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Avoid hashing when creating a DepNode from a HirId #44335

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Merged
merged 1 commit into from
Sep 9, 2017
Merged

Avoid hashing when creating a DepNode from a HirId #44335

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21 changes: 20 additions & 1 deletion src/librustc/dep_graph/dep_node.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -62,7 +62,7 @@

use hir::def_id::{CrateNum, DefId};
use hir::map::DefPathHash;
use hir::HirId;
use hir::{HirId, ItemLocalId};

use ich::Fingerprint;
use ty::{TyCtxt, Instance, InstanceDef};
Expand Down Expand Up @@ -638,6 +638,25 @@ impl<'a, 'gcx: 'tcx + 'a, 'tcx: 'a> DepNodeParams<'a, 'gcx, 'tcx> for (DefIdList
}
}

impl<'a, 'gcx: 'tcx + 'a, 'tcx: 'a> DepNodeParams<'a, 'gcx, 'tcx> for (HirId,) {
const CAN_RECONSTRUCT_QUERY_KEY: bool = false;

// We actually would not need to specialize the implementation of this
// method but it's faster to combine the hashes than to instantiate a full
// hashing context and stable-hashing state.
fn to_fingerprint(&self, tcx: TyCtxt) -> Fingerprint {
let (HirId {
owner,
local_id: ItemLocalId(local_id),
},) = *self;

let def_path_hash = tcx.def_path_hash(DefId::local(owner));
let local_id = Fingerprint::from_smaller_hash(local_id as u64);

def_path_hash.0.combine(local_id)
}
}

/// A "work product" corresponds to a `.o` (or other) file that we
/// save in between runs. These ids do not have a DefId but rather
/// some independent path or string that persists between runs without
Expand Down