bjoernager/rust
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Auto merge of #114502 - cjgillot:steal-ctfe, r=oli-obk

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Steal MIR for CTFE when possible.

Some bodies, like constants, have CTFE MIR but no optimized MIR.
In that case, have `mir_for_ctfe` steal the MIR instead of cloning it.
This commit is contained in:
bors 2023-08-06 22:02:12 +00:00
commit f3623871cf
1 changed files with 8 additions and 1 deletions
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9
compiler/rustc_mir_transform/src/lib.rs
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@ -338,7 +338,14 @@ fn inner_mir_for_ctfe(tcx: TyCtxt<'_>, def: LocalDefId) -> Body<'_> {
return shim::build_adt_ctor(tcx, def.to_def_id()); return shim::build_adt_ctor(tcx, def.to_def_id());
} }
let body = tcx.mir_drops_elaborated_and_const_checked(def).borrow().clone(); let body = tcx.mir_drops_elaborated_and_const_checked(def);
let body = match tcx.hir().body_const_context(def) {
// consts and statics do not have `optimized_mir`, so we can steal the body instead of
// cloning it.
Some(hir::ConstContext::Const | hir::ConstContext::Static(_)) => body.steal(),
Some(hir::ConstContext::ConstFn) => body.borrow().clone(),
None => bug!("`mir_for_ctfe` called on non-const {def:?}"),
};
let mut body = remap_mir_for_const_eval_select(tcx, body, hir::Constness::Const); let mut body = remap_mir_for_const_eval_select(tcx, body, hir::Constness::Const);
pm::run_passes(tcx, &mut body, &[&ctfe_limit::CtfeLimit], None); pm::run_passes(tcx, &mut body, &[&ctfe_limit::CtfeLimit], None);