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Auto merge of #119677 - cjgillot:early-cfg-opt, r=oli-obk

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Reorder early post-inlining passes.

`RemoveZsts`, `RemoveUnneededDrops` and `UninhabitedEnumBranching` only depend on types, so they should be executed together early after MIR inlining introduces those types.

This does not change the end-result, but this makes the pipeline a bit more consistent.
This commit is contained in:
bors 2024-01-11 04:09:07 +00:00
commit 3a6bf351a3
9 changed files with 27 additions and 44 deletions
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23
compiler/rustc_mir_transform/src/lib.rs
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@ -566,17 +566,28 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
body,
&[
&check_alignment::CheckAlignment,
&lower_slice_len::LowerSliceLenCalls, // has to be done before inlining, otherwise actual call will be almost always inlined. Also simple, so can just do first
// Before inlining: trim down MIR with passes to reduce inlining work.
// Has to be done before inlining, otherwise actual call will be almost always inlined.
// Also simple, so can just do first
&lower_slice_len::LowerSliceLenCalls,
// Perform inlining, which may add a lot of code.
&inline::Inline,
// Substitutions during inlining may introduce switch on enums with uninhabited branches.
// Code from other crates may have storage markers, so this needs to happen after inlining.
&remove_storage_markers::RemoveStorageMarkers,
// Inlining and substitution may introduce ZST and useless drops.
&remove_zsts::RemoveZsts,
&remove_unneeded_drops::RemoveUnneededDrops,
// Type substitution may create uninhabited enums.
&uninhabited_enum_branching::UninhabitedEnumBranching,
&unreachable_prop::UnreachablePropagation,
&o1(simplify::SimplifyCfg::AfterUninhabitedEnumBranching),
&remove_storage_markers::RemoveStorageMarkers,
&remove_zsts::RemoveZsts,
&normalize_array_len::NormalizeArrayLen, // has to run after `slice::len` lowering
// Inlining may have introduced a lot of redundant code and a large move pattern.
// Now, we need to shrink the generated MIR.
// Has to run after `slice::len` lowering
&normalize_array_len::NormalizeArrayLen,
&const_goto::ConstGoto,
&remove_unneeded_drops::RemoveUnneededDrops,
&ref_prop::ReferencePropagation,
&sroa::ScalarReplacementOfAggregates,
&match_branches::MatchBranchSimplification,