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Avoid calling fn_sig query during is_const_fn_raw

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This commit is contained in:
Dylan MacKenzie 2020-04-09 14:56:19 -07:00
parent e8b270a4b6
commit eb74096a32
1 changed files with 10 additions and 17 deletions
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27
src/librustc_mir/const_eval/fn_queries.rs
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@ -99,8 +99,16 @@ fn is_const_fn_raw(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
let node = tcx.hir().get(hir_id);
if let Some(whitelisted) = is_const_intrinsic(tcx, def_id) {
whitelisted
if let hir::Node::ForeignItem(hir::ForeignItem { kind: hir::ForeignItemKind::Fn(..), .. }) =
node
{
// Intrinsics use `rustc_const_{un,}stable` attributes to indicate constness. All other
// foreign items cannot be evaluated at compile-time.
if let Abi::RustIntrinsic | Abi::PlatformIntrinsic = tcx.hir().get_foreign_abi(hir_id) {
tcx.lookup_const_stability(def_id).is_some()
} else {
false
}
} else if let Some(fn_like) = FnLikeNode::from_node(node) {
if fn_like.constness() == hir::Constness::Const {
return true;
@ -116,21 +124,6 @@ fn is_const_fn_raw(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
}
}
/// Const evaluability whitelist is here to check evaluability at the
/// top level beforehand.
fn is_const_intrinsic(tcx: TyCtxt<'_>, def_id: DefId) -> Option<bool> {
if tcx.is_closure(def_id) {
return None;
}
match tcx.fn_sig(def_id).abi() {
Abi::RustIntrinsic | Abi::PlatformIntrinsic => {
Some(tcx.lookup_const_stability(def_id).is_some())
}
_ => None,
}
}
/// Checks whether the given item is an `impl` that has a `const` modifier.
fn is_const_impl_raw(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);