uninhabited_enum_branching;
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::validate;
use rustc_mir_dataflow::rustc_peek;
@ -444,8 +446,20 @@ fn mir_drops_elaborated_and_const_checked<'tcx>(
let (body, _) = tcx.mir_promoted(def);
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);
check_consts::post_drop_elaboration::check_live_drops(tcx, &body);
tcx.alloc_steal_mir(body)
}
@ -455,7 +469,7 @@ fn run_post_borrowck_cleanup_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tc
let post_borrowck_cleanup: &[&dyn MirPass<'tcx>] = &[
// Remove all things only needed by analysis
&simplify_branches::SimplifyBranches::new("initial"),
&simplify_branches::SimplifyConstCondition::new("initial"),
&remove_noop_landing_pads::RemoveNoopLandingPads,
&cleanup_post_borrowck::CleanupNonCodegenStatements,
&simplify::SimplifyCfg::new("early-opt"),
@ -514,13 +528,13 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
&instcombine::InstCombine,
&separate_const_switch::SeparateConstSwitch,
&const_prop::ConstProp,
&simplify_branches::SimplifyBranches::new("after-const-prop"),
&simplify_branches::SimplifyConstCondition::new("after-const-prop"),
&early_otherwise_branch::EarlyOtherwiseBranch,
&simplify_comparison_integral::SimplifyComparisonIntegral,
&simplify_try::SimplifyArmIdentity,
&simplify_try::SimplifyBranchSame,
&dest_prop::DestinationPropagation,
&simplify_branches::SimplifyBranches::new("final"),
&simplify_branches::SimplifyConstCondition::new("final"),
&remove_noop_landing_pads::RemoveNoopLandingPads,
&simplify::SimplifyCfg::new("final"),
&nrvo::RenameReturnPlace,